Transient Overvoltage Analysis of Wind Farm PCC Caused by HVDC Commutation Failure under Different Faults

Commutation failure is one of the most common events in line-commutated converter high voltage direct current (LCC-HVDC) transmission systems. During the commutation failure period, an transient overvoltage will be generated in the sending AC system, posing a serious threat to the stable operation of the new energy power grid. Aiming at this problem, this paper uses the PSCAD platform to establish an electromagnetic model of the power system including DC transmission lines and doublyfed wind turbines. Under the same fault location, by applying three-phase fault and single-phase fault at different times, the transient overvoltage peak value at the wind turbine port during the commutation failure period is compared. The simulation results found that the peak value of transient overvoltage is related to the moment of fault occurrence, and when a fault occurs at some point in a system cycle, the transient overvoltage peak caused by the single-phase fault is more serious than that caused by the three-phase fault. According to the analysis of the simulation results, this phenomenon has a great relationship with the transient reactive power characteristics of the rectifier during commutation failure.