A method, equipment, and storage medium for preventing backflow in a secondary pump air conditioning water system.

Abstract

This invention discloses a backflow prevention control method, device, and storage medium for a secondary pump air conditioning water system. The method includes: real-time acquisition of operating data of the secondary pump air conditioning water system, and simultaneous scanning of the two-way valve opening values ​​of all online terminal devices; constructing a terminal heat sensitivity evaluation model based on the two-way valve opening values ​​of all online terminal devices, and calculating the terminal heat sensitivity index of the current system; calculating the maximum allowable secondary side mixed water supply temperature threshold under the current operating conditions based on the terminal heat sensitivity index and the design water supply temperature; real-time monitoring of the status of the overflow and deficit pipes, and when the flow rate of the overflow and deficit pipes shows reverse flow or the forward flow rate is lower than the safety dead zone, calculating the secondary side mixed water supply temperature after backflow occurs, comparing the predicted temperature with the allowable threshold, and if it does not exceed the limit, using the thermal inertia of the pipe network to maintain the current operating state of the cold source and delaying the addition of cold source units; if it exceeds the limit or is predicted to exceed the limit, triggering the cold source unit addition procedure, significantly improving the system's energy efficiency.

Description

Technical Field

[0001] This invention relates to the field of air conditioning automation control technology, specifically to a method, equipment, and storage medium for preventing backflow in a secondary pump air conditioning water system. Background Technology

[0002] In large public buildings and industrial plants, secondary pump air conditioning water systems are widely used due to their low energy consumption and good hydraulic balance. The system decouples the primary and secondary sides through the surplus and deficit pipe. Under ideal operating conditions, the primary flow rate should be slightly greater than or equal to the secondary flow rate, and the surplus and deficit pipe should have a forward flow.

[0003] However, in actual operation, reverse mixing often occurs, that is, the secondary side demand flow is greater than the primary side flow, causing the return water to flow back into the main water supply pipe through the surplus / deficit pipe, raising the secondary side water supply temperature.

[0004] Traditional control strategies typically employ a single logic: once the flow rate in the supply and demand pipes is detected to be reversed or approaching zero, the system determines that the cooling capacity is insufficient and immediately starts the next chiller. However, this control method has the following drawbacks:

[0005] 1. During transitional seasons or under partial load conditions, the system's flow rate fluctuates significantly. If a slight backflow occurs due to short-term flow fluctuations, immediately adding a chiller will result in excess cooling capacity in the system. The chiller will then shut down due to insufficient load shortly after starting operation, severely impacting the equipment's lifespan.

[0006] 2. Backflow can cause the water supply temperature to rise, but not all terminal devices need to supply water at the set temperature. If most terminal valves are open, it means that the heat exchange capacity of the terminal is sufficient. In this case, a slight increase in water temperature will not affect indoor comfort. Blindly adding more machines will result in energy waste.

[0007] 3. Traditional strategies cannot distinguish between backflow caused by an actual increase in heat load and false high-flow backflow caused by hydraulic imbalance, often resulting in adding units without providing cooling and low energy efficiency ratio. Summary of the Invention

[0008] This invention proposes a method, equipment, and storage medium for preventing backflow in a secondary pump air conditioning water system, in order to solve the problems mentioned in the background art.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: A method for preventing backflow in a secondary pump air conditioning water system according to the present invention includes the following steps:

[0010] S1. Real-time acquisition of operating data of the secondary pump air conditioning water system, and simultaneous scanning of the two-way valve opening value of all online terminal equipment;

[0011] S2. Based on the two-way valve opening values ​​of all online terminal devices, construct a terminal heat sensitivity evaluation model and calculate the terminal heat sensitivity index of the current system.

[0012] S3. Based on the terminal heat sensitivity index and the design water supply temperature, calculate the maximum allowable secondary side mixed water supply temperature threshold under the current operating conditions.

[0013] S4. Real-time monitoring of the status of the overflow pipe. When the flow rate of the overflow pipe is shown as reverse flow or the forward flow rate is lower than the safe dead zone, the secondary side mixed water supply temperature after the reverse flow occurs is calculated or predicted in real time according to the law of conservation of energy.

[0014] S5. The secondary side mixed water supply temperature is compared with the maximum permissible secondary side mixed water supply temperature threshold in real time: when the secondary side mixed water supply temperature is not greater than the maximum permissible secondary side mixed water supply temperature threshold, the system is determined to be in a thermal inertia buffer period, the number of currently activated chillers remains unchanged, and the secondary pump frequency is locked or finely adjusted to limit the expansion of reverse flow; otherwise, the system is determined to be in a period of insufficient cooling, and the cold source addition program is immediately triggered to start the standby chiller and the corresponding primary pump.

[0015] Preferably, the operating data of the secondary pump air conditioning water system includes cold source side data, load side data, and terminal data.

[0016] Preferred,

[0017] The cold source side data includes: primary water supply temperature and total primary pump flow rate;

[0018] The load-side data includes: secondary return water temperature, total flow rate of secondary pumps, and flow rate of the surplus / deficit pipe.

[0019] The terminal data includes: the opening value of the two-way valve of all online terminal devices.

[0020] The end thermal sensitivity index The calculation method is as follows:

[0021] Set a valve high-opening threshold and count the number of terminal devices whose opening exceeds the valve high-opening threshold. Total number of online terminals The ratio:

[0022]

[0023] in, .

[0024] Preferably, in step S3, the maximum permissible secondary-side mixed water supply temperature threshold is calculated using an inverse proportional linear interpolation method:

[0025] )

[0026] in, The maximum allowable temperature drift amplitude of the system, when When it approaches 1, Approaching ;when When it approaches 0, Allows for the maximum drift amplitude.

[0027] Preferably, in step S4, the formula for calculating the secondary side mixed water supply temperature is:

[0028]

[0029] in, This is the total flow rate of the primary pump. This refers to the primary water supply temperature. Total flow rate of secondary pump This refers to the secondary side return water temperature;

[0030] When the physical temperature sensor response is delayed, the mixed water supply temperature can be quickly estimated by using the flow rate and return water temperature.

[0031] Preferably, in step S5, when determining that the system is in a thermal inertia buffer period, the remaining buffer time is calculated: based on the current rate of increase of the secondary side mixed water supply temperature, the time required for the secondary side mixed water supply temperature to reach the maximum permissible secondary side mixed water supply temperature threshold is predicted; when the remaining buffer time is less than the minimum time required for the chiller to start, the start-up signal is triggered in advance.

[0032] Preferably, in S5,

[0033] When the secondary side mixed water supply temperature is not greater than the maximum allowable secondary side mixed water supply temperature threshold, although backflow occurs, the temperature of the mixed water is still within the acceptable range at the end. At this time, the system does not add a chiller and maintains the current chiller operation. The system is determined to be in the thermal inertia buffer period, and the secondary pump frequency is locked or finely adjusted to limit the expansion of backflow.

[0034] When the secondary side mixed water supply temperature exceeds the maximum permissible secondary side mixed water supply temperature threshold, the water temperature deterioration has affected the core terminal heat exchange. At this time, the additional chiller logic is immediately triggered, and the system is determined to be in a period of insufficient cooling. The cold source additional chiller program is immediately triggered to start the standby chiller and the corresponding primary pump.

[0035] In another aspect, the present invention also discloses a computer-readable storage medium storing a computer program, which, when executed by a processor, causes the processor to perform the steps of the method described above.

[0036] In another aspect, the present invention also discloses a computer device, including a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor performs the steps of the method described above.

[0037] As can be seen from the above technical solution, the present invention provides a backflow prevention control method for a secondary pump air conditioning water system. Compared with the prior art, the present invention has the following advantages:

[0038] 1. This invention determines that the system is in a thermal inertia buffer period when the secondary side mixed water supply temperature is not greater than the maximum permissible secondary side mixed water supply temperature threshold. It keeps the number of currently running chillers unchanged and locks or fine-tunes the secondary pump frequency to limit the expansion of reverse flow. This avoids frequent start-up and shutdown of chillers caused by short-term flow fluctuations, significantly reduces the low-load operation time of chillers, and improves the overall COP of the chiller plant.

[0039] 2. This invention enables the automatic adjustment of the control strategy based on the actual load at the terminal; and fully utilizes the system's temperature drift tolerance during transitional seasons or under low load conditions to achieve flexible control.

[0040] 3. When the secondary side mixed water supply temperature exceeds the maximum permissible secondary side mixed water supply temperature threshold, the water temperature deterioration has affected the core terminal heat exchange. At this time, the additional chiller logic is immediately triggered, and the system is determined to be in a period of insufficient cooling. The cold source additional chiller program is immediately triggered to start the backup chiller and the corresponding primary pump to ensure that the chiller can be added in time when the core area needs cooling. Energy saving is achieved at non-critical times, and a balance between comfort and energy saving is achieved.

[0041] 4. This invention uses a temperature prediction algorithm to predict water temperature changes before the physical temperature sensor reacts, overcoming the lag of traditional temperature control and improving the accuracy of temperature control. Attached Figure Description

[0042] Figure 1 This is a schematic flowchart of a backflow prevention control method for a secondary pump air conditioning water system according to the present invention.

[0043] Figure 2 This is a graph showing the relationship between the terminal heat sensitivity and the allowable water supply temperature according to the present invention.

[0044] Figure 3 This is a schematic diagram of the sensor arrangement and data flow direction of the secondary pump air conditioning water system of the present invention. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0046] like Figure 1 As shown in the figure, a backflow prevention control method for a secondary pump air conditioning water system in this embodiment includes the following steps:

[0047] S1. Real-time acquisition of operating data of the secondary pump air conditioning water system, and simultaneous scanning of the two-way valve opening value of all online terminal equipment;

[0048] S2. Based on the two-way valve opening values ​​of all online terminal devices, construct a terminal heat sensitivity evaluation model and calculate the terminal heat sensitivity index of the current system.

[0049] S3. Based on the terminal heat sensitivity index and combined with the design water supply temperature, calculate the maximum allowable secondary side mixed water supply temperature threshold under the current operating conditions.

[0050] S4. Real-time monitoring of the status of the overflow pipe. When the flow rate of the overflow pipe is shown as reverse flow or the forward flow rate is lower than the safe dead zone, the secondary side mixed water supply temperature after the reverse flow occurs is calculated or predicted in real time according to the law of conservation of energy.

[0051] S5. The secondary side mixed water supply temperature is compared with the maximum permissible secondary side mixed water supply temperature threshold in real time: when the secondary side mixed water supply temperature is not greater than the maximum permissible secondary side mixed water supply temperature threshold, the system is determined to be in a thermal inertia buffer period, the number of currently activated chillers remains unchanged, and the secondary pump frequency is locked or finely adjusted to limit the expansion of reverse flow; otherwise, the system is determined to be in a period of insufficient cooling, and the cold source addition program is immediately triggered to start the standby chiller and the corresponding primary pump.

[0052] Furthermore, the operating data of the secondary pump air conditioning water system includes data from the cold source side, load side, and terminal data.

[0053] Furthermore,

[0054] The data on the cold source side includes: primary water supply temperature and total flow rate of the primary pump;

[0055] Load-side data includes: secondary return water temperature, total flow rate of secondary pumps, and flow rate of the surplus / deficit pipe;

[0056] The terminal data includes: the opening value of the two-way valves of all online terminal devices.

[0057] Furthermore, the terminal thermal sensitivity index The calculation method is as follows:

[0058] Set a valve high-opening threshold and count the number of terminal devices whose opening exceeds the valve high-opening threshold. Total number of online terminals The ratio:

[0059]

[0060] in, .

[0061] Furthermore, in S3, the maximum permissible secondary side mixed water supply temperature threshold is calculated using an inverse proportional linear interpolation method:

[0062] )

[0063] in, The maximum allowable temperature drift amplitude of the system, when When it approaches 1, Approaching ;when When it approaches 0, Allows for the maximum drift amplitude.

[0064] Furthermore, in S4, the formula for calculating the secondary side mixed water supply temperature is:

[0065]

[0066] in, This is the total flow rate of the primary pump. This refers to the primary water supply temperature. Total flow rate of secondary pump This refers to the secondary side return water temperature;

[0067] Based on the secondary side mixed water supply temperature, when the physical temperature sensor response is lagging, the mixed water supply temperature can be quickly estimated by using flow rate and return water temperature.

[0068] Furthermore, in S5, when determining that the system is in the thermal inertia buffer period, it also includes calculating the remaining buffer time: based on the current rate of increase of the secondary side mixed water supply temperature, predicting the time required for the secondary side mixed water supply temperature to reach the maximum permissible secondary side mixed water supply temperature threshold; when the remaining buffer time is less than the minimum time required for the chiller to start, triggering the start-up signal in advance.

[0069] Furthermore, in S5,

[0070] When the secondary side mixed water supply temperature is not greater than the maximum allowable secondary side mixed water supply temperature threshold, although backflow occurs, the temperature of the mixed water is still within the acceptable range at the end. At this time, the system does not add a chiller and maintains the current chiller operation. The system is determined to be in the thermal inertia buffer period, and the secondary pump frequency is locked or finely adjusted to limit the expansion of backflow.

[0071] When the secondary side mixed water supply temperature exceeds the maximum permissible secondary side mixed water supply temperature threshold, the water temperature deterioration has affected the core terminal heat exchange. At this time, the additional chiller logic is immediately triggered, and the system is determined to be in a period of insufficient cooling. The cold source additional chiller program is immediately triggered to start the standby chiller and the corresponding primary pump.

[0072] In practical applications, taking the secondary pump air conditioning water system of a large factory as an example, the implementation steps are as follows:

[0073] Step 1: System Initialization: Set the design water supply temperature =7℃, maximum permissible temperature drift =1.0℃, valve high opening threshold =90%.

[0074] Step 2, Data Acquisition: The BAS system collects data every 30 seconds; assuming current operating conditions: two chillers are running, and the total primary flow rate... =1000m³ / h, primary water supply temperature =7℃. Total secondary flow rate =Suddenly increased to 1100 m³ / h, with a reverse flow of 100 m³ / h appearing in the overflow / deficit pipe. Secondary side return water temperature =12℃.

[0075] Step 3: Sensitivity Assessment: The system scanned 100 AHUs at the end of the line and found that only 10 AHUs had a two-way valve opening exceeding 90%. The sensitivity index was calculated. =10 / 100=0.1. This indicates that the load at most of the system's terminals is low, and the heat exchange coils have a large margin.

[0076] Step 4, Threshold Calculation: According to the formula =7+1.0×(1-0.1)=7.9℃, meaning that under the current operating conditions, the maximum allowable temperature of the secondary water supply is 7.9℃.

[0077] Step 5, Countercurrent Temperature Prediction: Calculate the mixed water supply temperature. ℃.

[0078] Step Six: Comparison and Discovery =7.45℃< =7.9℃; Conclusion: No additional equipment is required; Although backflow occurred, the mixed water temperature of 7.45℃ is still lower than the allowable 7.9℃, and most of the terminal valves have small openings, which can be fully compensated for by automatically increasing the valve openings.

[0079] Step 7: Keep the two existing chillers running. The BAS monitoring interface will display "Entering temperature drift buffer mode," and continue monitoring. Changes; if subsequent Continued increase leads to Temperatures exceeding 7.9℃ may be due to the excessive opening of end valves. Increased thus lowered Then add more machines.

[0080] In another aspect, the present invention also discloses a computer-readable storage medium storing a computer program, which, when executed by a processor, causes the processor to perform the steps of the method described above.

[0081] In another aspect, the present invention also discloses a computer device, including a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor performs the steps of the method described above.

[0082] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. A computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the flow or function according to the embodiments of this application is generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., solid-state disk), etc.

[0083] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0084] The various embodiments in this specification are described in a related manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions of the method embodiments.

[0085] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preventing backflow in a secondary pump air conditioning water system, characterized in that, Includes the following steps: S1. Real-time acquisition of operating data of the secondary pump air conditioning water system, and simultaneous scanning of the two-way valve opening value of all online terminal equipment; S2. Based on the two-way valve opening values ​​of all online terminal devices, construct a terminal heat sensitivity evaluation model and calculate the terminal heat sensitivity index of the current system. S3. Based on the terminal heat sensitivity index and the design water supply temperature, calculate the maximum allowable secondary side mixed water supply temperature threshold under the current operating conditions. S4. Monitor the status of the overflow pipe in real time. When the flow rate of the overflow pipe is shown as reverse flow or the forward flow rate is lower than the safe dead zone, calculate the secondary side mixed water supply temperature after the reverse flow occurs in real time. S5. The secondary side mixed water supply temperature is compared with the maximum permissible secondary side mixed water supply temperature threshold in real time: when the secondary side mixed water supply temperature is not greater than the maximum permissible secondary side mixed water supply temperature threshold, the system is determined to be in a thermal inertia buffer period, the number of currently activated chillers remains unchanged, and the secondary pump frequency is locked or finely adjusted to limit the expansion of reverse flow; otherwise, the system is determined to be in a period of insufficient cooling, and the cold source addition program is immediately triggered to start the standby chiller and the corresponding primary pump.

2. The backflow prevention control method for a secondary pump air conditioning water system according to claim 1, characterized in that: The operating data of the secondary pump air conditioning water system includes cold source side data, load side data, and terminal data.

3. The backflow prevention control method for a secondary pump air conditioning water system according to claim 2, characterized in that: The cold source side data includes: primary water supply temperature and total primary pump flow rate; The load-side data includes: secondary return water temperature, total flow rate of secondary pumps, and flow rate of the surplus / deficit pipe. The terminal data includes: the opening value of the two-way valve of all online terminal devices.

4. The backflow prevention control method for a secondary pump air conditioning water system according to claim 3, characterized in that: The end thermal sensitivity index The calculation method is as follows: Set a valve high-opening threshold and count the number of terminal devices whose opening exceeds the valve high-opening threshold. Total number of online terminals The ratio: in, .

5. The backflow prevention control method for a secondary pump air conditioning water system according to claim 4, characterized in that: In step S3, the maximum permissible secondary side mixed water supply temperature threshold is calculated using an inverse proportional linear interpolation method: ) in, The maximum allowable temperature drift amplitude of the system, when When it approaches 1, Approaching ;when When it approaches 0, Allows for the maximum drift.

6. The backflow prevention control method for a secondary pump air conditioning water system according to claim 5, characterized in that: In step S4, the formula for calculating the secondary side mixed water supply temperature is: in, This is the total flow rate of the primary pump. This refers to the primary water supply temperature. Total flow rate of secondary pump This refers to the secondary side return water temperature; When the physical temperature sensor response is delayed, the mixed water supply temperature can be quickly estimated by using the flow rate and return water temperature.

7. The backflow prevention control method for a secondary pump air conditioning water system according to claim 6, characterized in that: In step S5, when the system is determined to be in a thermal inertia buffer period, the remaining buffer time is calculated: based on the current rate of increase of the secondary side mixed water supply temperature, the time required for the secondary side mixed water supply temperature to reach the maximum permissible secondary side mixed water supply temperature threshold is predicted; when the remaining buffer time is less than the minimum time required for the chiller to start, the start-up signal is triggered in advance.

8. The backflow prevention control method for a secondary pump air conditioning water system according to claim 7, characterized in that: In S5, When the secondary side mixed water supply temperature is not greater than the maximum allowable secondary side mixed water supply temperature threshold, although backflow occurs, the temperature of the mixed water is still within the acceptable range at the end. At this time, the system does not add a chiller and maintains the current chiller operation. The system is determined to be in the thermal inertia buffer period, and the secondary pump frequency is locked or finely adjusted to limit the expansion of backflow. When the secondary side mixed water supply temperature exceeds the maximum permissible secondary side mixed water supply temperature threshold, the water temperature deterioration has affected the core terminal heat exchange. At this time, the additional chiller logic is immediately triggered, and the system is determined to be in a period of insufficient cooling. The cold source additional chiller program is immediately triggered to start the standby chiller and the corresponding primary pump.

9. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by a processor, it causes the processor to perform the steps of the method as described in any one of claims 1 to 8.

10. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the computer program is executed by the processor, it causes the processor to perform the steps of the method as described in any one of claims 1 to 8.

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