Within the literature review the diploma thesis deals with the definition of renewable resources, subjects of electricity market and the system of payments for the support of renewable energy. The aim of this diploma thesis is the analysis of the legislative environment before 2013 and in 2013. The practical part of my diploma thesis is focused on the development of energy legislation, relating to renewable resources in the Czech Republic but it also deals with foreign suggestions for energy legislation in this field. Considering the legislative change of the payments for the support of renewable energy, the reporting of electricity production resources and evidence of electricity production, which is based on the law 165/2012 legal code, the diploma thesis describes new information and data flows between subjects of electricity market and the way of payment for invoices for supported production of electricity as well. The diploma thesis characterizes the impact of legislative changes on the producers of electricity from the renewable resources. The diploma thesis is concerned with significantly discussed topics in the field of renewable resources. These topics are related to producers of electricity from the renewable resources and to consumers of electricity as well. The topics are especially about the amount of the payments for the support of solar energy and about establishment of the duty on solar energy. This diploma thesis can make the orientation in the legislative changes in 2013 for producers of electricity from the renewable resources easier. The diploma thesis can also help the electricity producers from the renewable resources in the necessary activities for the payment of supported production of electricity.

Este trabalho tem como objetivo avaliar o balanço econômico de uma política de incentivos para as fontes de energia renovável, analisando em particular o caso das PCHs (Pequenas Centrais Hidrelétrica) inseridas no Proinfa, o Programa de Incentivo às Fontes Alternativas de Energia Elétrica. A análise é desenvolvida tomando por base a internalização de custos e benefícios para a sociedade do referido Programa. Dentre os benefícios, estão destacados o desenvolvimento de uma fonte alternativa de energia que diminui os impactos ambientais devidos às emissões de gases poluentes, tal como o CO2, NOx o SO2 e o material particulado. Dentre seus custos, o imposto a ser cobrado se faz necessário para que programas dessa natureza se realizem. Para tanto, a revisão da literatura se concentra em assuntos concernentes à avaliação de programas de incentivos, bem como sobre o desenho de políticas de subsídio e das formas que a economia encontra para lidar com externalidades. Em seguida, analisam-se as estruturas propostas de incentivos, verificando-se, à luz da teoria, se essas estruturas são apropriadas aos seus fins e procedendo-se a uma análise de custo/benefício destas. / This work has the objective to evaluate the economic balance of an incentive policy for renewable energy source (RES), in particular it analyses the SHP (Small Hydropower Plant) case into the Context of Proinfa, the Brazilian alternative electrical energy source incentive program. This analysis is developed considering the point of view of internalizing the costs and benefits for the society. Among the benefits could be highlighted the development of a RES that reduces environmental impacts caused by pollutant gas emissions, such as CO2, NOx, SOx and particulated material, among the costs is the tax necessary to support this kind of program. To achieve this objective, the literature revision was focused on subjects related to evaluation of an incentive program as well as on the design of subsidy policies and how the economy deals with externalities. Also it is analyzed the incentives framework proposed, verifying based on the economic theory, if this framework is suitable to its own aims, and at the end it is proceed a cost benefit analysis of this structure.

Made available in DSpace on 2016-08-17T14:52:49Z (GMT). No. of bitstreams: 1 Aniceto_de_Deus_Pereira_Neto.pdf: 1168768 bytes, checksum: adc4488efe00f3201345ff8a783ac6bb (MD5) Previous issue date: 2008-07-25 / The restructuring and deregulation of electricity markets has caused signi¯cant changes in electrical power systems in several countries. This process has result in a market-based competition by creating an open market environment. In this new environment each generation company runs the Unit Commitment to maximize their pro¯ts, and have no obligation to meet the energy and spinning reserve demands, as happened in the past. With this new structure, the Unit Commitment problem has received special attention, since generation companies in actual model always seek the maximum pro¯t without concern to serve all demands. On the other hand, there is the system operator, which always seeks to optimize overall system at the lowest cost. So, there are two di®erent situations into this competitive market environment: generators seeking the maximum bene¯t without concern to the system security operating, and independent system operator seeking always operate the system safely and at less cost. This work presents the mathematical models and the solution Unit Commitment problem, which was implemented considering two view points: the generation companies and the system independent operator views. Moreover, an auction model is extended to PRD in a horizon of 24 hours. This auction model simulates the interaction between generators and system operator to meet demands and security of the system. The idea is to stimulate the players to o®er products to energy (primary) and reserve (Ancilar Service) markets using only prices o®ered by market operator for each product. This iterative process is ¯nalized when generators supply su±cient to meet demand, and not cause any violation on °ow limits in transmission lines. The solution method proposed for Unit Commitment is based on evolution strategies and Lagrange Relaxation, resulting in a robust hybrid algorithm. The method have been validated in a test system composed of 6 buses, 7 transmission lines and 10 generating units. The results showed the e±ciency of the hybrid model proposed, which was able to solve the unit commitment problem in its various models considered here. / A reestruturação dos mercados de energia elétrica provocou mudanças significativas nos sistemas elétricos de potência de diversos países. Neste novo ambiente, cada empresa de geração executa individualmente o Pré-Despacho para maximizar seus benefícios financeiros, e não têm a obrigação em atender suas demandas de potência e reserva girante, como acontecia no modelo tradicional. Por outro lado existe o operador do sistema, o qual sempre busca a otimização global do sistema ao menor custo. Assim, têm-se duas situações distintas neste ambiente competitivo: os geradores buscando o máximo benefício sem preocupação com a segurança operativa do sistema, e o operador independente buscando sempre operar o sistema de forma segura e ao menor custo. Este trabalho apresenta as modelagens matemáticas e a solução do Pré- Despacho executado sob os dois pontos de vista: dos agentes de geração e do operador independente do sistema. Além do mais, um modelo de leilão é estendido para o PRD num horizonte de 24 horas. Este modelo simula a interação entre os agentes de geração e o operador do sistema na busca por uma solução única que concilie o interesse de ambos. A idéia é estimular os agentes geradores a ofertarem os produtos para os mercados de energia (primário) e de reserva (Serviço Ancilar) mediante oferta de preços pelo operador do mercado para os respectivos produtos. Esse procedimento iterativo é finalizado quando a oferta dos geradores for suficiente para atender completamente a demanda e, não provocar violações em nenhum limite de fuxos na malha de transmissão. O método de solução proposto para o Pré-Despacho é baseado em estratégias evolutivas e Relaxação de Lagrange, resultando em um modelo híbrido robusto. Os modelos e técnicas foram validados em um sistema teste composto por 6 barras, 7 linhas de transmissão e 10 unidades geradoras. Os resultados obtidos demonstraram a eficiência do método de solução, o qual se mostrou capaz de resolver o problema de Pré-Despacho nas suas diversas modelagens utilizadas.

In the last two decades, more than half of the countries in the world have introduced a reform process in their power industries and billions of dollars have been spent on liberalizing electricity markets around the world. This thesis presents a doctoral research concerned with the cross-country empirical analysis of the electricity market reforms. The thesis is in three-paper format; that is, we present three independent but related stand-alone papers. The first paper focuses on the impact of power market reforms on electricity price-cost margins and industrial/residential price ratios. It investigates this issue by looking at the impact of the electricity industry reforms on residential and industrial electricity price-cost margins and their effect on industrial/residential price ratios. Using panel data from 63 developed and developing countries covering the period 1982–2009, empirical models are developed and analysed. The results suggest that each individual reform step has different impact on price-cost margins and industrial/residential price ratios for each consumer and country group. That is to say, our findings imply that similar reform steps may have different impacts in different countries, which supports the idea that reform prescription for a specific country cannot easily be transferred to another one with similar success. The second paper explores whether the question of why some countries are able to implement more extensive reforms is closely related to the question of why some countries have better institutions than others. It analyses this question by using an empirical econometric model based on Poisson regression with cross-section data covering 51 states in US, 13 provinces in Canada and 51 other countries. The study concludes that both the background of the chairperson and the minister/governor and institutional endowments of a country are important determinants of how far reforms have gone in a country. Considering the fact that ideological considerations, political composition of governments and educational/professional background of leaders have played and will play a crucial role throughout the reform process; the third paper attempts to discover the impact of political economic variables on the liberalization process in electricity markets. It develops and analyses empirical models using panel data from 55 developed and developing countries covering the period 1975–2010. The results suggest that a portion of the differences in the reform experiences of reforming countries in the past three decades can be explained by differences in the political structure, in the ideology of the government and in the professional and educational backgrounds of the political leaders.

Local electricity markets can be defined broadly as 'future electricity market designs involving domestic customers, demand-side response and energy storage'. Like current deregulated electricity markets, these localised derivations present specific stochastic optimisation problems in which the dynamic and random nature of the market is intertwined with the physical needs of its participants. Moreover, the types of contracts and constraints in this setting are such that 'games' naturally emerge between the agents. Advanced modelling techniques beyond classical mathematical finance are therefore key to their analysis. This thesis aims to study contracts in these local electricity markets using the mathematical theories of stochastic optimal control and games. Chapter 1 motivates the research, provides an overview of the electricity market in Great Britain, and summarises the content of this thesis. It introduces three problems which are studied later in the thesis: a simple control problem involving demand-side management for domestic customers, and two examples of games within local electricity markets, one of them involving energy storage. Chapter 2 then reviews the literature most relevant to the topics discussed in this work. Chapter 3 investigates how electric space heating loads can be made responsive to time varying prices in an electricity spot market. The problem is formulated mathematically within the framework of deterministic optimal control, and is analysed using methods such as Pontryagin's Maximum Principle and Dynamic Programming. Numerical simulations are provided to illustrate how the control strategies perform on real market data. The problem of Chapter 3 is reformulated in Chapter 4 as one of optimal switching in discrete-time. A martingale approach is used to establish the existence of an optimal strategy in a very general setup, and also provides an algorithm for computing the value function and the optimal strategy. The theory is exemplified by a numerical example for the motivating problem. Chapter 5 then continues the study of finite horizon optimal switching problems, but in continuous time. It also uses martingale methods to prove the existence of an optimal strategy in a fairly general model. Chapter 6 introduces a mathematical model for a game contingent claim between an electricity supplier and generator described in the introduction. A theory for using optimal switching to solve such games is developed and subsequently evidenced by a numerical example. An optimal switching formulation of the aforementioned game contingent claim is provided for an abstract Markovian model of the electricity market. The final chapter studies a balancing services contract between an electricity transmission system operator (SO) and the owner of an electric energy storage device (battery operator or BO). The objectives of the SO and BO are combined in a non-zero sum stochastic differential game where one player (BO) uses a classic control with continuous effects, whereas the other player (SO) uses an impulse control (discontinuous effects). A verification theorem proving the existence of Nash equilibria in this game is obtained by recursion on the solutions to Hamilton-Jacobi-Bellman variational PDEs associated with non-zero sum controller-stopper games.

The main focus of this thesis is to find out what factors have the biggest influence on the price of electricity for household consumers in the European Union in the context of creating the internal electricity market in the EU. By means of the cluster analysis six EU Member States have been selected according to the following criteria: electricity consumption, electricity production, and the price of electricity. As a result of that Belgium, the Czech Republic, Estonia, Hungary, Malta and Sweden have been selected. Consequently, the regression analysis has been carried out to find out what factors influence the electricity prices in every country individually. The independent variables are mainly various sources of electricity production. It was found out those renewable resources most influent the electricity price for households in Belgium, Estonia, Hungary, and Sweden. Nevertheless, in the context of Europe 2020 strategy and the formation of the European energy market, one of the European Commission's objectives is to increase the share of renewable sources in the production of electricity in the EU Member States. Therefore, it will bring about higher prices of electricity, which goes against the Commission's effort to decrease the price of electricity for households through the liberalisation of electricity and the creation of the internal electricity market.

Renewable cannibalization refers to the phenomenon where the increasing penetration of zeromarginal cost renewable energy sources, such as solar and wind power, leads to a decline in their market value. By extension, this threatens to reduce investment incentives in wind and solar. Based on theory of supply and demand, the extent to which cannibalization is experienced should increase as the penetration of wind and solar increases. Since electricity prices, and therefore cannibalization, are set with considerations to domestic system dynamics, regulations and policies, cannibalization research are typically limited to investigate it for a specific country or region. For this thesis, Spain has been chosen for the case study. Coupling an already high penetration of both wind and solar with ambitious goals for wind and solar capacity expansion, Spain constitutes an interesting case study for cannibalization research. The investigation is centered around two factors, the market capturing price (MCP) and the cannibalization factor (CF). The MCP is the generation weighted electricity price and measures absolute cannibalization, while the CF is the ratio between the MCP and the average electricity price, thus constituting a relative cannibalization measurement. These will be calculated using hourly day-ahead wind and solar forecasts, and day-ahead electricity prices. A time series econometric study is then conducted to quantify the cannibalization effect together with potentially influential factor that, in theory, should be the driving factors behind the cannibalization phenomenon. To investigate dynamic affects across these factors, temporal regressions are conducted. In these regressions, data is isolated in different groups based on their characteristics. Furthermore, carbon pricing and granular guarantees of origin (GOs) are investigated and assessed based on their potential for alleviating the effect of cannibalization.  The study finds that both wind and solar cannibalizes their own market values, and that cannibalization occurs across technologies. The results indicate that there is a negative marginal relation between wind and solar infeed, suggesting the presence of both self-cannibalization and cross-cannibalization effects on their respective MCPs. The same can be said for the CF of solar, for which there is a negative marginal effect with the infeed of wind and solar. These statements hold true across all ranges of wind and solar penetration investigated in the temporal regression analysis. Moreover, the negative relations increase as the penetration range increases, indicating that cannibalization effects are stronger at high renewable penetration. For wind power, this is not entirely the case. Although the regression results yielded a low coefficient of determination (R2), indicating weak explanatory power in the regressions, it is possible to interpret whether the marginal effects are positive or negative. The temporal regression results indicate that there is a positive marginal effect between solar infeed and the CF of wind when the penetration of solar is lower than 10%. Thus, considering the ambitious wind and solar capacity targets of Spain, the economic viability of wind and solar could be threatened. Furthermore, the results from the study indicate that although carbon pricing helps increasing the MCP for both wind and solar by adding an increment to the day-ahead price, it reduces the CF. Furthermore, carbon pricing is a limited tool for alleviating cannibalization, considering that it requires. Thus, once the system is fully decarbonized, carbon pricing is rendered obsolete. On the contrary, the implementation of granular (hourly) GOs provide extra revenue in addition to the revenue from sold electricity. Furthermore, its immediate effect is that it increases the revenue while not impacting the price of electricity. Thus, it helps counteracting both absolute and relative cannibalization effects. / Förnybar kannibalisering hänvisar till fenomenet där en ökande markandspenetration av förnybar energi med noll marginalkostnad, så som vind- och solkraft, leder till en minskning i deras marknadsvärde. Detta hotar i förlängningen att minska incitament för fortsatta investeringar inom vind- och solkraft. Baserat på teorier om utbud och efterfrågan bör graden av kannibalisering öka i takt med att marknadspenetrationen av vind- och solenergi ökar inom ett givet system. Eftersom elpriser, och därmed graden av kannibalisering, beror på nationella dynamiker inom kraftsystemet, föreskrifter och riktlinjer, utförs ofta studier om kannibaliserade effekter inom förnybar energi från fallstudier inom ett land eller en regions system. I denna avhandling har Spanien valt som fallstudie. Med en redan hög grad av förnybart inom elsystemet, samt ambitiösa mål för fortsatt utbyggnad av vind- och solkraft, utgör Spanien en intressant fallstudie för forskning om förnybar kannibalisering.  Undersökningen utgår från två faktorer; det produktionsviktade elpriset (MCP) och kannibaliseringsfaktorn (CF). MCP utgör en absolut faktor och är det produktionsviktade elpriset för en viss teknologi, medan CF utgör ett mått på relativ kannibalisering och beräknas genom att dividera MCP med det genomsnittliga elpriset. Dessa två faktorer beräknas genom att använda timvisa prognoser från dagen-före marknaden för produktion av vind- och solkraft, samt priser från spotmarknaden. Därefter utförs en ekonometrisk studie baserad på tidseriedata för att kvantifiera de kannibaliserande effekterna med avseende på utomstående faktorer som bör kunna ses som drivkrafter bakom kannibaliseringsfenomenet. Dessutom undersöks och bedöms koldioxidprissättning och timvisa ursprungsgarantier baserat på deras förmåga att lindra effekterna av kannibalisering i Spanien. Studien visar att både vind- och solenergi kannibaliserar sina egna marknadsvärden, samt att kannibalisering sker mellan kraftslag. Resultaten indikerar att det finns en negativ marginaleffekt mellan produktion av vind- och solel, vilket tyder på förekomsten av både självkannibaliserande och korskannibaliserande effekter på deras respektive produktionsviktade elpriser (MCP). Samma kan sägas gälla för solkraftens kannibaliseringsfaktor (CF), där det finns en tydlig negativ marginaleffekt gentemot produktion av vind- och solel. Dessa påståenden stämmer över alla intervall av vind- och solpenetration som undersökts i den temporala regressionsanalysen. Dessutom ökar de negativa relationerna desto högre intervall som avses, vilket tyder på att kannibaliseringseffekten är starkare vid hög penetration av förnybar energi. För vindkraft stämmer inte detta helt. Även om regressionsresultaten gav en låg determinationskoefficient (R2), vilket indikerar svag förklarande kraft i regressionerna, är det möjligt att tolka om marginaleffekterna är positiva eller negativa. De temporala regressionsresultaten visar att det finns en positiv marginal- effekt mellan produktionen av solel och CF för vindkraft när solkraft utgör mindre än 10% av den dagliga produktionen. Med tanke på Spaniens ambitiösa mål för vind- och solkapacitet kan den ekonomiska livskraften för vind- och solenergi hotas. Vidare visar resultaten från studien att även om koldioxidprissättning hjälper till att öka MCP för både vind- och solenergi genom att skapa ett tillägg på spotmarknadspriset, minskar det CF. Dessutom är koldioxidprissättning ett begränsat verktyg för att lindra kannibalisering, med tanke på att det kräver. När systemet är fullständigt avkarboniserat blir koldioxidprissättning överflödig. Å andra sidan ger implementeringen av granulära (timvisa) ursprungsgarantier (GOs) extra intäkter utöver intäkterna från såld el. Dessutom ökar det omedelbart intäkterna utan att påverka elpriset. På så sätt hjälper det till att motverka både absoluta och relativa kannibaliseringseffekter.

The electricity market is facing major changes in the coming years, with major production facilities that must be replaced and climate targets that are required to be met. The approach to the targets in the electricity market has been to invest in renewable energy, mostly in the form of wind power. However, it is an intermittent production type where production depends on weather conditions and planning cannot be predetermined. As a result, the price of electricity has varied a lot in recent years and has also become very low, which causes profitability challenges for the electricity producers. One consequence is the closure of four nuclear reactors due to lack of profitability. This creates a more uncertain environment for the Swedish industry, which is dependent on both low electricity prices and reliable power supply. A way to counter this has been the “Energy Agreement”, that partly aims to promote the use of nuclear power for their total technical service life. The electrical system will change until 2030 in many ways, but how this will go is difficult to predict. By creating three different scenarios that reflect likely future changes, it has been possible to draw conclusions about what is necessary to change for the electricity system to be robust and competitive in the future. These scenarios consider wind power, active nuclear reactors, export opportunities and future electricity prices. These three scenarios have included identification of the most important parameters that need to be changed or considered by 2030. These parameters have been divided into price issues, delivery security and taxes with subsequent proposals. The most important items under these are to maintain the marginal cost based pricing model, create incentives for flexibility of electricity users and for manufacturers to provide the power grid with inertia. These require special focus to create a robust and flexible system, but remaining points are required as well to handle these issues. These points resulted in a framework that should form the basis for decision making. The framework should also be used in its entirety to analyze situations that may arise during the transition from today's market to the future's renewable electricity system. / Elmarknaden står inför stora förändringar de kommande åren, med stora produktionsanläggningar som måste ersättas och klimatmål som förväntas uppfyllas. Tillvägagångssättet har på den svenska elektricitetsmarknaden varit att satsa på förnybar energi, mestadels i form av vindkraft. Det är dock ett intermittent produktionsslag där produktionen är väderberoende och inte går att planera. Elpriset har till följd av detta varierat mycket under de senaste åren och blivit väldigt lågt, något som orsakar lönsamhetsproblem för producenterna. Ett resultat av detta är stängningen av fyra kärnreaktorer till följd av bristande lönsamhet, vilket skapar en oroligare situation för den svenska industrin som är beroende av både låga elpris och en tillförlitlig eltillförsel. Ett sätt att möta konflikten mellan producenternas olönsamhet och industrins krav är Energiöverenskommelsen, som delvis syftar till att göra kärnkraften med konkurrenskraftig. Elsystemet kommer att förändras till 2030 på många vis, men hur detta kommer gå till är svårt att förutsäga. Genom att skapa tre olika scenarion som speglar troliga framtida förändringar, har det gått att dra slutsatser om vad som är nödvändigt att förändra för att elsystemet ska vara robust och konkurrenskraftigt även i framtiden. Dessa scenarion tar hänsyn till vindkraftsutbyggnad, aktiva kärnreaktorer, exportmöjligheter och framtida elpris. Dessa tre scenarion har inburit identifiering av de viktigaste parametrar som måste förändras eller tas i beaktande till 2030. Dessa har delats upp i prisfrågor, leveranssäkerhet samt skatter med efterföljande förslag. De viktigaste punkterna under dessa är att behålla marginalprissättningen, skapa incitament för flexibilitet hos elanvändare och för producenter att tillhandahålla svängmassa. Dessa kräver särskilt fokus för att skapa ett robust och flexibelt system, men resterande punkter behövs för att hantera dessa frågor. Dessa punkter resulterade i ett ramverk som bör ligga till grund för beslutsprocesser. Ramverket bör också användas i sin helhet för att analysera situationer som kan uppstå under omställningen från dagens marknad till framtidens förnybara elsystem.

In the context of electricity, arbitrage trading involves taking advantage of existing price variations within electricity markets. The report conducted financial modelling for energy storage systems and demand-side load management for electricity arbitrage trading in single-family homes. The analysis included two different energy storage systems: a thermal energy storage system and a battery energy storage system. Additionally, electricity spot cost reduction was compared between electricity arbitrage trading and traditional energy efficiency measures such as air-to-water and ground-source heat pumps. The report's findings indicated that air-to-water and ground-source heat pumps emerged as the most economically viable choices for reducing electricity spot costs, irrespective of the studied electricity price area. The thermal energy storage system, employing an insulated hot water storage tank, ranked the third most efficient in achieving cost savings. The battery energy storage system, represented by a lithium home battery system, demonstrated the lowest rate of cost saving among the analyzed energy efficiency measures.  The financial modelling highlighted the economic potential for thermal energy storage systems, particularly in southern Sweden's electricity price areas SE3 and SE4. On the other hand, no economically viable options for battery energy storage systems were identified, regardless of the studied electricity price area. As a results, the report recommends utilizing thermal energy storage systems and implementing demand-side load management as strategies to hedge against future electricity price volatility.

[pt] A possível mudança no paradigma de formação de preço no Brasil do modelo vigente por custos auditados para o modelo por oferta, com o objetivo de modernizar o Setor Elétrico e buscar práticas que incentivem a competição, implica a necessidade de estudos prévios para auxiliar o processo de transição e a definição do desenho de mercado adequado à realidade brasileira. Nesse sentido, o uso de modelos de equilíbrio, notadamente o Equilíbrio de Nash, desponta como uma poderosa ferramenta ex-ante que permite analisar o comportamento dos competidores para identificar possíveis ineficiências a serem mitigadas. Com esse fim, o presente trabalho modela o processo decisório de ofertas ótimas de um competidor em um mercado de energia elétrica de dia-seguinte de base hidrotérmica por um modelo de otimização binível, possibilitando a identificação do Equilíbrio de Nash do mercado através de um algoritmo baseado em Gauss-Seidel. Adicionalmente, o método é aplicado a dois experimentos numéricos: a um sistema-teste de três barras e a um caso representativo do sistema brasileiro completo, permitindo a análise do comportamento dos competidores a partir da comparação dos resultados com os modelos de Custos Auditados e Equilíbrio Competitivo. Foram observados os impactos das afluências e das cascatas de usinas hidrelétricas de múltiplos proprietários nas receitas e, consequentemente, no comportamento dos competidores. Por fim, foi verificada a ocorrência de competição exclusivamente pelas quantidades, além da prática de retenção de ofertas por parte dos competidores para a modificação do preço de equilíbrio de mercado, aumentando suas receitas. / [en] The potential shift in Brazil s energy pricing paradigm from the current Audited Costs model to the Bid-Bases model, with the aim of modernizing the electricity sector and seeking practices that encourage competition, implies the need for preliminary studies to assist the transition process and define the appropriate market design for the Brazilian reality. In this sense, the use of equilibrium models, notably the Nash Equilibrium, emerges as a powerful ex-ante tool that allows the analysis of competitors behavior to identify possible inefficiencies to be mitigated.To this end, this thesis models the optimal bidding decision process of a competitor in a hydrothermal day-ahead electricity market using a bilevel optimization model, enabling the identification of the Nash Equilibrium of the market through an algorithm based on the Gauss-Seidel. Additionally, the method is applied to two numerical experiments: a three-bus test system and a representative case of the complete Brazilian system, allowing for the analysis of competitors behavior by comparing the results with the Audited Costsand Competitive Equilibrium models. The impacts of water inflows and hydro plants in cascade with distinct ownership on revenues and consequently competitors behavior were observed. Finally, the occurrence of competition exclusively in quantities was verified, as well as the practice of quantity bids retention by competitors in order to modify the market equilibrium price, increasing their revenues.