基于不同区域平均等效瞬时电感比值的励磁涌流鉴别方法

利用变压器瞬时励磁电感能够反映其饱和程度的特点,提出了一种由差流大小划分变压器的非饱和区域与饱和区域,根据两个区域内平均等效瞬时电感比值的大小识别励磁涌流和短路故障的方法.在涌流发生的过程中,变压器不断经历非饱和状态与饱和状态,相应等效瞬时电感由大变小,变化剧烈,一个周期内非饱和区域与饱和区域内平均等效瞬时电感的比值很大.而发生短路故障时,等效瞬时电感很小,而且基本不变化,按差流划分的非饱和区域与饱和区域内平均等效瞬时电感的比值约为1.该方法原理简单,整定容易,识别速度快,试验结果验证了其正确性和有效性.

Improved Method Based on the Ratio of Average Equivalent Instantaneous Inductance in Different Zones to Identify Excitation Inrush

In terms of the characteristic of the instantaneous excitation inductance reflecting the saturation stage in a power transformer, an improved method is proposed to distinguish between the excitation inrush and the short-circuit fault based on the ratio of average equivalent instantaneous inductance (AEII) between the non-saturation and the saturation zones, which are divided according to a threshold of differential current. During the inrush, the value of equivalent instantaneous inductance varies severely from small to large as the transformer entering into the saturation and withdrawing from it, hence the ratio of AEII between the non-saturation and the saturation one is very large in one cycle. However, for the short-circuit fault in the transformer, the value of the equivalent instantaneous inductance is very small, and changes little. Hence the ratio is approximately equal to one. The principle and setting of this method is simple and easy, and its distinguishing time is short. Experimental results verify that the method is correct and effective.