Key points are not available for this paper at this time.
The hybrid cascaded (HC) LCC-MMC HVDC scheme, wherein the LCC serves as the rectifier, and a single LCC is connected in series with multiple MMCs in parallel as the inverter, amalgamates the merits of both LCC and MMC technologies. However, the utilization of thyristors in the LCC inverter still introduces a potential risk of commutation failure (CF). To mitigate this concern and bolster the stability of the hybrid system, an analysis of the LCC CF and its recovery process is undertaken, along with a mathematical investigation of the LCC's reactive power (RP) characteristics in the inverter. Subsequently, a mitigation strategy rooted in RP feedback control (RPFC) for the subsequent CF (SCF) within the HC-HVDC system is proposed. The transient performance of the system under AC fault conditions is evaluated with the proposed control approach in comparison to conventional methods. The outcomes indicate that this proposed approach effectively harnesses the RP support capabilities of MMCs, thereby endowing the LCC with enhanced resistance to potential SCF and improved post-fault recovery performance for the overall system.
Liu et al. (Thu,) studied this question.