消弧线圈并联小电阻系统接地故障灵活处理策略

Grounding Fault Processing Strategy in Petersen Coil Paralleled Small Resistance Grounding System

随着对配电网接地方式和接地故障处理问题的重视,国内部分配电网出现了消弧线圈并联小电阻接地方式,给配电网接地故障处理技术带来了新的机遇与挑战。中性点经消弧线圈并联小电阻接地,能实现多数接地故障自动熄弧与永久接地故障的可靠保护,兼顾了2种接地方式的优点。但频繁投切并联小电阻可能造成过电流冲击,且考虑到并联电阻热容量限制与建设维护成本,应尽可能减少电阻投入次数。提出一种接地故障灵活处理策略,首先利用故障自身电气量实现接地选线,并对该结果进行可信度评估,仅在过渡电阻低于设定标准且选线结果不可信时,投入并联小电阻进行二次保护。该策略能有效减少并联小电阻的投入次数,节约成套装置的建设维护成本。

With the emphasis on neutral grounding method and grounding fault handling problem,Petersen coil paralleled small resistance has appeared in some domestic distribution networks,which brings new opportunities and challenges to the distribution network ground fault processing strategy.The neutral point is grounded by the arc suppression coil paralleled small resistance,which can make majority of arc grounding fault automatic extinguish and achieve reliable protection of permanent grounding fault,holding the advantages of both types of grounding methods.However,switching the resistance frequently may cause overcurrent surge to the distribution network.Considering the limitation of parallel resistance heat capacity and construction and maintenance costs,the number of resistance input should be reduced as much as possible.In this paper, a grounding fault processing strategy is proposed,which uses the fault’s own electrical quantity to achieve grounding line selection,and evaluates the reliability of the result.The resistance will be switched for secondary protection when the transition resistance is lower than the set standard and the line selection result is not credible.This strategy can effectively reduce the number of inputs of paralleled small resistance and save construction and maintenance costs of the equipment.