Optimization of Switching Thresholds for Main and Auxiliary Branches of Novel Controllable Commutation Converter

In this paper, an optimization method is proposed for the switching of the main and auxiliary branches of a Novel Controllable Commutation Converter (CLCC). Based on the theoretical model of commutation failure, the AC-side ground fault is decomposed into a DC component, harmonic component and overvoltage component, and a multidimensional fault dataset is constructed by combinatorial analysis. Using the Radviz visual multidimensional data analysis method, the correspondence between the control-and-protection thresholds of CLCC main- and auxiliary-branch switching under multi-component conditions is established, and the optimal switching thresholds under different short-circuit conditions of the AC system are determined. Finally, the validity of the method is verified by a field artificial short-circuit test, which provides theoretical basis and technical support for the reasonable determination of field setting.