Development of a short circuit strategy for medium voltage hybrid microgrids

This paper evaluates the behavior of a medium voltage hybrid microgrid in case of a fault, and a short circuit strategy is developed for the power electronics based distributed generators. Without any means of communication, an autonomous control concept for both grid feeding and grid forming inverters is realized. The suitability of reactive current injection strategy for medium voltage microgrids is evaluated and also the frequency response of rotational and non-rotational grid forming units is investigated. The developed strategy and its effectivity are verified through real time simulation test scenarios. The case studies investigated in this work identify worst case scenarios concerning voltage and frequency stability, as well as provision of sufficient overcurrent for the traditional protection means identifying the fault location.