Multi-Agent Approach to Wide-Area Integrated Adaptive Protection System of Microgrid for Pre-and Post-Contingency Conditions

This paper reports on development of communication-based integrated adaptive protection scheme for distribution systems with penetration of Distributed Generators (DGs). In the proposed system, during pre-contingency conditions (permanent fault occurrence), every protection relay has sufficient intelligence to autonomously adapt its settings so that becomes coordinated with other relays after any change in operation mode or DGs connection status. But if a permanent fault occurs in the network, protection system will face with various reconfigurations (islanded parts) because of faulty section clearance. In the proposed scheme, in order to expanding the adaptive protection strategy to post-contingency period, the decentralized adaptive protection (by relays) for pre-contingency period (prior to fault occurrence) is integrated with MicroGrid Central Controller (MGCC) which adapts protection settings during post-contingency conditions. Therefore, the protection system becomes ready for detection of possible subsequent faults after the first permanent fault. In this paper to ensure reliability and fast operation of the protection scheme, the proposed protection system is based on Multi-Agent System (MAS). Different parts of microgrid like MGCC, relays, DGs, PCC (circuit breaker at the beginning of microgrid) are considered as agents by decision making, logical (I/O) interface and communication abilities.