Evaluating the performance of external fault ride-through solutions used in wind farms with fixed speed induction generators when facing unbalanced faults

Abstract

Resumo: Na sequência da integração da energia eólica em larga escala foram estabelecidos códigos de rede pelos vários operadores de sistema, exigindo que os parques eólicos permaneçam em serviço durante e após a ocorrência de defeitos na rede a montante. Nos parques eólicos equipados com sistemas de velocidade constante este requisito pode ser assegurado pela instalação, no ponto de interligação à rede, de equipamento de compensação dinâmica de potência reactiva, controlado como fonte de tensão, sendo as funções de controlo baseadas em medidas efectuadas no ponto de interligação relativamente às componentes directas da tensão e da corrente. Como a adopção deste tipo de soluções externas é adequada ao funcionamento do sistema em regime equilibrado, este artigo foca a avaliação do desempenho da solução no caso da ocorrência de defeitos assimétricos.Os resultados obtidos através das simulações dinâmicas evidenciam o aparecimento de sobre tensões nas fases não afectadas pelo defeito que poderão colocar o parque eólico fora de serviço. Abstract:The continuous growth of wind energy integration on electrical networks has led many utilities to impose fault ride-through capability to wind farms. This means that wind turbines must remain connected to the system during severe fault occurrence. Regarding the existing wind farms equipped with fixed speed induction generators directly connected to the grid, fault ride-through capability is commonly assisted with dynamic compensation devices, such as DSTATCOM units.These power electronic devices are controlled for voltage regulation purposes and behave like a balanced three-phase voltage source converter since commonly used control techniques are based only on the positive sequence of both voltage and current measured at its connection point. These control techniques are suitable only when compensation devices are operated under balanced conditions and therefore its performance when facing unbalanced faults needs to be evaluated. This paper tackles with this subject and the results obtained through numerical simulations demonstrate that over voltages can arise on non faulty phases leading to the wind farm disconnection. Palavras

Probabilistic Analysis for Maximizing the Grid Integration of Wind Power Generation

“…These dual variables are associated with the equality constraints of the DC power flow equations. In mathematical terms (1) where is the dual variable associated to the transmission circuit connecting buses to and , where is the objective function and is the injected power of bus . When is different from zero, the circuits involved in the wind curtailment events B and C can be detected, making it possible to obtain yearly statistics for each circuit, such as the probability distribution of the total wind power curtailed when the circuit is limiting the usage of the total wind power available.…”

Management and control systems for large scale integration of renewable energy sources into the electrical networks

“…FSIG is a consumer of reactive power and needs additional equipment to provide fast control of reactive power, such as Static Var Compensation (SVC) devices and STATic synchronous COMpensators (STATCOM). Also, FRT capability can be assisted by external static compensation devices usually connected at the PCC [11]. Also, it would be beneficial to install FACTS is several strategic buses in order to mitigate the impact of short-circuits taking place in the network [8].…”