基于工频突变量阻抗测量的新型孤岛检测方法

Islanding detection based on power-frequency variation impedance

为了能够对新能源场站集中式接入的情况进行有效的孤岛检测,提出一种基于工频突变量阻抗测量的新型孤岛检测方法。新方法利用孤岛发生瞬间的工频突变量电流和工频突变量电压求取工频突变量阻抗,根据其大小进行孤岛检测,并通过辅助判据有效避免误判的情况。仿真结果表明,新方法能够在孤岛发生后2个周期内迅速检测出孤岛,且不存在检测盲区,当系统发生短路故障或负荷波动等扰动时,新方法不会发生误判,具有较高的可靠性。另外,新方法是一种被动式孤岛检测法,不影响正常运行时的电能质量。

An effective method of islanding detection based on the power-frequency variation impedance（ΔZ =ΔU / ΔI） is proposed for the grid-connected centralized new-energy station,which calculates ΔZ during islanding based on the variations of power-frequency current and voltage and identifies the islanding according to the calculated ΔZ. An additional criterion is given to avoid false identification. Simulative results show that,the proposed method can quickly detect the islanding within 2 periods without any dead-zone and has higher reliability without false identification during short circuit faults and load fluctuations. It is the passive islanding detection method and has no effect on the power quality of system in normal operation.