The Stability Control Method Research Of Wind Power Converter With Grid Impedance Adaptation

With the continuous reduction of the total amount of traditional non-renewable energy,and environmental pollution and other issues have become aggravated,all this urged the development and utilization of renewable energy which represented by wind energy,solar energy and so on.The wind power converter is a necessary part of the electric energy generated by the wind power generator to be incorporated into the power grid,but the grid impedance which exists in the transmission network that connected to the converter and the power grid will influence the stability control of the wind power converter,so,the method of maintaining the stability of the wind power converter in consideration of the grid impedance is need to study,the main content is:(1)Based on the mathematical model of grid connected inverter with LCL filter,the control system of grid connected inverter was analyzed under the two phase stationary coordinate system,and the open-loop transfer function of current loop in the control system of grid connected inverter was derived,the stability of the control system when considering the grid impedance was analyzed by MATLAB simulation.(2)On the basis of the measurement principle of the injection of non-characteristic harmonics,the utilization of inherent harmonics of the system and the complex filter,an improved method of impedance measurement by injecting non-characteristic harmonics was studied,and built simulation model in MATLAB/SIMULINK,the simulation results showed that the designed method could realize the measurement of the grid impedance.(3)Carried on analysis to the design process of control parameters in the three phase grid connected inverter system when considering grid impedance,obtained the relation expression between control parameters and grid impedance,the simulation results showed that the control parameters which adapted to the impedance changed played a role in maintaining the stability of the control system.(4)Based on the relationship between the control parameters and grid impedance.The grid impedance adaptive control structure of grid connected inverter system was designed,and the simulation model was built in MATLAB/SIMULINK,the simulation results showed that compared with when the control parameters were not changed with the variation of the grid impedance,the three phase grid connected inverter system could maintain stability when the system control parameters could be adjusted by the variation of the grid impedance.