Progress and problems in micro-grid protection schemes

Globally, gradual depletion of fossil fuel resources, poor energy efficiency and environmental pollution are among the main problems faced in the conventional power system. This leads to a new trend of generating power locally by using Distributed Energy Resources (DERs) at distribution voltage level. The concept of micro-grid has appeared as an attractive alternative for integration of DERs in the distribution networks which has numerous advantages in terms of reliability and power quality. Despite the advantages, several challenges are still hindering the development of micro-grids. One of the challenges is micro-grid protection, and to resolve this, researchers have been working to develop different protection schemes. The objective of this study is to review previous research works on the existing protection strategies deployed in addressing micro-grid protection issues in both grid-connected and islanded mode of operation.