| Photovoltaic greenhouse is a new type of facility structure which uses photovoltaic cells to provide greenhouse energy.At present,the development of photovoltaic agriculture is strongly supported by the state,but the influence of solar energy resources,climate and other factors leads to great differences in the development of photovoltaic agriculture in different regions,while Chongqing has a good potential for solar energy application due to long sunshine and high temperature in summer.In facility production,light quality seriously affects the yield and quality of vegetable crops.In the plant growth cycle,LED light source with different light quality is used to control the growth quality of plants under different light quality,so as to obtain the best light quality conditions for plant growth and development.Therefore,how to make full use of the solar energy resources in Chongqing in summer,solve the problem of greenhouse cooling and energy saving,and explore the impact of different light quality LED light sources on plant quality is of great significance to promote the development of facility agriculture in Chongqing.On the basis of consulting domestic and foreign literature,this paper designs a simulated greenhouse system with photovoltaic city electricity complementary system,environmental monitoring system,water curtain cooling device,water fertilizer management device,and studies the influence of different light quality LED light sources on lettuce quality under the same management mode.The main work of this paper is as follows:(1)Photovoltaic city power complementary system design.Photovoltaic city power complementary system is composed of photovoltaic cells,solar controller,battery pack,inverter,double pole double relay and automatic switching device.It mainly realizes the function of automatic switching to the city power supply when the energy supply of photovoltaic cells is not enough to support the energy required by the simulated greenhouse in summer,so as to provide the necessary environmental conditions for the growth of greenhouse plants continuously.A mathematical model is established to evaluate the economic benefits of the operation of the combined power supply system.(2)The design of greenhouse water fertilizer light management system.At the water fertilizer end,a pressure type flow sensor is used to collect the flow of individual pipes outside each box to ensure the same flow management.The soil moisture in the box is detected and fed back to the controller end to control the start and stop of the water pump and the independent on-off of the solenoid valve.At the light end,the light intensity sensor is used to detect the light intensity in real time and feed it back to the controller,and the light intensity is displayed on the controller screen.(3)The hardware circuit design and control program writing of the box control end.STM32F103C8T6 singlechip microcomputer is used as the control core of the control terminal equipment,and the communication between the modules is realized by IIC bus and single bus.Both water fertilizer management and greenhouse cooling in summer are designed with automatic and manual dual control modes.(4)Experimental design of orthogonal optimization for energy saving and cooling of water curtain in summer.Taking the thickness of water curtain,wind speed of water curtain fan and flow of water curtain pump as three factors,the power loss(kW·h)and water consumption(m3)as reference indexes,the orthogonal test is designed.The results show that the thickness of water curtain is 20cm,the wind speed of water curtain passing through the curtain is 8m/s,and the flow of water curtain pump is 115cm3/s,which is the best combination of cooling in summer.(5)The effect of LED on the growth and quality of lettuce.The effects of different LED light quality on the chlorophyll,fresh weight,plant height and leaf number of lettuce were studied by using white light(W),blue light(B),red light(R),yellow light(Y),red blue light 3:1(RB)with a flux density of 250 ? mol·m-2·S-1 as the experimental group.The results showed that the growth of lettuce plants was inhibited by monochromatic yellow light from the 10th day;the fresh weight and leaf area of lettuce plants were the largest under red blue combined light;the plant height and leaf number were the highest under monochromatic red light;the chlorophyll content of lettuce plants was the highest under full spectrum white light.According to factor analysis,the numerical order of quality comprehensive score is RB>R>B>W>CK.Under the same environmental conditions,water and fertilizer management and energy consumption conditions,the highest comprehensive quality score was the combination of red and blue light,which was 90.17%higher than sunlight,30.83%higher than monochromatic red light,41.27%higher than monochromatic blue light,and 42.07%higher than full spectrum white light. |
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