高阻抗变压器涌流的特殊性比较分析

Comparative Analysis of Particularity for Inrush Current Generated by High-impedance Transformer

近年来高阻抗变压器空投时零序过流保护误动的事故频繁发生,文中围绕高阻抗变压器涌流的特殊性展开研究。首先明晰了变压器'绕组排布—磁通分布—等值电路参数'的对应关系以及励磁涌流产生机理。根据高压绕组内置型高阻抗变压器、低压绕组串联电抗型高阻抗变压器与普通结构型常规阻抗变压器的结构差异阐释了等值电路中自漏感和空心电感等参数的差异。基于参数差异,从理论上分析比较了三者涌流的特殊性:相同条件下,内置型高阻抗变压器的励磁涌流幅值大于串联电抗型高阻抗变压器和普通结构型常规阻抗变压器。考虑三角绕组环流影响后,串联电抗型高阻抗变压器的原方涌流幅值大于普通结构型常规阻抗变压器;三者涌流衰减均很缓慢,相对而言内置型高阻抗变压器较另两个略快。仿真结果验证了所得结论的正确性。

In recent years,zero-sequence over-current protections misoperate frequently when the high-impedance transformers are energized.This paper focuses on the particularity of inrush currents of high-impedance transformer.Firstly,the relationship of'winding structure-flux distribution-equivalent circuit parameters'and the mechanism of the magnetizing inrush current are clarified.According to the structural differences among the high-impedance transformer with high-voltage winding built-in(T-Hin),the high-impedance transformer with inductance connected in series at low-voltage winding(T-Lse)and the traditional impedance transformer with ordinary structure(T-Tra),the parameter differences such as self-leakage inductance and air-core inductance in the equivalent circuit are explained.According to the parameter differences,the particularity of inrush currents generated by three kinds of transformers is theoretically analyzed and compared.Under the same condition,the inrush current amplitude of T-Hin is greater than that of T-Lse and T-Tra.When considering the influence of the circulation current of delta winding,the primary winding current of T-Lse is larger than that of T-Tra.The three inrush currents decay slowly,the inrush current of T-Hin is slightly faster than the other two relatively.The conclusion is verified by simulation results.