Air handling unit control method and system

Abstract

The application discloses an air handling unit control method and system, electronic equipment and a computer readable storage medium, and belongs to the technical field of air handling unit control. The method comprises the following steps: analyzing an air handling unit system, establishing an air handling unit system model; analyzing the air handling unit system model, establishing a state equation; analyzing the state equation, designing an adaptive controller through a backstepping method according to a system control target, and controlling the output of the air handling unit system through the adaptive controller. The method can completely retain the nonlinearity of the system, simultaneously consider the adjustment of the carbon dioxide concentration and the control under the condition that the temperature difference between the system inlet water and return water is unknown, and solves the problem that the existing technology linearizes the system, ignores the nonlinearity of the system, and leads to poor control effect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of air handling unit control, in particular to an air handling unit control method and system. BACKGROUND

[0002] The statements in this section merely provide background information related to the present application and do not necessarily constitute the prior art.

[0003] With the development and progress of science and technology, people's requirements for living environment are getting higher and higher today, not just meeting the traditional requirements of sheltering from the wind and rain, but also pursuing the comfort of living, and the indoor suitable environment has become a standard for measuring a good building.

[0004] The indoor environment is mainly adjusted by the air conditioning system, and the air handling unit, as the main component of the air conditioning system, can heat, cool, humidify, dehumidify and filter the air sent into the room to meet people's requirements for building environment. A good air handling unit control strategy can not only realize the adjustment of indoor environment and maintain indoor thermal comfort, but also has important significance for reducing building energy consumption and energy saving and emission reduction. However, the air handling unit is a complex nonlinear system, and the air flow, water flow, supply air temperature, supply air humidity, inlet and return water temperature and other parameters will have a certain impact on the indoor environment, making the good control of the air handling unit a great challenge.

[0005] The traditional control method such as PID is still the main control method applied to the air handling unit, but its control precision is low and energy consumption is large, which cannot meet the requirements of some places with high indoor temperature and humidity. The control strategies such as feedback linearization and sliding mode control have high requirements for the operating parameters of the air handling unit, but in actual operation, some parameters of the air handling unit cannot be accurately measured, resulting in poor control effect.

[0006] In addition, too high indoor carbon dioxide concentration will cause discomfort to indoor personnel, and when its concentration exceeds a certain limit, it will affect the health of indoor personnel. However, some current control methods only consider adjusting the indoor temperature and humidity, ignoring the influence of carbon dioxide concentration. The size of the inlet and return water temperature difference has a great influence on the control efficiency when the air handling unit is running. When the inlet and return water temperature difference is too small, the system energy consumption increases greatly, and when the inlet and return water temperature difference is too large, the flow decreases and the heat exchange efficiency decreases. However, due to the running characteristics of the air handling unit, the inlet and return water temperature difference often fluctuates and cannot be accurately measured and controlled. SUMMARY

[0007] In order to solve the problems in the prior art, the air handling unit control method, system, electronic device and computer readable storage medium are provided, so that the temperature, humidity and carbon dioxide concentration in the room can be adjusted when the temperature difference between the inlet water and return water of the air handling unit is unknown.

[0008] In a first aspect, the air handling unit control method is provided.

[0009] The air handling unit control method comprises the following steps.

[0010] The air handling unit system is analyzed to establish an air handling unit system model; the air handling unit system model is analyzed to establish a state equation.

[0011] The state equation is analyzed, an adaptive controller is designed based on the backstepping method according to the system control target, and the air handling unit system is controlled through the adaptive controller.

[0012] Further, the method further comprises the following steps.

[0013] An adaptive estimation rate of unknown coefficients is introduced, a Lyapunov function is constructed, and the adaptive controller is obtained.

[0014] Further, the air handling unit system model is represented as

[0015]

[0016] Wherein, M0 is the wet load, ρ a is the air density, V t is the indoor area, w t is the indoor humidity, w s is the indoor air supply humidity, f a is the air flow, C g is the co2 production, C s is the co2 concentration, μ is the air exchange coefficient, C pa is the air specific heat, Q0 is the load, h fg is the vaporization enthalpy, T s is the indoor air supply temperature, T t is the indoor temperature, V c is the unit volume, T0 is the ambient temperature, h w is the enthalpy of saturated water, w0 is the ambient humidity, f w is the water flow, ρ w is the water density, C pw is the water specific heat, ΔT c is the temperature difference between inlet water and return water, ρ a is the air density.

[0017] Further, the state equation is represented as

[0018]

[0019] wherein, α1, α2, α3, β1, β2, β3, β4 and β5 are non-zero constants, x1 is indoor humidity, x2 is indoor carbon dioxide concentration, x3 is indoor temperature, x4 is indoor air supply temperature, u1 is the first adaptive controller, u2 is the second adaptive controller, u3 is the third adaptive controller, w s is indoor air supply temperature, w0 is ambient temperature.

[0020] Further, the first adaptive controller is expressed as

[0021]

[0022] wherein, k1 is a normal number, α1 is a non-zero constant, β1 is a non-zero constant, z1 is a state transformation obtained quantity, w s is indoor air supply temperature, W(t) is indoor expected humidity;

[0023] The second adaptive controller is expressed as

[0024]

[0025] k2 is a normal number, α2 is a non-zero constant, β1 is a non-zero constant, z2 is a state transformation obtained

[0026] wherein,

[0027] quantity, C(t) is indoor expected carbon dioxide concentration;

[0028] The third adaptive controller is expressed as

[0029]

[0030] wherein, is an estimated value, β1 is a non-zero constant, u1 is the first adaptive controller, z3 is a state transformation obtained quantity, f1 is a self-defined parameter, k4 is a normal number, ξ is a self-defined parameter, is a virtual controller.

[0031] Further, the system control target is to make indoor temperature, indoor humidity and indoor carbon dioxide concentration track indoor expected temperature, indoor expected humidity and indoor expected carbon dioxide concentration respectively.

[0032] Further, according to the system control target, the adaptive controller is designed by backstepping method, which specifically includes:

[0033] According to the Lyapunov function, a virtual controller is introduced according to the indoor expected temperature, the indoor expected humidity and the indoor expected carbon dioxide concentration, and a first adaptive controller, a second adaptive controller and a third adaptive controller are respectively designed.

[0034] In a second aspect, the present application provides an air handling unit control system.

[0035] An air handling unit control system comprises:

[0036] A model establishment analysis module is configured to analyze the air handling unit system, establish an air handling unit system model, analyze the air handling unit system model, and establish a state equation.

[0037] An air handling unit control module is configured to design an adaptive controller based on the state equation and according to a system control target through a backstepping method, and control the output of the air handling unit system through the adaptive controller.

[0038] In a third aspect, the present application provides an electronic device.

[0039] An electronic device comprises a memory and a processor, and computer instructions stored in the memory and running on the processor, when the computer instructions are run by the processor, the steps of the air handling unit control method are completed.

[0040] In a fourth aspect, the present application provides a computer readable storage medium.

[0041] A computer readable storage medium is used to store computer instructions, when the computer instructions are executed by a processor, the steps of the air handling unit control method are completed.

[0042] Compared with the prior art, the beneficial effects of the present application are:

[0043] 1. The air handling unit is a complex multi-input multi-output nonlinear system. When the ordinary method is used for control, the system is linearized, and the nonlinearity of the system is ignored, resulting in poor control effect. The technical solution provided by the present application can completely retain the nonlinearity of the system, and consider the adjustment of the carbon dioxide concentration and the control under the condition that the water temperature difference between the inlet and outlet is unknown.

[0044] 2. The technical solution provided by the present application considers that the water temperature difference between the inlet and outlet is unknown, and can achieve good control of the indoor temperature, humidity and carbon dioxide concentration. The influence of the carbon dioxide concentration and the water temperature difference between the inlet and outlet is fully considered, the adjustment of the indoor temperature, humidity and carbon dioxide concentration can be realized, and the precise measurement control of the air handling unit can be realized. BRIEF DESCRIPTION OF DRAWINGS

[0045] The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the application, and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the application.

[0046] Figure 1 A flowchart provided for the embodiments of the present application;

[0047] Figure 2 A schematic diagram of an air handling unit provided for the embodiments of the present application. DETAILED DESCRIPTION

[0048] It should be noted that the following detailed description is merely exemplary and is intended to provide further description of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0049] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0050] The embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0051] Embodiment One

[0052] In the prior art, some parameters of the air handling unit cannot be accurately measured, resulting in poor control effect. Therefore, the present application provides an air handling unit control method. The method first analyzes the factors affecting the indoor environment and the main parameters of the air handling unit, and establishes a suitable physical model of the air handling unit according to thermodynamics, fluid mechanics and physics. The established physical model is analyzed to establish a state equation. Considering that the temperature difference between the inlet and outlet water of the air handling unit in the actual system has great uncertainty, an adaptive controller is designed for the system by combining backstepping method for unknown parameter estimation, solving the problem of unknown system parameters. Then, the stability of the designed controller is analyzed, and it is proved that the designed controller is stable in the system.

[0053] Next, combined with Figures 1-2 The air handling unit control method disclosed in the present embodiment is described in detail. The air handling unit control method disclosed in the present embodiment is described in detail.

[0054] An air handling unit control method, comprising the following steps:

[0055] S1, analyzing the air handling unit system, establishing an air handling unit system model; analyzing the air handling unit system model, establishing a simplified form of state equation.

[0056] Exemplarily, the air handling unit mainly includes a surface cooler, a mixed air chamber, a filter, a humidifier and a fan, etc. The proportion of fresh air and return air is adjusted by a control valve, and then the fresh air and return air are mixed in the mixed air chamber to adjust the indoor air quality; the surface cooler heats or cools the air, and also can dehumidify the air, so that the air sent into the room has appropriate temperature and humidity; the filter absorbs harmful substances such as dust and particles in the air, and filters the air. After layer-by-layer processing, the air sent into the room is clean and harmless, has appropriate temperature and humidity, and further maintains the comfort of the room.

[0057] The changes of indoor load, supply air temperature, fresh air ratio, air flow, supply air humidity, water flow, inlet and return water temperature, etc. will cause the change of indoor temperature and humidity, and further affect the thermal comfort of the room. Considering these influencing factors, the air handling unit is modeled according to physics and fluid mechanics, and formula (1) is obtained,

[0058]

[0059] Wherein, M0 is the wet load, ρ a is the air density, V t is the indoor area, w t is the indoor humidity, w s is the supply air humidity, f a is the air flow, C g is the co2 production, C s is the co2 concentration, μ is the air exchange coefficient, C pa is the specific heat of air, Q0 is the load, h fg is the vaporization enthalpy, T s is the supply air temperature, T t is the indoor temperature, V c is the unit volume, T0 is the environment temperature, h w is the enthalpy of saturated water, w0 is the environment humidity, f w is the water flow, ρ w is the water density, C pw is the specific heat of water, ΔT c is the inlet and return water temperature difference, ρ a is the air density.

[0060] The above differential equation represents the mathematical model of the air handling unit system. In order to facilitate analysis, we first define:

[0061]

[0062] According to the above definition, the state transformation of the air handling unit is as follows:

[0063]

[0064] wherein f1=(β3(x3-x4)-β4(x1-w s ))u1+(β3(T0-x3)+β4(x1-w0))u1u2, In reality, the above parameters represent the actual physical meaning, so α1, α2 and β i , i = 1, 2, …, 5 are non-zero constants.

[0065] In real life, both temperature and humidity are within a range and change slowly over time, so the expected indoor humidity W(t), the expected indoor temperature T(t) and the expected indoor carbon dioxide concentration C(t) are introduced, which are bounded and continuous, and continuously derivable. In the air handling unit control, the goal of designing the controller is to make the indoor temperature and humidity and the carbon dioxide concentration track the expected values, so the following transformation is introduced:

[0066]

[0067] wherein z1-z4 are the quantities obtained by state transformation;

[0068] It can be obtained that:

[0069]

[0070] S2, based on the state equation, an adaptive controller is designed by backstepping method according to the system control target, and the output of the air handling unit system is controlled by the adaptive controller.

[0071] During the operation of the air handling unit, the temperature difference between the inlet and return water is usually changing and difficult to adjust accurately, which makes the controller designed by ordinary method ineffective and unable to accurately control the indoor temperature. The temperature difference between the inlet and return water is within a range and changes stably and slowly, so designing an adaptive controller is a good solution.

[0072] Exemplarily, the specific steps include:

[0073] S201, selecting Taking the first Lyapunov function, the derivative thereof can be obtained as follows:

[0074]

[0075] The first adaptive controller u1 is designed as follows:

[0076]

[0077] Where k1 is a positive constant, substituting formula (7) into (6) yields:

[0078]

[0079] S202, Select As the second Lyapunov function, its derivative is:

[0080]

[0081] The second adaptive controller u2 is designed as follows:

[0082]

[0083] Where k2 is a positive constant, substituting formula (10) into (9) yields:

[0084]

[0085] S203, Select As the third Lyapunov function, it is differentiable:

[0086]

[0087] Introducing virtual controllers for:

[0088]

[0089] Where k3 is a positive constant.

[0090] definition We can obtain:

[0091]

[0092] S204, Select As the fourth Lyapunov function, its derivative is:

[0093]

[0094] available:

[0095]

[0096] Therefore, we can conclude that:

[0097]

[0098] Since the temperature difference between the inlet and return water is unknown, the coefficient β5 is unknown, and the controller cannot be directly designed, so the design equation is used to estimate the unknown quantity, and its estimated value and estimation error are Designing it as:

[0099]

[0100] where k4 is a positive constant, and the third adaptive controller u3 is designed as

[0101]

[0102] Then:

[0103]

[0104] Finally, define as the Lyapunov function of this step, and the derivative is:

[0105]

[0106] Substitute equation (18) into (21) to simplify:

[0107]

[0108] By designing the first, second, and third adaptive controllers, the nonlinear relationship between the input and output of the air handling unit is clarified, and the regulation considering the carbon dioxide concentration and the control of the air handling unit under the condition of unknown system inlet and return water temperature difference are realized.

[0109] S3, stability analysis of the system.

[0110] Based on the positive definite Lyapunov equation and the semi-negative derivative, the adaptive control rate is obtained and added to the adaptive controller, so that the system forms a convergent and stable controller, and the air handling unit is controlled in real time through the adaptive controller.

[0111] To ensure that the system is closed-loop stable, design the parameter k i ≥ 0, i = 1, 2, 3, 4. Since then

[0112]

[0113] Therefore, we have:

[0114]

[0115] At the same time, since From equation (23), we have:

[0116]

[0117] Using the boundedness of the closed-loop system states and equation (5), by the barbalat lemma, we have: And we have Then the system is stable.

[0118] Embodiment Two

[0119] The embodiment discloses an air handling unit control system, comprising:

[0120] The model establishment analysis module is configured to analyze the air handling unit system, establish an air handling unit system model, analyze the air handling unit system model, and establish a state equation.

[0121] The air handling unit control module is configured to analyze the state equation, design an adaptive controller through a backstepping method according to a system control target, and control the output of the air handling unit system through the adaptive controller.

[0122] It should be noted that the above model establishment analysis module and air handling unit control module correspond to the steps in embodiment one, and the above modules and the corresponding steps have the same examples and application scenarios, but are not limited to the above embodiment one. It should be noted that the above modules as part of the system can be executed in a computer system such as a set of computer executable instructions.

[0123] Embodiment Three

[0124] The embodiment three of the present application provides an electronic device, comprising a memory and a processor, and computer instructions stored in the memory and running on the processor, when the computer instructions are executed by the processor, the steps of the above air handling unit control method are completed.

[0125] Embodiment Four

[0126] The embodiment four of the present application provides a computer readable storage medium for storing computer instructions, when the computer instructions are executed by the processor, the steps of the above air handling unit control method are completed.

[0127] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 one or more flow or blocks Figure 1 means for functionally implementing the steps in one or more flow or blocks

[0128] These computer program instructions can also be stored in a computer readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer readable memory produce an article of manufacture including instructions which implement the function specified in the flowchart block or blocks. Figure 1 one or more flow or blocks Figure 1 means for functionally implementing the steps in one or more flow or blocks

[0129] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 one or more flow or blocks Figure 1 means for functionally implementing the steps in one or more flow or blocks

[0130] The above description of the various embodiments can have emphasized certain aspects of the various embodiments, which description is not to be taken to mean that other aspects of the embodiments are not equally valid and important. Those skilled in the art will readily observe that numerous modifications and alterations of the device and method can be made without departing from the scope of the application.

[0131] The specific embodiments described herein are illustrative and not restrictive in nature. Many variations and modifications will become apparent to those skilled in the art upon consideration of the specification and the drawings. Accordingly, the particular embodiments as described herein are not intended to be key to the scope of the present application but are merely constructive aids in providing a broader appreciation of the principles and concepts underlying the present application. Therefore, it will be understood that changes and modifications can be made by those skilled in the art, which fall within the scope of the various embodiments. Those skilled in the art will readily appreciate that other applications can be implemented using two or more of the embodiments.

Claims

1. An air handling unit control method, characterized by, Comprising: analyzing the air handling unit system, establishing an air handling unit system model; analyzing the air handling unit system model, establishing a state equation; the air handling unit system model is expressed as: wherein, is the wet load, is the air density, is the indoor area, is the indoor humidity, is the indoor supply air humidity, is the air flow rate, is the generation amount, is the concentration, is the air exchange coefficient, is the air specific heat, is the load, is the vaporization enthalpy, is the indoor supply air temperature, is the indoor temperature, is the unit volume, is the ambient temperature, is the enthalpy of saturated water, is the ambient humidity, is the water flow rate, is the water density, is the water specific heat, is the inlet and return water temperature difference, is the air density; The state equation is expressed as: wherein, , , , , , , , , , x 1 is the indoor humidity, x 2 is the indoor carbon dioxide concentration, x 3 is the indoor temperature, x 4 is the indoor supply air temperature, u 1 is the first adaptive controller, u 2 is the second adaptive controller, u 3 is the third adaptive controller, w s is the indoor supply air humidity, w 0 is the ambient humidity; The following transformation is introduced: ， Wherein, z1-z4 is the quantity obtained by state transformation; Analyzing the state equation, designing an adaptive controller based on backstepping method according to the system control target, and controlling the air handling unit system through the adaptive controller; An adaptive estimation rate of unknown coefficients is introduced, a Lyapunov function is constructed, and an adaptive controller is obtained; The first adaptive controller is expressed as: wherein, is a normal number, is a non-zero constant, is a non-zero constant, z1 is a quantity resulting from a state transformation, w s is the indoor supply air humidity, is the desired indoor humidity; The second adaptive controller is expressed as: where k2 is a non-zero constant, is a non-zero constant, is a non-zero constant, and z2 is a quantity resulting from a state transformation, is the desired indoor carbon dioxide concentration; Let , be an unknown nonzero constant, and let , , be its estimate and the estimate error, respectively. Design The third adaptive controller is then represented as: ， wherein, is an estimated value, is a non-zero constant, ui is a first adaptive controller, z3 is a quantity resulting from a state transformation, is a normal number, is a self-defined parameter, is a virtual controller, ， wherein is a normal number; The system control target is to make the indoor temperature, indoor humidity and indoor carbon dioxide concentration respectively track the indoor expected temperature, indoor expected humidity and indoor expected carbon dioxide concentration.

2. An air handling unit control system employing the air handling unit control method as claimed in claim 1, characterized by, Comprising: The model establishment analysis module is configured to analyze the air handling unit system, establish an air handling unit system model; analyzing the air handling unit system model, establishing a state equation; The air handling unit system model is expressed as: wherein, is the wet load, is the air density, is the indoor area, is the indoor humidity, is the indoor supply air humidity, is the air flow rate, is the generation amount, is the concentration, is the air exchange coefficient, is the air specific heat, is the load, is the vaporization enthalpy, is the indoor supply air temperature, is the indoor temperature, is the unit volume, is the ambient temperature, is the enthalpy of saturated water, is the ambient humidity, is the water flow rate, is the water density, is the water specific heat, is the water inlet and return temperature difference, is the air density; The air handling unit control module is configured to analyze the state equation, design an adaptive controller through backstepping method according to the system control target, and control the output of the air handling unit system through the adaptive controller.

3. An electronic device, comprising: Comprising a memory and a processor, and computer instructions stored on the memory and running on the processor, when the computer instructions are run by the processor, the steps of the control method of claim 1 are completed.

4. A computer-readable storage medium, characterized in that, For storing computer instructions, when the computer instructions are executed by the processor, the steps of the control method of claim 1 are completed.

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