快速识别转换性故障的变压器差动保护新判据

电流互感器饱和是影响变压器差动保护可靠性的重要因素之一.传统的带比率制动特性的变压器差动保护在一定程度上提高了防止区外故障时保护误动的能力,但是如何及时处理区外转区内故障时保护的快速开放成为新的问题.文中提出一种简单的解除闭锁的方法,具体做法是,在选定的计算区域,利用变压器两侧电流综合负序分量的最大值与差动电流的综合负序分量进行比较,不仅能准确识别区内、区外故障,而且对于转换性故障也具有较好的识别能力.ATP仿真实验验证了该方法的有效性.

A New Criterion for Transformer Differential Protection to Rapidly Identify Transferring Faults

Current transformer saturation has always been one of the major problems of degraded reliability of the transformer differential protection.The ratio restraining differential characteristic can enable the transformer protection to be immune to the mal-operation in the external fault to some extent.But how to unblock the differential protection rapidly for the transferring fault from an external one to an internal one has become a new problem.This paper presents a new method of unblocking the differential protection for the transferring fault.In the method proposed,current comparison is made between the maximal value of the integrated negative phase sequence component of the current on the two sides of a transformer and the integrated negative phase sequence component of the differential current.Based on the current comparison results,the method proposed can not only accurately identify the internal fault and the external one,but also the transferring fault developed from the external fault to the internal one.Simulation results of ATP validate the effectiveness of the method proposed.