A Multi-Agent System for protection coordination of radial systems in the presence of distributed generation

This paper proposes a Multi-agent System (MAS) approach to coordinate overcurrent relays, aiming to protect distribution systems with distributed generators. The connection of distributed generation (DG) units causes a reduction in the efficacy of protection systems coordination and, in some cases, an increase of operating times. Coordination studies aim to guarantee the protection selectivity in a diversity of fault situations, also considering topological changes. Consequently, sometimes a correct protection operation at every point of the system in every possible situation cannot be guaranteed. The proposed MAS uses communication between agents to achieve on-line coordination. In order to evaluate the approach, simulation tests of a real system were executed and the protection operating times using the proposed methodology are compared with the operating time of existing relays. Results show that this approach provides a noticeable reduction of protection operating time and there is also an improvement of selectivity.