配电网DG对反时限过电流保护的影响

针对分布式电源(DG)接入配电网后可能引起保护误动作的问题,分析了分布式电源接入配电网后对短路电流的影响,推导了各种情况下短路电流的计算公式,分析了反时限过电流保护误动作的可能性,对一个10 k V配电网的反时限过电流保护的启动电流和时间特性系数进行了整定计算,仿真分析了短路电流和动作时限的变化及反时限过电流保护误动的可能性.结果表明,仅当DG所在线路上DG上游发生故障时,处于故障点和DG之间的保护发生误动作的可能性较大.

Distributed generation impact on inverse-time over-current protection

The integration of distributed generation(DG) into the distribution network may incur the falseprotection action by inverse-time over-current protection.The DG impact on short-circuit current in the distribution system is analyzed,and the formula of short-circuit current under various conditions are deduced,then the possibility offalse action by inverse-time over-current protection is analyzed.A 10 kV distribution system with DG is used to calculate the starting current and time characteristics of inverse-time over-current protection,and simulate the short-circuit current and the action time,as well as the false actionpossibility of inverse-time over-current protection.The results show that the possibility of the false action is high with location between the fault point and the DG when the short-circuit occur in the DG''s upstream.