基于虚拟磁链反馈控制的跟/构网型MMC暂态稳定性提升方法OA

The modular multilevel converter(MMC)based high voltage direct current(HVDC)transmission is an important approach to the large-scale integration of renewable energy.In areas where renewable energy is concentrated,the insufficient transient stability margin has become one of the key factors limiting the transmission section limits.To address the transient instability of MMC caused by large-signal disturbances,a virtual flux linkage feedback control is introduced without altering the original control structure,thereby enhancing the transient stability capability and prolonging the critical clearing time of the grid-following and grid-forming MMCs.By deriving the impedance characteristics of grid-following and grid-forming MMCs and the power angle characteristics of the grid-forming MMC before and after adding virtual flux linkage feedback control,it is found that the virtual flux linkage feedback control can reduce the resonant peak and enhance the phase angle stability margin of both grid-following and grid-forming MMCs,and shift the power angle characteristics of grid-forming MMC upward,endowing it with a natural characteristic of"large deceleration area and small acceleration area".The effectiveness of the proposed control strategy and the correctness of the theoretical derivation results are verified through the two-terminal MMC-HVDC system and the 3-machine 9-bus system based on PSCAD/EMTDC and the hardware-in-the-loop(HIL)experiments.