Microgrid Protection with Penetration of DERs - A Comprehensive Review

Distributed Energy Resources (DER) early uses as a backup generation has been progressing toward permanent Distributed Generation (DG), along with the development and enhancement of new technologies over small-scale generation. Over last few years, increasing penetration of renewables in the distribution networks at consumer level raises concerns on protection, control, stability and reliability. Considering the DG integration and wide variations in operating conditions of the microgrid, relays experience protection issues at fault current level violating important tripping decision rules. This study reviews the impact of DG penetration as integration means on traditional overcurrent (OC) protection schemes, being the most common and widely used relaying scheme in radial distribution networks. This paper reviews the most representative methods with respect to various challenges uncovered by exhaustive studies and validations and reported in the literature. Further, potential adaptive and intelligent schemes are also discussed for enhancing the performance over traditional protection schemes in microgrids.