高压内置型变压器空投导致零序电流保护误动分析及对策

Analysis and measures of zero sequence current protection malfunction caused by no-load high-voltage built-in transformer

对高压内置型变压器励磁涌流及其零序分量特性进行深入分析。结合该类型变压器结构特点,指出与常规变压器相比,高压内置型变压器涌流零序分量更大且衰减更为缓慢,造成相关零序电流保护更容易发生误动。在PSCAD/EMTDC中搭建仿真模型,分析了合闸角、剩磁和运行方式对高压内置型变压器空投时的励磁涌流零序分量的影响,并给出了零序电流保护误动概率。建议通过优化零序电流保护定值、增加空载合闸运行及间隔时间、采用涌流抑制措施来保证变压器正常投运。

The characteristics of excitation inrush current and its zero sequence component of high voltage built in transformer are studied and analyzed in this paper.Compared with the conventional transformer,the high-voltage built-in transformer inrush current zero sequence component is larger and decays more slowly under its structural characteristics,because the zero sequence current protection are more prone to misoperation.Based on EMTDC/PSCAD,the effect of residual magnetism,closing angle and operation mode on the zero sequence component of no-load transformer is analyzed.Besides,the misoperation probability of zero sequence current protection is given.It is recommended to ensure the normal operation of the transformer by optimizing the zero sequence current protection setting value,increasing no-load closing operation and interval time,and adopting inrush current suppression measures.