考虑分布电容影响的煤矿供电系统漏电故障分析及定值整定

Analysis and setting of leakage faults in the coal mine power supply system considering the influence of distributed capacitance

为进一步提高煤矿供电系统的安全可靠性,通过对煤矿低压和高压供电系统发生漏电故障特点进行研究,利用戴维南等效得到漏电流计算电路,分析漏电阻、系统总分布电容对漏电流的影响以及消弧线圈不同补偿方式下漏电流的特征差异。由于线路分布电容的存在,漏电后形成的漏电电流有效值远大于仅考虑绝缘电阻时的情况,在保证人身触电安全的前提下,给出了煤矿供电系统线路总分布电容限值,提出了考虑分布电容影响的漏电保护方案,根据方案可求得漏电保护动作整定值和保证人身安全的动作时间范围,实现考虑分布电容影响的煤矿供电系统漏电故障定值整定。

To enhance the safety and reliability of the coal mine power supply system,this paper examines the characteristics of leakage faults in both low and high-voltage coal mine power supply system.a circuit for calculating leakage current is derived by using Thevenin equivalence.The influence of leakage resistance,total distributed capacitance on leakage current,and the distinctive features of leakage current under different compensation modes of arc suppression coil are analyzed.Due to the distributed capacitance present in the line,the effective value of leakage current post-fault is significantly larger than when only considering insulation resistance.Ensuring that the safety current doesn′t exceed 30 mA during human contact,the maximum allowable distributed capacitance for coal mine power supply system is proposed to ensure personal safety.A leakage protection scheme considering the influence of distributed capacitance is also introduced.Based on this scheme,the appropriate setting value of leakage protection and the required operational time frame to ensure personal safety can be determined,which could effectively avoid personal electric shock accident in coal mine power supply system.