SU1576791A1 - Device for automatic centralized control of heat supply system of hothouse complex - Google Patents

Abstract

The invention relates to agriculture and construction and can be used to control elements of district heating networks. The purpose of the invention is to optimize the temperature regime of the greenhouses of the greenhouse complex by taking into account the dynamic characteristics of the network’s pipelines. When the weather factors change, the signal from the weather sensor sensor 6 is damped by the low-pass filter 7, i.e. the high frequency component of this signal is suppressed. The cut-off frequency of the low-pass filter 7 is automatically adjusted depending on the signal from the sensor 8 flow rate of the coolant, since its value, along with the length of the pipeline and the dynamic characteristics of the greenhouse 9 of the greenhouse complex, is determined by the speed of water in the supply pipe. After the low-frequency filter 7 is damped, the signal from the sensor 6 of the meteorological factors arrives at the input of the water temperature controller 4, which accordingly changes the water temperature in the supply pipe 2, which supplies water to the heat supply systems of greenhouses 9 from the source 1. Thus, the controller 4 compensates the effect only the low-frequency component of changes in meteorological factors, eliminating the deterioration of the quality of compensation due to resonance effects, by taking into account the dynamic conditions akteristik pipelines, greenhouses and changes in water velocity in the ducts. 3 il.

Description

(21) 4404256 / 31-15

(22) 04/05/88

(46) 07.07.90. Bul Number 25

(71) Tselinograd Agricultural Institute

(72) L. I. Gurevich

(53) 631.3448 (088.8)

(56) Feershteyn L M., Etingen L. S, Gokhboim G. G. Reference book on automation of boiler rooms. - M .: Energie, 1978, p. 96

(54) DEVICE FOR AUTOMATIC CENTRALIZED CONTROL OF THE HEAT SUPPLY SYSTEM OF THE HEATING PLANT

(57) The invention relates to agriculture and construction and can be used to control elements of district heating networks. The purpose of the invention is to optimize the temperature regime of the greenhouses of the greenhouse complex by taking into account the dynamic characteristics of the network’s pipelines. When the weather factors change, the signal from the weather sensor sensor 6 is damped by the low-pass filter 7, i.e. it is suppressed

high frequency component of this signal. The cut-off frequency of the low-pass filter 7 is automatically adjusted depending on the signal from the sensor 8 of the coolant flow rate, since its value, along with the pipeline length and the dynamic characteristics of the greenhouse 9 of the greenhouse, is determined by the speed of water in the supply line After the damping of the low-pass filter 7, the signal from the sensor 6 meteorological factors are fed to the inlet of the water temperature controller 4, which accordingly changes the temperature of the water in the supply pipe 2. which supplies water to the heat supply systems of greenhouses 9 from source 1. Thus, controller 4 compensates for the effect on the temperature regime of greenhouses 9 of the greenhouse plant only the low frequency component of changes in meteorological factors, excluding the deterioration of compensation due to resonant effects, by taking into account the dynamic characteristics pipelines, greenhouses and changes in water velocity in pipelines 3 or

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FIG. J

cn vi

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The invention relates to agriculture and construction and can be applied in the field of management of elements of district heating networks.

The aim of the invention is to optimize the temperature conditions of the greenhouses of the greenhouse plant by taking into account the dynamic characteristics of the network pipelines.

FIG. 1 shows a functional diagram of the device; in fig. 2 is a graph of the control index of the heat supply system; in fig. 3 - functional scheme of a tunable low-pass filter.

The device contains a heat supply source 1 with a flow 2 and a discharge 3 pipes connected to it, a water temperature controller 4 in the flow 2 pipeline with a temperature sensor 5 connected to it, installed on the flow 2 pipeline, and a meteorological sensor 6, a tunable low-pass filter 7, the input of which is connected to the sensor of 6 meteorological factors, and the output to the controller 4 of the water temperature in the supply 2 pipeline. The water flow sensor 8 is installed on the supply pipe 2 and is connected to the parametric input of a tunable low-pass filter 7. The greenhouses 9 of the greenhouse complex are connected to the feed 2 and discharge 3 pipelines through a thermal unit including control and stabilization parameters of the heat carrier, for example, three A traditional mixing valve 10 with a mixing pump 11 or a throttling valve 12 and regulators 13 connected to the valves with sensors 14 of air temperature in greenhouses 9 of the greenhouse complex.

As a tunable low-pass filter, any low-pass filters with automatically adjusted cutoff frequency can be used in the device. The choice of one or another filter depends on the element base of the automatic control system, since it is expedient to implement the specified filter on the element base of the latter. So when using analog electronic water temperature controllers, it is advisable to use tunable electric RC filters. In the case of the use of a control digital computer, it is advisable to use software-implemented and tunable digital filters in the same machine.

For example, a tunable low-frequency filter of an electromechanical type can be used as a low-pass filter 7, which is most suitable for a given device, since it can operate at such low frequencies that it is difficult to ensure the quality of any other filters.

Infrared-tunable electromechanical filter (Fig. 3), you

five

0

0 0 5

0 0

five

five

complete on the base of the follower controller, contains a series-connected summing element 15, an amplifier 16, a unit 17 for correcting the rotational speed of the engine 18 with a gearbox 19, and two displacement sensors 20 and 21, one of which is connected to the summing element 15, and the signal from the other is the output signal of the filter 7. The transfer function of the low-pass filter 7 is equal to

Utr,} - MvYM-1.Kt (P) -ia, (P) - VPM

t L,

Kl-KjUKOp Kuj- Kt

where P is the Laplace operator; iyu - output voltage; Us is the input voltage; - constant filter time; K - sensitivity of displacement sensor 11;

K2 is the gain of the amplifier; Кз - transmission coefficient of the engine speed correction block 17;

K.45 - the transmission coefficient of the engine 18 with gear 19; KKOR is the voltage controlling the number of revolutions of the engine 18; KB is the sensitivity of the displacement sensor 20.

Thus, the transfer function of the servo regulator corresponds to the transfer function of the aperiodic link of the first order, i.e., the low frequency filter of the first order.

In this case, the time constant of the filter Tt can be roughly adjusted by changing the gear ratio of the gearbox 19, and smoothly by changing the voltage UKOP from the flow sensor 8 (Fig. 1).

For the implementation of filter 7, for example, power amplifiers with reversible asynchronous motor from any self-recording bridge or potentiometer can be used, any potentiometers can be used as displacement sensors 20 and 21, and a magnetic amplifier as a speed correction unit 17.

The expediency of using a tunable filter 7 is justified by the fact that in its absence, the controllability index of the system Iq (jco) J (Fig. 2) becomes greater than one for frequencies large about (for quality control) and large (for quantitative control). At the frequencies indicated above, it is impractical to centrally control the heat supply, since, due to the dynamic characteristics of the heat supply system and greenhouses, the control effect comes in antiphase, thereby increasing the regulation error, even compared to the regulation error without a controller at all.

However, some of the information about the disturbing effects of the controller 4 is lost due to the filter 7, but using this information only impairs the operation of the heat management system. Thus, controller 4 compensates for the effect on the temperature regime of greenhouses only the low-frequency component of the disturbing effects of weather factors, the high-frequency component (high frequency component of changes in natural light, wind speed) is compensated for by local controllers 13.

The device works as follows.

With unchanged meteorological factors, the water temperature controller 4 in accordance with the sensor signal of the meteorological factors, influences the actuators of the heat supply source 1, maintains the required water temperature in the supply pipe 2, corresponding to the heat sink of the greenhouse 9 of the greenhouse complex and allowing the regulators 13 to be in in the middle of the working range and, therefore, be ready to work out the technological transitions associated with the transition from one level of stabilization of the air temperature in the greenhouse 9 to d nother

When the meteorological factors change, the signal from the meteorological sensor 6 is damped by the low-frequency filter 7 (in the simplest case, the filter 7 is an aperiodic element of the first order with a variable constant time), i.e. the high-frequency component of this signal is suppressed.

The cut-off frequency of the low-pass filter 7 is automatically adjusted depending on the signal from the flow sensor 8, since its value, along with the pipeline length and the dynamic characteristics of the greenhouse, is determined by the speed of water in the supply pipe 2, which uniquely depends on the position of the valve plungers 10 or 12, which depends on many factors, including on the set air temperature in the greenhouse 9, on meteorological factors, etc. After damping with low-pass filter 7, the signal from sensor 6 of meteorological factors is post falls to the input of the regulator 4, which changes the water temperature in the supply pipe 2 accordingly. Thus, the controller 4 compensates the effect on the temperature regime of the greenhouses 9 of the greenhouse plant only the low-frequency component of the changes in meteorological factors (Fig. 1), excluding deterioration quality compensation due to resonant phenomena, by taking into account the dynamic characteristics of pipelines, greenhouses

 and changes in water velocity in pipelines.

The device allows to improve the accuracy of stabilization of the temperature regime of the greenhouses of the greenhouse complex by accounting for

5 centralized management of heat supply dynamic characteristics of the pipeline and greenhouses.

Claims (1)

Invention Formula 0 Device for automatic centralized control of the heat supply system of a greenhouse complex, containing a heat supply source, supply and exhaust piping connected to it, heat carrier temperature controller in the supply pipe, the first input of which is connected to the heat carrier temperature sensor in the flow pipe, sensor of weather factors, systems heat consumption of greenhouses of the greenhouse complex, 0 connected to the supply and discharge pipelines through a thermal node, including the elements of regulating and stabilizing the parameters of the coolant, equipped with controllers with air temperature sensors in greenhouses, characterized in that 5 in order to optimize the temperature conditions of the greenhouses of the greenhouse complex by taking into account the dynamic characteristics of the network’s pipelines, it is equipped with a tunable low-frequency filter, the input of which is connected to the sensor of meteorological factors, and the output is connected to the second output of the heat carrier temperature controller in the supply pipeline, and the flow sensor of the heat carrier installed on a supply pipe, the output of which is connected to the parametric input of a tunable low-pass filter. 0 10 1-Ю 11 НОО (1) 2-Ю 3и), 7 / С FIG. 2 at 1e Fig.z