恢复性涌流对变压器差动保护的影响

Analysis of the Effect of Recovery Inrush on Transformer Differential Protection

随着电力系统规模和容量的不断扩大,对变压器差动保护性能的要求越来越高。在建立变压器暂态数学模型的基础上,分析了变压器区外故障切除后的电磁暂态全过程,详细阐述了变压器恢复性涌流的产生机理,找出了影响恢复性涌流的主要因素。仿真结果表明,恢复性涌流中的二次谐波本身不造成差动保护的误动作,电流互感器的暂态传变误差所形成的差流才是差动保护误动的原因。因此,现场中要特别注意TA的选型。

With ever-expansion of the scale and capacity of the electric power system, there are more and tougher requirements for the transformer. Based on the mathematieal model established for transformers, this paper analyzes the entire electromagnetism transient process after a default is cut offoutside the transformer area, and it expounds the generation mechanism of the recovery inrush of the transformer and gives the main factors affecting the inrush. The simulation result shows the second harmonic of the recovery inrush doesn＇t cause the mishandling oft he differential protection. Instead, it is the differential current caused by the transient errors of the TA that causes the mishandling of the differential protection. Therefore, special attention should he paid to the type selection of the TA on the jobsite.