Assessing the impact of distributed energy resources on overcurrent protection in microgrids for enhanced effectiveness

Abstract

The inevitable diminutions of fossil fuel, declined energy efficiency, and sustainability considerations have sparked concerns about centralized generating facilities in traditional grids. Therefore, integrating distributed energy resources (DERs) into system installations has emerged as a dependable option to meet growing energy requirements while maintaining acceptable quality and efficiency standards. Despite notable advancements in system characteristics post-DER integration, this decentralized layout has impacted the functioning patterns of the entire system, including protection schemes. Designing an effective protection strategy in DER-rich systems is challenging due to many hurdles, including variations in short-circuit values, sympathetic tripping, protection blindness, loss of coordination, and system instability post-faults. Thus, this paper evaluates the efficacy of overcurrent protection in addressing the challenges introduced by DERs in power grids. It investigates over- current relay coordination issues, clarifying relevant equations and formulations from literature. Moreover, it assesses overcurrent relay performance in various scenarios post-DER integration. This evaluation is performed on a modified IEEE 33-bus system, equipped with DERs. Simulation and analysis are conducted using DigSILENT and MATLAB to simulate the system, analyze network stability, and solve optimization problems.