基于无功电流波形相关性的逆变型电源电站送出线故障方向判别原理

Principle of Fault Direction Identification for the Outgoing Line of Inverter Power Station Based on the Correlation of Reactive Current Waveforms

受逆变型电源弱馈、电源阻抗变化等故障特性的影响,使用正序电压或记忆电压作为极化电压的方向元件可能会出现误动作的情况。为了解决该问题,提出了一种基于无功电流波形相关性的故障方向判别原理。利用故障期间逆变型电源与同步发电机正序电流的差异,通过计算无功电流测量波形与参考波形的相关系数判断故障方向。当逆变型电源侧发生正向故障时,无功电流测量波形与参考波形基本一致;发生反向故障时,无功电流测量波形与参考波形存在显著差异。仿真结果表明:提出的保护判据在不同的故障情况下都能够可靠、灵敏地判断故障方向。

Due to the influence of fault characteristics such as weak feed and impedance change of inverter-interfaced renewable energy source(IIRES),malfunctions may occur in directional element when the positive sequence voltage or memory voltage is utilized as polarization voltages.In order to solve this problem,a fault direction criterion based on the correlation of positive sequence reactive current waveform is proposed in this paper.According to the difference of positive sequence dynamic reactive current between IIRES and synchronous generator during fault,the fault direction is determined by calculating the correlation coefficient between measurement waveform and reference waveform of dynamic reactive current.If the forward fault occurs at the IIRES side,the reactive power current measurement waveform and reference waveform are almost the same.If the reverse fault occurs at the IIRES side,the reactive power current measurement waveform and reference waveform are different.The simulation results indicate that the proposed directional element can reliably and sensitively determine the fault direction under different fault conditions.