Research On Single-phase Photovoltaic Grid Power Generation System Control Strategy And Phase-locked Loop Technique

In recent years, the words about air quality such as "fog", "PM2.5", "Mask" frequently appear in the public eye, which show that air pollution seriously affects people’s life. Environmental problems are closely related to use of fossil fuels and other non renewable energy. Environmental and energy problems have attracted the attention of the government, and a series of policies to encourage the development of new energy is being gradually implemented. In the field of photovoltaic power generation, the National Development and Reform Commission issued a notice to improve solar photovoltaic power generation internet subsidy price policy, in order to regulate the administration of electricity price of solar photovoltaic, non tender solar photovoltaic power generation project to implement a unified national feed on tariff. Solar energy as a new energy of clean and economy has been hitherto unknown attention.In order to make the conversion of solar energy into electrical energy, the development of photovoltaic power generation is an indispensable link. Aiming at solving the problem of low efficiency of photovoltaic conversion, this thesis is also with the help of the maximum power point control algorithm. This thesis analysis the characteristics of photovoltaic cells, and research on the current mainstream algorithm of the maximum power tracking control. In order to resolve the shortcoming of the MPPT mainstream algorithm in the aspect of good dynamic performance and stability performance, this thesis propose a improved metnod of perturbation and observation method based on fuzzy control, and do the verification of simulation.In order to guarantee the normal work of the inverter and provided grid better quality of electric energy, we must need to design phase synchronous circuit of good performance. In many ways of the phase synchronization, PLL become a kind of conventional phase synchronization technology because of its good synchronization performance. In order to apply the phase-locked loop technology to the grid connected PV system, in this thesis, the current mainstream software phase-locked loop algorithm is studied, and analyze the PLL algorithm is how to implement, and has carried on the verification by the MATLAB simulation software.In order to prove PLL by DSP development platform, we need to apply the proposed theory to DSP development platform, and solve the problem of dc bias. In order to solve the problem of dc bias on PLL, this thesis comes up with the method that is improved minus the dc component method on the basis of comparison and analysis the increase of dc control loop and minus the dc component method both, and this method is more simply and better dynamic performance.Grid connected inverter control strategy is one of the key technologies to realize grid connected power generation. Combined with the inverter current mainstream H6 bridge inverter, LCL filter structure, analysis of the mathematical model and the existing problems, this thesis proposed control strategy based on quasi PR control to achieve the grid connected current.