Model-Free Adaptive Synergetic Control to Improve Robustness and Transient Performance of Grid-Tied Inverters

For high-quality grid connections in distributed generation, the robustness and transient performance of grid-tied inverters (GTI) under various operating conditions are crucial. This article presents a novel model-free adaptive synergetic control (MFASC) approach, which can significantly improve the robustness and transient performance of GTI. To enhance the robustness and adaptability of GTI, and to avoid the effects of unmodeled dynamics, a compact form dynamic linearization model based on the system input/output information is established. Subsequently, in order to improve the response speed, a synergetic control law is designed by utilizing the rapid convergence of differential equations. To further enhance the dynamic performance, an overshoot suppression strategy is designed to suppress the dynamic overshoot through ensuring Lipschitz condition, and a <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</i>-factor adaptive law is designed to adjust the response speed and system oscillation by dynamically changing the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</i> parameter of the MFASC. Finally, the MFASC method is applied to the current control of GTI, and the validity is verified through simulation and experiment.