Strategies for Medium Voltage Direct Current Microgrid

This paper presents the protection strategies for a medium voltage direct current (MVDC) microgrid at a remote area mine site. The microgrid is operated to provide high power quality and reliability to sensitive loads, and also improve the energy efficiency of the mining equipment. In the MVDC microgrid, various local distributed energy resources (DERs) have been used including photovoltaic (PV) arrays, wind turbines, fuel cell stack, energy storage system and mobile diesel generators.

For the protection of transmission lines, a communication-based differential protection scheme with solid state electronic relays is employed to isolate the faulted part of the MVDC microgrid. This is further reinforced by a dc overcurrent protection as backup. Earlier research work had neglected the backup protection for dc systems. Besides, communication-based dc directional overcurrent protective relays are used for both source and load protection to support bidirectionalpower flow. MATLAB???/Simulink??? modeling and simulation results are presented and discussed to illustrate the proposed system’s dependability and security.