Research On Three-Phase Photovoltaic Grid-Connected Power Generation System Based On MPPT

Now the energy is getting scarce,and the environment has been destroyed.How to develop and use solar energy has become an important issue in human development.Photovoltaic power generation is an important technology to use solar energy.Therefore,it is of great research significance and application prospect to study the photovoltaic grid-connected power generation based on the maximum power point tracking(MPPT)technology to improve the solar energy conversion efficiency.In this paper,three-phase photovoltaic grid-connected system as the research object,mainly to explore the system of maximum power point tracking and inverter control and some key technical issues,the main contents are as follows:First introduced the principle of photovoltaic cells and the composition of the system,the mathematical model of photovoltaic cell equivalent is established,and the influence of sunshine change and temperature change on photovoltaic cell is analyzed.And then based on three-phase photovoltaic grid-connected research,this paper introduces the classification of grid-connected inverter and the circuit structure of three-phase grid-connected converter,and deduces its mathematical model.And the mathematical model is established under the two rotating coordinates(d-q)by means of the idea of coordinate transformation.Decoupling is carried out by decoupling control of the model.The voltage control vector is controlled by the design of the PI regulator,which can improve the stability of the control system by adding the voltage feedforward link to improve the dynamic process and reduce the impact on the power grid.Then the maximum power output point of the photovoltaic cell is introduced.By comparing and analyzing the advantages and disadvantages,the Boost circuit is selected as the booster circuit.Some non-linear control algorithms are introduced for the commonly used MPPT algorithm,and their advantages and disadvantages are analyzed.And according to the problem of the conductance increment method,a kind of the scheme is proposed.Finally,the control of MPPT is realized.Because the single-stage grid-connected inverter system control is more complicated,the two-stage grid-connected inverter MPPT control system is adopted.By comparing the two MPPT control systems,the MPPT control system is selected,which has better MPPT control performance.Although the DC bus terminal is poorly regulated,it can be suppressed by voltage feedforward control voltage fluctuation.Finally,through the Matlab/Simulink software,build the system model,by changing the lighting changes,we can see that the battery output waveform can be very good to follow the light changes,with good dynamic response.And can be successful and network,anti-interference ability.It's can be a good validation of the control algorithm and strategy.