Microgrid Protection: Technical challenges and existing techniques

Abstract

The design of protection systems associated with medium and low voltage networks has traditionally been based on the assumption of unidirectional power flows, making the use of time coordinated overcurrent relays an efficient and reliable way of protecting against network faults. The changes that these systems have undergone over the recent decades regarding distributed generation, along with the fact that many of these sources can be connected to form independent microgrids, have challenged this perspective. A number of alternative solutions have recently appeared in technical literature. Therefore, this paper aims to provide a comprehensive overview of the existing proposals for protection design in microgrids. Apart from describing the most relevant options presented to date and classifying them in specific groups, a comparative analysis is performed in which the most important benefits and drawbacks of each approach are presented. Finally, some conclusions and practical recommendations are derived from the analyzed references.