Frequency Coupling Admittance Modeling of Quasi-PR Controlled Inverter and Its Stability Comparative Analysis Under the Weak Grid

This paper intends to comparatively study the stabilities of grid-connected inverters with three closely related controllers: quasi-proportional resonance (quasi-PR), proportional integral (PI), and (PR) under weak grid. Firstly, considering influence frequency coupling characteristic, a admittance model quasi-PR controlled inverter is established. Then, characteristics quasi-PR, PI PR are compared. Admittance similar while quite different: amplitude larger than that phase difference between two obvious in mid-high areas, which mainly caused by bandwidth controller. Furthermore, analyzed. The but more sensitive grid high output power. To achieve same system stability, voltage outer-loop should be designed narrower inverters. Finally, experiments verify correctness analyses.