Protection Coordination In Ac Microgrid Via Novel Voltage-Supervised Directional Over-Current Relays

Conventional Directional Over-Current Relays (DOCRs) are susceptible to dynamic changes and varying fault currents caused by various types of Distributed Generators (DGs), especially in Grid-Connected Mode (GCM) and Islanded Mode (IM), where inverter-interfaced DGs lead to low shortcircuit levels in IM. This paper presents a novel voltage measurement-based pickup setting for DOCR, where the relay operating time depends on relay’s voltage and current, ensuring optimal protection coordination for various scenarios, including GCM, IM, and during line and DG outages. The effectiveness of the proposed is demonstrated through simulations on a modified IEEE 13-bus distribution network and real-time Controller Hardware-In-Loop (CHIL) simulations using Real-Time Digital Simulator (RTDS) and dSPACE DS1104 DSP board.