一种基于电荷电压波形相似性的小电流接地故障检测方法

A Method for Detection of Small Current Grounding Faults Based on Waveform Similarity of Charge and Voltage

选取可靠的特征量是提高中性点非直接接地系统中单相接地故障检测准确率的关键所在。在分析了界内单相接地故障发生时刻零序电压与变化的系统电容电荷波形相似性,以及界外单相接地故障发生时刻零序电压与变化的系统电容电荷波形相似性的基础之上,提出了一种适用于小电流接地故障检测的方法。该方法利用单相接地故障发生时刻零序电流实时值计算出该时刻变化的系统电容电荷实时值,并计算出此刻零序电压与变化的系统电容电荷波形的相似系数,根据此相似系数具有明显离散性的特征对单相接地故障的界内界外属性做出判断。

Selecting a reliable characteristic quantity is the key to improve the detection accuracy of single-phase grounding fault in neutral indirectly grounding system.On the basis of analyzing the similarity of waveform between zero sequence voltage and the change of system capacitance charge at the time of a singlephase grounding fault occurs within the boundary,as well as the similarity of waveform between zero sequence voltage and the change of system capacitance charge at the time of single-phase grounding fault occurring outside the boundary,a method suitable for the detection of small current grounding fault is proposed,which uses the realtime value of zero sequence current at the time of a single-phase grounding fault to calculate the real-time value of the system capacitance charge changes at the time of a single-phase grounding fault,and to calculate the similarity coefficient of waveform between zero sequence voltage and the system capacitance charge changes at the time.Based on the obvious discreteness of the similarity coefficient,the inside and outside attributes of a single-phase grounding fault are judged.