The Improved Transient Overvoltage Suppression Strategy of Large-Scale Renewable Energy HVDC Transmission System

When an AC fault occurs at the receiving end of a large-scale renewable energy high voltage direct current (LREHVDC) transmission system, which leads to commutation failure (CF). Many suppression strategies address this issue by adjusting the voltage dependent current order limiter (VDCOL) control parameters. However, improper parameter adjustments can easily cause overvoltage. To effectively mitigate the overvoltage caused by such methods, this study proposes an improved transit overvoltage suppression strategy (ITOSS) based on dynamic reactive power control, by regulating the reactive power output of the grid-connected inverter for renewable energy generation, which actively absorbs the surplus reactive power injected back into the power grid by the reactive power compensation device (RPCD) of the LCC-HVDC rectifier station, thereby suppressing overvoltage at the sending end. Finally, a detailed model is developed on the PSCAD/EMTDC simulation platform. Simulations are performed under various control scenarios and systematically analyzed to validate the effectiveness of the proposed strategy rigorously.