配电网馈线零序电流随过补偿度动态调节的变化特性分析

Analysis on Zero-sequence Current Variation Characteristic for Feeders of Distribution Network at Different Residual Current Compensation Factors

分析了过补偿度动态调节过程中,不同故障过渡电阻及馈线对地电容参数下故障馈线和非故障馈线零序电流的变化特性。建立了馈线线路零序电流关系表达式,在过补偿区域、欠补偿区域和全区域内动态调节过补偿度,给出了多场景下馈线零序电流变化曲线。分析结果表明:经过渡电阻单相接地故障下,在过补偿度小于零且大于故障线路对地电容占母线所有出线对地电容之和比例的相反数区间,故障线路与非故障线路零序电流幅值变化特性一致;在过补偿度大于零区间,当过渡电阻大于边界值时,两者变化特性一致,该边界值与馈线线路对地电容成反比。研究结果为残流增量法接地故障选线的改进提供了重要的理论依据。

Zero sequence current variation charaeteristics of faulty and healthy distribution feeders with different fault resistances and earth capacities during the changing process of residual current compensation faetors are analyzed. Firstly, the relational expression for zero sequence current is given. Secondly, zero sequence current variation curves of distribution feeders are presented for multi parameter scenarios with residual current compensation factor varying in over compensation, under compensation and whole regions. The results show that once single line to ground fault through resistance occurs, the zero sequence current variation characteristic of faulty feeder is consistent with that of healthy feeder under the following conditions： （1）residual current compensation factor is less than zero but greater than the opposite number of the ratio of fauhy feeder＇s ground capacitance to total ground capacitance of all feeders; （2） fault resistance is greater than the boundary value which is inversely proportional to the ground capacitance of the feeder while the residual current compensation factor is greater than zero. The analysis results provide an important theoretieal basis to the remnant current increment method.