In a risk situation the flow through a hydropower turbine must be reduced under a short amount of time. The reduction in flow causes low pressures in the region called draft tube under the runner in the turbine. If the pressure drops below vapor pressure the water in the turbine may evaporate and form large cavities. The phenomenon called water column separation describes the situation when these cavities of vapor forms and eventually collapses which may damage the unit and canbe a danger to personnel at site. Different types of flow reducing maneuvers are tested before commissioning turbines in order to detect dangerously low pressures but these measurements can be difficult to interpret. The measured draft tube pressure can be filtered numerous ways and in addition other measured or calculated parameters must be studied to fully understand the consequence of a measured emergency stop. In this paper the different ways of filtering and interpreting the measurements from stops in Kaplan turbines were analyzed. The results show that the choice of filtering method can significantly impact the interpretation of a stop and that the filter parameters often used do not result in equivalent results. The standard way to filter draft tube pressure with moving average filters is shown to result in much higher draft tube pressures than low-pass filters and the filter parameter used needs to be further investigated to correctly isolate pressures caused by water column separation. The main difference between different companies when it comes to these measurements are the used cutoff frequency when using low-pass filters and the sampling frequency of measurements.

A dissertação trata da aplicação de técnicas de programação não linear para otimização da operação de sistemas hidroenergéticos. Foi analisado o desempenho de diferentes funções objetivo para a otimização energética, assim como de regras para deplecionamento de sistemas hidroenergéticos com configurações em paralelo e em série. Neste caso, foi utilizado um sistema hipotético de reservatórios para permitir maior adequação do sistema aos conceitos que foram testados. O sistema Paranapanema foi escolhido como caso de estudo. Para esta bacia discutem-se aspectos ligados às séries hidrológicas, que constituem o principal dado de entrada do processo de otimização. A aplicação ao sistema Paranapanema foi efetuada com otimização de períodos de até 20 anos. Foram definidas novas regras baseadas na observação dos resultados da otimização de longo período e também apresentados padrões de variação da geração e dos volumes dos reservatórios. Foram feitas comparações com a operação real observada. Apresentou-se uma aplicação à operação de tempo real, que define políticas de operação para curto prazo. Essa aplicação tem horizonte de 12 meses, partindo-se do mês atual e considerando cenários futuros baseados em prognósticos climáticos. Os resultados mostram que a partir das regras definidas é possível ter um entendimento do processo de otimização. Os padrões de variação da geração e dos volumes auxiliam na elaboração de políticas de operação. Dessa forma se tem uma visão abrangente da otimização de um sistema hidroenergético considerando os resultados da otimização dentro de um ciclo sazonal conjuntamente com as implicações da otimização de longo período. / An application analysis of nonlinear programming is developed for hydropower systems optimization. The Paranapanema system is chosen like case study and treats aspects tied to hydrological series, that constitute the main input of optimization process. Different objective functions performance are analyzed for the hydropower optimization. It analyzes rules for emptying of hydropower reservoirs with configurations in parallel and in series. In this case a hypothetical system is used to allow larger system adaptation to the concepts that are tested. An application to the Paranapanema system is made, working with periods optimization of up to 20 years. New rules are defined based on the observation of the results of long period optimization. Also variation standards of power generation and reservoirs volumes are introduced. Comparisons with the observed operation are made. An application to real time operation is made, that defines operation policies for short term. This application has horizon of 12 months, departing of the current month and considering future scenarios based on climate prediction. The results show that is possible to have an optimization process understanding from the defined rules. The generation and volumes variation standards assist in the operation policies elaboration. Thus it has a general vision of hydropower system optimization, considering the results of optimization inside seasonal cycle jointly with the optimization long period implications.

Concerns regarding the decreasing population of the American eel (reported by Castonguay et al. 1994; Haro et al. 2000) have led to design restrictions for hydropower facilities in the Eastern United States. However, the effects of these restrictions on eel passage and their impacts on power generation have not been fully researched. The goal of this study was to evaluate design parameters for bar racks that have potential to prevent entrainment of silver American eels, but also have minimal impacts on power generation. Hydraulic and biological assessments were used to determine the role of bar spacing, rack angle, and approach velocity on head loss across bar racks and the effects of bar spacing and approach velocity on eel bypass efficiency. The hydraulic assessments included computational fluid dynamics (CFD) analyses and laboratory experiments conducted in a re-circulatory flume at Alden Research Laboratory (Alden) in Holden MA. The flume allowed for determination of head losses across bar racks placed at angles of 45 and 90 degrees to the flow direction, with bar spacings of 0.75, 1.0 and 1.5 inches (19, 25 and 38 mm) and approach velocities of 1.5, 2.0 and 2.5 ft/sec (0.46, 0.61 and 0.76 m/s). Biological assessment, supported by funding from the Electric Power Research Institute (EPRI), used the same flume and included experiments with a 90 degree rack angle, bar spacings of 0.75 and 1.0 inches (19 and 25 mm), and approach velocities of 1.5 and 2.0 ft/sec (0.46 and 0.61 m/s). Bypass efficiencies, defined by the percentage of eels moving through the bypass, were evaluated for eels using three 2-hour replicate trials with nighttime releases of 30 eels per trial. Eel behavior in the vicinity of the racks was observed to the extent possible using a DIDSON acoustic camera. Experiments for the 90 degree configuration showed that the guidance efficiencies for the 0.75 inch (19 mm) spacing were greater than those for the 1.0 inch (25 mm) spacing, while the head losses for the 0.75 inch (19 mm) spacing exceeded the head losses for the 1.0 inch (25 mm) spacing by more than 10 percent. Linear regression analysis indicated that 53 percent of the variations in head width are explained by changes in the length of the eel. Results of the hydraulic evaluations were used to develop a new head loss equation that has a correlation coefficient of 98.6 percent. The results of the hydraulic and biological assessments provide a basis for quantifying the impacts of bar rack design on hydropower operation and downstream passage for American eels.

Além do discurso de desenvolvimento nacional associado à construção de usinas hidrelétricas, tem sido destacado nos planos do setor de energia, nos discursos do governo e nos documentos técnicos relativos ao processo de avaliação de impacto um potencial de indução do desenvolvimento local associado à instalação de usinas hidrelétricas no território. Este suposto desenvolvimento local é favorecido por alguns aspectos relativos à construção das hidrelétricas, como o potencial de dinamização econômica das regiões onde os projetos são instalados e o aumento das receitas dos municípios diretamente afetados, uma vez que estes passam a receber recursos financeiros provenientes diretamente da geração de energia elétrica. Neste sentido, estes fatores têm sido utilizados para justificar uma série de novos projetos, planejados e em implantação expressos nos Planos Decenais de Expansão de Energia. Devido à falta de evidências empíricas que atestem esta relação entre existência de usinas hidrelétricas no território e o desenvolvimento local, o objetivo desta tese é o de verificar se municípios diretamente afetados por hidrelétricas têm desempenho de desenvolvimento melhor do que municípios indiretamente afetados, pertencentes a uma mesma região. Neste sentido, os desempenhos de desenvolvimento de três grupos de municípios, sob influência das hidrelétricas de Machadinho, Itá, Barra Grande e Campos Novos, foram comparados a partir do teste estatístico de Mann-Whitney. Buscou-se avaliar também a correlação entre a quantidade de recursos financeiros recebidos pelos municípios diretamente afetados com o desempenho de desenvolvimento, relativo à variação de um conjunto de indicadores de desenvolvimento local no tempo. Apesar de um dos grupos ter se destacado em relação à dimensão econômica, para a maioria dos indicadores utilizados não foi possível destacar um melhor desempenho por parte dos grupos diretamente afetados. Ressalta-se que um dos grupos de municípios diretamente afetados apresentou pior desempenho em relação à produção industrial e à concentração de renda. Encontrou-se correlação positiva entre a quantidade de recursos recebidos e a produção relativa ao setor de serviços e ao IDH renda. Porém, encontrou-se uma correlação negativa para o indicador alfabetismo. Concluiu-se, para a região estudada para o período de 2000 a 2010 que as UHEs e seus fatores associados, como os recursos financeiros, não têm servido à promoção dos fatores locais de desenvolvimento. Assim, sugere-se uma discussão a partir da formação potencial de um enclave associado a esta atividade. / In addition to the national development discourse associated to the construction of hydroelectric power plants, it has been highlighted the potential of this kind of projects in promoting local development, this has been appearing in the plans for the energy sector, in the speeches of the government and in technical documents related to the environmental impact assessment process. This supposed local development is supported by some aspects concerning the construction of dams, such as the potential for economic dynamism of the regions where the projects are installed and the income increase of the directly affected municipalities, since they start to receive financial resources from the electricity generation. In this sense, these factors have been used to justify a number of new projects, planned and under construction, expressed in the Decennial Plan for Energy Expansion. Due to the lack of empirical evidence attesting this relation between existence of hydropower plants in the territory and its local development, the aim of this thesis is to determine whether municipalities directly affected by hydropower development have e better development performance than those municipalities that are indirectly affected but belong to a same region. In this sense, the development performances of three groups of municipalities, under the influence of Machadinho, Ita, Barra Grande and Campos Novos hydro powers, were compared from the statistical test of Mann-Whitney. Attempt was also made to evaluate the correlation between the amount of funds received by the municipalities directly affected and the variation of a set of indicators of local development. Although one of the groups have been highlighted in relation to the economic dimension, for most of the indicators has not been possible to highlight better performances by neither of the groups. It is noteworthy that one of the groups directly affected showed worse performance in relation to industrial production and the concentration of income. There was a positive correlation between the amount of funds received and the production concerning the service sector and the HDI income. However, it was found a negative correlation for the literacy indicator. It was concluded, to study case for the 2000-2010 periods that the HPPs and associated factors such as financial resources, have not served to the promotion of local development factors. Thus, it is suggest a debate over the potential to enclave\'s establishment due to this sort of activity.

<p>This project considers an evaluation of a potential site for a small hydropower plant located in the BioBio north irrigation system, Chile. The purpose was to analyze the potential and constraints in harnessing the energy of an existing infrastructure of irrigation canals for electrical production. The site was analyzed technically, economically and managerially. Before this project nothing was done and therefore the investigations are a main part of the project. A preliminary design for the plant was proposed and the project was named the Minicentral Quillaileo-Mininco.</p><p>Investigations showed a flow variation of 1.62-2.2 m³ per second and a gross head of 44.3 meters. Evaluation gave a possible capacity of 840 kW producing 5 800 MWh annually. Appropriate electromechanical equipment is a Francis turbine with a diameter of 0.5 meter directly coupled to a 1000 rpm synchronous generator. The penstock recommended is a DN 1200 Flowtite GRP. The station is to be fully automatic and connected to the national grid.</p><p>The revenue is based on analysis of the past three year’s electrical market. The costs are based on budget proposals, statistical values and local comparisons. The economical analysis, based on a discount rate of 12% and life span of 35 years, gives a positive cash flow within eight years and a simple payback period of 5 years. The project will have a NPV value of 444 900 USD, IRR 14.70% and B/C of 1.2. Cost per kW will be 2 980 USD. The project is recommended to be further developed.</p>

The introduction of large amounts of wind power into power systems will increase the production uncertainties due to unforeseen wind power production variations. This will have a significant impact on the required balance management quantities. The most suitable power source to balance fast production or consumption variations is hydropower because of its flexibility and low operational costs. This thesis addresses the problem of trading of electricity on the daily marketfrom a hydropower producer perspective in a system with large amounts of wind power. The overall aim is to present models that can be used in the trading decision process. This thesis describes models within three different areas:1. Modeling of the demand for balancing power by using deterministic andstochastic models. The stochastic models are based on stochastic differentialequations.2. Modeling of prices on the day-ahead and real-time markets using deterministic and stochastic models. The stochastic models are based on time series modeling.3. Short-term hydropower scheduling of trading decisions. These problems areformulated as stochastic optimization problems where the market prices arerandom variables. The first two can be used to simulate the impact of wind power on various market prices, while the third simulates how the hydropower producer responds to market prices. Thereby, the thesis presents the necessary models for short-term scheduling of hydropower for a future system with significant amounts of wind power. This thesis concludes that the proposed price models are sufficient to reflect the relevant price properties, and that the proposed short-term hydropower scheduling models can be used to simulate the actions taken by the hydropower producer in a system with significant amounts of wind power. This is also supported by the case studies in the appended publications. / QC 20100804

This project considers an evaluation of a potential site for a small hydropower plant located in the BioBio north irrigation system, Chile. The purpose was to analyze the potential and constraints in harnessing the energy of an existing infrastructure of irrigation canals for electrical production. The site was analyzed technically, economically and managerially. Before this project nothing was done and therefore the investigations are a main part of the project. A preliminary design for the plant was proposed and the project was named the Minicentral Quillaileo-Mininco. Investigations showed a flow variation of 1.62-2.2 m3 per second and a gross head of 44.3 meters. Evaluation gave a possible capacity of 840 kW producing 5 800 MWh annually. Appropriate electromechanical equipment is a Francis turbine with a diameter of 0.5 meter directly coupled to a 1000 rpm synchronous generator. The penstock recommended is a DN 1200 Flowtite GRP. The station is to be fully automatic and connected to the national grid. The revenue is based on analysis of the past three year’s electrical market. The costs are based on budget proposals, statistical values and local comparisons. The economical analysis, based on a discount rate of 12% and life span of 35 years, gives a positive cash flow within eight years and a simple payback period of 5 years. The project will have a NPV value of 444 900 USD, IRR 14.70% and B/C of 1.2. Cost per kW will be 2 980 USD. The project is recommended to be further developed.

This thesis aims to simulate and find out more about the electrical dynamics of a six-phase exciter for hydropower generators. Because ordinary electric circuit-based simulation software only simulate three-phase electrical systems, a FEM-based software is used for the electrical dynamics simulations of the six-phase system. The objective is to analyse the pulsation behaviour of the rectified electrical output on the six-phase system and compare it to the three-phase system. The three-phase system is also simulated with filters with the aim of decreasing the amplitude of the pulsations on the electrical output. It is expected that an upgraded system from a three-phase system to a six-phase system should double the pulsation frequency on the rectified electrical output. However, the result shows that the rectified electrical output of the six-phase system consists of pulsations with unexpected frequencies. The simulated RL-filter on the three-phase system shows only insignificantly small changes on the rectified electrical pulsation amplitude.

This thesis aims to simulate and find out more about the electrical dynamics of asix-phase exciter for hydropower generators. Because ordinary electric circuit-basedsimulation software only simulate three-phase electrical systems, a FEM-basedsoftware is used for the electrical dynamics simulations of the six-phase system. Theobjective is to analyse the pulsation behaviour of the rectified electrical output on thesix-phase system and compare it to the three-phase system. The three-phase systemis also simulated with filters with the aim of decreasing the amplitude of the pulsationson the electrical output.It is expected that an upgraded system from a three-phase system to a six-phasesystem should double the pulsation frequency on the rectified electrical output.However, the result shows that the rectified electrical output of the six-phase systemconsists of pulsations with unexpected frequencies. The simulated RL-filter on thethree-phase system shows only insignificantly small changes on the rectified electricalpulsation amplitude.

This report seeks to evaluate the flexibility in a number of Fortum’s hydropower stations. The deregulation of the Nordic electricity market has put an emphasis on revenue maximizing rather than cost minimizing and there are good indications that flexible assets will be even more valuable in the future when more wind power has been introduced into the system. Through interviews with people involved in the hydropower planning and operation process a number of factors with the potential of affecting the flexibility or causing deviations between planned and realized operation have been identified and explained. These interviews have also been used to identify main flexibility limitations in studied stations, and what potentially could be done to improve the flexibility. A data analysis has been performed where historical data from planned and realized operation and results from a model developed in Matlab has been studied. The developed linear programming model is used as a reference level of an idealized theoretical potential for flexibility. Volume weighted average prices have been used to measure and compare the flexibility of studied stations. The analysis shows that the studied stations can be divided into two groups with regards to their flexibility compared to the modeled flexibility. This result is somewhat confirmed by the interview findings. Factors related to constraints imposed by water rights seem to have the biggest single impact on the flexibility of hydropower stations. The potential for flexible operation varies with season and the planned and realized operation is closer to the modeled results during the winter. It is a general opinion within the organization that there is a potential for a more flexible utilization of many hydropower stations. Experience, resources, understanding in how to fully utilize the reservoirs, and how multiple stations in a river reach can be coordinated are keys to improving the flexibility.