Water chilling unit air conditioning system and control method thereof

Abstract

The invention provides a water chilling unit air conditioning system and a control method thereof. The water chilling unit air conditioning system comprises a plurality of water chilling units and a controller. The controller is configured to establish a performance model of the water chilling unit; target parameters of each water chilling unit in the multiple water chilling units under the multiple working conditions are calculated; the multiple working conditions are different from one another, and the opening numbers of the multiple water chilling units are different under the multiple working conditions; calculating a predicted energy efficiency ratio of each water chilling unit according to the performance model of the water chilling unit and at least one of the target parameters of each water chilling unit; and according to the predicted energy efficiency ratio of each water chilling unit, the operation states of the multiple water chilling units are determined.

Description

Chiller air conditioning system and control method thereof

[0001] This application claims priority to Chinese patent application No. 202211055081.6 filed on August 31, 2022, and priority to Chinese patent application No. 202211081826.6 filed on September 5, 2022, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present disclosure relates to the technical field of chillers, and in particular to a chiller air-conditioning system and a control method thereof. Background Art

[0003] With the continuous improvement of industrial level, water chiller air conditioning system has been gradually applied in various industries. Water chiller air conditioning system can realize cooling or heating to meet the needs of industry and consumers.

[0004] Summary of the Invention

[0005] On the one hand, a chiller air-conditioning system is provided. The chiller air-conditioning system includes a plurality of chillers and a controller. The plurality of chillers share a water circuit, and the refrigerant flow circuits of the plurality of chillers are independent of each other. Each of the plurality of chillers includes at least one compressor, a condenser, a throttling device, and an evaporator. The at least one compressor is configured to compress the refrigerant so that the low-pressure refrigerant is compressed to form a high-pressure refrigerant; the condenser is configured to condense the gaseous refrigerant into a liquid refrigerant and perform heat exchange with the cooling water. The throttling device is also configured to control the flow rate and pressure of the refrigerant flowing through the throttling device; and the evaporator is configured to evaporate the liquid refrigerant into a gaseous refrigerant and perform heat exchange with the chilled water. The compressor, the condenser, the throttling device and the evaporator are connected in sequence to form a refrigerant cycle; the controller is configured to: establish a performance model of the chiller; the performance model of the chiller is related to the operating data of the chiller; calculate the target parameters of each of the multiple chillers under multiple working conditions; the multiple working conditions are different from each other, and the number of open chillers under the multiple working conditions is different; based on the performance model of the chiller and at least one of the target parameters of each chiller, calculate the predicted energy efficiency ratio of each chiller; based on the predicted energy efficiency ratio of each chiller, determine the operating status of the multiple chillers; the operating status of the chiller refers to whether the chiller is turned on or off; and control the operation of the multiple chillers based on the determined operating status of the multiple chillers.

[0006] On the other hand, a control method for a chiller air-conditioning system is provided. The chiller air-conditioning system includes a plurality of chillers and a controller. The plurality of chillers share a water circuit, and the refrigerant flow circuits of the plurality of chillers are independent of each other. Each of the plurality of chillers includes at least one compressor, a condenser, a throttling device and an evaporator. The condenser is configured to condense the gaseous refrigerant into a liquid refrigerant and perform heat exchange with the cooling water. The evaporator is configured to evaporate the liquid refrigerant into a gaseous refrigerant and perform heat exchange with the chilled water. The compressor, the condenser, the throttling device and the evaporator are connected in sequence to form a refrigerant cycle. It is configured to control the operation of the plurality of chillers. The method includes: calculating an average load rate of each of the plurality of chillers under a plurality of working conditions; the plurality of working conditions are different from each other, and the number of openings of the plurality of chillers under the plurality of working conditions is different; calculating an evaporation temperature and a condensation temperature of each chiller under the plurality of working conditions; calculating a first weight corresponding to each chiller under the plurality of working conditions based on the evaporation temperature and the condensation temperature of each chiller; the first weight is related to the temperature difference between the evaporation temperature and the condensation temperature; calculating a first weight corresponding to each chiller under the plurality of working conditions based on the evaporation temperature and the condensation temperature of each chiller; the first weight is related to the temperature difference between the evaporation temperature and the condensation temperature; calculating a first weight according to a preset performance model of the chiller and the temperature difference between each chiller under the plurality of working conditions. The evaporating temperature and condensing temperature of each chiller are calculated, and the predicted energy efficiency ratio of each chiller under the multiple operating conditions is calculated; the performance model characterizes the relationship between the performance coefficient, the average cooling load rate and the first weight; there is a preset relationship between the predicted energy efficiency ratio and the performance coefficient, the evaporating temperature and the condensing temperature; according to the predicted energy efficiency ratio of each chiller under the multiple operating conditions, the operating status of the multiple chillers is determined; the operating status of the chiller refers to whether the chiller is turned on or off; according to the determined operating status of the multiple chillers, the operation of the multiple chillers is controlled. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG1 is a block diagram of a chiller air conditioning system according to some embodiments;

[0008] FIG2 is a structural diagram of a chiller according to some embodiments;

[0009] FIG3 is a block diagram of a chiller according to some embodiments;

[0010] FIG4 is a flow chart of steps performed by a controller according to some embodiments;

[0011] FIG5 is another flow chart of steps performed by a controller according to some embodiments;

[0012] FIG6 is another flow chart of steps performed by a controller according to some embodiments;

[0013] FIG7 is another flow chart of steps performed by a controller according to some embodiments;

[0014] FIG8 is a line graph showing actual energy efficiency ratio and predicted energy efficiency ratio of a multi-head water unit according to some embodiments;

[0015] FIG9 is a line graph showing the relative error between the actual energy efficiency ratio and the predicted energy efficiency ratio of a multi-head water unit according to some embodiments;

[0016] FIG10 is another flow chart of steps performed by a controller according to some embodiments;

[0017] FIG11 is a statistical diagram of cooling load requirements at sample points of a chiller air conditioning system according to some embodiments;

[0018] FIG12 is a statistical diagram of chilled water supply temperatures at sample points of a chiller air conditioning system according to some embodiments;

[0019] FIG13 is a statistical diagram of cooling water return temperature at sample points of a chiller air conditioning system according to some embodiments;

[0020] FIG14 is a statistical diagram of the number of control consoles at sample points of a chiller air conditioning system according to some embodiments;

[0021] FIG15 is a statistical diagram of predicted energy efficiency ratios of sample points of a chiller air conditioning system according to some embodiments. DETAILED DESCRIPTION

[0022] The following will be combined with the accompanying drawings to clearly and completely describe some embodiments of the present disclosure. Obviously, the embodiments described are only some embodiments of the present disclosure, not all embodiments. Based on the embodiments provided by the present disclosure, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of the present disclosure.

[0023] Unless the context requires otherwise, throughout the specification and claims, the term "comprise" and its other forms, such as the third person singular form "comprises" and the present participle form "comprising", are to be interpreted as open and inclusive, that is, "including, but not limited to". In the description of the specification, the terms "one embodiment", "some embodiments", "exemplary embodiments", "example", "specific example" or "some examples" are intended to indicate that the particular features, structures, materials or characteristics associated with the embodiment or example are included in at least one embodiment or example of the present disclosure. The schematic representation of the above terms does not necessarily refer to the same embodiment or example. In addition, the particular features, structures, materials or characteristics may be included in any one or more embodiments or examples in any appropriate manner.

[0024] In the following, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present disclosure, unless otherwise specified, "plurality" means two or more.

[0025] When describing some embodiments, the word "connected" and its derivatives may be used. The term "connected" should be understood broadly. For example, "connected" can mean fixed, removable, or integrated; it can be directly connected or indirectly connected through an intermediary. The embodiments disclosed herein are not necessarily limited to the contents of this document.

[0026] The use of "adapted to" or "configured to" herein is intended to be open and inclusive language that does not exclude devices adapted or configured to perform additional tasks or steps.

[0027] Typically, a chiller air-conditioning system includes at least one chiller. In order to control the energy efficiency of the chiller air-conditioning system, a performance model needs to be established to control the chiller so that the chiller air-conditioning system has good energy efficiency.

[0028] For the performance model of a chiller that includes one compressor, it can be modeled based on the data of the equipment (such as thermodynamic parameters such as temperature and pressure), or it can be modeled through machine learning. However, for a multi-head chiller with multiple compressors, the accuracy of the established performance model is poor. Therefore, when the multi-head chiller is controlled using the established performance model, the energy-saving effect of the multi-head chiller is poor, and thus the energy efficiency of the chiller air-conditioning system is poor. In addition, before the chiller system is delivered, a large number of operating tests need to be done to try to improve the energy-saving effect of the chiller system, which affects the delivery time of the product and wastes experimental resources.

[0029] The poor accuracy of multi-head chiller performance models stems from the fact that they are typically treated as a single-head chiller system. The system is then directly modeled using the same approach as single-head chillers, by collecting parameters from each compressor and superimposing them. However, since the performance of a multi-head chiller is not linearly related to that of a single-head chiller—for example, multiple compressors may affect each other—the fitted parameters in the performance model built using directly superimposed parameters may be inaccurate, making it difficult to obtain an energy efficiency ratio that matches actual conditions. In some approaches, a white box model is used to model multi-head chillers. For example, a performance model is built based solely on theoretical chiller data. This makes it difficult to obtain an energy efficiency ratio that matches actual conditions. In other approaches, a black box model is used to model multi-head chillers. For example, a performance model is built based solely on collected chiller operating data. However, due to the limited scope of the collected data, the model accuracy is poor.

[0030] In this case, the chiller air-conditioning system is controlled according to the performance model established in the above manner, and the energy efficiency of the chiller air-conditioning system is relatively poor.

[0031] To address the aforementioned issues, some embodiments of the present disclosure provide a chiller air conditioning system 100. In this chiller air conditioning system 100, a controller establishes performance models for both a single chiller and a multi-head chiller based on a gray box model. The controller utilizes these established models to control the chiller air conditioning system 100, thereby achieving a high energy efficiency ratio. It will be appreciated that the gray box model herein includes theoretical data for the chiller as well as collected data.

[0032] FIG1 is a block diagram of a chiller air conditioning system according to some embodiments.

[0033] As shown in Figure 1, the chiller air-conditioning system 100 includes a plurality of chillers 101. For example, the chiller air-conditioning system 100 includes a first chiller 101, a second chiller 101... and an Nth chiller 101. Here, N is greater than 1 (N>1), and N is a natural number. The chiller 101 may include a compressor 1, and the chiller 101 may be referred to as a single-head chiller. The chiller 101 may also include a plurality of compressors 1, and the chiller 101 may be referred to as a multi-head chiller. Here, the multi-head chiller may be understood to be composed of a plurality of single-head chillers. The compressor 1 is configured to compress the refrigerant so that the low-pressure refrigerant is compressed to form a high-pressure refrigerant.

[0034] For example, common single-head chiller capacities include 125 tons of Refrigeration (RT), 150 tons, 180 tons, and 200 tons. A 400-ton multi-head chiller can be composed of two 200-ton single-head chillers; a 500-ton multi-head chiller can be composed of a 200-ton single-head chiller and two 150-ton single-head chillers.

[0035] It should be noted that the single-head chillers in a multi-head chiller can share a water flow path, and the multiple chillers 101 in the chiller air-conditioning system 100 can use one water flow path, while the refrigerant flow paths (such as fluorine paths) of the multiple chillers 101 are independent of each other.

[0036] FIG2 is a structural diagram of a chiller according to some embodiments.

[0037] As shown in Figure 2, chiller 101 includes a compressor 1 and a condenser 2. Compressor 1 is configured to compress refrigerant, thereby compressing low-pressure refrigerant into high-pressure refrigerant. The outlet of compressor 1 is connected to the inlet of condenser 2. Condenser 2 is configured to condense gaseous refrigerant into liquid refrigerant and exchange heat with cooling water.

[0038] In some embodiments, as shown in FIG2 , the chiller 101 further includes a throttling device 3 and an evaporator 4. The evaporator 4 is configured to evaporate the liquid refrigerant into a gaseous refrigerant and perform heat exchange with the chilled water. The throttling device 3 is connected to the outlet of the condenser 2 and is configured to control the flow rate and pressure of the refrigerant flowing through the throttling device 3 to expand the liquid refrigerant into a low-pressure liquid refrigerant. The compressor 1, condenser 2, throttling device 3, and evaporator 4 are sequentially connected through pipelines to form a refrigerant cycle.

[0039] During cooling, compressor 1 compresses low-temperature, low-pressure refrigerant gas into high-temperature, high-pressure refrigerant gas, which is then discharged into condenser 2. In condenser 2, the high-temperature, high-pressure refrigerant gas exchanges heat with the outdoor airflow, releasing heat. This heat is then carried by the airflow into the outdoor ambient air, causing the refrigerant to undergo a phase change and condense into a liquid or gas-liquid two-phase refrigerant. The refrigerant then flows out of condenser 2 and enters throttling element 3, where it is cooled and reduced in pressure to become low-temperature, low-pressure refrigerant. The low-temperature, low-pressure refrigerant then enters evaporator 4, where it absorbs heat from the chilled water in evaporator 13 and evaporates, lowering the temperature of the chilled water in evaporator 4 and achieving a cooling effect. The evaporated refrigerant, now a low-temperature, low-pressure refrigerant gas, flows back into compressor 1, achieving refrigerant recycling. Evaporator 4 is also connected to the user end. After the temperature of the chilled water in evaporator 4 is lowered, it enters the user end. The chilled water in evaporator 4 can be replenished by the user end.

[0040] The chilled water in chiller 101 enters evaporator 4, where it absorbs the cooling energy from the evaporating refrigerant, lowering its temperature and turning it into cold water. The chilled water then flows through the water distributor and into the surface cooler or cooling coil, where it exchanges heat with the user's air (e.g., indoor air) before returning to chiller 101 for circulation.

[0041] In some embodiments, the chiller 101 further includes a cold water circuit through which cooling water (also known as coolant) circulates. During the operation of the chiller 101, the components generate a large amount of heat. If this heat is not removed promptly, excessive temperatures can easily damage the components. By providing a cold water circuit and allowing cooling water to flow through the components in the chiller 101, the heat generated by the components can be transferred to the cooling water. This allows the cooling water to remove the heat and cool the components.

[0042] In some embodiments, the heat exchange process of the chiller 101 includes four steps: ① heat exchange between chilled water and the fluid in the cooling environment (e.g., air); ② heat exchange between chilled water and the refrigerant in the evaporator 4; ③ heat exchange between cooling water and the refrigerant in the condenser 2; and ④ heat exchange between cooling water and air in the cooling tower.

[0043] In some embodiments, the compressor 1 may be a magnetically levitated centrifugal compressor.

[0044] In some embodiments, the throttling element 3 may be an electronic expansion valve, a pressure reducer, etc.

[0045] In some embodiments, as shown in FIG1 , the chiller air conditioning system 100 further includes a controller 5. The controller 5 is configured to control the operation of various components in the chiller air conditioning system 100 so that the components of the chiller air conditioning system 100 operate to achieve predetermined functions of the chiller air conditioning system 100.

[0046] For example, the controller 5 is a central processing unit (CPU), a general-purpose processor, a network processor (NP), a digital signal processor (DSP), a microcontroller unit (MCU), or any combination thereof.

[0047] FIG3 is a flow chart of steps performed by a controller according to some embodiments.

[0048] In some embodiments, as shown in FIG3 , the controller 5 is configured to perform steps 11 to 16 .

[0049] In step 11, the average load rate PLR ​​of each chiller 101 in the plurality of chillers 101 under the plurality of working conditions is calculated. (i,j) .

[0050] The multiple operating conditions are different from each other, and the number of opened chillers 101 is different under the multiple operating conditions.

[0051] The chiller air conditioning system 100 is classified into various operating conditions based on the number of chillers 101 that are activated. For example, as shown in FIG1 , the chiller air conditioning system 100 includes N chillers 101. The first operating condition indicates that one chiller 101 is activated, the second operating condition indicates that two chillers 101 are activated, the third operating condition indicates that three chillers 101 are activated, and so on, the Nth operating condition indicates that N chillers 101 are activated.

[0052] The controller 5 can calculate the average load rate PLR ​​of each chiller 101 under different working conditions according to formula (1): (i,j) .

[0053] Here, i represents the i-th working condition, j represents the j-th chiller 101 that is turned on, and Q f is the cooling load demand of the chiller air conditioning system 100, Q ch(j) is the rated cooling load of the j-th chiller 101 , and n is the number of chillers 101 turned on in the chiller air-conditioning system 100 .

[0054] It should be noted that the controller 5 can calculate the required cooling load Q of the chiller air conditioning system 100 according to formula (2): f .Q f =Q p ×△C (2)

[0055] Here, Q pIt refers to the water flow in the main pipe of the refrigeration room, and △C refers to the temperature difference between the supply and return water. Of course, the required cooling load Q can be calculated by other methods. f , which is not limited in this disclosure. Here, the main pipeline is the main pipeline formed by the return of the chilled water pipeline and the cooling water pipeline. The temperature difference between the supply and return water refers to the supply water temperature difference on the main pipeline.

[0056] In this way, the controller 5 can calculate the average load rate PLR ​​of each chiller 101 under multiple working conditions. (i,j) .

[0057] In some embodiments, the chiller air conditioning system 100 includes two 200-ton chillers 101 as an example for description.

[0058] Under the first operating condition (i.e., one chiller 101 is turned on), the first average load rate PLR ​​of the first chiller 101 is calculated according to formula (1): (1,1) and the second average load rate PLR ​​of the second chiller 101 (1,2) Here, the first average load rate PLR (1,1) and the second average load rate PLR (1,2) The calculation process of PLR can refer to the following formulas (101) and (102). (1,1) =(Q f / 1) / Q ch(1) (101) PLR (1,2) =(Q f / 1) / Q ch(2) (102)

[0059] Under the second operating condition (i.e., both chillers 101 are turned on), the third average load rate PLR ​​of the first chiller 101 is calculated according to formula (1): (2,1) and the fourth average load rate PLR ​​of the second chiller 101 (2,2) Here, the third average load rate PLR (2,1) and the fourth average load factor PLR (2,2) The calculation process of PLR can refer to the following formulas (103) and (104). (2,1) =(Q f / 2) / Q ch(1) (103) PLR (2,2) =(Q f / 2) / Q ch(2) (104)

[0060] Here, since the two chillers 101 are 200 ton chillers 101, and the rated cooling load Q of the first chiller 101 isch(1) The rated cooling load Q of the second chiller 101 ch(2) Same (Q ch(1) =Q ch(2) ), therefore, the first average load rate PLR (1,1) and the second average load rate PLR (1,2) Same (PLR (1,1) =PLR (1,2) ), the third average load rate PLR (2,1) and the fourth average load factor PLR (2,2) Same (PLR (2,1) =PLR (2,2) ).

[0061] In other embodiments, the chiller air-conditioning system 100 is described as including a 200-ton chiller 101 and a 150-ton chiller 101 as an example.

[0062] Under the first operating condition (i.e., one chiller 101 is turned on), the first average load rate PLR ​​of the first chiller 101 is calculated according to formula (1): (1,1) and the second average load rate PLR ​​of the second chiller 101 (1,2) Here, the first average load rate PLR (1,1) and the second average load rate PLR (1,2) The calculation process of PLR can refer to the following formulas (105) and (106). (1,1) =(Q f / 1) / Q ch(1) (105) PLR (1,2) =(Q f / 1) / Q ch(2) (106)

[0063] Under the second operating condition (i.e., both chillers 101 are turned on), the third average load rate PLR ​​of the first chiller 101 is calculated according to formula (1): (2,1) and the fourth average load rate PLR ​​of the second chiller 101 (2,2) Here, the third average load rate PLR (2,1) and the fourth average load factor PLR (2,2) The calculation process of PLR can refer to the following formulas (107) and (108). (2,1) =(Q f / 2) / Q ch(1) (107) PLR (2,2) =(Q f1 / 2) / Q ch(2) (108)

[0064] Here, since the two chillers 101 are a 150-ton chiller 101 and a 200-ton chiller 101, and the rated cooling load Q of a 200-ton chiller 101 is ch(1) The rated cooling load Q of a 150-ton chiller 101 is ch(2) Not the same (Q ch(1) ≠Q ch(2) ), therefore, the first average load rate PLR (1,1) and the second average load rate PLR (1,2) Different (PLR (1,1) ≠PLR (1,2) ), the third average load rate PLR (2,1) and the fourth average load factor PLR (2,2) Different (PLR (2,1) ≠PLR (2,2) ).

[0065] Similarly, when the chiller air conditioning system 100 includes three chillers 101, for the first working condition, the average load rate PLR ​​of each of the three chillers 101 can be calculated. (i,j) , that is, the first average load rate PLR (1,1) , the second average load rate PLR (1,2) and the fifth average load factor PLR (1,3) For the second working condition, the average load rate of each of the three chillers 101 can be calculated, that is, the third average load rate PLR. (2,1) , the fourth average load rate PLR (2,2) and the sixth average load factor PLR (2,3) For the third working condition, the average load rate of each of the three chillers 101 can be calculated, that is, the seventh average load rate PLR. (3,1) 、8th average load rate PLR (3,2) and the ninth average load factor PLR (3,3) .

[0066] Thus, through step 11, the controller 5 can calculate the average load rate PLR ​​of each chiller 101 under multiple working conditions. (i,j) .

[0067] In step 12, the evaporation temperature T of each chiller 101 under multiple working conditions is calculated. e(i,j) and condensation temperature T c(i,j) .

[0068] The first relationship and the second relationship are preset to determine the evaporation temperature T of each chiller 101 under multiple working conditions.e(i,j) and condensation temperature T c(i,j) .

[0069] The first relationship represents the relationship between the evaporation temperature and the average cooling load rate PLR, the chilled water supply temperature te, and the cooling water supply and return temperature difference ΔT corresponding to the chiller 101 operating at rated load. e,tem , and the relationship between the corresponding condenser heat exchange temperature difference ΔT when the chiller 101 operates at rated load e,exc (As shown in formula (3)). The second relationship represents the relationship between the condensing temperature and the average cooling load rate PLR, the cooling water return temperature tc, and the corresponding chilled water supply and return temperature difference ΔT when the chiller 101 is running at rated load. c,tem , and the relationship between the corresponding evaporator heat exchange temperature difference ΔT when the chiller 101 operates at rated load c,exc (As shown in formula (4)).

[0070] It should be noted that when calculating the evaporation temperature T e(i,j) and condensation temperature T c(i,j) During the process, the above parameters need to be obtained.

[0071] In some embodiments, the corresponding cooling water supply and return water temperature difference ΔT when the chiller 101 operates at rated load is e,tem , the corresponding evaporator heat exchange temperature difference ΔT when the chiller 101 is running at rated load c,exc , the corresponding condenser heat exchange temperature difference ΔT when the chiller 101 is running at rated load e,exc , the corresponding chilled water supply and return water temperature difference ΔT when the chiller 101 operates at rated load c,tem The values ​​can be set to 5° C. respectively, so as to calculate the evaporation temperature Te and the condensation temperature Tc. Of course, the above four values ​​can also be set to other values ​​according to requirements, and the present disclosure does not limit this.

[0072] In this way, the controller 5 can calculate the evaporation temperature T of each chiller 101 under multiple working conditions based on the evaporation temperature model (first relationship) and the condensation temperature model (second relationship). e(i,j) and condensation temperature T c(i,j) .

[0073] In some embodiments, the chiller air conditioning system 100 includes two 200-ton chillers 101 as an example for description.

[0074] Under the first working condition, the controller 5 operates according to the first average load rate PLR (1,1) , the first chilled water supply temperature te (1,1) , the first cooling water supply and return water temperature difference ΔT e,tem(1,1), first condenser heat exchange temperature difference △T e,exc(1,1) , calculate the evaporation temperature Te of the first chiller by formula (3) (1,1) Furthermore, the controller 5 adjusts the load according to the first average load rate PLR. (1,1) , first cooling water supply temperature tc (1,1) , the first chilled water supply and return water temperature difference ΔT c,tem(1,1) , first evaporator heat exchange temperature difference △T c,exc(1,1) , calculate the condensing temperature Tc of the first chiller 101 by formula (4) (1,1) .

[0075] Under the first working condition, the controller 5 operates according to the second average load rate PLR (1,2) , Second chilled water supply temperature te (1,2) , Second cooling water supply and return water temperature difference ΔT e,tem(1,2) , the second condenser heat exchange temperature difference △T e,exc(1,2) , calculate the evaporation temperature Te of the second chiller by formula (3) (1,2) Furthermore, the controller 5 calculates the load according to the second average load rate PLR. (1,2) , Second cooling water supply temperature tc (1,2) , the first chilled water supply and return water temperature difference ΔT c,tem(1,2) , first evaporator heat exchange temperature difference △T c,exc(1,1) , calculate the condensing temperature Tc of the second 200-ton chiller using formula (4) (1,2) .

[0076] It should be noted that the first average load rate PLR (1,1) is the average load rate under the first working condition, the first chilled water supply temperature te (1,1) is the chilled water supply temperature under the first working condition, the first cooling water supply and return temperature difference ΔT e,tem(1,1) is the cooling water supply and return temperature difference under the first working condition, and the first condenser heat exchange temperature difference △T e,exc(1,1) is the condenser heat exchange temperature difference under the first working condition. The second average load rate PLR (1,2) is the average load rate under the second working condition, and the second chilled water supply temperature te (1,2) is the chilled water supply temperature under the second working condition, and the second cooling water supply and return temperature difference ΔT e,tem(1,2) is the cooling water supply and return temperature difference under the second working condition, and the second condenser heat exchange temperature difference △T e,exc(1,2) is the condenser heat exchange temperature difference under the second working condition.

[0077] Since the first average load rate PLR (1,1) and the second average load rate PLR (1,2) Same (PLR (1,1) =PLR (1,2)), therefore, at the first chilled water supply temperature te (1,1) and the second chilled water supply temperature te (1,2) Same, and the first cooling water return temperature tc (1,1) and the second cooling water return temperature tc (1,2) Under the same conditions, the condensing temperature Tc of the first chiller 101 is (1,1) The condensing temperature Tc of the second chiller 101 (1,2) Same (Tc (1,1) =Tc (1,2) ). The evaporation temperature Te of the first chiller 101 (1,1) and the evaporation temperature Te of the second chiller 101 (1,2) Same (Te (1,1) =Te (1,2) ).

[0078] In other embodiments, the chiller air-conditioning system 100 includes a 200-ton chiller 101 and a 150-ton chiller 101 as an example for description.

[0079] Under the first working condition, the controller 5 operates according to the first average load rate PLR (1,1) , the first chilled water supply temperature te (1,1) , the first cooling water supply and return water temperature difference ΔT e,tem(1,1) , first condenser heat exchange temperature difference △T e,exc(1,1) , calculate the evaporation temperature Te of the first chiller 101 by formula (3) (1,1) .

[0080] The controller 5 is configured to calculate the first average load rate PLR. (1,1) , first cooling water supply temperature tc (1,1) , the first chilled water supply and return water temperature difference ΔT c,tem (1,1) , first evaporator heat exchange temperature difference △T c,exc(1,1) , calculate the condensing temperature Tc of the first chiller 101 by formula (4) (1,1) .

[0081] Under the first working condition, the controller 5 operates according to the second average load rate PLR (1,2) , Second chilled water supply temperature te (1,2) , Second cooling water supply and return water temperature difference ΔT e,tem(1,2) , the second condenser heat exchange temperature difference △T e,exc(1,2) , calculate the evaporation temperature Te of the second chiller 101 by formula (3) (1,2) .

[0082] The controller 5 calculates the load according to the second average load rate PLR. (1,2), Second cooling water supply temperature tc (1,2) , the first chilled water supply and return water temperature difference ΔT c,tem(1,2) , first evaporator heat exchange temperature difference △T c,exc(1,1) , calculate the condensing temperature Tc of the second chiller 101 by formula (4) (1,2) .

[0083] Thus, the first average load factor PLR (1,1) and the second average load rate PLR (1,2) Different (PLR (1,1) ≠PLR (1,2) ), then at the first chilled water supply temperature te (1,1) and the second chilled water supply temperature te (1,2) Same, and the first cooling water return temperature tc (1,1) and the second cooling water return temperature tc (1,2) Under the same conditions, the condensing temperature Tc of a 200-ton chiller 101 is (1,1) The condensing temperature Tc of a 150-ton chiller 101 (1,2) Also different (Tc (1,1) ≠Tc (1,2) ), the evaporation temperature Te of a 200-ton chiller 101 (1,1) The evaporation temperature Te of a 150-ton chiller 101 is (1,2) Also different (Te (1,1) ≠Te (1,2) ).

[0084] The evaporation temperature T of each chiller 101 under other working conditions e(i,j) and condensation temperature T c(i,j) The calculation process is similar to the above and will not be described here.

[0085] Thus, through step 12, the controller 5 can calculate the evaporation temperature Te of each chiller 101 under multiple working conditions. (i,j) and condensation temperature Tc (i,j) .

[0086] In step 13, the evaporation temperature Te of each chiller 101 under different working conditions is determined. (i,j) And condensation temperature Tc (i,j) , calculate the first weight dT corresponding to each chiller 101 under multiple working conditions (i,j) .

[0087] Weight dT (i,j) and evaporation temperature Te (i,j) and condensation temperature Tc (i,j) The temperature difference between them.

[0088] For example, the controller 5 calculates the first weight dT corresponding to each chiller 101 under multiple working conditions according to formula (5): (i,j) .

[0089] Here, T c Indicates the condensation temperature, T e Indicates the evaporation temperature, △T max represents the condensing temperature T of the chiller 101 c and evaporation temperature T e The maximum temperature difference between min represents the condensing temperature T of the chiller 101 c and evaporation temperature T e Minimum temperature difference between.

[0090] In some embodiments, the condensing temperature T of the chiller 101 is preset. c and evaporation temperature T e The maximum temperature difference between max The condensing temperature T of the chiller 101 is set to 45°C. c and evaporation temperature T e Minimum temperature difference △T min is 15°C, so that the controller 5 calculates the first weight dT using formula (5) (i,j) .

[0091] Of course, the condensing temperature T of the chiller 101 c and evaporation temperature T e Minimum temperature difference △T min , the condensing temperature T of the chiller 101 c and evaporation temperature T e The maximum temperature difference between max It can also be set to other values, or it can be set to the condensing temperature T of the chiller 101. c and evaporation temperature T e Other coefficients related to the temperature difference are not limited in this disclosure.

[0092] In this case, the controller 5 can calculate the first weight dT corresponding to each chiller 101 under various working conditions according to formula (5): (i,j) .

[0093] In some embodiments, the chiller air conditioning system 100 is described as including two 200-ton chillers 101 .

[0094] For the first working condition, the controller 5 controls the evaporation temperature Te of the first chiller 101. (1,1), the condensing temperature Tc of the first chiller 101 (1,1) , calculate the first weight dT of the first chiller 101 by formula (5) (1,1) .

[0095] For the first working condition, the controller 5 sets the evaporation temperature Te of the second chiller 101 according to the evaporation temperature Te of the second chiller 101. (1,2) , the second chiller 101 condensing temperature Tc (1,2) , calculate the first weight dT of the second chiller 101 by formula (5) (1,2) .

[0096] In the first working condition, the evaporation temperature Te of the first chiller 101 is (1,1) Equal to the evaporation temperature Te of the second chiller 101 (1,2) (Te (1,1) =Te (1,2) ), the condensing temperature Tc of the first chiller 101 (1,1) Equal to the condensing temperature Tc of the second chiller 101 (1,2) (Tc (1,1) =Tc (1,2) ), therefore, the first weight dT of the first chiller 101 (1,1) and the first weight dT of the second chiller 101 (1,2) Same (dT (1,1) =dT (1,2) ).

[0097] For another example, the chiller air conditioning system 101 includes a 200-ton chiller and a 150-ton chiller.

[0098] For the first working condition, the controller 5 controls the evaporation temperature Te of the first chiller 101. (1,1) , the condensing temperature Tc of the first chiller 101 (1,1) , calculate the first weight dT of the first chiller 101 by formula (5) (1,1) .

[0099] For the first working condition, the controller 5 controls the evaporation temperature Te of the second chiller 101. (1,2) , the condensing temperature Tc of the second chiller 101 (1,2) , calculate the first weight dT of the second chiller 101 by formula (5) (1,2) .

[0100] In the first working condition, the evaporation temperature Te of the first chiller 101 is (1,1) and the evaporation temperature Te of the second chiller 101 (1,2) Different (Te(1,1) ≠Te (1,2) ), the condensing temperature Tc of the first chiller 101 (1,1) The condensing temperature Tc of the second chiller 101 (1,2) Different (Tc (1,1) ≠Tc (1,2) ), therefore, the first weight dT of the first chiller 101 (1,1) and the first weight dT of the second chiller 101 (1,2) Different (dT (1,1) ≠dT (1,2) ).

[0101] The first weight dT under other working conditions (i,j) The calculation process is similar to the above and will not be described here.

[0102] Thus, through step 13, the controller 5 can calculate the first weight dT corresponding to each chiller 101 under multiple working conditions. (i,j) .

[0103] In step 14, according to the preset performance model of the chiller 101 and the calculated evaporation temperature Te of each chiller 101 under multiple working conditions, (i,j) And condensation temperature Tc (i,j) , calculate the predicted energy efficiency ratio COP of each chiller 101 under multiple operating conditions pre(i,j) .

[0104] If chiller 101 is a single-head chiller, the performance model of the single-head chiller is the performance model of chiller 101. If chiller 101 is a multi-head chiller, the performance model of chiller 101 can be obtained based on the performance models of each single-head chiller in the multi-head chiller. In other words, the performance model of the chiller includes at least one of the performance model of the single-head chiller and the performance model of the multi-head chiller.

[0105] It should be noted that the performance model for a single-head chiller can be built using device-based data or machine learning. Of course, the performance model for a multi-head chiller can also be built by collecting data from the entire system and using the same modeling methods as for a single-head chiller.

[0106] The following description will be made by taking the chiller 101 as a multi-head chiller as an example.

[0107] FIG4 is another flow chart illustrating steps performed by a controller according to some embodiments.

[0108] In some embodiments, as shown in FIG. 4 , the controller 5 is further configured to execute steps 141 to 143 .

[0109] In step 141 , operating data of the chiller 101 is collected.

[0110] The collected operating data of the chiller 101 include: the evaporation temperature Te of each single head chiller in the chiller 101 k , condensation temperature Tc k And the operating load L k Here, k represents the kth single-head chiller, and k is a natural number, k is greater than or equal to 1 (1≤k). It should be noted that, in the case where the chiller 101 is a multi-head chiller, the evaporation temperature Te k , condensation temperature Tc k and the operating load L k Refers to the parameters of each single-head chiller in the chiller 101. In the case where the chiller 101 is a single-head chiller, the evaporation temperature Te k , condensation temperature Tc k And the operating load L k Refers to the parameters of the chiller 101.

[0111] In the case where the multi-head chiller includes m single-head chillers, m is greater than or equal to k (k≤m), where m>1 and m is a natural number.

[0112] In addition, it is also necessary to collect other operating data of the single-head chiller in the chiller 101 to eliminate the collected data (evaporation temperature Te k , condensation temperature Tc k and the operating load L k ), thereby improving the reliability of the collected data and also facilitating accurate establishment of a performance model of the chiller 101.

[0113] In some embodiments, the collected operating data of the chiller 101 also includes: the chilled water supply temperature T e-out , Chilled water return temperature T e-in , Chilled water flow Q e , Cooling water inlet temperature T c-in , cooling water outlet temperature T c-out , cooling water flow Q c , the operating power P of each single head chiller in chiller 101 i .

[0114] FIG5 is another flow chart of steps performed by a controller according to some embodiments.

[0115] In this case, as shown in FIG5 , the controller 5 is further configured to execute steps 1411 to 1416:

[0116] In step 1411, according to the chilled water return temperature T e-in , Chilled water supply temperature T e-out , Chilled water flow Q e And the specific heat capacity c of water, calculate the current cooling capacity Q of the chiller 101 chw .

[0117] For example, the controller 5 calculates the current cooling capacity Q of the chiller 101 according to formula (201): chw .Q chw =c×Q e ×(T e-in -T e-out ) (201)

[0118] It should be noted that other methods can also be used to calculate the current cooling capacity Q of the chiller 101 chw .

[0119] In step 1412, according to the cooling water outlet temperature T c-out , Cooling water inlet temperature T c-in , cooling water flow Q c And the specific heat capacity c of water, calculate the current heat rejection Q of the chiller 101 cw .

[0120] For example, the controller 5 calculates the heat rejection Q of the chiller 101 according to formula (202): cw .Q cw =c×Q c ×(T c-in -T c-out ) (202)

[0121] In step 1413, according to the current cooling capacity Q of the chiller 101 chw , the current heat rejection Q of chiller 101 cw and the operating power Pi of each single-head chiller in the chiller unit 101, and calculate the energy balance coefficient γ.

[0122] For example, the controller 5 calculates the energy balance coefficient γ of the chiller 101 according to formula (203).

[0123] Here, m represents the number of single-head chillers, It represents the sum of the operating powers of all single-head chillers in chiller 101.

[0124] In step 1414, it is determined whether the energy balance coefficient γ is greater than a preset value. If yes, step 1415 is executed; if no, step 1416 is executed.

[0125] In step 1415 , it is determined that the collected operating data is an abnormal value.

[0126] In step 1416 , it is determined that the collected operating data is a normal value.

[0127] Here, the preset value can be preset or changed as needed. For example, the preset value is 10%. If the capacity balance coefficient γ is greater than 10%, the controller 5 determines that the operating data corresponding to the capacity balance coefficient γ is an abnormal value; if the capacity balance coefficient γ is less than or equal to 10%, the controller 5 determines that the operating data corresponding to the capacity balance coefficient γ is a normal value.

[0128] It should be noted that the operating data corresponding to the capacity balance coefficient γ is: the evaporation temperature Te of each single-head chiller in the chiller 101 k , condensation temperature Tc k and the operating load L k .

[0129] In step 142 , the performance model of each single-head chiller in the chiller 101 is determined.

[0130] According to the collected evaporation temperature Te of the single-head chiller k , condensation temperature Tc k , operating load L k , Rated cooling capacity Q des,k and energy efficiency ratio COP k , determine the performance model of the single-head chiller. It should be noted that the data collected here is the operating data of the single-head chiller in order to establish the performance model.

[0131] Here, the performance coefficient DCOP is introduced to characterize the performance model of a single-head chiller. k .

[0132] FIG6 is another flow chart of steps performed by a controller according to some embodiments.

[0133] In some embodiments, as shown in FIG6 , the controller 5 is configured to perform steps 1421 and 1422:

[0134] In step 1421, according to the collected evaporation temperature Te of each single head chiller k , condensation temperature Tc k and energy efficiency ratio COP k , calculate the performance coefficient DCOP of each single head chiller k.

[0135] For example, the controller 5 calculates the performance coefficient DCOP of each single-head chiller through formula (204): k .

[0136] In step 1422, the coefficient of performance DCOP of each single-head chiller is calculated. k , the second weight dT k and load factor PLR k , fit and determine the relationship between the coefficient of performance of each single-head chiller.

[0137] For example, the controller 5 calculates the load rate PLR ​​by formulas (205) and (206): k .

[0138] here, It represents the sum of the operating loads of all single-head chillers, Q k Indicates the cooling capacity of each single-head chiller. k The operating load L of the single-head chiller k And the current cooling capacity Q of the chiller chw Related.

[0139] Furthermore, the controller 5 can calculate the second weight dT corresponding to each single-head chiller according to formula (5): k It should be noted that the second weight dT k It is related to the collected evaporation temperature, the collected condensation temperature, and the temperature difference between the condensation temperature and the evaporation temperature of the single-head chiller.

[0140] Controller 5 fitting performance coefficient DCOP k and load factor PLR k and the second weight dT k The relationship between (such as formula (207)). DCOP k =A k ×PLR k 2 +B k ×PLR k ×dT k +C k ×dT k 2 +D k ×PLR k +E k ×dT k +F k(207)

[0141] Here, A k 、B k 、C k 、D k 、E k and F k is the fitting coefficient. Formula (207) is the relationship between the performance coefficient of the single-head chiller, which is also the performance model of the single-head chiller.

[0142] For example, the fitting coefficients of a 200-ton single-head chiller are A1, B1, C1, D1, E1, and F1, and the cooling load rate is PLR1, and the weight is dT1. Then the performance model of the 200-ton single-head chiller is: DCOP1=A1×PLR1 2 +B1*PLR1×dT1+C1×dT1 2 +D1×PLR1+E1×dT1+F1.

[0143] For example, the fitting coefficients of a 150-ton single-head chiller are A2, B2, C2, D2, E2, and F2, and the cooling load rate is PLR2, and the weight is dT2. Then the performance model of the 150-ton single-head chiller is: DCOP2 = A2 × PLR2 2 +B2×PLR2×dT2+C2*dT2 2 +D2×PLR2+E2×dT2+F2.

[0144] It should be noted that the fitting coefficients of the single-head chillers with different refrigeration tons are different. In addition, in step 14, when the controller 5 calculates the performance coefficient of the chiller 101 according to the performance model of the single-head chiller, the average load rate PLR ​​calculated in step 11 is calculated. (i,j) , the first weight dT calculated in step 13 (i,j) Substitute the load rate PLR ​​respectively k and the second weight dT k Get the performance coefficient.

[0145] In step 143, the performance model of the multi-head chiller is determined based on the determined performance model of each single-head chiller.

[0146] FIG. 7 is another flow chart illustrating steps performed by a controller according to some embodiments.

[0147] In some embodiments, as shown in FIG7 , the controller 5 is configured to perform steps 1431 to 1433:

[0148] In step 1431, according to the performance model of the single-head chiller and the collected evaporation temperature Tek and the collected condensation temperature Tc k Calculate the predicted energy efficiency ratio COP of each single head chiller pre,k .

[0149] For example, controller 5 calculates the predicted energy efficiency ratio COP of each single-head chiller through formula (209): pre,k COP pre,k =DCOP k ×Te k / (Tc k -Te k ) (209)

[0150] In step 1432, the predicted energy efficiency ratio COP of each single-head chiller is calculated. pre,k and cooling capacity Q k , determine the electric power P of the chiller 101 w .

[0151] For example, the controller 5 calculates the electric power P of the chiller 101 according to formula (210): w .

[0152] In step 1433, according to the electric power P w and the current cooling capacity Q of chiller 101 chw , determine the predicted energy efficiency ratio COP of the multi-head chiller pre .

[0153] For example, the controller 5 determines the predicted energy efficiency ratio COP of the chiller 101 (multi-head chiller) by formula (210): pre COP pre =Q cw / P w (210)

[0154] In this way, based on the performance models of multiple single-head chillers, the performance model of the multi-head chiller (Formula 209 to Formula 210) and the predicted energy efficiency ratio COP of the multi-head chiller can be determined. pre For example, when the chiller 101 is a single-head chiller, the predicted energy efficiency ratio COP of the chiller 101 in step 14 is pre(i,j) It can be obtained by formula (209); in the case where the chiller 101 is a multi-head chiller, the predicted energy efficiency ratio COP of the chiller 101 in step 14 is pre(i,j) It can be obtained by formula (210).

[0155] In some embodiments of the present disclosure, a performance model of a large, multi-head chiller with different combinations can be quickly established and optimized based on actual operating data, thereby improving the accuracy of the performance model. Furthermore, this modeling approach reflects the operating conditions of a multi-head chiller based on the characteristics of multiple single-head chillers. Therefore, using this model to control chiller 101 can achieve good energy-saving effects.

[0156] In this paper, a performance model is established based on the operating data of a multi-head chiller and the performance model is verified.

[0157] Table 1

[0158] For example, as shown in Table 1, the cooling capacity of this multi-head chiller is 500 tons, and this 500-ton multi-head chiller consists of one 200-ton single-head chiller and two 150-ton single-head chillers. Table 1 shows the chilled water inlet temperature, chilled water outlet temperature, cooling water inlet temperature, cooling water inlet temperature, cooling water flow rate, total power, total cooling load, and total load factor for this multi-head chiller.

[0159] Table 2

[0160] Table 3

[0161] Table 4

[0162] As shown in Tables 2 to 4, Table 2 shows the operating data of a 200-ton single-head chiller in a 500-ton multi-head chiller. Table 3 shows the operating data of a 150-ton single-head chiller in a 500-ton multi-head chiller. Table 4 shows the operating data of another 150-ton single-head chiller in a 500-ton multi-head chiller.

[0163] Table 5

[0164] In some embodiments, as shown in Table 5, 20 sample points are selected and the controller 5 calculates the predicted energy efficiency ratio COP of a 500-ton multi-head chiller through the above formulas (201) to (210). pre .

[0165] Figure 8 is a line graph showing the actual energy efficiency ratio and predicted energy efficiency ratio of a multi-head water unit according to some embodiments. Figure 9 is a line graph showing the relative error between the actual energy efficiency ratio and predicted energy efficiency ratio of a multi-head water unit according to some embodiments.

[0166] As shown in Figure 8, the actual and predicted EER curves for a 500-ton multi-head water chiller largely overlap. As shown in Figure 9, the relative error between the actual and predicted EERs for a 500-ton multi-head water chiller is small.

[0167] As shown in Figures 8 and 9, the predicted COP of the multi-head chiller pre It is basically the same as the actual energy efficiency ratio COP.

[0168] Table 6

[0169] In this way, the controller 5 can calculate the predicted energy efficiency ratio COP of each chiller 101 under different working conditions according to formula (209) and formula (210): pre(i，j) .

[0170] In some embodiments, the chiller air conditioning system 100 includes two 200-ton chillers 101 as an example.

[0171] For the first working condition, the controller 5 is set according to the first cooling load rate PLR. (1,1) , the first weight dT (1,1) , first evaporation temperature Te (1,1) , first condensation temperature Tc (1,1) And formula (209) calculates the first predicted energy efficiency ratio COP of the first chiller 101 pre(1,1) .

[0172] For the first working condition, the controller 5 is set according to the second cooling load rate PLR. (1,2) , the second weight dT (1,2) , the second evaporation temperature Te (1,2) , second condensation temperature Tc (1,2) And formula (209) calculates the second predicted energy efficiency ratio COP of the second chiller 101 pre(1,2) .

[0173] Thus, due to the first average load rate PLR (1,1) and the second average load rate PLR (1,2) Same (PLR (1,1) =PLR (1,2) ), the first weight dT (1,1) and the second weight dT (1,2) Same (dT (1,1) =dT (1,2) ), the first evaporation temperature Te of the first 200-ton chiller 101 (1,1) The second evaporation temperature Te of the second 200-ton chiller 101 (1,2) Same (Te (1,1) =Te(1,2) ), the first condensing temperature Tc of the first 200-ton chiller 101 (1,1) The second condensing temperature Tc of the second 200-ton chiller 101 (1,2) Same (Tc (1,1) =Tc (1,2) ). Therefore, the first predicted energy efficiency ratio COP pre(1,1) and the second predicted energy efficiency ratio COP pre(1,2) Same (COP pre(1,1) =COP pre(1,2) ).

[0174] For the second working condition, the controller 5 is set according to the third cooling load rate PLR. (2,1) , the third weight dT (2,1) , the third evaporation temperature Te (2,1) , the third condensation temperature Tc (2,1) And formula (209) calculates the third predicted energy efficiency ratio COP of the first chiller 101 pre(2,1) The controller 5 adjusts the cooling load rate PLR ​​according to the fourth cooling load rate PLR. (2,2) , the fourth weight dT (2,2) , the fourth evaporation temperature Te (2,2) , the fourth condensation temperature Tc (2,2) And formula (209) calculates the fourth predicted energy efficiency ratio COP of the second chiller 101 pre(2,2) .

[0175] Thus, due to the third average load rate PLR (2,1) and the fourth average load factor PLR (2,2) Same (PLR (2,1) =PLR (2,2) ), the third weight dT (2,1) and the fourth weight dT (2,2) Same (dT (2,1) =dT (2,2) ), the third evaporation temperature Te of the first 200-ton chiller 101 (2,1) The fourth evaporation temperature Te of the second 200-ton chiller 101 (2,2) Same (Te (2,1) =Te (2,2) ), the third condensing temperature Tc of the first 200-ton chiller 101 (2,1) The condensing temperature Tc of the second 200-ton chiller 101 (2,2) Same (Tc (1,1) =Tc (1,2) ). Therefore, the third predicted energy efficiency ratio COP pre(2,1) and the fourth predicted energy efficiency ratio COP pre(2,2) Same (COPpre(2,1) =COP pre(2,2) ).

[0176] In other embodiments, it is taken as an example that the chiller air conditioning system 100 includes a 200-ton chiller 101 and a 150-ton chiller 101 .

[0177] For the first working condition, the controller 5 is set according to the first cooling load rate PLR. (1,1) , the first weight dT (1,1) , first evaporation temperature Te (1,1) , first condensation temperature Tc (1,1) And formula (209) calculates the first predicted energy efficiency ratio COP of the first chiller 101 pre(1,1) .

[0178] For the first working condition, the controller 5 is set according to the second cooling load rate PLR. (1,2) , the second weight dT (1,2) , the second evaporation temperature Te (1,2) , second condensation temperature Tc (1,2) And formula (209) calculates the second predicted energy efficiency ratio COP of the second chiller 101 pre(1,2) .

[0179] In this way, the first predicted energy efficiency ratio COP pre(1,1) and the second predicted energy efficiency ratio COP pre(1,2) Not necessarily the same.

[0180] For the second working condition, the controller 5 is set according to the third cooling load rate PLR. (2,1) , the third weight dT (2,1) , the third evaporation temperature Te (2,1) , the third condensation temperature Tc (2,1) And formula (209) calculates the third predicted energy efficiency ratio COP of the first chiller 101 pre(2,1) The controller 5 adjusts the cooling load rate PLR ​​according to the fourth cooling load rate PLR. (2,2) , the fourth weight dT (2,2) , the fourth evaporation temperature Te (2,2) , the fourth condensation temperature Tc (2,2) And formula (209) calculates the fourth predicted energy efficiency ratio COP of the second chiller 101 pre(2,2) .

[0181] Thus, the third predicted energy efficiency ratio COP pre(2,1) and the fourth predicted energy efficiency ratio COP pre(2,2) Not necessarily the same.

[0182] Predicted COP of each chiller 101 under other working conditions pre(i,j)The calculation process is similar to the above and will not be described here.

[0183] In step 15, the predicted energy efficiency ratio (COP) of each chiller under multiple operating conditions is calculated. pre(i,j) , determine the operating status of multiple chillers 101 in the chiller air-conditioning system 100.

[0184] Here, the operating state of the chiller 101 refers to whether the chiller 101 is turned on or off.

[0185] In step 16 , the operation of the plurality of chillers 101 is controlled according to the determined operating states of the plurality of chillers 101 .

[0186] Controller 5 predicts the energy efficiency ratio COP by comparing pre,(i,j) to determine whether to turn on or off the corresponding chiller 101 in the chiller air-conditioning system 100, so that the chiller air-conditioning system 100 operates under a condition with relatively high energy efficiency.

[0187] For example, the chiller air conditioning system 100 includes two 200-ton chillers 101. Under the first working condition, the first predicted energy efficiency ratio COP of the first chiller 101 is pre(1,1) The second predicted energy efficiency ratio COP corresponding to the second chiller 101 pre(1,2) Same (COP pre (1,1) =COP pre(1,2) ). Under the second working condition, the third predicted energy efficiency ratio COP corresponding to the first chiller 101 is pre(2,1) The fourth predicted energy efficiency ratio COP corresponding to the second chiller 101 pre(2,2) Same (COP pre(2,1) =COP pre(2,2) ).

[0188] For another example, the chiller air conditioning system 100 includes a 200-ton chiller and a 150-ton chiller 101. Under the first working condition, the first predicted energy efficiency ratio COP corresponding to the 200-ton chiller 101 is pre(1,1) The second predicted energy efficiency ratio COP corresponding to a 150-ton chiller 101 pre(1,2) Under the second working condition, the third predicted energy efficiency ratio COP corresponding to a 200-ton chiller 101 is pre(2,1) The fourth predicted energy efficiency ratio COP corresponding to a 150-ton chiller 101 is pre(2,2) Not necessarily the same.

[0189] The process of comparing and predicting the energy efficiency ratio under other working conditions is similar to the above and will not be described again here. In this way, the chiller air conditioning system 100 can operate at a higher energy efficiency ratio.

[0190] It should be noted that, when the chiller air-conditioning system 100 includes two chillers 101, if the controller 5 calculates that the energy efficiency of turning on both chillers 101 is greater than the energy efficiency of turning on one chiller, the chiller air-conditioning system 100 operates under the operating condition of turning on both chillers 101. In this case, if one chiller 101 is currently operating, it is determined that the second chiller 101 needs to be turned on.

[0191] Similarly, if it is calculated that the energy efficiency of turning on one chiller 101 is greater than the energy efficiency of turning on two chillers 101, the chiller air conditioning system 100 operates under the operating condition of turning on one chiller 101. In this case, if two chillers are currently running, it is determined that one chiller 101 needs to be turned off.

[0192] FIG. 10 is another flow chart illustrating steps performed by a controller according to some embodiments.

[0193] In order to avoid frequent start and stop of the chiller 101, whether to start or stop it also needs to consider the cooling load fluctuation of the chiller air conditioning system 100. Therefore, in some embodiments, as shown in FIG10, step 16 includes steps 161 to 166.

[0194] In step 161 , the load change rate ROC of the cooling load of the chiller air-conditioning system 100 at the previous moment relative to the required cooling load is calculated.

[0195] In step 162, it is determined whether the load change rate ROC reaches the upper limit value ROC1 of the load change rate of the chiller 101 to be started. If "yes", step 163 is executed and the process returns to step 11; if "no", step 166 is executed.

[0196] In step 163 , a chiller 101 in the chiller air-conditioning system 100 is turned on.

[0197] In step 164, it is determined whether the load change rate ROC reaches the upper limit value ROC2 of the load change rate of the chiller 101 to be shut down. If "yes", step 165 is executed and the process returns to step 11; if "no", step 166 is executed.

[0198] In step 165 , one chiller 101 in the chiller air conditioning system 100 is shut down.

[0199] In step 166 , the chiller air-conditioning system 100 is controlled to continue operating in the current operating state.

[0200] When the chiller air conditioning system 100 is running, the controller 5 can determine whether the cooling load has changed dramatically by calculating the load change rate of the cooling load of the chiller air conditioning system 100 at the previous moment relative to the required cooling load.

[0201] The sudden change includes two types of changes: one is a sudden decrease, which requires shutting down the chiller 101; the other is a sudden increase, which requires shutting down the chiller 101.

[0202] If the load change rate ROC reaches the upper limit ROC1 of the load change rate of the chiller 101 to be shut down, it indirectly indicates that the load has decreased sharply within the first preset time period. If the chiller 101 is not shut down, the water temperature cannot be immediately adjusted to the set value within the first preset time period. In other words, the cooling capacity of the chiller air conditioning system 100 cannot be reduced to the required cooling load in a timely manner within the first preset time period, and the corresponding chiller 101 needs to be shut down.

[0203] If the load change rate ROC reaches the upper limit ROC2 of the load change rate of the chiller 101 to be started, it indirectly indicates that the load has increased sharply within the first preset time period. If the chiller 101 is not turned on, the water temperature cannot be immediately adjusted to the set value within the first preset time period. In other words, the cooling capacity of the chiller air conditioning system 100 cannot be increased to the required cooling load in time within the first preset time period, and the chiller 101 needs to be turned on.

[0204] If the load change rate does not reach the upper limit of the load change rate of the chiller 101 to be turned on or off, it indirectly indicates that there is a slight load fluctuation within the first preset time period (the fluctuation may also be caused by sensor measurement error). In this case, even if the corresponding chiller 101 is not turned on or off, the water temperature can be adjusted to the set value within the first preset time period.

[0205] In this way, through the above steps 161 to 166, the frequent start and stop of the chiller 101 can be reduced, ensuring system stability. Here, the first preset time length can be a time set for periodically obtaining the cooling load of the chiller air conditioning system 100. For example, the first preset time length T1 is 5 minutes.

[0206] In some embodiments, the load change rate ROC is related to the required cooling load of the chiller air conditioning system 100, the cooling load of the chiller air conditioning system 100, and the first preset time T1. For example, the load change rate ROC satisfies the formula (301) with the required cooling load of the chiller air conditioning system 100, the cooling load of the chiller air conditioning system 100, and the first preset time T1. ROC=(Q d -Q f ) / T1 (301)

[0207] Here, Q f is the cooling load demand of the chiller air conditioning system 100, Q d is the cooling load of the chiller air-conditioning system 100, and T1 is the first preset time.

[0208] In some embodiments, it is assumed that the appropriate start-stop time interval of the chiller 101 in the chiller air-conditioning system 100 is the second preset time length T2. For example, the second preset time length T2 is 30 minutes.

[0209] If a chiller 101 needs to be started, the controller 5 can obtain the rated cooling load Q of the chiller 101. ch The load change rate ROC1 of the chiller 101 to be started can be calculated according to formula (302). ROC1 = Q ch / T2 (302)

[0210] When the load change rate ROC reaches the upper limit value ROC1 of the load change rate of the chiller 101 to be started (ie, ROC≥ROC1), the corresponding chiller 101 in the chiller air-conditioning system 100 is started.

[0211] It should be noted that only one chiller 101 is started at a time. Afterwards, the controller 5 returns to step 11 until the load change rate ROC is less than the upper limit value ROC1 of the load change rate of the chiller 101 to be started (ROC<the upper limit value of ROC1).

[0212] If a chiller 101 needs to be shut down, the controller 5 can obtain the rated cooling load Q of the chiller 101. ch .

[0213] The upper limit value ROC2 of the load change rate of the chiller 101 to be shut down can be calculated according to formula (303). ROC2 = Q ch / T2 (303)

[0214] When the load change rate ROC reaches the upper limit value ROC2 of the load change rate of the chiller 101 to be shut down (ROC≧ROC2), the corresponding chiller 101 in the chiller air-conditioning system 100 is shut down.

[0215] It should be noted that only one chiller 101 is shut down each time. Afterwards, the controller 5 returns to step 11 until the load change rate ROC is less than the upper limit value ROC2 of the load change rate of the chiller 101 to be shut down (ROC<ROC2).

[0216] For example, in the case where the chiller air-conditioning system 100 includes a 200-ton chiller 101 and a 150-ton chiller 101, if the controller 5 calculates that the energy efficiency of turning on two chillers 101 is greater than the energy efficiency of turning on one 200-ton chiller 101, then the chiller air-conditioning system 100 needs to operate under the condition of turning on two chillers 101.

[0217] If a 200-ton chiller 101 is currently running, it is determined that another 150-ton chiller 101 needs to be started. The controller 5 determines the rated cooling load Q of the 150-ton chiller 101 to be started. ch The load change rate ROC1 of the chiller 101 to be started is calculated using formula (302). If the load change rate ROC is greater than or equal to the upper limit value ROC1 of the load change rate of the chiller 101 to be started, the controller 5 determines to start the 150-ton chiller 101; otherwise, the controller keeps the current 200-ton chiller 101 running.

[0218] In the case where the chiller air-conditioning system 100 includes a 200-ton chiller and a 150-ton chiller 101, if the controller 5 calculates that the energy efficiency of starting one 200-ton chiller 101 is greater than the energy efficiency of starting two chillers 101, then the chiller air-conditioning system 101 needs to operate under the condition of starting one 150-ton chiller 101.

[0219] If two chillers 101 are currently in operation, it is determined that the other chiller 101 with a capacity of 150 refrigeration tons needs to be shut down.

[0220] The controller 5 is based on the rated cooling load Q of the 150-ton chiller 101 to be shut down. ch , calculate the load change rate ROC2 of the 150-ton chiller 101 to be shut down using formula (303).

[0221] If the load change rate ROC is greater than or equal to the upper limit value ROC2 of the load change rate of the chiller 101 to be shut down (ROC≥ROC2), the controller 5 determines to shut down the 150-ton chiller 101, otherwise, the two chillers 101 currently in operation are kept running.

[0222] It should be noted that when shutting down the corresponding chiller 101 , the chiller 101 with the longest running time in the chiller air-conditioning system 100 may be shut down first.

[0223] It should be noted that the steps executed by the controller 5 provided in some embodiments of the present disclosure can maintain high energy efficiency operation of the chiller air-conditioning system 100, and can also timely adjust the load of the chiller air-conditioning system 100 through the size of the load change rate ROC to achieve energy saving.

[0224] The following uses a chiller air conditioning system 100 consisting of a 300-ton chiller and a 250-ton chiller as an example to verify the steps performed by the controller 5 provided in some embodiments of the present disclosure.

[0225] Figure 11 is a statistical diagram of cooling load requirements at sample points of a chiller air conditioning system according to some embodiments. Figure 12 is a statistical diagram of chilled water supply temperature at sample points of a chiller air conditioning system according to some embodiments.

[0226] As shown in Figures 11 and 12, the horizontal axis represents the 559 sample points collected. Figure 11 shows the required cooling load Q of the 559 sample points. f Figure 12 shows the chilled water supply temperature Te at 559 sample points.

[0227] Figure 13 is a statistical graph showing the cooling water return temperature at sample points of a chiller air conditioning system according to some embodiments. Figure 14 is a statistical graph showing the control console count at sample points of a chiller air conditioning system according to some embodiments. Figure 15 is a statistical graph showing the predicted energy efficiency ratio at sample points of a chiller air conditioning system according to some embodiments.

[0228] As shown in Figures 13 to 15, the horizontal axis represents the 559 sample points collected. Figure 13 shows the cooling water return temperature Tc of the 559 sample points. Figure 14 shows the control console number of the 559 sample points. Figure 15 shows the predicted energy efficiency ratio COP of the 559 sample points. pre 14 and 15 , the chiller air conditioning system 100 is controlled by the steps executed by the controller 5 , and the control is efficient and accurate, and the chiller air conditioning system 100 has high stability.

[0229] The sequence numbers of the steps in some embodiments of the present disclosure are only for the convenience of describing some embodiments of the present disclosure and should not be understood as limiting the order of the steps. The order of execution of the steps can be determined according to actual needs and is not limited to the order of the steps in some embodiments of the present disclosure.

[0230] Some embodiments of the present disclosure further provide a control method for a chiller air conditioning system, which has a similar structure to the chiller air conditioning system 100. For example, the chiller air conditioning system includes multiple chillers 101 and a controller 5, and the method can be executed by the controller 5.

[0231] The method includes: calculating an average load rate of each of the plurality of chillers under a plurality of working conditions; the plurality of working conditions are different from each other, and the number of times the plurality of chillers are turned on is different under the plurality of working conditions; calculating an evaporation temperature and a condensation temperature of each chiller under the plurality of working conditions; calculating a first weight corresponding to each chiller under the plurality of working conditions based on the evaporation temperature and the condensation temperature of each chiller; the first weight is related to the temperature difference between the evaporation temperature and the condensation temperature; calculating a first weight corresponding to each chiller under the plurality of working conditions based on the evaporation temperature and the condensation temperature of each chiller; the first weight is related to the temperature difference between the evaporation temperature and the condensation temperature; calculating a first weight according to a preset performance model of the chiller and the temperature difference between the plurality of chillers under the plurality of working conditions. The evaporating temperature and condensing temperature of the chiller are used to calculate the predicted energy efficiency ratio of each chiller under the multiple operating conditions; the performance model characterizes the relationship between the performance coefficient, the average cooling load rate and the first weight; there is a preset relationship between the predicted energy efficiency ratio and the performance coefficient, the evaporating temperature and the condensing temperature; based on the predicted energy efficiency ratio of each chiller under the multiple operating conditions, the operating status of the multiple chillers is determined; the operating status of the chiller refers to whether the chiller is turned on or off; based on the determined operating status of the multiple chillers, the operation of the multiple chillers is controlled.

[0232] In some embodiments, the method further includes: after determining the operating status of the multiple chillers, calculating the load change rate of the cooling load of the chiller air-conditioning system at the previous moment relative to the required cooling load; if the load change rate reaches the upper limit value of the load change rate of the chiller to be turned on or off, controlling the chiller air-conditioning system to operate under the determined operating status; if the load change rate is less than the upper limit value of the load change rate of the chiller to be turned on or off, controlling the chiller air-conditioning system to continue operating under the current operating status.

[0233] In some embodiments, the method further includes: if the load change rate reaches the upper limit value of the load change rate of the chiller to be turned on, controlling the chiller to be turned on; if the load change rate reaches the upper limit value of the load change rate of the chiller to be turned off, controlling the chiller to be turned off to turn off; the chiller to be turned off is the chiller with the longest running time among the running chillers.

[0234] In some embodiments, the method further includes: calculating the average cooling load rate of each chiller under the multiple operating conditions based on the required cooling load of the chiller air-conditioning system, the number of chillers turned on in the chiller air-conditioning system, and the rated cooling loads of the multiple chillers.

[0235] In some embodiments, the method further includes: obtaining the chilled water supply temperature, the cooling water return temperature, the cooling water supply and return temperature difference corresponding to the chiller when operating at rated load, the evaporator heat exchange temperature difference corresponding to the chiller when operating at rated load, the condenser heat exchange temperature difference corresponding to the chiller when operating at rated load, and the chilled water supply and return temperature difference corresponding to the chiller when operating at rated load; calculating the evaporation temperature of each chiller under the multiple operating conditions according to a preset first relationship; the first relationship represents the relationship between the evaporation temperature and the average cooling load rate, the chilled water supply temperature, the cooling water supply and return temperature difference corresponding to the chiller when operating at rated load, and the condenser heat exchange temperature difference corresponding to the chiller when operating at rated load; calculating the condensing temperature of each chiller under the multiple operating conditions according to a preset second relationship; the second relationship represents the relationship between the condensing temperature and the average cooling load rate, the cooling water return temperature, the chilled water supply and return temperature difference corresponding to the chiller when operating at rated load, and the evaporator heat exchange temperature difference corresponding to the chiller when operating at rated load.

[0236] In some embodiments, the method further includes: calculating the first weight corresponding to each chiller based on the maximum temperature difference between the condensing temperature and the evaporating temperature of the chiller, the minimum temperature difference between the condensing temperature and the evaporating temperature of the chiller, and the calculated evaporating temperature and condensing temperature.

[0237] In some embodiments, the method further includes: collecting operating data of the chiller; the operating data includes the evaporation temperature, condensing temperature, and operating load of each single-head chiller in the chiller; determining the performance model of each single-head chiller based on the collected evaporation temperature, condensing temperature, operating load, and the rated cooling capacity and energy efficiency ratio of each single-head chiller; determining the performance model of the multi-head chiller based on the determined performance model of each single-head chiller; the performance model of the chiller includes at least one of the performance model of the single-head chiller or the performance model of the multi-head chiller.

[0238] In some embodiments, the method further includes: calculating the coefficient of performance of the single-head chiller based on the collected evaporation temperature, condensation temperature, and energy efficiency ratio; and fitting and determining a relationship equation for the coefficient of performance of the single-head chiller based on the coefficient of performance of the single-head chiller, a second weight, and a load rate. Here, the relationship equation for the coefficient of performance of the single-head chiller is a performance model of the single-head chiller, and the second weight is related to the collected evaporation temperature, the collected condensation temperature, and the temperature difference between the condensing temperature and the evaporation temperature of the single-head chiller.

[0239] In some embodiments, the method further includes: calculating the load rate based on the operating load and rated cooling capacity of the single-head chiller and the current cooling capacity of the chiller.

[0240] In some embodiments, the method further includes: calculating the predicted energy efficiency ratio of each single-head chiller based on the determined performance model of each single-head chiller, the collected evaporation temperature and condensation temperature; determining the electric power of the chiller based on the predicted energy efficiency ratio and cooling capacity of each single-head chiller; the cooling capacity of each single-head chiller is related to the operating load of the single-head chiller and the current cooling capacity of the chiller; and determining the predicted energy efficiency ratio of the multi-head chiller based on the electric power and the current cooling capacity of the chiller.

[0241] In some embodiments, the method further includes: deleting abnormal values ​​in the collected operating data.

[0242] In some embodiments, the deletion of abnormal values ​​in the collected operating data includes: calculating the current cooling capacity of the chiller based on the chilled water return temperature, the chilled water supply temperature, the chilled water flow rate and the specific heat capacity of water; calculating the current heat rejection of the chiller based on the cooling water outlet temperature, the cooling water inlet temperature, the cooling water flow rate and the specific heat capacity of water; calculating the energy balance coefficient based on the current cooling capacity of the chiller, the current heat rejection of the chiller and the operating power of each single-head chiller; if the energy balance coefficient is greater than a preset value, determining that the collected operating data is an abnormal value; and deleting the operating data determined to be an abnormal value.

[0243] Those skilled in the art will understand that the scope of the present invention is not limited to the above specific embodiments, and that certain elements of the embodiments may be modified and replaced without departing from the spirit of the present application. The scope of the present application is limited by the appended claims.

Claims

1. A chiller air-conditioning system, comprising: Multiple chillers, wherein the multiple chillers share a water circuit, and the refrigerant circuits of the multiple chillers are independent of each other. Each chiller of the multiple chillers includes: At least one compressor, configured to compress the refrigerant so that the low-pressure refrigerant is compressed to form a high-pressure refrigerant; A condenser, configured to condense the gaseous refrigerant into a liquid refrigerant and exchange heat with the cooling water; A throttling element, configured to control the flow rate and pressure of the refrigerant flowing through the throttling element; and An evaporator, configured to evaporate the liquid refrigerant into a gaseous refrigerant and exchange heat with the chilled water; the compressor, the condenser, the throttling element, and the evaporator are connected in sequence to form a refrigerant cycle; and A controller, the controller being configured to: Establish a performance model of the chiller; the performance model of the chiller is related to the operating data of the chiller; Calculate the target parameters of each chiller among the multiple chillers under multiple operating conditions; the multiple operating conditions are different from each other, and the number of the multiple chillers turned on is different under the multiple operating conditions; Calculate the predicted energy efficiency ratio of each chiller according to at least one of the performance model of the chiller and the target parameters of each chiller; Determine the operating state of the multiple chillers according to the predicted energy efficiency ratio of each chiller; the operating state of the chiller refers to whether the chiller is turned on or off; and Control the operation of the multiple chillers according to the determined operating state of the multiple chillers.

2. The chiller air conditioning system according to claim 1, wherein, The target parameters include the average load rate, the evaporation temperature, the condensation temperature, and a first weight value. The controller is configured to: Calculate the average load rate of each chiller under the multiple operating conditions; Calculate the evaporation temperature and the condensation temperature of each chiller under the multiple operating conditions; Calculate the corresponding first weight value of each chiller under the multiple operating conditions according to the evaporation temperature and the condensation temperature of each chiller; the first weight value is related to the temperature difference between the evaporation temperature and the condensation temperature.

3. The chiller air conditioning system according to claim 2, wherein, After calculating the first weight value, the controller is configured to: Calculate the predicted energy efficiency ratio of each chiller under the multiple operating conditions according to the performance model of the chiller and the evaporation temperature and the condensation temperature of each chiller under the multiple operating conditions; Wherein, the performance model characterizes the relationship between the performance coefficient and the average load rate and the first weight value; there is a preset relationship between the predicted energy efficiency ratio and the performance coefficient, the evaporation temperature, and the condensation temperature; the target parameters include the evaporation temperature and the condensation temperature of each chiller under the multiple operating conditions.

4. The chiller air-conditioning system according to claim 2, wherein, The controller is configured to: Obtain the chilled water supply temperature, the cooling water return temperature, the cooling water supply and return temperature difference corresponding to the chiller operating at the rated load, the evaporator heat transfer temperature difference corresponding to the chiller operating at the rated load, the condenser heat transfer temperature difference corresponding to the chiller operating at the rated load, and the chilled water supply and return temperature difference corresponding to the chiller operating at the rated load; Calculate the evaporation temperature of each chiller under the working condition according to a preset first relationship; the first relationship characterizes the relationship between the evaporation temperature, the average cooling load rate, the chilled water supply temperature, the cooling water supply and return temperature difference corresponding to the chiller operating at the rated load, and the condenser heat transfer temperature difference corresponding to the chiller operating at the rated load; Calculate the condensation temperature of each chiller under the working condition according to a preset second relationship; the second relationship characterizes the relationship between the condensation temperature, the average cooling load rate, the cooling water return temperature, the chilled water supply and return temperature difference corresponding to the chiller operating at the rated load, and the evaporator heat transfer temperature difference corresponding to the chiller operating at the rated load.

5. The chiller air-conditioning system according to claim 3, wherein, The controller is configured to: Calculate the first weight value corresponding to each chiller according to the maximum temperature difference between the condensation temperature and the evaporation temperature of the chiller, the minimum temperature difference between the condensation temperature and the evaporation temperature of the chiller, the calculated evaporation temperature and condensation temperature.

6. The chiller air conditioning system according to any one of claims 1 to 5, wherein, The chiller includes one of a single-head chiller and a multi-head chiller. The single-head chiller includes one compressor, and the multi-head chiller includes multiple compressors. The multi-head chiller is composed of multiple single-head chillers. The controller is further configured to: Collect the operation data of the chiller; the operation data includes the evaporation temperature, condensation temperature, and operation load of each single-head chiller in the chiller; Determine the performance model of each single-head chiller according to the collected evaporation temperature, condensation temperature, operation load, the rated cooling capacity and energy efficiency ratio of each single-head chiller; Determine the performance model of the multi-head chiller according to the determined performance model of each single-head chiller; the performance model of the chiller includes at least one of the performance model of the single-head chiller or the performance model of the multi-head chiller.

7. The chiller air-conditioning system according to claim 6, wherein, The controller is configured to: Calculate the coefficient of performance of the single-head chiller according to the collected evaporation temperature, condensation temperature and energy efficiency ratio; Fit and determine the relational expression of the coefficient of performance of the single-head chiller according to the coefficient of performance of the single-head chiller, the second weight value and the load rate; Wherein, the relational expression of the coefficient of performance of the single-head chiller is the performance model of the single-head chiller, and the second weight value is related to the collected evaporation temperature, the collected condensation temperature, and the temperature difference between the condensation temperature and the evaporation temperature of the single-head chiller.

8. The chiller air conditioning system according to claim 7, wherein, The load rate is related to the operating load and rated cooling capacity of the single-head chiller, and the current cooling capacity of the chiller; the current cooling capacity is related to the collected return water temperature of the chilled water, the collected supply water temperature of the chilled water, the collected chilled water flow rate, and the specific heat capacity of water.

9. The chiller air conditioning system according to claim 7, wherein, The controller is configured to: Calculate the predicted energy efficiency ratio of each single-head chiller according to the determined performance model of each single-head chiller, the collected evaporation temperature and condensation temperature; Determine the electric power of the chiller according to the predicted energy efficiency ratio and cooling capacity of each single-head chiller; the cooling capacity of each single-head chiller is related to the operating load of the single-head chiller and the current cooling capacity of the chiller; Determine the predicted energy efficiency ratio of the multi-head chiller according to the electric power and the current cooling capacity of the chiller.

10. The chiller air conditioning system according to claim 6, wherein, The collected operating data further includes the supply water temperature of the chilled water, the return water temperature of the chilled water, the chilled water flow rate, the inlet water temperature of the cooling water, the outlet water temperature of the cooling water, the cooling water flow rate, and the operating power of each single-head chiller in the chiller; the controller is further configured to: Calculate the current cooling capacity of the chiller according to the return water temperature of the chilled water, the supply water temperature of the chilled water, the chilled water flow rate, and the specific heat capacity of water; Calculate the current heat rejection of the chiller according to the outlet water temperature of the cooling water, the inlet water temperature of the cooling water, the cooling water flow rate, and the specific heat capacity of water; Calculate the energy balance coefficient according to the current cooling capacity of the chiller, the current heat rejection of the chiller, and the operating power of each single-head chiller; If the energy balance coefficient is greater than the preset value, determine that the collected operating data is an outlier; Delete the operating data determined to be an outlier.

11. The chiller air conditioning system according to any one of claims 2 to 10, wherein, The controller is configured to: Calculate the average cold load rate of each chiller under multiple working conditions according to the required cooling load of the chiller air-conditioning system, the number of chillers turned on in the chiller air-conditioning system, and the rated cooling load of the multiple chillers.

12. The chiller air conditioning system according to any one of claims 1 to 11, wherein, The controller is further configured to: After determining the operating state of the multiple chillers, calculate the load change rate of the cold load of the chiller air-conditioning system at the previous moment relative to the required cooling load; If the load change rate reaches the upper limit value of the load change rate of the chiller to be turned on or off, control the chiller air-conditioning system to operate in the determined operating state; If the load change rate is less than the upper limit value of the load change rate of the chiller to be turned on or off, control the chiller air-conditioning system to continue operating in the current operating state.

13. The chiller air conditioning system according to claim 12, wherein, The controller is further configured to: If the load change rate reaches the upper limit value of the load change rate of the chiller to be turned on, control the chiller to be turned on; If the load change rate reaches the upper limit value of the load change rate of the chiller to be turned off, control the chiller to be turned off; the chiller to be turned off is the chiller with the longest operating time among the operating chillers.

14. The chiller air-conditioning system according to claim 13, wherein, The load change rate is related to the required cooling load of the chiller air conditioning system, the cooling load of the chiller air conditioning system, and a first preset time period; The upper limit value of the load change rate of the chiller to be started is the ratio of the rated cooling load of the chiller to be started to a second preset time period; The upper limit value of the load change rate of the chiller to be shut down is the ratio of the rated cooling load of the chiller to be shut down to the second preset time period.

15. A control method for a chiller air conditioning system, the chiller air conditioning system comprising: A plurality of chillers, the plurality of chillers sharing a water circuit, and the refrigerant circuits of the plurality of chillers being independent of each other. Each chiller of the plurality of chillers includes: At least one compressor, configured to compress the refrigerant so that the low-pressure refrigerant is compressed to form a high-pressure refrigerant; A condenser, configured to condense the gaseous refrigerant into a liquid refrigerant and exchange heat with the cooling water; A throttle member, configured to control the flow rate and pressure of the refrigerant flowing through the throttle member; and An evaporator, configured to evaporate the liquid refrigerant into a gaseous refrigerant and exchange heat with the chilled water; the compressor, the condenser, the throttle member, and the evaporator are connected in sequence to form a refrigerant cycle; and A controller, configured to control the operation of the plurality of chillers; The method includes: Calculating the average load rate of each chiller in the plurality of chillers under a plurality of operating conditions; the plurality of operating conditions are different from each other, and the number of the plurality of chillers started is different under the plurality of operating conditions; Calculating the evaporation temperature and the condensation temperature of each chiller under the plurality of operating conditions; According to the evaporation temperature and the condensation temperature of each chiller, calculating a first weight value corresponding to each chiller under the plurality of operating conditions; the first weight value is related to the temperature difference between the evaporation temperature and the condensation temperature; According to the preset performance model of the chiller and the evaporation temperature and the condensation temperature of each chiller under the plurality of operating conditions, calculating the predicted energy efficiency ratio of each chiller under the plurality of operating conditions; the performance model characterizes the relationship between the performance coefficient, the average cooling load rate, and the first weight value; there is a preset relationship between the predicted energy efficiency ratio, the performance coefficient, the evaporation temperature, and the condensation temperature; According to the predicted energy efficiency ratio of each chiller under the plurality of operating conditions, determining the operating state of the plurality of chillers; the operating state of the chiller refers to whether the chiller is started or shut down; and Controlling the operation of the plurality of chillers according to the determined operating state of the plurality of chillers.

16. The control method for a chiller air conditioning system according to claim 15, controlling the operation of the plurality of chillers according to the determined operating state of the plurality of chillers, includes: After determining the operating state of the plurality of chillers, calculating the load change rate of the cooling load of the chiller air conditioning system at the previous moment relative to the required cooling load; If the load change rate reaches the upper limit value of the load change rate of the chiller to be started or stopped, control the chiller air-conditioning system to operate in the determined operating state; If the load change rate is less than the upper limit value of the load change rate of the chiller to be started or stopped, control the chiller air-conditioning system to continue operating in the current operating state.

17. The control method of the chiller air-conditioning system according to claim 16, wherein, If the load change rate reaches the upper limit value of the load change rate of the chiller to be started or stopped, controlling the chiller air-conditioning system to operate in the determined operating state includes: If the load change rate reaches the upper limit value of the load change rate of the chiller to be started, control the chiller to be started to start; If the load change rate reaches the upper limit value of the load change rate of the chiller to be stopped, control the chiller to be stopped to stop; the chiller to be stopped is the chiller with the longest operating time among the operating chillers.

18. The control method of the chiller air-conditioning system according to any one of claims 15 to 17, wherein, The calculating the average load rate of each chiller among the multiple chillers under multiple working conditions includes: According to the required cooling load of the chiller air-conditioning system, the number of chillers started in the chiller air-conditioning system, and the rated cooling load of the multiple chillers, calculate the average cooling load rate of each chiller under the multiple working conditions.

19. The control method of the chiller air conditioning system according to any one of claims 15 to 18, wherein, The chiller includes one of a single-head chiller and a multi-head chiller. The single-head chiller includes one compressor, and the multi-head chiller includes multiple compressors. The multi-head chiller is composed of multiple single-head chillers. The method further includes: Collect the operating data of the chiller; the operating data includes the evaporation temperature, condensation temperature, and operating load of each single-head chiller in the chiller. According to the collected evaporation temperature, condensation temperature, operating load, and the rated cooling capacity and energy efficiency ratio of each single-head chiller, determine the performance model of each single-head chiller. According to the determined performance model of each single-head chiller, determine the performance model of the multi-head chiller; the performance model of the chiller includes at least one of the performance model of the single-head chiller or the performance model of the multi-head chiller.

20. The control method of the chiller air-conditioning system according to claim 19, determining the performance model of each single-head chiller according to the collected evaporation temperature, condensation temperature, operating load, and the rated cooling capacity and energy efficiency ratio of each single-head chiller includes: According to the collected evaporation temperature, condensation temperature, and energy efficiency ratio, calculate the performance coefficient of the single-head chiller. According to the performance coefficient, second weight, and load rate of the single-head chiller, fit and determine the relational expression of the performance coefficient of the single-head chiller. Wherein, the relational expression of the performance coefficient of the single-head chiller is the performance model of the single-head chiller, and the second weight is related to the collected evaporation temperature, the collected condensation temperature, and the temperature difference between the condensation temperature and evaporation temperature of the single-head chiller.

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