零序直流选择性漏电保护原理分析

对近期提出的克服电网分布电容影响小电流接地选线的零序直流选择性保护原理作了理论分析.按照检测整流半桥导通的不同时段,建立工频周期内三时段的正弦电路模型,用相量法分析检测电流.并在各时段将其转换为瞬时正弦值对时间求取平均值.理论分析表明,检测电流选择性好,受电网电容影响小,理论计算与实验检测曲线在漏电支路绝缘电阻接近动作值段一致性程度高.

Study of Selective Leakage Protection Principle Based on Zero Sequence Directive Current

This paper analyses the existing zero sequence directive current selective leakage protection principle which is to surmount the effect of distributed capacitance on it. According to the different period of time in the conducting state of half-wave rectifier bridge circuit, the sinusoidal circuit model of three zones is established in the cycle of fundamental frequency. The detected currents based on vector technique is explained, and the average value can be obtained by transforming these detected currents to instantaneously sinusoidal forms. Through the aforementioned theory analysis, it shows that the perfect selectivity of the detected currents as well as the less influence of the capacitance on it and keeps high consistency of the insulated resistance close to action point on the leakage branch compared the theory calculation with the testing detected curve.