Application Of Fractional Order PI~λ Controller On Single-phase Photovoltaic Grid-connected Inverter

In recent years, with the environment destruction and the exhaustion of fossil raw materials, photovoltaic power generation is becoming increasingly popular among people in modern society. Of the numerous forms of photovoltaic power generation systems, non-isolated two levels of single-phase photovoltaic grid system has been widely applied in the study of single-phase photovoltaic grid, for photovoltaic grid inverter’s small volume, light quality, high efficiency and low cost.In photovaltaic grid inverter system, the inverter is the core part,the choice of control strategy of grid-connected pv plays a decisive role in its system performance.The fractional order μλDPI controller extends controller order of traditional PID to the fractional domain, which has better control effects than PID controller. In this paper, the research work which from the digital implementation、 parameters optimization of the fractional order μλDPI controller has been done. The experimental result shows that the fractional order μλDPI controller is superior to the PID controller in the control effects.In order to realize single-phase photovoltaic grid, this paper researches the grid system module about maximum power point tracking(MPPT)、Boost chopper circuit and inverter circuit. First of all, set up photovoltaic cell model in MATLAB/Simulink, and analyze the illumination and temperature’s influence on the photovoltaic cell output. Second, this paper completes the maximum power point tracking with two methods: incremental conductance method perturbation and observation method. The former can make photovoltaic cells work at maximum power point through a large number of calculations, but it isn’t easy to project implementation. The latter completes the maximum power point tracking through continuous sampling analysis, and it is simple and easy to project implementation. Then, using Boost circuit, complete the boost of photovoltaic cells output, output steady dc voltage, and provide bus voltage to inverter circuit. And then, this paper finishes the level inverter circuit simulation on the basis of completing the front-end circuit. In order to improve dynamic characteristic of grid inverter, reduce harmonic component of grid current, fractional order PI~λ controller is preferred for the choice of controller. Because applied on the inverter inner loop control it has a greater adjustment range and better control effects than PI controller. The experiments show that the output current conform to the requirements of the grid, which can effectively reduce the harmonic component, and obtain better control effects than the PI; Finally, the paper studies the overall single-phase photovoltaic grid inverter system, completes the construction of the whole model. The whole model output reaches the grid-connected requirements, through the study of current voltage double closed loop control strategy and completes the fractional order PI~λ controller in the application of photovoltaic(pv) grid inverter experimental study.