基于波形正弦度特征的变压器励磁涌流判别算法

A New Approach of Transformer Inrush Detected Based on the Sine Degree Principle of Current Waveforms

提出一种基于波形正弦度判别变压器励磁涌流的方法。利用变压器励磁涌流和内部故障电流波形特征的不同,即变压器正常运行、内部短路、外部短路时波形具有正弦函数特征,而励磁涌流因其包含非周期分量、间断角,不具有正弦特征。比较波形的正弦度,形成区别涌流和短路故障的判据。通过变压器各种运行情况的大量动模试验验证了所提方法的可行性和判据的正确性。研究表明,所提方法具有特征明显,判断精确,同时对TA饱和有制动作用等特点。

A novel scheme based on the sine degree is proposed, for distinguishing between transformer magnetizing inrush current and power system fault currents. Under transformer internal and external faults, the three-phase current is mainly sinusoidal. However, the inrush current is featured by no periodic and dead angle, so it is not sinusoidal. It is possible to make use of this difference. A new method of extracting the sine degree characteristic of the waveform is presented in the paper. All the conclusions are verified by the dynamic simulation tests, the criterion proved to be feasible and accurate. Experimental results indicate that this technique is effective under different fault conditions, and it is not affected by the TA saturation.