励磁涌流引起的变压器差动保护误动作分析及对策

励磁涌流和内部故障的可靠鉴别是实现变压器差动保护的关键问题，它直接制约着变压器差动保护正确动作率。介绍了一起励磁涌流引起的变压器差动保护误动作行为。对变压器差动保护的配置、故障录波数据和保护动作行为进行了分析，结合二次谐波制动原理和间断角制动原理对故障录波数据中变压器励磁涌流的谐波数据和波形进行了详细分析，提出了对励磁涌流相关整定值进行改进的防范对策。分析方法及过程具有一定的参考价值。

An Analysis and Corresponding Countermeasures for Transformer Differential Protection Misoperations Caused by Magnetic Inrush Current

A new algorithm based on two points product method is presented in the paper to address the mal-operation in the transformer differential protection due to magnetizing inrush current. This method is based on the principle that the waveform of the inrush is distorted seriously, while the fault current keeps nearly sinusoid. By the trigonometric function algorithm, the method samples currents with the differential filter continuously, and obtains square sums of two neighboring PI/2 currents for many groups, and then distinguishes the inrush current by the ratios of square sums of neighboring groups. Theoretical analysis and dynamic simulation results demonstrate the effectiveness, reliability, and user-friendliness of the method under various fault conditions.