CN113587414B - Air conditioner water system control system - Google Patents

Air conditioner water system control system Download PDF

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CN113587414B
CN113587414B CN202110933986.8A CN202110933986A CN113587414B CN 113587414 B CN113587414 B CN 113587414B CN 202110933986 A CN202110933986 A CN 202110933986A CN 113587414 B CN113587414 B CN 113587414B
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李楠
冯松松
周俊
谢李杰
蒋梦奇
李昕桐
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Chongqing University
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
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Abstract

The invention discloses an air conditioner water system control system, which is characterized by comprising the following components: a terminal load predictor connected with an outdoor data detection instrument outside a room where the terminal of each air conditioner is located; the terminal equipment instantaneous required flow calculation module is used for acquiring the maximum supply and return water temperature difference of the safe and stable operation of each air conditioner terminal equipment; a control pressure difference generator with one end connected to the instantaneous flow calculating module and the other end connected to the water pump controller; and the water pump controller is connected with a secondary pump in the power unit of the air-conditioning water system and can perform PID control on the number and the frequency of the water pumps of the secondary pump according to the actual water supply and return pressure difference acquired in real time and the deviation of a set value of the control pressure difference. The invention can more accurately meet the end requirement and has the advantages of simple, accurate, safe and stable control.

Description

Air conditioner water system control system
The application is a divisional application of a patent of an AI-based air conditioner variable flow water system self-adaptive variable pressure difference control method, which is filed under the application number of 202011137597.6 and the application date of 2020-10-22.
Technical Field
The invention relates to the field of heating ventilation air conditioner automatic control, in particular to an air conditioner water system control system.
Background
In a central heating and ventilation air conditioner of a building, an air conditioning water system is generally adopted to convey cold and heat so as to supply cold and heat indoors. Along with the development of social economy and the improvement of the living standard of people, the building energy consumption is higher and higher. In the energy consumption of buildings in China, the energy consumption of the heating, ventilating and air conditioning accounts for a large proportion, and accounts for about 30-50%. 35% -45% of the energy consumption of the air conditioner is consumed by a fan water pump in an air conditioner water system, and more than 40% of the energy consumption is consumed by various regulating valves, so that the research on the energy-saving control technology of the air conditioner water system is significant.
The main control technology of the existing air-conditioning water system is a stable constant pressure difference control technology, which is to set a fixed water supply and return water pressure difference set value of the water system, and control the number and frequency of water pumps according to the deviation of the actual water supply and return water pressure difference and the set value, thereby realizing the function of flow regulation. However, there are still many problems in terms of operational effect and energy saving:
a. the set value of the constant differential pressure control differential pressure is designed according to the maximum load requirement, and the air conditioner is in a partial load working condition most of the time, so the set value is often overlarge, the opening degree of a valve at the tail end of the air conditioner has to be reduced to offset redundant pressure heads, and unnecessary energy consumption waste is caused.
b. If the tail end equipment is lack of an effective flow regulating device, the pressure difference set value for controlling the variable frequency water pump is too large, and the phenomena of large flow and small temperature difference are easily caused. Not only the transmission and distribution energy consumption is increased, but also the working state of small temperature difference leads to the low evaporation temperature of the cold source and reduces the energy efficiency of the cold source.
c. The chilled water system is a secondary pump system, the large flow rate of the secondary side causes return water to directly flow to supply water through the bypass pipe and be mixed with the supply water, the supply water temperature is influenced, the tail end requirement cannot be met, and the heat exchange efficiency of the tail end is reduced.
Because the air-conditioning water system is a closed system, the pressure and the flow rate of the air-conditioning water system satisfy the formula (1); the instantaneous cooling and heating load satisfies the formula (2). Equation (3) is a conversion equation of the water volume flow and the mass flow.
ΔP＝SL2 (1)
Q＝cmΔt (2)
m＝ρL (3).
In the formula: delta P is the pressure difference of water supply and return in Pa; s is the impedance of the pipe network in kg/m7(ii) a L is the volume flow of water, in m3S; q is cold and heat load, unit kW; c is the specific heat of water, typically taken at 4.2 kJ/(. degree.C. kg); m is the mass flow of water, unit kg/s; delta t is the temperature difference of supply and return water, unit ℃; rho is the density of water and is generally 1000kg/m3。
According to the formulas (1), (2) and (3), the relation between the pressure difference of the water supply and the water return of the main pipe and the instantaneous load can be obtained, see the formula (4). Because the load is constantly changed, the pressure difference of the water supply and return setting should be constantly changed so as to be better matched with the load.
Figure BDA0003209625470000021
The meaning and the unit of the letter parameter of the formula (4) are the same as those of the formulas (1), (2) and (3).
Therefore, the variable pressure difference control technology is researched, a proper pressure difference value is set according to the condition at each moment, the phenomena of large flow, small temperature difference and bypass reverse flow of a water system with terminal equipment lacking an effective flow adjusting device can be effectively improved, the water supply temperature is optimized, the terminal heat exchange efficiency is improved, the transmission and distribution energy consumption is effectively reduced, and the energy is saved. Is the technical development direction of air-conditioning water system control. Partial variable differential pressure control technology exists in the prior art, but the respective defects still exist.
Patent CN102748802B "variable pressure difference energy-saving device of circulating pump", granted on 24.6.2015, tests outdoor temperature through a temperature sensor, and the set value of the pressure difference of supply and return water changes with the outdoor temperature. It can be seen from the formula (4) that the set pressure difference value is influenced by the impedance of the pipe network and the cold and hot loads, the impedance of the pipe network is mainly related to the operation conditions of different terminals, and the cold and hot loads are influenced by multiple factors such as outdoor temperature, humidity, solar radiation intensity, personnel density and the like, so that the set pressure difference value is judged by only the outdoor temperature to be inaccurate, and terminal underflow is easily caused.
Patent CN1186572C entitled "variable pressure difference and variable flow control method and system for air conditioning water system" in 2005, 1 month and 26 days measures process flow Qi and formula delta P in real timei＝A(Qi/Qs)2And+ B, obtaining a real-time pressure difference set value, and controlling the chilled water system in real time. Its real formula Δ Pi＝A(Qi/Qs)2+ B is given according to equation (1) and assuming constant pipe network impedance. In the actual operation process, the operation conditions of the tail ends are different, so that the impedance S is not a constant value. This method can cause the pressure difference set value to be inaccurate and cannot meet the cold and hot requirements of users.
Patent CN107588500A entitled adaptive variable pressure difference and variable flow rate regulation and control method for heating system disclosed in 1/6/2018 calculates temperature difference between supply water and return water according to tested outdoor temperature, collects average temperature value of actual supply water and return water of heating network by temperature sensor according to average temperature value of supply water and return water, calculates average temperature and compares with actual average temperature, and outputs calculated pressure difference value required by heating network by integral of comparison error. The pressure difference value is determined by the load and the hydraulic and thermal running conditions of a pipe network, and the method only considers simple outdoor temperature and has the phenomenon of inaccurate control. And the temperature signal is delayed, so the acquired average temperature value of the actual supply and return water of the heat supply pipe network is questioned.
The utility model patent CN203869259U entitled "a pressure difference control device based on terminal air conditioning equipment chilled water valve aperture" granted 10/8/2014 carries out pressure difference adjustment according to the terminal maximum valve aperture, but it must require all the terminals to install the electric valves with the same flow characteristics, and all the valve aperture signals can be collected. Because the valve opening signal has certain delay and is easy to fluctuate, inaccurate control is easy to cause, and the pressure difference set value vibrates.
Therefore, the problems of tail end undercurrent, complex control and the like caused by inaccurate control of the existing researched variable differential pressure control are not popularized yet. Therefore, how to achieve energy saving as much as possible on the basis of better ensuring the energy consumption requirements of all the tail ends, and the control mode is simpler, more accurate, more stable and more reliable, becomes a problem to be solved by technical personnel in the field.
Disclosure of Invention
Aiming at the defects of the prior art, the technical problems to be solved by the invention are as follows: the air conditioner water system control system can more accurately meet the end requirements and is simple, accurate, safe and stable to control.
In order to solve the technical problems, the invention adopts the following technical scheme:
the invention is realized by adopting the following air-conditioning water system control system, and the air-conditioning water system control system comprises:
the terminal load predictor is connected with an outdoor data detection instrument outside a room where the tail end of each air conditioner is located, the outdoor data detection instrument comprises but is not limited to an outdoor air temperature detector, an outdoor air humidity detector, a solar radiation intensity detector and a wind speed detector, a terminal load prediction model is arranged in the terminal load predictor, and the terminal load prediction model can collect outdoor air temperature, outdoor air humidity, outdoor solar radiation intensity and outdoor wind speed outside the room where the tail end of each air conditioner is located and predict each terminal load;
the system comprises a terminal equipment instantaneous required flow calculation module, a terminal equipment instantaneous required flow calculation module and a control module, wherein the terminal equipment instantaneous required flow calculation module can acquire the maximum supply and return water temperature difference of safe and stable operation of each air conditioner terminal equipment; the terminal equipment instantaneous required flow calculation module is used for calculating the instantaneous required flow of each air conditioner terminal equipment according to the predicted value of each air conditioner terminal load and the maximum water supply and return temperature difference of each air conditioner terminal safe and stable operation;
the control pressure difference generator is internally preset with a control pressure difference value-corresponding database of each tail end flow, a plurality of corresponding control pressure difference values can be matched according to the instantaneous required flow of each air conditioner tail end device, and the control pressure difference value with the maximum value is selected as a control pressure difference set value for real-time control to control the water pump controller;
the water pump controller is connected with a secondary pump in the air-conditioning water system power unit, the water pump controller is simultaneously connected with a water supply pressure sensor and a water return pressure sensor which are respectively arranged at the water inlet end and the water outlet end of the air-conditioning water system power unit and used for obtaining actual water supply and return pressure difference, and the water pump controller can carry out PID control on the number and the frequency of the water pumps of the secondary pump according to the actual water supply and return pressure difference acquired in real time and the deviation of a set value of the control pressure difference.
Therefore, when the system is used, the prediction of each tail end load can be realized by a tail end load prediction model according to parameters such as outdoor air temperature, outdoor air humidity, outdoor solar radiation intensity, outdoor wind speed and the like outside a room where the tail end of the air conditioner is located, which are detected in real time, and then the instantaneous required flow of each air conditioner tail end device is calculated by a tail end device instantaneous required flow calculation module according to the predicted value of each air conditioner tail end load and the maximum water supply and return temperature difference of each air conditioner tail end during safe and stable operation; and then the control pressure difference value with the maximum value matched by the control pressure difference generator is used as a control pressure difference set value to realize real-time control. The number and frequency of secondary pumps are controlled by a water pump controller, and the actual water supply and return pressure difference is adjusted to be close to a set value of the control pressure difference, so that the variable pressure difference control of the air-conditioning water system can be realized. The device has the characteristics of simple structure, accurate control, contribution to integration and implementation and the like.
And as optimization, the terminal load prediction model adopts an artificial intelligence algorithm, the artificial intelligence algorithm is trained by using the outdoor air temperature, the outdoor air humidity, the outdoor solar radiation intensity and the outdoor wind speed outside the room where the tail end of the air conditioner is positioned as input end parameters and using the actual operation load of the tail end of the air conditioner corresponding to each group of input end parameters as output end parameters to obtain the terminal load prediction model. The artificial intelligence algorithm can adopt artificial neural network, Bayes, decision tree, etc., and the specific algorithm and training process are prior art, so they are not described in detail here.
Therefore, the artificial intelligence algorithm is adopted, the prediction precision of the terminal load can be greatly improved, and the accurate prediction of the terminal load is realized.
Preferably, the terminal load predictor is simultaneously connected with the flow sensor in the branch where each air conditioner terminal device is located, the water inlet end temperature sensor and the water outlet end temperature sensor of each air conditioner terminal device, historical data of outdoor air temperature, outdoor air humidity, outdoor solar radiation intensity and outdoor wind speed in the artificial intelligence algorithm training process are acquired by the outdoor air temperature detector, the outdoor air humidity detector, the solar radiation intensity detector and the wind speed detector at time intervals in advance, and the corresponding actual operation load of each air conditioner terminal is acquired by the flow sensor in the branch where the terminal device is located, and the data acquired by the water inlet end temperature sensor and the water outlet end temperature sensor of each air conditioner terminal device.
In this way, the accuracy of obtaining the prediction model can be better ensured.
And as optimization, the terminal load predictor is also provided with a load day type distinguishing unit which can distinguish date types, classify dates according to different working days and holidays and serve as one of input end parameters of the terminal load prediction model artificial intelligence algorithm.
In this way, the actual operating loads of the air conditioner terminals corresponding to the same outdoor environment parameters are greatly changed due to different working days and holidays, different personnel densities and different lighting and equipment utilization rates. Therefore, the load day type is introduced into the terminal load prediction model as a parameter factor for judgment so as to distinguish the influence of different working days and holidays on the terminal load. This greatly improves the accuracy of the end load prediction. In specific implementation, clustering analysis can be performed according to the historical daily load curve to obtain classification rules of different working days and holidays. And according to the relative size of the daily load of each type of load, a fixed value can be given to each type of load in the interval range of (0,1) and used as an input parameter.
Alternatively, the instantaneous required flow calculation module of the end equipment is connected with the water inlet end temperature sensor and the water outlet end temperature sensor of each air conditioner end equipment, and the historical maximum value of the actual supply and return water temperature difference under the safe and stable operation of each air conditioner end equipment is detected and obtained and is used as the maximum supply and return water temperature difference of the safe and stable operation of each air conditioner end equipment.
This makes the calculation more accurate and reliable.
Alternatively, the instantaneous required flow calculation module of the end equipment obtains a supply and return water temperature difference design value according to the design parameters of each end equipment to be used as the maximum supply and return water temperature difference of the safe and stable operation of each air conditioner end equipment.
Thus, the method is simpler, more convenient and faster.
The terminal equipment instantaneous required flow calculation module is used for calculating the instantaneous required flow of each air conditioner terminal equipment according to the predicted value of each air conditioner terminal load and the maximum water supply and return temperature difference of each air conditioner terminal safe and stable operation; specifically, the calculation is performed according to formula (5).
Li＝Qi/cρΔtmaxi (5)
In the formula, LiThe instantaneous required flow rate of the tail end i is m 3/h; qiLoad prediction value of terminal i, unit W; Δ tmaxiThe maximum temperature difference of the supply water and the return water of the safe and stable operation of the tail end i is obtained according to design data or operation conditions. i is a natural number and indicates the ith end. The remaining characters have the same meanings as in formulas 1 to 4.
The corresponding database of the control pressure difference value-each tail end flow preset in the control pressure difference generator is used for optimization, the control pressure difference value-each tail end flow corresponding database is formed by changing the control pressure difference set value of the control water pump under the condition that all tail end valves are fully opened, and recording the chilled water flow of each tail end device under different control pressure difference set values.
Therefore, the obtained control pressure difference can be ensured to meet the requirements of all terminal equipment to the maximum extent, and the phenomenon of terminal underflow can not be generated. This is because, when all the end valves are fully opened, the end flows are the minimum flows of the end valves under the control pressure difference in the fully opened state, that is, under a certain control pressure difference value, the maximum flow that each end device can obtain by itself is necessarily greater than the end flow corresponding to the control pressure difference value in the database, that is, the requirements of all the end energy consumption can be completely met, and no end energy consumption can be producedEnd underflow phenomenon occurs. The principle is as follows: the tail end of the air conditioner is a parallel pipeline, and the relation between the flow and the pump lift can be expressed by a formula (6). Under a certain pressure difference set value, namely H is a fixed value, in actual operation, the opening degree of all tail end valves cannot be fully opened, so that compared with the condition that the tail end valves of a database are fully opened, the total impedance of a pipe network is increased, and the total flow L is increasedZAnd decreases. And because of the impedance S of the main pipegFor a fixed value, the maximum flow L that can be obtained at the end imaxiI.e. the flow at the end i when the valve is fully open (Si is unchanged), must be greater than the flow at the end i at this differential pressure setting in the database. Then according to the calculated flow L required by each tail endiAnd all tail end valves are controlled by pressure difference values-each tail end flow database when fully opened, and the control pressure difference value delta P for ensuring the normal operation of each tail end is obtainediChoosing the maximum Δ PiThe pressure difference is used as the control pressure difference of the variable frequency water pump. Therefore, the maximum Δ P can be found by the above stepsiThe energy consumption requirements of all the tail ends can be ensured, and the tail end undercurrent phenomenon can not be generated.
Figure BDA0003209625470000061
In the formula, H is the pump head, SgIs the main pipe impedance; l iszThe total flow of the pipe network; siImpedance of a branch pipe network where the tail end i is located; l isiThe flow at the end i. The remaining characters have the same meanings as in formulas 1 to 5.
And as optimization, the terminal load predictor, the terminal equipment instantaneous required flow calculation module and the control pressure difference generator are integrated in the same computer. Therefore, the required hardware equipment is simpler and is beneficial to implementation.
Therefore, the invention has the following advantages: (1) the invention adopts the artificial intelligence algorithm to predict the load of each terminal device, so that the prediction result is more accurate and reliable, and the control accuracy is better improved. (2) Compared with a constant pressure difference control technology, the invention can effectively improve the phenomena of large flow, small temperature difference and bypass countercurrent of a chilled water system with the tail end lacking flow control equipment, not only optimizes the water supply temperature and improves the heat exchange efficiency of the tail end, but also effectively reduces the energy consumption of transmission and distribution and saves the energy. (3) Compared with a constant differential pressure control technology, the invention increases the opening of the valve at the tail end and reduces the waste of the valve on the transmission and distribution energy consumption. (4) The invention saves energy as much as possible on the basis of meeting the requirements of all tail end flows. Therefore, the method of the patent can not cause the phenomenon of end underflow. Compared with other variable pressure difference methods, the method ensures the safety and stability of energy supply, is simple and accurate to control, and is easy to realize.
Drawings
FIG. 1 is a schematic diagram of an air conditioning system control system in accordance with an embodiment.
Fig. 2 is a schematic diagram of an end load predictor.
FIG. 3 is a schematic diagram of a control pressure differential generator.
Fig. 4 is a schematic diagram of the control principle of the water pump controller.
Detailed Description
The present invention will be described in further detail with reference to specific embodiments.
In the specific implementation: referring to fig. 1 to 4, an adaptive variable differential pressure control method for an AI-based air conditioner variable flow water system includes the following steps: a, forecasting the load of each terminal device in real time by using an AI technology to obtain a real-time forecasting value of each terminal load; b, obtaining the maximum supply and return water temperature difference of safe and stable operation of each terminal device according to the operation historical data and design parameters of each terminal device, and calculating to obtain the instantaneous required flow of each terminal device according to the predicted value of each terminal load; c, substituting the instantaneous required flow of each terminal device into a corresponding database of the pre-measured control differential pressure values-each terminal flow to obtain a plurality of control differential pressure values corresponding to different terminal device flows, and selecting the control differential pressure value with the maximum value as the control differential pressure value for real-time control; and d, controlling the (variable frequency) water pump controller according to the control pressure difference value for real-time control and the supply and return water pressure difference value acquired in real time, so that the supply and return water pressure difference value acquired in real time is close to the control pressure difference value.
Therefore, the method has the characteristics of simple control, safety and reliability.
In the step c, the pre-measured control pressure difference value-each terminal flow corresponding database is formed by changing the control pressure difference set value of the variable frequency water pump for control under the condition that all terminal valves are fully opened, recording the chilled water flow of each terminal device under different control pressure difference set values, and forming the control pressure difference value-each terminal flow corresponding database.
Therefore, the obtained control pressure difference can be ensured to meet the requirements of all terminal equipment to the maximum extent, and the phenomenon of terminal underflow can not be generated. The specific principles are explained later when the device is introduced.
And a, training a prediction model obtained by an artificial intelligence algorithm according to historical data in the step a, and realizing prediction of real-time load of each terminal device.
Therefore, the accuracy and reliability of the prediction precision can be better ensured. The specific process is set forth in the description of the apparatus below.
In this embodiment, the present invention is implemented by using the following air conditioning water system control system, referring to fig. 1, which includes:
the terminal load predictor 1 is characterized in that a signal acquisition end of the terminal load predictor 1 is connected with an outdoor data detection instrument outside a room where each air conditioner terminal is located, the outdoor data detection instrument comprises but is not limited to an outdoor air temperature detector 2, an outdoor air humidity detector 3, a solar radiation intensity detector 4 and an air speed detector 5, a terminal load prediction model is arranged in the terminal load predictor 1, and the terminal load prediction model can acquire the outdoor air temperature, the outdoor air humidity, the outdoor solar radiation intensity and the outdoor air speed outside the room where each air conditioner terminal is located and predict each terminal load;
the terminal equipment instantaneous required flow calculation module 6 is used for acquiring the maximum supply and return water temperature difference of safe and stable operation of each air conditioner terminal equipment 11 by the terminal equipment instantaneous required flow calculation module 6; the terminal equipment instantaneous required flow calculation module 6 is used for calculating the instantaneous required flow of each air conditioner terminal equipment according to the predicted value of each air conditioner terminal load and the maximum water supply and return temperature difference of each air conditioner terminal safe and stable operation;
the control pressure difference generator 7 is internally preset with a control pressure difference value-corresponding database of each tail end flow, can match a plurality of corresponding control pressure difference values according to the instantaneous required flow of each air conditioner tail end device, and selects the control pressure difference value with the maximum value as a control pressure difference set value for real-time control to control the water pump controller;
the water pump controller 8, the water pump controller 8 and the secondary pump P2 in the power unit of the air-conditioning water system are connected, the water pump controller is simultaneously connected with the water supply pressure sensor 9 and the water return pressure sensor 10 which are respectively arranged at the water inlet end and the water outlet end of the power unit of the air-conditioning water system and is used for obtaining the actual water supply and return pressure difference, and the water pump controller can carry out PID control on the number and the frequency of the water pumps of the secondary pump according to the actual water supply and return pressure difference acquired in real time and the deviation of a set value of the control pressure difference. Reference numeral P1 in fig. 1 denotes a primary pump in the air-conditioning water system power unit, and reference numeral 12 denotes a main unit in the air-conditioning water system power unit.
Therefore, when the system is used, the prediction of each tail end load can be realized by a tail end load prediction model according to parameters such as outdoor air temperature, outdoor air humidity, outdoor solar radiation intensity, outdoor wind speed and the like outside a room where the tail end of the air conditioner is located, which are detected in real time, and then the instantaneous required flow of each air conditioner tail end device is calculated by a tail end device instantaneous required flow calculation module according to the predicted value of each air conditioner tail end load and the maximum supply and return water temperature difference of safe and stable operation of each air conditioner tail end load; and then the control pressure difference value with the maximum value matched by the control pressure difference generator is used as a control pressure difference set value to realize real-time control. The number and frequency of secondary pumps are controlled by a water pump controller, and the actual water supply and return pressure difference is adjusted to be close to a set value of the control pressure difference, so that the variable pressure difference control of the air-conditioning water system can be realized. The device has the characteristics of simple structure, accurate control, contribution to integration and implementation and the like.
Referring to fig. 2, the terminal load prediction model adopts an artificial intelligence algorithm, and the artificial intelligence algorithm is trained by using the outdoor air temperature, the outdoor air humidity, the outdoor solar radiation intensity and the outdoor wind speed outside the room where the terminal of the air conditioner is located as input parameters and using historical data of the actual operation load of the terminal of the air conditioner corresponding to each set of input parameters as output parameters, so as to obtain the terminal load prediction model. The artificial intelligence algorithm can adopt artificial neural network, Bayes, decision tree, etc., and the specific algorithm and training process are prior art, so they are not described in detail here.
Therefore, the artificial intelligence algorithm is adopted, the prediction precision of the terminal load can be greatly improved, and the accurate prediction of the terminal load is realized.
During specific implementation, the terminal load predictor 1 is simultaneously connected with the flow sensor in the branch where each air conditioner terminal device 11 is located, the water inlet end temperature sensor and the water outlet end temperature sensor of each air conditioner terminal device, historical data of outdoor air temperature, outdoor air humidity, outdoor solar radiation intensity and outdoor wind speed in the artificial intelligence algorithm training process are acquired by the outdoor air temperature detector, the outdoor air humidity detector, the solar radiation intensity detector and the wind speed detector at time intervals in advance, and corresponding actual operation loads of each air conditioner terminal are acquired by the flow sensor in the branch where the terminal device is located and the water inlet end temperature sensor and the water outlet end temperature sensor of each air conditioner terminal device.
In this way, the accuracy of obtaining the prediction model can be better ensured.
The terminal load predictor 1 is further provided with a load day type distinguishing unit 13, and the load day type distinguishing unit 13 can distinguish date types, classify dates according to different working days and holidays and serve as one of input end parameters of an artificial intelligence algorithm of a terminal load prediction model.
In this way, the actual operating loads of the air conditioner terminals corresponding to the same outdoor environment parameters are greatly changed due to different working days and holidays, different personnel densities and different lighting and equipment utilization rates. Therefore, the load day type is introduced into the terminal load prediction model as a parameter factor for judgment so as to distinguish the influence of different working days and holidays on the terminal load. This greatly improves the accuracy of the end load prediction. In specific implementation, clustering analysis can be performed according to the historical daily load curve to obtain classification rules of different working days and holidays. And according to the relative size of the daily load of each type of load, a fixed value can be given to each type of load in the interval range of (0,1) and used as an input parameter.
In this embodiment, the terminal device instantaneous required flow calculation module 6 is connected to the water inlet end temperature sensor and the water outlet end temperature sensor of each air conditioner terminal device 11, and detects and obtains the historical maximum value of the actual supply and return water temperature difference under the safe and stable operation of each air conditioner terminal device, as the maximum supply and return water temperature difference of the safe and stable operation of each air conditioner terminal device.
This makes the calculation more accurate and reliable.
As another implementable mode, the instantaneous required flow calculation module of the end equipment obtains a supply and return water temperature difference design value according to the design parameters of each end equipment to be used as the maximum supply and return water temperature difference of the safe and stable operation of each air conditioner end equipment.
Thus, the method is simpler, more convenient and faster.
In the specific embodiment, the terminal equipment instantaneous required flow calculation module is used for calculating the instantaneous required flow of each air conditioner terminal equipment according to the predicted value of each air conditioner terminal load and the maximum supply and return water temperature difference of each air conditioner terminal safe and stable operation; specifically, the calculation is performed according to formula (5).
Li＝Qi/cρΔtmaxi (5)
In the formula, LiThe instantaneous required flow rate of the tail end i is m 3/h; qiLoad prediction value of terminal i, unit W; Δ tmaxiThe maximum temperature difference of the supply water and the return water of the safe and stable operation of the tail end i is obtained according to design data or operation conditions. i is a natural number and indicates the ith end. The remaining characters have the same meanings as in formulas 1 to 4.
In this embodiment, the database corresponding to the control pressure difference value-each terminal flow preset in the control pressure difference generator 7 is a database corresponding to the control pressure difference value-each terminal flow formed by changing the control pressure difference setting value of the control water pump and recording the chilled water flow of each terminal device under different control pressure difference setting values when all the terminal valves are fully opened. See fig. 3 for the control differential pressure generator principle.
Therefore, the obtained control pressure difference can be ensured to meet the requirements of all terminal equipment to the maximum extent, and the phenomenon of terminal underflow can not be generated. Therefore, when all the end valves are fully opened, each end flow is the minimum flow of the end valve under the control pressure difference in the fully opened state, that is, under a certain control pressure difference value, the maximum flow which can be obtained by each end device per se is certainly greater than the end flow corresponding to the control pressure difference value in the database, that is, the requirements of all the end energy utilization can be completely met, and the end underflow phenomenon cannot be generated. The principle is as follows: the tail end of the air conditioner is a parallel pipeline, and the relation between the flow and the pump lift can be expressed by a formula (6). Under a certain pressure difference set value, namely H is a fixed value, in actual operation, the opening degree of all tail end valves cannot be fully opened, so that compared with the condition that the tail end valves of a database are fully opened, the total impedance of a pipe network is increased, and the total flow L is increasedZAnd decreases. And because of the impedance S of the main pipegFor a fixed value, the maximum flow L that can be obtained at the end imaxiI.e. the flow at the end i when the valve is fully open (Si is unchanged), must be greater than the flow at the end i at this differential pressure setting in the database. Then according to the calculated flow L required by each tail endiAnd all tail end valves are controlled by pressure difference values-each tail end flow database when fully opened, and the control pressure difference value delta P for ensuring the normal operation of each tail end is obtainediChoosing the maximum Δ PiAs a control pressure difference of the variable frequency water pump (see fig. 4 in particular). Therefore, the maximum Δ P can be found by the above stepsiThe energy consumption requirements of all the tail ends can be ensured, and the tail end undercurrent phenomenon can not be generated.
Figure BDA0003209625470000101
In the formula, H is the pump head, SgIs the main pipe impedance; l iszThe total flow of the pipe network; siImpedance of a branch pipe network where the tail end i is located; l isiThe flow at the end i. The rest(s)The meaning of the characters is the same as that in formulas 1 to 5.
In this embodiment, the terminal load predictor 1, the terminal device instantaneous required flow calculation module 6, and the control pressure difference generator 7 are integrated in the same computer 14. Therefore, the required hardware equipment is simpler and is beneficial to implementation.

Claims (7)

1. An air conditioner water system control system, characterized by comprising: the terminal load predictor comprises a signal acquisition end and an outdoor data detection instrument outside a room where the tail end of each air conditioner is located, the outdoor data detection instrument comprises an outdoor air temperature detector, an outdoor air humidity detector, a solar radiation intensity detector and a wind speed detector, a terminal load prediction model is arranged in the terminal load predictor, and the terminal load prediction model can acquire the outdoor air temperature, the outdoor air humidity, the outdoor solar radiation intensity and the outdoor wind speed outside the room where the tail end of each air conditioner is located and realize prediction of each terminal load;
the system comprises a terminal equipment instantaneous required flow calculation module, a terminal equipment instantaneous required flow calculation module and a control module, wherein the terminal equipment instantaneous required flow calculation module can acquire the maximum supply and return water temperature difference of safe and stable operation of each air conditioner terminal equipment; the terminal equipment instantaneous required flow calculation module is used for calculating the instantaneous required flow of each air conditioner terminal equipment according to the predicted value of each air conditioner terminal load and the maximum water supply and return temperature difference of each air conditioner terminal safe and stable operation;
the control pressure difference generator is internally preset with a control pressure difference value-corresponding database of each tail end flow, a plurality of corresponding control pressure difference values can be matched according to the instantaneous required flow of each air conditioner tail end device, and the control pressure difference value with the maximum value is selected as a control pressure difference set value for real-time control to control the water pump controller;
the water pump controller is connected with a secondary pump in the air-conditioning water system power unit, the water pump controller is simultaneously connected with a water supply pressure sensor and a water return pressure sensor which are respectively arranged at the water inlet end and the water outlet end of the air-conditioning water system power unit and used for obtaining actual water supply and return pressure difference, and the water pump controller can carry out PID control on the number and the frequency of the water pumps of the secondary pump according to the actual water supply and return pressure difference acquired in real time and the deviation of a set value of the control pressure difference.
2. The air-conditioning water system control system as claimed in claim 1, wherein the terminal load prediction model employs an artificial intelligence algorithm, and the artificial intelligence algorithm is trained through historical data using outdoor air temperature, outdoor air humidity, outdoor solar radiation intensity and outdoor wind speed outside a room where the terminal of the air conditioner is located as input parameters, and actual operation loads of the terminals of the air conditioners corresponding to the respective sets of input parameters as output parameters, to obtain the terminal load prediction model.
3. The air-conditioning water system control system as claimed in claim 2, wherein the terminal load predictor is connected to the flow sensor in the branch in which each air-conditioning terminal device is located and the water inlet end temperature sensor and the water outlet end temperature sensor of each air-conditioning terminal device at the same time, historical data of outdoor air temperature, outdoor air humidity, outdoor solar radiation intensity and outdoor wind speed during the artificial intelligence algorithm training process are acquired by the outdoor air temperature detector, the outdoor air humidity detector, the solar radiation intensity detector and the wind speed detector at time intervals in advance, and the corresponding actual operation load of each air-conditioning terminal is calculated from data acquired by the flow sensor in the branch in which the air-conditioning terminal device is located and the water inlet end temperature sensor and the water outlet end temperature sensor of each air-conditioning terminal device.
4. The air-conditioning water system control system as claimed in claim 2, wherein the terminal load predictor is further provided with a load day type discriminating unit capable of discriminating a date type, classifying dates according to different working days and holidays, and using the classified dates as one of input parameters of the terminal load prediction model artificial intelligence algorithm.
5. The air-conditioning water system control system as claimed in claim 1, wherein the terminal equipment instantaneous required flow calculation module is connected to the water inlet end temperature sensor and the water outlet end temperature sensor of each air-conditioning terminal equipment, and detects and obtains the historical maximum value of the actual supply and return water temperature difference under the safe and stable operation of each air-conditioning terminal equipment as the maximum supply and return water temperature difference of the safe and stable operation of each air-conditioning terminal equipment.
6. The air-conditioning water system control system as claimed in claim 1, wherein the instantaneous required flow calculation module of the end equipment obtains a supply and return water temperature difference design value as a maximum supply and return water temperature difference for safe and stable operation of the end equipment of each air conditioner according to design parameters of each end equipment.
7. The air-conditioning water system control system as claimed in claim 1, wherein the control pressure difference value-each terminal flow correspondence database preset in the control pressure difference generator is formed by changing the control pressure difference set value of the control water pump with all terminal valves fully opened, recording the chilled water flow rate of each terminal equipment at different control pressure difference set values, and forming the control pressure difference value-each terminal flow correspondence database.
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