Active Power Criterion Based High-Adaptive Differential Protection for Power Electronic Equipment

In flexible AC/DC microgrids, a variety of non-traditional power equipment are in operation, such as AC/DC interlinking converters. Moreover, due to the influence of interlinking converters, short-circuit fault characteristics in microgrids are much different from those in traditional distribution networks, which makes existing protection methods have poor adaptability. This paper introduces an active power variable-based differential protection method, which is suitable for various non-traditional power equipment. While in normal operation or during an external fault state, internal active power losses are rather minimum, resulting in nearly zero power difference between equipment terminals. However, during an internal fault state, the active power difference between terminals becomes extremely large, which can be adopted as protection criteria. The selectivity and rapidity are verified by simulation cases, and the aforementioned method is applicable to various non-traditional equipment, such as single-phase AC/DC converters, three-phase AC/DC converters, etc.