弱电网下跟/构网并联逆变器自适应控制策略OA

Under weak grid conditions,grid-following inverters(GFL)are prone to sub/super-synchronous oscillations,whereas grid-forming inverters(GFM)exhibit better adaptability to weak grids.The parallel operation of GFL and GFM can enhance the stability of grid-connected systems,but the configuration cost increases with installed GFM capacity.To improve the stability of parallel GFL/GFM inverter systems under weak grid conditions while reducing the required ca-pacity of GFM,an adaptive control strategy based on impedance detection is proposed.Firstly,the q-axis impedance mathematical models for both GFL and GFM are established.The Nyquist stability criterion is used to analyze the rela-tionship between GFL output oscillations and q-axis impedance under weak grid conditions.System stability at different short-circuit ratios and different GFM capacity configurations is also evaluated.Subsequently,an adaptive control strategy is proposed to reshape the GFM q-axis impedance when the installed GFM capacity is low,thereby enhancing the stability of the parallel system over a range of weak-grid strengths.The effectiveness of the proposed strategy is verified using MATLAB/Simulink.The research results demonstrate that the proposed control strategy can be adopted to effectively im-prove the operational stability of the parallel system under different weak grid conditions when the installed GFM capacity is low.