Superimposed Sequence Components for Microgrid Protection: A Review

The new challenge to protective relaying in distribution networks (DNs), due to the integration of distributed generation (DG), has become a significant area of focus and research for power engineers. To achieve high penetration of DGs in the DNs, new methods of achieving desired sensitivity, selectivity, and security of fault detection and coordination must be adopted. Recent literature shows that superimposed sequence components offer great potential in fault detection and coordination in such DNs. This paper reviews different proposed solutions to fault detection and coordination in microgrids using superimposed sequence quantities. It also includes a discussion on their application methods, unique advantages, and limitations. This way, it contributes to existing reviews on microgrid protection by presenting the unique considerations necessary for the superimposed method, as well the way conventional protection schemes can be improved for microgrid protection using this method. Results from applying a new approach for detecting faults based on superimposed negative sequence admittance is presented to demonstrate the application of superimposed quantities in fault detection.