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Research on Suppressing Continuous Commutation Failure of HVDC System Based on Virtual Capacitor

In order to solve the problem that continuous commutation failure in HVDC transmission system has a serious impact on the operation of HVDC system, the mechanism of commutation failure of HVDC system is analyzed, and the concept of virtual capacitor is introduced. The virtual capacitor is used as the carrier of DC voltage change rate, and combined with low-voltage current limiting control, the continuous commutation failure of HVDC transmission is suppressed. The method of introducing virtual capacitor can reflect the dynamic characteristics of DC voltage during fault and recovery process. Through the electromagnetic transient model of HVDC system, it is verified that the proposed method can effectively suppress the continuous commutation failure of HVDC system under single-phase fault and three-phase fault, and accelerate the recovery of the system after fault.