Abstract:Renewable energy connected modular multilevel converter high-voltage direct-current (MMC-HVDC) system should have the capability of fault ride-through when the AC grid fails. However, it is difficult to quickly and reliably achieve fault ride-through via cooperative control if there is no high-speed communication between renewable energy and MMC-HVDC converters. Additionally, the droop coefficient in traditional voltage drop control is set to a linear constant, which makes it difficult to fast match under different fault conditions and results in a longer step delay, leading to high voltage operation of the DC system during the fault. Aiming at the existing problems mentioned above, the dynamic characteristics of the DC system and the principles of traditional voltage drop control are analyzed, which provides a basis for fast power matching on both sides of the DC system. Then, a fault ride-through control based on fast matching power for renewable energy connected MMC-HVDC is proposed. Finally, simulations based on PSCAD/EMTDC show that fault ride-through capability is reliable by using the proposed control method. Compared with traditional voltage drop control, the proposed control method significantly reduces the step delay, limits the rise of DC voltage and achieves fast and reliable fault ride-through.