Desligamento ótimo de linhas de transmissão considerando contingências N–1
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Data
2022-09-16
Autores
Sanches, Aline de Paula
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Com o crescimento da população e o avanço da tecnologia houve um grande aumento no consumo de energia elétrica. Dessa forma os sistemas elétricos passaram a operar com altos níveis de carregamento, levando a problemas como sobrecargas em linhas de transmissão e violações de limites da magnitude de tensão. Um sistema de transmissão muito carregado pode limitar a geração em unidades mais econômicas, levando à necessidade de despachar unidades geradoras com custos mais elevados, resultando em ineficiência do mercado. Neste contexto, neste trabalho será abordado o problema de desligamento ótimo de linhas de transmissão (DOLT) para otimizar o custo de operação de um sistema elétrico. Assim, o primeiro tópico abordado na pesquisa consiste em desenvolver uma estratégia para reduzir o número de linhas candidatas ao desligamento, de forma a reduzir o esforço computacional para resolver o problema de DOLT mantendo a qualidade da solução. Outro tópico abordado foi desenvolver um modelo matemático que encontre uma topologia ótima considerando restrições de segurança do tipo N–1 para linhas de transmissão. A topologia de operação do sistema de transmissão deve manter pelo menos o nível de segurança da rede sem desligamento de linhas e atingir melhores custos de operação com o DOLT. Na formulação desses problemas foram utilizados modelos de programação linear inteira mista e formulações disjuntivas considerando a operação DC do sistema. Os modelos matemáticos foram implementados na linguagem de modelagem matemática AMPL e resolvidos com o solver comercial CPLEX. Testes foram realizados no sistema IEEE de 24 barras, sistema sul brasileiro de 41 barras e sistema colombiano de 92 barras. Os resultados obtidos mostram que a proposta de redução do número de linhas candidatas ao desligamento no problema de DOLT foi capaz de fornecer soluções com qualidade próxima às soluções obtidas sem considerar redução. Com relação ao tópico de DOLT considerando segurança N–1 para linhas de transmissão, foram obtidas soluções que mantém ou melhoram o nível de segurança da rede e apresentam melhores custos de operação.
With the growth of the population and the advancement of technology, there has been a great increase in the electricity consumption. In this way, the electrical systems started to work with high loading levels, leading to problems such as transmission line overloads and voltage limits violations. A heavily loaded transmission system can limit generation on more economical units, leading to the need to dispatch higher cost generating units, resulting in market inefficiency. In this context, this work will address the problem of optimal transmission switching (OTS), to optimize the operating cost of an electrical system. Thus, the first topic addressed in the research consists of developing a strategy to reduce the number of transmission lines that are candidate for switching, in order to reduce the computational effort to solve the OTS problem while maintaining the quality of the solution. Another topic addressed was the development of a mathematical model that finds an optimal topology considering N–1 security constraints for transmission lines. The operation topology of the transmission system must maintain at least the security level of the network without disconnecting lines and achieve better operating costs with the OTS. In the formulation of these problems, mixed-integer linear programming models and disjunctive formulations were used considering the DC operation of the system. The mathematical models were implemented in the AMPL mathematical modeling language and solved with the CPLEX commercial solver. Tests were carried out using the IEEE 24-bus system, the southern Brazilian 41-bus system, and the Colombian 92-bus system. The results obtained show that the proposal to reduce the number of candidate lines for switching in the OTS problem was able to provide solutions with quality close to the obtained solutions without considering the reduction. With regard to the topic of OTS considering N–1 security for transmission lines, solutions were obtained maintaining or improving the level of network security and presenting better operating costs.
With the growth of the population and the advancement of technology, there has been a great increase in the electricity consumption. In this way, the electrical systems started to work with high loading levels, leading to problems such as transmission line overloads and voltage limits violations. A heavily loaded transmission system can limit generation on more economical units, leading to the need to dispatch higher cost generating units, resulting in market inefficiency. In this context, this work will address the problem of optimal transmission switching (OTS), to optimize the operating cost of an electrical system. Thus, the first topic addressed in the research consists of developing a strategy to reduce the number of transmission lines that are candidate for switching, in order to reduce the computational effort to solve the OTS problem while maintaining the quality of the solution. Another topic addressed was the development of a mathematical model that finds an optimal topology considering N–1 security constraints for transmission lines. The operation topology of the transmission system must maintain at least the security level of the network without disconnecting lines and achieve better operating costs with the OTS. In the formulation of these problems, mixed-integer linear programming models and disjunctive formulations were used considering the DC operation of the system. The mathematical models were implemented in the AMPL mathematical modeling language and solved with the CPLEX commercial solver. Tests were carried out using the IEEE 24-bus system, the southern Brazilian 41-bus system, and the Colombian 92-bus system. The results obtained show that the proposal to reduce the number of candidate lines for switching in the OTS problem was able to provide solutions with quality close to the obtained solutions without considering the reduction. With regard to the topic of OTS considering N–1 security for transmission lines, solutions were obtained maintaining or improving the level of network security and presenting better operating costs.
Descrição
Palavras-chave
Modelo linear disjuntivo, Otimização, Programação linear inteira mista, Redução do espaço de busca, Segurança N–1, Transformadores defasadores, Linear disjunctive model, Mixed-integer linear programming, Optimization, Phase-shift transformers, Reduced search space, N–1 security for transmission lines