Research on the Power Coordinate Control Strategy between a CLCC-HVDC and a VSC-HVDC during the AC Fault Period

The underlying cause of commutation failures in traditional line-commutated converter (LCC) high-voltage direct-current (HVDC) transmission technology lies in the sensitivity of the thyristor devices, which are prone to turning off, thereby restoring the forward circuit breaker capability. This paper presents a coordination strategy between a controllable line-commutated converter (CLCC) and a voltage-sourced converter (VSC) and delves into the fault characteristics specific to CLCC damage. Our research focuses on CLCC topology, where fully controlled devices are incorporated to manage the thyristor’s turn-off time, ensuring its successful deactivation. This approach serves as a fundamental preventative measure against commutation faults. Furthermore, we employ a coordination strategy between the VSC and the CLCC to enhance the recovery time efficiency of the AC system. This strategy is simulated and validated using PSCAD software, and the results confirm its effectiveness in fault tolerance and AC system recovery.