Study on fault characteristics and distance protection applicability of VSC-HVDC connected offshore wind power plants

When a fault occurs in the power grid, voltage-source converter high-voltage direct current (VSC-HVDC) connected offshore wind power plants (OWPP) will enter the fault ride-through operation state under the control of wind turbines and modular multilevel converters. The adverse effects of its complex fault current characteristics on power grid protection are highlighted. According to the topological structure and control strategies of OWPP, a theoretical calculation method for OWPP’s fault current under symmetric and asymmetric faults is proposed. On this basis, this paper comprehensively studies the applicability of distance protection on the tie line of OWPP, analyzes the existing problems, and gives corresponding engineering solutions. The correctness of the analysis conclusions is verified by digital simulation results.