基于经验小波变换和高频分量的微电网保护方法

A microgrid protection method based on an empirical wavelet transform and a high frequency component

针对微电网灵活运行方式和不同于传统电源的故障特性使传统保护方法失效的问题,提出了一种基于经验小波变换和最高频分量的微电网保护方法。首先通过选取各母线的零序电流作为分析对象,然后利用经验小波变换对零序电流进行分解,选取最高频的分量作为故障特征分量。接着,求取最高频分量的一阶微分及其奇异点,并依据奇异点两边数据构建了特征方向和关联方向,通过关联方向的正负来区分故障区段和非故障区段,有效避免了微电网不同运行方式下传统保护阈值选择困难的问题。最后,大量仿真实验表明,该方法在不同接地电阻、不同故障区域、不同故障类型以及不同运行方式下均能实现准确判断。

To solve the problem that the flexible operation modes of microgrid and the fault feature different from traditional power source will make conventional protection algorithm fail,a microgrid protection method based on Empirical Wavelet Transform(EWT)and high frequency component is proposed.First,each zero-sequence current of a busbar is chosen as the analysis object,and the highest frequency component is selected as the feature component after the zero-sequence current is decomposed by EWT.Secondly,the first order differential and its singularity are calculated.These are used to obtain the feature direction and relevance direction,and the plus-minus of relevance direction is used to detect the faulty zone and healthy zone.This can effectively avoid the difficulty of selecting a threshold for the traditional protection method.Lastly,many simulation experiments prove that this proposed method can correctly detect a faulty zone in different grounding resistances,faulty zones,faulty types and operation modes.