The flexible interconnection of the distribution network based on flexible DC and the hybrid AC-DC distribution network structure will bring great changes and challenges to the traditional operation mode of the distribution system. Based on combing the structure of MV DC distribution system and flexible interconnection device, the article proposes the control model of converter station of flexible interconnection system based on MMC and constructs the operation strategy of flexible interconnection system. The stability of the MV flexible interconnection system is simulated and analyzed by combining the output impedance model and equivalent circuit of the DC side of the flexible converter. In order to further improve the control effect of the MV flexible interconnection system accessing the distribution network, this paper combines the multi-intelligent body (MMC) system with the flexible interconnection control strategy, constructs the control and protection strategy of the MV flexible interconnection system accessing the distribution network, and carries out the simulation analysis of it. The results show that obvious resonance peaks can be observed in the Bode diagram of MMC, and the simulated measured and theoretical curves are in good conformity, and the optimized balanced control strategy of capacitor voltage of MMC sub-module can realize the balanced control of capacitor voltage and the amplitude of voltage fluctuation can be controlled within ±5% of the rated voltage of the capacitor. Relying on the system control and protection strategy established in this paper, the energy management control effect of the distribution network can be significantly ensured and the reliability of the distribution network can be enhanced.
