Optimal Protection Coordination of Dual-Setting Digital Directional Over-Current Relays with Renewable Resources and Energy Storage System

In this paper, the protection coordination for Digital dual-setting directional overcurrent relays (DS-DOCR) in the presence of renewable energy sources and energy storage system in the conditions of maximum and minimum fault current in the distribution network is investigated. The proposed scheme minimizes the total operating time of the relays to achieve fast protection coordination in DS-DOCR relays. In addition, to increase the flexibility in the DS-DOCR settings, the permitted range for all relay parameters such as A, B, pickup current (IP), and time dial setting (TDS) is explained in both forward and backward directions. In the proposed scheme, the operating results of DS-DOCR relays on the IEEE 9-bus distribution network in the presence of maximum penetration of photovoltaic sources (PV), wind and energy storage systems (ESSs), in maximum and minimum fault current conditions are investigated. Simulation of the study method is done in DIgSILENT Power Factory software. The numerical results indicate that the proposed solution algorithm has ideally provided the optimal values ​​of the DS-DOCR relays setting parameters, and is capable of achieving reliable and fast protection coordination.