Abstract
The fluctuated nature represents the main obstacle for increasing the penetration level of photovoltaic (PV) generators in utility microgrids. The energy storage systems (ESSs) represent the main solutions to get over these fluctuations. Among various ESSs, the superconducting magnetic energy storage (SMES) systems have proven themselves as an effective solution. The SMES control systems in the literature result in a shortened lifetime, degraded thermal behavior, and high AC losses in the SMES. Thence, reliable operation of SMES systems and microgrids has been given wide concerns due to the large fluctuations in microgrids with high levels of PV penetrations. This paper presents a SMES-based fuzzy logic approach for improving the reliability of SMES and utility microgrids with high PV penetration levels. The proposed SMES controller employs the state of charge (SOC) of SMES as an input. This, in turn, can effectively extend the lifetime of SMES due to eliminating the overcharge and deep discharge operating states. Moreover, the proposed system controls smoothly the SMES current using the fuzzy rules' system. The superiority and effectiveness of the proposed SMES controller are verified using simulation-based case studies of utility grids with high PV penetration levels. The obtained results show the effective smoothing of fluctuated power and constant bus voltages in the studied microgrid under the proposed controller. In addition, the proposed SMES controller provides superior performance regarding the lifetime and reliability of the SMES systems and microgrid components.