Coordinated Control of SFCL and SMES for Transient Performance Improvement of Microgrid With Multiple DG Units

Aiming at a microgrid system with multiple distributed generation (DG) units, this paper proposes the coordinated control of a flux-coupling-type superconducting fault current limiter (SFCL) and superconducting magnetic energy storage (SMES), so as to improve its transient performance under fault conditions. On the one hand, using the SFCL and the SMES enhances the microgrid's fault ride-through capability. And for some specific faults, the microgrid should disconnect from the main network, and the coordinated control of the SFCL and the SMES makes the microgrid carry out a smooth transition between its grid-connected and islanded modes. Relevant theory analysis of structure principle, control strategy, and capacity design is conducted, and simulations under different fault conditions are performed in MATLAB. From the results, the coordinated control of the SFCL and the SMES can contribute to limit the fault current, improve the voltage at the point of common coupling (PCC), and alleviate the frequency/reactive power fluctuations. Thus, the microgrid's robustness against short-circuit faults can be well increased.