A multi-agent solution to multi-thread protection of DG-dominated distribution networks

Abstract

Integration of Distributed Generations (DGs) into Distribution Networks (DNs) has alarmingly altered the level of short circuit current, leading to some critical protection challenges. Given that proper operation of overcurrent relays depends on location, type, or generation capacity of DGs, this paper proposes an agent-based algorithm guaranteeing the protection validity, regardless of DGs’ dependencies. First, sharing their information with the main grid agent, relay agents are categorized into different zones to determine in advance the operating status of a protection system. Next, according to the network condition, the fault clearing process is divided into two parts: independent operation and operation in accordance with the relay's conditions. Last, the protection system settings are updated following the fault clearing process. Furthermore, a multi-thread processing scheme is presented to improvethe intrinsic slowness of agent-based techniques, preventing any probable malfunction during fault conditions. Accordingly, the protection structure is divided into three levels (threads) running simultaneously: relay operation status detection, fault clearing, and updating protection settings. The simulation results are in good agreement with the proposed protection scheme.