合空变涌流谐波对直流系统换相失败的影响及分析方法

Influence and Analysis Method of Harmonics of Transformer Energizing on Commutation Failure of DC System

变压器空载合闸会产生含有大量谐波成分的励磁涌流,多重谐波综合作用会对直流系统造成影响,引发换相失败。为此,首先通过谐波换相系数分析得出直流系统换相失败原因为多重谐波中低次谐波的影响;其次通过基波电压幅值变化与过零点位移两个方面定义谐波综合影响因数,评价多重谐波对直流系统换相过程的影响程度;再以实际宜华±500kV直流输电系统仿真模型,结合1 000kV主变模型进行仿真计算,计算谐波综合影响因素。研究结果验证了仿真过程中7次换相失败的发生。

The magnetizing inrush current of a transformer with a large number of harmonic components will be generated during the no-load closing of the transformer.The combined effects of the multiple harmonics will affect the DC system and cause commutation failure.In this paper,firstly,the harmonic commutation coefficient analysis shows that the commutation failure of the DC system is mainly caused by the influence of the low-order harmonics in the multiple harmonics.Secondly,harmonic comprehensive influencing factor was defined by the fundamental voltage＇s change of the amplitude and zero displacement,and the impact of multiple harmonics on DC system commutation process was evaluated.Based on the actual simulation model of Yihua ± 500 kV DC transmission system and the 1 000 kV main transformer model,the harmonic comprehensive influencing factor was calculated.The results verify the occurrence of seven commutation failures in simulation.