直流分量对变压器差动保护影响的仿真分析

Simulation and Analysis on Transformer Differential Protection Affected by Direct Current Component

介绍了几种电力系统中产生直流分量的因素,设计了励磁涌流产生模型与叠加直流分量的仿真模型,分析了直流分量对电流互感器(TA)暂态传变特性的影响,并通过空载合闸投入变压器同时流入直流分量的仿真,研究TA传变异常对励磁涌流判据的影响。研究结果表明,直流分量将改变TA传变特性,二次侧电流波形发生畸变,对励磁涌流闭锁二次谐波制动、间断角等判据产生影响,易引起变压器差动保护误动。

Introduction was made to several kinds of factors producing the direct current component in power system.This paper designed the model producing excitation surge current and the simulated model of superposition direct current component,and analyzed the impacts of transient state transmission transformer characteristic on current transformers.Via the simulation of the influx direct current component when no-load closing input the transformer,this paper studied on the impacts of current transformers transmission transformer abnormity on the criterion of excitation surge current.The research results show that the direct current component changes the characteristics of current transformers transmission transformer and the secondary side current waveforms are distorted,which will have impacts on the second harmonic brake and discontinuous angle criterion of excitation surge current shutting,to give rise to the transformer differential protection misoperation.