To enable distributed PV to adapt to variations in power grid strength and achieve stable grid connection while enhancing operational flexibility

it is essential to configure grid-connected inverters with an integrated grid-following control mode

allowing smooth switching between GFL and GFM modes.First

impedance models of GFL and GFM PV energy storage VSG systems were established

and grid stability was analyzed.Second

an online impedance identification method based on voltage fluctuation data screening was proposed to enhance the accuracy of impedance identification.Additionally

a PV energy storage GFM/GFL VSG smooth switching method based on current inner loop compensation was introduced to achieve stable grid-connected operation of distributed photovoltaics under changes in strong and weak power grids.Finally

a grid stability analysis was conducted on the multi-machine parallel PV ESS

and a simulation model of a multi-machine parallel PV ESS based on current inner loop compensation was established for testing.Results showed that

compared to using a single GFM or single GFL control for the PV VSG system

the smooth switching method of multimachine parallel PV ESS effectively suppresses system resonance under variations in power grid strength

enabling adaptive and stable grid-connected operations of distributed PV.