Adaptive Second-Order Sliding Mode Control for Grid-Connected NPC Converters With Enhanced Disturbance Rejection

• Published in: IEEE transactions on power electronics Vol. 37; no. 1; pp. 206 - 220
• Main Authors: Shen, Xiaoning, Liu, Jianxing, Marquez Alcaide, Abraham, Yin, Yunfei, Leon, Jose Ignacio, Vazquez, Sergio, Wu, Ligang, Garcia Franquelo, Leopoldo
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.01.2022; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Adaptive control; Control methods; Control systems; Controllers; Converters; Electric potential; High gain; High-gain observer (HGO); Noise measurement; Observers; Performance degradation; power converter control; Power measurement; second-order sliding mode (SOSM); Sliding mode control; State observers; Switches; three-level neutral-point-clamped converter; Voltage; Voltage control; Voltage measurement
• ISSN: 0885-8993; 1941-0107
• DOI: 10.1109/TPEL.2021.3099844

In this article, a two-stage control scheme consisting of an adaptive-gain second-order sliding mode (SOSM) controller and a switched high-gain observer (HGO) is proposed for the three-level neutral-point-clamped (NPC) converter. The adaptive-gain SOSM control method is applied both in the voltage regulation loop and instantaneous power tracking loop, thus, the boundary of the disturbance derivative does not need to be known a priori . Compared with the fixed-gain SOSM, it provides a faster dynamic and a better steady-state response for the NPC converter. On the other hand, the conventional disturbance compensation observer used in the power system suffers from the adverse effects of measurement noise, which limits the performance of the observer. A switched HGO is combined with the adaptive-gain SOSM controller in the voltage regulation loop to address this issue. By using a switched observer gain, the switched HGO greatly diminishes the performance degradation induced by the inevitable measurement noise. Finally, several experiments between the representative extended state observer-based SOSM control scheme and the proposed control method are carried out for a comparison. The results demonstrate the feasibility and effectiveness of the proposed approach.