跟网与下垂构网变流器混联带负荷系统稳定域与稳定形态OA

Against the background of the accelerated development of new power systems,the deep coupling and hybrid operation of grid-following(GFL)and grid-forming(GFM)converters have become the norm.Most existing research focuses on the grid-connected scenarios,with limited investigation into their off-grid load operation.This paper establishes a load-carrying hybrid system with a single GFL converter and a single GFM converter with droop controller,and theoretically investigates the large-disturbance synchronization stability region of the hybrid system and corresponding stability state.First,the static stability limit of the system is analytically deduced,the existence condition and expression of the periodic stable equilibrium point(SEP)of the hybrid system are obtained.Then,based on the invariant manifold theory and the inverse trajectory method,the stability region and the corresponding stability state are analyzed,presenting three cases:1)When the output of the GFL converter exceeds that of the GFM converter,the stability regions of each periodic SEP are separated,and the stability states include convergence to the original SEP/instability;2)When the outputs of the GFL and GFM converters are comparable,the stability regions of each periodic SEP are adjacent but cannot cover the entire space,and the stability states include convergence to the original SEP/convergence to other SEPs/instability;3)When the output of the GFL converter is less than that of the GFM converter,the stability regions of each periodic SEP are adjacent and can cover the entire space,and the stability states include convergence to the original SEP/convergence to other SEPs.In addition,this paper analyzes the influence of key parameters on the stability region and stability states.As the droop coefficient increases,the proportional coefficient of the phase-locked loop increases,or the integral coefficient decreases,the system stability region expands.Finally,the electromagnetic transient simulations and hardware-in-the-loop experiments are conducted to validate the conclusions.