Research on technical requirements of line-commutated converter-based high-voltage direct current participating in receiving end AC system's black start

This study discusses the technical requirements of line-commutated converter-based high-voltage direct current (LCC-HVDC) power transmission participating in a receiving end AC system's black start. The control and start-up modes of LCC-HVDC suitable for black start are discussed. Through short-circuit capacity analysis and frequency estimation, the appropriate strength of the receiving end AC system to start the LCC-HVDC is studied. A reactive power coordination strategy is proposed to reduce overvoltage caused by the HVDC filter. An innovative additional frequency control at the inverter side is proposed to suppress the frequency oscillation in the black-start procedure. This control is realised through the constant voltage at rectifier and constant current at inverter control mode. Compared with the conventional rectifier-side additional frequency control method, the inverter-side additional frequency control method requires no remote communication and is thus more practical and effective when the receiving end is in a blackout. On the basis of the analysis, the conventional LCC-HVDC is started successfully under the proposed requirements of black start and the overvoltage and frequency oscillation are also reduced effectively by the proposed control strategies, both of which are validated through electromagnetic transient simulation based on PSCAD/EMTDC software.