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Comitê Diretor do CERPCH Director Committee CEMIG / FAPEPE / IEE-USP / FURNAS / IME / ELETROBRAS / ANEEL / MME Comitê Editorial Editorial Committee Presidente - President Geraldo Lúcio Tiago Filho - CERPCH/UNIFEI Editores Associados - Associated Publishers Adair Matins - UNCOMA - Argentina Alexander Gajic - University of Serbia Alexandre Kepler Soares - UFMT Ângelo Rezek - ISEE/UNIFEI Antônio Brasil Jr. - UnB Artur de Souza Moret - UNIR Augusto Nelson Carvalho Viana - IRN/UNIFEI Bernhard Pelikan - Bodenkultur Wien - Áustria Carlos Barreira Martines - UFMG Célio Bermann - IEE/USP Edmar Luiz Fagundes de Almeira - UFRJ Fernando Monteiro Figueiredo - UnB Frederico Mauad - USP Helder Queiroz Pinto Jr. - UFRJ Jaime Espinoza - USM - Chile José Carlos César Amorim - IME Marcelo Marques - IPH/UFRGS Marcos Aurélio V. de Freitas - COPPE/UFRJ Maria Inês Nogueira Alvarenga - IRN/UNIFEI Orlando Aníbal Audisio - UNCOMA - Argentina Osvaldo Livio Soliano Pereira - UNIFACS Regina Mambeli Barros - IRN/UNIFEI Zulcy de Souza - LHPCH/UNIFEI Editorial Editorial Curta News Opinion Lei 13.097 altera tributação para energias renováveis Law 13.097 changes renewable energy tax Agenda 34 Schedule Ficha catalográfica elaborada pela Biblioteca Mauá – Bibliotecária Margareth Ribeiro- CRB_6/1700 R454 Revista Hidro & Hydro – PCH Notícias & Ship News, UNIFEI/CERPCH, v.1, 1998 -- Itajubá: CERPCH/IARH, 1998 – v.15, n. 64,jan./mar. 2015. Expediente Editorial Tradução Impressão 06 Opinião Prof. François AVELLAN, EPFL École Polytechnique Fédérale de Lausanne, Switzerland, [email protected], Chair; Prof. Eduardo EGUSQUIZA, UPC Barcelona, Spain, [email protected], Vice-Chair; Dr. Richard K. FISHER, VOITH Hydro Inc., USA, [email protected], Past-Chair; Mr. Fidel ARZOLA, EDELCA, Venezuela, [email protected]; Dr. Michel COUSTON, ALSTOM Hydro, France, [email protected]; Dr. Niklas DAHLBÄCK, VATENFALL, Sweden, [email protected]; Mr. Normand DESY, ANDRITZ Hydro Ltd., Canada, [email protected]; Prof. Chisachi KATO, University of Tokyo, Japan, [email protected]; Prof. Jun Matsui, Yokohama National University, [email protected]; Dr. Andrei LIPEJ, TURBOINSTITUT, Slovenija, [email protected]; Prof. Torbjørn NIELSEN, Norwegian University of Science and Technology, Norway, [email protected]; Mr. Quing-Hua SHI, Dong Feng Electrical Machinery, P.R. China, [email protected]; Prof. Romeo SUSAN-RESIGA, “Politehnica” University Timisoara, Romania, [email protected]; Prof. Geraldo TIAGO F°, Universidade Federal de Itajubá, Brazil, [email protected]. Geraldo Lúcio Tiago Filho Camila Rocha Galhardo Adriana Barbosa MTb-MG 05984 Adriana Barbosa Camila Rocha Galhardo Net Design Lidiane Silva 06 A Viabilidade de Aplicação da Resolução 482 na Implantação de Sistemas de Geração Fotovoltaica nas Atuais Condições de Mercado Application Feasibility of Resolution 482 in the Implementation of Solar Power Systems in the Current Market Conditions TECHNICAL COMMITTEE Editor Coord. Redação Jornalista Resp. Redação Projeto Gráfico Diagramação e Arte 04 Trimestral. Editor chefe: Geraldo Lúcio Tiago Filho. Jornalista Responsável: Adriana Barbosa – MTb_MG 05984 ISSN 2359-6147 / ISSN 1676-0220 1. Energia renovável. 2. PCH. 3. Energia eólica e solar. 4. Usinas hi_ drelétricas. I. Universidade Federal de Itajubá. II. Centro Nacional de Re_ ferência em Pequenas Centrais Hidrelétricas. III. Título. Joana Sawaya de Almeida Editora Acta Ltda Hidro&Hydro - PCH Notícias & SHP News é uma publicação trimestral do CERPCH The Hidro&Hydro - PCH Notícias & SHP News is a three-month period publication made by CERPCH Tiragem/Edition: 6.700 exemplares/issues contato comercial: [email protected] / site: www.cerpch.org.br Universidade Federal de Itajubá ISSN 2359614-7 Av. BPS, 1303 - Bairro Pinheirinho Itajubá - MG - Brasil - CEP: 37500-903 e-mail: [email protected] [email protected] Fax/Tel: +55 (35)3629 1443 9 772359 614009 00064 3 EDITORIAL HIDRO&HYDRO: PCH NOTÍCIAS & SHP NEWS, 64 (5), JAN,FEV,MAR/2015 Dear readers, Prezado Leitor, Ao longo dos últimos 17 anos a revista PCH Notícias &SHP News passou por diversas transformações buscando se adequar a época e as necessidades do mercado. A publicação que foi concebida com intuito de divulgar notícias e a produção científica na área de pequenas centrais hidrelétricas. Nos últimos anos foram feitas adequações para ampliar a sua abrangência, passando a ser denominada Hidro & Hydro com publicação de matérias e artigos científicos de outras fontes de energias renováveis. Entretanto a proposta não se mostrou adequada. Desta forma, a partir dessa primeira edição do ano a revista foi desdobrada em duas publicações independentes, onde a Hidro & Hydro com ISSN próprio publicará em páginas coloridas matérias e reportagens sobre temas relevantes ao setor elétrico. É essa revista que, a partir de agora, estampará os apoios institucionais, tão importantes a esta revista, visto que é com o apoio dos anunciantes que a revista pode publicada. Já a PCH Notícias &SHP News se dedicará exclusivamente para a divulgação de produção científica com o ISSN já existente. Assim, pretende-se segmentar os conteúdos de maneira a não perder a credibilidade conquistada nesses anos. Vale ressaltar que a publicação continuará sendo de distribuição gratuita e as mesmas serão impressas juntas. Para a submissão de artigos técnicos na revista, o pesquisador agora deverá submetê-lo por meio do site www.cerpch.org.br onde está disponibilizada uma plataforma em que o autor terá acesso a todas as etapas de avaliação e no final da avaliação e com sua aprovação o artigo será indexado com o respectivo Digital Object Identifier – DOI, identificação esta que auxilia na referencia do mesmo para citações. Por fim, o comitê editorial da revista visa cada dia mais fazer com que a publicação seja referência para seus leitores, colaboradores e patrocinadores. Esperando continuar a contar com o apoio e colaboração de todos. Over the last 17 years, the magazine PCH Notícias & SHP News has gone through several transformations in order to adapt to market times and needs. Its publication was conceived with the intention of spreading the news and scientific production on small hydropower plants. In the last few years, adjustments were made in order to branch out its reach, with adjustments such as the new name Hidro & Hydro as well as publications of scientific articles and subjects of other renewable sources. However, it did not prove to be enough. Therefore, for this first edition of 2015, the magazine has been divided into 2 independent publications, Hidro & Hydro and PCH Notícias & SHP News. Hidro & Hydro now has its own ISSN and will be publishing color printed articles and reports on themes relevant to the electric sector. This is the magazine that here on out will print the institutional support which is tremendously important to the magazine, as it is with those advertisements that the magazine can be published. The other, PCH Notícias & SHP News, will be exclusively dedicated to promoting scientific productions with the existing ISSN. The content is intended to be segmented, so as not to lose the credibility that has been attained over the years. It is worth mentioning that both magazines will continue to be distributed free of charge and both will also be printed together as one. For the submission of technical articles in the magazine, the researcher must now submit it through the website: www.cerpch.org.br where the author can have access to all of the approval stages, from evaluation to final approval of the article. Articles will be indexed with the Digital Object Identifier – DOI, the identification that aids in referencing citations. On a final note, the editorial committee of the magazine is aiming to continuously make it so this publication is made a reference to the readers, collaborators and sponsors. Hoping to continue to count on everyone’s support and collaboration. Enjoy reading! Boa Leitura! Geraldo Lúcio Tiago Filho Geraldo Lúcio Tiago Filho Apoio: IAHR DIVISION I: HYDRAULICS TECHNICAL COMMITTEE: HYDRAULIC MACHINERY AND SYSTEMS 4 5 CURTAS HIDRO&HYDRO: PCH NOTÍCIAS & SHP NEWS, 64 (5), JAN,FEV,MAR/2015 A VIABILIDADE DE APLICAÇÃO DA RESOLUÇÃO 482 NA IMPLANTAÇÃO DE SISTEMAS DE GERAÇÃO FOTOVOLTAICA NAS ATUAIS CONDIÇÕES DE MERCADO Geraldo Lúcio Tiago Filho, 1Luzia Silva Riêra Salomon, 1Laura Campello Dardot, 1,2 Roberto Meira 1,2 Fonte: Salomon, L R, GEER/CERPCH – Unifei- 2014. Source: Salomon, L R, GEER/CERPCH - UNIFEI - 2014. em grande parte, isento desse custo extra, de forma a evitar a O texto a seguir compreende a conclusão das discussões perda de competitividade da indústria alemã. O modelo deu tão desenvolvidas pelo Grupo de Estudos em Energias Renováveis certo que o país aumentou mais de 300 vezes sua geração de – GEER e Centro Nacional de Referências em PCH – CERPCH, da energia solar nos últimos 11 anos e se tornou o líder global no Universidade Federal de Itajubá- UNIFEI e tem como objetivo quesito com 36% das placas fotovoltaicas em operação no mundo, contribuir com as discussões nacionais sobre a sustentabilidade e mais de 65% dos geradores são indivíduos ou comunidades. energética e ambiental da matriz elétrica nacional. No Brasil, os painéis fotovoltaicos, assim como os aerogeradores, O diretor-geral da Agência Nacional de Energia Elétrica são desonerados. Entretanto os custos ainda são altos, que (ANEEL), Romeu Rufino, anunciou que o governo estuda a dificultam, ou até mesmo impedem, a sua proliferação. Em criação de um pacote de medidas para estimular a microgeração estudo desenvolvido Salomon (2014), pesquisadora do Grupo de distribuída no país, ou seja, a geração de energia por pequenos Estudos em Energias Renováveis-GEER, da Universidade Federal de consumidores, de forma descentralizada. Dentre as principais Itajubá, mostra que o custo dos painéis solares para o atendimento medidas estão, a criação de uma linha de crédito para aquisição de residencial, considerando a demanda de energia requerida variando equipamentos como placas solares, biodigestores e conversores, de 5 a 25 kWh/dia, como mostra o Gráfico 1 a seguir. Por exemplo, de modo que os pequenos consumidores possam gerar a própria de acordo com o Gráfico 1, para uma residência que gaste em média energia e, eventualmente, “vender” o excedente produzido à 210 kWh por mês, por exemplo, e a radiação solar local for de 4 distribuidora local, o que hoje não é permitido no Sistema de kWh/m2/dia, o custo estimado para a implantação de um sistema Compensação definido pela Resolução Normativa nº 482/2012 fotovoltaico será por volta de R$ 18.000,00. da ANEEL. Este mesmo gráfico mostra que o custo dos sistemas A atual legislação prevê que a energia injetada pela unidade fotovoltaicos para atendimento residencial pode variar de R$ consumidora por meio da microgeração distribuída seja cedida 11.000,00 a R$ 92.000,00, conforme a incidência solar na à distribuidora local e posteriormente compensada, através de localidade. créditos, pela mesma unidade consumidora. E se, em um prazo Como a radiação média no Brasil é de 4,5 kWh/dia, podede 36 meses, a energia injetada na rede não for consumida pelo se supor que há grande possibilidade de se implantar sistemas microgerador, o saldo de energia é apropriado pela distribuidora. fotovoltaicos. Entretanto, para que se viabilize economicamente a Com esta proposta do Diretor Geral da Aneel, também entra na demanda a ser atendida deverá ser a partir de 25 KWh/dia, muito pauta de discussão a incidência do ICMS sobre a comercialização alta, que corresponde às residências de famílias com alto poder do excedente de energia visto que, atualmente, apenas Minas aquisitivo ou em instalações comerciais e pequenas indústrias. Gerais e o Ceará deixam de tributar essa transação no Sistema de Compensação. As duas medidas são muito importantes para que o mercado da microgeração finalmente deslanche no Brasil. O alto custo dos equipamentos e a falta de incentivo na produção do excedente de energia tornam o prazo de retorno muito longo e o investimento pouco atraente. Em países da Europa como a Alemanha, por exemplo, desde 2000 o governo promove medidas de incentivo a microgeração, principalmente a fotovoltaica. Lá, o cidadão que instala painéis solares em casa tem a garantia de vender a energia gerada por um preço mais alto Gráfico 1: Investimento necessário para implantação de painéis fotovoltaicos em função da demanda que a média do mercado, e de energia requerida e da incidência da radiação solar local. esse subsídio é pago pelos Graph 1: Investment necessary for solar panel implementation based on required energy and local consumidores finais na solar radiation. forma de uma sobretaxa. Mas o setor industrial ficou, Grupo de Estudos de Energias Renováveis- GEER – UNIFEI. Centro Nacional de Referências em PCH – CERPCH – UNIFEI, Universidade Federal de Itajubá - UNIFEI 1 2 6 NEWS HIDRO&HYDRO - PCH NOTÍCIAS & SHP NEWS | ISSN 1676-0220 APPLICATION FEASIBILITY OF RESOLUTION 482 IN THE IMPLEMENTATION OF SOLAR POWER SYSTEMS IN THE CURRENT MARKET CONDITIONS Translation: Joana Sawaya de Almeida The following contains the discussion conclusions developed by the GEER (Renewable Energy Discussion Group) and the CERPCH (National Reference Center for SHPs) of the Federal University of Itajubá - UNIFEI with an objective to contribute to national discussions regarding power and environment sustainability of the national energy matrix. Romeu Rufino, director-general of the National Electric Energy Agency (ANEEL), announced that the government is studying a new set of measures to stimulate micro power production in the country, i.e., power production by consumers in a decentralized way. One of the main measures is to establish a line of credit for the acquisition of equipment such as solar panels, biodigesters and converters, so that consumers could generate their own power and eventually "sell" the surplus to the local distributor. Today, this is something not yet allowed in The Compensation System established by the Normative Resolution 482/2012 of ANEEL. Current legislation foresees that small consumer generated power production be passed on to the local distributor which would later compensate the consumer through credits. If in 36 months the micro producer does not use the injected power in the grid, the distributor would appropriate it. With this proposal from the director-general of ANEEL, the incidence of the ICMS tax (Services Tax over Merchandise Circulation) of surplus energy is also being discussed since only Minas Gerais and Ceará states currently do not tax these transactions in the Compensation System. The two measures are extremely important for the micropower production market to finally take off in Brazil. The high equipment costs and lack on incentives in the surplus energy production make the return on investment very long and unattractive. European countries like Germany, for example, have promoted incentive measures for micropower production, especially solar power, since 2000. In Germany, citizens who install solar panels in their homes are guaranteed to sell the generated power for a higher than average market price and those subsidies are passed on to the consumers in the form of a surcharge. The German industrial sector was largely exempt from this surcharge in order to avoid losing competitiveness. This model worked so well that Germany's solar power production increased 300 fold in the last 11 years. It became the global leader in the sector with 36% of all solar panels in operation worldwide with more than 65% of power production coming from individuals or communities. In Brazil, solar panels as well as wind turbines are tax exempt. However, the cost is still high, hindering or even preventing their proliferation. A study by Salomon (2014), a GEER (Renewable Energy Discussion Group) researcher of the Federal University of Itajubá shows the cost of solar panels for residential use considering the daily energy demand of 5 to 25 kWh, as shown in graphic 1. For example, according to Graph 1, for a home that uses, on average 210 kWh per month, and with a local solar radiation of 4 kWh/m² per day, the estimated cost for the implementation of a solar panel system would be around R$ 18,000.00 reais. The same graphic shows the cost of solar systems for residential use ranging between R$11,000.00 and R$92,000.00 Since average daily solar radiation in Brazil is 4.5 kWh, one can assume that there is a great possibility of implementing solar power systems. However, in order to make it economically feasible, the demand must be higher than 25 kWh/daily inline with homes of high purchasing power or in commercial installations and small industries. With the current available financing conditions, the system is only economically feasible in areas of high solar radiation of around 6 kWh/daily and with power demands higher than 15 kWh/daily. This amount of solar radiation is found in the northeast region of Brazil where the profile of the local consumer, whose purchasing power is not very high, must be taken in consideration. According to Laura Dardot (2014), if one considers just savings on the electric bill alone without the sale of the surplus energy, the financing interest rate would have to be below 6% in order to make solar power systems attractive, considering an investment return of 30 years. On the other hand, if the consumer were to invest in a solar system 60% larger than its needs, the investment would become Renewable Energy Study Group - GEER - UNEIFEI National Reference Center at PCH – CERPCH – UNIFEI, Universidade Federal de Itajubá - UNIFEI 1 2 7 CURTAS Nas atuais condições de financiamento disponíveis, o sistema só se viabiliza economicamente em regiões com alta radiação solar, em torno de 6 kWh/dia e para demanda superiores a 15 KWh/dia. Esta radiação é encontrada na região nordeste do Brasil, onde se deve ser levada em consideração o perfil do consumidor local, cujo poder aquisitivo, em sua maioria, não é muito alto. De acordo com o estudo de Laura Dardot (2014), se considerarmos somente o custo evitado da conta de energia elétrica, sem venda de excedente, a taxa de juros para financiamento teria que estar abaixo de 6% para que o investimento em um sistema fotovoltaico seja atraente, considerando um tempo de retorno de 30 anos. Por outro lado, se o consumidor investisse em um sistema fotovoltaico 60% maior que sua demanda, o investimento se tornaria atraente se o excedente fosse vendido a uma tarifa de R$ 0,90/kWh, um valor abaixo da tarifa cobrada aos grandes consumidores hoje no horário de ponta, considerando uma taxa de juros de 12% e o mesmo tempo de retorno de 30 anos. Para que o investidor tivesse um tempo de retorno do investimento menor, de 15 anos, considerando este último cenário analisado, a tarifa viável para venda do excedente já seria cerca de R$ 1,20/kWh. Ou seja, é preciso fazer um arranjo entre a taxa de juros a ser praticada no financiamento dos equipamentos e a tarifa de venda do excedente de energia produzido pelo pequeno consumidor, para que essas medidas sejam eficientes no sentido de incentivar a microgeração distribuída no país. Para desvincular de forma efetiva da tendência de dimensionamento apenas pela demanda, é necessário que a microgeração fotovoltaica seja atrativa ao “consumidor/gerador local.” É emergencial a necessidade de revisão na Resolução Normativa ANEEL n.º 482/2012 no tocante à possibilidade de venda de energia gerada excedente, tal como já ocorre em alguns países europeus, por exemplo. A efetiva inserção dessa energia distribuída depende de um cenário sob a égide da tríade: técnica, econômica e mercado. A análise deve ser sistêmica e multifocal, permitindo ao consumidor o melhor arranjo em todos esses aspectos. Torna-se necessária a definição de uma política pública mais eficiente para a geração distribuída, além do proposto na Resolução Normativa citada. Esta questão deve ser efetivamente inserida HIDRO&HYDRO: PCH NOTÍCIAS & SHP NEWS, 64 (5), JAN,FEV,MAR/2015 no contexto do planejamento energético nacional com a definição de ações de incentivos de médio e longo prazo no tocante à comercialização e distribuição dessa energia. Cabe ao Ministério de Minas e Energia capitanear esta ação e promover de forma sustentável esta opção de geração, indicando aos investidores nacionais e internacionais, a potencialidade do mercado, as condições de venda dessa energia e, principalmente, em conjunto com outros órgãos públicos competentes, as condições de incentivos governamentais. Há um enorme potencial de aplicação desta alternativa tecnológica no Brasil. Temos sol suficiente e uma cadeia tecnológica madura relacionada à eletrônica e controle, advinda da inserção de outras fontes alternativas renováveis. O necessário agora é promover um ganho de escala nesta aplicação, com regras de financiamento factíveis e incentivos à qualificação e capacitação técnica para a efetiva inserção desta geração distribuída no Brasil. Neste sentido, o GEER/CERPCH propõe ao Ministério de Minas e Energia reavaliar a Resolução Normativa n.º 482/2012, bem como elaborar um estudo de um modelo de financiamento juntamente com os bancos oficiais de forma a contribuir efetivamente na política de diversificação da matriz energética nacional. Dardot, Laura, “Micro Geração Fotovoltaica Residencial: Estudo de Caso na Região Rural de Itajubá“, Seminário Interno GEER, UNIFEI, 2014. Dardot, Laura, "Micro Residential Solar Power Production" Case study in the Rural Region of Itajubá", In-house Seminar GEER, UNIFEI, 2014. Salomon, Luzia R, “título do artigo Análise de viabilidade técnico econômica da geração solar fotovoltaica aplicada no setor de consumo Residencial, no Brasil” Seminário Interno, GEER, UNIFEI, 2014. Salomon, Luzia R, Article title: "Análise de viabilidade técnico econômica da geração solar fotovoltaica aplicada no setor de consumo Residencial no Brasil”. In-house Seminar GEER, UNIFEI, 2014. 8 NEWS HIDRO&HYDRO - PCH NOTÍCIAS & SHP NEWS | ISSN 1676-0220 attractive if the surplus could be sold at R$ 0.90/kWh, a rate lower than what consumers currently pay during peak hours, considering an interest rate of 12% and the same investment return of 30 years. Considering this last scenario, the investor would need to sell the surplus energy produced at a rate of R$ 1,20/kWh for a return on investment of less than15 years. In other words, there must be a balance between the financing interest rate of the equipment and the price of the surplus energy produced by the consumer for these measures to be efficient in stimulating micropower production in the country. To effectively disassociate the tendency to scale simply by demand, it is important that micro solar power production be attractive to the "local producer/consumer". There is an urgent need for ANEEL to revise the Normative Resolution 482/2012 to allow the sale of the produced surplus energy, as already seen in some European countries. The effective implementation of this distributed energy is dependent on a scenario under the aegis of the technical, economic and market triad. The analysis must be systemic and multifocal allowing the consumer a better arrangement in all aspects. It is necessary to define a more efficient public policy for the distributed production, in addition to the proposed Normative Resolution cited. This issue should effectively be put in the context of the national energy planning with defined medium and long-term incentives for the marketing and distribution of that energy. It is the responsibility of the Ministry of Mines and Energy to lead with this action and sustainably promote this generating option by showing national and international investors the market potential, energy sales conditions and the types of government incentives especially in conjunction with other public agencies. There is a huge potential for the implementation of this alternative technology in Brazil. Brazil has enough sunshine and a mature electronics and control technological chain from the inclusion of other alternative renewable energy sources. The need now is to promote a gain of scale in this application, with practical funding rules and incentives for training and technical leadership to effectively apply this production throughout Brazil. In this respect, GEER and CERPCH are proposing that the Ministry of Mines and Energy reevaluate the Normative Resolution 482/2012 and conduct a funding model study with the official banks in order to effectively contribute to the diversification of the national energy policy. Movidos por desafios www.snef.com.br [email protected] 51 31 2103-2200 A SNEF dispõe de equipe e know-how em serviços de reforma e modernização de equipamentos eletromecânicos para usinas hidrelétricas e subestações. Profissionais qualificados para atuar em gerenciamento, projeto, fabricação, montagem, comissionamento e diagnóstico. Reforma e Modernização de Usinas Hidrelétricas e Subestações 9 28 e 29 de ABRIL de 2015 UNIVERSIDADE NACIONAL DE LA PLATA, FACULDADE DE ENGENHARIA, DEPARTAMENTO DE HIDRÁULICA, LA PLATA, ARGENTINA TEMARIO O Grupo de Trabalho Latino Americano do Comitê de Máquinas Hidráulicas e Sistemas da IAHR, tem o prazer de convidá-lo ao II Latin American Hydropower and Systems Meeting onde se encontrarão profissionais e pesquisadores da área de máquinas hidráulicas. Para mais informações e submissão de artigos científicos, por favor visite nosso site. www.latiniahr.org/meeting RESERVE A DATA PROMOÇÃO MÁQUINAS HIDRÁULICAS SISTEMAS DE CONTROLE E MONITORAMENTO MODELAGEM E SIMULAÇÃO FENÔMENOS DE TRANSPORTE APROVEITAMENTO HIDROENERGÉTICO SISTEMAS DE BOMBEAMENTO TECNOLOGIA OCEÂNICA MERCADO ENERGÉTICO EFICIÊNCIA ENERGÉTICA ESTUDOS DE CASOS GRUPO DE TRABALHO LATINO AMERICANO – COMITÊ DE MÁQUINAS HIDRÁULICAS E SISTEMAS DA IAHR Durante a realização do “25th IAHR Symposium on Hydraulic Machinery and Systems”, realizado em setembro de 2010 na Romênia, foi lançada a proposta de criação de um grupo latino americano para ampliar as discussões na área de máquinas hidráulicas e sistemas sob a coordenação da "International Association for Hydraulic Research". Até o momento, o grupo possui 19 entidades participantes, entre elas, ALSTOM, ANDRITZ, IMPSA, KSB, VOITH e as Universidades: IME, UFMG, UFMT, UFRGS, UFRJ, UnB, UNICAMP, UNIFEI,USP e as Argentinas UNAM, UNCOMA, UNCU, UNLP, UTN - Regional Mendoza. ORGANIZAÇÃO latinamerican WORKING GROUP Universidad Nacional de La Plata 11 OPINIÃO HIDRO&HYDRO: PCH NOTÍCIAS & SHP NEWS, 64 (5), JAN,FEV,MAR/2015 LEI 13.097 ALTERA TRIBUTAÇÃO PARA ENERGIAS RENOVÁVEIS Da Redação A Lei 13.097 sancionada pela presidente, Dilma Rousseff, em 20 de janeiro de 2015 traz algumas alterações no que se diz respeito a energias renováveis, em especial a energia eólica e as pequenas centrais hidrelétricas. A iniciativa de desoneração tributária de partes utilizadas em aerogeradores vem ao encontro da proposta da Medida Provisória n.º 656/2014. Entretanto a redação sancionada em lei pode ser considerada tacanha, uma vez que limita demasiadamente o alcance do benefício, excluindo componentes e insumos que não se enquadram no “Ex 01 do código 8503.00.90 da TIPI” não foram contemplados pela norma outros importantes componentes utilizados como insumos na fabricação de aerogeradores, dentre os quais as próprias torres. Deixaram também de ser mencionadas a prestação de serviços e as locações de máquinas, aparelhos, instrumentos e equipamentos. Na opinião dos pesquisadores do CERPCH, essa mudança pode impactar de forma favorável para o crescimento de empreendimentos eólicos no país, facilitando a aquisição de sistemas de geração eólica. Mas, por outro lado, essa desoneração para importação dificulta o incentivo para o desenvolvimento de tecnologia nacional, gerando pouco interesse das empresas em investir no desenvolvimento tecnológico nacional. O grupo entende que a redução de alíquotas relacionadas à importação podem induzir uma abertura maior de mercado a produtos importados, com possíveis impactos na cadeia nacional Dessa forma, entende-se que pode haver uma retração da cadeia nacional uma vez que muitos insumos continuam tributados e desta maneira pode ocorrer que os valores praticados comercialmente sejam superiores aos produtos vindos do exterior. A redefinição do aproveitamento do potencial hidráulico é um assunto que vem sendo debatido no governo desde 2008, a destacar o Projeto de Lei nº 4.004/2008, a Medida Provisória n.º 450/2009 e a Lei nº 11.943/2009. Mesmo após essas revisões a Lei n.º 9.427/1996 continuava em desfavor dos autoprodutores. 12 Devido ao atual cenário da geração de energia elétrica brasileiro, submetido à uma forte restrição hídrica e em vias de racionamento, os pesquisadores do CERPCH analisaram os termos aprovados nesta lei e concluíram que: a ampliação da potência das CGHs para 3 MW irá promover uma desburocratização do processo junto à Agência Nacional de Energia Elétrica. Atualmente, com base no Relatório de Acompanhamento de Estudos e Projetos de Usinas Hidrelétricas da Superintendência de Concessões e Autorizações de Geração da própria agência, tramitam atualmente 1.798 pedidos de autorizações para PCHs no âmbito da agencia, totalizando 15.610 MW de potência instalada. Desse universo, 502 empreendimentos hidrelétricos então entre 1 e 3 MW, correspondendo a um total de 977 MW de potência instalada. Com esta nova Lei 28% dos empreendimentos hidroenergéticos passam ter como atração a simplicidade burocrática junto ao órgão regulador. Isto pode ser um motivador à efetiva instalação desses empreendimentos, o que significa num cenário de 20 anos, a possibilidade destas CGHs gerarem cerca de 3 mil empregos diretos e indiretos por ano e fomentar um mercado de aproximadamente de 6 bilhões de reais. Ressalta-se que o relatório da Aneel abrange registros em níveis de análise distintos, tais como as etapas de registro, análise e aprovação de estudos de inventário hidrelétrico de bacias hidrográficas, estudos de viabilidade e projeto básico de usinas hidrelétricas (UHEs), bem como de projeto básico de pequenas centrais hidrelétricas (PCHs). E dependerá do empreendedor a ação de proceder o registro destes empreendimentos nestas novas condições. A Lei também deveria tratar da desoneração da biomassa. Entretanto, os artigos que previam a desoneração do PIS/PASEP sobre a transferência de vapor e de biomassa para unidades de cogeração, itens incluídos na Medida Provisória 656, que originou esta Lei, foram vetados pela presidente Dilma Rousseff, sem os incentivos fiscais, essas fontes de energia perderão atratividade no mercado de energia, uma vez que outras fontes renováveis já recebem estes subsídios do governo. Com relação à desoneração das tarifas de transmissão de energia elétrica (TUST e TUSD), houve um nivelamento entre as diferentes fontes, a de energia solar, que contava com uma amortização que variava entre 80% a 100% passará a ter uma amortização que pode variar de 50% a 100%, tal como já ocorre com as PCHs, ou seja, com esta ação houve um nivelamento destas fontes às PCHs. HIDRO&HYDRO - PCH NOTÍCIAS & SHP NEWS | ISSN 1676-0220 OPINION LAW 13.097 CHANGES RENEWABLE ENERGY TAX Translation: Joana Sawaya de Almeida Law 13.097, sanctioned by President Dilma Rousseff on January 20th 2015, brings some changes with regard to renewable energy; particularly wind power and small hydroelectric power plants. The tax exemption initiative for parts used in wind turbines comes inline with the proposal of the Provisional Measure 656/2014. However, the wording in the enacted law can be considered narrow since it limits the scope of the benefit by excluding components and supplies that do not fit the "Ex 01 8503.00.90 of the TIPI code". The law did not cover other important components such as supplies for wind power manufacturing and the actual towers themselves. Other items like, rental and maintenance of machinery, equipment and instruments were also failed to be mentioned. In the opinion of CERPCH researchers, this change could favorably impact the growth of wind power investment in the country, by aiding in the acquisition of wind power systems. On the other hand, import tax exemptions hinder the incentive for the development of national technologies, which in turn creates very little investment interest from companies. The group believes that import tax exemptions can lead to the market opening up to imports with a possible impact on the national product chain. Since large numbers of supplies continue to be taxed, there may be a retraction in the national chain due to the higher commercial costs compared to the imports. Redefining the use of the hydroelectric power potential is a subject that has been debated within the government since 2008, notably with Proposed Bill 4.004/2008, Interim Measure 450/2009 and Law 11.943/2009. Producers continue hampered even after the revisions of the Law 9.427/1996. Due to the current Brazilian electric power production scenario, which is under severe water restriction and undergoing rationing, <s0/> CERPCH researchers analyzed the terms approved in this law and concluded that: the increase of Hydroelectric Power Plants capacity to 3 MW will remove the red tape from the process at the National Electric Energy Agency. Currently, based on the agency’s own Study and Followup Report of Hydroelectric Power Plants Projects from the Concessions and Permits Administration (SCG), there are currently 7.798 Small Hydroelectric Power Plant permits awaiting approval, totaling 15.610 MW of installed capacity. Of those, 502 hydroelectric projects range between 1 and 3 MW representing a total of 977 MW of installed capacity. With this new law, 28% of the hydroelectric projects will now benefit from less red tape from the regulatory agency. This could be a motivating factor for the actual installation of those hydroelectric projects. In 20 years these SHPs could create three thousand direct and indirect jobs a year and fuel the economy by approximately six billion reais. It should be noted that the ANEEL report encompasses records in distinct levels of analysis such as, registration steps, review and approval of hydropower river basin inventory studies, project feasibility and basic design studies of hydropower plants (HPPs) as well as basic design of small hydroelectric power plants (SHP). It is up to the investor to proceed with the registration of those projects under these new conditions. The law should also deal with the tax exemption for biomass. However, the articles that allowed for the exemption of the PIS/ PASEP tax on the transfer of steam and biomass for cogeneration units, items included in the Provisional Measure 656 giving rise to this Act, were vetoed by < f0> President Dilma Rousseff. Without tax incentives, these energy sources will lose appeal in the energy market since other renewable sources already receive these government grants. In terms of the tariff exemption for electricity transmission (TUST and TUSD), there was a leveling between the different sources like solar power, which had amortization ranging from 80 to 100 % and will now have amortization ranging from 50 to 100 %, as is the case with the Small Hydroelectric Power Plants (SHPs). With this action all tariff exemptions of these sources were leveled to those of the Small Hydroelectric Power Plants (SHPs). 13 AGENDA/SCHEDULE EVENTOS LIGADOS AO SETOR DE ENERGIA - 2015 FEVEREIRO Mexico WindPower 2015 Data: 25/02/2015 a 26/02/2015 Local: Centro Banamex - Cidade do México – México E-mail: [email protected] Site: http://www.mexicowindpower.com.mx/ BioEnergy Italy 2015 Data: 25/02/2015 a 27/02/2015 Local: Itália E-mail: [email protected] Site: http://www.bioenergyitaly.com MARÇO ICE Nuclear 2015; Developing the UK's Industry Data: 25/03/2015 Local: Westminster, UK E-mail: [email protected] Site: http://www.ice-conferences.com/ice-nuclear-2015/ 11th Energy Efficiency and Renewable Energy Congress and Exhibition for South-East Europe Data: 11/03/2015 a 13/03/2015 Local: Sofia-Capital - Bulgária Site: http://www.eea.europa.eu/events/11th-energy-efficiencyrenewable-energy 2nd International e-Conference on Energies Data: 16/03/2015 a 31/03/2015 Local: On-line E-mail: [email protected] Site: http://www.sciforum.net/conference/ece-1/ ABRIL Cenocon 2015 Data: 13/04/2015 a 14/04/2015 Local: Pestana São Paulo Hotel & Conference Center - São Paulo - SP Site: http://www.rpmbrasil.com.br/index.aspx Enase 2015 Data: 29/04/2015 a 30/04/2015 Local: Barcelona, Espanha http://www.enase.org JUNHO InterSolar 2015 Data: 09/06/2015 a 10/06/2015 Local: München – Deutschland Site: http://conference.intersolar.de 14 NEWS HIDRO&HYDRO: PCH NOTÍCIAS & SHP NEWS, 64 (5), JAN,FEV,MAR/2015 II SRN – Seminário de Recursos Naturais, Sustentabilidade e Tecnologias Ambientais Data: 09/06/2015 a 12/06/2015 Local: Universidade Federal de Itajubá – UNIFEI/EXCEN Site: http://www.cerpch.unifei.edu.br/semear Feira Internacional de energias renováveis – All About energy 2015 Data: 10 a 12 de junho de 2015 Local: Fortaleza/CE AGOSTO 12º COBEE - Congresso Brasileiro de Eficiência Energética Data: 25 e 26 de agosto de 2015 Local: Centro de Convenções Frei Caneca - São Paulo – SP Site: http://www.cobee.com.br Fenasucro - 23ª Feira Internacional de Tecnologia Sucroenergética Data: 25 a 28 de agosto de 2015 Local: Sertãozinho - São Paulo – SP Site: http://www.fenasucro.com.br/ SETEMBRO Brazil Windpower 2015 1 a 3 de setembro de 2015 Rio de Janeiro – RJ Intersolar South America Data: 01 a 03 de setembro de 2015 Local: Expo Center Norte - São Paulo – SP Site: http://www.intersolar.net.br/pt/intersolar-south-america.html EU PVSEC Data: 14 a 18 de setembro de 2015 Local: Hamburg - Deutschland Site: http://www.photovoltaic-conference.com/ NOVEMBRO ICEECE 2015: Conferência Internacional sobre Energia, Meio Ambiente e Engenharia Química Data: 12/11/2015 a 13/11/2015 Local: Tokyo, Japão Site: http://www.waset.org/conference/2015/11/kyoto/ICEECE/call-forpapers <Destaque> Comitê Editorial Editorial Committee Presidente - President Geraldo Lúcio Tiago Filho - CERPCH/UNIFEI Editores Associados - Associated Publishers Adair Matins - UNCOMA - Argentina Alexander Gajic - University of Serbia Alexandre Kepler Soares - UFMT Ângelo Rezek - ISEE/UNIFEI Antônio Brasil Jr. - UnB Artur de Souza Moret - UNIR Augusto Nelson Carvalho Viana - IRN/UNIFEI Bernhard Pelikan - Bodenkultur Wien - Áustria Carlos Barreira Martines - UFMG Célio Bermann - IEE/USP Edmar Luiz Fagundes de Almeira - UFRJ Fernando Monteiro Figueiredo - UnB Frederico Mauad - USP Helder Queiroz Pinto Jr. - UFRJ Jaime Espinoza - USM - Chile José Carlos César Amorim - IME Marcelo Marques - IPH/UFRGS Marcos Aurélio V. de Freitas - COPPE/UFRJ Maria Inês Nogueira Alvarenga - IRN/UNIFEI Orlando Aníbal Audisio - UNCOMA - Argentina Osvaldo Livio Soliano Pereira - UNIFACS Regina Mambeli Barros - IRN/UNIFEI Zulcy de Souza - LHPCH/UNIFEI ONLINE UNIT MANAGEMENT FOR OPTIMAL OPERATION OF HYDRO POWER PLANTS.........................................................................3 E.c. Bortoni, G.s. Bastos, B. Kawkabani INDEX TEST AND BEST CAM CURVES DESIGN PROCEDURE FOR KAPLAN TURBINES..............................................................................8 João Gomes P. Jr., Diego H. Kawasaka HEAD LOSSES ANALYSIS IN SYMMETRICAL TRIFURCATIONS OF PENSTOCKS - HIGH PRESSURE PIPELINE SYSTEMS CFD ..................... C. A. Aguirre, R. G. Ramirez Camacho 11 A FEASIBILITY STUDY ON THE USE OF WIND TUNNEL EXPERIMENTS FOR HYDROKINETIC TURBINES ........................................ 15 M. M. Macias, R. C. F. Mendes, P. A. S. F. Silva, T. F. Oliveira, A. C. P. Brasil Junior IAHR DIVISION I: HYDRAULICS TECHNICAL COMMITTEE: HYDRAULIC MACHINERY AND SYSTEMS Classificação Qualis/Capes B5 B4 ENGENHARIAS I; III e IV Biodiversidade Interdisciplinar Áreas de: Recursos Hídricos Meio Ambiente Energias Renováveis e não Renováveis ISSN 1676022-0 A revista está indexada no DOI sob o prefixo 10.14268 ISSN 1676-0220 9 771676 022009 00064 ARTIGOS TÉCNICOS Comitê Diretor do CERPCH Director Committee CEMIG / FAPEPE / IEE-USP / FURNAS / IME / ELETROBRAS / ANEEL / MME TECHNICAL ARTICLES Technical Articles Seccion TECHNICAL ARTICLES ONLINE UNIT M ANAGEMENT FOR OPTIMAL OPERATION OF HYDRO POWER PLANTS ONLINE UNIT MANAGEMENT FOR OPTIMAL OPERATION OF HYDRO POWER PLANTS E.C. BORTONI, G.S. BASTOS, 2 B. KAWKABANI 1 ABSTRACT The paper presents a novel methodology for the operation of those hydro power plants provided with a single penstock by the optimal distribution of the dispatched power among its available generating units, aiming at the maximum efficiency of the whole power plant energy conversion. While previous optimization methods made use of off-line static curve and parameters or expensive flow meters, the proposed method is on-line in nature and uses a single pressure meter at the end of the power plant penstock. The method was applied to a power plant and has resulted in a higher efficiency operation under several conditions. KEYWORDS: Hydro power plants; energy; management. 1. INTRODUCTION 1.1 Classical economic dispatch Hydro power plants have been used for electricity generation for a long time due to its low operational cost, high energy conversion efficiency, and because it uses a renewable primary resource, the water. Nevertheless, water is an important resource that must be handled with care, to ensure long term sustainability. On the other hand, the self-sustainable development and the reasonable exploration of natural resources have become the great challenge of the 21st century. Hydro power plants deal with these two sides of the coin. In Brazil, where hydro power plants account for about 78% of the installed power and 92% of the gross energy generation, every tenth of a percent increase in the energy conversion efficiency is welcomed. In the design of a hydro power plant the gross head is defined by the regional topography and by the dam height. The total power and the number of generating units is a function of economic factors and of the hydrological availability of the site. The flexibility of hydro power plants allows its operation to accommodate both base and peak loads. When meeting the peak load the generated power must follow the load variations, therefore the loading and the number of employed units of the power plant must be chosen to provide the dispatched power with the highest efficiency. When supplying the base load all the available units are operated to generate their maximum power. Nevertheless, due to the hydrologic cycle, there is a percentage of the year, the dry season, when there is not sufficient water to push all the units of a power plant at their rated power and, again the available units must be dispatched to achieve the highest efficiency. Few papers cover the subject of optimal operation of a single hydro power plant (Arce et al., 2002), (Finardi and Silva, 2005), (Bortoni et al., 2007), and (Cheng et al., 2009). The great majority of published material regards to the hydro cascade operation, aiming at the maximum energy generation for a given inflow scenario such as (Pereira and Pinto, 1982) and (Carvalho, S. Soares, 1987). This paper presents a novel methodology the online optimal operation of hydro power plants for its best efficiency. As long as the efficiency of each generating unit is a function of the delivered power, the power plant optimization problem can be stated as defining the output of each unit that maximizes the total power generation efficiency or, in other words, to reach the minimum generation cost subject to system constraints to meet the demand and the capability of the machines. The simplest economic dispatch formulation is 2. OPTIMAL POWER PLANT OPERATION min CT (Pi) s.t. ΣPi = Pd (1) PLi ≤ Pi ≤ PUi. Notice that for hydropower plants, from now on, the cost function is considered as the water consumption as a function of the generated power, as long as the water has not a direct associated cost. 1.2 Dispatch based on efficiency tests Unfortunately, it is well-known that each machine, even from the same manufacturer and design, has its own characteristics and the generation cost will eventually vary between like units. Therefore, a procedure for optimal load distribution among the available units of a power plant can start from the presented equal load distribution criterion, as a quasi-optimal solution, to perform an iterative process based on the efficiency curve of each unit to obtain an overall maximum efficiency. In this case, field tests must be done to obtain the efficiency curve of each unit, which explains their efficiency behavior with the dispatched power under several operating conditions of head and flow. Fig. 1 presents an example of an operating chart of a hydro turbine model obtained from laboratory tests. The efficiency of the hydro turbine depends on the turbine flow and net head, leading to a three-dimensional diagram, which is the unit efficiency characteristic for any load and head conditions. Based on the knowledge of efficiency function of the units of a hydro power plant, it is possible to obtain an optimal solution that maximizes the efficiency of the entire power plant. There are many methods that can be used to obtain an optimal distribution of the dispatch power among the units of a power plant. A brief description of such methods is presented as follows. maxηT s.t. ΣPi = Pd PLi ≤ Pi ≤ PUi. (2) Universidade Federal de Itajubá, Brazil, e-mails: [email protected], [email protected] École Polytechnique Fédérale de Lausanne, Switzerland, e-mails: [email protected] 1 1 HIDRO&HYDRO: PCH NOTÍCIAS & SHP NEWS, 64 (5), JAN,MAR/2015, DA PÁG. 3-7 3 ARTIGOS TÉCNICOS With ηT given by: ONLINE UNIT MANAGEMENT FOR OPTIMAL OPERATION OF HYDRO POWER PLANTS Based on Figure 1 the net head is obtained as (5) (3) Fig. 2: Dimensions for the net head calculation. 3. PROPOSED OPTIMAL POWER PLANT DISPATCH Fig. 1: Operational chart of a hydro turbine. Nevertheless, this efficiency curve is a single picture of the machine behavior at a given moment and does not consider eventual variations on the machine or on the power plant parameters over time. Another approach based on loss minimization rather than efficiency maximization can be applied (Arce et al., 2002), but, again, the model parameters do not depend on machine aging, temperature variation and other factors. 1.3 Dispatch based on efficiency measurement The energy conversion efficiency is obtained by the ratio between the output and the input power. Equation (7) depicts this concept by including the related variables. (4) The net head is the difference between the gross head and the hydraulic losses. Therefore, a suitable device can be conceived to determine the online efficiency of each unit based or implemented using power plant SCADA. As long as the total efficiency of the power plant depends on the efficiency of each working unit (6), the optimization of the load distribution among the available units can be accomplished according to (5). 4 The previous methods have been implemented and tested for many years. While the first proposal is based on constant efficiency behavior, the latter is based on online efficiency measurement, which takes into account the aging of the units, penstock losses, tailrace level, and other variables. Nevertheless, the need for flow measurement constitutes a great drawback of the previous approaches. Online or off-line flow measurement in hydro power plants is a real challenge due to the large diameters involved and the required accuracy. Therefore, entire power plant efficiency optimization using flow measurement criteria falls on the high cost of flow sensors for such large diameters. In addition, occasionally the gain in efficiency with the optimal operation is smaller than the accuracy of the flow measurement, which leads to erroneous solutions. It is proposed that the described problems can be overcome by using a gauge pressure sensor at the end of the penstock, which has much lower cost and more accurate than flow sensors. The pressure at the penstock end is the difference between the gross head and the head losses, which is proportional to the squared flow. The following equation depicts this relationship. p0 = z – k · Q2(6) Equation (5) has a central importance in the adopted approach as long as it gives an alternative way to infer the influence of the flow without really measuring it. The static pressure at the end of the penstock is the gross head, which is the vertical distance from the forebay to the pressure metering point, minus the friction losses obtained through the head loss coefficient. One can conclude that the bigger the flow driven by the turbines, the lower the pressure at the end of the penstock will be. Therefore, maintaining the dispatched power met by the power generated by the power plant units, a reduction of the input flow means an increase in the overall power plant efficiency. In other words, according to (6), this flow reduction is related with a pressure increase. Therefore, instead of maximizing the overall efficiency in order to obtain a global optimum, the optimization problem can be rewritten to seek for the maximum penstock end pressure: HIDRO&HYDRO: PCH NOTÍCIAS & SHP NEWS, 64 (5), JAN,MAR/2015, DA PÁG. 3-7 ONLINE UNIT MANAGEMENT FOR OPTIMAL OPERATION OF HYDRO POWER PLANTS TECHNICAL ARTICLES max p0 s.t. ΣPi = Pd PLi ≤ Pi ≤ PUi. (7) The proposed methodology is suitable for those power plants with several units fed by a single penstock. The process starts with all the units equally loaded to meet the demanded power. Then, the loading of each unit is slightly changed until a maximum penstock end pressure is achieved. When applying this methodology the user does not have access to the overall efficiency value, since the flow is not measured. However, due to the concave characteristic of the efficiency curves, it is recognized that the system will work in a more economical way. The search algorithm must have a heuristic capable to direct the search engine to a power distribution between the available units that lead to the highest pressure and overall efficiency. Iteration is defined by a power step in the direction of the maximum positive pressure variation. The graphical results depicted in Fig. 4 exposes an interesting feature of the proposed combinatorial optimization methodology, i.e. the step changes when reaching the optimal solution, where backward steps to a previous more efficient stage and a reduction in the searching step as a function of an efficiency reduction, can be perceived. 3.1 REAL TIME OPTIMIZATION There are three important issues that must be taken into account when selecting the optimization method to solve the presented problem. The first is that the problem combinatorial in nature, there are infinity combinations of generated power among the available units that can meet the demanded power. The second is that there is not a formal mathematical model to be optimized, as long as updated efficiency curves of the units are not known, but only the information of the pressure at the penstock end. The third is that it is an online, real-time, optimization problem, which must be solved as fast as possible, maintaining the system stability. The developed algorithm considers the search as a combinatorial optimization problem (Nemhauser and Wolsey, 1998). The inputs of the model are the delivered power of each unit and the gauge pressure value at penstock end. The output is a signal to act as a reference on each speed governor and the power of each unit. Combinatorial optimization problems can be solved using either exact methods (Nemhauser and Wolsey, 1998) or heuristics (R. C. Holte, 2001). The exact methods explore large solution space and are very time consuming, making them impractical for real-time optimization applications. The use of heuristics is very suitable for such cases, allowing for finding efficient solutions in a very reasonable execution time instead of looking for the global optimum (R. C. Holte, 2001). The best solution search is made by applying combinations of small pre-defined disturbance steps in the generated power of each unit, keeping demanded power met, until the most efficient operation point is found. The example shown in Figure 3 represents a small power plant with three units and has a demand of 15 MW. At time 0, the demanded power is equally divided between the units, resulting in certain penstock end pressure. At time 1, the unit #1 has its power increased by one step, while unit #3 has its power reduced by one step, thus keeping the overall generated power and leading to a new pressure. By time 3, there is a new power distribution with a new step power increase in unit #1 and a reduction of the generated power of unit #2 by one step. The total generated power is kept constant and meets the dispatched power, with some change in the overall efficiency, described by the penstock end pressure. Fig. 3: Guess-and-check process of the search engine. Fig. 4: searching step change due to an efficiency reduction. The time to complete one iteration is approximately the units settling time multiplied by the number of possible combinations. The settling time depends on the power plant arrangement, which eventually will reflect the water acceleration time constant and on speed governor time constants. In general settling time is less than sixty seconds (Kundur, 1993). 4. APPLICATION As the first assumption, the proposed methodology is suitable for those power plants provided with a single penstock. Its application to the Rio Bonito Hydro Power Plant was selected to be explored here. This power plant has a single penstock feeding three units of 7 MW each, totalizing 21 MW. The rated gross head is 160 m and the rated flow is 15.6 m³/s. For evaluation purposes, off-line efficiency tests were applied to the three units in the wet and dry seasons of the year. Due to the absence of rain during the dry season in relation to the wet season, the gross head was reduced from to 158 m to 149 m. The efficiency curves of the machines are shown in Figure 5 for units #1, #2, and #3, respectively. The difference in the efficiency of the units for different gross heads is notorious, ranging from about 2 to more than 6 percentage points, reflecting the hydro turbine behavior represented by its performance chart. Such phenomenon is very difficult to model using algebraic formulations and can only be detected by using either on-line efficiency measurement or an observing variable. A very high accuracy class smart pressure sensor was installed at the penstock end. The digital transmission of the data allowed for obtaining pressure measurements with resolution on the order of millimeters of water column. For evaluation purposes, water flow was also measured with a non-intrusive ultrasonic flow meter. Figure 6 shows the penstock end pressure as a function of the water flow. Notice that the curve shows a negative coefficient parabola as expected (5) and that its abscissa intercept can vary according to the water upstream level. HIDRO&HYDRO: PCH NOTÍCIAS & SHP NEWS, 64 (5), JAN,MAR/2015, DA PÁG. 3-7 5 ARTIGOS TÉCNICOS ONLINE UNIT MANAGEMENT FOR OPTIMAL OPERATION OF HYDRO POWER PLANTS iterative process. A change of 500 kW is applied to the machines at each iteration. The best combination was obtained with machine #1 loaded with 6 MW and machine two with 4 MW. At this point the pressure was 144.890 mH2O and the flow was 9.62 m³/s. Figs. 7 and 8 presents these evolutions. The iterative process was considered finished as long as no combination was found better than the previous operating condition. A benefit of almost 1% was reached with the water flow reduction, as show in Fig. 9. 4.2 Dispatch of 18 MW (a) All the units were participating of the dispatch of 18 MW. In the beginning of the iterative process the load was equally divided by the three units and each one was loaded with 6 MW. After applying steps of 500 kW for each combination with the three available units. In the third iteration no combination was found better than the previous results, ending the iterative process, Fig. 12. (b) Fig. 7: Load distribution during the optimization process – 10 MW. (c) Fig. 5: Efficiency curves of units for different gross heads. Fig. 6: Water flow rate as a function of penstock end pressure. Fig. 8: Pressure and flow during the optimization process – 10 MW. Fig. 9: Efficiency evolution during the optimization process – 10 MW. Due to the very large time constant of the upstream water level, it is considered constant during the optimization process. Optimal load distribution among the three units of the power plant, employing the proposed methodology, was carried out for dispatched powers of 10 MW and 18 MW, for a gross head of 149 m. 4.1 Dispatch of 10 MW In the first case, dispatch of 10 MW, units #1 and #2 were selected to supply the load as long as each one is able to carry 7 MW. Each one was loaded with 5 MW at the beginning of the 6 Fig. 10: Load distribution during the optimization process = 18 MW. HIDRO&HYDRO: PCH NOTÍCIAS & SHP NEWS, 64 (5), JAN,MAR/2015, DA PÁG. 3-7 TECHNICAL ARTICLES ONLINE UNIT MANAGEMENT FOR OPTIMAL OPERATION OF HYDRO POWER PLANTS In addition, considerable improvement on the presented methodology can be obtained with the construction of a data base of efficient solutions, which would allow starting the iterative process from a quasi-optimal solution, reducing the number of steps and iterations. Therefore, future work includes, among others, the use of reinforced learning techniques and the study of online load distribution on those power plants provided with several penstocks. 6. NOMENCLATURE Fig. 11: Pressure and flow during the optimization process – 18 MW. Fig. 12: Efficiency evolution during the optimization process – 18 MW. 4.3 Analysis of the results In both dispatch conditions the combinatorial loading of the units was performed manually as a specific algorithm was not implemented in the power plant SCADA system. It was observed that the settling time was about thirty seconds for each combination and, therefore, each iteration was performed in less than five minutes. Considering a single step of 500 kW, the whole optimization process took two iterations to reach an efficient solution, i.e., less than ten minutes. Benefits of 0.9% and 0.3% of the operational efficiency were obtained with the application of the proposed methodology for dispatching 10 MW and 18 MW respectively. Such reduction could be expected because the greater the dispatched power the lower the flexibility of operation will be. At the limit, when dispatching 21 MW, the maximum output of the power plant, there is no flexibility, all the units must work on their rated power, and there is no choice, no gain. 5. CONCLUSIONS The work presented a novel methodology for the optimal operation of hydro power plants provided with a single penstock, leading to the optimal distribution of the dispatched power among its available units. As long as the flow is not measured, the efficiency of the power plant cannot be determined. However, due to the concave characteristic of the optimization function, the applied algorithm will search for the highest gradient in each iteration and the power plant will converge to its maximum efficiency. The presented application, for example, demonstrated gains that vary from zero, at full load operation, to 0.9% at half load. As long as the water availability varies during the year, establishing wet and dry seasons, the annual gain benefits can be assessed by mathematically operating the flow duration curve of the site under analysis with its gain-power curve. C P ΣPi η ρ g Q H p0 z k P1 γ D a y cost function ($) Subscripts power (MW) T total summation of all units generation (MW) d dispatched efficiency i i-th unit, input fluid density (kg/m³) L lower gravitational acceleration (m/s²) U upper turbine flow (m³/s) o output net head (m) static pressure (m) gross head (m) head loss coefficient pressure on the turbine input (N/m²) specific weight of the water (N/m³) the turbine input and output diameters (m) fixed distance between the turbine input to a given reference (m) variable distance from the reference to the downstream level (m) 7. REFERENCES • A. Arce, T. Ohishi and S. Soares. Optimal dispatch of generating units of the Itaipu hydroelectric plant. IEEE Trans. on PWRS-17(1), Feb. 2002, pp. 154-158. • E.C. Finardi, E.L. da Silva. Unit commitment of single hydroelectric plant. Electric Power Systems Research 75 (2005) 116-123. • E.C. Bortoni, G.S. Bastos, L.E. Souza. Optimal load distribution between units in a power plant. ISA Transactions 46, 2007, pp. 533–539. • C. Cheng, S. Liao, Z. Tang, M. Zhao. Comparison of particle swarm optimization and dynamic programming for large scale hydro unit load dispatch, Energy Conversion and Management, Vol. 50(12), Dec. 2009, pp. 3007-3014. • M.V.F. Pereira, L.M.V.G. Pinto. Decomposition approach to the economic dispatch of hydro-thermal systems. IEEE Trans. on PAS-101(10), 1982, pp. 3851-386 • M.F. Carvalho, S. Soares. An efficient hydro-thermal scheduling algorithm. IEEE Trans. on PWRS-2(3), 1987, pp. 537-542. • G. L. Nemhauser, and L. A. Wolsey. Integer and combinatorial optimization. Vol. 18. New York: Wiley, 1988. • R. C. Holte, "Combinatorial auctions, knapsack problems, and hill-climbing search." Advances in Artificial Intelligence. Springer Berlin Heidelberg, 2001. 57-66. • P. Kundur, Power System Stability and Control. EPRI Power System Engineering Series. McGraw-Hill, Inc. New York, 1993. ACKNOWLEDGMENTS The first author would like to thank FAPEMIG, CAPES, CNPq, FINEP, and INERGE for the support in conducting research. HIDRO&HYDRO: PCH NOTÍCIAS & SHP NEWS, 64 (5), JAN,MAR/2015, DA PÁG. 3-7 7 ARTIGOS TÉCNICOS INDEX TEST AND BEST CAM CURVES DESIGN PROCEDURE FOR KAPLAN TURBINES INDEX TEST AND BEST CAM CURVES DESIGN PROCEDURE FOR KAPLAN TURBINES 1 João Gomes P. Jr., Diego H. Kawasaka, 2 ABSTRACT This paper presents in detail the methodology adopted by the Alstom’s Special Measurements Team to perform an Index Test and define the best family of cam curves for its Kaplan turbines prototypes. The new methodology takes into account on-site head loss measurements and the shape of the turbine model’s cam curves in order to calculate a new family of cam curves for the prototype. Finally, this new family of curves is implemented on Alstom’s speed governor so that the generating unit will be at its best efficiency at any head. KEYWORDS: Kaplan Turbines; market;high efficiency; measurements. 1. INTRODUCTION 2.1 Initial Verifications Low head Kaplan and Bulb turbines have a very large market potential in Brazil. Differently from Francis turbines, Kaplan and Bulb turbines are double regulated, providing them high efficiency over a broad range of head and discharge. Nevertheless, their double regulation also means a more complex system which requires a very precise combination of guide vanes and blades positions in order to make sure these turbines are operating with their best efficiency. These blade-to-vane combinations, known as cam curves, are controlled by the speed governor as a function of the power setpoint and the measured head. The best cam curves are usually defined on reduced scaled model tests. Those are then loaded on the speed governor’s software of the prototype with the aim of reproducing the model results and maximize efficiency. Although, there are many factors that may decrease the prototype efficiency, such as: • The theoretical head loss estimative can be imprecise or different from the real loss due to modifications in the water intake or outlet. As the speed governor uses information of gross head, conversion from model test results using net head values to gross head must be as accurate as possible; • The head information sent to the prototype’s speed governor can be incorrect; • Non homologies between model and the prototype; • Commissioning errors on the speed governor, creating differences between the position set point indicated by the speed governor’s software and the real position of the guide vanes; • Damage or deterioration sustained from continuous use of the equipment can also cause inaccuracies. Most of the items above can be verified with an appropriate procedure to perform an index test. This paper presents these general procedures. In addition, as the index test is usually done in a small range of the operational head range of the generating unit, a detailed procedure to extrapolate cam curves to the remaining range of heads is presented. Some results obtained in units tested by the Alstom’s measurements team are presented as examples. Before performing the index test itself, it is recommended to make some initial verifications. One very important test is to verify if the head information sent to the speed governor is correct. There are usually two water level sensors, one upstream the turbine at the water intake and another downstream the turbine at the water outlet, that send these level measurements to the supervisory system (SCADA). The SCADA calculates the difference between those levels and sends this head information to the speed governor. Hence, it is very important to verify that these level measurements are correct. For that, one can measure the pressure at the turbine inlet p1 and calculate the upstream level H3 as given in eq.(1): 2. GENERAL PROCEDURES: INITIAL MEASUREMENTS AND INDEX TEST The index tests are usually required to follow the IEC 60041 standard (IEC:60041, 1991) procedures. On this chapter, some of these procedures are detailed and some other procedures are added. (1) Where z_1 is the pressure sensor level measured in meters above the sea level (masl). This level value must be as precise as possible, normally using topographical indications. The gravity g and the density ρ must be calculated as described in the IEC 60041 (IEC:60041, 1991). Or, at the turbine outlet: (2) From Alstom’s experience, the calculated upstream H_3 or downstream H_4 levels and the value indicated by the SCADA must not have more than 10cm difference. This variation is considered acceptable as there are measurements uncertainties in every term of the equations above, and the head information error will have a very small effect on the speed governor’s cam curves. Another very important verification that must be done before performing the index test is to make sure that the angle information of the blades and guide vanes indicated on the speed governor is indeed the real angle on the machine. As these information come from sensors and a mechanical system that can be damaged or modified with time and use, this check must be done from time to time. Another very important check regarding the speed governor itself is to certify that the error between the position setpoint of the blades or vanes and the real position are in agreement. The Alstom Hydro, Taubaté, Brazil,e-mail: [email protected] Alstom Hydro, Taubaté, Brazil,e-mail: [email protected] 1 2 8 HIDRO&HYDRO: PCH NOTÍCIAS & SHP NEWS, 64 (5), JAN,MAR/2015, DA PÁG. 8-14 TECHNICAL ARTICLES INDEX TEST AND BEST CAM CURVES DESIGN PROCEDURE FOR KAPLAN TURBINES closed-loop feedback system may have a steady-state offset error. The integrator part of the PID controller is meant to minimize this error, but during the real operation of the unit the operational error will depend on how the PID controller coefficients are set. In other words, before starting the index test and the best cam curve verifications, one must be sure that what is measured and informed to the speed governor of a double regulated turbine is indeed the real state of the machine. Otherwise, cam curves implemented on the speed governor that are based on scaled model results will not be effective. 2.2 Index Test and Cam Curve Verification The index test and cam curve verification will generate results such as the graph on figure 1. The procedure is: the blades are fixed and the guide vanes position is varied, while measuring efficiency for each combination. As the graph shows, there will be a combination of blades and vanes position that will maximize the unit’s efficiency. The general calculation and measurements procedures are well described at the IEC standard. Fig. 2: Example of head loss measurement as a function of the squared of the discharge. The blue points are the measured values and the red line is a tendency line of these points. The green line is the real head loss estimative. 3. GENERATING CAM CURVES FOR THE ENTIRE OPERATIONAL RANGE With the results obtained from one single index test, the Alstom’s special measurements team adapted the procedure proposed by Lee Sheldon (Sheldon, 2012) in order to extrapolate the best cam curve obtained from an index test to a set of 5 cam curves covering the whole operational range of the unit under test. From the graph on figure 1, one can define a combination of blades and guide vanes position that will maximize the unit’s efficiency. For this unit, the result would be those represented with the square dots on figure 3. On the figure 4, the variation of gross head for these measured points is shown. Instead of the value shown at the SCADA, the values presented were calculated using the measured discharge and the real head loss estimative, as described on item 1.3. Fig. 1: Efficiency measurements in order to find the best combination of blades and vanes position. The test is divided in steps where the blades positions are fixed while the vanes opening are varied. 2.3 Head Loss In addition to the efficiency, the index test can also provide a good estimative of the head loss coefficient. The net head Hn is calculated as given in the eq. (3): (3) The gross head HG is calculated as given in the eq. (4): HG = H3 - H4 (4) The head loss HL is then calculated: HL = HG - Hn(5) As discussed in 1.1, the upstream and downstream level measurements H3 and H4 displayed at the SCADA usually have an offset error if compared to the measurements done at the turbine inlet and outlet, as described in equations (1) and (2). As a consequence, the head loss calculated as in eq. (5) will not tend to zero when the discharge approaches zero. The figure 1 presents an example of head loss measurement. It presents the head loss measurements as a function of the square of the discharge. The red line is the tendency line of these points and shows how the measurements usually do not move towards zero due to the measurement errors explained before. Consequently, the real head loss is expected to be closer to the green line shown in the graph. Fig. 3: Best combination of guide vanes angles and blade angles obtained from the index test. The next step requires information from the model test. Using the model test hill chart, it is possible to draw lines of constant blade opening as a function of the gross head (figure 5). Scale model test results are usually given in net head values. The conversion to gross head must also be done with the head loss coefficient measured on-site. The method presented on this paper is based on graphical analysis and the idea of using scale model results is to visualize how the guide vanes should open or close as the gross head varies. Taking that in consideration, it is not important if there is a small variation between the best blade position measured on the scaled model test and the position measured on the prototype. The idea is to keep the same shape of the curves found on the model test in order to allow the extrapolation of the index test results to the whole head range. HIDRO&HYDRO: PCH NOTÍCIAS & SHP NEWS, 64 (5), JAN,MAR/2015, DA PÁG. 8-14 9 ARTIGOS TÉCNICOS INDEX TEST AND BEST CAM CURVES DESIGN PROCEDURE FOR KAPLAN TURBINES heads to cover the operational range of the unit. The graph on figure 6 defines 5 constant heads for this example: 11, 11.5, 12, 12.5 and 13 meters of water column. The triangles on the graph show the points where the constant blade angle curves cross these heads. As a result, 5 cam curves that will maximize the unit’s efficiency on any head are defined. They are presented on Figure 7. Fig. 4: Best measured guide vanes opening as a function of the measured head. The blue dots on figure 5 are the points where the constant blade opening curves cross the lines connecting the points measured on the index test. With the guide vanes opening values of these points, it is possible to find the equivalent blades opening on the graph of figure 3. Fig. 7: 5 cam curves covering the whole operational range. 4. CONCLUSION This paper presents some important steps that must be taken in order to perform an accurate index test followed to a procedure to extrapolate one single cam curve found on an index test to a set of 5 cam curves, covering the entire operational range of the unit. The measurements results obtained in one power plant in Brazil are presented. The resulting set of cam curves were implemented on the unit’s speed governor and are performing very well. 5. NOMENCLATURE Fig. 5: Plotting constant blade opening curves as a function of the gross head. Even though the shape of the curves is based on model test results, the blades angles are defined on the prototype’s index test. g Acceleration due to gravity HG Gross head HL Head Loss Hn Net head p Gauge pressure QDischarge υ Mean flow velocity zLevel ρ Density Subscritps 1 High pressure reference 2 Low pressure reference 3 Water intake reference 4 Water outlet reference 6. REFERENCES Fig. 6: Defining the blades angle and the vanes opening for 5 different heads. The Alstom’s speed governors have 5 cam curves for 5 different heads. Those curves are interpolated in between these 10 • IEC:60041. (1991). International Standard: Field acceptance tests to determine the hydraulic performance of hydraulic turbines, storage pumps and pump turbines. • Sheldon, L. (2012, March-April). Method to Delevop a Family of Cam Curves from a Single Index Test. HRW - Hydro Review Worldwide, pp. 40-45. HIDRO&HYDRO: PCH NOTÍCIAS & SHP NEWS, 64 (5), JAN,MAR/2015, DA PÁG. 8-14 TECHNICAL ARTICLES HEAD LOSSES ANALYSIS IN SYMMETRICAL TRIFURCATIONS OF PENSTOCKS - HIGH PRESSURE PIPELINE SYSTEMS CFD HEAD LOSSES ANALYSIS IN SYMMETRICAL TRIFURCATIONS OF PENSTOCKS - HIGH PRESSURE PIPELINE SYSTEMS CFD 1 C. A. Aguirre, R. G. Ramirez Camacho 2 ABSTRACT Systems using trifurcations allows flow of water to provide several turbines operating at the same time. This arrangement presents smaller assembly costs in comparison of independent pipeline systems. However this installation can generate high losses in the system. This study focuses the quantified losses as a function of the volumetric flow rate, using computational fluid dynamics (CFD). To determine the coefficient of losses were analyzed three mesh settings: hexahedral, tetrahedral and hybrid, considering steady state flow. Based on the literature, the k-ω turbulence model, with refinement near wall elements, quantified the y plus. Results of loss coefficients for different discretizations are presented in this paper. KEYWORDS: trifurcation, numerical simulation, SST, head loss, mesh. 1. EVALUATION OF MEASUREMENT UNCERTAINTIES The trifurcations are part of the architectural complex that forms the hydroelectric plant, which together with others, parts and equipment has the purpose to produce electricity using the hydraulic potential existing in a damming or a river. Whereas the optimal operating point of the pipeline systems, the losses must be reduced to obtain the best operating condition, with fields of stable flow. These conditions can be defined from tests in preliminary models to obtain appropriate geometries, with controlled load losses and variations of flow supplying the turbines. The analysis of head loss can be done in the laboratory or with the use of tools of numerical simulation with the advantage of analysis of the local flow with the real dimensions, allowing easy generation and adaptation of geometries. Considering its application, both approaches are complementary, meanings that the numerical validation must necessarily represent qualitatively or quantitatively, the experimental results. A lot of researches have been accomplished, in order to quantify the head losses in the pipeline systems of hydroelectric plants, focusing the best possible performance. Wanng Hua (1967) made an experimental analysis, with several wyes configurations and manifolds (Figure 1). The effects of roughness on the wall were not considered, once the pipe surfaces were polished. The head losses in the dimensionless form were quantified with relation to the average flow velocity in the main pipe. Based on the one-dimensional energy equation results were obtained using data acquisition systems such as; dynamic pressure that is representative of the flow in a particular section of pipe, the pressure reading using a catheter was inserted at a position and height where the flow is irrotational and permanent. Fig. 1: Component of the critical section of wyes and manifolds, top view. Rk Malik and Paras Paudel (2009) did an analysis for a small hydroelectric power plant of 3.2 MW, located in Kaski (Nepal). The constraints due the available space and the position of the turbines were considered for the design of the adduction system of the trifurcation, several tests were made focusing the optimal profile of trifurcation so the head losses are as low as possible. The calculations of pressure losses were done using the energy equation between the entrance and three exits simultaneously. The turbulent and laminar regimes were analyzed using ANSYS CFD-FLOTRAN. Besides a tetrahedral mesh was generate, as shown in Figure 2. The boundary conditions were defined considering at the entrance, the gauge inlet pressure of 177 mmH2O, and the speed between 3 and 4 m/s and the static pressure at the outlet is equal to the local atmospheric pressure. Fig. 2: Tetrahedral mesh of the trifurcation in the section of the flow separation. Changes in the geometry of the trifurcation were made to get to a head loss of 0.42%. Hence twenty different configurations of the trifurcations were tested, including mechanical stresses analyses. Sirajuddin Ahmed (1965) obtained results of the head loss in laboratory using three conventional configurations of the bifurcations in which was changed the angle between the branches from 60° to 90°, and the angle of taper for both 60°. Besides, the evaluations for two spherical bifurcations with angle between the branches of 90° and with different sphere diameters were checked. During the tests, the field of turbulent flow with Reynolds number between 5x105 and 3.75x105 and a maximum flow rate of 0.92 cfs (0.03 m3/s) were defined. The head loss coefficients for spherical bifurcations were higher than the bifurcations taper, the values of the first is 0.44 related to the bifurcation with the greater diameter sphere and 0.30 to the bifurcation with the smaller diameter sphere. The loss coefficients for the taper Instituto de Engenharia Mecânica, Universidade federal de Itajubá. Caixa Postal: 50 - CEP: 37500 903 - Itajubá – MG Brasil. Av. BPS 1303, Bairro Pinheirinho, e-mail: [email protected] Instituto de Engenharia Mecânica, Universidade federal de Itajubá. Caixa Postal: 50 - CEP: 37500 903 - Itajubá – MG Brasil. Av. BPS 1303, Bairro Pinheirinho, e-mail: [email protected] 1 2 HIDRO&HYDRO: PCH NOTÍCIAS & SHP NEWS, 64 (5), JAN,MAR/2015, DA PÁG. 8-14 11 ARTIGOS TÉCNICOS bifurcations are 0.16 for the 90° angle between the branches and 0.08 to 0.088 for angles of 60°. These results are for a symmetrical flow at the entrance of the bifurcation. Buntić Ivana, Helmrich Thomas and Ruprecht Albert (2005) presented a model of Very Large Eddy Simulations (VLES). This model has an adaptive filter technique that separate the part of the fluid resolved numerically and the modeled part (Figure 3). The modeled parts use k-ε extended model of Chen and Kim. This model VLES is applied to simulate flows with unstable vortices in geometries where the turbulent flow cannot be performed with the classical models of turbulence. HEAD LOSSES ANALYSIS IN SYMMETRICAL TRIFURCATIONS OF PENSTOCKS - HIGH PRESSURE PIPELINE SYSTEMS CFD Equation of conservation of mass (1) The equation of conservation of momentum, considering the steady flow and inertial system. (2) Generally the term of the turbulence and the viscous tensor are grouped. Thus the overall or general tensor is represented by. (3) Fig. 3: Model Approach VLES Moreover, this model tries to maintain the computational efficiency of the Reynolds-Average Navier-Stokes (RANS) and the potential for solving large turbulence structures of the Large Eddy Simulation (LES). Although the model can be applied in coarse meshes the simulation depends heavily on the modeling. Additionally, Buntić Ivana, Helmrich Thomas and Ruprecht Albert (2005) had performed the simulation of a spherical trifurcation, Figure 4, which makes the distribution of water from the adduction system of water until the turbines. The outer branches present oscillations given by the vortices found in the flow. The variations are not periodic of a branch to another generating a high head loss. The Reynolds tensor τt can be modeled appropriately using the Boussinesq hypothesis presented in terms of turbulent viscosity µt. (4) Where k is the kinetic energy and δij is the Kronecker delta operator. In this paper the turbulent viscosity is obtained using the SST turbulence model that uses the hypothesis of Boussinesq. 3. METHODOLOGY The geometry of the trifurcation used in the research was provided by ALSTOM Figure 5. This model has 25 m wide, 7 m high and 39 m long. The pipe diameter into the fluid inlet (water 20° C) is 4.5 m and on all outputs 3 m, and in the trifurcation the approximate angle of the side branches are 60 degrees. Fig. 4: Trifurcation - computational mesh. 2. MATHEMATICAL MODEL Turbulent flows are characterized by transport of the large quantities of mass and momentum scalar that floating in the time and the space, not steady. The flow velocity and fluid properties have random variations in different spectrum ranges. 2.1 Equations for turbulent flow The ANSYS-CFX software uses the equations of Reynolds (Reynolds Averaged Navier-Stokes RANS) to solve the problems of turbulent flow. In this model all dependent variables, scalars and vector are decomposed into a temporal average and a fluctuating part, when these variables are introduced in the conservation equation for not inertial systems results, as shown following equations. 12 Fig. 5: General geometry of trifurcation. Flow rates are measured within the range from 20 m3/s to 70 m3/s, which still shows a permanent flow. Considering the dimensions and flow rates, the Reynolds number is approximately 2.014x10-7 As (Casartelli et al., 2010) and (Galarça et al., 2004), show that with a high Reynolds number and a complex geometry, the SST turbulence model can be applied, since this model can solve the problems of the models k-ω and k-ε. Thus, in regions with bends and nearby the wall is used the k-ω model, and regions farther from the wall the k-ε model. The SST model based on the k-ω considers the transport of turbulent shear stresses and provides accurate flow predictions for cases with adverse pressure gradients involving separation. HIDRO&HYDRO: PCH NOTÍCIAS & SHP NEWS, 64 (5), JAN,MAR/2015, DA PÁG. 8-14 HEAD LOSSES ANALYSIS IN SYMMETRICAL TRIFURCATIONS OF PENSTOCKS - HIGH PRESSURE PIPELINE SYSTEMS CFD TECHNICAL ARTICLES Moreover, the mesh generation requires the definition of the value of refinement of elements near the walls which can be done using an appropriated wall function “y”, Ariff (2009) shows how can obtain this value associated with the minimum y+ that can be applied to the problem and the turbulence model. Casartelli (2010) defines the y+ range for adduction pipeline of a turbine, working with the turbulence model k-ω SST are between 200 and 500 because the model applies equations in the boundary layer. Thereby, this case using the y+ of 300 defines a minimum distance for the initial layer of the mesh equal to 1.95x10-3 m. The present work adopts ICEM-CFD® for preprocessing and generation of geometry and mesh. The geometry uses three composite meshes of different geometric elements inside it and near the surface. The main characteristics of the meshes showed in Table 1 and in Figure 7. The first mesh is hexahedral originated of approximately 400 blocs (Figure 6) with hexahedral refinement and exponential growth near the walls. The second mesh is composed of tetrahedrons and pyramids at the core and with layers of prisms with linear growth on the walls. The third mesh is composed of hexahedral and pyramids at the core and in the walls prism with linear growth. Table1: General characteristics of meshes. Mesh Number of elements Mesh type Hexahedral 7006388 Structured Tetrahedral 4154711 Unstructured Hexahedral core 2272218 Unstructured Fig. 7: Cutting Plane and behavior of the surface layers of mesh refinement for (a) hexahedral, (b) tetrahedral and (c) hybridize with hexahedral core. With the range of mass flow rates, SST turbulence model and mesh generated, the "solver" software ANSYS-CFX ® is chosen for the numerical solution of the problem. The value of convergence RMS (root mean square) is fixed at 1x10-4 according to the values given by ANSYS CFX Solver theory guide (2012) for engineering researches and the ten points to be evaluated inside the range of volumetric flows are shown in Table 2. The boundary conditions for the entrance and exit are respectively mass flow and static pressure. 4. RESULTS The velocity and pressure data obtained with the ANSYS-CFX program are used to calculate the head loss of each branch of the trifurcation, as shown by (Wang et al., 1967) who employs the equation 5, based on the dynamic pressure of the main pipeline for the calculation of the coefficient of head loss k. (5) Where pT(r,c,l), corresponds to the values of total pressure in the branches, right, center and left, vinlet, is the reference flow velocity at the entrance of the pipe. Table 2: Coefficient of head losses of trifurcation given by the numerical approach, considering meshes with hexahedral and tetrahedral elements and hybrid mesh with hexahedral core. Coefficient of head losses k Volumetric flow rate Q [m3/s] Fig. 6: Construction of blocs of hexahedral mesh isometric view (a), union of the four pipes (b) and views of the blocs that make up the cross section of the pipeline (c). In the Figure 7 (a) shows the influence of mesh refinement near the wall with the number of elements because the refinement extends to the inside of the mesh where is not very useful, while the unstructured grids (b) and (c) present refinement only in the layers nearest to the surface reducing the number of mesh elements. Left branch Center branch Mesh Mesh Right branch Mesh Hexa Tetra Core Hexa Tetra Core Hexa Tetra Core 20 0.513 0.442 0.444 0.329 0.268 0.265 0.515 0.429 0.431 25 0.456 0.424 0.423 0.279 0.252 0.252 0.457 0.415 0.412 30 0.448 0.415 0.409 0.258 0.238 0.237 0.443 0.403 0.403 35 0.446 0.406 0.404 0.252 0.228 0.228 0.442 0.397 0.399 40 0.426 0.400 0.405 0.245 0.220 0.214 0.423 0.386 0.389 45 0.430 0.396 0.397 0.242 0.213 0.215 0.442 0.377 0.391 50 0.424 0.389 0.400 0.234 0.208 0.206 0.446 0.374 0.373 55 0.423 0.394 0.403 0.231 0.201 0.204 0.429 0.373 0.373 60 0.426 0.383 0.397 0.223 0.198 0.200 0.402 0.362 0.372 65 0.435 0.388 0.392 0.220 0.194 0.198 0.433 0.368 0.372 HIDRO&HYDRO: PCH NOTÍCIAS & SHP NEWS, 64 (5), JAN,MAR/2015, DA PÁG. 8-14 13 ARTIGOS TÉCNICOS In Figure 8 a, b, c are represented the losses coefficients of the three branches of the trifurcation as a function of volumetric flow rate. Three mesh configurations were analyzed: hexahedral (black line), tetrahedral with elements prismatic in the wall (blue line) and hexahedral core (red line). In all Figures 8 a, b, c, the analysis shows that the hexahedral mesh has higher values when is compared to the unstructured meshes. More specifically, in the Figures 8 a, b the hexahedral mesh has greater instability of the loss coefficient, compared to unstructured meshes. However, it shows that the unstructured meshes have similar behaviors, especially in the relation to head loss on the central branch. These figures show that the smaller loss values are close to the nominal flow rate, 90 m3/s. However, the analysis around this value requires an approach using transient models type URANS or LES. In this range, considering the phenomenon in the steady state, the desired value of convergence can be reached with SST (RANS) model. The central branch presents head loss coefficients smaller, because only have change in the area of pipes due to the greater effect of energy dissipation is associated with the viscous friction at the wall, whereas the side branches have variation in crosssectional area and a strong change in the direction of flow (secondary flow). The trifurcation at the nominal condition, generally operates with flow rates above 60 m3/s in the transient regimen where the coefficients for the central and lateral branches are around 0.2 and 0.4 respectively (Figures 8 a, b, c). Mays et al. (1997) recommends for symmetric trifurcations the value of 0.3 in the loss coefficient, for the three branches. HEAD LOSSES ANALYSIS IN SYMMETRICAL TRIFURCATIONS OF PENSTOCKS - HIGH PRESSURE PIPELINE SYSTEMS CFD Fig. 9: Streamlines along the trifurcation of the hexahedral mesh (a), tetrahedral mesh (b) and hybridizes with hexahedral core mesh (c). 5. CONCLUSIONS An analysis using Computational Fluid Dynamics CFD was presented to determine the losses coefficients in adduction systems of type "symmetric trifurcation". The geometry was divided into structured and unstructured volumetric elements. Additionally, other analysis was done in relation to the velocity field, the trajectories of the streamlines checking variations when using different discretizations. Apparently the hexahedral mesh is more sensitive to quantify the head losses meanwhile the unstructured meshes show similar behavior between them and qualitatively with the hexahedral mesh. Therefore, it is necessary that the results are validated comparing its results with reduced model tests in specialized laboratories. 6. BIBLIOGRAPHY Fig. 8: Head loss coefficients of the three meshes and left (a) right (b) and central (c) branches. The behavior of the streamlines given by the velocity field show clear differences between structured and unstructured mesh as show in Figure 9, where structured meshes capture a formation and propagation of vortexes in the side branches larger than structured mesh and the velocities along the streamlines and the separation of the boundary layer are higher for the hexahedral mesh. The hexahedral mesh in all flow rates were studied always reached the value of converge with fewer iterations than the unstructured grids. The differences in the number of iterations are between 50% and 70% less for the hexahedral mesh. Besides, comparing these meshes in relation to the number of iterations, the hexahedral mesh requires a minimal convergence value, but the tetrahedral mesh converges faster. 14 • ANSYS, Inc. Southpointe, 2012, ANSYS CFX-Solver Theory Guide, Canonsburg, PA, USA. • Ariff M., Salim S. M., CHEAH S. C., 2009, Wall y+ approach for dealing with turbulent flow over a surface mounted cube: part 1 – low Reynolds number, Seventh International Conference on CFD in the Minerals and Process Industries CSIRO, Melbourne, Australia. • Buntić I., Helmrich T., Ruprecht A., 2005, Very large eddy simulation for swirling flows with application in hydraulic machinery, Scientific Bulletin of the Politehnica University of Timisoara Transactions on Mechanics Special issue, Timisoara, Romania. • Casartelli E., Ledergerber N., 2010, Aspects of the numerical simulation for the flow in penstocks, IGHEM-2010, Roorkee. India. • Galarça, M. M., 2004, Análise numérica para modelos de turbulência κ-ω e SST/κ-ω para o escoamento de ar no interior de uma lareira de pequeno porte, Programa de pósgraduação em Engenharia Mecânica – PROMEC, Universidade Federal do Rio Grande do Sul – UFRGS. • Mays L. W., 1997, Hydraulic design handbook, Editorial McGraw-Hill Education, New York, USA. • RK, M., Paras, P., 2009, Flow modeling of the first trifurcation made in Nepal, Hydro Nepal, Kathmandu, Nepal. • Sirajuddin A., 1965, Head loss in symmetrical bifurcations, The University of British Columbia, Vancouver, Canada. • Wang H., 1967, Head losses resulting from flow through wyes and manifolds, The University of British Columbia, Vancouver, Canada. ACKNOWLEDGMENT The author acknowledges to ALSTOM Brasil Energia Transporte for financial and technical support HIDRO&HYDRO: PCH NOTÍCIAS & SHP NEWS, 64 (5), JAN,MAR/2015, DA PÁG. 8-14 TECHNICAL ARTICLES A FEASIBILITY STUDY ON THE USE OF WIND TUNNEL EXPERIMENTS FOR HYDROKINETIC TURBINES A FEASIBILITY STUDY ON THE USE OF WIND TUNNEL EXPERIMENTS FOR HYDROKINETIC TURBINES 1 M. M. Macias, R. C. F. Mendes, 2P. A. S. F. Silva, 2 T. F. Oliveira, 2A. C. P. Brasil Junior 2 ABSTRACT An experimental methodology to assess the performance of axial hydrokinetic turbines, based in wind tunnel experiments, is presented in the present paper. The goal is to propose an experimental approach using airflow and reduced scale models in order to evaluate a real axial turbine running in water flow conditions. Scaling arguments had shown that it is possible to obtain dimensionless performance parameter under a set of similarity conditions (geometrical, kinematical and dynamical) using air flow and, at last, to transpose the model results to the prototype real scale in water flow. Experimental results for the power coefficient as a function of the tip speed ratio are presented for a 1:23 model. The prototype is a three blade axial rotor hydrokinetic turbine, with 10m of diameter, designed to produce 500 kW. The control of the rotation velocity of the rotor arises as a key element of the methodology. The experiments were carried out in a wind tunnel facility for a range of undisturbed velocities between 6m/s and 15m/s. Comparisons with numerical results from 3D RANS simulations are made to evaluate the limits of application of the methodology. KEYWORDS: Hydrokinetic turbines, reduced (small) scale experiments, hydrodynamics of axial turbines.. 1. INTRODUCTION In reason of economic and populational growth, the energy consumption has steadily increased. The projection for consumption by the year 2030 is more than twice the amount of energy consumed in 1980. This growth scenario leads to a search for sources of clean and renewable energies with low environmental impact (Kaygusuz and Güney, 2010). The hydrokinetic energy is an emerging class of renewable technology that is being widely recognized as a unique and unconventional solution to the use of water resources (Khan, Bhuyan, Quaicoe and Iqbal, 2009). The hydrokinetic energy conversion process involves the use the kinetic energy contained in any water flow, which may be the source of drive seas or even the normal flow of a river. The term hydrokinetic turbine is dedicated to hydraulic machines capable of converting kinetic energy from rivers or ocean currents into electricity (Lula, Brazil, Salomon, Walnut and Maruzewski-Gaud, 2006). Different from one conventional hydroelectric power plant, the process of using hydrokinetic energy does not require the construction of a dam, it is only necessary a submerged turbine capable of converting kinetic energy contained in the water stream into shaft work able to activate the generator, allowing the conversion into electricity. Thus one need not interfere with the natural course of the river. However, the hydrokinetic system has lower efficiency, limited to 59.3% of kinetic energy incident on the turbine rotor (Betz, 1926). There are few references in the technical literature on the design and use of hydrokinetic turbines, and also the knowledge available in this application area is restricted. Generally, this type of turbine is derived from the wind turbines, since the operation of both are similar. This paper presents an experimental and numerical study of a small scale hydrokinetic turbine tested in wind tunnel. The prototype is a 10 meter diameter axial hydrokinetic turbine with three blades, designed to use the remaining potential of a hydro power plant and generate 500kW. The scaling factor between the prototype and the model is 1:23. The study of the scale model is important because the prototype is a complex machine, with it one can predict phenomena that will occur during operation of the turbine, thus avoiding possible failures. The study model is also used to find the best conditions for prototype work. For the construction and testing of a scale model is important to follow the theory of similarity. This ensures that the prototype and the model will have their similar characteristics, thus validating the test. The similarity theory says that one machine will be similar to your model only if they have the three possible types of homogeneities: dimensional, kinematics and dynamics (White, 2011). A prototype and a scale model are geometrically similar if only all the dimensions of the body in three coordinates have the same ratio of linear scale. The kinematic similarity requires the prototype and the model have the same ratio of length scale and time. The result is that the speed scale will be the same for both. In flow machines, it is possible to association the kinematic similarity with the triangles of velocities. To maintain the similarity of triangles speed is necessary that the model preserves the tip speed ratio from the prototype(λmodel = λprototype ). The dynamic similarity exists when the model and the prototype have the same reasons of scale length, time and strength. With the dynamic homogeneity, it is possible to find a relation between the potencies. This relationship can be presented by the power coefficient (Cpmodel = Cpprototype) (White, 2011). This paper presents a methodology for a scale model of hydrokinetic turbine tested in wind tunnel. It is intended to find the performance of the turbine through the curves of Cp versus λ. The results will be compared with the numerical results of a 3D RANS simulation. 2. EXPERIEMENTAL METHODOLOGY 2.1 Wind tunnel The tests were conducted in an open loop wind tunnel from the Laboratory of Fluid Mechanics, Department of Mechanical Engineering, University of Brasilia (UNB). The dimensions of the test section are 0,65x0,65 m and the tunnel extension is 10m . The fan is located at the exit of the tunnel and is driven by an electric motor of 40 hp, sucking air from the tunnel entrance to the exit. The possible variation of the speed free flowing between is 6 and 16 m/s. The boundary layer into the section test, where Universidade de Brasília. Departamento de Engenharia Mecânica. Laboratório de Energia e Ambiente. 70910-900. Brasília, DF. BRAZIL, e-mail: [email protected] Universidade de Brasília. Departamento de Engenharia Mecânica. Laboratório de Energia e Ambiente. 70910-900. Brasília, DF. BRAZIL. 1 2 HIDRO&HYDRO: PCH NOTÍCIAS & SHP NEWS, 64 (5), JAN,MAR/2015, DA PÁG. 15-19 15 ARTIGOS TÉCNICOS the turbine is positioned, is of 20 mm and the level of turbulence in the tunnel is less than 5%. The wind speed is measured using a Pitot tube connected to a manometer. The pitot tube is located 3.6 m from the tunnel entrance and at 1.4 m from the model and in the middle of the cross section. The model is placed in the test section of the tunnel and at a distance of 5.0 m from the entrance center. The experimental error in the measured flow velocity is estimated at 5%. In Fig.1 is shown an image of the turbine within the wind tunnel during a test. A FEASIBILITY STUDY ON THE USE OF WIND TUNNEL EXPERIMENTS FOR HYDROKINETIC TURBINES on the motor through a series of variable resistors. Maintaining a constant flow speed for each speed of rotation of the torque obtained from the model system was measured with the load cell. The signals obtained by the rotation sensor and the load cell was sent to the microcontroller Arduino for automation of the assay. Fig. 2: Details of sensors Fig. 1: Scale model into wind tunnel To analyze the performance of the turbine curves λ versus Cp and Cq are constructed versus λ, and the power coefficient Cp, Cq torque coefficient λ and the ratio of blade tip speed. These are determined by eq. (1), (2) and (3). The speed ratio is the speed ratio between the farthest point on the rotor blade and the speed of free-flowing. 2.2 Scale model The model hydrokinetic turbine was built with a scale factor 1:23 using the same geometric details of the prototype. The model has diameter 520 mm and dimensions of the rest remains the same scale factor. The turbine is of the horizontal axis type rotor with three blades. The profiles of the vanes are NACA type 65(3)618. The model was built from aluminum using a CNC machine three axes. The rotor blades are attached directly to the shaft of a DC permanent magnet motor Electro-Craft 110W. To apply load on the rotor, a DC motor was connect in the shaft working as a brake. The electric motor is integrated in a circuit of variable resistors, working as a brake and as a variable load that can control the rotational speed of the turbine. The motor is supported on two ball bearings set in such structure that supports the turbine system. Therefore, the brake balance was in order to measure the torque of the system directly from a load cell. The load cell was constructed with a digital scale SensorDisc SF-400. The transmission of force between the brake and the balance is carried by an arm fixed to the metal brake, as can be seen in Fig.2. Load cell was calibrated using a system known weights. The torque is calculated as the product of the force measured in the load times the distance from the cell axis by the end of the arm. The typical error in the measurement of torque is less than 0.01 N cm. The rotation speed of the rotor is measured with an inductive speed sensor SCHMERSAL IFL3B-10E-8M. The rotation sensor was used measuring the rotational frequency of the shaft turbine. This sensor was calibrated using an oscilloscope. The data acquisition was performed using the open source microcontroller Arduino Leonardo. The circuits of the sensors were integrated on a single card and controlled via the Arduino board. The tests of the reduced model were performed for different free flow speeds. Wind speeds were adjusted values 13,14 e 15 m/s. These speeds were measured by the Pitot tube and manometer. For each average flow velocity of the rotational speed of the turbine is controlled and gauged with the inductive rotation sensor. Speed control is accomplished by applying load 16 (1) (2) (3) In the above equations, P is the power in the brake shaft, E_0 is the energy contained in the flow area of the turbine housing (hydrokinetic power from the free stream), ρ is the density of air and A = (πr2)⁄2 corresponds to the area perpendicular to the flow of the turbine inlet section. The angular velocity ω is the rotor radius is r and U∞ is the speed of free-flowing. The shaft power can be determined by: P = τ ω (4) where τ is the torque on the shaft which is determined by the product of the force measured by the load cell times the size of the arm. 3. NUMERICAL CALCULATION The three-dimensional model was generated on SOLIDWORKS software based on the design characteristics of the reduced model. The software used for generating numerical grid was ANSYS ICEM CFD. The computational domain was divided into two parts: an inner, rotatable, with high density of elements and an outer stationary with low density elements. The rotating field is shaped like a cylinder 0.3 meters radius and 0.1 meters long. Already the stationary domain is shaped like a cube, which contains the rotating field with the approximate dimensions of the wind tunnel with section 0.65 meters tall and wide and 2 feet deep in the face of affluence and 6 meters downstream as can be observed in Fig. 3. HIDRO&HYDRO: PCH NOTÍCIAS & SHP NEWS, 64 (5), JAN,MAR/2015, DA PÁG. 15-19 A FEASIBILITY STUDY ON THE USE OF WIND TUNNEL EXPERIMENTS FOR HYDROKINETIC TURBINES TECHNICAL ARTICLES Fig. 3: Numerical domain The numerical grid generated showed 2.51 x 106 us, with great refinement in the region close to the wall next regions. The turbulence model used in this modeling was the SST, known for showing good results for both laminar flow sublayer as in free stream. To this end, the treatment was made close to the wall so that the values of y + 2 are smaller than Another important factor is the mesh refinement near the mat due to the high velocity gradient in this region as illustrated in Fig.4. In Fig.6 the power coefficient for various velocities of free flow is presented. It can be seen that the maximum value of Cp is around 0.11 and is obtained for λ = 3.8 and a free-flow speed of 13 m/s. For speeds 14:15 m / s the maximum value of Cp is at λ = 3.2. All experimental curves were fitted by a third-order polynomial. In Fig.7 the coefficient of torque for various free flow speeds is presented. It can be seen that the maximum value is obtained Cq for λ = 2.9 and a free-flow speed of 13 m/s. For speeds 14:15 m / s the maximum value of Cp is at λ = 2.6. Fig. 4: Numerical mesh The mesh is imported into CFX and then the boundary conditions are applied in the computational domain as shown in Fig 5 Attempted to perform with maximum fidelity of the experiment in wind tunnel. • Input speed: is a Dirichlet boundary condition, which is attributed to the constant fluid velocity and normal to face with turbulence intensity of 5%, according to the experimental conditions. Already the pressure is determined so as to satisfy the equations of motion. • Outlet pressure: the downstream face a condition of Dirichlet, which defined the boundary condition as the atmospheric pressure (101325 Pa) and consequently the velocity field is determined by the equation of motion was applied. • No Slip: was imposed on all solid components of the rotor, this means that the relative velocity of the fluid particle in the wall to the wall is zero. • Free slip: was imposed on the walls of the tunnel, so that does not influence the flow. Thus, the shear stress between the tunnel wall and the fluid is zero. • Interface: The internal surfaces defining the cylindrical rotary connection between the subdomain that contains the rotor and the stationary field, have been linked, the condition of frozen rotor ("rotor Frozen"). Thus the components of the fixed domain are transformed into a moving reference system, adding the Coriolis and centrifugal acceleration, enabling local flow characteristics are transported through the interface. Fig. 5: Contour conditions 4. RESULTS AND DISCUSSIONS The rotor performance was evaluated for three speeds of the wind tunnel: 13; 14:15 m / s. For each speed, the brake applied was varied and the torque and speed mesurados rotation, allowing the calculation of the coefficient of power and coefficient of torque. Cp and Cq versus λ versus λ curves are shown in Figures below. Fig. 6: Experimental curve: Cp x lambda Fig. 7: Experimental curve: Cq x lambda The Fig.8 shows the comparison of the experimental and numerical case for the speed of 13m / s tunnel. How widely studied in the literature, in studies such as Muljadi et al. (1999) and Burton et al. (2001), the variation of the pitch angle is a direct effect on the power converted by the turbine. The manual assembly process and the small size of the model contribute significantly to the occurrence of unwanted pitch angles, since this displacement of about 0.17 mm in the positioning of the blade axis represents a one degree change in pitch angle. Thus, it is believed that the discrepancies found between the numerical and experimental results shown in Fig. 8 is related to incorrect assembly or even the instrumental error in the manufacturing process of the blade, which are ignored in the numerical modeling. However this uncertainty still needs further investigation in metrological and numerical studies. HIDRO&HYDRO: PCH NOTÍCIAS & SHP NEWS, 64 (5), JAN,MAR/2015, DA PÁG. 15-19 17 ARTIGOS TÉCNICOS A FEASIBILITY STUDY ON THE USE OF WIND TUNNEL EXPERIMENTS FOR HYDROKINETIC TURBINES the prototype show significant differences in the values of power coefficient for similar values of λ While the similarity in the values of λ, which ensure proportionality in the forces acting on the blade, the Reynolds number the prototype comes to submit two orders of magnitude greater than the reduced model magnitude, being reduced in 4x105 and 2.2 x 106 in the prototype model. This difference has a major influence on the flow dynamics, which in turn interferes with the power values. 5. CONCLUSIONS Fig. 8: Numerical and experimental points for 13 m/s The t of the maximum power value of 0.11 was obtained for the experimentally reduced to a free-flow speed of 13 m / s model. The speed ratio corresponding to peak power coefficient is around the value of 3.8. The experimental results of this study allow to obtain the characteristics of the reduced model of hydrokinetic turbines in various operating conditions. For translating the results of the model to the prototype further investigation due to the large difference in Reynolds number, thus having a hard time to transpose results is necessary. Besides deepening the errors involved in assembling the experimental test. 6. NOMENCLATURE A Rotor area [m2] Cp Coefficient of potency Cq Coefficient of torque E0 Hydrokinetic potency [W] P Potency[W] r Rotor radius [m] U∞ Flow velocity [m/s] λ Tip speed ratio ρ Specific mass [kg/m3] τ Torque [N.m] ω Rotational speed [rad/s] 7. REFERENCES Fig. 9: difference of power caused by the angle of the blade. (Burton et al., 2001) Fig. 10: Numerical comparison between prototype and scale model Applying a method similar to the scale model, the prototype of hydrokinetic turbines have been numerically simulated in real scale to a wide range of values of λ as shown in Fig. \ Ref {} prototype. We note that the reduced model in air and water in 18 • A. Betz. Wind energy und ihre ausnutzung durch windmuehlen. 1926. • Tony Burton, David Sharpe, Nick Jenkins, and Ervin Bossanyi. Wind energy handbook. 2001. • M. Güney and K. Kaygusuz. Hydrokinetic energy conversion systems: A technology status review. Renewable and Sustainable Energy Reviews, pages 2996–3004, 2010. • M.J. Khan, G. Bhuyan, M.T. Iqbal, and J.E. Quaicoe. Hydrokinetic energy conversion systems and assessment of horizontal and vertical axis turbines for river and tidal applications:A technology status review. Applied Energy, 86(10):1823 – 1835, 2009. • Flavio A.C.M. Lula, Antonio C. P. Brasil Junior, Lucio B.R. Salomon, Ricardo Noguera, and Pierre Maruzewski-Gaud. Experimental study of a new design of hydrokinetic turbine.IV Congreso Nacional de Engenharia Mecânica, 2006. • João P. Monteiro, Miguel R. Silvestre, Hugh Piggott, and Jorge C. André. Wind tunnel testing of a horizontal axis wind turbine rotor and comparison with simulations from two blade element momentum codes. Journal of Wind Engineering and Industrial Aerodynamics, 123, Part A(0):99 – 106, 2013. • E. Muljadi and C.P. Butterfield. Pitch-controlled variable-speed wind turbine generation,.1999. • Fernada M. Souza, Thiago F. Oliveira, and Antonio C.P.Brasil Junior. Estudo experimental de um modelo reduzido de turbina hidrocinética. 16º POSMEC. Simpósio de Pós-Graduação em Engenharia Mecânica, 2006. • F. M. White. Mecânica dos fluidos. 6º edition, 2011. HIDRO&HYDRO: PCH NOTÍCIAS & SHP NEWS, 64 (5), JAN,MAR/2015, DA PÁG. 15-18 A FEASIBILITY STUDY ON THE USE OF WIND TUNNEL EXPERIMENTS FOR HYDROKINETIC TURBINES TECHNICAL ARTICLES ARTIGOS TÉCNICOS TECHNICAL ARTICLES INSTRUÇÕES AOS AUTORES INSTRUCTIONS FOR AUTHORS Forma e preparação de manuscrito Form and preparation of manuscripts Primeira Etapa (exigida para submissão do artigo) First Step (required for submition) O texto deverá apresentar as seguintes características: espaçamento 1,5; papel A4 (210 x 297 mm), com margens superior, inferior, esquerda e direita de 2,5 cm; fonte Times New Roman 12; e conter no máximo 16 laudas, incluindo quadros e figuras. Na primeira página deverá conter o título do trabalho, o resumo e as Palavras-chave. Os quadros e as figuras deverão ser numerados com algarismos arábicos consecutivos, indicados no texto e anexados no final do artigo. Os títulos das figuras deverão aparecer na sua parte inferior antecedidos da palavra Figura mais o seu número de ordem. 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