PROJECT TITLE :

Analysis and Enhanced Control of Hybrid-MMC-based HVDC Systems during Asymmetrical DC Voltage Faults - 2017

ABSTRACT:

This paper presents an enhanced control for HVDC systems using hybrid modular multilevel converters (MMCs) during asymmetrical dc voltage faults. The characteristics of pole-to-ground (PTG) fault beneath totally different system grounding schemes are analyzed. Then, the principle of enhanced control strategy to house the PTG fault is presented for a hybrid-MMC-primarily based HVDC system with symmetrical monopolar configuration. A brand new management variable is proposed on the arm voltages to distribute the facility transmitted from the ac side between the higher and lower arms. By adopting the enhanced management, the overvoltage and therefore the fault current will be eliminated when a PTG fault occurs. Furthermore, the hybrid-MMC-based HVDC system can operate continuously with adjustable active power and controllable reactive power by controlling the upper and lower arms of the converter asymmetrically throughout a fault amount. Finally, the feasibility of the proposed management theme is verified by simulation leads to PSCAD/EMTDC.