用相关函数原理识别变压器励磁涌流和短路电流的新方法

变压器采用纵联差动保护时，如何正确识别励磁涌流和内部故障时的短路电流是关键问题。文章将变压器励磁涌流和各种内部故障电流均看作随机信号，应用数字信号处理中的相关函数原理对采样数据进行分析，计算采样数据的自相关函数，并与正弦电流形成的标准自相关函数进行相似比较运算，利用相似系数大小区分短路电流和励磁涌流。理论分析和动模试验结果验证了该方案的可行性。

A NEW METHOD TO IDENTIFY INRUSH CURRENT AND SHORT CIRCUIT CURRENT OF TRANSFORMER BASED ON CORRELATION FUNCTION

When longitudinal differential protection is applied to transformer protection, how to identify the inrush current and short circuit current caused by internal fault is the key problem. Here, regarding the inrush current and short circuit current as the random signal, the sampled data are analyzed by correlation function principle in the digital signal processing and the self-correlation function of the sampled data is calculated. Through the similar comparison operation conducted by standard self-correlation function formed with sinusoidal current the short circuit current and the inrush current can be distinguished by the magnitude of similarity coefficient. The results of theoretical analysis and dynamic simulation verify the feasibility of the proposed method.