Optimal Power Distribution Method for Wind Farms to Enhance the FRT Capability of the LCC-HVDC System Under Commutation Failure

Line-commutated converter (LCC) based high-voltage direct current (HVDC) technology is a common technology for long-distance transmission of electricity. Commutation failure is a common fault in the LCC-HVDC transmission system, which brings new challenge to the stable operation of wind turbines on the sending AC grid. It is necessary to suppress the overvoltage of the sending AC grid to improve the fault ride-through (FRT) capability of the LCC-HVDC system under commutation failure. The voltage amplitude of the sending AC grid is affected by the power characteristics of the wind farms on the sending AC grid. Based on the analysis of the mathematical relationship between the reactive power of the wind farms and the overvoltage of sending AC grid and the mathematical relationship between the reactive power absorption capacity of the wind farms and the active power of the wind farms, the overvoltage of the sending AC grid can be suppressed by redistributing the power of the wind farms. An optimized power distribution method for wind farms is proposed to suppress the overvoltage of the sending AC grid and improve the FRT capability of the LCC-HVDC system under commutation failure. The effectiveness of the proposed optimal method is verified through two cases by building the simulation model based on Matlab/Simulink.