Using the idle dense barn controller, the program was upgraded and the external equipment was matched, so as to realize the automatic control and regulation of temperature and humidity in seedling-raising greenhouse, improve the utilization rate of assets, reduce work and cost, and improve the quality of seedling-raising. The work of tobacco seedling cultivation is the basis of tobacco production. The quality of tobacco seedling cultivation directly affects the later stage of tobacco planting. Because of the tobacco seedling growing process, tobacco seedlings are in the early stage of growth and development, and the requirement of temperature and humidity is very prominent. If the management is not appropriate, the root rot, serious pests and diseases, and dead seedlings of tobacco seedlings will occur.
At present, the daily management of tobacco seedling cultivation is mainly based on manual observation and control. It is difficult to meet the scientific and reasonable requirements of tobacco seedling cultivation because of its high labor intensity, low efficiency and inadequate management.
Therefore, it is necessary to study the automatic control of temperature and humidity in seedling-raising greenhouse. The controller of dense curing barn is manufactured according to document No. 418 of National Tobacco Office (2009). It belongs to the special supporting equipment for tobacco curing. It can be used for tobacco curing from July to September and is stable and reliable. But after the end of Flue-cured tobacco, it is basically idle. In order to save resources, the temperature control of tobacco seedling greenhouse can be applied by upgrading the control program of dense curing barn and equipping some external auxiliary equipment. At present, although some manufacturers produce intelligent tobacco seedling greenhouse, the cost is high, and the greenhouse needs to be reconstructed according to specific requirements. There is no precedent in China to apply the dense curing barn controller to the temperature control of tobacco seedling greenhouse.
In order to realize the precise automatic control of temperature and humidity in tobacco seedling raising, temperature and humidity sensors were placed at several points in the seedling raising shed, and multi-point measurement was realized. At the same time, in order to make full use of the equipment interface of the existing dense barn controller, external equipment such as temperature and humidity sensor and electric film coiler with corresponding interface can be equipped to realize the automatic control of temperature and humidity in seedling-raising greenhouse.
The transparent plastic device made above the sensor can not only avoid sprinkling water on the sensor during seedling raising, but also accept sunlight illumination, so that the temperature measured by the sensor is closer to the temperature in the greenhouse, so as to avoid errors in controlling the temperature in the greenhouse. Intelligent temperature control system of tobacco seedling shed mainly consists of three parts: dense curing barn controller, temperature measurement system and control distribution cabinet. The dense curing barn controller is manufactured according to the relevant standards of the National Tobacco Monopoly Bureau (the company). After upgrading the program software, the dense curing barn controller has two parts: the function module of flue-cured tobacco and the function module of tobacco seedling raising. The dense barn controller is the core of the whole control system, which realizes data acquisition, analysis, processing and issuing control commands. The seedling-raising greenhouse is generally 50 m long and 12 m wide, and its area is relatively large. The temperature measurement system uses DS18B20 to measure the average temperature of five points in the shed, so as to measure the temperature more accurately.
In the process of seedling raising, it is necessary to release the fog in the greenhouse in the morning, so an AM2302B humidity test is added. According to the measured humidity, the fog in the greenhouse of tobacco seedling can be automatically released within a specific time.
The control distribution cabinet is composed of CJX20901 AC contactor, NES-150-24 switching power supply and electric film coiler. The distribution cabinet is equipped with manual/automatic switching switch. When the dense oven controller is used for baking, the temperature of the seedling-raising shed can be controlled manually. The control software is mainly embedded in the single chip computer. The single chip computer selected by the dense barn controller is STC89C516RD , which is a reliable and stable brand. The development environment used is Keil uVision 4 and the development language used is C[3-4], as shown in Figure 1. The parameters of the system need to be set manually. Different parameters can be set according to different time periods. The operation interface is intuitive.
The data area stores temperature and humidity data in real time, compares the data of each time through data analysis, and automatically controls the rise and fall of the electric film coiler. The control software has the following characteristics: real-time dynamic display of the average temperature and humidity of the sensor to facilitate the observation of temperature and timely detection of faults in the seedling-raising greenhouse; the temperature of each point can be checked by key operation, and the temperature situation in the tobacco seedling-raising greenhouse can be grasped in time; the software is divided into flue-cured tobacco module and seedling-raising function module. Key operation into different modules, simple and convenient; hardware has real-time clock function, through software programming to control peripheral equipment in stages; collection and analysis of humidity data in seedling greenhouse, according to the target humidity set by the program, timely discharge of fog in seedling greenhouse. After a tobacco seedling season test, the program of the seedling-raising function module of the dense curing barn controller is stable, easy to operate, more accurate and timely, and has been highly praised by users. The multi-point temperature measurement method is adopted to make the temperature control in the greenhouse more reasonable.
At the same time, because the peripheral film coiler and other equipment are automatically controlled by the dense barn controller according to the manual setting target parameters and the collected temperature and humidity parameters according to certain control rules, the operation is more timely and accurate, and the manual operation trouble is avoided. In the idle baking period, the controller of the dense baking barn is fully utilized, the waste of assets is avoided, and the utilization rate of assets is improved. The seedling-raising period is calculated by 60 days, and the total cost is only 32.8 yuan, if the manual operation requires 0.5 work/day, one worker and 80 yuan per worker, and the external equipment of the greenhouse is automatically controlled by the dense barn controller to automatically adjust the temperature and humidity in the greenhouse, thermostatic element then the electricity consumption per day is 0.96 kW.h/greenhouse, and the unit price of electricity is 0.57 yuan/(kW.h).
It greatly reduces the occupancy of personnel and manpower expenditure. The multi-point temperature measurement method makes the temperature control in the shed more reasonable.
At the same time, the automatic control of equipment makes the adjustment of temperature and humidity more timely and accurate, and greatly reduces the loss caused by manual misoperation and negligence. At present, the research and application of dense curing barn controller in temperature control of tobacco seedling greenhouse has not been reported in China. According to the experimental application effect of dense curing barn controller in temperature control of tobacco seedling greenhouse, the research and application have achieved the desired results. The program of the seedling-raising function module of the dense barn controller runs stably and accurately. The temperature measurement in the greenhouse is reasonable and the adjustment is timely, and good economic and social benefits have been achieved.