Impact of distributed generator controllers on the coordination of overcurrent relays in microgrid.

In the presence of distributed generators (DGs) the fault current sensed by relay in the forward direction is larger than that in the reverse direction. Thus, it is required to have different relay settings for both forward and reverse directions. This paper investigates the impact of DG controller operating modes on the coordination of conventional and dual setting overcurrent relays (OCRs). The different DG control modes are voltage control mode (VCM) and current control mode (CCM). A comparative study of protection coordination is presented in both the operating modes of the DG. This scheme is tested on a 3-bus meshed system and the IEEE 34-node distribution system in which an electronically interfaced DG is connected. The protection coordination problem is formulated as a nonlinear programming problem and the optimal settings of OCRs are determined by using a genetic algorithm. [ABSTRACT FROM AUTHOR]