单相变压器直流偏磁励磁电流仿真分析

Simulating Analysis of Exciting Current of Single Phase Transformer on DC Bias

通过铁心的非线性磁化曲线JilesAtherton理论,在MATLAB软件环境里建立了变压器铁心的仿真模型并利用该模型分析了直流偏磁大型单相变压器开路时励磁电流的波形特征。结果表明,随流入变压器的直流电流I0增加,励磁电流畸变愈重,并在I0增大到一定程度后严重半周饱和,其谐波分量越来越大且出现I0增加快速增长的偶次(主要是2次)谐波。

Based on jiles-Atherton theory on ferromagnetic hysteresis, model of nonlinear magnetization characteristics for saturate transformer is set up. Programmed using MATLAB, exciting current of transformer under DC bias is computed and simulated in time domain under short circuit and no-load condition. Synchronously harmonics content of excited current is analyzed in frequency domain. The result shows that the degree of DC bias for core and the flux density increase when DC increases, the waveform of exciting current became much more distort. When the DC increases enough, the exciting current inclines to half-circle saturation. The harmonics content become more and more abundant. The first and third order harmonic increase steadily with increases of DC. Especially the second order harmonic increases rapidly with increases of DC. A few of fourth order harmonic arises.