Impedance-based stability analysis of single-phase inverter connected to weak grid with voltage feed-forward control

Voltage feed-forward control (VFFC) is widely used due to its good low-frequency-harmonics suppression and easy implementation, however, it will worsen system stability under the weak grid condition. In this paper, the stability of single-phase grid-connected inverter with VFFC is studied based on impedance analysis method. With this method, the instability mechanism and the unstable area caused by VFFC are easily obtained. Based on this, system can be stabilized simply by adding phase-lead compensation, avoiding the real-time detection of grid impedance. Simulation and experimental results verify the analysis and the proposed control method.