Study of Reactive Power Clamp Control for Commutation Failure in Hybrid LCC-VSC HVDC System

Abstract

The receiving-end hybrid LCC-VSC system is a new type of hybrid DC transmission system. In order to give full play to the resistance of the voltage source converter high voltage direct current transmission to commutation failure, a reactive power control strategy based on hybrid HVDC system is proposed. First, the mechanism of commutation failure and the coupling characteristics of VSC and LCC in the receiving end hybrid system are analyzed. By judging the severity of the fault, the VSC reactive power control method is changed or the VSC-HVDC inverter side constant reactive power controller is adjusted. The setting value ensures that the VSC active power is transmitted while maximizing the reactive power, and quickly improves the reactive power support capability of the VSC-HVDC to the receiving end AC system; the receiving end hybrid LCC-VSC model is built in PSCAD/EMTDC Simulation analysis and verification by commutation failure immunity factor and commutation failure probability index prove that the proposed control strategy is beneficial to improve commutation failure.