The Influence of VDCOL Parameters on the Recovery Characteristic after Commutation Failures of HVDC Links Fed into Weak AC Systems

The faults occurred in the receiving terminal AC system of an HVDC transmission link may cause commutation failures of the inverters. When the receiving AC system is weak, the AC/DC system may be difficult to restore to a stable operation state due to continuous commutation failures even after faults clearance. Optimizing HVDC controls for the weak receiving AC system condition is an effective method to improve the recovery performance. This research focuses on the optimization of VDCOL control parameters for improving fault recovery performance of HVDC links with weak receiving terminal AC systems. Based on the original VDCOL control parameters that was obtained from an earlier HVDC project, the optimized control parameters was proposed for the studied HVDC project with weak AC system at the receiving terminal. Comparative simulation studies were conducted using the two sets of VDCOL control parameters respectively. Simulation results show that some improvement of the fault recovery performance can be achieved by the optimization of VDCOL parameters alone.