An Adaptive Backstepping Sliding Mode Control Strategy for Single-phase Grid-Connected Inverter System under Weak Grid

Abstract

To overcome the adverse effect of uncertainty and external disturbance on the quality of grid-tied current in LCL-type single-phase grid-connected inverter system under weak grid, a novel adaptive backstepping sliding mode control (ABSMC) strategy is proposed. Firstly, the imprecise dynamic mathematical model of the single-phase grid-tied inverter system with uncertainties is established. And then to overcome the shortcoming that traditional backstepping control relies on accurate model, this method is combined with another method with strong robustness to realize the global stability of the system and have strong robustness to the uncertainties in the system. Furthermore, in order to weaken the chattering phenomenon of SMC, the adaptive control is embedded in backstepping sliding mode control to adjust the switching gain value in real time. The experimental results show that the proposed control method is robust to the changes of filter parameters and grid impedance. In addition, the third-order LCL inverter system is divided into three subsystems to gradually design the virtual control input, which makes the design process simple, and this nested design process ensures the asymptotic stability of the whole system.