Control method and device of frequency conversion screw machine, air conditioner and storage medium

Abstract

The invention relates to the technical field of air conditioner control, in particular to a control method and device of a frequency conversion screw machine, an air conditioner and a storage medium. The variable-frequency screw machine comprises at least one variable-frequency screw unit, and the control method of the variable-frequency screw machine comprises the steps that firstly, the current cooling water inlet temperature of the variable-frequency screw unit is obtained; then, target chilled water outlet temperature matched with the current cooling water inlet temperature is selected from the first performance data set according to the energy efficiency optimal principle; then, matching a second performance data set according to the target chilled water outlet temperature; and finally, selecting a target unit load, matched with the current cooling water inlet temperature, of the variable-frequency screw unit from the second performance data set according to an energy efficiency optimal principle, so as to control the variable-frequency screw unit to operate based on the target unit load. Therefore, the operation control of the variable-frequency screw machine unit can be optimized and adjusted by taking the performance data as guidance according to the actual working condition, so that the operation efficiency of the variable-frequency screw machine unit is improved.

Description

Technical Field

[0001] This application relates to the field of air conditioning control technology, specifically to a control method, device, air conditioner, and storage medium for a variable frequency screw compressor. Background Technology

[0002] Currently, the control system of variable frequency screw chiller units typically takes the chilled water outlet temperature as the core objective, and stabilizes the chilled water outlet temperature at the target temperature by adjusting the compressor load or frequency.

[0003] To reduce energy consumption, some solutions involve simply adjusting the target temperature (e.g., fixing it upwards by 1°C). In actual operation, this simple adjustment results in limited energy efficiency improvement. Secondly, relying solely on water temperature feedback to adjust compressor load or frequency cannot maintain the unit's optimal operating point under different operating conditions, leading to low energy efficiency. Summary of the Invention

[0004] This application provides a control method, device, air conditioner, and storage medium for a variable frequency screw compressor, which can improve the energy efficiency of the variable frequency screw compressor unit and reduce operating energy consumption.

[0005] In a first aspect, embodiments of this application provide a control method for a variable frequency screw compressor, wherein the variable frequency screw compressor includes at least one variable frequency screw compressor unit, and the control method for the variable frequency screw compressor includes:

[0006] Obtain the current cooling water inlet temperature of the variable frequency screw chiller unit; Based on the principle of optimal energy efficiency, a target chilled water outlet temperature that matches the current cooling water inlet temperature is selected from the first performance dataset; the first performance dataset represents the performance data of the variable frequency screw chiller unit under different cooling water inlet temperatures and different chilled water outlet temperatures; A second performance dataset is matched based on the target chilled water outlet temperature; the second performance dataset characterizes the performance data of the variable frequency screw chiller unit under different cooling water inlet temperatures and different unit loads. Based on the principle of optimal energy efficiency, a target unit load matching the current cooling water inlet temperature of the variable frequency screw turbine is selected from the second performance dataset, so as to control the operation of the variable frequency screw turbine based on the target unit load.

[0007] In some embodiments, selecting a target chilled water outlet temperature that matches the current cooling water inlet temperature from the first performance dataset based on the principle of optimal energy efficiency includes: A first candidate dataset matching the current cooling water inlet temperature is selected from the first performance dataset; the first candidate dataset represents the performance data of the variable frequency screw chiller unit at the current cooling water inlet temperature and different chilled water outlet temperatures. The chilled water outlet temperature with the highest performance data is selected from the first candidate dataset as the target chilled water outlet temperature.

[0008] In some embodiments, selecting a target chilled water outlet temperature that matches the current cooling water inlet temperature from the first performance dataset based on the principle of optimal energy efficiency includes: Obtain the preset range of chilled water temperature; A second candidate dataset is selected from the first performance dataset that matches the current cooling water inlet temperature and the preset range of the chilled water temperature; the second candidate dataset represents the performance data of the variable frequency screw chiller unit at different chilled water outlet temperatures within the current cooling water inlet temperature and the preset range of the chilled water temperature. The chilled water outlet temperature with the highest performance data is selected from the second candidate dataset as the target chilled water outlet temperature.

[0009] In some embodiments, selecting the target unit load of the variable frequency screw turbine unit that matches the current cooling water inlet temperature from the second performance dataset according to the principle of optimal energy efficiency includes: A third candidate dataset matching the current cooling water inlet temperature is selected from the second performance dataset; the third candidate dataset represents the performance data of the variable frequency screw turbine unit under the current cooling water inlet temperature and different unit loads; The unit load with the highest performance data is selected from the third candidate dataset as the target unit load.

[0010] In some embodiments, controlling the operation of the variable frequency screw turbine unit based on the target unit load includes: Obtain the total target load and the number of units; the number of units represents the number of variable frequency screw compressor units in the variable frequency screw compressor. Determine whether the number of units is greater than or equal to the number threshold; When the number of units is greater than or equal to the number threshold, the load of each variable frequency screw turbine unit in the variable frequency screw compressor is allocated based on the total target load and the target unit load to obtain the unit load of each variable frequency screw turbine unit in the variable frequency screw compressor, and the operation of each variable frequency screw turbine unit is controlled accordingly based on the unit load of each variable frequency screw turbine unit.

[0011] In some embodiments, the allocation of the load of each variable frequency screw turbine unit in the variable frequency screw compressor based on the total target load and the target unit load to obtain the unit load of each variable frequency screw turbine unit in the variable frequency screw compressor includes: At least one variable frequency screw compressor unit among the variable frequency screw compressors is selected as the target unit, and the unit load of the target unit is determined as the target unit load; Based on the total target load and the target unit load of the target unit, the unit load of other variable frequency screw turbine units in the variable frequency screw turbine is determined.

[0012] In some embodiments, after determining whether the number of units is greater than or equal to a number threshold, the method further includes: When the number of units is less than the number threshold, the unit load of each variable frequency screw turbine unit in the variable frequency screw turbine is determined based on the total target load.

[0013] Secondly, embodiments of this application provide a control device for a variable frequency screw compressor, the variable frequency screw compressor including at least one variable frequency screw compressor unit, and the control device for the variable frequency screw compressor including: The data acquisition module is used to acquire the current cooling water inlet temperature of the variable frequency screw chiller unit; The water temperature matching module is used to select a target chilled water outlet temperature that matches the current cooling water inlet temperature from the first performance dataset according to the principle of optimal energy efficiency; the first performance dataset represents the performance data of the variable frequency screw chiller unit under different cooling water inlet temperatures and different chilled water outlet temperatures. The data matching module is used to match a second performance dataset based on the target chilled water outlet temperature; the second performance dataset represents the performance data of the variable frequency screw chiller unit under different cooling water inlet temperatures and different unit loads. The load matching module is used to select a target unit load of the variable frequency screw turbine unit that matches the current cooling water inlet temperature from the second performance dataset according to the principle of optimal energy efficiency, so as to control the operation of the variable frequency screw turbine unit based on the target unit load.

[0014] Thirdly, embodiments of this application provide an air conditioner, the air conditioner including: one or more processors, a memory, and one or more application programs, wherein the one or more application programs are stored in the memory and configured to be executed by the processor to implement the control method of the variable frequency screw compressor described in any of the above embodiments.

[0015] Fourthly, embodiments of this application provide a computer-readable storage medium having a computer program stored thereon, the computer program being loaded by a processor to execute the steps in the control method for the variable frequency screw compressor described in any of the above embodiments.

[0016] This application provides a control method, device, air conditioner, and storage medium for a variable frequency screw chiller. By acquiring the current cooling water inlet temperature of the variable frequency screw chiller unit in real time and combining it with a first performance dataset and a second performance dataset, the target chilled water outlet temperature and target unit load of the variable frequency screw chiller unit can be dynamically determined. Therefore, the operation control of the variable frequency screw chiller unit is no longer limited to a fixed water temperature target or empirical correction, but can be optimized and adjusted based on actual operating conditions and guided by performance data, thereby improving the operating efficiency of the variable frequency screw chiller unit. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a flowchart illustrating the control method for a variable frequency screw compressor provided in an embodiment of the present invention.

[0019] Figure 2 This is a flowchart illustrating a method for controlling the operation of a variable frequency screw turbine unit based on the target unit load, according to an embodiment of the present invention.

[0020] Figure 3 This is a flowchart illustrating a method for allocating the load of each variable frequency screw turbine unit when the number of units is greater than or equal to the number threshold provided in an embodiment of the present invention.

[0021] Figure 4 This is a structural block diagram of the control device for a variable frequency screw compressor provided in an embodiment of the present invention.

[0022] Figure 5 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention. Detailed Implementation

[0023] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0024] In the description of this application, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first," "second," "third," etc., may explicitly or implicitly include one or more features.

[0025] In this application, the term "exemplary" is used to mean "used as an example, illustration, or description." Any embodiment described as "exemplary" in this application is not necessarily to be construed as being more preferred or advantageous than other embodiments. The following description is provided to enable any person skilled in the art to make and use this application. Details are set forth in the following description for purposes of explanation. It should be understood that those skilled in the art will recognize that this application can be made without using these specific details. In other instances, well-known structures and processes are not described in detail to avoid obscuring the description of this application with unnecessary detail. Therefore, this application is not intended to be limited to the embodiments shown, but is consistent with the broadest scope of the principles and features disclosed in this application.

[0026] It should be noted that since the method in this application embodiment is executed in a computer device, the processing objects of each computer device exist in the form of data or information, such as time, which is essentially time information. It is understood that if size, quantity, position, etc. are mentioned in subsequent embodiments, they are all corresponding data that exist so that the computer device can process them. Specific details will not be elaborated here.

[0027] This application provides a control method for a variable frequency screw compressor, wherein the variable frequency screw compressor includes at least one variable frequency screw compressor unit. For example... Figure 1 As shown, the control method of the variable frequency screw compressor includes the following steps S1 to S4: Step S1: Obtain the current cooling water inlet temperature of the variable frequency screw chiller unit.

[0028] A variable frequency screw chiller includes at least one variable frequency screw chiller unit. A variable frequency screw chiller unit is a refrigeration device that uses variable frequency technology to drive a screw compressor. Its operating frequency can be adjusted according to actual load demand to achieve energy-saving operation. Variable frequency screw chillers are typically used in large air conditioning systems or industrial refrigeration equipment.

[0029] The cooling water inlet temperature refers to the temperature of the cooling water entering the condenser of the variable frequency screw turbine unit.

[0030] Specifically, the current cooling water inlet temperature of the variable frequency screw chiller unit can be obtained in real time by the temperature sensor inside the pipeline.

[0031] Step S2: Select a target chilled water outlet temperature that matches the current cooling water inlet temperature from the first performance dataset based on the principle of optimal energy efficiency.

[0032] The first performance dataset represents the performance data of the variable frequency screw chiller unit at different cooling water inlet temperatures and different chilled water outlet temperatures.

[0033] Among them, the chilled water outlet temperature refers to the temperature of the chilled water flowing out of the evaporator of the variable frequency screw chiller unit.

[0034] Among them, the performance data characterizes the coefficient of performance (COP) of the variable frequency screw chiller unit. COP is an indicator that measures the energy efficiency ratio of a refrigeration unit, representing the ratio of the cooling capacity (or heating capacity) of the variable frequency screw chiller unit to the input power. The higher the COP value, the higher the energy efficiency of the variable frequency screw chiller unit.

[0035] Among them, the principle of optimal energy efficiency represents matching data in the dataset with the goal of maximizing energy efficiency.

[0036] Specifically, the first performance dataset is a set of performance data of the variable frequency screw chiller unit obtained in advance through experiments or simulations, representing the performance of the unit under different cooling water inlet temperatures and different chilled water outlet temperatures. The first performance dataset can be in the form of tables or sets of curves, etc.

[0037] Specifically, when the variable frequency screw compressor leaves the factory, an electromagnetic flow meter (accuracy ±0.5%) and an electricity meter (accuracy ±0.2%) can be installed in the water circuit of the compressor unit to collect data on flow rate, power consumption, temperature, etc., under more than 100 sets of operating conditions, generating an initial first performance dataset. Furthermore, during the operation of the variable frequency screw compressor, the operating data can be automatically analyzed every 24 hours. If the measured performance data (COP) under a certain operating condition deviates from the performance data in the first performance dataset by more than 5% (e.g., when cooling water is 32℃ and chilled water is 8℃, the measured performance data is 5.3, but the performance data in the first performance dataset is 5.6), the data in the first performance dataset will be automatically corrected to ensure that the performance data always stays close to the optimal value during long-term operation.

[0038] For example, the first performance dataset can be in tabular form. See Table 1 below for details: Table 1 First Performance Dataset

[0039] As shown in Table 1 above, the first row of cells in Table 1 represents the cooling water inlet temperature in °C; the first column of cells represents the chilled water outlet temperature in °C; and the remaining cells in Table 1 contain performance data. For example, when the cooling water inlet temperature is 25 °C, if the chilled water outlet temperature is set to 5 °C, the performance data is 5.8; if the chilled water outlet temperature is set to 12 °C, the performance data is 7.1. This means that with a cooling water inlet temperature of 25 °C, the performance data is higher and the energy efficiency is higher when the chilled water outlet temperature is 12 °C.

[0040] The target chilled water outlet temperature refers to the chilled water outlet temperature that, through calculation or query, enables the variable frequency screw chiller unit to achieve the highest performance data (e.g., COP) under the current cooling water inlet temperature.

[0041] Specifically, based on the current cooling water inlet temperature, a set of chilled water outlet temperatures and their corresponding performance data that are close to or match the current cooling water inlet temperature can be found in the first performance dataset. Then, a chilled water outlet temperature can be selected from this set of data as the target chilled water outlet temperature. This selection can be based on a preset optimization strategy, such as selecting a temperature value that allows the unit to operate in a relatively stable range, or selecting a recommended temperature value that has been verified under specific operating conditions.

[0042] In some embodiments, step S2 above, selecting a target chilled water outlet temperature that matches the current cooling water inlet temperature from the first performance dataset according to the principle of optimal energy efficiency, may include: selecting a first candidate dataset that matches the current cooling water inlet temperature from the first performance dataset; and selecting the chilled water outlet temperature with the highest performance data from the first candidate dataset as the target chilled water outlet temperature.

[0043] The first candidate dataset represents the performance data of the variable frequency screw chiller unit at the current cooling water inlet temperature and different chilled water outlet temperatures.

[0044] Specifically, after obtaining the current cooling water inlet temperature of the variable frequency screw chiller unit, a first candidate dataset corresponding to the current cooling water inlet temperature is matched from the first performance dataset. The first candidate dataset includes performance data of the variable frequency screw chiller unit under different chilled water outlet temperatures at the current cooling water inlet temperature. For example, the first performance dataset can be a multidimensional lookup table or database containing the cooling water inlet temperature, chilled water outlet temperature, and corresponding performance data. Selecting the first candidate dataset matching the current cooling water inlet temperature from the first performance dataset means extracting a subset of performance data corresponding to different chilled water outlet temperatures at a fixed cooling water inlet temperature from the multidimensional data. This process can be achieved through database queries, data filtering, or index lookups.

[0045] Subsequently, the first candidate dataset is analyzed, and the chilled water outlet temperature with the highest performance data is selected as the target chilled water outlet temperature. By comparing the performance values ​​corresponding to each chilled water outlet temperature in the first candidate dataset, the chilled water outlet temperature at which the variable frequency screw chiller unit achieves the highest operating efficiency under the current cooling water inlet temperature can be accurately located. This process can be achieved by traversing the first candidate dataset to find the extreme points of the performance data. Once this extreme point is found, its corresponding chilled water outlet temperature is determined as the target chilled water outlet temperature.

[0046] For example, as shown in Table 1 above, when the current cooling water inlet temperature is 30℃, the extractable data are: chilled water outlet temperature of 5℃ and corresponding performance data of 5.1; chilled water outlet temperature of 7℃ and corresponding performance data of 5.5; chilled water outlet temperature of 8℃ and corresponding performance data of 5.7; chilled water outlet temperature of 9℃ and corresponding performance data of 5.9; and chilled water outlet temperature of 12℃ and corresponding performance data of 6.4. In this case, the first candidate dataset can include these extracted data. Simultaneously, the chilled water outlet temperature with the highest performance data (6.4) is selected from the first candidate dataset, which is currently the highest performance data in the first candidate dataset, and the corresponding chilled water outlet temperature is 12℃. Therefore, the target chilled water outlet temperature is 12℃.

[0047] In this embodiment, the determination of the target chilled water outlet temperature is no longer simply based on data, but rather incorporates a performance optimization strategy under current operating conditions. First, a first set of candidate data is selected based on the current cooling water inlet temperature. Then, the chilled water outlet temperature with the best energy efficiency is found from this first set of candidate data, ensuring that the determined target chilled water outlet temperature represents the point where the variable frequency screw chiller unit operates with the highest efficiency under current conditions. This approach reduces energy waste caused by selecting a non-optimal chilled water outlet temperature, thereby improving the overall operating efficiency and energy-saving effect of the variable frequency screw chiller unit.

[0048] In some embodiments, step S2 above, selecting a target chilled water outlet temperature that matches the current cooling water inlet temperature from the first performance dataset according to the principle of optimal energy efficiency, may include: obtaining a preset range of chilled water temperature; selecting a second candidate dataset that matches the current cooling water inlet temperature and the preset range of chilled water temperature from the first performance dataset; and selecting the chilled water outlet temperature with the highest performance data from the second candidate dataset as the target chilled water outlet temperature.

[0049] The second candidate dataset represents the performance data of the variable frequency screw chiller unit at different chilled water outlet temperatures within the current preset range of cooling water inlet temperature and chilled water temperature.

[0050] The chilled water temperature preset range is a temperature interval used to set a boundary for selecting the chilled water outlet temperature. In other words, the chilled water outlet temperature must be within this preset range. The chilled water temperature preset range can be a fixed temperature interval, such as a parameter preset and stored in the control system by the system designer or user based on actual cooling demand, equipment safety operation requirements, and energy-saving goals. Alternatively, the chilled water temperature preset range can be a dynamically adjusted temperature interval, for example, determined in real-time based on factors such as external ambient temperature, building load changes, or user preferences.

[0051] Specifically, after obtaining the current cooling water inlet temperature and the preset range of chilled water temperature for the variable frequency screw chiller unit, a second candidate dataset corresponding to the current cooling water inlet temperature and the preset range of chilled water temperature is selected from the first performance dataset. The second candidate dataset includes performance data of the variable frequency screw chiller unit under different chilled water outlet temperatures within the current preset range of cooling water inlet temperature and chilled water temperature. For example, the first performance dataset can be a multidimensional lookup table or database containing the cooling water inlet temperature, chilled water outlet temperature, and corresponding performance data. Selecting the second candidate dataset matching the current preset range of cooling water inlet temperature and chilled water temperature from the first performance dataset can be achieved by extracting a subset of performance data corresponding to different chilled water outlet temperatures within the preset range of chilled water temperature at a fixed cooling water inlet temperature from the multidimensional data. This process can be implemented through database queries, data filtering, or index lookups. This process narrows the search space for the target chilled water outlet temperature and eliminates temperature options that do not meet actual operating constraints.

[0052] Subsequently, the chilled water outlet temperature with the highest performance data is selected from the second candidate dataset. This can be done by comparing all performance data in the second candidate dataset and selecting the chilled water outlet temperature at the point where the performance data is highest. The chilled water outlet temperature corresponding to this highest performance data point is then determined as the target chilled water outlet temperature.

[0053] For example, as shown in Table 1 above, when the current cooling water inlet temperature is 30℃ and the preset range of chilled water temperature is 5℃ to 10℃, the extractable data are: chilled water outlet temperature of 5℃ and corresponding performance data of 5.1; chilled water outlet temperature of 7℃ and corresponding performance data of 5.5; chilled water outlet temperature of 8℃ and corresponding performance data of 5.7; chilled water outlet temperature of 9℃ and corresponding performance data of 5.9. In this case, the second candidate dataset can include these extracted data. Simultaneously, the chilled water outlet temperature with the highest performance data (i.e., performance data of 5.9) is selected from the second candidate dataset, which is currently the highest performance data in the second candidate dataset, and the corresponding chilled water outlet temperature is 9℃. Therefore, the target chilled water outlet temperature is 9℃.

[0054] In this embodiment, a preset range for chilled water temperature is first obtained, which defines a reasonable operating range for the chilled water outlet temperature. Then, based on this preset range, a second candidate dataset that meets the criteria is selected from the first performance dataset, ensuring that all candidate chilled water outlet temperatures fall within the set range. Finally, the chilled water outlet temperature with the highest performance data is selected from these selected second candidate datasets as the target chilled water outlet temperature. This method ensures that the determined target chilled water outlet temperature not only guarantees the high-efficiency operation of the variable frequency screw chiller unit under current operating conditions, but also ensures the stable, safe, and efficient operation of the entire chilled water system and terminal equipment, reducing systemic problems caused by solely pursuing unit efficiency, thereby improving the unit's operational reliability and overall energy efficiency.

[0055] Step S3: Match the second performance dataset according to the target chilled water outlet temperature.

[0056] The second performance dataset characterizes the performance data of the variable frequency screw chiller unit at the target chilled water outlet temperature, under different cooling water inlet temperatures and different unit loads.

[0057] The unit load of a variable frequency screw chiller unit represents the ratio of its actual output cooling capacity to its rated cooling capacity, or the ratio of its actual output heating capacity to its rated heating capacity. The unit load is a core indicator used to measure the load on the variable frequency screw chiller unit under its current operating conditions, and is usually expressed as a percentage (%).

[0058] For example, the second performance dataset can be in tabular form. If the chilled water outlet temperature is 7°C, see Table 2 below for details: Table 2 Second Performance Dataset

[0059] As shown in Table 2 above, the first cell in Table 2 is the cooling water inlet temperature, in °C; the first cell in Table 2 is the unit load of the variable frequency screw chiller, expressed as a percentage (%); the remaining cells in Table 2 are performance data.

[0060] In some embodiments, step S3 above, matching the second performance dataset according to the target chilled water outlet temperature, includes: obtaining a third performance dataset; and selecting a second performance dataset from the third performance dataset that matches the target chilled water outlet temperature.

[0061] The third performance dataset represents the performance data of the variable frequency screw chiller unit under different cooling water inlet temperatures and different unit loads at multiple fixed chilled water outlet temperatures.

[0062] Specifically, the third performance dataset is a set of performance data obtained in advance through experiments or simulations, characterizing the performance of the variable frequency screw chiller unit under multiple fixed chilled water outlet temperatures, different cooling water inlet temperatures, and different unit loads. The third performance dataset can be in the form of tables or sets of curves, etc.

[0063] Specifically, when the variable frequency screw compressor leaves the factory, electromagnetic flow meters (accuracy ±0.5%) and electricity meters (accuracy ±0.2%) can be installed in the water circuit of the compressor unit to collect data on flow rate, power consumption, temperature, etc., under more than 100 different operating conditions, generating an initial third performance dataset. Furthermore, during the operation of the variable frequency screw compressor, the operating data can be automatically analyzed every 24 hours. If the measured performance data (COP) under a certain operating condition deviates from the performance data in the third performance dataset by more than 5%, the data in the third performance dataset will be automatically corrected to ensure that the performance data remains close to the optimal value throughout long-term operation.

[0064] Step S4: Select the target unit load of the variable frequency screw turbine unit that matches the current cooling water inlet temperature from the second performance dataset according to the principle of optimal energy efficiency, so as to control the operation of the variable frequency screw turbine unit based on the target unit load.

[0065] The target unit load represents the unit load that enables the variable frequency screw turbine to achieve its highest performance data at the target chilled water outlet temperature and the current cooling water inlet temperature.

[0066] Specifically, the second performance dataset includes performance data of the variable frequency screw chiller unit at the target chilled water outlet temperature, under different cooling water inlet temperatures and different unit loads. Therefore, the unit loads in the second performance dataset are all under the condition of the target chilled water outlet temperature.

[0067] Specifically, based on the principle of optimal energy efficiency, the target unit load of the variable frequency screw turbine unit, matching the current cooling water inlet temperature, is selected from the second performance dataset. A set of unit loads and their corresponding performance data with a temperature close to or matching the current cooling water inlet temperature can be found in the second performance dataset. Then, a unit load can be selected from this set of data as the target unit load. This selection can be based on a preset operating strategy, such as selecting a load value that matches the unit's output power with the current load demand, or selecting a recommended load value that ensures stable system operation.

[0068] Finally, based on the determined target unit load, the variable frequency screw chiller is operated under control. For example, the target unit load can be sent to the variable frequency screw chiller's controller, which then adjusts the compressor's operating frequency or loading / unloading status to bring the actual operating load of the unit closer to the target unit load. Thus, the operating state of the variable frequency screw chiller is adjusted to adapt to the current operating conditions.

[0069] In this embodiment, by acquiring the current cooling water inlet temperature of the variable frequency screw chiller unit in real time, and combining it with the first performance dataset and the second performance dataset, the target chilled water outlet temperature and target unit load of the variable frequency screw chiller unit can be dynamically determined. Therefore, the unit's operation control is no longer limited to fixed water temperature targets or empirical corrections, but can be optimized and adjusted based on actual operating conditions and guided by performance data, thereby improving the operating efficiency of the variable frequency screw chiller unit.

[0070] In some embodiments, step S4 above, selecting the target unit load of the variable frequency screw turbine unit that matches the current cooling water inlet temperature from the second performance dataset according to the principle of optimal energy efficiency, includes: selecting a third candidate dataset that matches the current cooling water inlet temperature from the second performance dataset; and selecting the unit load with the highest performance data from the third candidate dataset as the target unit load.

[0071] The third candidate dataset represents the performance data of the variable frequency screw chiller unit under the target chilled water outlet temperature, the current cooling water inlet temperature, and different unit loads.

[0072] Specifically, the third candidate dataset includes performance data of the variable frequency screw chiller unit under the target chilled water outlet temperature, the current cooling water inlet temperature, and different unit loads. For example, the second performance dataset can be a multidimensional lookup table or database containing a set of performance data under different cooling water inlet temperatures and different unit loads. Selecting the third candidate dataset from the second performance dataset that matches the current cooling water inlet temperature means extracting the performance data corresponding to different unit loads at the current cooling water inlet temperature from the second performance dataset. This process can be achieved through database queries, data filtering, or index lookups.

[0073] Subsequently, the third candidate dataset is analyzed, and the unit load with the highest performance data is selected from it; this unit load is the target unit load. By comparing the performance values ​​corresponding to each unit load in the third candidate dataset, the unit load with the highest operating efficiency of the variable frequency screw turbine unit under the current cooling water inlet temperature can be accurately located. This process can be achieved by traversing the third candidate dataset to find the extreme points of the performance data. Once this extreme point is found, the corresponding unit load is determined as the target unit load.

[0074] Finally, based on the determined target unit load, the variable frequency screw chiller is operated under control. For example, the target unit load can be sent to the variable frequency screw chiller's controller, which then adjusts the compressor's operating frequency or loading / unloading status to bring the actual operating load of the unit closer to the target unit load. Thus, the operating state of the variable frequency screw chiller is adjusted to adapt to the current operating conditions.

[0075] For example, as shown in Table 2 above, when the target chilled water outlet temperature is 7℃ and the current cooling water inlet temperature is 32℃, the extractable data are: unit load at 100%, with a corresponding performance value of 5.880; unit load at 90%, with a corresponding performance value of 5.870; unit load at 80%, with a corresponding performance value of 5.821; unit load at 70%, with a corresponding performance value of 5.738; unit load at 60%, with a corresponding performance value of 5.829; unit load at 50%, with a corresponding performance value of 5.898; unit load at 40%, with a corresponding performance value of 5.792; and unit load at 30%, with a corresponding performance value of 5.269. The third candidate dataset can then include these extracted data. Simultaneously, the unit load with the highest performance value (5.898) is selected from the third candidate dataset, corresponding to a unit load of 50%. Therefore, the target unit load is 50%.

[0076] In this embodiment, a third candidate dataset corresponding to the current cooling water outlet temperature is first selected from the second performance dataset. This third candidate dataset contains performance data of the variable frequency screw chiller unit under different unit loads at this specific temperature combination (target chilled water outlet temperature and current cooling water outlet temperature). Subsequently, the unit load with the highest performance data is selected as the target unit load from the third candidate dataset. This method ensures that the variable frequency screw chiller unit always operates at the optimal load point under given chilled water outlet temperature and cooling water outlet temperature conditions, thereby improving the unit's operating efficiency and reducing energy consumption.

[0077] In some embodiments, such as Figure 2 As shown, the method for controlling the operation of the variable frequency screw turbine unit based on the target unit load in step S4 above includes steps S41, S42, and S43: Step S41: Obtain the total target load and the number of units. The number of units represents the number of variable frequency screw compressor units in the variable frequency screw compressor.

[0078] The total load target refers to the total cooling capacity, total heating capacity, or total output power that the entire variable frequency screw chiller needs to provide. This total load target can be set by the upper-level control system according to actual needs, for example, through input via a user interface or by receiving instructions from the building management system. Furthermore, the total target load can also be obtained by real-time monitoring and calculation of chilled water supply and return temperatures and flow rates, combined with load forecasting algorithms, to predict future load demand.

[0079] The number of variable frequency screw compressor units refers to the total number of variable frequency screw compressor units currently in operation or available for use. This number can be preset through system configuration parameters or dynamically counted by monitoring the online status and operating mode of each unit through real-time communication.

[0080] Step S42: Determine whether the number of units is greater than or equal to the number threshold.

[0081] The quantity threshold is used to define special handling strategies when the number of variable frequency screw turbine units reaches a certain scale. For example, when the number of variable frequency screw turbine units is large (greater than or equal to the quantity threshold), a more refined load allocation strategy can be adopted to optimize overall operating efficiency. This quantity threshold can be flexibly set according to factors such as the actual application scenario, system scale, unit type, and desired control accuracy. For example, the quantity threshold can be set to 2 or other values.

[0082] Step S43: When the number of units is greater than or equal to the number threshold, the load of each variable frequency screw turbine unit in the variable frequency screw compressor is allocated based on the total target load and the target unit load to obtain the unit load of each variable frequency screw turbine unit in the variable frequency screw compressor, and the operation of each variable frequency screw turbine unit is controlled accordingly based on the unit load of each variable frequency screw turbine unit.

[0083] The target unit load is determined based on the performance data of a single variable frequency screw turbine unit under specific operating conditions (which include the current cooling water inlet temperature and the target chilled water outlet temperature). It typically corresponds to the unit's highest energy efficiency ratio.

[0084] The unit load of each variable frequency screw turbine unit is the final operating load of each variable frequency screw turbine unit after load allocation. Various load allocation strategies can be adopted based on the relationship between the total target load and the target unit load of each unit. For example, when the total target load is low (e.g., below 70% of the rated load of a single variable frequency screw turbine unit), only one variable frequency screw turbine unit can be started and operated in its high-efficiency range close to the target unit load. When the total target load is high (e.g., above 70% of the rated load of a single variable frequency screw turbine unit), more units can be started, and load scheduling can be performed based on the rated capacity, current operating efficiency, and target unit load of each unit, through weighted allocation, proportional allocation, or optimization algorithms (such as dynamic programming or linear programming) to optimize overall energy efficiency.

[0085] In some embodiments, such as Figure 3 As shown, step S43 above, which involves allocating the load of each variable frequency screw turbine unit in the variable frequency screw compressor based on the total target load and the target unit load to obtain the unit load of each variable frequency screw turbine unit in the variable frequency screw compressor, includes the following steps S431 and S432: Step S431: Select at least one variable frequency screw compressor unit as the target unit, and determine the unit load of the target unit as the target unit load.

[0086] Step S432: Based on the total target load and the target unit load of the target unit, determine the unit load of other variable frequency screw turbine units in the variable frequency screw turbine.

[0087] Specifically, when determining the target unit, dynamic evaluation and selection can be performed based on factors such as the historical operating data and current operating status (e.g., operating time, maintenance cycle) of each variable frequency screw compressor unit. Typically, the unit with the highest current energy efficiency data or the most suitable unit to undertake the baseline load is selected as the target unit. Once the target unit is determined, its load will be set as the aforementioned target unit load.

[0088] Subsequently, based on this, the load of other variable frequency screw turbine units in the variable frequency screw compressor system will be determined according to the total target load and the target unit load of the target unit. Specifically, after determining the load of the target unit, the remaining total target load minus the target unit load of all target units is the load that needs to be borne by the other variable frequency screw turbine units. The method for determining the load of these other variable frequency screw turbine units can be varied. For example, the remaining load can be evenly distributed among the remaining units; or a weighted distribution can be performed based on the capacity, current operating status, or their respective energy efficiency curves of each remaining unit to further optimize overall energy efficiency. This hierarchical load allocation strategy allows for more flexible and efficient utilization of the performance characteristics of each unit while meeting the total load demand.

[0089] In this embodiment, when the number of variable frequency screw turbine units reaches a certain scale (greater than or equal to a number threshold), at least one variable frequency screw turbine unit is selected as the target unit and operated at the optimal energy efficiency point indicated by the target unit's load. This strategy solves the problem of overall energy efficiency degradation that may result from simply distributing the load evenly in multi-unit scenarios. By prioritizing ensuring that one or more units operate at maximum efficiency, and then rationally allocating the remaining total target load to other units, the entire variable frequency screw turbine system can achieve better energy efficiency performance. This load allocation mechanism not only improves the system's operating efficiency and reduces energy consumption, but also helps extend the unit's service life and enhances the system's operational stability because it reduces the possibility of all units deviating from their optimal operating points.

[0090] In some embodiments, after step S42, determining whether the number of units is greater than or equal to the number threshold, the method further includes: step S44, when the number of units is less than the number threshold, determining the unit load of each variable frequency screw turbine unit in the variable frequency screw turbine based on the total target load.

[0091] Specifically, when the number of units is less than a threshold (e.g., the threshold could be 2), it means that the number of actually operating variable frequency screw turbine units in the variable frequency screw compressor system is lower than the preset minimum number of units required to execute a specific load allocation strategy. This situation may occur when some units are in standby mode or when some units fail and are taken out of operation. In this case, instead of prioritizing allocation to the target units, the load of each variable frequency screw turbine unit is determined based on the total target load that the entire variable frequency screw compressor system needs to bear. This determination process can be implemented in several ways. For example, the total target load can be evenly distributed to all currently operating variable frequency screw turbine units; or, based on factors such as the rated capacity, historical operating efficiency, or current operating status of each variable frequency screw turbine unit, different weights or proportions can be set to distribute the total target load proportionally to each unit; or, if the number of units is 1, then this single operating variable frequency screw turbine unit will bear the entire total target load. Thus, while meeting the total target load, a more energy-efficient load allocation scheme is sought to improve the overall energy efficiency of the system.

[0092] This embodiment provides a control method for a variable frequency screw compressor. By acquiring the current cooling water inlet temperature of the variable frequency screw compressor unit in real time and combining it with a first performance dataset and a second performance dataset, the target chilled water outlet temperature and target unit load of the variable frequency screw compressor unit can be dynamically determined. Therefore, the operation control of the variable frequency screw compressor unit is no longer limited to fixed water temperature targets or empirical corrections, but can be optimized and adjusted based on actual operating conditions and guided by performance data, thereby improving the operating efficiency of the variable frequency screw compressor unit.

[0093] This application embodiment also provides a control device 400 for a variable frequency screw compressor, such as... Figure 4 As shown, the variable frequency screw compressor includes at least one variable frequency screw compressor unit, and the control device 400 of the variable frequency screw compressor includes: Data acquisition module 401 is used to acquire the current cooling water inlet temperature of the variable frequency screw chiller unit; The water temperature matching module 402 is used to select a target chilled water outlet temperature that matches the current cooling water inlet temperature from the first performance dataset according to the principle of optimal energy efficiency; the first performance dataset represents the performance data of the variable frequency screw chiller unit under different cooling water inlet temperatures and different chilled water outlet temperatures. Data matching module 403 is used to match a second performance dataset based on the target chilled water outlet temperature; the second performance dataset represents the performance data of the variable frequency screw chiller unit under different cooling water inlet temperatures and different unit loads; The load matching module 404 is used to select the target unit load of the variable frequency screw turbine unit that matches the current cooling water inlet temperature from the second performance dataset according to the principle of optimal energy efficiency, so as to control the operation of the variable frequency screw turbine unit based on the target unit load.

[0094] It should be noted that the structure and function of the control device 400 for the variable frequency screw compressor correspond to the control method for the variable frequency screw compressor described above. For any parts of the control device 400 not described in detail, please refer to the control method for the variable frequency screw compressor in the above embodiment; further details will not be provided here.

[0095] This application also provides an air conditioner, which includes one or more processors, a memory, and one or more application programs, wherein the one or more application programs are stored in the memory and configured to be executed by the processor to implement the variable frequency screw compressor control method in any of the above embodiments.

[0096] This application also provides an electronic device that integrates the control device for any of the variable frequency screw compressors provided in this application. For example... Figure 5 As shown, it illustrates a structural schematic diagram of the electronic device involved in the embodiments of this application, specifically: The electronic device may include components such as a processor 801 with one or more processing cores, a memory 802 with one or more computer-readable storage media, a power supply 803, and an input unit 804. Those skilled in the art will understand that... Figure 5 The electronic device structure shown does not constitute a limitation on the electronic device and may include more or fewer components than shown, or combine certain components, or have different component arrangements. Wherein: The processor 801 is the control center of the electronic device. It connects various parts of the electronic device via various interfaces and lines. By running or executing software programs and / or modules stored in the memory 802, and by calling data stored in the memory 802, it performs various functions and processes data, thereby providing overall monitoring of the electronic device. Optionally, the processor 801 may include one or more processing cores; preferably, the processor 801 may integrate an application processor and a modem processor, wherein the application processor mainly handles the operating system, user interface, and applications, and the modem processor mainly handles wireless communication. It is understood that the modem processor may not be integrated into the processor 801.

[0097] The memory 802 can be used to store software programs and modules. The processor 801 executes various functional applications and data processing by running the software programs and modules stored in the memory 802. The memory 802 may mainly include a program storage area and a data storage area. The program storage area may store the operating system, application programs required for at least one function (such as sound playback function, image playback function, etc.), etc.; the data storage area may store data created according to the use of the electronic device, etc. In addition, the memory 802 may include high-speed random access memory, and may also include non-volatile memory, such as at least one disk storage device, flash memory device, or other volatile solid-state storage device. Accordingly, the memory 802 may also include a memory controller to provide the processor 801 with access to the memory 802.

[0098] The electronic device also includes a power supply 803 that supplies power to the various components. Preferably, the power supply 803 can be logically connected to the processor 801 through a power management system, thereby enabling functions such as charging, discharging, and power consumption management through the power management system. The power supply 803 may also include one or more DC or AC power supplies, recharging systems, power fault detection circuits, power converters or inverters, power status indicators, and other arbitrary components.

[0099] The electronic device may also include an input unit 804, which can be used to receive input digital or character information and generate keyboard, mouse, joystick, optical or trackball signal inputs related to user settings and function control.

[0100] Although not shown, the electronic device may also include a display unit, etc., which will not be described in detail here. Specifically, in this embodiment, the processor 801 in the electronic device loads the executable files corresponding to the processes of one or more application programs into the memory 802 according to the following instructions, and the processor 801 runs the application programs stored in the memory 802 to realize various functions, such as: Obtain the current cooling water inlet temperature of the variable frequency screw chiller unit; Based on the principle of optimal energy efficiency, a target chilled water outlet temperature that matches the current cooling water inlet temperature is selected from the first performance dataset; the first performance dataset represents the performance data of the variable frequency screw chiller unit under different cooling water inlet temperatures and different chilled water outlet temperatures; A second performance dataset is matched based on the target chilled water outlet temperature; the second performance dataset characterizes the performance data of the variable frequency screw chiller unit under different cooling water inlet temperatures and different unit loads. Based on the principle of optimal energy efficiency, the target unit load of the variable frequency screw turbine unit that matches the current cooling water inlet temperature is selected from the second performance dataset, so as to control the operation of the variable frequency screw turbine unit based on the target unit load.

[0101] Those skilled in the art will understand that all or part of the steps in the various methods of the above embodiments can be performed by instructions, or by instructions controlling related hardware. These instructions can be stored in a computer-readable storage medium and loaded and executed by a processor.

[0102] Therefore, embodiments of this application provide a computer-readable storage medium, which may include: read-only memory (ROM), random access memory (RAM), a magnetic disk, or an optical disk, etc. A computer program is stored thereon, and the computer program is loaded by a processor to execute the steps in any of the variable frequency screw compressor control methods provided in embodiments of this application. For example, the computer program loaded by the processor can execute the following steps: Obtain the current cooling water inlet temperature of the variable frequency screw chiller unit; Based on the principle of optimal energy efficiency, a target chilled water outlet temperature that matches the current cooling water inlet temperature is selected from the first performance dataset; the first performance dataset represents the performance data of the variable frequency screw chiller unit under different cooling water inlet temperatures and different chilled water outlet temperatures; A second performance dataset is matched based on the target chilled water outlet temperature; the second performance dataset characterizes the performance data of the variable frequency screw chiller unit under different cooling water inlet temperatures and different unit loads. Based on the principle of optimal energy efficiency, the target unit load of the variable frequency screw turbine unit that matches the current cooling water inlet temperature is selected from the second performance dataset, so as to control the operation of the variable frequency screw turbine unit based on the target unit load.

[0103] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the detailed descriptions of other embodiments above, which will not be repeated here.

[0104] In practice, each of the above units or structures can be implemented as an independent entity or can be arbitrarily combined to be implemented as the same or several entities. For the specific implementation of each of the above units or structures, please refer to the previous method embodiments, which will not be repeated here.

[0105] For details on the implementation of each of the above operations, please refer to the previous examples, which will not be repeated here.

[0106] The control method, device, air conditioner, and storage medium of a variable frequency screw compressor provided in the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A control method for a variable frequency screw compressor, characterized in that, The variable frequency screw compressor includes at least one variable frequency screw compressor unit, and the control method of the variable frequency screw compressor includes: Obtain the current cooling water inlet temperature of the variable frequency screw chiller unit; Based on the principle of optimal energy efficiency, a target chilled water outlet temperature that matches the current cooling water inlet temperature is selected from the first performance dataset; the first performance dataset represents the performance data of the variable frequency screw chiller unit under different cooling water inlet temperatures and different chilled water outlet temperatures; A second performance dataset is matched based on the target chilled water outlet temperature; the second performance dataset characterizes the performance data of the variable frequency screw chiller unit under different cooling water inlet temperatures and different unit loads. Based on the principle of optimal energy efficiency, a target unit load matching the current cooling water inlet temperature of the variable frequency screw turbine is selected from the second performance dataset, so as to control the operation of the variable frequency screw turbine based on the target unit load.

2. The control method for a variable frequency screw compressor according to claim 1, characterized in that, The step of selecting a target chilled water outlet temperature that matches the current cooling water inlet temperature from the first performance dataset based on the principle of optimal energy efficiency includes: A first candidate dataset matching the current cooling water inlet temperature is selected from the first performance dataset; the first candidate dataset represents the performance data of the variable frequency screw chiller unit at the current cooling water inlet temperature and different chilled water outlet temperatures. The chilled water outlet temperature with the highest performance data is selected from the first candidate dataset as the target chilled water outlet temperature.

3. The control method for a variable frequency screw compressor according to claim 1, characterized in that, The step of selecting a target chilled water outlet temperature that matches the current cooling water inlet temperature from the first performance dataset based on the principle of optimal energy efficiency includes: Obtain the preset range of chilled water temperature; A second candidate dataset is selected from the first performance dataset that matches the current cooling water inlet temperature and the preset range of the chilled water temperature; the second candidate dataset represents the performance data of the variable frequency screw chiller unit at different chilled water outlet temperatures within the current cooling water inlet temperature and the preset range of the chilled water temperature. The chilled water outlet temperature with the highest performance data is selected from the second candidate dataset as the target chilled water outlet temperature.

4. The control method for a variable frequency screw compressor according to claim 1, characterized in that, The step of selecting the target unit load of the variable frequency screw turbine unit that matches the current cooling water inlet temperature from the second performance dataset according to the principle of optimal energy efficiency includes: A third candidate dataset matching the current cooling water inlet temperature is selected from the second performance dataset; the third candidate dataset represents the performance data of the variable frequency screw turbine unit under the current cooling water inlet temperature and different unit loads; The unit load with the highest performance data is selected from the third candidate dataset as the target unit load.

5. The control method for a variable frequency screw compressor according to claim 1, characterized in that, The method of controlling the operation of the variable frequency screw turbine unit based on the target unit load includes: Obtain the total target load and the number of units; the number of units represents the number of variable frequency screw compressor units in the variable frequency screw compressor. Determine whether the number of units is greater than or equal to the number threshold; When the number of units is greater than or equal to the number threshold, the load of each variable frequency screw turbine unit in the variable frequency screw compressor is allocated based on the total target load and the target unit load to obtain the unit load of each variable frequency screw turbine unit in the variable frequency screw compressor, and the operation of each variable frequency screw turbine unit is controlled accordingly based on the unit load of each variable frequency screw turbine unit.

6. The control method for a variable frequency screw compressor according to claim 5, characterized in that, The process of allocating the load of each variable frequency screw turbine unit in the variable frequency screw compressor based on the total target load and the target unit load to obtain the unit load of each variable frequency screw turbine unit in the variable frequency screw compressor includes: At least one variable frequency screw compressor unit among the variable frequency screw compressors is selected as the target unit, and the unit load of the target unit is determined as the target unit load; Based on the total target load and the target unit load of the target unit, the unit load of other variable frequency screw turbine units in the variable frequency screw turbine is determined.

7. The control method for a variable frequency screw compressor according to claim 5, characterized in that, After determining whether the number of units is greater than or equal to the number threshold, the method further includes: When the number of units is less than the number threshold, the unit load of each variable frequency screw turbine unit in the variable frequency screw turbine is determined based on the total target load.

8. A control device for a variable frequency screw compressor, characterized in that, The variable frequency screw compressor includes at least one variable frequency screw compressor unit, and the control device of the variable frequency screw compressor includes: The data acquisition module is used to acquire the current cooling water inlet temperature of the variable frequency screw chiller unit; The water temperature matching module is used to select a target chilled water outlet temperature that matches the current cooling water inlet temperature from the first performance dataset according to the principle of optimal energy efficiency; the first performance dataset represents the performance data of the variable frequency screw chiller unit under different cooling water inlet temperatures and different chilled water outlet temperatures. The data matching module is used to match a second performance dataset based on the target chilled water outlet temperature; the second performance dataset represents the performance data of the variable frequency screw chiller unit under different cooling water inlet temperatures and different unit loads. The load matching module is used to select a target unit load of the variable frequency screw turbine unit that matches the current cooling water inlet temperature from the second performance dataset according to the principle of optimal energy efficiency, so as to control the operation of the variable frequency screw turbine unit based on the target unit load.

9. An air conditioner, characterized in that, The air conditioner includes: one or more processors, a memory, and one or more application programs, wherein the one or more application programs are stored in the memory and configured to be executed by the processor to implement the control method of the variable frequency screw compressor according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, It stores a computer program, which is loaded by a processor to execute the steps in the control method of the variable frequency screw compressor according to any one of claims 1 to 7.

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