分析了反时限过电流保护的动作特性,对一个10 kV配电网的反时限过电流保护的起动电流和时间特性系数进行了整定计算,计算了分布式电源接入配电网后短路电流和动作时限的变化,对比不含分布式电源的计算结果,得出结论:分布式电源的接入,对上游的故障影响较小;分布式电源下游发生故障时,对下游的故障短路电流起助增作用,将使其动作速度变快,而上游保护的动作时限将变长,作为远后备保护可能失去意义,严重的情况下,可能会拒动.%The characteristics of the inverse-time over-current protection are analyzed. The starting current and the time characteristic coefficient of 10kV distribution system are calculated. The fault current results of distribution system with and without distributed generation are calculated and compared. The results are as following: the distributed power supply has little effect. The access of distributedgeneration has little effect on the upstream fault. When the downstream fault occurs, the fault current in the upatream protection can be reduced and the current in the downstream protection can be enlarged. So, the time delay of the upstream relay becomes longer and loses meaning as far-back protection.
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