Research On Concentrating Model And Optimal Scheduling System Of Heliostat

Tower solar thermal power generation technology has a very broad development prospect because of its advantages such as large concentrating ratio,high system efficiency and good power quality,which quickly stand out among many solar power generation technologies.Heliostat and heat absorber,as the two core components of the concentrating heat collector subsystem of tower solar thermal power station,the main function is that the heliostat focuses the reflection of the sun’s rays to the surface of the heat absorber,forms a heat flow distribution on the surface of the heat absorber,and heats the working medium inside the heat absorber,thereby generating steam to drive the generator to generate electricity.During the focusing process,it is easily affected by weather and other interference factors,resulting in uneven heat flow distribution on the surface of the heat absorber,which will have a great impact on the safety and efficiency of the heat absorber,thus affecting the stable operation efficiency of the whole power station.In this study,we take the national solar thermal demonstration project China Energy Construction Hami molten salt tower solar thermal power station as the research object,and propose a reasonable and effective heat absorber focus optimization scheduling model and strategy,the main work is as follows:(1)The heat flow distribution on the surface of the heat absorber is formed by the convergence of thousands of reflected spots of heliostats.Therefore,it is first necessary to study the entire process of reflected spot formation from the single-sided heliostat.Consider the non-parallel lightness of sunlight,combined with various influencing factors of the heliostat in the process of light gathering,such as cosine effect,atmospheric transmittance,etc.The Gaussian distribution method based on the HFLCAL model is used to establish the heliostat concentrating model,simulate the spot imaging of the single-sided heliostat,and finally obtain the heat flux density distribution of the entire mirror field on the surface of the heat absorber,which meets the requirements of accuracy and speed.(2)Based on the concentrating model and finite element software,an experimental simulation platform is established to analyze the influence of the flow and heat transfer process of molten salt in the heat absorber tube on the heat flow distribution on the heat absorber surface.The physical model of the tube panel of the heat absorber is established,and the calculation model of the molten salt flow and heat transfer process in the heat absorber tube is established.On this basis,experiments are carried out with the concentrator model as the boundary heat source,and the result of reducing the two-dimensional scheduling problem in the scheduling optimization system to a one-dimensional horizontal scheduling problem is obtained,which reduces the complexity of the scheduling system.(3)In order to solve the problem of uneven heat flow distribution caused by interference factors,a multi-focus point method is proposed,and a two-objective optimization function of minimum heat spillage rate and minimum heat flux density standard deviation is established from the aspects of safety and efficiency.For the optimization strategy,according to different interference factors,the whole optimization system is divided into two modes:periodic optimization and random optimization,and the improved genetic algorithm is selected to solve the periodic optimization mode,and the BP neural network is selected to solve the random optimization mode,and the optimization system can meet the safe and efficient working requirements of the heat sink through experimental simulation results.So as to ensure the stable operation of the entire power station.