Central air conditioning cooling water supply and return water temperature difference optimization control system and method

Abstract

The present application relates to a kind of central air conditioning cooling water supply and return water temperature difference optimization control system and method, including by cooling tower, the cooling water pump being equipped with frequency converter, cooling water pump, cooling water machine group condenser sequentially connected and formed water circuit and for controlling supply and return water temperature difference controller, cooling tower and cooling water pump between and cooling water pump and cooling water machine group condenser between by return water pipe communication, cooling water machine group condenser and cooling tower between by water supply pipe communication, return water pipe and water supply pipe are respectively provided with first temperature sensor and second temperature sensor, frequency converter, first temperature sensor and second temperature sensor are electrically connected with controller respectively.By respectively collecting water supply temperature signal and return water temperature signal, the optimized temperature difference set value is calculated by controller, and the working frequency of frequency converter is calculated, to control the rotating speed of cooling water pump, the temperature difference between water supply temperature and return water temperature is dynamically adjusted to optimized temperature difference set value, improve the accuracy and reliability of temperature difference set value calculation.

Description

Technical Field

[0001] This invention relates to the field of building energy conservation and refrigeration and air conditioning control technology, and in particular to a central air conditioning cooling water supply and return water temperature difference optimization control system and control method. Background Technology

[0002] Central air conditioning systems operate under partial load most of the time, and the cooling water system's flow rate is mostly in surplus. Implementing variable flow control for the cooling water system can effectively reduce the energy consumption of the cooling water pumps. Variable flow control for cooling water systems typically uses temperature difference control, adjusting the operating frequency of the cooling water pumps based on the temperature difference between the supply and return water. This temperature difference is generally maintained at 4℃-5℃. The design temperature for the cooling water return is usually 32℃, and the design temperature for the supply is 37℃. When the outdoor temperature is high, the cooling water return temperature often exceeds the design temperature of 32℃. Maintaining this temperature difference at a fixed 5℃ will cause the cooling water supply temperature to exceed 37℃, even reaching 40℃. This not only reduces the operating efficiency of the chiller unit but also triggers a high-temperature alarm, leading to chiller shutdown. This not only affects the cooling effect of the system but also poses a significant safety hazard. In practical engineering applications, to ensure the safe operation of the chiller unit, many engineers often use low temperature difference setpoints (such as 3℃) for cooling water pump control, significantly increasing the energy waste of the cooling water pumps. Therefore, optimizing the temperature difference control strategy of the central air conditioning cooling water system is of great significance for improving the safety of the central air conditioning system operation and reducing the system's energy consumption.

[0003] Given the aforementioned technical background, the existing central air conditioning cooling water pump frequency conversion control system has a fixed temperature difference. When the outdoor temperature is high, the cooling water supply temperature is too high, causing the chiller unit to experience high temperature alarm and shutdown. This not only affects the energy-saving operation of the system but also poses a significant safety hazard, failing to fully meet the needs of building safety and energy conservation. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the shortcomings of the prior art by providing a central air conditioning cooling water supply and return water temperature difference optimization control system and method. This control system and method can optimize the supply and return water temperature difference setpoint in real time as the cooling water supply and return water temperatures change, while ensuring the safe and stable operation of the system and meeting the user's cooling capacity requirements, thereby maximizing the saving of system operating energy consumption.

[0005] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: A central air conditioning cooling water supply and return water temperature difference optimization control system, comprising a water circuit formed by sequentially connecting a cooling tower, a cooling water pump equipped with a frequency converter, and a chiller condenser, and a controller for controlling the supply and return water temperature difference, wherein the cooling tower and the cooling water pump and the cooling water pump and the chiller condenser are connected through a return water pipe, and the chiller condenser and the cooling tower are connected through a supply water pipe, wherein a first temperature sensor and a second temperature sensor are respectively installed on the return water pipe and the supply water pipe, and the frequency converter, the first temperature sensor and the second temperature sensor are electrically connected to the controller;

[0006] The first temperature sensor and the second temperature sensor are used to collect the water supply temperature signal and the return water temperature signal in the water supply pipe, respectively.

[0007] The controller is used to calculate an optimized temperature difference setpoint based on the supply water temperature signal and the return water temperature signal, calculate the real-time cooling water supply and return water temperature difference based on the supply water temperature signal and the return water temperature signal, determine whether the cooling water supply and return water temperature difference is within the deviation range of the optimized temperature difference setpoint, if so, control the operating frequency of the cooling water pump to maintain the previous output value unchanged, otherwise compare the cooling water supply and return water temperature difference with the optimized temperature difference setpoint, calculate the operating frequency of the frequency converter, and output it to the frequency converter;

[0008] The frequency converter controls the speed of the cooling water pump according to the operating frequency, and adjusts the temperature difference between the temperature of the water supplied in the return water pipe and the temperature of the water supplied in the supply water pipe to the optimized temperature difference setting value.

[0009] The beneficial effects of this invention are as follows: The central air conditioning cooling water supply and return water temperature difference optimization control system of this invention collects supply water temperature signals and return water temperature signals through the first temperature sensor and the second temperature sensor, respectively. The controller calculates the optimized temperature difference setpoint and further calculates the operating frequency of the inverter, thereby controlling the speed of the cooling water pump. This dynamically adjusts the temperature difference between the supply water temperature in the return water pipe and the supply water temperature in the supply water pipe to the optimized temperature difference setpoint, improving the accuracy and reliability of the temperature difference setpoint calculation. The optimized temperature difference setpoint of the cooling water supply and return water can be automatically adjusted according to the real-time changes in the cooling water supply and return water temperatures, improving the automation level of the entire system, reducing the system's response time to environmental changes, ensuring the safe and stable operation of the system, and reducing system energy consumption, thus achieving energy-saving operation of the central air conditioning cooling water system.

[0010] Based on the above technical solution, the present invention can be further improved as follows:

[0011] Further: The controller calculates and optimizes the temperature difference setpoint based on the supply water temperature signal and the return water temperature signal as follows:

[0012] If we define T2 as the real-time cooling water supply temperature and T1 as the real-time cooling water return temperature... To optimize the temperature difference setpoint, ΔT set The default temperature difference setting, T 2，up The upper limit of the set cooling water supply temperature shall not exceed the high temperature alarm temperature;

[0013] The formula for calculating the optimized temperature difference setpoint is:

[0014] If T2 > T 2，up ,but

[0015] If T2≤T 2，up And T1+ΔT set >T 2，up ,but

[0016] If T2≤T 2，up And T1+ΔT set ≤T 2，up ,but

[0017] The beneficial effect of the above further solution is that when the real-time cooling water supply temperature T2 is higher than the set upper limit value T of the cooling water supply temperature... 2，up At the same time, optimize the temperature difference setpoint. The temperature difference setpoint changes with the real-time cooling water return temperature T1. As the real-time cooling water return temperature T1 increases, the temperature difference setpoint is optimized. The real-time cooling water return temperature T1 is reduced, and the temperature difference setpoint is optimized. Increase; when the real-time cooling water supply temperature T2 is less than or equal to the set upper limit value of the cooling water supply temperature T 2，up At this point, further judgment is needed. If the real-time cooling water return temperature T1 differs from the default temperature difference setting ΔT... set The sum of these values ​​is greater than the set upper limit value T for cooling water supply temperature. 2，up At the same time, optimize the temperature difference setpoint. Similarly, the upper limit value T for the cooling water supply temperature is set. 2，up The difference between the real-time cooling water return temperature T1 and the default temperature difference setting ΔT. set The sum is less than or equal to the upper limit value T of the set cooling water supply temperature. 2，up At the same time, optimize the temperature difference setpoint. The default temperature difference setting value ΔT set .

[0018] Further: The range of the optimized temperature difference setting value is between the upper limit of the temperature difference and the lower limit of the temperature difference. When the optimized temperature difference setting value calculated by the controller is greater than the upper limit of the temperature difference, it is determined that the optimized temperature difference setting value is equal to the upper limit of the temperature difference. When the optimized temperature difference setting value calculated by the controller is less than the lower limit of the temperature difference, it is determined that the optimized temperature difference setting value is equal to the lower limit of the temperature difference.

[0019] The beneficial effect of the above-mentioned further solution is that by controlling the upper limit to the lower limit of the optimized temperature difference setpoint, a certain safety margin can be left, thus ensuring the safety and stability of the entire system.

[0020] This invention also provides a method for optimizing the temperature difference control of cooling water supply and return water in a central air conditioning system. The method, employing the aforementioned optimized temperature difference control system for cooling water supply and return water in a central air conditioning system, includes the following steps:

[0021] The supply water temperature signal and the return water temperature signal in the supply water pipe are collected respectively.

[0022] The optimized temperature difference setpoint is calculated based on the supply water temperature signal and the return water temperature signal.

[0023] The real-time cooling water supply and return water temperature difference is calculated based on the supply water temperature signal and return water temperature signal. It is determined whether the cooling water supply and return water temperature difference is within the deviation range of the optimized temperature difference setting value. If it is, the operating frequency of the cooling water pump is controlled to remain unchanged from the previous output value. Otherwise, the cooling water supply and return water temperature difference is compared with the optimized temperature difference setting value to determine the operating frequency of the frequency converter.

[0024] The frequency converter controls the speed of the cooling water pump according to the operating frequency and adjusts the temperature difference between the temperature of the water supplied in the return water pipe and the temperature of the water supplied in the supply water pipe to the optimized temperature difference setting value.

[0025] The central air conditioning cooling water supply and return water temperature difference optimization control method of the present invention collects supply water temperature signals and return water temperature signals respectively, calculates an optimized temperature difference setpoint, and further calculates the operating frequency of the inverter, thereby controlling the speed of the cooling water pump. This dynamically adjusts the temperature difference between the supply water temperature in the return water pipe and the supply water temperature in the supply water pipe to the optimized temperature difference setpoint, improving the accuracy and reliability of the temperature difference setpoint calculation. The optimized temperature difference setpoint of the cooling water supply and return water can be automatically adjusted according to the real-time changes in the cooling water supply and return water temperatures, improving the automation level of the entire system, reducing the system's response time to environmental changes, ensuring the safe and stable operation of the system, and reducing system energy consumption, thus achieving energy-saving operation of the central air conditioning cooling water system.

[0026] Based on the above technical solution, the present invention can be further improved as follows:

[0027] Further: The step of calculating and optimizing the temperature difference setpoint based on the supply water temperature signal and the return water temperature signal specifically includes the following steps:

[0028] If we define T2 as the real-time cooling water supply temperature and T1 as the real-time cooling water return temperature... To optimize the temperature difference setpoint, ΔT set The default temperature difference setting, T 2，up The upper limit of the set cooling water supply temperature shall not exceed the high temperature alarm temperature;

[0029] The formula for calculating the optimized temperature difference setpoint is:

[0030] If T2 > T 2，up ,but

[0031] If T2≤T 2，up And T1+ΔT set ≥T 2，up ,but

[0032] If T2≤T 2，up And T1+ΔT set ≤T 2，up ,but

[0033] The beneficial effect of the above further solution is that when the real-time cooling water supply temperature T2 is higher than the set upper limit value T of the cooling water supply temperature... 2，up At the same time, optimize the temperature difference setpoint. The temperature difference setpoint changes with the real-time cooling water return temperature T1. As the real-time cooling water return temperature T1 increases, the temperature difference setpoint is optimized. The real-time cooling water return temperature T1 is reduced, and the temperature difference setpoint is optimized. Increase; when the real-time cooling water supply temperature T2 is less than or equal to the set upper limit value of the cooling water supply temperature T 2，up At this point, further judgment is needed. If the real-time cooling water return temperature T1 differs from the default temperature difference setting ΔT... set The sum of these values ​​is greater than the set upper limit value T for cooling water supply temperature. 2，up At the same time, optimize the temperature difference setpoint. Similarly, the upper limit value T for the cooling water supply temperature is set. 2，up The difference between the real-time cooling water return temperature T1 and the default temperature difference setting ΔT. set The sum is less than or equal to the upper limit value T of the set cooling water supply temperature. 2，up At the same time, optimize the temperature difference setpoint. The default temperature difference setting value ΔT set .

[0034] Further: The range of the optimized temperature difference setting value is between the upper limit of the temperature difference and the lower limit of the temperature difference. When the optimized temperature difference setting value calculated by the controller is greater than the upper limit of the temperature difference, it is determined that the optimized temperature difference setting value is equal to the upper limit of the temperature difference. When the optimized temperature difference setting value calculated by the controller is less than the lower limit of the temperature difference, it is determined that the optimized temperature difference setting value is equal to the lower limit of the temperature difference.

[0035] The beneficial effect of the above-mentioned further solution is that by controlling the upper limit of the temperature difference to the lower limit of the temperature difference setpoint, a certain safety margin can be left, which can ensure the safety and stability of the entire system.

[0036] The present invention also provides a computer-readable storage medium storing computer instructions, which are used to cause a processor to execute the aforementioned method for optimizing the temperature difference between the supply and return cooling water of a central air conditioning system.

[0037] The present invention also provides a central air conditioning cooling water supply and return water temperature difference optimization control device, the central air conditioning cooling water supply and return water temperature difference optimization control device comprising:

[0038] At least one processor and a storage medium, wherein the memory is communicatively connected to the processor;

[0039] The storage medium stores a computer program that can be executed by the at least one processor, and the computer program is executed by the at least one processor to enable the at least one processor to execute the central air conditioning cooling water supply and return water temperature difference optimization control method. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the structure of a central air conditioning cooling water supply and return water temperature difference optimization control system according to an embodiment of the present invention;

[0041] Figure 2 This is a diagram illustrating the optimized temperature difference limitation range according to an embodiment of the present invention;

[0042] Figure 3 This is a flowchart illustrating a method for optimizing the temperature difference between the supply and return cooling water of a central air conditioning system, according to an embodiment of the present invention.

[0043] The attached diagram lists the components represented by each number as follows:

[0044] 1. Cooling tower; 2. Return water pipe; 3. Cooling water pump; 4. Chiller condenser; 5. Water supply pipe; 6. Frequency converter; 7. Controller; 8. First temperature sensor; 9. Second temperature sensor. Detailed Implementation

[0045] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0046] like Figure 1 As shown, a central air conditioning cooling water supply and return water temperature difference optimization control system includes a water circuit formed by sequentially connecting a cooling tower 1, a cooling water pump 3 equipped with a frequency converter 6, and a chiller condenser 4, and a controller 7 for controlling the supply and return water temperature difference. The cooling tower 1 and the cooling water pump 3, as well as the cooling water pump 3 and the chiller condenser 4, are connected through a return water pipe 2. The chiller condenser 4 and the cooling tower 1 are connected through a supply water pipe 5. A first temperature sensor 8 and a second temperature sensor 9 are respectively installed on the return water pipe 2 and the supply water pipe 5. The frequency converter 6, the first temperature sensor 8, and the second temperature sensor 9 are electrically connected to the controller 7.

[0047] The first temperature sensor 8 and the second temperature sensor 9 are used to collect the water supply temperature signal in the return water pipe 2 and the return water temperature signal in the water supply pipe 5, respectively.

[0048] The controller 7 is used to calculate an optimized temperature difference setpoint based on the supply water temperature signal and the return water temperature signal, and to calculate the operating frequency of the inverter 6 based on the optimized temperature difference setpoint.

[0049] The frequency converter 6 controls the speed of the cooling water pump 3 according to the operating frequency, and adjusts the temperature difference between the water temperature in the return water pipe 2 and the water temperature in the supply water pipe 5 to the optimized temperature difference setting value.

[0050] The central air conditioning cooling water supply and return water temperature difference optimization control system of the present invention collects supply water temperature signals and return water temperature signals through the first temperature sensor 8 and the second temperature sensor 9, respectively. The controller 7 calculates the optimized temperature difference setpoint and further calculates the operating frequency of the inverter 6, thereby controlling the speed of the cooling water pump 3 to dynamically adjust the temperature difference between the supply water temperature in the return water pipe 2 and the supply water temperature in the supply water pipe 5 to the optimized temperature difference setpoint. This improves the accuracy and reliability of the temperature difference setpoint calculation. The optimized temperature difference setpoint of the cooling water supply and return water can be automatically adjusted according to the real-time changes in the cooling water supply and return water temperatures, improving the automation level of the entire system, reducing the system's response time to environmental changes, ensuring the safe and stable operation of the system, and reducing system energy consumption, thus achieving energy-saving operation of the central air conditioning cooling water system.

[0051] Here, the frequency converter 6 sets the frequency according to the calculated working frequency value, adjusts the speed of the cooling water pump 3, and then adjusts the temperature difference between the water supply pipe 5 and the return pipe 2 to maintain it at the optimized temperature difference setting value. This ensures that the cooling water supply temperature is always lower than the high temperature alarm temperature of the chiller unit, thereby ensuring the safe operation of the chiller unit. At the same time, the cooling water pump 3 operates within the safe range with the lowest energy consumption, thus saving energy.

[0052] In one or more embodiments of the present invention, the controller 7 includes a computing module and a frequency conversion control module;

[0053] The calculation module is used to calculate and optimize the temperature difference setpoint based on the supply water temperature signal and the return water temperature signal, and transmit it to the frequency converter control module.

[0054] The variable frequency control module is used to calculate the real-time cooling water supply and return water temperature difference based on the supply water temperature signal and the return water temperature signal, and to determine whether the cooling water supply and return water temperature difference is within the deviation range of the optimized temperature difference setting value. If it is, the module controls the operating frequency of the cooling water pump 3 to remain unchanged from the previous output value. Otherwise, the module compares the cooling water supply and return water temperature difference with the optimized temperature difference setting value, calculates the operating frequency of the frequency converter 6, and outputs it to the frequency converter 6.

[0055] The calculation module calculates the optimized temperature difference setpoint based on the supply water temperature signal and the return water temperature signal. Then, the frequency converter control module calculates the real-time cooling water supply and return water temperature difference based on the supply water temperature signal and the return water temperature signal. The real-time cooling water supply and return water temperature difference can be compared with the optimized temperature difference setpoint to accurately calculate the operating frequency of the frequency converter 6. This allows control of the speed of the cooling water pump 3, thus conveniently and dynamically adjusting the cooling water supply and return water temperature difference to the optimized temperature difference setpoint.

[0056] In one or more embodiments of the present invention, the controller 7 calculates and optimizes the temperature difference setpoint based on the supply water temperature signal and the return water temperature signal as follows:

[0057] If we define T2 as the real-time cooling water supply temperature and T1 as the real-time cooling water return temperature... To optimize the temperature difference setpoint, ΔT set The default temperature difference setting, T 2，up The upper limit of the set cooling water supply temperature shall not exceed the high temperature alarm temperature;

[0058] The formula for calculating the optimized temperature difference setpoint is:

[0059] If T2 > T 2，up ,but

[0060] If T2≤T 2，up And T1+ΔT set >T 2，up ,but

[0061] If T2≤T 2，up And T1+ΔT set ≤T 2，up ,but

[0062] When the real-time cooling water supply temperature T2 is higher than the set upper limit value of the cooling water supply temperature T 2，up At the same time, optimize the temperature difference setpoint. The temperature difference setpoint changes with the real-time cooling water return temperature T1. As the real-time cooling water return temperature T1 increases, the temperature difference setpoint is optimized. The real-time cooling water return temperature T1 is reduced, and the temperature difference setpoint is optimized. Increase; when the real-time cooling water supply temperature T2 is less than or equal to the set upper limit value of the cooling water supply temperature T 2，up At this point, further judgment is needed. If the real-time cooling water return temperature T1 differs from the default temperature difference setting ΔT... set The sum of these values ​​is greater than the set upper limit value T for cooling water supply temperature. 2，up At the same time, optimize the temperature difference setpoint. Similarly, the upper limit value T for the cooling water supply temperature is set. 2，up The difference between the real-time cooling water return temperature T1 and the default temperature difference setting ΔT. set The sum is less than or equal to the upper limit value T of the set cooling water supply temperature. 2，up At the same time, optimize the temperature difference setpoint. The default temperature difference setting value ΔT set .

[0063] In practice, the default temperature difference setting is generally 5℃, and the high-temperature alarm temperature is generally above 38℃. To leave a certain safety margin, the T value in the algorithm of this invention... 2，up The default setting is 37.5℃. By calculating according to the above algorithm model, the optimized temperature difference setting value can be obtained.

[0064] In order to adjust the temperature difference between the water supply temperatures to the optimized temperature difference setpoint, in this embodiment of the invention, a PID algorithm is used to calculate the operating frequency of the frequency converter 6.

[0065] In one or more embodiments of the present invention, the range of the optimized temperature difference setpoint is between an upper temperature difference limit and a lower temperature difference limit. When the optimized temperature difference setpoint calculated by the controller 7 is greater than the upper temperature difference limit, it is determined that the optimized temperature difference setpoint is equal to the upper temperature difference limit. When the optimized temperature difference setpoint calculated by the controller 7 is less than the lower temperature difference limit, it is determined that the optimized temperature difference setpoint is equal to the lower temperature difference limit. By controlling the upper temperature difference to the lower temperature difference limit of the optimized temperature difference setpoint, a certain safety margin can be provided, thus ensuring the safety and stability of the entire system. In the embodiments of the present invention, the upper temperature difference limit is 5℃-7℃; the lower temperature difference limit is 2℃-3℃.

[0066] like Figure 2 As shown, a method for optimizing the temperature difference between the supply and return water of a central air conditioning system, employing the aforementioned optimized control system for the temperature difference between the supply and return water of a central air conditioning system, includes the following steps:

[0067] S1: Collect the water supply temperature signal in the return water pipe 2 and the return water temperature signal in the water supply pipe 5 respectively;

[0068] S2: Calculate and optimize the temperature difference setpoint based on the supply water temperature signal and the return water temperature signal;

[0069] S3: Calculate the real-time cooling water supply and return water temperature difference based on the supply water temperature signal and return water temperature signal, determine whether the cooling water supply and return water temperature difference is within the deviation range of the optimized temperature difference setting value, if so, control the operating frequency of the cooling water pump 3 to maintain the previous output value unchanged, otherwise compare the cooling water supply and return water temperature difference with the optimized temperature difference setting value to determine the operating frequency of the frequency converter 6.

[0070] S4: The frequency converter 6 controls the speed of the cooling water pump 3 according to the operating frequency, and adjusts the temperature difference between the water temperature in the return water pipe 2 and the water temperature in the supply water pipe 5 to the optimized temperature difference setting value.

[0071] The central air conditioning cooling water supply and return water temperature difference optimization control method of the present invention collects supply water temperature signals and return water temperature signals respectively, calculates an optimized temperature difference setpoint, and further calculates the operating frequency of the inverter 6, thereby controlling the speed of the cooling water pump 3. This dynamically adjusts the temperature difference between the supply water temperature in the return water pipe 2 and the supply water temperature in the supply water pipe 5 to the optimized temperature difference setpoint, improving the accuracy and reliability of the temperature difference setpoint calculation. The optimized temperature difference setpoint of the cooling water supply and return water can be automatically adjusted according to the real-time changes in the cooling water supply and return water temperatures, improving the automation level of the entire system, reducing the system's response time to environmental changes, ensuring the safe and stable operation of the system, and reducing system energy consumption, thus achieving energy-saving operation of the central air conditioning cooling water system.

[0072] In one or more embodiments of the present invention, the deviation range of the optimized temperature difference setpoint is between ±0.2°C of the optimized temperature difference setpoint.

[0073] In one or more embodiments of the present invention, the step of calculating the optimized temperature difference setpoint based on the supply water temperature signal and the return water temperature signal specifically includes the following steps:

[0074] If we define T2 as the real-time cooling water supply temperature and T1 as the real-time cooling water return temperature... To optimize the temperature difference setpoint, ΔT set The default temperature difference setting, T 2，up The upper limit of the set cooling water supply temperature shall not exceed the high temperature alarm temperature;

[0075] The formula for calculating the optimized temperature difference setpoint is:

[0076] If T2 > T 2，up ,but

[0077] If T2≤T 2，up And T1+ΔT set >T 2，up ,but

[0078] If T2≤T 2，up And T1+ΔT set ≤T 2，up ,but

[0079] When the real-time cooling water supply temperature T2 is higher than the set upper limit value of the cooling water supply temperature T 2，up At the same time, optimize the temperature difference setpoint. The temperature difference setpoint changes with the real-time cooling water return temperature T1. As the real-time cooling water return temperature T1 increases, the temperature difference setpoint is optimized. The real-time cooling water return temperature T1 is reduced, and the temperature difference setpoint is optimized. Increase; when the real-time cooling water supply temperature T2 is less than or equal to the set upper limit value of the cooling water supply temperature T 2，up At this point, further judgment is needed. If the real-time cooling water return temperature T1 differs from the default temperature difference setting ΔT... set The sum of these values ​​is greater than the set upper limit value T for cooling water supply temperature. 2，up At the same time, optimize the temperature difference setpoint. Similarly, the upper limit value T for the cooling water supply temperature is set. 2，up The difference between the real-time cooling water return temperature T1 and the default temperature difference setting ΔT. set The sum is less than or equal to the upper limit value T of the set cooling water supply temperature. 2，up At the same time, optimize the temperature difference setpoint. The default temperature difference setting value ΔT set .

[0080] In one or more embodiments of the present invention, the range of the optimized temperature difference setpoint is between an upper temperature difference limit and a lower temperature difference limit. When the optimized temperature difference setpoint calculated by the controller 7 is greater than the upper temperature difference limit, it is determined that the optimized temperature difference setpoint is equal to the upper temperature difference limit. When the optimized temperature difference setpoint calculated by the controller 7 is less than the lower temperature difference limit, it is determined that the optimized temperature difference setpoint is equal to the lower temperature difference limit. By controlling the upper temperature difference to the lower temperature difference limit of the optimized temperature difference setpoint, a certain safety margin can be provided, thus ensuring the safety and stability of the entire system.

[0081] For example, the optimized temperature difference setting value has a certain range. When the calculated optimized temperature difference setting value is higher than the set upper limit value, such as 7℃, the optimized temperature difference setting value is output at the upper limit value; when the calculated optimized temperature difference setting value is lower than the set lower limit value, such as 2℃, the optimized temperature difference setting value is output at the lower limit value.

[0082] In an embodiment of the present invention, the temperature difference between the cooling water supply and return water is compared with the optimized temperature difference setpoint to determine the operating frequency of the inverter 6 using a PID algorithm. Specifically:

[0083] When the real-time cooling water supply and return temperature difference is greater than the calculated optimized temperature difference setpoint, the PID algorithm calculates a larger optimized operating frequency value for the cooling water pump 3 based on the deviation value, and then sends the operating frequency signal to the frequency converter 6 to increase the speed of the cooling water pump 3, thereby reducing the cooling water supply and return temperature difference; when the real-time cooling water supply and return temperature difference is less than the calculated optimized temperature difference setpoint, the PID algorithm calculates a smaller optimized operating frequency value for the cooling water pump 3 based on the deviation value, and then sends the optimized operating frequency signal to the frequency converter 6 to decrease the speed of the cooling water pump 3, thereby increasing the cooling water supply and return temperature difference.

[0084] In the process control algorithm, a frequency control dead zone is set. The dead zone range is generally from -0.2℃ to 0.2℃. That is, when the detected temperature difference between the cooling water supply and return water deviates from the optimized temperature difference set value between -0.2℃ and 0.2℃, the PID algorithm does not perform calculations. At this time, the operating frequency of the cooling water pump 3 remains unchanged from the previous moment.

[0085] The PID algorithm used in the process control algorithm of this invention is a commonly used algorithm. The specific algorithm formula is not the subject of this invention, so it will not be described in detail in this specification.

[0086] Through the above control system and control method, the cooling water supply and return water temperature difference control controls the operating frequency of the cooling water pump based on the optimized cooling water supply and return water temperature difference setpoint and the real-time cooling water supply and return water temperature difference of the system. This allows the cooling water pump 3 to operate at the optimized operating frequency, ensuring the safe and stable operation of the system while reducing system energy consumption and achieving energy-saving operation of the central air conditioning cooling water system. This effectively improves the intelligence level of the cooling water system operation.

[0087] Figure 3 To optimize the temperature difference limit range diagram, the optimized temperature difference setpoint is limited to 2℃-7℃, and the cooling water supply temperature is limited to no more than 37.5℃.

[0088] This invention provides a control system and its control method. The control system is equipped with an intelligent controller, which includes two modules and adopts a hierarchical design of control strategies. This fully utilizes the safe and reliable performance of the intelligent controller, enabling not only energy-saving operation of the system but also ensuring the reliability and safety of the system during operation.

[0089] In the embodiments of the present invention, the cooling water supply and return temperature difference is no longer a fixed value, but is calculated by a corresponding algorithm, improving the accuracy and reliability of the cooling water supply and return temperature difference setpoint calculation. The optimized temperature difference setpoint of the cooling water supply and return water can be automatically adjusted according to the real-time changes in the cooling water supply and return water temperatures, improving the automation level of the entire system and reducing the system's response time to environmental changes. Furthermore, the calculation module in the controller 7 calculates the operating frequency of the cooling water pump 3 and sends the operating frequency signal to the frequency converter 6, adjusting the operating frequency of the cooling water pump 3 accordingly. This ensures the safe and stable operation of the system while reducing system energy consumption, achieving energy-saving operation of the central air conditioning cooling water system.

[0090] The central air conditioning cooling water supply and return water temperature difference optimization control method of the present invention can effectively improve the safety and stability of system operation, while saving system operating energy consumption. It solves the problem of high temperature alarm shutdown of chiller unit caused by excessively high cooling water supply temperature when the outdoor temperature is high, and also solves the problem of poor energy saving effect of cooling water system due to equipment failure.

[0091] The present invention also provides a computer-readable storage medium storing computer instructions, which are used to cause a processor to execute the aforementioned method for optimizing the temperature difference between the supply and return cooling water of a central air conditioning system.

[0092] The present invention also provides a central air conditioning cooling water supply and return water temperature difference optimization control device, the central air conditioning cooling water supply and return water temperature difference optimization control device comprising:

[0093] At least one processor and a storage medium, wherein the memory is communicatively connected to the processor;

[0094] The storage medium stores a computer program that can be executed by the at least one processor, and the computer program is executed by the at least one processor to enable the at least one processor to execute the central air conditioning cooling water supply and return water temperature difference optimization control method.

[0095] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A central air conditioning cooling water supply and return water temperature difference optimization control system, characterized in that The system includes a water circuit formed by sequentially connecting a cooling tower (1), a cooling water pump (3) equipped with a frequency converter (6), and a chiller condenser (4), and a controller (7) for controlling the temperature difference between the supply and return water. The cooling tower (1) and the cooling water pump (3) are connected to each other and the cooling water pump (3) and the chiller condenser (4) are connected to each other through a return water pipe (2). The chiller condenser (4) and the cooling tower (1) are connected through a supply water pipe (5). A first temperature sensor (8) and a second temperature sensor (9) are respectively installed on the return water pipe (2) and the supply water pipe (5). The frequency converter (6), the first temperature sensor (8) and the second temperature sensor (9) are electrically connected to the controller (7). The first temperature sensor (8) and the second temperature sensor (9) are used to collect the water supply temperature signal in the return water pipe (2) and the return water temperature signal in the water supply pipe (5), respectively. The controller (7) is used to calculate the optimized temperature difference setpoint based on the supply water temperature signal and the return water temperature signal, and to calculate the real-time cooling water supply and return water temperature difference based on the supply water temperature signal and the return water temperature signal. It determines whether the cooling water supply and return water temperature difference is within the deviation range of the optimized temperature difference setpoint. If it is, it controls the operating frequency of the cooling water pump (3) to remain unchanged from the previous output value. Otherwise, it compares the cooling water supply and return water temperature difference with the optimized temperature difference setpoint, calculates the operating frequency of the frequency converter (6), and outputs it to the frequency converter (6). The upper limit of the optimized temperature difference setpoint is 5℃-7℃; the lower limit of the temperature difference is 2℃-3℃. The inverter (6) controls the speed of the cooling water pump (3) according to the working frequency, and adjusts the temperature difference between the water temperature in the return water pipe (2) and the water temperature in the supply water pipe (5) to the optimized temperature difference setting value. The controller (7) calculates and optimizes the temperature difference setpoint based on the supply water temperature signal and the return water temperature signal as follows: If defined To provide real-time cooling water supply temperature, For real-time cooling water return temperature, To optimize the temperature difference setpoint, This is the default temperature difference setting. The upper limit of the set cooling water supply temperature shall not exceed the high temperature alarm temperature; The formula for calculating the optimized temperature difference setpoint is: if ,but ; if ,and ,but ; if ,and ,but .

2. The central air conditioning cooling water supply and return water temperature difference optimization control system according to claim 1, characterized in that... The above The range is between the upper limit of the temperature difference and the lower limit of the temperature difference. When the optimized temperature difference setting value calculated by the controller (7) is greater than the upper limit of the temperature difference, the optimized temperature difference setting value is determined to be equal to the upper limit of the temperature difference. When the optimized temperature difference setting value calculated by the controller (7) is less than the lower limit of the temperature difference, the optimized temperature difference setting value is determined to be equal to the lower limit of the temperature difference.

3. A method for optimizing the temperature difference between cooling water supply and return water in a central air conditioning system, employing the optimized temperature difference control system for cooling water supply and return water in a central air conditioning system as described in any one of claims 1-2, characterized in that, Includes the following steps: The water supply temperature signal in the return water pipe (2) and the return water temperature signal in the water supply pipe (5) are collected respectively. The optimized temperature difference setpoint is calculated based on the supply water temperature signal and the return water temperature signal. The real-time cooling water supply and return water temperature difference is calculated based on the supply water temperature signal and return water temperature signal. It is determined whether the cooling water supply and return water temperature difference is within the deviation range of the optimized temperature difference setting value. If it is, the operating frequency of the cooling water pump (3) is controlled to remain unchanged from the previous output value. Otherwise, the cooling water supply and return water temperature difference is compared with the optimized temperature difference setting value to determine the operating frequency of the inverter (6). The inverter (6) controls the speed of the cooling water pump (3) according to the operating frequency, and adjusts the temperature difference between the temperature of the water supplied in the return water pipe (2) and the temperature of the water supplied in the supply water pipe (5) to the optimized temperature difference setting value. The step of calculating and optimizing the temperature difference setpoint based on the supply water temperature signal and the return water temperature signal specifically includes the following steps: If defined To provide real-time cooling water supply temperature, For real-time cooling water return temperature, To optimize the temperature difference setpoint, This is the default temperature difference setting. The upper limit of the set cooling water supply temperature shall not exceed the high temperature alarm temperature; The formula for calculating the optimized temperature difference setpoint is: if ,but ; if ,and ,but ; if ,and ,but .

4. The central air conditioning cooling water supply and return water temperature difference optimization control system according to claim 3, characterized in that... The optimized temperature difference setting value is between the upper limit of the temperature difference and the lower limit of the temperature difference. When the optimized temperature difference setting value calculated by the controller (7) is greater than the upper limit of the temperature difference, the optimized temperature difference setting value is determined to be equal to the upper limit of the temperature difference. When the optimized temperature difference setting value calculated by the controller (7) is less than the lower limit of the temperature difference, the optimized temperature difference setting value is determined to be equal to the lower limit of the temperature difference.

5. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions that are used to cause a processor to execute the central air conditioning cooling water supply and return water temperature difference optimization control method as described in any one of claims 3-4.

6. A central air conditioning cooling water supply and return water temperature difference optimization control device, characterized in that, The central air conditioning cooling water supply and return water temperature difference optimization and control equipment includes: At least one processor and a storage medium, the storage medium being communicatively connected to the processor; The storage medium stores a computer program that can be executed by the at least one processor, and the computer program is executed by the at least one processor to enable the at least one processor to perform the central air conditioning cooling water supply and return water temperature difference optimization control method according to any one of claims 3-4.

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