Análise de métodos anti-ilhamento ativos para sistemas fotovoltaicos
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Data
2022-02-17
Autores
Hyakutake, Leonardo Ryudi
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
A ampliação dos sistemas de geração distribuída no país traz alguns problemas que devem ser sanados e dentre eles, um de suma importância é o ilhamento. Por motivo de segurança, os sistemas de geração distribuída devem detectar o ilhamento e interromper o fornecimento de energia para a rede elétrica. Os métodos de detecção de ilhamento, denominados métodos anti-ilhamento, são divididos em dois grupos, sendo os métodos passivos compostos por observação e comparação de parâmetros normatizados, e os métodos ativos, os quais atuam no controle do inversor para gerar algum distúrbio para deslocar o equilíbrio de potência do sistema formado por inversor e carga. Tal equilíbrio pode levar o inversor a operar ilhado, mesmo com a rede de distribuição de energia desenergizada. No sentido de entender a metodologia dos métodos ativos de anti-ilhamento, neste trabalho são estudados os desempenhos de quatro destes métodos, com modelos feitos no ambiente Simulink, a partir de um inversor monofásico, utilizando como fonte a energia solar fotovoltaica. A avaliação do desempenho é feita a partir das zonas de não-detecção (ZND) de cada método anti-ilhamento. Os parâmetros escolhidos para avaliar as ZND foram o fator de qualidade da carga e frequência de ressonância (Qf x f0). Os modelos dos métodos anti-ilhamento são executados para diferentes condições de carga RLC, utilizando diferentes valores para Qf e f0, escolhendo pontos fora, dentro e sobre a fronteira da ZND, com o intuito de observar as zonas de não detecção de cada método. Os resultados dos testes são dados por meios de figuras que mostram a mudança de frequência após desconexão da rede e comparando os resultados dos quatro métodos analisados, aqueles que utilizam realimentação positiva mostram ser mais eficientes, pois possuem menores ZND utilizando menores distúrbios.
The expansion of distributed generation systems in the country brings some problems that must be solve and among them, one of paramount importance is the islanding. For safety reasons, distributed generation systems must detect the islanding and interrupt the power supply to the electricity grid. The methods of islanding detection, called anti-islanding methods, are divided into two groups, and passive methods, which are composed of observation and comparison of standardized parameters. And the active methods, in the other group, act in the control of the inverter to generate some disturbance to displace the power balance of the system formed by inverter and load. Such a balance can led the inverter to operate islanded, even with the power distribution network de-energized. To understand the methodology of active anti-islanding methods, in this paper the performances of four of these methods are studied, with models made in the Simulink, from a single-phase inverter, using photovoltaic solar energy as a source. The performance evaluation is made from the non-detection zones (NDZ) of each anti-islanding method. The parameters chosen to evaluate the NDZ were the load quality factor and resonance frequency (Qf x f0). The models of the anti-islanding methods run for different RLC load conditions, using different values for Qf and f0, choosing points outside, inside and on the boundary of the NDZ, to observe the non-detection zones of each method. The test results are given by means of figures that show the frequency change after disconnection from the network and comparing the results of the four analyzed methods, those that use positive feedback show to be more efficient, as they have smaller NDZ using smaller disturbances.
The expansion of distributed generation systems in the country brings some problems that must be solve and among them, one of paramount importance is the islanding. For safety reasons, distributed generation systems must detect the islanding and interrupt the power supply to the electricity grid. The methods of islanding detection, called anti-islanding methods, are divided into two groups, and passive methods, which are composed of observation and comparison of standardized parameters. And the active methods, in the other group, act in the control of the inverter to generate some disturbance to displace the power balance of the system formed by inverter and load. Such a balance can led the inverter to operate islanded, even with the power distribution network de-energized. To understand the methodology of active anti-islanding methods, in this paper the performances of four of these methods are studied, with models made in the Simulink, from a single-phase inverter, using photovoltaic solar energy as a source. The performance evaluation is made from the non-detection zones (NDZ) of each anti-islanding method. The parameters chosen to evaluate the NDZ were the load quality factor and resonance frequency (Qf x f0). The models of the anti-islanding methods run for different RLC load conditions, using different values for Qf and f0, choosing points outside, inside and on the boundary of the NDZ, to observe the non-detection zones of each method. The test results are given by means of figures that show the frequency change after disconnection from the network and comparing the results of the four analyzed methods, those that use positive feedback show to be more efficient, as they have smaller NDZ using smaller disturbances.
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Palavras-chave
Anti-ilhamento, Geração distribuída, Ilhamento, Energia fotovoltaica, Anti-islanding, Distributed generation, Islanding, Photovoltaic energy