高压电缆护套环流泄漏电流分量的分析与计算

Analysis and Calculation for Leakage Current Component of Circulating Current in High Voltage Cable Sheath

高压电缆金属护套环流是感应电流分量与泄漏电流分量的叠加,目前,感应电流分量计算较为成熟,而泄漏电流分量的计算存在不足,影响最终环流计算结果与相关故障诊断效果。为此,提出了高压电缆护套环流泄漏电流分量的计算方法。以电缆“线芯—护套”的π型等效电路为基础,建立了求解护套环流泄漏电流分量的等值电路,同时计及泄漏电流的分流作用与线芯泄漏电流所产生的环流,基于迭代法得到最终的泄漏电流分量。利用电磁暂态仿真软件ATP-EMTP搭建了一字型敷设的电缆模型,结果表明:在不同段长组合及负荷电流下,该方法计算结果与仿真值的相对误差在2%以内,相较于现有方法,准确性有较大提高。所提方法可以较好地解释轻载时出现环流超标的原因;对交叉互联系统故障诊断样本数据的生成有一定的参考作用。

The circulating current of metal sheath in high voltage cable is the superposition of induced current component and leakage current component.At present,the calculation of induced current component is relatively mature,but the calculation of leakage current component is insufficient,which affects the final circulating current calculation result and the related fault diagnosis effect.For this reason,a calculation method for leakage current component of sheath circulating current in high voltage cable was proposed.Based on the π-type equivalent circuit of"core—sheath",an equivalent circuit for solving leakage current component of sheath circulating current was established,which take into account the shunting effect of leakage current and circulating current generated by leakage current of cable core.The final leakage current component was obtained based on the iterative method.A cable model with a linear arrangement was built using ATP-EMTP software.The results show that the relative deviation between calculation result and simulation value of this method is within 2% under different length combinations and load currents,compared with existing method,the accuracy is greatly improved.This method can better explain the reason of excessive circulating current at light load,and has a certain reference for the generation of sample data for fault diagnosis of cross-connected systems.