合闸策略对变压器励磁涌流零序分量的影响

Effect of switching strategy on zero-sequence component of transformer inrush currents

在关合空载三相变压器时,三相励磁涌流不对称导致的零序分量容易引起变压器本身甚至线路的零序电流继电保护装置误动作,使得电力系统供电中断。文中分析了三相变压器励磁涌流的产生机理,推导出励磁涌流及其零序分量的解析表达式,采用理论分析与仿真相结合的方法研究不同合闸控制策略对于励磁涌流零序分量的抑制情况。结果表明,分相合闸策略在同时抑制励磁涌流及其零序分量方面比同步合闸策略更有优势。

When switching a three‐phase no‐load power transformer ,the zero‐sequence component re‐sulting from the asymmetry of three phase inrush currents tends to mislead the zero‐sequence current protection apparatus of the transformer itself or even the adjacent lines ,and poses a hazard to the reli‐ability of the power system .This paper analyzes the mechanism of three‐phase transformer’s inrush currents ,deduces the formulas of inrush current and its zero‐sequence component ,and compares the suppressions of zero‐sequence current under different switching control strategies by theoretical analy‐sis and simulation .The results show that the phase‐control switching method has a better effect on restraining both of the inrush current and its zero‐sequence component than the synchronous one .