Small-signal stability analysis of PV grid-connected inverter under weak-grid

摘要

For distributed generation system, the grid is no longer an ideal grid, but a weak grid which contains internal impedance. The grid impedance has a serious impact on system stability and power quality for PV grid-connected system. In this paper, the small-signal model and state equation of the grid connected system are established under weak-grid, the influence of grid impedance on system eigenvalue is analyzed. The sensitivity of each characteristic mode to the state variable is obtained by using the participation factor analysis, and the influence of each key parameter on the small disturbance stability of the system is analyzed. Lastly, the stability regions of single-system parameters, double-system parameters and multi-system parameters under different grid impedance are discussed. The analysis results show that the small disturbance stability of the PV system can be improved by adjusting the control parameters reasonably, which provides a theoretical basis for the optimal design of the controller.