Research On Photovoltaic Power Generation Grid-connected Control System

With the increasing problems in the shortage of fossil energy and the environmental pollution,it has become an essential trend for the exploration on good-quality and high-efficiency new energies.Among all the available energies,solar energy has the feature of inexhaustible supply,compared with other new energies,it has the unique feature beyond comparison,so that it has been given high attention by the governments of every country.As the main form of solar energy,photovoltaic power generation system has been developed rapidly,so that the research on the photoelectric conversion rate has important practical significance.In this paper,starting from the improvement on the photoelectric conversion rate,it has research on the stability of photovoltaic system and efficiency,and the specific contents are as follows:(1)As to the DC transform in the preceding stage,firstly,it introduces the operating principles of the photovoltaic cell,and by means of the construction of simulated model,it analyzes the relationship between output characteristics and external environment of photovoltaic cell.Then,as to the feature of photovoltaic cell that it is easy to be influenced by external environment,it introduces the MPPT control algorithm,and introduces several classical methods of control algorithm.In terms of traditional algorithm,it puts forward MPPT control algorithm on the integration of constant voltage and long perturbation observation of variable step predicted by the new power,and testifies the validity and superiority by means of the construction of simulated model.(2)As to the control technology of photovoltaic power generation system first of all,it introduces and analyzes the traditional double closed loop control.Next,as to the problem that when the traditional repetitive control is in the grid frequency fluctuation,the grid-connected current can not realize the unsteady-state errorfollow-up control,it puts forward a method which can integrate the PI control with fractional repetitive control,and introduces FIR filter which can cancel the harmonic disturbance when there is fluctuation on the grid voltage frequency.Finally,by means of the construction on stimulated model it has simulation and verification on the control algorithm,which testifies that this control algorithm can not only contain the features of fast and high-efficiency of compound control,but also it can improve the dynamic nature and stability of system,and guarantee the quality of grid-connected electricity.(3)On the basis of theoretical analysis,by means of the design on the software and hardware of photovoltaic power generation system,it constructs an experimental prototype of photovoltaic power generation system,and it adopts TMS320F28335 as the main control chip.By means of the separated experimental analysis on auxiliary circuit and acquisition circuit,it can testify the superiority of these photovoltaic grid-connected system.