Research On Single-Phase Grid-Connected Inverter Based On Frequency Adaptive PR Controller

With the maturity of new energy power generation technology,solar energy,as a new energy source,has become a hot research topic in the field of scientific research with the advantages of small pollution,abundant resources and easy to use.As a bridge and link between the new energy power generation system and the public power grid,the grid-connected inverter can convert the electric energy generated by the new energy power generation system into an alternating current that meets the grid connection standard.For inverters to work properly,grid-connected control technology is essential.In this paper,a frequency-adaptive-based PR controller is proposed,which can achieve no static tracking of grid voltage,better control effect when frequency fluctuations change,and improve the narrow bandwidth of PR controller.In this paper,the single-phase grid-connected inverter is selected as the research object.The third-order LCL filter is selected to filter out the higher harmonics,and the characteristics of the LCL filter are analyzed to obtain the transfer function,thereby obtaining the inductance and capacitance of the filter.Value;for the resonant peak problem of LCL type filter,the two methods of passive damping and active damping are introduced,and the active damping is determined.The advantages and disadvantages of PI controller and PR controller are analyzed in detail.A frequency adaptive PR controller is proposed.For the phase and frequency information required by the frequency adaptive PR controller,the phase-locked loop and the frequency-locked loop under the second-order generalized integration are introduced in detail,and the two are combined to obtain the phase and frequency.Finally,from the overall research,a 2kW single-phase grid-connected inverter prototype was designed,and the design rationality was verified by the design of the hardware circuit and the design of the control software.The prototype with DSP28335 as the control core is built,and the feasibility of the proposed frequency adaptive PR controller is verified by experiments.