基于单端量的主动式直流配网故障识别

Active Fault Identification of DC Power Network Based on Single-terminal Quantity

基于模块化多电平变换器的柔性直流配电网,当其发生直流侧故障后,换流器闭锁极快,故障暂态持续时间极短,从而导致依靠故障暂态信息的保护难以正常动作。利用全桥换流器可控性较高的特点,提出一种基于单端特征电流幅值的故障识别方案。在故障限流后,从一端换流站主动注入特征信号。故障极特征信号在故障点因过渡电阻而产生分流,于是到达对端的特征电流信号幅值会衰减。利用健全极与故障极特征电流信号幅值的差异进行故障识别。因仅利用单端电流量进行判别,所以该方案的判据简捷、可靠性较高。仿真结果证明了该方法的有效性。

When a DC side fault occurs in a flexible DC distribution network based on a modular multilevel converter,the converter is locked very fast,and the fault transient duration is extremely short,which makes it difficult for the protection based on the fault transient information to operate normally.Taking advantage of the high controllability of the full-bridge converter,a fault identification scheme based on the single-ended characteristic current amplitude is proposed,in which the characteristic signal is actively injected from one converter station after the fault current is limited,and the amplitude of the characteristic current signal reaching the opposite terminal is attenuated as the characteristic signal experiences the shunt effect of the transition resistance at the fault point.Fault identification is carried out by using the difference of characteristic current signal amplitude between sound pole and fault pole.The simulation results show that the scheme only uses the single-ended current to judge on the basis of ensuring the identification accuracy,which simplifies the criterion and improves the reliability.