直流偏磁条件下换流变压器空载特性分析

Analysis on Non-load Characteristics of Converter Transformer under DC Bias

为了深入研究直流偏磁对换流变压器运行性能的影响,基于瞬态"场-路耦合"方法,使用实际产品参数建立了二维求解模型.结合铁心材料磁导率的非线性,利用该模型分析了不同直流入侵情况下,换流变压器空载时励磁电流的波形曲线及铁心磁感应强度变化.另外,依据半波平均算法定量分析了在不同等级直流偏磁电流作用下空载损耗情况.结果显示,直流偏置水平的升高使励磁电流波形畸变;低次谐波逐渐增加;铁心磁密峰值呈非线性增长并趋于饱和.同时,空载损耗也随之增加.该方法为考虑换流变压器偏磁时的设计和维护提供了有效手段.

Based on the transient ＂field-circuit coupled＂ method,two-dimensional solution mode is established according to the parameters of the actual product,so that people can further research the effect on the operating performance of converter transformer caused by DC bias better.Considering the nonlinearity of core material＇ s permeability,the model is used to analyze the exciting current waveform curves and the iron core magnetic flux intensity changes of no-load in different DC bias conditions.In addition,the condition of no-load loss is analyzed quantificationally in accordance with half-wave average algorithm.The results show that the increase of DC bias ratio leads to distortion of the exciting current waveform.The low harmonics become more and more abundant.The peak value of iron core magnetic flux intensity grows nonlinearly and tends to be saturated.Synchronously the no-load loss is also increased.This method provides an effective means for the design and maintenance of converter transformer＇ s DC bias.