换流变压器差动保护对称性涌流识别算法研究

Research on Identification of Symmetrical Inrush Current Algorithm for Converter Transformer Differential Protection

本文比较了换流变和普通变压器在接线形式上的特殊性,分析了换流变保护差动中对称性涌流产生的原因。根据换流变对称性涌流的波形特征,提出了一种虚拟制动电流的构建方法,通过构建的虚拟制动电流和实际采样电流进行波形预测,根据定义的波形系数函数进而求取波形系数,通过波形系数的差异可以有效识别对称性涌流。通过仿真验证,所提出的对称性涌流识别算法可以有效避免换流变保护装置在发生对称性涌流时产生误动,发生空充于故障的情况时保护可以有效动作。

In this paper, the particularity of converter transformer and common transformer in connection form was compared, and the cause of symmetrical inrush in differential protection of converter protection was analyzed. According to the waveform characteristics of symmetrical inrush current, a virtual restraint current construction method was proposed, virtual restraint current and actual sampling curren was used for waveform prediction, waveform coefficient was obtained according to the defined waveform function. Then the symmetrical inrush can be identified effectively by the difference of the waveform coefficient. The simulation results show that the proposed algorithm can avoid misoperation of protection device when the symmetric inrush occurs, and it can act effectively when no-load switching into fault.