带平衡绕组的分裂式变压器短路电流计算分析

Calculation and Analysis of Short-circuit Current of Split-winding Transformer with Stabilizing Winding

分析短路等值电路并计算故障电流最大值是带平衡绕组的分裂式变压器设计的关键问题之一。应用对称分量法和基于场路耦合的有限元分析法,对突然发生不同短路故障情况(包括单相接地短路、两相接地短路、两相相间短路和三相短路)下的变压器进行了等值电路分析和短路电流计算。以型号为SFFZ10-88 000 kV·A/220 kV的变压器为例进行了解析计算和仿真分析。结果表明:单相接地短路和两相接地短路时的短路电流较大;在两相接地短路时的安匝平衡是关于矢量平衡,此时有限元分析法更适用。

The analysis of short-circuit equivalent circuit together with the calculation of the maximum value of fault current is one of the key issues for the design of a split-winding transformer with stabilizing winding.In this paper,by using symmetrical component method and finite element analysis method based on field-circuit coupling,the equivalent circuit is analyzed and the short-circuit current is calculated when the transformer is under sudden short-circuit fault,e.g.,single-phase earth fault,two-phase earth fault,two-phase interphase fault,and three-phase fault.A transformer of type SFFZ10-88 000 kV·A/220 kV is taken as an example,based on which the analytical calculation and simulation analysis are performed.Results show that the short-circuit current is larger under single-and two-phase earth fault;the ampere-turns equilibrium under two-phase earth fault is related to a vector equilibrium,where the finite element analysis method is more applicable.