PV Power Generation System Modeling And Research Of Grid-tied Control Strategy

At present, the global fossil energy is gradually exhausted, it is urgent to find new energysources. At the same time, the biochemical crisis and environmental pollution caused by fossilfuels has also been a serious threat to human life and production, application of new energy isbecoming a global hot topic. With the advantage of clean and renewable, solar energy win thefavour of people, with more and more extensive application of solar photovoltaic powergeneration system and in the grid-connected power generation, photovoltaic power generationsystem modeling and control technology has become a new hotspot.This thesis focuses on the mathematical model of system, maximum power point trackingcontrol, grid-connection control strategy and the power to tame control four aspects toresearch. First on the basis of mathematical model, through the analysis of the basic circuitprinciple, set up the model of photovoltaic power generation system under the condition ofpartial shading, use the subsection function model with Matlab language implementation,wecan get the characteristics of current present step and power take on the multimodal.Secondly, through the analysis of the various methods used in the maximum power pointtracking control method, this paper proposes a new sliding mode variable structure controlscheme. Based on the Boost converter, through the feedback signal, we can track themaximum power point of the photovoltaic power generation system by controlling theconverter switches. The model is established on the Matlab/simulink platform for simulation,results show that, the controller designed by sliding mode control method can effectivelyimprove the maximum power point tracking speed and stability of steady state, weaken thebuffeting and has strong environment adaptability.At the same time, according to the parameters in other parts, we select the doubleclosed-loop control system that the voltage in outer ring and the current in the inner ring arerespectively used to control.introduce the d-q coordinate transformation to simplify the phasecalculation.The output current of PV system and the voltage of public power grid with thesame frequency and phase through the controller designed by the principle of phase-lockedloop. Calculate the corresponding parameters of the outer voltage loop and inner current loopof control system respectively.Finally, the new energy storage elements are applied to the scheduling of grid connectedphotovoltaic system. Under the integrated control system, we can control the energy flowbetween the power grid and the super capacitor, which can stabilize the fluctuation of powerwhen the grid voltage is too high or too low.