Research On Micro-grid Inverter Control Technology Based On FPGA To Realize FFT Filtering

Due to the double pressure of environmental pollution and energy exhaustion,we have made great efforts to develop clean renewable energy,and the micro grid technology has also made remarkable progress.As the best use of new energy,distribution system has also become a hot topic in the field of smart grid.The capacity of the micro-grid system is often small,and the quality of the voltage waveform of the system is easily affected by the load,and the stability of the system is reduced.In addition,the nonlinearity of power electronic devices in inverters caused the output port voltage waveform not smooth,which is mixed with a large number of high-order harmonics,and that affect the feedback of the system,increasing the control difficulty of the controller and the volume of the LCL filter circuit.Based on the above problems,this dissertation designed a control method with instantaneous value feedback of FFT filter used the energy sto rage inverter.First of all,this dissertation introduces the basic principle and operation law of FFT transform.According to the characteristics of only need to extracted base wave signals in this design,the simplified method of FFT transformation is proposed to further reduce the amount of operation.Due to the large amount of computation in the FFT transformation process,the conventional microprocessor is difficult to complete the computation in such a short time.Therefore,FPGA aided main controller is used in this design.Secondly,the control system structure and control strategy of energy storage inverter are analyzed.Aiming at the influence of harmonic components in feedback signal on control system,this dissertation propose a method of series FFT filter in feedback loop,and calculate the key parameters of filter.Through the analysis and study of the topology and mathematical model of the energy storage inverter,the simulation model of the energy storage inverter is built by Simulink.The feasibility and effectiveness of the method are verified by comparing the simulation experiments before and after the filter in the feedback loop.Finally,the overall technical plan of the design is systematically expounded,and the design of inverter hardware and software as well as the design methods of various sub modules implemented in FPGA are introduced.With the help of Quartus II,the design of feedback filter for energy storage inverter is realized by using Verilog HDL hardware description language.The feasibility,correctness and rapidity are verified in the Modelsim simulation software.