Hybrid HVDC for integrating wind farms with special consideration on commutation failure

This paper presents the control and operation of a hybrid HVDC system comprising a wind farm side VSC rectifier and a grid side LCC inverter for integrating wind power. The configuration and operation principle of the hybrid HVDC system are described. Commutation failure in the LCC inverter during an AC network disturbance is considered and its impact on the hybrid system operation is analyzed. An enhanced control strategy for the LCC inverter at the grid side and an alternative MMC topology using mixed half-bridge and full-bridge modules considered for the rectifier at the wind farm side are proposed. Simulation results using Matlab/Simulink are presented to demonstrate the robust performance during LCC inverter commutation failure to validate the operation and recovery of the hybrid system with the proposed control strategy and MMC configuration.