Research on Passivity-Based Control of a Single-Phase Grid-Connected PV Inverter under Weak Grid

• 1、School of Electrical Engineering and Automation, Harbin Institute of Technology, Harbin 150001

Abstract：Under weak grid, the large grid impedance may result in the decrease of the grid power quality and even instability of the inverter control system. Therefore it is significant to investigate a control strategy with more stable robustness and simple algorithm for the PV inverter under weak grid. As a non-linear control strategy, the passivity-based control has advantages in its strong stability and robustness, good dynamic response performance and simple algorithm, so this paper investigates a passivity-based control (PBC) strategy applying in the single-phase grid-connected PV inverter under weak grid. First, an Euler-Lagrange (EL) model is built as a basis of designing the PBC. And then this paper analyzes the passivity property of the inverter. Next, the PBC controller is designed through damping injection. The control performance would be discussed later, and a detailed parameter design of the injected damping is intruoduced. At last the validity of the proposed PBC strategy is verified through simulations. The results indicate that the proposed PBC strategy has a strong robustness when the grid impedance and grid voltage fluctuate.

Keywords： Grid-connected PV inverter Passivity-based control Weak grid Euler-Lagrange model