配电网同杆并架线路接地故障中性点电压计算分析

基于同杆并架线路的谐振接地配电网,若一个系统发生单相接地故障,该系统中性点电压会通过耦合电容传递给非故障系统,可能导致消弧线圈的误动作。针对此问题,通过理论分析得到影响非故障系统中性点位移电压的主要因素及变化趋势;建立准确的电缆出线为主及架空线(对地电容不平衡)为主的变电站计算模型,通过计算得到单相接地故障与非故障时两种系统中性点电压值。分析得如果同杆并架线路不超过5 km且其他系统参数设置恰当时,系统不会发生耦合电容引起的消弧线圈误动。

Calculation and Analysis on Ground-fault Neutral Point Voltage of Distribution Lines on Same Pole in Distribution Network

For the distribution lines on same pole in a distribution network with neutral grounding,when single-phase grounding fault occurs in one system,the neutral point voltage transmits to the other normal system via coupling capacitor of distribution line on the same pole,and the voltage may result in the Peterson coil misoperation.In order to solve the problem,the main factors that affect the neutral point displacement voltage of the normal system are analyzed theoretically in this paper,the variations of the factors are obtained,and models of respective cable feeder lines substation and overhead lines substation are established.Therefore,the neutral point voltages of single-phase grounding fault and normal state are obtained by the models.If the length of the distribution lines on same pole is less than 5 km and other system parameters are set suitably,the Peterson coil misoperation induced by coupling capacitor doesn’t occur in the system.