Research on reactive power characteristics of CCC inverter and its improved control strategy

This paper based on the commutation mechanism of series capacitor commutated converter (CCC), the CCC is applied to UHVDC transmission system, and the mathematical model of reactive power demand of CCC inverter is established. According to the actual parameters of Jiuquan-Hunan ±800 kV UHVDC transmission project, the simulation model of CCC- UHVDC system is built by PSCAD/EMTDC simulation software. Beside, combination of the changing characteristics of the DC current and the relationship between the electrical variations during the system failure, a method of parameter optimization especially for VDCOL input voltage is proposed, thus suppressed the DC peak current and improved the performance of reactive power characteristics, finally implement the control method by means of simulation software. Simulation results shows that CCC has the stronger ability to resist commutation failure. It also validates the effectiveness of the proposed parameter optimization method.