Commutation Failure Predictive Control Based on Fast AC Voltage Measurement in LCC-HVDC

Abstract

To inhibit commutation failure (CF), in this paper, the influence factors of CF were analyzed, and considering different fault types and different valves, the mathematical expression of extinction angle was deduced. In addition, by analyzing existing control strategies for inhibiting CF, it is indicated that existing control strategies cannot quickly and accurately obtain the AC voltage amplitude and zero-crossing phase shift angle. To solve this problem, this paper proposed a fast AC voltage measurement method, and the zero-crossing phase shift angle can be calculated by AC voltage amplitude. On this basis, a commutation failure predictive control method (CFPCM) was proposed to inhibit CF. The CFPCM can adapt to all fault types. Finally, based on the CIGRE HVDC benchmark model, the commutation failure prevention module (CFPREV) and CFPCM simulation model were built using PSCAD/EMTDC to verify the effectiveness of the proposed CFPCM. The simulation results showed that the CFPCM can not only inhibit CF more effectively, but also reduce the fluctuation of DC current, AC voltage, and extinction angle with a fault occurred in the inverter AC system.

Keywords

• Commutation failure
• DC current
• HVDC
• predictively control
• extinction angle