Optimal Overcurrent Relay Coordination in Presence of Inverter-Based Wind Farms and Electrical Energy Storage Devices

This paper investigates the coordination problem of overcurrent relays (OCRs) in presence of wind power generation and electrical energy storage (EES) systems. As the injected short-circuit current of inverter-based devices connected to the electrical grid is a function of the power electronic withstand capacity, the short-circuit level would be limited for these types of devices. Furthermore, since the short-circuit current is a function of the pre-fault current, it is highly needed to take different conditions into account to accurately evaluate the injected current by such devices. This would mainly matter for the EES system operating in either charging or discharging modes, as well. This paper evaluates different operation strategies considering the variations of the load demand and the presence of large-scale wind farms as well as an EES system, while validating the suggested method for coordinating the directional OCRs (DOCRs).