A method for suppressing commutation failure based on dynamic adjustment of the minimum extinction angle of thyristors

The minimum extinction angle <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\gamma_{\min})$</tex> of thyristors is a quantity that dynamically changes with the system operating conditions. When the extinction angle <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\gamma$</tex> is less than its minimum value, a phenomenon of commutation failure will occur. In order to reduce the risk of commutation failure in practical engineering, considering the dynamic change process of extinction angle during the system operation, a dynamic control strategy for the extinction angle based on the measured minimum value of thyristors has been proposed in the paper. To verify its effectiveness, a CIGRE LCC-HVDC benchmark model was developed on the PSCAD/EMTDC V5 software platform. Simulation analysis shows that <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\gamma_{\min}$</tex> has a significant impact on the stability of systems under fault conditions. The proposed method can effectively suppress commutation failure induced by different types of faults, which is beneficial for increasing the margin of extinction angle and has guiding significance for practical engineering.