The converter valve is one of the key equipment in high-voltage direct current converter station and its broadband characteristics are a matter of great concern. In this paper

the thyristor converter valve is taken as the object and a passive broadband equivalent circuit model for the converter valve is set up. The vector matching method is used to perform rational function approximation of the frequency impedance characteristics of thyristor

grading capacitors

and resistance capacitance circuits and a rational polynomial in pole residue form is obtained. The principle of network synthesis is used to decompose and synthesize rational polynomials and obtain a broadband active circuit network. Based on the condition of port passivity

sequential quadratic programming method is used for port passivity optimization

and global optimization algorithm is used for strict passive optimization to obtain the passive broadband equivalent circuit model of the converter valve.