A Predictive Control Method for Suppressing the Continuous Commutation Failure of LCC-Based HVDC Systems

摘要

Unreasonable selection of control parameters of voltage dependent current order limiter (VDCOL) in the DC system may lead to further deterioration in recovery characteristics, causing continuous commutation failure. Firstly, by analyzing the relationship between VDCOL recovery slope, the AC bus voltage and the extinction angle, a method for changing the slope of VDCOL characteristic curve according to the AC bus voltage during faults is proposed. When the commutation failure occurs at DC grid, the VDCOL immediately sets the characteristic curve slope during system recovery according to the real-time measured commutation voltage and critical extinction angle value. This method can reduce the reactive power consumed by the converter which benefits to suppress the continuous commutation failure of the DC system to a certain extent. Finally, the CIGRE HVDC standard test model is built in PSCAD/EMTDC. and the effectiveness of the proposed recover) strategy in suppressing subsequent commutation failure and improving system recovery characteristics is verified. This method makes full use of HVDC system controller and does a great significance to improve the recovery performance of HVDC.