An Improved Method of Coordinated Control for Commutation Failure Predictive Control of Multi-infeed DC Systems

Abstract

The invention discloses an improved method for commutation failure prediction control coordination control of a multi-feed direct current system. The improved method includes the following steps: predicting the arc extinguishing angle of the subsequent direct current commutation process of each circuit by considering voltage harmonics and direct current changes; The arc extinction angle is multiplied by the electrical coupling factor, which guides the output of the commutation failure predictive control. The improved method of the present invention takes into account the changes of AC voltage and DC current, and predicts the arc-extinguishing angle of the subsequent commutation process of each system; and then proposes a coupling coefficient between each circuit and DC considering the electrical distance, multiplied by the predicted value of the subsequent commutation process of each circuit and DC. Therefore, the evaluation indexes of each return DC margin considering the influence of reactive power interaction can be obtained, so as to realize the guidance and adjustment of the commutation failure prediction control output; it can effectively suppress the successive commutation failures of the multi-feed DC system, and is consistent with the existing Compared with the method, the response speed is improved to a certain extent and the coupling relationship between the DC circuits is considered.

Description

technical field [0001] The invention relates to the field of power system safety and stability analysis and control, in particular to an improved method for coordinated control of commutation failure prediction control of a multi-feed direct current system. Background technique [0002] The HVDC transmission project based on thyristor commutation is widely used because of its large transmission capacity and long distance. However, the DC densely fed AC system forms a complex multi-feed DC system, which poses a new challenge to the safe and stable operation of the power system. The electrical distance of the DC drop points in the multi-feed system is getting closer and closer, and the dynamic reactive power coupling relationship is getting closer and closer. The commutation failure caused by a single-circuit DC fault will cause the other DCs to have commutation failures one after another. The current commutation failure suppression strategies for multi-infeed HVDC transmissi...

AI Technical Summary

Problems solved by technology

Among them, CFPREV detects the voltage signal after the fault, and outputs the trigger angle in advance to increase the margin of the commutation process to suppress the commutation failure, but it lacks the consideration of the influence of reactive power interaction characteristics between the DC circuits, and the control effect of suppressing successive commutation failures remains to be seen. further improvement

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