不同负载下直流偏磁对特高压变压器各侧绕组电流影响的计算及分析

基于特高压变压器的时域场路耦合模型, 利用磁场模型中的能量扰动原理以及电路模型中动态电感参数建立瞬态电路偏微分方程模型。对特高压变压器负载时绕组电流受直流偏磁的影响进行了仿真计算, 针对阻性、感性和容性三种不同负载类型, 对绕组电流进行了直流偏磁计算, 并对其各次谐波变化进行了分析。面对特高压变压器大电感、小电阻带来的极为漫长的过渡过程以及直流偏磁计算易被淹没的难点, 通过在电路模型中增加串联电阻, 使达到稳态的时间大大缩短, 并通过电压迭代补偿, 有效消除增大串联电阻值导致的计算偏差, 通过对比所加偏置电流值与串联绕组中的直流分量值验证了本文模型的正确性。

Research on winding current of UHV transformer with different load types under DC bias

Based on the time-domain field-circuit coupling model of UHV transformer, the partial differential equation model of transient circuit is established by using the principle of energy disturbance in the magnetic field model and the dynamic inductance parameters in the circuit model.For three different load types, resistance, induction and capacitance, the influence of DC bias on winding currents and their harmonics of UHV transformer are calculated.Facing the extremely long transition process caused by large inductance and small resistance of UHV transformer and the inundation of the small DC voltage relative to the 1000 kV AC voltage during the iterative calculation, the time to steady state is greatly shortened by adding series resistance in circuit model, and the calculation error caused by series resistance value is effectively eliminated by voltage iteration compensation.The correctness of the model is verified by comparing the value of DC-bias current and the value of DC component of the series winding current.