CN113803855A - Three-point clamping position self-adaptive AHU control method and system - Google Patents
Three-point clamping position self-adaptive AHU control method and system Download PDFInfo
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- CN113803855A CN113803855A CN202010546784.3A CN202010546784A CN113803855A CN 113803855 A CN113803855 A CN 113803855A CN 202010546784 A CN202010546784 A CN 202010546784A CN 113803855 A CN113803855 A CN 113803855A
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F11/00—Control or safety arrangements
- F24F11/62—Control or safety arrangements characterised by the type of control or by internal processing, e.g. using fuzzy logic, adaptive control or estimation of values
- F24F11/63—Electronic processing
- F24F11/64—Electronic processing using pre-stored data
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F11/00—Control or safety arrangements
- F24F11/70—Control systems characterised by their outputs; Constructional details thereof
- F24F11/80—Control systems characterised by their outputs; Constructional details thereof for controlling the temperature of the supplied air
- F24F11/83—Control systems characterised by their outputs; Constructional details thereof for controlling the temperature of the supplied air by controlling the supply of heat-exchange fluids to heat-exchangers
- F24F11/84—Control systems characterised by their outputs; Constructional details thereof for controlling the temperature of the supplied air by controlling the supply of heat-exchange fluids to heat-exchangers using valves
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F11/00—Control or safety arrangements
- F24F11/89—Arrangement or mounting of control or safety devices
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- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B30/00—Energy efficient heating, ventilation or air conditioning [HVAC]
- Y02B30/70—Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating
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Abstract
The invention relates to a three-point clamping position self-adaptive AHU control method and a system. The control method comprises the following steps: acquiring the terminal water inlet temperature, the terminal water outlet temperature and the machine room water outlet temperature; determining a first temperature difference according to the tail end water outlet temperature and the tail end water inlet temperature; comparing the first temperature difference with a preset temperature difference value to obtain a first comparison result; regulating the opening degree of the proportional valve until the first comparison result is 0, and correspondingly outputting a first opening degree value; updating according to the first opening value to obtain a first opening updating range; determining a second temperature difference according to the water outlet temperature of the machine room and the water inlet temperature at the tail end; comparing the second temperature difference with a preset temperature difference value to obtain a second comparison result; regulating the opening degree of the proportional valve until the second comparison result is 0, and correspondingly outputting a second opening degree value; updating the first opening degree updating range to obtain a second opening degree updating range; and regulating and controlling the proportional valve according to the second opening updating range, and continuously repeating the steps to dynamically complete AHU control, so that the AHV is accurately controlled while hydraulic balance is considered.
Description
Technical Field
The invention relates to the field of air conditioner control, in particular to a three-point clamping position self-adaptive AHU control method and system.
Background
In the heating ventilation air conditioning engineering of buildings, the adjustment of hydraulic balance is an important link. The hydraulic balance adjustment is an important index for determining the operation energy consumption and stability of the whole air conditioning system. In order to well regulate and control water conservancy balance, a large number of balance valves are used in actual engineering, but because the pipelines of the air conditioner tail end system are very complicated, a large number of professionals are needed when the balance valves of all pipelines are debugged, the debugging mode not only consumes time and labor, but also has poor debugging result.
Further, the conventional control method can adjust the temperature of the room, but cannot adjust the hydraulic balance at the same time. When the system is debugged, an expensive balance valve is firstly needed to enable each tail end to be statically and hydraulically balanced so as to meet the characteristics of the tail end valve (such as the kv value of the valve parameter and the like) and a control curve corresponding to the characteristics (namely the PID parameter of the DDC). The above situations not only require professional technical field adjustment, but also require a lot of labor, time and effort.
In the actual operation condition after the debugging is finished, the phenomenon of small temperature difference and large flow is serious, so that the water inlet temperature of the unit is low (during refrigeration), and the efficiency of the unit is reduced.
The following describes a specific control procedure by taking the conventional control for the end as an example. The control process of other components in the heating, ventilating and air conditioning engineering is similar to the tail end control process.
When the return air temperature (equal to the environmental temperature or the target temperature) is higher than or lower than the set temperature, the PLC calculates and outputs a valve opening signal, and water flows through the tail end to perform refrigeration or heating. It mainly has the following control situations:
case 1: the flow at the end is equal to the design flow
Since the indoor temperature is 32 degrees (set value) and the load is large when the air conditioner is started, the temperature Δ T is greater than 5 degrees as can be seen from a formula Q ═ M × C × Δ T (note: the standard design temperature difference of the air conditioner is 5 degrees). Wherein, the delta T is the temperature difference of water inlet and outlet at the tail end; when in refrigeration, delta T is equal to water outlet T6-water inlet T3, and the calculation process is just opposite when in heating.
After a period of operation, the temperature gradually decreases, and when the room temperature (return air temperature T4) reaches 27 degrees, Δ T is 5 degrees (the water flow rate is the same as the flow rate of the standard equipment).
The running temperature is continued to drop, and the temperature reaches 24 degrees and approaches the target temperature, and the temperature is less than 5 degrees according to the formula Q.
Wherein, under low load (flow), the water flow is increased by 1 percent, and the heat dissipation capacity is increased by 3 percent; at high load (flow), the water flow increases by 1% and the heat dissipation increases by 0.18%.
Due to the hydraulic balance design of the air conditioning system and the production of products, the air conditioning system is designed, manufactured and debugged according to the theory that the delta T is 5 degrees. At <5 degrees when the target temperature is approached, i.e., the water flow is greater than the design parameter. Several problems arise here: 1. the return water temperature is lower than the designed 5 ℃, so that the water inlet temperature of the unit is low, and the efficiency is reduced; 2. large water flow, resulting in possible "starvation" of water at other extremities of the system; 3. the 80% operation time load rate of the air conditioning system is 30-50%, and the hydraulic imbalance of the whole system is caused and deviates from the design value.
Case 2: because the terminal water resistance has larger difference, the flow with small water resistance is large under the same water inlet and outlet pressure difference, and the temperature difference is lower than 5 degrees and deviates from the design value according to the explanation.
Case 3: because the central air-conditioning water pipe is complicated, the pressure difference of the tail end close to the machine room is large, the pressure difference of the tail end far away from the machine room is small, the tail end water flow far away from the machine room is insufficient, and the effect is poor.
In engineering, 2 methods are commonly adopted for solving the problems, and 1, hydraulic balance adjustment is carried out, but the method has the defects of time and labor waste, high professional requirements and the like; 2. the power of a water pump in a machine room is increased to make up for the pressure difference requirement of the worst tail end, but the method has the problems of energy consumption, deviation of small temperature difference of a system from a design value, poor efficiency and the like.
Therefore, it is an urgent technical problem to be solved in the art to provide a control method capable of controlling both the target temperature and the hydraulic balance.
Disclosure of Invention
In order to solve the above problems in the prior art, the present invention provides a three-point clamp adaptive AHU control method and system.
In order to achieve the purpose, the invention provides the following scheme:
a three-point clamp position self-adaptive AHU control method comprises the following steps:
acquiring a terminal water inlet temperature, a terminal water outlet temperature and a temperature difference preset value;
acquiring the opening range of the proportional valve; the opening range is 0-100%;
determining a first temperature difference according to the tail end water outlet temperature and the tail end water inlet temperature;
comparing the first temperature difference with the preset temperature difference value to obtain a first comparison result;
regulating the opening degree of the proportional valve until the first comparison result is 0, and correspondingly outputting the opening degree value of the proportional valve at the moment, and recording the opening degree value as a first opening degree value;
acquiring a preset minimum opening value, and updating the opening range of the proportional valve according to the first opening value; recording the updated opening degree range as a first opening degree updating range; the first opening degree update range is as follows: presetting a minimum opening value to a first opening value;
acquiring the water outlet temperature of a machine room;
determining a second temperature difference according to the outlet water temperature of the machine room and the inlet water temperature at the tail end;
comparing the second temperature difference with the preset temperature difference value to obtain a second comparison result;
regulating the opening degree of the proportional valve until the second comparison result is 0, and correspondingly outputting the opening degree value of the proportional valve at the moment, and recording the opening degree value as a second opening degree value;
updating the first opening degree updating range according to the second opening degree value to obtain a second opening degree updating range; the second opening degree update range is as follows: second to first opening values;
and regulating and controlling the proportional valve according to the second opening updating range, and returning to the preset values of the terminal water inlet temperature, the terminal water outlet temperature and the temperature difference so as to dynamically complete AHU control.
Preferably, the obtaining the opening range of the proportional valve further comprises:
determining a third temperature difference according to the total outlet water temperature of the machine room and the terminal inlet water temperature;
comparing the third temperature difference with the preset temperature difference value to obtain a third comparison result;
when the third comparison result shows that the first temperature difference is smaller than or equal to the preset temperature difference value, outputting the minimum value of the opening range;
when the third comparison result shows that the third temperature difference is larger than the preset temperature difference value, outputting the maximum value of the opening range;
and determining the opening range of the proportional valve according to the minimum value and the maximum value.
Preferably, the first opening value is smaller than the maximum value of the opening range;
the second opening value is less than or equal to the first opening value.
Preferably, the preset temperature difference value is 5 ℃.
Preferably, the preset minimum opening value is 30%.
A three-point clamp adaptive AHU control system comprising:
the first acquisition module is used for acquiring the tail end water inlet temperature, the tail end water outlet temperature and the preset temperature difference value;
the second acquisition module is used for acquiring the opening range of the proportional valve; the opening range is 0-100%;
the first temperature difference determining module is used for determining a first temperature difference according to the tail end water outlet temperature and the tail end water inlet temperature;
the first comparison module is used for comparing the first temperature difference with the preset temperature difference value to obtain a first comparison result;
the first opening value output module is used for regulating and controlling the opening of the proportional valve until the first comparison result is 0, and correspondingly outputting the opening value of the proportional valve at the moment and recording the opening value as a first opening value;
the first opening range updating module is used for acquiring a preset minimum opening value and updating the opening range of the proportional valve according to the first opening value; recording the updated opening degree range as a first opening degree updating range; the first opening degree update range is as follows: presetting a minimum opening value to a first opening value;
the third acquisition module is used for acquiring the temperature of the water outlet of the machine room;
the second temperature difference determining module is used for determining a second temperature difference according to the outlet water temperature of the machine room and the inlet water temperature at the tail end;
the second comparison module is used for comparing the second temperature difference with the preset temperature difference value to obtain a second comparison result;
the second opening value output module is used for regulating and controlling the opening of the proportional valve until the second comparison result is 0, and correspondingly outputting the opening value of the proportional valve at the moment and recording the opening value as a second opening value;
the second opening degree range updating module is used for updating the first opening degree updating range according to the second opening degree value to obtain a second opening degree updating range; the second opening degree update range is as follows: second to first opening values;
and the regulating module is used for regulating and controlling the proportional valve according to the second opening updating range and returning to the preset values of the acquired terminal water inlet temperature, the terminal water outlet temperature and the temperature difference so as to dynamically complete AHU control.
Preferably, the system further comprises:
the third temperature difference determining module is used for determining a third temperature difference according to the total outlet water temperature of the machine room and the terminal inlet water temperature;
the third comparison module is used for comparing the third temperature difference with the preset temperature difference value to obtain a third comparison result;
the minimum value output module is used for outputting the minimum value of the opening range when the third comparison result shows that the first temperature difference is smaller than or equal to the preset temperature difference value;
the maximum value output module is used for outputting the maximum value of the opening range when the third comparison result shows that the third temperature difference is larger than the preset temperature difference value;
and the opening range determining module is used for determining the opening range of the proportional valve according to the minimum value and the maximum value.
A three-point clamp adaptive AHU control system comprising: the system comprises a three-level PID controller, a proportional valve and a plurality of temperature sensors;
the temperature sensors are used for acquiring the water inlet temperature at the tail end, the water outlet temperature at the tail end and the water outlet temperature of the machine room;
the three-stage PID controller is respectively connected with the proportional valve and the temperature sensor and is used for determining the opening range of the proportional valve according to the terminal water inlet temperature, the terminal water outlet temperature and the machine room water outlet temperature by adopting the control method;
the proportional valve is arranged on the water return pipeline.
Preferably, the plurality of temperature sensors includes: a total water supply temperature sensor, an inlet water temperature sensor and an outlet water temperature sensor;
the total water supply temperature sensor is arranged on a connecting pipeline between the machine room and the tail end; the water inlet temperature sensor is arranged at a water inlet at the tail end; the water outlet temperature sensor is arranged at a water outlet at the tail end.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
according to the three-point clamp position self-adaptive AHU control method and the system, the opening range of the row valve can be continuously updated according to the acquired tail end water inlet temperature, the tail end water outlet temperature and the machine room water outlet temperature, so that the AHV (Air handling Unit) in the Air conditioning system can be accurately controlled.
And all the tail ends adopt the same control logic, and after the air conditioning system is stable, all the tail ends can realize self-adaptive adjustment, so that the target temperature can be controlled, and hydraulic balance can be considered.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.
FIG. 1 is a flow chart of a three-point clamp adaptive AHU control method provided by the present invention;
FIG. 2 is a schematic structural diagram of a first three-point clamp adaptive AHU control system provided by the present invention;
FIG. 3 is a schematic structural diagram of a second three-point clamp adaptive AHU control system provided by the present invention;
FIG. 4 is a diagram illustrating the results of three levels of PID output ranges in an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention aims to provide a three-point clamping self-adaptive AHU control method and a three-point clamping self-adaptive AHU control system which can control target temperature and balance hydraulic power, so as to solve the problems of time and labor consumption and low control precision of a control process in the prior art.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
Fig. 1 is a flowchart of a three-point clamp adaptive AHU control method provided in the present invention, and as shown in fig. 1, a three-point clamp adaptive AHU control method includes:
step 100: and acquiring preset values of the tail end water inlet temperature, the tail end water outlet temperature and the temperature difference. The preset temperature difference value is preferably 5 degrees centigrade, but is not limited thereto, and can be adjusted correspondingly according to the actual requirements of the user.
Step 101: and acquiring the opening range of the proportional valve. The opening range is 0-100%.
Step 102: a first temperature difference is determined from the terminal outlet water temperature and the terminal inlet water temperature.
Step 103: and comparing the first temperature difference with a preset temperature difference value to obtain a first comparison result.
Step 104: and regulating the opening degree of the proportional valve until the first comparison result is 0, and correspondingly outputting the opening degree value of the proportional valve at the moment and recording as the first opening degree value.
Step 105: and acquiring a preset minimum opening value, and updating the opening range of the proportional valve according to the first opening value. The updated opening degree range is referred to as a first opening degree update range. The first opening degree update range is: the minimum opening value is preset to the first opening value. The preset minimum opening value is preferably 30%, but is not limited thereto, and may be set according to an actual operation degree of the air conditioning system.
Step 106: and acquiring the water outlet temperature of the machine room.
Step 107: and determining a second temperature difference according to the outlet water temperature of the machine room and the inlet water temperature of the tail end.
Step 108: and comparing the second temperature difference with a preset temperature difference value to obtain a second comparison result.
Step 109: and regulating the opening degree of the proportional valve until the second comparison result is 0, and correspondingly outputting the opening degree value of the proportional valve at the moment and recording as a second opening degree value.
Step 110: and updating the first opening degree updating range according to the second opening degree value to obtain a second opening degree updating range. The second opening degree update range is: second to first opening values.
Step 111: and updating the range regulation and control proportional valve according to the second opening, and returning to the preset values of the terminal inlet water temperature, the terminal outlet water temperature and the temperature difference so as to dynamically complete the AHU control.
Wherein the first opening value is smaller than the maximum value of the opening range. The second opening value is less than or equal to the first opening value.
As a preferred implementation manner of this embodiment, before obtaining the opening range of the proportional valve, the method may further include:
and determining a third temperature difference according to the total outlet water temperature and the terminal inlet water temperature of the machine room.
And comparing the third temperature difference with a preset temperature difference value to obtain a third comparison result.
And outputting the minimum value of the opening range when the third comparison result shows that the first temperature difference is smaller than or equal to the preset temperature difference value.
And when the third comparison result shows that the third temperature difference is larger than the preset temperature difference value, outputting the maximum value of the opening range.
And determining the opening range of the proportional valve according to the minimum value and the maximum value.
Aiming at the three-point clamp self-adaptive AHU control method, the invention also correspondingly provides two three-point clamp self-adaptive AHU control systems.
As shown in fig. 2, a first three-point clamp adaptive AHU control system includes: the temperature difference measurement device comprises a first obtaining module 200, a second obtaining module 201, a first temperature difference determining module 202, a first comparing module 203, a first opening value output module 204, a first opening range updating module 205, a third obtaining module 206, a second temperature difference determining module 207, a second comparing module 208, a second opening value output module 209, a second opening range updating module 210 and a regulating module 211.
The first obtaining module 200 is configured to obtain a terminal water inlet temperature, a terminal water outlet temperature, and a temperature difference preset value.
The second obtaining module 201 is used for obtaining the opening range of the proportional valve. The opening range is 0-100%.
The first temperature difference determination module 202 is configured to determine a first temperature difference according to the terminal outlet water temperature and the terminal inlet water temperature.
The first comparing module 203 is configured to compare the first temperature difference with a preset temperature difference value to obtain a first comparison result.
The first opening value output module 204 is configured to regulate and control the opening of the proportional valve until the first comparison result is 0, and output the opening value of the proportional valve at this time correspondingly, which is recorded as the first opening value.
The first opening range updating module 205 is configured to obtain a preset minimum opening value, and update the opening range of the proportional valve according to the first opening value. The updated opening degree range is referred to as a first opening degree update range. The first opening degree update range is: the minimum opening value is preset to the first opening value.
The third obtaining module 206 is configured to obtain the temperature of the machine room outlet water.
The second temperature difference determining module 207 is configured to determine a second temperature difference according to the machine room outlet water temperature and the terminal inlet water temperature.
The second comparing module 208 is configured to compare the second temperature difference with a preset temperature difference value to obtain a second comparison result.
The second opening value output module 209 is configured to regulate the opening of the proportional valve until the second comparison result is 0, and output the opening value of the proportional valve at this time correspondingly, which is recorded as the second opening value.
The second opening degree range updating module 210 is configured to update the first opening degree updating range according to the second opening degree value, so as to obtain a second opening degree updating range. The second opening degree update range is: second to first opening values.
The regulating module 211 is configured to regulate the proportional valve according to the second opening update range, and return to "acquiring the terminal water inlet temperature, the terminal water outlet temperature, and the preset temperature difference value" to dynamically complete AHU control.
As another preferred embodiment of the present invention, the system further includes: the device comprises a third temperature difference determining module, a third comparing module, a minimum value output module, a maximum value output module and an opening range determining module.
The third temperature difference determining module is used for determining a third temperature difference according to the total water outlet temperature and the tail end water inlet temperature of the machine room.
And the third comparison module is used for comparing the third temperature difference with the preset temperature difference value to obtain a third comparison result.
And the minimum value output module is used for outputting the minimum value of the opening range when the third comparison result shows that the first temperature difference is smaller than or equal to the preset temperature difference value.
And the maximum value output module is used for outputting the maximum value of the opening range when the third comparison result shows that the third temperature difference is larger than the preset temperature difference value.
The opening range determining module is used for determining the opening range of the proportional valve according to the minimum value and the maximum value.
As shown in fig. 3, a second three-point clamp adaptive AHU control system eliminates the constant flow valve in the conventional design.
The specific three-point clamping position self-adaptive AHU control system comprises: a three-stage PID controller 8, a proportional valve 7 and a plurality of temperature sensors. Wherein, the Chinese name of PID is proportional-integral-differential, English is all called: presentation-integral-derivative.
The temperature sensors are used for acquiring the tail end water inlet temperature, the tail end water outlet temperature and the machine room water outlet temperature.
The three-level PID controller 8 is respectively connected with the proportional valve 7 and the temperature sensor and is used for determining the opening range of the proportional valve 7 according to the terminal water inlet temperature, the terminal water outlet temperature and the machine room water outlet temperature by adopting the control method provided by the invention.
The proportional valve 7 is provided on the return line.
Wherein the plurality of temperature sensors include: a total water supply temperature sensor 2, an inlet water temperature sensor 3 and an outlet water temperature sensor 6.
The total water supply temperature sensor 2 is arranged on a connecting pipeline between the machine room and the tail end. The inlet water temperature sensor 3 is installed at the inlet of the tail end. The water outlet temperature sensor 6 is arranged at the water outlet at the tail end.
In FIG. 3, terminal 1 is the first terminal, terminal 2 is the second terminal, and so on, and terminal N is the Nth terminal.
In order to further reduce the influence caused by loss, the second three-point clamp adaptive AHU control system provided by the present invention may further include an outlet air temperature sensor 4 and a return air temperature sensor 5.
Wherein return air temperature sensor 5 is used for detecting indoor temperature, and air-out temperature sensor 4 is used for detecting the terminal loss temperature that leads to because of the circulation of air.
The following provides a specific embodiment to further illustrate the scheme of the present invention, and the embodiment of the present invention is described by taking the second three-point clamp adaptive AHU control system as an example to implement the above-mentioned control method.
Firstly, based on the actual control condition of the air conditioning engineering, the temperature difference between the water outlet of the machine room 1 and the water inlet at the tail end is divided into two conditions:
during refrigeration, the temperature difference between the water outlet of the machine room 1 and the water inlet at the tail end is equal to the water inlet temperature at the tail end T1-the water outlet of the machine room 1T 0.
During heating, the temperature difference between the water outlet of the machine room 1 and the water inlet at the tail end is equal to the water outlet temperature T0 of the machine room 1 and the water inlet temperature T1 at the tail end.
The water temperature difference between the inlet and the outlet of the tail end is as follows:
the refrigeration temperature difference is the terminal water outlet temperature T2-the terminal water inlet temperature T1.
The heating temperature difference is equal to the terminal water inlet temperature T1-the terminal water outlet temperature T2.
The temperature difference between the total water supply and the equipment water inlet is also divided into two conditions:
during refrigeration, the temperature difference between the total water supply and the equipment water inlet is equal to the equipment water supply temperature-the total water supply temperature.
During heating: the temperature difference between the total water supply and the equipment water inlet is the total water supply temperature-the equipment water supply temperature
The larger the temperature difference is, the larger the output is, the smaller the temperature difference is, the smaller the output is but not less than the minimum a value, namely, the output range is a-100%.
The invention adopts a control system to adjust the hydraulic balance based on a clamping output method, and the specific control process is as follows:
step 1, adopting primary PID control to the main machine room 1
The purpose of adopting one-level PID control is to compare the total water outlet temperature and the terminal water inlet temperature of the machine room 1, and specifically comprises the following steps:
if the temperature difference is within the set value, outputting the minimum value of the valve opening.
Assuming that the temperature difference is larger than the set value, the opening value of the valve is output, and the magnitude of the output value and the magnitude of the temperature difference are positive logicals, and the maximum value is 100%.
Step 2: using two-stage PID control for the tail end
In order to prevent the large flow and small temperature difference at the tail end and cause insufficient water flow for other tail ends, two-stage PID calculation is set.
The operation principle of the second-level PID is as follows: and (4) comparing the temperature with a set temperature difference (5 ℃ in the heating and ventilation standard) after detecting the temperature difference of the tail end inlet and outlet water.
The PID calculation logic is positive logic, namely the temperature difference is larger than the set value and is output more, the temperature difference is smaller than the set value and is output less, and the maximum value of the secondary control is smaller than the maximum value of the primary control.
Assuming that the output parameter B of the secondary PID is 70%, the output range B of the secondary PID is: a is more than or equal to b is less than or equal to 100 percent.
For example, the maximum value of the opening of the proportional valve 7 calculated by the PID control is 60%, and the value calculated after the comparison between the water outlet temperature and the tail end temperature of the machine room 1 is 95% (two-stage PID control), then 95% is selected to be sent to the PID controller 8, and the opening range of the proportional valve 7 is controlled to be 0-95%.
The above description solves the problem that under different working conditions, the tail water flow can be automatically adjusted according to the change of the working conditions, so that the water flow always ensures a set value. However, the temperature difference limits the maximum opening value of the proportional valve 7, which brings a new problem, when the unit is just started, the temperature of the inlet and outlet water at the tail end is basically consistent, that is, the temperature Δ T is close to 0 degree, when the unit is just started by adopting the method described above, the opening degree of the proportional valve 7 is limited, the water delivery speed of the machine room 1 is too slow (the resistance is large, the flow rate is small), the cooling and heating speed is slow, and in severe cases, the standard water flow may not be obtained at the far end "forever", and the cooling and heating effects are poor.
And step 3: in order to solve the above mentioned disadvantages of the "two-stage PID" approach, the control must take into account the difference between the machine room 1 outlet water temperature T0 and the itself T1 inlet water temperature. Under the condition of not considering pipeline loss, the temperature difference between the water outlet of the machine room 1 and the water inlet of the equipment after water flow balance is 0 ℃. If the difference between the outlet water temperature of the machine room 1 and the inlet water temperature of the equipment is large, the PID controller 8 calculates the difference so as to output a maximum value (for example, the opening degree is 100% or 80%) of the opening degree of the proportional valve 7 to forcibly interfere with the minimum value of the secondary PID when the difference is too large. That is, the maximum value is set as the minimum value of the opening degree of the two-stage PID control proportional valve 7.
The output range of the three-level PID is shown in fig. 4, and in fig. 4, the opening range of the one-level PID control is: the interval of 0-100% is as follows: the minimum register is a and the maximum register is x.
The opening range of the second-level PID control is as follows: in the interval of 0-100%, the minimum register is b, and the maximum register is Y.
The opening range of the three-level PID control is as follows: the value a is within the interval of 100 percent, the minimum value is a constant a, and the maximum register is Z.
Remarking: x < ═ 100%, Y < ═ 100%, Z < ═ 100% (a is a setting constant > 0).
All the tail ends in the system adopt the same control logic, and after the system is stabilized, all the tail ends can be adjusted in a self-adaptive mode, so that a 'fool' installation method is achieved, the target temperature can be controlled, hydraulic balance can be considered, the control method solves the problem, good verification is achieved in actual use, a balance valve and static hydraulic balance adjustment are cancelled, and the effect of self-adaptive hydraulic balance is achieved.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. For the system disclosed by the embodiment, the description is relatively simple because the system corresponds to the method disclosed by the embodiment, and the relevant points can be referred to the method part for description.
The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.
Claims (9)
1. A three-point clamp position self-adaptive AHU control method is characterized by comprising the following steps:
acquiring a terminal water inlet temperature, a terminal water outlet temperature and a temperature difference preset value;
acquiring the opening range of the proportional valve; the opening range is 0-100%;
determining a first temperature difference according to the tail end water outlet temperature and the tail end water inlet temperature;
comparing the first temperature difference with the preset temperature difference value to obtain a first comparison result;
regulating the opening degree of the proportional valve until the first comparison result is 0, and correspondingly outputting the opening degree value of the proportional valve at the moment, and recording the opening degree value as a first opening degree value;
acquiring a preset minimum opening value, and updating the opening range of the proportional valve according to the first opening value; recording the updated opening degree range as a first opening degree updating range; the first opening degree update range is as follows: presetting a minimum opening value to a first opening value;
acquiring the water outlet temperature of a machine room;
determining a second temperature difference according to the outlet water temperature of the machine room and the inlet water temperature at the tail end;
comparing the second temperature difference with the preset temperature difference value to obtain a second comparison result;
regulating the opening degree of the proportional valve until the second comparison result is 0, and correspondingly outputting the opening degree value of the proportional valve at the moment, and recording the opening degree value as a second opening degree value;
updating the first opening degree updating range according to the second opening degree value to obtain a second opening degree updating range; the second opening degree update range is as follows: second to first opening values;
and regulating and controlling the proportional valve according to the second opening updating range, and returning to the preset values of the terminal water inlet temperature, the terminal water outlet temperature and the temperature difference so as to dynamically complete AHU control.
2. The three-point clamp adaptive AHU control method of claim 1 wherein obtaining the range of opening of the proportional valve further comprises:
determining a third temperature difference according to the total outlet water temperature of the machine room and the terminal inlet water temperature;
comparing the third temperature difference with the preset temperature difference value to obtain a third comparison result;
when the third comparison result shows that the first temperature difference is smaller than or equal to the preset temperature difference value, outputting the minimum value of the opening range;
when the third comparison result shows that the third temperature difference is larger than the preset temperature difference value, outputting the maximum value of the opening range;
and determining the opening range of the proportional valve according to the minimum value and the maximum value.
3. The three-point clamp adaptive AHU control method of claim 2, wherein the first opening value is less than a maximum value of the opening range;
the second opening value is less than or equal to the first opening value.
4. The three-point clamp adaptive AHU control method of claim 1, wherein the preset temperature difference value is 5 degrees Celsius.
5. The three-point clamp adaptive AHU control method of claim 1 wherein the preset minimum opening value is 30%.
6. A three-point clamp adaptive AHU control system, comprising:
the first acquisition module is used for acquiring the tail end water inlet temperature, the tail end water outlet temperature and the preset temperature difference value;
the second acquisition module is used for acquiring the opening range of the proportional valve; the opening range is 0-100%;
the first temperature difference determining module is used for determining a first temperature difference according to the tail end water outlet temperature and the tail end water inlet temperature;
the first comparison module is used for comparing the first temperature difference with the preset temperature difference value to obtain a first comparison result;
the first opening value output module is used for regulating and controlling the opening of the proportional valve until the first comparison result is 0, and correspondingly outputting the opening value of the proportional valve at the moment and recording the opening value as a first opening value;
the first opening range updating module is used for acquiring a preset minimum opening value and updating the opening range of the proportional valve according to the first opening value; recording the updated opening degree range as a first opening degree updating range; the first opening degree update range is as follows: presetting a minimum opening value to a first opening value;
the third acquisition module is used for acquiring the temperature of the water outlet of the machine room;
the second temperature difference determining module is used for determining a second temperature difference according to the outlet water temperature of the machine room and the inlet water temperature at the tail end;
the second comparison module is used for comparing the second temperature difference with the preset temperature difference value to obtain a second comparison result;
the second opening value output module is used for regulating and controlling the opening of the proportional valve until the second comparison result is 0, and correspondingly outputting the opening value of the proportional valve at the moment and recording the opening value as a second opening value;
the second opening degree range updating module is used for updating the first opening degree updating range according to the second opening degree value to obtain a second opening degree updating range; the second opening degree update range is as follows: second to first opening values;
and the regulating module is used for regulating and controlling the proportional valve according to the second opening updating range and returning to the preset values of the acquired terminal water inlet temperature, the terminal water outlet temperature and the temperature difference so as to dynamically complete AHU control.
7. The three-point clamp adaptive AHU control system of claim 6, further comprising:
the third temperature difference determining module is used for determining a third temperature difference according to the total outlet water temperature of the machine room and the terminal inlet water temperature;
the third comparison module is used for comparing the third temperature difference with the preset temperature difference value to obtain a third comparison result;
the minimum value output module is used for outputting the minimum value of the opening range when the third comparison result shows that the first temperature difference is smaller than or equal to the preset temperature difference value;
the maximum value output module is used for outputting the maximum value of the opening range when the third comparison result shows that the third temperature difference is larger than the preset temperature difference value;
and determining the opening range of the proportional valve according to the minimum value and the maximum value.
8. A three-point clamp adaptive AHU control system, comprising: the system comprises a three-level PID controller, a proportional valve and a plurality of temperature sensors;
the temperature sensors are used for acquiring the water inlet temperature at the tail end, the water outlet temperature at the tail end and the water outlet temperature of the machine room;
the three-level PID controller is respectively connected with the proportional valve and the temperature sensor and is used for determining the opening range of the proportional valve according to the terminal water inlet temperature, the terminal water outlet temperature and the machine room water outlet temperature by adopting the control method according to any one of claims 1 to 5;
the proportional valve is arranged on the water return pipeline.
9. The three-point clamp adaptive AHU control system of claim 8, wherein the plurality of temperature sensors comprises: a total water supply temperature sensor, an inlet water temperature sensor and an outlet water temperature sensor;
the total water supply temperature sensor is arranged on a connecting pipeline between the machine room and the tail end; the water inlet temperature sensor is arranged at a water inlet at the tail end; the water outlet temperature sensor is arranged at a water outlet at the tail end.
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