基于暂态相电流特征分析的故障选线新方法

Novel Method of Fault Line Selection Based on Characteristic Analysis of Transient Phase-current

为解决小电流接地系统单相接地故障时选线效果不佳的问题,详细分析了故障线路与非故障线路各相电流突变量及故障相电流频率分布特征。可知故障线路故障相与非故障相突变量波形差别较大,故障相暂态信号集中的频段较低;而非故障线路各相突变量幅值相同,波形一致,故障相暂态信号集中频段较高。为此,提出了综合利用相电流突变量及重心频率双重判据的故障选线方法,并借助故障特征距离将二者有效地结合起来,两种判据相互补充,进一步提高了选线的裕度。大量仿真分析表明,该方法在经高阻接地、故障初始角较小时均有较好的效果,具有适用性好、选线可靠、抗干扰能力强的特点。

In order to solve the problem of poor effect of fault line selection when a single-phase grounding fault occurs in the neutral indirect ground system,the distribution characteristics of fault component of current in every phase on the fault lines and non-fault lines and the phase-current frequency are analyzed in detail. It is shown that the difference be-tween waveforms of fault components in fault phase and non-fault phase on the fault line are obvious,and the frequency band where transient signals gather is lower for fault phase. However,the amplitudes of fault components in every phase on the non-fault line are the same,their waveforms agree with each other,and the frequency band where transient sig-nals gather is higher for fault phase. Therefore,a method of fault line selection is proposed in this paper,which uses fault components of phase-current and the frequency of gravity center as two criterions. With fault characteristic dis-tance,these two criterions can complement with each other,which can further improve the margin. Simulation results show that the method has better effects when a high-resistance grounding fault occurs in the context of small initial an-gle. Moreover,it has good applicability,reliable selection and strong anti-interference ability.