Study of Resistive Superconducting Fault Current Limiters for Stability Improvement of VSG-Controlled Multiple Microgrid Clusters

Multiple microgrid (multi-MG) clusters based on virtual synchronous generator (VSG) control can preferably incorporate renewable energies. Nevertheless, the power angle stability (PAS) of VSG-controlled multi-MG clusters is easy to be influenced by grid faults. In this paper, resistive superconducting fault current limiters (R-SFCLs) are introduced to deal with this PAS problem. It is designed to install the R-SFCLs at the point of common coupling (PCC) of each MG in the clusters. The transient stability mechanism based on power balance and swing equation is analyzed to clarify the impacts of the R-SFCLs. Through MATLAB, a simulation model of three VSG-controlled MGs with R-SFCLs is built, and different fault scenarios are imitated for checking the performance behaviors of the R-SFCLs. From the simulation results, the R-SFCLs can visibly suppress the overcurrent inrush and assist the MGs in the clusters to fulfill the fault-ride through (FRT). Moreover, the energy dissipation of the R-SFCLs is calculated, and an improved power balance property is obtained in the multi-MG clusters to alleviate the power-angle fluctuations. Consequently, the effectiveness of the R-SFCLs on reducing the relative power angle variation is demonstrated, and the transient stability of the multi-MG clusters withstanding the three-phase faults is favorably enhanced.