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.
作者
马凯悦
王建全
MA Kai-yue;WANG Jian-quan(School of Electrical Engineering,Zhejiang University,Hangzhou 310027,China)
出处
《能源工程》
2020年第4期88-93,共6页
Energy Engineering
关键词
同步发电机
三相短路
短路冲击电流
冲击系数
synchronous generator
three-phase short circuit
impulse current
impulse coefficient
