In this study, Lithium iron oxide (LiFeO₂ – LFO) was investigated as a new anode material for the high temperature SOFCs. From the DC conductivity measurement in argon containing 5% H₂, LFO exhibits good electronic conductivity of 5.08 Scm⁻¹ at 650 °C. LFO poses a high TEC value of 19.5 x 10⁻⁶ K⁻¹ in air. However, the TEC values of the commonly used 8YSZ and CGO electrolytes are much lower, 10.5 x 10⁻⁶ K⁻¹ and 12.5 x 10⁻⁶ K⁻¹ respectively. In order to resolve the mismatch in the TEC values between the electrode and the electrolyte, button fuel cells were fabricated via tape casting. LFO was infiltrated onto the porous and stable scaffold. Presently, the predominant electrolyte material used for the high temperature SOFC is 8YSZ. Due to this reason, the initial performance of LFO as an anode material was tested on tape-cast 8YSZ electrolyte-supported cell. The 8YSZ electrolyte-supported infiltrated with 30 wt% LFO for the anode and 40 wt% LSF for the cathode achieved a maximum power density of 50 mWcm⁻² at 700 °C in humidified H₂. Increasing the weight loading of LFO to 40 wt% worsen the performance. XRD pattern of the sintered powder containing 50 wt% LFO and 50 wt% 8YSZ confirmed that LFO and 8YSZ react with each other. CGO was considered as an alternative electrolyte material to 8YSZ. XRD pattern of the sintered powder containing 50 wt% LFO and 50 wt% CGO confirmed that they are compatible with each other. The CGO electrolyte supported cell infiltrated with 40 wt% LFO for the anode and 40 wt% LSC for the cathode achieved a maximum power density of 180 mWcm⁻² at 650 °C in humidified H₂. The addition of 10 wt% ceria to the LFO anode enhances the electrochemical activities of the cell. However, the overall performance of the cell decreased due to a larger increase in the series resistance. Since CGO electrolyte is easily reduced when testing at temperature higher than 550 °C, LSGM was used to increase the testing temperature. The 245 µm thick LSGM electrolyte-supported cell infiltrated with 40 wt% LSC and 30 wt% LFO obtained a maximum power density of 227 mWcm⁻² at 700 °C in humidified H₂. Decreasing the electrolyte thickness from 245 µm to 130 µm increased the performance of the cell. The 130 µm LSGM electrolyte-supported cell infiltrated with 40 wt% LSC and 30 wt% LFO was tested with the carbon/carbonate fuel as a HDCFC. Performance measurements of the cell was conducted at 650 °C and 700 °C with N₂ flowing at 20 ml/min. The cell performed better when testing at higher temperature. Recently, there has been great interest in developing a SOFC system for the cogeneration of electricity and valuable C₂ chemicals. The catalytic testing for oxidative methane coupling of methane revealed a high C₂ selectivity for the LFO powder. Cell testing of a sample infiltrated with 40 wt% LSC and 30 wt% LFO also achieved a methane conversion of ~3% and a C₂ selectivity of ~80% in methane at 700 °C.

Resumo Partindo da constatação das péssimas condições de vida da maioria do povo brasileiro 34,1% vivendo abaixo da linha da pobreza e da crescente lucratividade da indústria de energia elétrica no país, o presente trabalho procurou uma forma dessa indústria contribuir para saldar parte do passivo social brasileiro. Os resultados obtidos pelos estudantes brasileiros, em praticamente todos os processos de avaliação existentes, indicam que o baixo nível do ensino público é um dos maiores problemas que o país tem a enfrentar no curto prazo. As projeções da evolução da pirâmide etária da população brasileira indica que, em poucos anos, a maioria da população já se encontrará em idade ativa, ou seja, já deverá ter sua formação escolar concluída, o que indica a urgência da busca pela melhoria da qualidade do ensino fundamental. As externalidades dos investimentos públicos em educação, sendo superiores aos retornos privados, justificam a atuação do Estado nessa atividade de relevância inquestionável para a construção da nação.Demonstrada a forte correlação entre o desempenho dos estudantes do ensino fundamental e a produção per capita dos países, é feita uma proposta de utilização de recursos gerados na indústria de energia elétrica brasileira para aplicação em ações que busquem mais qualidade no ensino fundamental do país. A proposta, que não eleva os custos da indústria e não significa elevação de tarifa para o usuário final, é a prorrogação por 5 anos do recolhimento da RGR (Reserva Global de Reversão), cuja extinção está prevista para o final de 2010. O valor recolhido anualmente permitiria quase dobrar os valores aplicados na ação de melhoria da qualidade do ensino no orçamento federal de 2009, devendo antecipar as metas de desempenho propostas no Plano de Desenvolvimento da Educação PDE, que busca alcançar os níveis obtidos pelos países da OCDE em 2025. Outros trabalhos podem ser desenvolvidos, buscando alternativas de financiamento da educação no Brasil, considerando a renda do petróleo que poderá ser obtida a partir da exploração do óleo do pré-sal. / Abstract Starting from the observation of the awful living situation of the majority of the Brazilian population 34.1% living below the poverty line and the increasing profitability of the electricity industry in the country, this project aimed at finding a way in which the electricity industry could provide financial assistance to eliminate part of the Brazilian social passive. The results obtained by Brazilian students - in practically all the available evaluation processes indicate that the poor level of publicly funded education is one of the most important problems that Brazil has to face in the short term. The projections of evolution on the age pyramid indicate that in a few years most of the Brazilian population will be in the active age group. In other words, the majority of the population should have concluded their formative education. This projection indicates the urgent need of improving the quality of basic (fundamental) education. The externalities of the public investment in education, being larger than the private return, justify the argument for government intervention, since education is without a doubt of extreme relevance for the nation development. Since the correlation between the basic level students performance and the countries per capita production has been demonstrated, we propose the use of resources generated by the Brazilian electricity industry on funding programs to improve the quality of basic level education in the country. Its proposed that, and it does not imply increased costs to the industry or increase in the final cost to the consumer, that the Global Reserve of Reversion (GRR ) collection should be extended for 5 additional years. The GRR collection was programmed to stop in the end of 2010. This annual contribution would allow almost double the amount that is applied towards programs to improve the quality of basic level education as established by the federal budget in 2009, therefore anticipating the goals set by the Education Development Plan (EDP). The EDP aims to reach the same levels attained by the countries members of the Organization for Economic Cooperation and Development (OECD) in 2025. Other similar projects could be developed to find alternative sources of funding for education in Brazil. One such source to be considered in the future is the profit that may be obtained by the oil production in the new pré-sal area. 1. Translated from Reserva Global de Reversão (RGR) Compulsory contribution created by the Brazilian government for electricity sector companies. The money is used for improvements in that sector. 2. Plano de Desenvolvimento da Educação (PDE) A government plan to improve the Brazilian public education level.

O setor elétrico é um setor de natureza estratégica para qualquer nação, na medida em que na era moderna a eletricidade é um insumo fundamental para a qualidade de vida das pessoas e para o desenvolvimento e a produção da indústria, sendo mesmo considerado como uma mola mestra da economia do país. Em função dessa importância, crescente ao longo do tempo e aguçada em decorrência de restrições de disponibilidade e de cunho ambiental para a utilização massiva do petróleo, o setor elétrico deve ser planejado com extrema atenção e de forma muito criteriosa, posto que sua expansão necessite estar garantida e se trata de um setor intensivo em capital e com empreendimentos de longo prazo de maturação, particularmente no caso dos grandes aproveitamentos hidrelétricos e as plantas nucleares. Dentro desse contexto, o presente trabalho buscou endereçar a temática de planejamento de sistemas elétricos, aproveitando a experiência profissional pregressa da autora, especialmente no que tange às vertentes de estudos tarifários e de mercado, como também pelo fato de conhecer em algum detalhe os marcos regulatórios e o funcionamento dos setores elétricos no âmbito do Mercosul. Nesse sentido, o presente trabalho apresenta uma análise crítica comparativa de modelos tarifários, dos sistemas de transmissão, atualmente vigentes em alguns países da América do Sul. As recentes tendências políticas e energéticas dos países considerados constituem-se em importantes sinais para o estabelecimento de futuras negociações na área elétrica. Isso propicia a realização de um estudo referente às condições tarifarias e regulatórias destes mercados. Questões técnicas em projetos deste tipo poderiam ser superadas, porém, eventuais divergências regulatórias e tarifarias entre os mercados elétricos poderiam adiar ou até mesmo inviabilizar os referidos projetos. Por outro lado, levando em conta o nexo existente entre o estudo dos modelos tarifários, os sinais de possíveis negociações de energia e a expansão do sistema, apresentam-se também uma análise comparativa entre as metodologias de previsão utilizadas no cálculo da demanda de energia elétrica nos países considerados. As referidas metodologias de previsão, sobre as quais foram utilizados o histórico de consumo do Brasil (1996-2006) e as variáveis explicativas inerentes a cada modelo, correspondem às classes de consumo Residencial, Industrial, Comercial e Rural; responsáveis por aproximadamente 90% do consumo nacional. Foram encontradas certas semelhanças principalmente no relacionado às variáveis econométricas utilizadas por estes modelos, os quais se refletiram nos resultados obtidos. / The electric power sector is an area of strategic nature for any country as electricity is an essential product for both the quality of life and the development of the industry. This reason led to consider it as a sound foundation for the economy development and GNP growing. Because of its role, which grows along time even due to the restrictions of availability and environmental issues for the massive use of oil, the electric sector must be carefully planned as its expansion needs to be guaranteed. This sector embraces large capital and long-term investments, particularly those related to hydroelectric projects and nuclear plants. Within that framework, this work aims at to address the electric power planning subject using the author\'s past knowledge related to electric tariffs as well as on the regulatory framework and market operation of the Mercosul. A critical comparative analysis of transmission tariff models currently applied in some South American countries is particularly addressed. The recent political and energy policy trends of the considered countries appear as important signals for the establishment of future negotiations of electricity. This situation demands the realization of new studies related to both tariff and regulatory conditions in these markets. Technical issues in projects of this kind may well be overcome; however, some regulatory differences and even tariff model differences among marketers could delay or even turn unfeasible the referred projects. On the other hand, considering issues like the link existing among the transmission pricing models adopted and the likely electricity trading as well as the system expansion, a comparative analysis of the methodologies used to forecast the energy demand in the South American countries previously considered, is also presented. Such forecast methodologies, upon which were applied the annual electricity consumption in Brazil in the period 1996 through 2006 as well as the explanatory variables inherent to each model, correspond to the Residential, Industrial, Commercial and Rural consumptions, responsible for nearly 90% of the national consumption. From this analysis, some similarities mainly those related to the econometric variables used by each methodology were found. Such similarities and related findings are reflected in the results presented.

Resumo Partindo da constatação das péssimas condições de vida da maioria do povo brasileiro 34,1% vivendo abaixo da linha da pobreza e da crescente lucratividade da indústria de energia elétrica no país, o presente trabalho procurou uma forma dessa indústria contribuir para saldar parte do passivo social brasileiro. Os resultados obtidos pelos estudantes brasileiros, em praticamente todos os processos de avaliação existentes, indicam que o baixo nível do ensino público é um dos maiores problemas que o país tem a enfrentar no curto prazo. As projeções da evolução da pirâmide etária da população brasileira indica que, em poucos anos, a maioria da população já se encontrará em idade ativa, ou seja, já deverá ter sua formação escolar concluída, o que indica a urgência da busca pela melhoria da qualidade do ensino fundamental. As externalidades dos investimentos públicos em educação, sendo superiores aos retornos privados, justificam a atuação do Estado nessa atividade de relevância inquestionável para a construção da nação.Demonstrada a forte correlação entre o desempenho dos estudantes do ensino fundamental e a produção per capita dos países, é feita uma proposta de utilização de recursos gerados na indústria de energia elétrica brasileira para aplicação em ações que busquem mais qualidade no ensino fundamental do país. A proposta, que não eleva os custos da indústria e não significa elevação de tarifa para o usuário final, é a prorrogação por 5 anos do recolhimento da RGR (Reserva Global de Reversão), cuja extinção está prevista para o final de 2010. O valor recolhido anualmente permitiria quase dobrar os valores aplicados na ação de melhoria da qualidade do ensino no orçamento federal de 2009, devendo antecipar as metas de desempenho propostas no Plano de Desenvolvimento da Educação PDE, que busca alcançar os níveis obtidos pelos países da OCDE em 2025. Outros trabalhos podem ser desenvolvidos, buscando alternativas de financiamento da educação no Brasil, considerando a renda do petróleo que poderá ser obtida a partir da exploração do óleo do pré-sal. / Abstract Starting from the observation of the awful living situation of the majority of the Brazilian population 34.1% living below the poverty line and the increasing profitability of the electricity industry in the country, this project aimed at finding a way in which the electricity industry could provide financial assistance to eliminate part of the Brazilian social passive. The results obtained by Brazilian students - in practically all the available evaluation processes indicate that the poor level of publicly funded education is one of the most important problems that Brazil has to face in the short term. The projections of evolution on the age pyramid indicate that in a few years most of the Brazilian population will be in the active age group. In other words, the majority of the population should have concluded their formative education. This projection indicates the urgent need of improving the quality of basic (fundamental) education. The externalities of the public investment in education, being larger than the private return, justify the argument for government intervention, since education is without a doubt of extreme relevance for the nation development. Since the correlation between the basic level students performance and the countries per capita production has been demonstrated, we propose the use of resources generated by the Brazilian electricity industry on funding programs to improve the quality of basic level education in the country. Its proposed that, and it does not imply increased costs to the industry or increase in the final cost to the consumer, that the Global Reserve of Reversion (GRR ) collection should be extended for 5 additional years. The GRR collection was programmed to stop in the end of 2010. This annual contribution would allow almost double the amount that is applied towards programs to improve the quality of basic level education as established by the federal budget in 2009, therefore anticipating the goals set by the Education Development Plan (EDP). The EDP aims to reach the same levels attained by the countries members of the Organization for Economic Cooperation and Development (OECD) in 2025. Other similar projects could be developed to find alternative sources of funding for education in Brazil. One such source to be considered in the future is the profit that may be obtained by the oil production in the new pré-sal area. 1. Translated from Reserva Global de Reversão (RGR) Compulsory contribution created by the Brazilian government for electricity sector companies. The money is used for improvements in that sector. 2. Plano de Desenvolvimento da Educação (PDE) A government plan to improve the Brazilian public education level.

Orientador: Antonio Padilha Feltrin / Banca: Rubén Augusto Romero Lázaro / Banca: Jose Roberto Sanches Mantovani / Banca: Edgar Manuel Carreño Franco / Banca: Carlos Alberto Castro Júnior / Resumo: Dentre as profundas mudanças que os sistemas de distribuição de energia elétrica vêm experimentando nas últimas décadas, a crescente penetração da Geração Distribuída (GD) representa ainda uma série de desafios técnicos para as redes de distribuição tradicionalmente concebidas. Essa tendência na alteração do paradigma de concepção, planejamento e operação das redes de distribuição de energia elétrica tem suscitado a necessidade de inovação nas metodologias e ferramentas computacionais de análise. Assim, este trabalho procura investigar as potencialidades das meta-heurísticas de otimização multiobjetivo (OM) como ferramenta para a análise de impacto da penetração da GD nas redes de distribuição de média tensão. Esse esforço pode ser dividido em duas etapas: a primeira concentrada sobre as técnicas de solução de modelos de OM e a segunda dirigida para o estudo do impacto causado pela GD em aspectos técnicos da rede de distribuição, como nível de tensão, curto-circuito e capacidade, considerando-se o problema de planejamento da expansão das redes de distribuição. Quanto ao estudo das técnicas de OM, fez-se um conjunto de investigações sobre os conceitos de otimização multiobjetivo, os principais métodos baseados em meta-heurísticas e na aplicação de OM a problemas de sistemas de potência, especialmente os relacionados à inserção da GD nas redes de distribuição. Foram implementados os métodos Nondominated Sorting Genetic Algorithm II (NSGA-II), baseado em Algoritmos Genéticos, e Busca Tabu multiobjetivo (BTMO). Finalmente, desenvolveu-se no âmbito desta tese o algoritmo Multi- objective Evolutionary Particle Swarm Optimization (MEPSO) com o objetivo de explorar os ganhos de desempenho verificados com a meta-heurística híbrida... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The Distributed Generation (DG) plays an important role in the profound changes that distribution power systems are facing in the last decades. The impacts caused by high DG penetration are still a challenge for traditional distribution networks. Then, there is a need for innovation and development of computational tools for system analysis considering the new trends for designing, planning and operating distribution networks. This work investigates the potential of meta-heuristics for multi-objective optimization (MO) to evaluate the impact of the penetration of DG in medium voltage distribution networks. The research may be divided in two parts: firstly, the study is focused on the techniques for solving MO problems and the second part aimed to evaluate the impact of DG on technical aspects of the distribution network, such as voltage levels, short-circuit and current capacity, considering the problem of expansion planning of the distribution network. Regarding the study of the techniques of MO, the concepts of multi-objective optimization was investigated as well as the main meta- heuristic based methods and the application of the MO to power systems problems, especially those related to the integration of DG in distribution. Two methods were implemented: the Nondominated Sorting Genetic Algorithm II (NSGA-II), based on Genetic Algorithms and a multi-objective Tabu Search (MOTS). Finally, the algorithm of a Multi-objective Evolutionary Particle Swarm Optimization (MEPSO) was developed within this thesis in order to exploit the performance gains observed with the hybrid meta-heuristic Evolutionary Particle Swarm Optimization (EPSO) in single-objective optimization problems. Concerning the study of the impact of DG, a methodology for analysis of the Pareto front was proposed which allows, in addition to obtaining... (Complete abstract click electronic access below) / Doutor

<p>The theme of this thesis is the supply of capacity during peak demand in restructured power systems. There are a number of reasons why there is uncertainty about whether an enegyonly electricity market (where generators are only paid for the energy produced) is able to ensure uninterrupted supply during peak load conditions.</p><p>Much of the public debate in Europe has been about the present surplus generation capacity. However, in a truly competitive environment, it is hard to believe that seldom used capacity will be kept operational. This is illustrated by developments in Sweden. For this reason, the large surplus of generation capacity in the European Union may vanish much faster than generally assumed. In the USA, much of the debate has been about California. During the last three summers, California has occasionally experienced involuntary load shedding and prices have been very high during these periods. To some extent, the Californian situation illustrates the relevance of the subject of this thesis: in a deregulated system generators may not be willing to invest in peaking capacity that is only needed occasionally, even though prices are very high during these periods.</p><p>A good solution to the problem of providing peaking power is pivotal to the success of power market restructuring. Solutions that fail to create the right incentives will result in unacceptable load shedding and can endanger the whole restructuring process. On the other hand, solutions that pay too much for investments in peaking power will lead to generation capacity surpluses and thus represent a societal loss.</p><p>Why is peaking capacity a problematic issue in energy-only markets?</p><p>Traditionally, probabilistic methods are applied to calculate the required generation capacity to obtain a desired level of reliability. In a centrally planned system, this level of generation capacity is developed in a least-cost manner. A single utility or central authorities can thus control the level of reliability directly. This is not possible in a market-based system, if suppliers are only paid for the energy produced.</p><p>Under the assumption of certainty and continually varying prices, generators fully recover their variable and investment costs under ideal market conditions. When uncertainty is taken into account, generators will cover their expected costs. However, revenues will be extremely volatile, especially for peaking generators. Combined with a risk-averse attitude, it is unlikely that investments will be sufficient to maintain the traditional level of reliability in an energyonly market. Consequently, one would expect reserve margins to decline in such markets. This effect is very clear in Sweden that deregulated in 1996, and less explicit in a number of other cases like Norway, California and Alberta.</p><p>Pricing and Consumer Preferences</p><p>The theory of electricity pricing was originally developed for vertically integrated utilities, but elements from this theory are also valuable in a restructured context. Many authors have agreed on the presence of a capacity element in the optimal price during peak-load conditions, while price should equal marginal cost during low-load conditions. An important assumption is that prices have to be stable. More recently, spot pricing of electricity has been advocated. A number of papers have been written about how to efficiently include security considerations in the spot price.</p><p>Because the availability of capacity cannot be directly controlled in an energy-only spot market, the probability of occasional capacity shortages increases. It is important to be prepared for this situation. The core of the problem is that demand is de facto inelastic in the short-term because of traditional tariff systems. It is shown that considerable economic gains are obtained when demand elasticity can be utilized, even if only minor shares of demand are elastic in the short-term. Better utilization of demand elasticity was also profitable in traditional systems, but after restructuring the gain is much larger: the alternative is not expensive generation but random rationing, which is unacceptable in modern society.</p><p>It is possible to go one step further. Consumers have different preferences for the use of energy and reliability. Some consumers have a low tolerance about being disconnected, while others are more willing to accept this. This will be reflected by their willingness to pay for reliability. A better solution would emerge if consumers could buy electricity and reliability more or less as separate commodities, based on their preferences.</p><p>In the context of pricing it should be pointed out that ”profile-based settlement” that allows small consumers to freely choose their supplier without hourly metering is detrimental with respect to the correct pricing of capacity. It should only be used in the initial phases of opening a market.</p><p>Improved utilization of system resources</p><p>Even in the short-term, demand and the availability of generation and transmission resources are uncertain. Therefore, it is necessary to have reserves available in a power system. When capacity becomes scarce, it is difficult to satisfy the reserve requirements. If these requirements are strict, the only possibility is to resort to what can be called ”preventive loadshedding” to satisfy the reserve requirements. This is obviously an expensive solution, but there are no obvious ways of balancing the (societal) cost of preventive load shedding against reduced system security. In this thesis, a model is developed for unit commitment and dispatch with a one-hour time horizon, with the objective of minimizing the sum of the operation and disruption costs, including the expected cost of system collapse. The model is run for the IEEE Reliability Test System. It is shown that under conditions where there is not enough capacity available to satisfy the reserve requirements, large cost savings can be obtained by optimizing the sum of the operation and disruption costs instead of using preventive load-shedding. In the model, it is also possible to directly target reliability indexes like the Loss of Load Probability or Expected Energy not Served. It is shown that increased reliability (in terms of the values of the indexes) can be obtained at a lower cost by targeting the indexes directly instead of resorting to reserve requirements. This is especially the case if flexible load-shedding routines are developed, making it possible to disconnect and reconnect the optimal amounts of load efficiently.</p><p>The use of alternatives to fixed reserve requirements as a means to maintain system security does not solve the problem about how to ensure the availability of peaking capacity. However, in a situation with occasional capacity shortages, it gives the System Operator a tool to find the optimal balance between preventive load shedding and system security, which can result in significantly lower disruption costs in such cases. More research and development in this area is necessary to develop methods and tools that are suitable for large power systems.</p><p>Ancillary Services</p><p>Investment in peaking capacity is insufficient in restructured systems because expected revenues are too low or too uncertain. If generator revenues are increased, the situation improves. One way to obtain this is to create markets for ancillary services. In the thesis, a model is developed for a central-dispatch type of pool. In this model, markets for energy and three types of ancillary services are cleared simultaneously for 24 hours ahead. Market prices are such that volumes and prices are consistent with the market participants. self-dispatch decisions . i.e. given these prices, market participants would have chosen the same production of energy and ancillary services as the outcome of the optimization program. With this model, it is shown that markets for ancillary services increase generator revenues, but this effect is partly offset by lower energy prices. This shows that markets for ancillary services can contribute to improving the situation, but given the remaining uncertainty, this is hardly enough to solve the problem.</p><p>Capacity Subscription</p><p>Because consumers have preferences for two goods: electricity and reliability, they should ideally have the choice of purchasing the preferred amount of each of these. Traditionally this is not possible . reliability is a public good, produced or obtained by a central authority on behalf of all consumers. Technological progress is presently changing this. Capacity subscription is a method that allows consumers to choose their individual level of reliability, at the same time creating a true market for capacity. It is based on the concept of selfrationing. Consumers anticipate (for example on a seasonal basis) their need for capacity at the instant of system-wide peak demand. Based on this anticipation, they procure their desired level of capacity in a market, where generators offer their available capacity. Demand is limited to subscribed capacity by a fuse-like device that is activated when total demand exceeds total available generation. In this way, the capacity payment only influences the market when demand is close to installed capacity, and does not distort the energy price in other periods. Demand is not limited when there is ample capacity. Demand will never exceed supply, because it can be limited in an acceptable way when this situation occurs. Moreover, both consumers and suppliers can adapt to situations with scarce or ample capacity, and the price of capacity will reflect this situation. There is one problem with the method: as consumers do not reach their subscribed capacity simultaneously, there will be a capacity surplus at the instant the fuse-devices are activated. Two methods to solve this problem are analysed, and it is shown that the problem can be solved optimally by giving consumers who prefer this the opportunity to buy power in excess of their subscription on the spot market.</p><p>Policy evaluation</p><p>Six alternative policies to assess the peaking power problem are analysed based on the following criteria:</p><p>- Static efficiency: the welfare-optimal match of consumption and supply</p><p>- Dynamic efficiency: the ability to create incentives for innovation</p><p>- Invisibility: with invisible strategies, each market actor pursues his or her own objectives without worrying about anyone else.s</p><p>- Robustness: a robust policy is less sensitive to deviations from assumptions</p><p>- Timeliness: the ability of a policy to be employed at the right time</p><p>- Stakeholder equity: the degree to which all the involved parties are treated equitable</p><p>- Corrigibility: the extent to which a policy can be corrected once it is employed</p><p>- Acceptability: the degree to which the policy is acceptable to all parties</p><p>- Simplicity: ceteris paribus simple strategies are preferable over more complicated strategies</p><p>- Cost: the cost of implementing the policy</p><p>- System security: the policy.s ability to obtain an acceptable level of system security</p><p>The policies are, in short (an example is given in parentheses):</p><p>- Capacity obligation: suppliers are obliged to keep sufficient capacity (PJM)</p><p>- Fixed capacity payment: a fixed payment is offered for available capacity (Spain)</p><p>- Dynamic capacity payment: capacity payment is based on the Loss of Load Probability (England and Wales)</p><p>- Energy-only: no explicit payments or obligation (Scandinavia, California)</p><p>- Proxy prices: very high administrative prices are used as a proxy to the Value of Lost Load when load shedding is necessary (Australia)</p><p>- Capacity subscription: cf. the description above (not implemented)</p><p>As could be expected, no single policy performs best on all criteria. The obligation and fixed payment methods do not perform well on market efficiency criteria, as essentially they are not market-based policies. The proxy prices policy is a reasonable policy on most criteria. It is easy, cheap and quick to implement. Because there is little experience with the method so far, there is some uncertainty with respect to if it is effective. One can anticipate that the threat of having to buy power at rationing prices will motivate market participants to avoid coming in a buying position in such cases, and that this will stimulate the adaptation of innovative solutions, especially on the demand side.</p><p>The capacity subscription policy looks very promising on the issues of efficiency, robustness and system security. This is especially true for dynamic efficiency: consumers will weigh the cost of capacity against the cost of innovative load control devices, and if the price of capacity is high, a market for such technology will emerge. However, there is a considerable threshold prior to the introduction of capacity subscription, caused by the implementation costs and complexity.</p><p>The conclusion on policies is thus that in an early stage after restructuring it may be appropriate to resort to the capacity obligation or payment method if the capacity balance is tight at the time of transition. For the medium-term, or if there is ample capacity initially, it is sensible to introduce proxy market prices to transfer the risk of a capacity deficit to market participants, with due attention being paid to the appropriate price level. Capacity subscription can be a long-term objective.</p>

The theme of this thesis is the supply of capacity during peak demand in restructured power systems. There are a number of reasons why there is uncertainty about whether an enegyonly electricity market (where generators are only paid for the energy produced) is able to ensure uninterrupted supply during peak load conditions. Much of the public debate in Europe has been about the present surplus generation capacity. However, in a truly competitive environment, it is hard to believe that seldom used capacity will be kept operational. This is illustrated by developments in Sweden. For this reason, the large surplus of generation capacity in the European Union may vanish much faster than generally assumed. In the USA, much of the debate has been about California. During the last three summers, California has occasionally experienced involuntary load shedding and prices have been very high during these periods. To some extent, the Californian situation illustrates the relevance of the subject of this thesis: in a deregulated system generators may not be willing to invest in peaking capacity that is only needed occasionally, even though prices are very high during these periods. A good solution to the problem of providing peaking power is pivotal to the success of power market restructuring. Solutions that fail to create the right incentives will result in unacceptable load shedding and can endanger the whole restructuring process. On the other hand, solutions that pay too much for investments in peaking power will lead to generation capacity surpluses and thus represent a societal loss. Why is peaking capacity a problematic issue in energy-only markets? Traditionally, probabilistic methods are applied to calculate the required generation capacity to obtain a desired level of reliability. In a centrally planned system, this level of generation capacity is developed in a least-cost manner. A single utility or central authorities can thus control the level of reliability directly. This is not possible in a market-based system, if suppliers are only paid for the energy produced. Under the assumption of certainty and continually varying prices, generators fully recover their variable and investment costs under ideal market conditions. When uncertainty is taken into account, generators will cover their expected costs. However, revenues will be extremely volatile, especially for peaking generators. Combined with a risk-averse attitude, it is unlikely that investments will be sufficient to maintain the traditional level of reliability in an energyonly market. Consequently, one would expect reserve margins to decline in such markets. This effect is very clear in Sweden that deregulated in 1996, and less explicit in a number of other cases like Norway, California and Alberta. Pricing and Consumer Preferences The theory of electricity pricing was originally developed for vertically integrated utilities, but elements from this theory are also valuable in a restructured context. Many authors have agreed on the presence of a capacity element in the optimal price during peak-load conditions, while price should equal marginal cost during low-load conditions. An important assumption is that prices have to be stable. More recently, spot pricing of electricity has been advocated. A number of papers have been written about how to efficiently include security considerations in the spot price. Because the availability of capacity cannot be directly controlled in an energy-only spot market, the probability of occasional capacity shortages increases. It is important to be prepared for this situation. The core of the problem is that demand is de facto inelastic in the short-term because of traditional tariff systems. It is shown that considerable economic gains are obtained when demand elasticity can be utilized, even if only minor shares of demand are elastic in the short-term. Better utilization of demand elasticity was also profitable in traditional systems, but after restructuring the gain is much larger: the alternative is not expensive generation but random rationing, which is unacceptable in modern society. It is possible to go one step further. Consumers have different preferences for the use of energy and reliability. Some consumers have a low tolerance about being disconnected, while others are more willing to accept this. This will be reflected by their willingness to pay for reliability. A better solution would emerge if consumers could buy electricity and reliability more or less as separate commodities, based on their preferences. In the context of pricing it should be pointed out that ”profile-based settlement” that allows small consumers to freely choose their supplier without hourly metering is detrimental with respect to the correct pricing of capacity. It should only be used in the initial phases of opening a market. Improved utilization of system resources Even in the short-term, demand and the availability of generation and transmission resources are uncertain. Therefore, it is necessary to have reserves available in a power system. When capacity becomes scarce, it is difficult to satisfy the reserve requirements. If these requirements are strict, the only possibility is to resort to what can be called ”preventive loadshedding” to satisfy the reserve requirements. This is obviously an expensive solution, but there are no obvious ways of balancing the (societal) cost of preventive load shedding against reduced system security. In this thesis, a model is developed for unit commitment and dispatch with a one-hour time horizon, with the objective of minimizing the sum of the operation and disruption costs, including the expected cost of system collapse. The model is run for the IEEE Reliability Test System. It is shown that under conditions where there is not enough capacity available to satisfy the reserve requirements, large cost savings can be obtained by optimizing the sum of the operation and disruption costs instead of using preventive load-shedding. In the model, it is also possible to directly target reliability indexes like the Loss of Load Probability or Expected Energy not Served. It is shown that increased reliability (in terms of the values of the indexes) can be obtained at a lower cost by targeting the indexes directly instead of resorting to reserve requirements. This is especially the case if flexible load-shedding routines are developed, making it possible to disconnect and reconnect the optimal amounts of load efficiently. The use of alternatives to fixed reserve requirements as a means to maintain system security does not solve the problem about how to ensure the availability of peaking capacity. However, in a situation with occasional capacity shortages, it gives the System Operator a tool to find the optimal balance between preventive load shedding and system security, which can result in significantly lower disruption costs in such cases. More research and development in this area is necessary to develop methods and tools that are suitable for large power systems. Ancillary Services Investment in peaking capacity is insufficient in restructured systems because expected revenues are too low or too uncertain. If generator revenues are increased, the situation improves. One way to obtain this is to create markets for ancillary services. In the thesis, a model is developed for a central-dispatch type of pool. In this model, markets for energy and three types of ancillary services are cleared simultaneously for 24 hours ahead. Market prices are such that volumes and prices are consistent with the market participants. self-dispatch decisions . i.e. given these prices, market participants would have chosen the same production of energy and ancillary services as the outcome of the optimization program. With this model, it is shown that markets for ancillary services increase generator revenues, but this effect is partly offset by lower energy prices. This shows that markets for ancillary services can contribute to improving the situation, but given the remaining uncertainty, this is hardly enough to solve the problem. Capacity Subscription Because consumers have preferences for two goods: electricity and reliability, they should ideally have the choice of purchasing the preferred amount of each of these. Traditionally this is not possible . reliability is a public good, produced or obtained by a central authority on behalf of all consumers. Technological progress is presently changing this. Capacity subscription is a method that allows consumers to choose their individual level of reliability, at the same time creating a true market for capacity. It is based on the concept of selfrationing. Consumers anticipate (for example on a seasonal basis) their need for capacity at the instant of system-wide peak demand. Based on this anticipation, they procure their desired level of capacity in a market, where generators offer their available capacity. Demand is limited to subscribed capacity by a fuse-like device that is activated when total demand exceeds total available generation. In this way, the capacity payment only influences the market when demand is close to installed capacity, and does not distort the energy price in other periods. Demand is not limited when there is ample capacity. Demand will never exceed supply, because it can be limited in an acceptable way when this situation occurs. Moreover, both consumers and suppliers can adapt to situations with scarce or ample capacity, and the price of capacity will reflect this situation. There is one problem with the method: as consumers do not reach their subscribed capacity simultaneously, there will be a capacity surplus at the instant the fuse-devices are activated. Two methods to solve this problem are analysed, and it is shown that the problem can be solved optimally by giving consumers who prefer this the opportunity to buy power in excess of their subscription on the spot market. Policy evaluation Six alternative policies to assess the peaking power problem are analysed based on the following criteria: - Static efficiency: the welfare-optimal match of consumption and supply - Dynamic efficiency: the ability to create incentives for innovation - Invisibility: with invisible strategies, each market actor pursues his or her own objectives without worrying about anyone else.s - Robustness: a robust policy is less sensitive to deviations from assumptions - Timeliness: the ability of a policy to be employed at the right time - Stakeholder equity: the degree to which all the involved parties are treated equitable - Corrigibility: the extent to which a policy can be corrected once it is employed - Acceptability: the degree to which the policy is acceptable to all parties - Simplicity: ceteris paribus simple strategies are preferable over more complicated strategies - Cost: the cost of implementing the policy - System security: the policy.s ability to obtain an acceptable level of system security The policies are, in short (an example is given in parentheses): - Capacity obligation: suppliers are obliged to keep sufficient capacity (PJM) - Fixed capacity payment: a fixed payment is offered for available capacity (Spain) - Dynamic capacity payment: capacity payment is based on the Loss of Load Probability (England and Wales) - Energy-only: no explicit payments or obligation (Scandinavia, California) - Proxy prices: very high administrative prices are used as a proxy to the Value of Lost Load when load shedding is necessary (Australia) - Capacity subscription: cf. the description above (not implemented) As could be expected, no single policy performs best on all criteria. The obligation and fixed payment methods do not perform well on market efficiency criteria, as essentially they are not market-based policies. The proxy prices policy is a reasonable policy on most criteria. It is easy, cheap and quick to implement. Because there is little experience with the method so far, there is some uncertainty with respect to if it is effective. One can anticipate that the threat of having to buy power at rationing prices will motivate market participants to avoid coming in a buying position in such cases, and that this will stimulate the adaptation of innovative solutions, especially on the demand side. The capacity subscription policy looks very promising on the issues of efficiency, robustness and system security. This is especially true for dynamic efficiency: consumers will weigh the cost of capacity against the cost of innovative load control devices, and if the price of capacity is high, a market for such technology will emerge. However, there is a considerable threshold prior to the introduction of capacity subscription, caused by the implementation costs and complexity. The conclusion on policies is thus that in an early stage after restructuring it may be appropriate to resort to the capacity obligation or payment method if the capacity balance is tight at the time of transition. For the medium-term, or if there is ample capacity initially, it is sensible to introduce proxy market prices to transfer the risk of a capacity deficit to market participants, with due attention being paid to the appropriate price level. Capacity subscription can be a long-term objective.

M.Sc.Eng. University of KwaZulu-Natal, Durban 2014.

Made available in DSpace on 2014-06-11T19:30:50Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-02-23Bitstream added on 2014-06-13T20:40:36Z : No. of bitstreams: 1 maciel_rs_dr_ilha.pdf: 1550413 bytes, checksum: b3a03ef6d2f87573564a7049ed54dd9a (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Dentre as profundas mudanças que os sistemas de distribuição de energia elétrica vêm experimentando nas últimas décadas, a crescente penetração da Geração Distribuída (GD) representa ainda uma série de desafios técnicos para as redes de distribuição tradicionalmente concebidas. Essa tendência na alteração do paradigma de concepção, planejamento e operação das redes de distribuição de energia elétrica tem suscitado a necessidade de inovação nas metodologias e ferramentas computacionais de análise. Assim, este trabalho procura investigar as potencialidades das meta-heurísticas de otimização multiobjetivo (OM) como ferramenta para a análise de impacto da penetração da GD nas redes de distribuição de média tensão. Esse esforço pode ser dividido em duas etapas: a primeira concentrada sobre as técnicas de solução de modelos de OM e a segunda dirigida para o estudo do impacto causado pela GD em aspectos técnicos da rede de distribuição, como nível de tensão, curto-circuito e capacidade, considerando-se o problema de planejamento da expansão das redes de distribuição. Quanto ao estudo das técnicas de OM, fez-se um conjunto de investigações sobre os conceitos de otimização multiobjetivo, os principais métodos baseados em meta-heurísticas e na aplicação de OM a problemas de sistemas de potência, especialmente os relacionados à inserção da GD nas redes de distribuição. Foram implementados os métodos Nondominated Sorting Genetic Algorithm II (NSGA-II), baseado em Algoritmos Genéticos, e Busca Tabu multiobjetivo (BTMO). Finalmente, desenvolveu-se no âmbito desta tese o algoritmo Multi- objective Evolutionary Particle Swarm Optimization (MEPSO) com o objetivo de explorar os ganhos de desempenho verificados com a meta-heurística híbrida... / The Distributed Generation (DG) plays an important role in the profound changes that distribution power systems are facing in the last decades. The impacts caused by high DG penetration are still a challenge for traditional distribution networks. Then, there is a need for innovation and development of computational tools for system analysis considering the new trends for designing, planning and operating distribution networks. This work investigates the potential of meta-heuristics for multi-objective optimization (MO) to evaluate the impact of the penetration of DG in medium voltage distribution networks. The research may be divided in two parts: firstly, the study is focused on the techniques for solving MO problems and the second part aimed to evaluate the impact of DG on technical aspects of the distribution network, such as voltage levels, short-circuit and current capacity, considering the problem of expansion planning of the distribution network. Regarding the study of the techniques of MO, the concepts of multi-objective optimization was investigated as well as the main meta- heuristic based methods and the application of the MO to power systems problems, especially those related to the integration of DG in distribution. Two methods were implemented: the Nondominated Sorting Genetic Algorithm II (NSGA-II), based on Genetic Algorithms and a multi-objective Tabu Search (MOTS). Finally, the algorithm of a Multi-objective Evolutionary Particle Swarm Optimization (MEPSO) was developed within this thesis in order to exploit the performance gains observed with the hybrid meta-heuristic Evolutionary Particle Swarm Optimization (EPSO) in single-objective optimization problems. Concerning the study of the impact of DG, a methodology for analysis of the Pareto front was proposed which allows, in addition to obtaining... (Complete abstract click electronic access below)

Made available in DSpace on 2014-06-11T19:30:51Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-04-23Bitstream added on 2014-06-13T18:40:59Z : No. of bitstreams: 1 baquero_jff_dr_ilha.pdf: 928776 bytes, checksum: 14beda1a12c4b74205593d8475f64232 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O problema do planejamento de sistemas de distribuição de energia elétrica consiste em determinar as mudanças que precisam ser feitas no sistema visando atender as condições de demanda futura, respeitando os critérios técnicos de operação e segurança, tudo isto sob um mínimo custo econômico (no caso da otimização monoobjetivo). A modelagem do problema de planejamento da expansão de sistemas de distribuição inclui a repotenciação de subestações existentes, a alocação e dimensionamento de novas subestações, o recondutoramento de alimentadores existentes, a construção e seleção do tipo de cabo para alimentadores novos e a seleção da topologia do sistema (reconfiguração). Além disso, o modelo considera que a expansão do sistema pode ser executada em vários estágios, propondo assim uma formulação dinâmica do problema de planejamento. É apresentada neste trabalho uma estratégia de decomposição para dividir o problema no subproblema da seleção das subestações e na solução de problemas de reconfiguração e recondutoramento dependentes. São desenvolvidos algoritmos heurísticos, que combinados com a metaheurística Busca Tabu, permitem uma exploração eficiente do espaço de busca. A estratégia de decomposição mencionada permite o uso da programação paralela, conseguindo diminuir o tempo de processamento. O método proposto é testado usando casos de grande porte da literatura, mostrando um excelente desempenho / The distribution system expansion planning problem consists of to determine the investments that need to be made in the system to meet future demand conditions, satisfying technical criteria for operation and safety, all under a minimum economic cost (in the case of mono-objective optimization). The modeling of the planning problem includes the expansion of existing substations, the allocation and design of new substations, the reconductoring of existent feeders, the selection of the type of conductor for new feeders and the selection of the system topology (reconfiguration). Furthermore, the model assumes that the expansion of the system can be performed in several stages, thus it is proposed dynamic planning problem formulation. In this paper work, it is presented a decomposition strategy to separate the problem into the subproblems of selection of the substations, reconfiguration and selection of the conductor feeders. Heuristic algorithms are developed, which combined with the Tabu Search metaheuristic, allow an efficient exploration of the space of search. The decomposition strategy aforementioned allows the use of parallel programming, achieving reduced processing time. The proposed method is tested using large cases in the literature, showing excellent performance