中性点不接地配电系统并联铁磁谐振状态频域解析方法

Frequency domain analytical method for parallel ferroresonance state of distribution system with neutral point ungrounded

近年来,配电网大范围使用电缆代替架空线路,对地分布电容增大使得系统远超参数谐振区域,但当单相接地尤其间歇性弧光接地故障消失时,电压互感器饱和后引发的铁磁谐振现象时有发生。本文基于中性点不接地中压配电系统并联等效模型,利用描述函数法计算谐振时的线路参数状态,分析了电流与磁链间关系和非线性方程之间的规律,利用增量法求出其谐振状态条件下解的稳定性判据,构建了中性点不接地中压配电系统并联铁磁谐振状态频域解析方法,为分析配电网铁磁谐振频率分布提供了理论依据。仿真结果证明了该方法的有效性。

In recent years,cables have been widely used instead of overhead lines in the distribution network,and the increase of the distributed capacitance to the ground makes the system far beyond the parametric resonance region.However,when the single-phase grounding fault,especially the intermittent arc grounding fault,disappears,the ferroresonance phenomenon caused by PT saturation occurs from time to time.Non-ground neutral medium voltage power distribution system is based on the parallel equivalent model,using the describing function method to calculate the resonant state of the line parameters,analyzes the relationship between electric current and magnetic flux and the laws between the nonlinear equations.The incremental method is used to find out the resonance state under the condition of the stability criterion of solution,non-ground neutral medium voltage power distribution system is constructed in parallel ferro-resonance state frequency domain analysis method,to analysis provides theory basis for ferromagnetic resonance frequency distribution of the distribution network.Simulation results show the effectiveness of this method.