A novel sliding‐mode control strategy for MMC under parameter uncertainty in HVDC power system

Currently, the main control strategy of the modular multi‐level converter (MMC) is a combination of vector control (VC) and proportional‐integral (PI) control, which allows decoupling active and reactive power control and maintaining the power balance within the high voltage direct current (HVDC) system. Although the existing PI control or conventional sliding mode control (SMC) shows a satisfactory control performance under steady state, its robust performance is poor when parameter uncertainty occurs, which greatly affects the stable operation of MMC. Therefore, a novel interval sliding mode control (ISMC) for MMC‐based HVDC systems is proposed in this paper, along with the stability criterion and design procedure. The proposed method can attenuate the influence of the parameter uncertainty, make the system robust and stable, and achieve both satisfactory transient and steady‐state performance under parameter uncertainty. The comparative simulation experiments of PI control, conventional SMC, and ISMC for MMC were conducted in PSCAD/EMTDC, demonstrating that the proposed ISMC shows better robustness and tracking performance than either PI control or SMC under different disturbance working conditions.