Research On Photovoltaic Water Pumping System Based On Z Source Inverter

With the continuous development of science and technology,the industrialization process has accelerated year by year,but the excessive exploitation of non-renewable energy sources such as fossil fuels has also caused the problem of energy shortage,therefore,the development and utilization of renewable energy has become an important way to alleviate the energy shortage.In renewable energy sources,the development and utilization of solar energy has received extensive attention,which is due to the advantages of wide sources of solar energy,strong renewability,low cost,environmental protection and energy saving.Solar energy conversion technology shows great value,the way for solar energy to achieve energy conversion is to focus on photoelectric conversion.This thesis analyzing the practical application of solar photovoltaic conversion,take the photovoltaic water pumping system as an example.From the perspectives of energy conversion efficiency and stability,the research focuses on the Z source inverter control strategy and the pump motor speed control method.This research based on the photovoltaic water pumping system.The control strategy and speed regulation method are verified by the model.Firstly,under the conditions of different sunshine intensity and temperature,this thesis' s system pre-stage simulation of the MPPT(Maximum Power Point Tracking)link is emphasized to ensure the tracking of the maximum power of the photovoltaic water pumping system,and make the photovoltaic water pumping system always runs at maximum power successfully.Thepre-stage system simulation is mainly based on the photovoltaic cell equivalent model,and the PU and UI curves are respectively obtained on this basis.Secondly,the control method of Z-source inverter is studied.The main function of the Z source impedance network in this thesis is to achieve the purpose of stabilizing the DC link voltage indirectly by detecting the capacitor voltage continuously,and thus functioning as a buck-boost for the system.In this thesis,the Z-source inverter model is constructed to discuss the buck-boost mode,and the SPWM algorithm is used to achieve the matching between the system motor power and the PV array.Thirdly,the photovoltaic water pumping system designed in this thesis uses a centrifugal submersible pump,which uses a three-phase asynchronous motor terminal.This thesis studies the motor control strategy,the motor control method in this thesis is vector control method..Finally,this thesis establishes three modules of photovoltaic array,frequency conversion main control and machine pump load,and carries out analysis through MATLAB/SIMULINK software platform to realize parameter debugging and detection of the above three modules.Based on the simulation optimization parameter design,the three modules of PV array,frequency conversion main control and machine pump load are assembled to form a complete photovoltaic water pumping system.The simulation results show that improved photovoltaic water pumping system can adjust the water pump in real time according to the sunshine intensity and temperature change,and finally realize the coordinated operation between the photovoltaic array and the pump load.