For long distance and large capacity transmission problems, high-voltage direct current HVDC transmission is a suggestive alternative. In the design and construction process of HVDC transmission project, analysis on overvoltage and resonance characteristic of key equipment is indispensable. This paper employs a method to construct a broadband model for the converter valve. The Vector Fitting (VF) method is adopted to get a fitting curve with frequency impedances measured off at hundreds of sample points. Afterwards, the corresponding passive equivalent circuit is built via passive algorithm and synthesis procedure. The applicability of the method to our model is confirmed by comparing the simulated and measured data. The voltage distribution of the valve module composed of the key components under overvoltage is characterized, in favor of which the key components can be optimized.

broadband equivalent circuit model, converter valve, overvoltage analysis, passive, Vector Fitting