Inhibition of Subsequent Commutation Failures in Ultra-High Voltage Direct Current Transmission Systems Using Electrochemical Energy Storage at the Sending End

Introduction: Subsequent commutation failures (SCFs) in high-voltage direct current (HVDC) systems pose a serious threat to the safe operation of hybrid AC/DC grids. Electrochemical energy storage, which is widely distributed at the sending end of ultrahigh voltage direct current (UHVDC) transmission systems, has the potential to mitigate SCFs. To fully harness the SCF-mitigating capabilities of energy storage, this article first establishes a CIGRE-HVDC standard test model incorporating electrochemical energy storage at the sending end. Method: Based on this model, the factors influencing DC commutation failures are investigated. Furthermore, the impact of rectifier-side electrochemical energy storage (EES) on inverter-side commutation failures is explored from three aspects: energy storage capacity, output magnitude, and fault conditions. It is found that rectifier-side EES absorbing power can effectively suppress inverter-side commutation failures. Finally, based on this finding, a transient active power control strategy for energy storage is designed to inhibit consecutive commutation failures and is studied on the CIGRE-HVDC standard test system. It is concluded that the optimal capacity for suppressing SCFs is between 20% and 30% of the DC capacity, and the best absorption power output is achieved with a per-unit value of 1. Result: Simulation results confirm the correctness of the proposed energy storage transient active power control strategy and its effectiveness in suppressing SCF under different fault moments, fault severities, and fault types. Conclusion: This strategy can limit the number of SCFs to three or fewer in the majority of operating conditions, facilitating rapid system recovery after faults.