谐振接地系统高阻接地故障能量机理分析

Analysis of energy mechanism of high resistance grounding fault in resonant grounding system

配电线路高阻接地故障经常发生,利用能量的故障方向检测方法对于高阻接地故障具有独特的优势,传统认为其检测的暂态能量只是线路电阻、对地导纳与消弧线圈消耗的有功损耗,该结论不够准确,因此故障方向检测方法应需完善。通过对谐振接地系统在高阻接地故障下的故障点上游及下游线路的能量特征进行分析,发现故障发生后,线路对地电容与消弧线圈电感在暂态时间内会从故障点吸收能量,并且会一直用这部分能量进行交换;在故障下游检测点测得下游线路对地电容所储能量,能量值恒大于等于零;在故障上游检测点测得消弧线圈电感与背后线路对地电容所储能量总和,该部分能量绝大多数不会被释放,幅值较大、能量值恒小于零。根据以上特点可判断故障方向,完善了谐振接地系统高阻接地故障的能量机理分析,提高了高阻接地故障方向检测的可靠性。仿真数据验证了理论分析的正确性。

High-resistance ground faults in distribution lines occur from time to time.The fault detection algorithm using energy has unique advantages for high-resistance ground faults.Traditionally,the transient energy detected is only the active power consumed by line resistance,ground admittance and arc suppression coils,this conclusion is not accurate enough,so the method of fault direction detection should be improved.This paper analyzes the energy characteristics of the upstream and downstream lines of the fault point of the resonant grounding system under high resistance faults,we found that after the fault occurs,the line-to-ground capacitance and the arc suppression coil inductance will absorb energy from the fault point during the transient time,and will always use this part of the energy for mutual exchange.The downstream detection point of the fault is mainly the energy stored in the downstream line-to-ground capacitance,and the value is always greater than or equal to zero;while the upstream detection point of the fault is mainly measures the sum of the energy stored on the line-to-ground capacitance from the inductance of the arc suppression coil and the back line,most of this part of the energy will not be released,the amplitude value is larger and always less than zero.Based on the above characteristics,the fault direction can be judged,the related theory of the fault energy of the resonant grounding system is improved,and the reliability of the high-resistance fault detection is improved.The simulation data verifies the correctness of the theoretical analysis.