Research on ADRC controller of bidirectional DC–DC​ converter for MMC-BESS

Abstract

The flexible interconnection AC/DC hybrid system with modular multilevel converter (MMC) as the core interface can comprehend the centralized get right of entry to of different and decentralized resources, decorate the reliability of strength supply, and enhance new energy consumption. However, the intermittence and fluctuation of distributed generations affect the safety and stability of flexible interconnected AC/DC hybrid systems. MMC based on battery energy storage system (MMC-BESS) can stabilize power fluctuations on the AC and DC sides of the system and improve the stability of the system. In order to improve the rapidity and immunity of MMC-BESS, this paper presents an active disturbance rejection control (ADRC) strategy for the bidirectional DC–DC converter of MMC-BESS. The voltage fluctuations of the interface capacitor in the energy storage and the current fluctuations of the inductor in the bidirectional DC–DC converter are discussed. Moreover, ADRC controller is designed for the bidirectional DC–DC converter of MMC-BESS. At last, simulations under different load mutations on the DC side and unbalanced three-phase grid voltage are carried out for verification of the performance of the ADRC control strategy in MMC-BESS. The results show that MMC-BESS based on ADRC strategy has more favorable rapidity and immunity than PI strategy, and is helpful to practical application in flexible interconnected AC/DC hybrid system in the future.