This thesis analyses long term and short term environmental effects on geothermal power plant performance and discusses adaptive ways to improve performance. Mokai 1 geothermal power plant has been used as a case study for this investigation. Mokai 1 is a combined cycle plant where the binary cycles are air-cooled. The plant performance of an air-cooled binary cycle geothermal power plant is dependent on the environment (resource characteristics as well as weather conditions). For modelling such a power plant, two time scales are of interest: the yearly basis for aggregate plant performance for design and operations; and the daily basis for hourly plant performances for an accurate dispatch prediction. Adaptive methodology for long term performance improvement has been introduced in this work which would save money and effort in the future by keeping the provisions to adapt to changes in resource characteristics based on geothermal reservoir modelling. The investigation was carried out using a steady state computer simulator of Mokai 1 geothermal power plant. The steady sate simulator was built specifically for this work. The deviation in performance of various components is less than 5% compared to the original plant design. The model is very generic and it can be used for other plants with simple adaptation or can be used for future plant design. One of the main contributions of this work is an iterative method for modelling the environmental effect on short term performance on the air-cooled organic Rankine cycle. The ambient temperature is identified as the most influencing parameter on short term performance which influences the performance of the whole cycle in two ways. Firstly, by changing the equilibrium pressure inside the condenser, the turbine outlet pressure changes and hence, the turbine pressure ratio also changes. The turbine pressure ratio is a major parameter determining power generated by a turbine; therefore, the plant output is affected. Secondly, by changing the condenser outlet temperature with the ambient temperature, the pump inlet and outlet condition and consequently vaporizer equilibrium temperature and pressure are influenced. The developed method sought the equilibrium conditions of both condenser and vaporizer iteratively. In short, ORC cycle shifts on the T-s plane depending on the ambient temperature. This method iteratively seeks the shifted ORC on the T,s plane. Two case studies have been carried out to demonstrate the method. The developed method shows robustness and converges exponentially. The model is effective for cycles that use saturated vapour as well as superheated vapour. The model essentially assumes steady state operation of the power cycle. The possible unit time where this model can be applied is bounded by the time required by a system to come into steady state. The saturated vapour cycle yielded average error 4.20% with maximum error 9.25% and the superheated vapour cycle yielded average error 2.12% with maximum error 5.60%. The main advantage of the developed method is that it requires a minimum number of inputs: condenser (p,T), vaporizer (p,T), condenser heat load, turbine efficiency (overall), pump work and the extremum conditions of all the components. These inputs should represent typical operating conditions of a plant. The model can predict the appropriate plant performance depending on the system heat input (geothermal fluid flow in this case) and the heat sink temperature. As the method is based on basic thermodynamics rather than empirical or semi-empirical approaches, this method is widely applicable. The main focus of this work is on the ORC but the developed method is applicable to any closed Rankine cycle. In addition, application of the developed iterative method to predict plant performance based on mean yearly weather data is also discussed in the thesis. Water-augmented cooling system and optimization of plant operating point parameters have been proposed as adaptive measures to improve short term performance. Developed iterative method has been used for the short term performance analysis. The water-augmented cooling system is specifically suitable to mitigate the reduced power output during the summer. The simulated average gain in power during the summer (Jan, Feb, Nov and Dec) of an ORC of Mokai 1 geothermal power plant by incorporating a water-augmented cooling system was 2.3% and the average gain for the whole year was 1.6% based on the weather data of Taupo for the year 2005. A cost benefit analysis showed that water-augmented cooling system is more economical compared to other alternative renewable energies considered to meet summer peak demand. From the green house gas emissions perspective, water-augmented cooling is a better option than the gas fired peaking plants. Adaptive approach for short term performance improvement by optimizing operating point parameters of an air-cooled binary cycle has huge potential with possible maximum improvement in power output by about 50%. The optimization takes in to account the effects of the geothermal resource characteristics and the weather conditions. The optimization is achieved by manipulating cycle mass flow rate and vaporizer equilibrium condition. Further study on the optimizing operating points to achieve improved short term performance has been recommended for future work.

O planejamento da operação energética em sistemas hidrotérmicos de potência com um único reservatório tem como objetivo determinar a participação de usinas hidrelétricas e térmicas de forma a garantir o suprimento de energia demandada ao menor custo operacional possível, dentro de restrições físicas e técnicas do modelo. Alguns fatores tornam a solução deste problema bastante complexa destacando a não linearidade e a não separabilidade temporal aditiva. O objetivo deste trabalho é apresentar uma nova abordagem com tratamento agregado das afluências, descrevendo uma nova caracterização das distribuições de probabilidades e um novo modelo para a programação dinâmica estocástica markoviana. Nesse novo modelo da programação dinâmica estocástica markoviana, agregações plurimensais de vazões são utilizadas como entrada em um modelo de programação dinâmica estocástica markoviana modificado para discretizações temporais plurimensais. A nova abordagem proposta foi simulada em diferentes usinas hidrelétricas brasileiras localizadas em diferentes regiões geográficas e sob diferentes regimes hidrológicos. Os resultados das simulações feitas com a utilização deste novo modelo são apresentados e comparados ao modelo de programação dinâmica estocástica markoviana mensal, atualmente utilizado no setor elétrico brasileiro, com economia de custos relativas superiores a 10% em alguns casos. / The energetic operation planning on hydrothermal power systems with a single reservoir aims to determine the participation of hydroelectric power plants and thermal power plants to guaranty supply of energy demanded with the smallest possible cost, under physical and technical model boundaries. Some points became the solution of this problem complex, highlighting the non linearity and the additive non time separability. The objective of this paper is show the new approach with aggregated inflows, describing a new probability distributions featuring and a new model for the markovian stochastic dynamic programming. On this new model of markovian stochastic dynamic programming, multi monthly inflow aggregations are used as input in a model of markovian stochastic dynamic programming modified for multi months discretizations. The new approach proposed was simulated on differents Brazilian hydroelectric power plants located on different regions and under different hydrologic regime. The results of simulations using this new model are presented and compared to the model of monthly markovian dynamic programming, nowadays used on the Brazilian electrical sector, with relatives economic savings up to 10% in some cases.

O planejamento da operação energética em sistemas hidrotérmicos de potência com um único reservatório tem como objetivo determinar a participação de usinas hidrelétricas e térmicas de forma a garantir o suprimento de energia demandada ao menor custo operacional possível, dentro de restrições físicas e técnicas do modelo. Alguns fatores tornam a solução deste problema bastante complexa destacando a não linearidade e a não separabilidade temporal aditiva. O objetivo deste trabalho é apresentar uma nova abordagem com tratamento agregado das afluências, descrevendo uma nova caracterização das distribuições de probabilidades e um novo modelo para a programação dinâmica estocástica markoviana. Nesse novo modelo da programação dinâmica estocástica markoviana, agregações plurimensais de vazões são utilizadas como entrada em um modelo de programação dinâmica estocástica markoviana modificado para discretizações temporais plurimensais. A nova abordagem proposta foi simulada em diferentes usinas hidrelétricas brasileiras localizadas em diferentes regiões geográficas e sob diferentes regimes hidrológicos. Os resultados das simulações feitas com a utilização deste novo modelo são apresentados e comparados ao modelo de programação dinâmica estocástica markoviana mensal, atualmente utilizado no setor elétrico brasileiro, com economia de custos relativas superiores a 10% em alguns casos. / The energetic operation planning on hydrothermal power systems with a single reservoir aims to determine the participation of hydroelectric power plants and thermal power plants to guaranty supply of energy demanded with the smallest possible cost, under physical and technical model boundaries. Some points became the solution of this problem complex, highlighting the non linearity and the additive non time separability. The objective of this paper is show the new approach with aggregated inflows, describing a new probability distributions featuring and a new model for the markovian stochastic dynamic programming. On this new model of markovian stochastic dynamic programming, multi monthly inflow aggregations are used as input in a model of markovian stochastic dynamic programming modified for multi months discretizations. The new approach proposed was simulated on differents Brazilian hydroelectric power plants located on different regions and under different hydrologic regime. The results of simulations using this new model are presented and compared to the model of monthly markovian dynamic programming, nowadays used on the Brazilian electrical sector, with relatives economic savings up to 10% in some cases.

Thesis (M. Phil.)--University of Hong Kong, 1996. / Includes bibliographical references (leaf 245-252).

Abstract This Bachelor thesis has been written at the Blekinge Institute of Technology. The thesis describes electricity production in Shoaiba Steam Power plant in Saudi Arabia. Shoaiba Power Plant is located 100 km South of Jeddah city in Saudi Arabia. Total power production ability reaches 4400 MW. Shoaiba Power Plant has two stages and is constructed with 11 units, each unit produces 400 MW at line voltage 24 kV and line current 16 kA. Main pieces of equipment and their function in the station are as follows: A Steam Generator (boiler), produces steam by burning natural gas or crude oil in the furnace. The steam is superheated and is passed into a steam turbine, which converts the thermal energy of the steam into mechanical power, in form of rotary motion. The turbine drives a generator, which converts the rotary energy of the turbine into electric power. Steam generator, steam turbine and electrical generator are components that are described in the thesis. When the flow of steam to the turbine is controlled, then the amount of thermal energy that changes to mechanical energy in the steam turbine is controlled. The electrical generator is where the final energy conversion takes place. The mechanical energy from the turbine is converted by the generator into electrical energy, which is transmitted to the service area by help of electrical transmission lines. The plant cycle is an essential part of the energy flow path. Without the plant cycle, the conversion of thermal energy into mechanical energy would not occur, The plant cycle is a closed loop that allows the same water to be used over and over again. Always, the power plants are situated far from residential areas and located outside cities and close to the sea, because the steam is produced from seawater. The advantages of the steam power stations are as follows: They can produce high amounts of electrical energy from small amounts of fuel. They have low initial costs, obstetrics and maintenance costs are not high, and the stations do not need much space to be built and they have usually high capacity. The disadvantages of steam stations are the following: They cause environmental pollution, they have low efficiency, and require very big quantities of cooling water, and the stations must be built away from populated areas. / Conclusion: Converting in steam power plant is one of many ways to produce electrical energy in the world. It can be done in any country because it can be done with different chemical sources. In Saudi Arabia we use oil, because it easier and cheaper than any other chemical source for us. As any country would use what is better for them. The thesis has described circulation system in Shoaiba power plant by converting chemical energy to thermal energy in the boiler, then the turbine converts thermal energy to mechanical energy. Then the mechanical energy is converted to electrical energy in the generator. The advantages of the steam stations are as follows: production of high amounts of electrical energy from small amounts of fuel, low cost of the initial costs, obstetrics and maintenance costs are not high, the station does not need much space to build and they are usually high capacity. The disadvantages of steam stations are the following: environmental pollution, low efficiency, requires very big amounts of cooling water, and these stations must be built away from population areas. / 0706397524

This thesis proposes a method and develops a model for the participation of a combined cycle power plant to power system frequency control. Through the period of integration to the UCTE system, (Union for Coordination of Transmission of Electricity in Europe) frequency behavior of Turkey&rsquo / s grid and studies related to its improvement had been a great concern, so is the reason that main subject of my thesis became as &ldquo / Power System Frequency Control&rdquo / . Apart from system-wide global control action (secondary control) / load control loops at power plants, reserve power and its provision even at the minimum capacity generation stage, (primary control) are the fundamental concerns of this subject. The adjustment of proper amount of reserve at the power plants, and correct system response to any kind of disturbance, in the overall, are measured by the quality of the frequency behaviour of the system. A simulator that will simulate a dynamic gas turbine and its control system model, together with a combined cycle power plant load controller is the outcome of this thesis.

Orientadores: Paulo de Barros Correia, Ieda Geriberto Hidalgo / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-28T12:05:23Z (GMT). No. of bitstreams: 1 Barros_RegianeSilvade_D.pdf: 4190585 bytes, checksum: c320645bbd13fd28d572f5b9751d4ff7 (MD5) Previous issue date: 2015 / Resumo: Este trabalho propõe um modelo de despacho ótimo no horizonte diário de operação, que permite coordenar a operação entre uma usina eólica e uma usina hidrelétrica. Nessa abordagem, a usina eólica é despachada em primeira instância. Para suprir eventuais saídas forçadas que possam ocorrer na geração eólica, aloca-se um valor de reserva girante incremental na usina hidrelétrica usando o conceito de Value at Risk como métrica de risco da geração eólica. O modelo é formulado como um problema multiobjetivo que busca maximizar a geração de energia e minimizar o número de partidas e paradas da usina hidrelétrica. O acoplamento hidráulico é considerado através da meta diária de defluência da usina. O problema é solucionado em duas etapas. A primeira resolve 24 problemas estáticos, que representam o despacho horário da usina hidrelétrica, separadamente. Essa etapa emprega o Algoritmo Genético para otimizar a operação da usina em termos da geração de energia elétrica. A segunda etapa soluciona o problema dinâmico, ou seja, o despacho diário da usina. A natureza do problema dinâmico, correspondendo à obtenção de caminhos mínimos eficientes em termos de partidas e paradas, sugeriu o uso da técnica de Otimização por Colônia de Formigas. As restrições de reserva girante, meta de defluência, atendimento do contrato de demanda e limites operacionais das usinas são plenamente satisfeitas. A diferença entre os montantes de energia produzidos e contratados é liquidada no mercado de curto prazo e valorada ao preço de liquidação das diferenças. O modelo se mostrou adequado em termos de tempo computacional e em relação à qualidade das soluções obtidas / Abstract: This work proposes an optimal dispatch model in the daily horizon, which coordinates the operation of a wind farm and a hydroelectric plant. In this approach the wind farm is dispatched first. In order to provide eventual faults that may occur in the wind farm generation, an incremental spinning reserve is allocated in the hydroelectric plant using the concept of Value at Risk. The model is formulated as a multiobjective problem which seeks to maximize the energy generation and to minimize the number of start-ups and shut-downs of the hydroelectric plant. The plant¿s hydraulic coupling is considered through the daily released flow goal. The model is solved in two stages, the first one solves, separately, 24 static problems that represents the hourly dispatch of the hydroelectric plant. This stage employs Genetic Algorithm to optimize the operation of the hydroelectric plant in terms of electric energy generation. The second stage considers the dynamic problem, which is the plant¿s daily dispatch. The nature of the dynamic problem, which implies in obtaining efficient shortest paths in terms of start-ups and shut-downs, suggests the use of the Ant Colony Optimization. The spinning reserve, the released flow goal, the demand contract and the generating unit¿s operational limits are fully satisfied. The difference between the energy amounts produced and contracted are liquidated in the spot market and it is valuated with the settlement differences price. Regarding computational costs and solutions quality, the model suitability is shown / Doutorado / Planejamento de Sistemas Energeticos / Doutora em Planejamento de Sistemas Energéticos

This diploma thesis is divided into two parts, namely the theoretical and practical part. In the theoretical part, the issue is dismantled from the current state of electric power, share the production of individual sources, the market for photovoltaic and mobile photovoltaic systems through the description of the theory of solar radiation and all the necessary components to build the isolated photovoltaic power plant. The practical part deals with dimensioning, selection of suitable components and the actual one own design and implementation of a mobile photovoltaic power plant.

This thesis deals with operation of the Jasenie hydroelectric power plant, which supplies electricity to Železiarne Podbrezová Inc. This thesis describes actual operation, devices and equipment in all substations. The second chapter briefly describes company’s history and activities of the company. The next chapter mentions an overview of the sources of own electricity production. The fourth chapter in detail deals with actual situation of the hydroelectric power plant operation, describes devices and equipment in all substations. It also outlines what measures should be taken to increase the reliability of electricity supply. Next part deals with replacing insulators on the 22 kV line. Sixth chapter is focused on protection this line by multifunctional protection relay and data transfer from HC Jasenie to the building of power engineering. In the next step is designed a backup transformer with bus control for thermal and dynamic effects of the short-circuit current. The last chapter is focused on surge protection in HC Jasenie as well as in the area of Stary závod substation. The results and benefits of this work are summarized in the conclusion. The attachment contains schemes of substations and overall overview scheme, which are used for better understanding of this problem.

This thesis concerns with design of micro sources and their implementation in Micro grid system. In the first part the work is aimed at definition of smart - grid, where describes their advantages, disadvantages and necessary changes, which has to be made in current distribution network for implementation this system. Further on the thesis concerns with detailed description of Micro grid, configuration of this kind of network, the issues in implementation and possibilities to provide ancillary services. The work also describes marginally virtual power plants, presents definition, components and types of virtual power plants. The final chapter describes the creation of micro sources in System modeler and subsequent testing of consumption cover to operate in island mode.