Model‐Based Discrete Sliding Mode Control with Disturbance Observer for Three‐Phase LCL‐Filtered Grid‐Connected Inverters

Abstract

Grid‐connected voltage source inverters with LCL filters have been widely used for distributed generation systems in renewable energy systems. The presence of LCL resonance influences the overall performance and complicates the system control design, especially when the uncertainties caused by the component parameter variations and disturbances are considered. In order to improve the system performance under uncertain conditions, this paper presented a model‐based discrete sliding mode control (SMC) with disturbance observer (DOB) for three‐phase LCL‐filtered grid‐connected inverters. In this work, the inverter model is modified by using a virtual damping resistor to eliminate the resonance of the LCL filter and improve the stability, even consider the variations of the grid impedance. To save the sensors and predict the forward step of the state variables, a discrete state observer is adopted in the control. To enhance the robustness of the system, a DOB is designed in the SMC controller to estimate the disturbances so that the system uncertainties can be effectively compensated. Finally, comparative simulations and experiments are constructed to demonstrate the effectiveness of the proposed method. © 2020 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.