In order to improve the performance of failure recovery characteristic of the HVDC,a novel VDCOL control method named piecewise-variable-rate VDCOL is proposed based on the study of VDCOL’s influence on the HVDC system’s reactive power consumption and voltage stability,which divides the voltage drop or recovery process into several different stages which have different power recovery rate according to the voltage recovery level.The formula for calculating the initial value of the controller is derived；the strategy using Simplex algorithm to optimize the controller parameters is designed, and analyzed on the number of segments effect on performance and methods to determine it. The control effect is compared between the PVR-VDCOL and the linear VDCOL, and the control effect under different number of segments was compared. The simulation results in PSCAD/EMTDC showed that the proposed PVR-VDCOL control method can effectively improve the failure recovery performance of the HVDC system.
