The method of automatic control of the temperature in the greenhouse

 

(57) Abstract:

Usage: the invention relates to agricultural machinery, and in particular to methods of automatic control of the temperature in the greenhouse. The invention: the invention increases the accuracy of the optimization of temperature and eliminates the need to work at temperatures below permissible. For this additionally determine the age of a plant, the duration of the photoperiod, humidity in the greenhouse, as well as the relative time of the day or night. Specify in accordance with these measurements with optimal productivity, temperature, and optimal consumption temperature compared to the minimum allowable. If the optimum temperature is more valid, then set the optimum temperature, and if the optimum temperature is below limit, then set the allowable temperature. But if the temperature reaches a time limit to the duration of standing, set temperature, optimal productivity. 1 Il. table 1.

The invention relates to agricultural machinery, and in particular to methods of automatic control of the temperature in the greenhouse, more specifically to eniah closed and protected ground. Primarily the invention can be used in plastic film greenhouses, but it can be used when optimizing the temperature in a hangar and block greenhouses.

There is a method of automatic control of temperature in a greenhouse in which to improve efficiency during the whole growing period of plants is divided into equal intervals, the duration of which is at least an order of magnitude smaller than the time constant of the high-speed perturbations. For this period of time is calculated optimal from the condition of equality to zero of the derivative of the economic criterion temperature. In accordance with this change temperature setpoint the setpoint temperature, ensure the maintenance of constant temperature during the selected period of time.

However, the method has great energy and is not very reliable.

There is also known a method of automatic control of the temperature in the greenhouse. In the proposed method, taken as a prototype, rather than estimating the maximum profit uses an estimate of the minimum energy consumption. Instead of the model parameters productivity computing device enter parameters which determine the extremum temperature, at which the extremum is provided, from the condition of equality to zero of the derivative of the specific energy consumption. The setpoint knob to change in accordance with a certain way temperature. The transition from day job temperature at night is performed by changing the coefficients in the model.

The optimum temperature is preceded by the evaluation of the discriminant. If it is negative, the optimal temperature is determined from the conditions of maximum productivity. In addition, examine the conditions under which the temperature naturally installed in a greenhouse without heating, must be less than optimal temperature. If this condition is not met, then the system switches to summer mode, when instead of heating the ventilation works.

However, the method has several disadvantages. First, it does not take into account the age of the plants, the duration of the photoperiod, humidity in the greenhouse. This reduces the accuracy of the determination of the optimal temperature. Secondly, in some cases, determined by the proposed method, the temperature is below the allowable (topt< tSS), and as a result this leads either to the death of plants or to the deterioration of their consumer the Xia long enough. In other words, the restriction must be not only allowable temperature, but also on its duration of standing.

Thirdly, recently obtained a more accurate mathematical model of productivity on the basis of which to obtain accurate expressions for determination of optimum temperature.

For photosynthesis the resulting model

lg A0+A1+E+A2tin+A3T2+A4in+A6+A7with+A11E2+A22t2in+

+A33T22+A44op2+A55in2+A662+A77with2+

+ A12Etin+A13ET2+A14Ein+

+A16E +A17Ec+ A23tinT2+A24tinop+

+A25tinin+A26tin+A27tinwith+A34T2op+

+ A35T2in+A36T2+A37T2with+A45opin+

+A46op+A47opc+A56in+A57inwith+

+ A67withwhere E is the illuminance, CLC;

tinthe temperature in the room,
inthe age of the plants, day.

the humidity of the air in the room,

withthe relative time of day.

A similar pattern is obtained for the intensity of dark respiration D. Only in this model instead of the current light appears average illuminance of the previous day, instead of the average temperature of the previous night, the average temperature of the day, and instead of the relative time of day relative time of night.

The relative time of the day

c= and the relative time of the night

c= current time;

washthe time of sunrise;

Zechthe sunset;

n is the number of crossings 24.00 (0 or 1).

The numerical values of the coefficients in the model for cucumber variety "Moscow" in the table.

The objective of the invention is that it is necessary to increase the accuracy of the optimization of the temperature regime and eliminate work at temperatures less valid.

For this purpose, the method of automatic control of the temperature in the greenhouse, including split period of growing plants at regular intervals, measuring in each of these periods of light flux density of solar radiationi optimal productivity and natural temperature, the comparison of these temperatures and in excess of the first over the second turning on the heating system and maintain it at an optimum temperature on productivity, otherwise the inclusion of the ventilation system, the adjustment of the mathematical model of productivity (photosynthesis or dark respiration) and its coefficients for the transitions "day-night" and "night-day", the definition of the magnitude and sign of the discriminant, which characterizes the existence of a minimum energy consumption and, in case of positivity, determination of the optimal intensity, temperature, and change in accordance with the temperature setpoint knob, additionally determine the age of a plant, the duration of the photoperiod, the humidity in the greenhouse, as well as the relative length of day and night, specify in accordance with these measurements as optimal for productivity and energy intensity temperature, and the optimum temperature is compared with the minimum allowable, and if the optimum temperature is more valid, then set the optimum temperature, and if the optimum temperature is below limit, then set the allowable temperature at the duration of elevation which is istwo for automatic control of temperature and humid regime in the industrial houses which takes into account the age of the birds. However, productivity is influenced not only by age in days, but the time of day, which in existing systems is not taken into account.

In the invention these drawbacks are eliminated, firstly, by the fact that the above-mentioned factors (age of the plants, the duration of the photoperiod, humidity in the greenhouse) are included in the mathematical model and calculating the optimal temperature; secondly, the fact that in the case when the optimal temperature is below limit, the system supports the allowable temperature, and thirdly, the fact that the allowable temperature is maintained for a timeSSand then rises to optimal productivity.

Thus, the inventive method differs in that it uses a more accurate mathematical models of photosynthesis F. and dark respiration D, and, consequently, a more accurate model of the temperature, optimal productivity

topt=

In connection with the specification of the mathematical model of optimal consumption temperature

tOPTA= + where

teat= tn+

D +

< / BR>
tnambient temperature,aboutC;

Q solar radiation flux, W/m2

The device comprises a relay 1 and compare 2 elements, the amplifier 3, the actuator 4, the regulator 5 and the sensor 6 air temperature in the greenhouse, as well as a device 7 for calculation of the optimal consumption temperature.

The device for calculating the optimal consumption temperature includes unit 8 calculates the optimal productivity of temperature, unit 9 calculating ambient temperature, the unit 10 definition of the discriminant, the Comparators 11 and 12, the adder 13, block 14 calculation of the coefficient of heat loss, the switch 15 modes, integrators light 16 and the daily temperature 17, the generator 18 clock pulses, the counter 19 pulses equalization tank light 20 and a day temperature of 21, the device 22 and memory unit 23 of the input data. The device is also equipped with sensors humidity outdoor air 24, solar radiation 25, the light 26, the relay 27 of the light sensors 28 wind speed and ambient temperature 29. In addition, the system includes sensors age (timer) 30 and humidity inside the space 31. The structure of the device for calculating an optimum temperature introduce additional blocks 32 determine litelle standing permissible temperature permissible duration, and the unit 35 for calculating the relative time of the day or night.

The method is as follows.

The vegetation period of plants is divided into equal, pre-computed on duration, intervals. The assumption is made that the length must be an order of magnitude smaller than the time constant of the high-speed perturbations. Then, for each time interval is determined optimum temperature, which in this period should be maintained. After determining the length of time the generator 18 clock pulses (GTI) set in this period.

The generator produces pulses at specified intervals, during which the processing of information received from sensors 6, 24, 25, 26, 28, 29, 30 and 31. The signals from the sensor 26 of the light sensor of age (timer) 30, sensor humidity indoors 31 are received in block 8 of the calculation of the optimal productivity of temperature. This receives the signal from the block define the duration of the photoperiod 32 (which is in turn determined by the timer 30 by fixing the time of sunrise and sunset relay light 27) the ti photoperiod 32). The signals from the humidity sensor outside air 24 and the wind speed sensor 28 is coming to the unit 14 for determining the coefficient of heat loss, the results of which, together with the signals of the sensors solar radiation 25 and the ambient temperature 29 arrive at unit 9 measuring the natural temperature in the greenhouse. The results of calculations and output blocks 8 and 9 come to the comparator 11. If the natural temperature will be more optimal, then automatically turns on the ventilation system, and control system heating and heating are disabled by the relay element 1. If the natural temperature is less than optimal, the result of determining the natural temperature of the block 9 and the signal from the unit 8 calculates the optimal productivity of the temperature arrives at block 10 the definition of the discriminant, where previously entered through block 23 of the input coefficients of the production (from the same block of heat loss calculation 14). From the first output unit 10 a signal is supplied to the comparator 12, and the second output unit 10 and the output unit 9 to the adder 13, compute the optimal consumption temperature. In case of positive discriminant signal for comparing the element 2 of the first Comparators 11 and 12. Thus, for each discrete time interval computing unit 7 determines the optimal temperature. In addition, with the help of block 37, the optimum temperature is compared with the allowable input unit 23. If the optimum temperature would be more valid, then the switch 15 is served at the optimal temperature, if less, then it is permissible. Unit 23 records the duration of standing acceptable temperature and if it is greater than the predetermined (desired issued from block 23), instead of a valid switch 15 is temperature, optimal productivity.

Automatic optimization, consisting of a sensor 6 internal temperature computing unit 7, the comparing element 2, amplifier 3, the actuator 4 and the regulator 5, supports this temperature for a selected period of time, after which the generator 18 clock pulses resets the result of the previous calculation and starts a new one. Clock 18 simultaneously controls the operation of the blocks 13, 8, 9 and 10. The role of clock and timer 30, which significantly reduces the system.

Switching from DNEVNOY device 23 of the input data to the block 10 calculate the discriminant and the unit 8 calculates the optimal productivity of the temperature coefficients of the night model the values which are entered during setup. At the same time to the computing device 8 is connected to the device 22, the receiving signal from the averager 20 light and averager 21 daily temperature during the day period give private from division of the signals from the integrators 16 and 17 on the counter 19 pulses, running from the generator 18 clock pulses and relay 27 of the light.

At the same time from the computing device disconnects the unit 14 to calculate the heat loss from the sensors 24 and 28, and solar radiation sensors 25 and light 26. The sensor 29 ambient temperature connected to a computing device constantly. Switch from night mode to day is similar to.

The proposed method is implemented, for example, a device for calculating an optimum temperature, consisting of the following elements: a Central processor; two permanent storage devices ROM; RAM RAM decoder memory addresses; the address decoder input and output; timer with a quartz oscillator and controls; controls; indicators; device control sensors; termination device.

The volume of programs recorded in the ROM will be 10 Kbytes, RAM 2 Kbytes.

As timer and simultaneously gauge the age used BIS type KVI. Clock frequency, which determines the time specified crystal oscillator.

All the sensors are in the form of independent modules, which are located at appropriate points greenhouses and performs the function of converting controlled environment settings into an electrical signal DC voltage in the range of 0.10 Century

Standalone modules receive power control commands and generates information signals into a single channel of communication and power coaxial cable.

Supply of sensors designed power module sensors, generating a frequency of 20 kHz.

For control modules, sensors proposed controller module operating at a frequency of 250.375 kHz.

As the temperature sensor is used, the resistance thermometer as sensors of indoor air humidity hygrometer design AFI; as the humidity sensor outdoor air system consisting of a dielectric square which was removals combination tachometric device on the bus.St. N 1140047 and optoelectronic on author.St. N 857882.

The sensor arsenide-gallium solar cell, the solar radiation sensor battery Peltier elements.

All sensors are equipped with normalizing converters with operational amplifiers COD or COD.

However, instead of a hardware solution, it is possible to purely software.

An example implementation of the method (optimization of the temperature regime growing cucumber variety "Moscow greenhouse").

a) Let the sensors show the following values of measured value

E=21,1 klk; =80%in=22 days.op15 h; Tn30,5aboutC.

Then the temperature optimal productivity

topt31,1aboutC.

If the environmental parameters

tn-2,5aboutS; V 15 m/s; 80% Q 215 W/m2then the natural temperature in the greenhouse 22,5aboutC.

The discriminant

D + -156,2 Because D < 0, the optimum energy does not exist and the system works when 31,3aboutC.

b) Suppose the humidity At 60% Then

topt13,2aboutWITH

Let then the wind speed is 5 m/s

This natural temperature increases to

teat42,3aboutop9 o'clock Then topt30,6aboutC.

Let tn-27,5aboutS; V 15 m/s; 80% Natural temperature is decreased to teat-2,5aboutC.

D 99,2 > 0. Therefore, tOPTA24,4aboutWith that installed.

As you can see, the optimal intensity of temperature on the 6aboutWith lower than optimal productivity that provides great savings warmth.

C) Let E=10,5 klk; 80% in14 days.op15 h; Tn=19,5aboutWITH

Then topt18,9aboutC.

At tn-27,5aboutS; V=15 m/s; 80% teat=-15,3aboutC.

Since D 117,7 > 0, then tOPTA12,6aboutC.

Since tOPTA< tSS14aboutTo set the temperature of the 14aboutC. If within three days the temperature rises, the system will switch to topt18,9aboutC.

The METHOD of AUTOMATIC control of the TEMPERATURE IN the GREENHOUSE, including split period of growing plants at regular intervals, measuring in each of these periods of light flux density of solar radiation, ambient temperature, wind speed and humidity outside air, the determination of the results of these measure concentration with increasing first over the second turning on the heating system and maintaining its temperature, optimal productivity, otherwise the inclusion of the ventilation system, the adjustment of the mathematical model and its coefficients for transitions of day-night and night-day definition of the algorithm of the process model in the greenhouse the magnitude and sign of the discriminant, which characterizes the existence of a minimum energy consumption, and in the case of a positive determination of the optimal intensity, temperature, and change in accordance with the temperature setpoint knob, characterized in that it further determine the age of a plant, the duration of the photoperiod, humidity in the greenhouse, as well as the relative length of day and night, mentioned the value of a discriminant is determined from the expression

< / BR>
where taboutpttemperature, optimal productivity;

tewithtthe air temperature in the greenhouse, which is installed in the absence of additional heating;

A22the regression coefficient of model efficiency in the square of the temperature in the greenhouse;

and optimal consumption temperature topt.efrom the expression

< / BR>
and accordingly adjust for optimal productivity, temperature, and optimal optymalna temperature greater than the minimum allowed temperature of the air in the greenhouse, then set the optimum temperature, and if the optimum temperature less valid, then specify the allowable temperature, and when it reaches the last specified maximum term of its standing set temperature, optimal productivity.

 

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