Impact of SMES integration on the digital frequency relay operation considering high PV/wind penetration in micro-grid

This paper presents an effective solution for maintaining the frequency stability of the islanded microgrid (MG). This solution is based on the coordination of the load frequency control (LFC) using optimal proportional–integral–derivative (PID) controller-based new swarm algorithm and the superconducting magnetic energy storage (SMES) for compensating the MG frequency deviation. Due to SMES integration, the voltage and frequency will change, and the operation of the frequency relays may be affected. Therefore, the impact of the proposed coordination on the operation of the digital frequency relay (DFR) is presented. This relay will cover both over and under frequency conditions to protect the MG against high frequency variations. The proposed coordination and response of the DFR are validated using a small islanded MG in the MATLAB/SIMULINK considering high integration of renewable energy sources (RESs) and system uncertainties. The results proved the effectiveness of the proposed coordination to maintain the dynamic stability and security of the MG. In addition, the superiority of the DFR has been approved with and without using SMES.