Research on Commutation Failure Suppression Strategy for Receiving-End Hybrid LCC-VSC Based on Reactive Power Clamp Control

Commutation failure is one of the common faults in line commutated converter based high voltage direct current (LCC-HVDC). In the receiving-end hybrid LCC-voltage source converter (VSC) system, the commutation failure of LCC can be restrained by making use of the VSC. A novel commutation failure suppression strategy based on reactive power clamp control is proposed in this paper. Firstly, the topology and characteristics of LCC-VSC system are introduced. Secondly, the mechanism of VSC to suppress the commutation failure of LCC is studied. In case of faults, the maximum reactive power setting of VSC is clamped to suppress the commutation failure of the LCC, the commutation failure immune factor and commutation failure probability index are improved. Finally, a receiving-end hybrid LCC-VSC model is built in PSCAD / EMTDC for simulation analysis. The simulation results show that the control strategy can significantly improve the ability of LCC-HVDC to withstand commutation failure and improve the system fault recovery characteristics.