A Novel Strategy for Preventing Commutation Failures During Fault Recovery Using PLL Phase Angle Error Compensation

Existing studies on commutation failure during fault recovery (CFFR) in line-commutated converter high-voltage direct current (LCC-HVDC) systems often neglect the critical influence of phase-locked loop phase tracking error (PLL-PTE) and fail to provide effective control strategies to address this issue. This paper investigates the influence of PLL-PTE on CFFR through electromagnetic transient simulations based on a modified CIGRE benchmark model. The study reveals that phase angle jump (PAJ) caused by DC power fluctuations (DPF) and AC network reconfigurations (ANR) is the fundamental source of PLL-PTE, which in turn leads to the occurrence of CFFR. To mitigate this, a novel control strategy is proposed that dynamically adjusts the extinction angle based on historical and predicted PAJ data. Simulation results demonstrate that the proposed method effectively suppresses CFFR under various fault conditions, including different fault types, locations, resistances, and initiation times. Compared with existing control schemes, the proposed approach avoids adverse side effects while exhibiting strong robustness and adaptability. The proposed control strategy significantly enhances the stability and reliability of LCC-HVDC systems, offering great potential for practical application in increasingly complex power grid environments.