A Novel Control Strategy for Suppression of HVDC Subsequent Commutation Failure

In the case of AC failures at the receiving end of the HVDC system, commutation failures are likely to occur, which may cause the converter station to lock up and seriously threaten the safety of the power grid. In order to suppress the subsequent commutation failure of HVDC, this paper studies the response of the electrical quantity and the control quantity when the system is in the recovery process. The DC current and the firing angle are not coordinated, resulting in insufficient commutation voltage-time area margin and the inability to complete the commutation process. For this reason, this paper proposes a subsequent commutation failure suppression strategy. By limiting the DC current when the firing angle overshoots, the subsequent commutation failure is suppressed to achieve effective recovery of the DC system. The CIGRE standard test model is used in EMTDC to test and verify the proposed theory.