Calculation of Main Circuit Steady-State Parameters for Capacitor Commutated Converter System

The calculation of the main circuit parameters is the basic part of the engineering design for high voltage direct current (HVDC) transmission systems. Compared to the conventional line commutated converter (LCC), the application of the capacitor commutated converter (CCC) can reduce the probability of commutation failures and the shunt capacitor reactive compensation. This paper proposes a calculation method of main circuit parameters for the CCC-based HVDC system. Firstly, the topology of a CCC-HVDC transmission system is described. Secondly, based on the steady-state mathematical model of the CCC, the paper proposes the calculation method of the commutation capacitor to satisfy the system requirements, and the calculation formulas of the main circuit parameters are also given. Then the calculation procedure of the main circuit steady-state parameters is described in detail considering system parameters, control modes, calculation tolerances and operating conditions. Finally, a two-terminal +/- 500 kV/3000 MW LCC-CCC HVDC transmission system is presented to verify the validity of the main circuit parameter calculation method. The proposed method has great significance for the AC filter design in practical engineering application.