Application Of The Passivity-based Control Theory In LCL-type Grid-connected Inverter

The rapid evolution of society and technology has led to a significant increase in energy demand.The consumption of fossil fuels and the environmental problems caused by them are forcing the whole society to focus on the use of renewable energy sources such as wind and solar energy.Distributed power generation systems(DPGS)such as solar and wind power are growing steadily worldwide.In DPGS,grid-connected inverters based on LCL filters are being widely used,and the control performance is directly related to the power quality of the grid current.The passivity-based control theory,a kind of global stability control strategy,is widely concerned with its simply derivation method and easy to implement and strong robustness.This paper studies the application of the passive control in grid-connected inverter with LCL filters.Firstly,the mathematical model of LCL-type grid-connected inverter under weak grid is established.Based on the analysis of the influence of the internal resistance of the inductor and capacitor and grid-side impedance on the inherent characteristics of the filter,the model of the grid-connected inverter is simplified.From the simplified model,the theoretical derivation of the passivity-based control algorithm is carried out,and the traditional passivity-based control strategy of grid-connected inverter based on LCL filter is obtained.The global stability of the control system can be obtained by the control strategy.As the traditional passivity-based control strategy for derivation does not provide sufficient damping in the case of LCL filter,a active damping control strategy based on capacitance voltage error feedback is proposed and the PR controller is introduced into the control loop.After comparison and performance analysis,the proposed improved passivity-based control strategy not only realizes the global stability of the control system,but also provides sufficient damping for the control system and can achieve zero tracking error.Finally,the Matlab/Simulink simulation model and experimental platform are built to simulate and verify the proposed passivity-based control algorithm.Both simulation and experiments verify the good control effect of the proposed improved passivity-based control strategy.