Study Of Single-Phase Grid Inverter Of Solar Photovoltaic Power Generation

With the development and utilization of solar power, photovoltaic power generation grid-connected system is paid more attention with its low running costs and power supply stability. In view of single-phase grid inverter of solar photovoltaic power generation, the technical issues of solar photovoltaic power generation connecting with the grid is studied in the paper.Firstly, according to simulation model of solar cells, the principle of the maximum power point tracking is analysised. Two most commonly used method incremental conductance and disturbance observation is described and the improved disturbance observation based on the two methods is put forward. The Matlab simulation results verify the maximum power point tracking.Secondly, the principles and structure of the inverter circuit is analysised and the main circuit is built on the basis of push-pull DC/DC converter and full bridge DC/AC inverter in the paper. The grid-connected current can track the grid voltage synchronously upon the current tracking methods and the strategy of PI regulation and voltage feedforward control. The Matlab simulation model is set up and the simulation results verify the control strategyThirdly, islanding influences the security of power grid and the PV grid-connected system. The various commonly used active and passive islanding detection method is analysised in the paper. According to the characteristics of this system is proposed, the over/under voltage detection and voltage phase mutation detection method is used to detect islanding. This mothod is analysised and simulation is verified.Finally, the main control circuit of single-phase grid connected inverter system is designed upon TMS320LF2407A. The control circuit includes the minimum system, clock circuit, driver circuit and sampling circuit. The DC/DC and DC/AC circuit control process is introduced and the soft includes the main software program and synchronous interrupt subroutine flow chart and so on. According to the principle of phase-locked of grid-connected system, the digital PLL is built upon TMS320LF2407A and the grid-connected current can real-time track the grid voltage. The system hardware circuit and control strategy is realized.