大型同步发电机三相短路下的短路冲击电流研究  

Research on the short-circuit impulse current of three-phase short-circuit in large synchronous generator

作　　者：马凯悦 王建全[1] MA Kai-yue;WANG Jian-quan(School of Electrical Engineering,Zhejiang University,Hangzhou 310027,China)

机构地区：[1]浙江大学电气工程学院,浙江杭州310027

出　　处：《能源工程》2020年第4期88-93,共6页Energy Engineering

摘　　要：短路冲击电流是最恶劣短路条件下,短路电流的最大可能瞬时值。一般认为在同步发电机空载运行情况下,转子位置角处于180°时刻发生三相短路,半个周波后出现短路冲击电流。电力系统短路实用计算中,短路冲击电流取冲击系数与短路瞬间次暂态电流的乘积。实际情况是发电机短路冲击电流将随着负载的变化而变化,短路实用计算结果往往不够精确。文中对短路电流公式,冲击系数进行了分析;通过短路电流公式寻优与PSCAD/EMTDC建立同步发电机三相短路模型仿真,研究不同负载下短路冲击电流的变化,对短路实用计算的冲击系数提出修正方法。最后,通过算例验证了该方法的合理性。Short-circuit impulse current is the maximum possible instantaneous value of short circuit current under the most adverse short circuit circumstance.It is generally considered that for a no-load synchronous generator,if a three-phase short-circuit fault happens when the rotor mechanical angle is 180 degree,the short-circuit impulse current occurs.In practical short circuit calculation of power system,the short-circuit impulse current is the product of the impulse coefficient and the sub-transient short-circuit current.However,the practical calculation is often not accurate enough because of the fact that the short-circuit impulse current changes with load.The formula of short circuit current and impulse coefficient were analyzed in this paper.The variation of the short-circuit impulse current under different load conditions was studied by optimizing the traditional short-circuit current formula with PSO and establishing the three-phase short-circuit model of a synchronous generator with PSCAD/EMTDC.Moreover an impulse coefficient correction method for practical short circuit calculation was proposed.Finally,the rationality of the proposed impulse coefficient correction method was verified by test examples.

关 键 词：同步发电机 三相短路 短路冲击电流 冲击系数 

分 类 号：TM31[电气工程—电机]