变压器涌流对零序电流保护的影响分析

Influence of transformer inrush on zero -sequence current protection

采用ATP仿真计算与实际分析相结合的方法,分析了单台变压器励磁涌流最大零序分量,以及多台变压器涌流零序分量与主变中性点接地方式的关系,得出:剩磁越大,通过调整合闸角所能取得的涌流零序分量越大,当实际最大剩磁为0.7Bm时,涌流零序分量最大可到0.95IN;多台变压器涌流零序分量与中性点接地变压器台数成正比。结合220kV零序电流保护整定原则,分析了涌流零序分量对220kV零序电流保护的影响,得出它对主变零序电流保护和线路零序电流Ⅰ、Ⅱ、Ⅳ段没有影响,对线路零序电流Ⅲ段和母联保护有不利影响,并提出了运行和整定时需采取的相应措施。

With ATP simulative calculation and practical analysis,the maximum zero- sequence inrush current of single transformer,as well as the relationship between the zero- sequence inrush current of multiple transformers and the neutral point grounding mode of main transformer,is analyzed. The conclusions are that,the more the residual flux is,the greater the zero-sequence inrush current obtained by switching angle adjustment will be：when the actual maximum residual flux is 0.7Bm,the maximum zero-sequence inrush current will be 0.95 IN;the zero-sequence inrush current of multiple transformers is proportional to the number of neutral point grounded transformers. Combined with the setting principle of 220 kV zero-sequence current protection,the influence of zero -sequence inrush current on it is analyzed. The zero-sequence inrush current has no influence on zero-sequence current protection of main transformer and on Zone 1,2 and 4 of line zero-sequence current protection,but has bad influence on Zone 3 of line zero-sequence current protection and bus -link protection. The corresponding measures are put forward for their operation and setting.