基于相分量模型的变电站短路电流分流系数计算

发变电站内发生短路故障时真正引起危害的是入地故障电流,而不是短路故障电流;当前已有的数值算法及软件或存在一定的技术性门槛,或在表征系统方面存在不足。提出一种适用于不同电压等级的复杂电力系统分流系数计算方法,推导并拓展了基于相分量的变压器导纳模型,将其应用于回路电流法,计算出电流分布及分流系数;通过与商业软件CDEGS进行比较,验证了该算法的正确性。作为应用,还定量分析了考虑变压器故障侧和非故障侧同时分流对分流系数的影响,指出了准确计算分流系数时变压器是不可或缺的系统元件。

A Calculation Method of Fault Current Distribution and Shunt Coefficient in Substation Based on Phase-coordinate Model

While a short circuit fault happens in a power substation,it is the current diffusing into ground that actually causes the safeness trouble instead of the fault current.Most of the current numerical methods and software are required to cross the technical threshold,or have limitations in characterizing the power system.The paper presented a numerical method to calculate the shunt coefficient for the complex power system with different voltage levels,and derived the admittance matrix for a phase-coordinate transformer model which is applicable for the loop current method.The method was verified by comparison with commercial software CDEGS.It has been applied to analyzing the effect of the transformer,and the result shows that the transformer is an essential system component for the calculation of shunt coefficient.