基于时差法的Y/△接线变压器和应涌流鉴别新方法

近年来，出现了多起和应涌流引起变压器差动保护误动的事件，但目前还没有有效的方法对和应涌流进行识别。该文以常见的2台Y/△接线方式变压器并联情况为主，根据变压器产生和应涌流一侧的线电流突变与差流出现时刻有一定时差的特点，提出利用时差法鉴别和应涌流并闭锁差动保护的方案。在TA饱和情况下，可利用数学形态学方法对小时差情况进行判定。将另一侧线电流的变化情况作为辅助判据后，该方法能正确区分变压器和应涌流及和应涌流产生过程中发生内、外部故障的情况。Matlab/Simulink仿真实验验证了该方法的可行性和有效性。

A New Algorithm Based on Time Differential Method to Identify Sympathetic Inrush of Transformers Connected in Wye-delta Mode

In recent years, several cases of mal-operation of transformer differential protection due to sympathetic inrush appeared, but the problem how to distinguish the sympathetic inrush has not been resolved yet. Based on the synchronization measurement of the change of line current and differential current, an algorithm of distinguishing the sympathetic inrush and blocking the differential protection was put forward, which is applicable to two paralleled wye-delta connected transformers. Under the condition that the current transformer saturated, a method based on the mathematical morphology to identify the synchronization of the change of line current and differential current was proposed. Adopting the abrupt change of line current in the other side as auxiliary criterion, this algorithm could distinguish the sympathetic inrush, and internal, external fault during sympathetic inrush occurring. Simulation results validate its feasibility and reliability.