Research On 10kW Single-Phase PV Grid-Connected Inverter Systems And Control Technology

Solar energy as a renewable energy is the most promising substitute energy sources. Human can use it as a clean energy directly, and China who is the one of the countries has the most abundant solar energy resources, therefore, for the growing energy crisis today, studying the efficiency of power electronic devices, improving the output characteristics, and development and utilization of solar energy have significant strategic significance. A solar grid-system was designed and built in this paper, and the in-depth study and calculation were elaborated for the maximum power point tracking and inverter drives, system parameters and controller design in this paper.There are some lacks for the traditional architecture of the PV inverter, for example the high cost, poor reliability and hot-spot phenomena. A multi-branch centralized photovoltaic inverter structure was proposed in this paper and pre-boost circuit was used to increase the voltage, which can complete maximum power point tracking of photovoltaic cell. Full-bridge inverter circuit was used in after-class inverter and isolation transformer was used in output stage to achieve electrical isolation, so the input of solar energy and output of standard electricity were achieved which overcame some shortcomings of traditional PV inverter system. In addition, more detailed studies have been done for following areas in this paper:(1) DC/DC circuit topology and controller were designed. The main circuit was combined by super capacitor with boost circuit. The voltage and current of the output side of the polycrystalline silicon solar panel as the control variable to be used, the maximum power as the control objectives, at same time ensuring the boost DC bus voltage at 500V, the technique of variable step disturbance observer is used to achieve maximum power point tracking which improved the utilization of solar energy with maximum extent.(2) High-power DC/AC main circuit topology of grid-connected inverter and its controller were designed. Voltage full-bridge inverter structure was adopted in main DC/AC circuit; the same power IGBT module or single-tube was adopted in IGBT power devices and SPWM control was applied. dsPIC30F5015 chip was adopted in the master controller to complete the design, and the parameters of buffer and filter for output side were calculated in detail. According to a simple principles and robust principles, PID algorithm was adopted to stabilize the DC bus voltage effectively, and regulating the grid power factor; the way of combining passive way with active way was adopted to prevent island effect.A 10kW photovoltaic inverter system was designed in this paper. A small-capacity inverter device was manufactured and large numbers of closed-loop simulation were made. The whole system analysis and simulation results show that the solution is effective in the field of photovoltaic grid, and have practical theory significance and economic significance.