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摘要
Aiming at the problem that a LCC-HVDC transmission system is apt to cause continuous commutation failures (CCF) under an AC fault on the inverter side, this paper analyzes the mechanism of CCF in stages. It is clear that when the firing angle deviation occurs, the mismatch between the DC current and the actual firing angle is an important cause of the CCF. If an asymmetric fault occurs at that time, the negative sequence component affects the actual firing angle through the pole control and the valve control system, which may increase the risk of CCF. Therefore, a CCF suppression method based on the actual firing angle response is proposed, in which the current command of the rectifier side is corrected by the actual firing angle. At the same time, the method reduces the influence of negative sequence current on the command of firing angle of pole control by the notch filter, and reduces the influence of negative sequence voltage on the actual value of firing angle of valve control by the sequence decoupled resonant and the commutation voltage phase compensation. This method is able to realize the dynamic and adaptive current command adjustment, improve the matching degree between the DC current and the actual firing angle in the recovery process, and promote the ability of DC system to resist the CCF. In the CIGRE model and an engineering model, the correctness of the theoretical analysis and the effectiveness of the optimization method are verified. ? 2024 Power System Technology Press.
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