An MVDC microgrid for a remote area mine site: Protection, operation and control

This paper investigates the design of a medium voltage direct current (MVDC) microgrid for a remote area mine site. The various aspects covered include its protection schemes as well as operation and control. This is intended to provide a voltage of high power quality and reliability at the sensitive load terminals, and also improve the energy efficiency of all the mining equipment. In the proposed MVDC microgrid, several local distributed energy resources (DERs) have been employed including PV arrays, wind turbines, a fuel cell stack, an energy storage system and mobile diesel generators. A comprehensive analysis is presented on the protection, operation and control of the MVDC microgrid system. A communication based differential protection scheme with solid state electronic relays is employed for isolating only the faulted portion of the MVDC microgrid. Previous research work had largely neglected the backup protection for DC systems. In this paper, the overcurrent protection device is utilized for backup protection. Furthermore, with an appropriate communication and cooperative framework among these DERs accompanied by dc bus signaling (DBS) control, the dc bus voltage can be maintained within an acceptable range. MATLAB/Simulink modeling and simulation results are presented and discussed to illustrate the system's reliability, security and power quality.