Research Of Single-phase Photovoltaic Grid Control Based On DSP

With the rapid development of global economy,the consumption of non-renewable energy created today’s energy shortage, along with the growing energy crisis.Human beings must strive to find the sustainable development of new energy,which is a renewable and pollution-free energy,and solar power new technology are now presented by experts and began to be applied. In today’s society,many countries in the world are very attention to the development of photovoltaic power generation technology,and our government has also introduced many relevant policies to encourage the development of domestic PV industry. Therefore under the background of times,this paper based on the single-phase photovoltaic grid system as the research object,carrying on the detailed introduction and comprehensive analysis,and from the topological structure of photovoltaic grid system,the principle of photovoltaic array,maximum power tracking,control strategy,and phase-locking and islanding such aspects as did the analysis and simulation.Main work is as follows:According to the actual circumstance of engineering,this paper established the mathematical model of the photovoltaic cells,and simulation model is set up by the MATLAB/Simulink,then output characteristic of photovoltaic battery is analyzed through the simulation.Results show that the model is correct and as a foundation for the follow-up study.This paper adopts the method of constant voltage and disturbance observation method for MPPT,and the simulation model of constant voltage method, the disturbance observation method and conductance increment method was respectively builded in Simulink and simulated.Results show that both conductance increment method and perturbation observation method can accurately track the maximum power point, and constant voltage tracking speed is fast but accuracy is not high.This paper uses a modified triangle wave comparison control method,and the simulation model of the triangular wave comparison, the triangular wave comparison method with feed-forward and the modified triangle wave comparison of the simulation was respectively builded in Simulink and simulation.The results show that harmonic of the modified was smaller,and waveform was high quality.Phase-locked technology based on synchronous rotating coordinates was adopted,the method is different from previous zero.Changing the sampling voltage amplitude and injecting three times harmonic two situations were simulated respectively in simulink, the results show that the method makes the grid current good tracing the change of the power grid, and has strong anti-jamming capability, good stability.Adopting the improved active frequency drift method on the island, which was simulated by writing S function in Simulink,the results show that this method can more quickly the islanding detection.Finally, the hardware circuit of the specific parameters for the calculation analysis and choice, simply introduces the principle of DSP2812and how the SPWM in DSP implementation.