Photovoltaic Grid-connected System Research And Design Based On Filtering Backstepping

With the development of the global economy, the traditional energy of fossil tends to deplete, so human pay more attention on the development of new green energy. The energy of solar is a kind of widely distributed, inexhaustible, clean and renewable energy, which is accepted by more and more people. Photovoltaic (PV) grid-connected power generation is an important way of solar energy utilization. As the main equipment of photovoltaic grid-connected power generation, the performance of photovoltaic grid-connected inverter decides whether the photovoltaic power generation system can transfer high quality, reliable power to the grid. Therefore, it is importantly practical significance to research a high performance photovoltaic grid-connected inverter. This paper mainly researches grid-connected control strategy of single-phase photovoltaic grid-connected inverter, and designs a single-phase photovoltaic grid-connected inverter based on filtering backstepping. The main contents of the paper are as follows:Firstly, on the basis of studying the input power and output control method, and main circuit topology of single-phase photovoltaic grid-connected inverter, the working principle of single-phase full-bridge inverter is analyzed in detail and the mathematical model of the single-phase full-bridge photovoltaic grid-connected inverter is established in the paper. Secondly, a backstepping grid-connected control strategy which is one of the nonlinear control methods is studied. In the study of backstepping’s shortcomings, a single-phase photovoltaic grid connected inverter based on filtering backstepping is proposed, and the simulation model of the system is set up by Matlab/Simulink simulation tool. Meanwhile, the performances of two kinds of grid-connected control schemes are compared in the simulation. Thirdly, a low-power single-phase photovoltaic grid-connected inverter prototype based on filtering backstepping is developed; the design of system hardware circuit principle and parameters calculation method are introduced in detail; the software design method of each module and the program flow chart of the running process are analyzed. Finally, an experimental system of low-power single-phase photovoltaic grid-connected inverter is established; the output waveforms of switch tube driving circuit and the synchronization performance between grid-connected current and network voltage are tested and analyzed.The simulation arid-experiment results show that the filtering backstepping grid-connected control method can achieve good synchronization performance for the single-phase photovoltaic grid-connected inverter. The phase difference between the output grid-connected current of low-power single-phase photovoltaic grid-connected inverter prototype and the network voltage is within 8 degrees. And the harmonics distortion of the grid-connected current meets the national grid-connected standards.