Impacts of superconducting fault current limiters on distance protection for grid-connected photovoltaic plants

Photovoltaic (PV) has become a crucial support for energy transformation and the development of clean energy. Superconducting fault current limiters (SFCLs), with their superconducting and quench characteristics, are considered to be effective in limiting the fault currents and enhancing the low-voltage ride-through (LVRT) capability of PV plants. However, the current-limiting impedance of SFCLs will affect the relay protection for PV plants, particularly their distance protection. In this work, investigations are carried out to explore the impacts of SFCLs on the distance protection for PV plants, revealing that SFCLs may cause maloperation of distance protection under asymmetric short-circuit faults. An improved protection method is designed to eliminate the negative impacts of SFCLs and precisely identify short-circuit faults. A model of the grid-connected PV plant with SFCLs is constructed using the PSCAD/EMTDC software package, and the simulation results validate the accuracy of the improved protection method, serving as a reference for the application of SFCLs in PV plants.