Centrifugal water chilling unit, control method and device for centrifugal water chilling unit and computer readable storage medium

Abstract

The invention relates to the technical field of water chilling units, and discloses a centrifugal water chilling unit which comprises a centrifugal compressor, a condenser and an evaporator which are sequentially connected through a pipeline, and further comprises a bypass pipeline, an air inlet pipe, an air outlet pipe and an air outlet pipe, and the opening degree adjusting device is arranged on the bypass pipeline and is configured to controllably connect or disconnect the bypass pipeline. The bypass pipeline is additionally arranged for the centrifugal water chilling unit, when the unit has the load shedding requirement, the bypass pipeline is conducted through the opening adjusting device, the exhaust pressure of the compressor can be reduced, the suction pressure of the compressor can be improved, the pressure ratio of the compressor is reduced, and the purpose that the load of the unit continues to be reduced is achieved. After the load range is widened, the corresponding IPLV is also improved, and the whole machine achieves the purpose of energy conservation. The invention further discloses a control method and device for the centrifugal water chilling unit and a computer readable storage medium.

Description

Technical Field

[0001] The present application relates to the technical field of chillers, for example, to a centrifugal chiller, a control method and device therefor, and a computer-readable storage medium. Background Art

[0002] Currently, under the general trend of low-carbon environmental protection, reducing carbon emissions and improving the energy efficiency ratio have become the most important tasks for current heating, ventilation, and air conditioning (HVAC) equipment. Among HVAC equipment, large chillers represented by centrifuges have led the market growth trend in recent years.

[0003] Compared with magnetic levitation centrifugal chillers and conventional variable-frequency centrifugal chillers, the COP (Coefficient Of Performance, coefficient of heating energy efficiency) of conventional fixed-frequency centrifugal chillers is higher, but the IPLV (Integrated PartLoad Value, integrated part-load performance coefficient) is lower, the unloading capacity of the whole machine is poor, and the partial load operation range is narrower.

[0004] Existing technologies usually limit the compressor suction volume by adjusting the opening of the IGV (Intake Guide Vane). The less the suction volume, the smaller the refrigeration capacity. The opening of the IGV is usually limited to 10% to 100%. After the IGV is limited to the minimum opening of 10%, the compressor load is about 50%, and the corresponding refrigeration capacity is about 50%. Therefore, for conventional fixed-frequency centrifugal chillers, by simply adjusting the IGV, the refrigeration load can only be unloaded to 50% at the lowest, which is difficult to meet the energy-saving requirements.

[0005] It should be noted that the information disclosed in the above background art section is only used to enhance the understanding of the background of the present application, and thus may include information that does not constitute the prior art known to those of ordinary skill in the art. Summary of the Invention

[0006] To have a basic understanding of some aspects of the disclosed embodiments, a simple summary is given below. This summary is not a general review, nor is it intended to identify key / important constituent elements or delineate the protection scope of these embodiments. Instead, it serves as a preface to the subsequent detailed description.

[0007] The embodiments of the present disclosure provide a centrifugal chiller, a control method and device therefor, and a computer-readable storage medium, so as to broaden the load unloading range of the centrifugal water chiller, thereby improving the performance of the whole machine and meeting the energy-saving requirements.

[0008] In some embodiments, the centrifugal chiller includes a centrifugal compressor, a condenser, and an evaporator connected in sequence through pipelines, and further includes: a bypass pipeline, the inlet of the bypass pipeline is connected to the condenser, and the outlet of the bypass pipeline is connected to the evaporator; an opening adjustment device, which is arranged on the bypass pipeline and is configured to controllably conduct or cut off the bypass pipeline.

[0009] Optionally, the opening adjustment device is configured to conduct the bypass pipeline when the current outlet water temperature is less than the target temperature and the unit load is less than or equal to the set threshold.

[0010] Optionally, the opening adjustment device is further configured to adjust the opening degree of the bypass pipeline according to the current outlet water temperature of the unit when the difference between the target temperature and the shutdown temperature difference is less than the current outlet water temperature and the current outlet water temperature is less than the target temperature.

[0011] In some embodiments, a centrifugal chiller includes a centrifugal compressor, a condenser, and an evaporator connected in sequence through pipelines; and a bypass pipeline, the inlet of the bypass pipeline is connected to the condenser, and the outlet of the bypass pipeline is connected to the evaporator; the control method for the centrifugal chiller includes:

[0012] including detecting the current outlet water temperature of the chiller; when the current outlet water temperature is less than the target temperature, controlling the chiller to start unloading and reducing the IGV opening; obtaining the unit load at the current IGV opening; when the unit load is less than or equal to the set threshold, controlling the IGV opening to remain at the lowest level and controlling the bypass pipeline to conduct.

[0013] Optionally, obtaining the unit load at the current IGV opening includes: obtaining the current current of the centrifugal compressor; calculating the unit load according to the ratio of the current current to the maximum current and the current IGV opening.

[0014] Optionally, calculating the unit load according to the ratio of the current current to the maximum current and the current IGV opening includes:

[0015] Calculating Z = a1X 3 +a2X 2 Y + a3XY 2 +a4XY + a5X 2 +a6Y 2 ;

[0016] where Z is the unit load, X is the IGV opening ratio, Y is the ratio of the current current to the maximum current, and a1 to a6 are fitting coefficients, 0 > a1 > a5 > a3, 0 < a2 < a6 < a4.

[0017] Optionally, after controlling the bypass pipeline to conduct, it further includes:

[0018] Detect the current chilled water outlet temperature of the chiller unit;

[0019] When the difference between the target temperature and the shutdown temperature difference is less than the current chilled water outlet temperature and the current chilled water outlet temperature is less than the target temperature, adjust the opening degree of the bypass pipeline according to the current chilled water outlet temperature of the unit.

[0020] Optionally, adjusting the opening degree of the bypass pipeline according to the current chilled water outlet temperature of the unit includes:

[0021] When Ts - △T < t < Ts - △T + m, adjust the current opening degree of the bypass pipeline to W = W + 10%;

[0022] When Ts - △T + m < t < Ts, adjust the bypass pipeline to maintain the current opening degree W;

[0023] Wherein, Ts is the target temperature, △T is the shutdown temperature difference value of the chiller unit, m is the adjustment value, t is the current chilled water outlet temperature, and W is the current opening degree of the bypass pipeline.

[0024] Optionally, after adjusting the opening degree of the bypass pipeline according to the current chilled water outlet temperature of the chiller unit, it further includes:

[0025] Calculate the unit load according to the current opening degree of the bypass pipeline;

[0026] When the unit load is greater than the set threshold and the current chilled water outlet temperature is greater than the target temperature, control the bypass pipeline to be cut off.

[0027] Optionally, calculating the unit load according to the current opening degree of the bypass pipeline includes:

[0028] Obtain the current current of the centrifugal compressor;

[0029] Calculate the unit load according to the ratio of the current current to the maximum current and the current opening degree of the bypass pipeline.

[0030] Optionally, calculating the unit load according to the ratio of the current current to the maximum current and the current opening degree of the bypass pipeline includes:

[0031] Calculate Z = b1W 3 +b2W 2 Y + b3WY + b4W 2 ;

[0032] Wherein, Z is the unit load, W is the current opening degree ratio of the bypass pipeline, Y is the ratio of the current current to the maximum current, b1 to b4 are fitting coefficients, 0 > b2, 0 < b1 < b4 < b3.

[0033] In some embodiments, a centrifugal chiller includes a centrifugal compressor, a condenser, and an evaporator connected in sequence through pipelines; and a bypass pipeline, the inlet of the bypass pipeline is connected to the condenser, and the outlet of the bypass pipeline is connected to the evaporator; an opening adjustment device is provided on the bypass pipeline and is configured to controllably conduct or cut off the bypass pipeline; the control device for the centrifugal chiller includes: a temperature detection device configured to detect the current chilled water outlet temperature of the chiller; an IGV opening control device configured to control the chiller to start unloading and reduce the IGV opening when the current chilled water outlet temperature is lower than the target temperature; a unit load calculation device configured to obtain the unit load at the current IGV opening; a bypass pipeline opening control device configured to control the IGV opening to be kept at the lowest and control the bypass pipeline to conduct when the unit load is less than or equal to a set threshold.

[0034] In some embodiments, the control device for the air conditioner unit includes a processor and a memory storing program instructions, and is characterized in that the processor is configured to execute the control method for the centrifugal chiller as described above when running the program instructions.

[0035] In some embodiments, the computer-readable storage medium stores program instructions, and is characterized in that the program instructions, when running, are used to cause a computer to execute the control method for the centrifugal chiller as described above.

[0036] The centrifugal chiller, the control method and device therefor, and the computer-readable storage medium provided by the embodiments of the present disclosure can achieve the following technical effects:

[0037] By adding a bypass pipeline to the centrifugal chiller, when the unit has a load reduction requirement, the opening adjustment device is used to conduct the bypass pipeline. In this way, the high-pressure gas in the condenser enters the evaporator through the bypass pipeline, which can reduce the compressor discharge pressure, increase the compressor suction pressure, and further reduce the compressor pressure ratio, so as to achieve the purpose of further reducing the load of the unit. The load range can be widened from the original 50% to 100% to 10% to 100%. After the load range is widened, the corresponding IPLV is also increased, and the whole machine achieves the energy-saving purpose.

[0038] The above general description and the following description are only exemplary and explanatory, and are not used to limit the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] One or more embodiments are exemplarily illustrated by the corresponding drawings. These exemplary illustrations and the drawings do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings are shown as similar elements. The drawings do not constitute a proportional limitation, and among them:

[0040] Figure 1It is a structural block diagram of a centrifugal chiller provided by an embodiment of the present disclosure;

[0041] Figure 2 It is a schematic flowchart of a control method for a centrifugal chiller provided by an embodiment of the present disclosure;

[0042] Figure 3 It is a schematic flowchart of another control method for a centrifugal chiller provided by an embodiment of the present disclosure;

[0043] Figure 4 It is a schematic flowchart of another control method for a centrifugal chiller provided by an embodiment of the present disclosure;

[0044] Figure 5 It is a schematic flowchart of another control method for a centrifugal chiller provided by an embodiment of the present disclosure;

[0045] Figure 6 It is a schematic diagram of a control device for a centrifugal chiller provided by an embodiment of the present disclosure;

[0046] Figure 7 It is a schematic diagram of another control device for a centrifugal chiller provided by an embodiment of the present disclosure;

[0047] Figure 8 It is a structural block diagram of a centrifugal chiller provided by an embodiment of the present disclosure. Detailed implementation manners

[0048] In order to be able to understand the features and technical content of the embodiments of the present disclosure in more detail, the implementation of the embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. The attached drawings are for reference and illustration only, and are not used to limit the embodiments of the present disclosure. In the following technical description, for the sake of explanation, multiple details are provided to give a full understanding of the disclosed embodiments. However, one or more embodiments can still be implemented without these details. In other cases, well-known structures and devices can be shown in a simplified manner to simplify the drawings.

[0049] The terms "first", "second", etc. in the specification, claims and above-mentioned drawings of the embodiments of the present disclosure are used to distinguish similar objects, and do not have to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so as to implement the embodiments of the present disclosure described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusion.

[0050] Unless otherwise specified, the term "plurality" means two or more.

[0051] In the embodiments of the present disclosure, the character " / " indicates an "or" relationship between the front and rear objects. For example, A / B means: A or B.

[0052] The term "and / or" is an associative relationship describing an object, indicating that three relationships can exist. For example, A and / or B means: A or B, or, A and B, these three relationships.

[0053] The term "corresponding" can refer to an associative relationship or a binding relationship. A corresponding to B means that there is an associative relationship or a binding relationship between A and B.

[0054] Figure 1 It is a centrifugal chiller provided by the embodiments of the present disclosure, including a centrifugal compressor 11, a condenser 12, an evaporator 13, a bypass pipeline 21, and an opening adjustment device 22. Among them, the centrifugal compressor 11, the condenser 12, and the evaporator 13 are sequentially connected through pipelines to form a refrigeration cycle loop. The inlet of the bypass pipeline 21 is connected to the condenser 12, and the outlet is connected to the evaporator 13; the opening adjustment device 22 is arranged on the bypass pipeline 21 and is configured to controllably conduct or cut off the bypass pipeline 21.

[0055] Here, the bypass pipeline 21 is a pipeline connecting the evaporator 13 and the condenser 12, and an opening adjustment device 22 is connected to the pipeline for adjusting the opening degree of the pipeline conduction. The opening adjustment device 22 can be an electric valve, such as an electric ball valve, an electric butterfly valve, an electronic expansion valve, or a combination of a manual valve and an electric actuator, such as an electric actuator and a butterfly valve, a ball valve, a throttle valve, etc.

[0056] Optionally, it further includes a silencer 23, which is arranged on the bypass pipeline 21. The silencer 23 is arranged between the opening adjustment device 22 and the evaporator 13 and is used to reduce the airflow noise after the bypass pipeline 21 is conducted.

[0057] Optionally, a throttle orifice plate 14 is arranged on the pipeline between the condenser 12 and the evaporator 13. The throttle orifice plate 14 is used to regulate the flow rate, regulate the pressure, and stabilize the fluid in the pipeline.

[0058] Optionally, the opening adjustment device 22 is configured to conduct the bypass pipeline 21 when the current outlet water temperature is less than the target temperature and the unit load is less than or equal to the set threshold.

[0059] Thus, when the unit is operating normally, the bypass pipeline 21 is in a cut-off state. The low-temperature and low-pressure gaseous refrigerant is compressed into a high-temperature and high-pressure gaseous refrigerant by the centrifugal compressor 11 and then flows into the condenser 12, where it is condensed into a high-temperature and high-pressure liquid refrigerant. Then, through the throttling effect of the orifice plate 14, the pressure and temperature of the liquid refrigerant decrease, and it evaporates into a low-temperature and low-pressure gaseous refrigerant in the evaporator 13, completing the refrigeration cycle. When there is a load reduction requirement for the unit, the opening adjustment device 22 adjusts the opening according to the actual load reduction requirement, making the bypass pipeline 21 conductive. The high-pressure gas in the condenser 12 enters the evaporator 13, reducing the exhaust pressure and increasing the suction pressure, thereby reducing the compressor pressure ratio.

[0060] Optionally, it further includes a temperature sensor configured to obtain the outlet water temperature of the centrifugal chiller.

[0061] Optionally, it further includes a control device configured to control the opening adjustment device 22 to conduct or cut off the bypass pipeline 21.

[0062] Optionally, the control device is further configured to control the opening adjustment device 22 to adjust the conduction opening of the bypass pipeline 21 according to the outlet water temperature detected by the temperature sensor; the opening adjustment device 22 is further configured to, when the difference between the target temperature and the shutdown temperature difference is less than the current outlet water temperature and the current outlet water temperature is less than the target temperature, adjust the conduction opening of the bypass pipeline 21 according to the current outlet water temperature of the unit.

[0063] During the load unloading process, the difference between the target temperature and the current outlet water temperature cannot be greater than the shutdown temperature difference, otherwise the unit will directly shut down. Therefore, the further adjustment of the bypass pipeline 21 needs to be controlled in real time according to the current outlet water temperature.

[0064] Figure 2 is a control method for a centrifugal chiller provided by an embodiment of the present disclosure, used to control Figure 1 the centrifugal chiller shown. In the embodiment of the present disclosure, the control device of this chiller is used as the execution subject to illustrate the solution.

[0065] As Figure 2 shown, this control method for a centrifugal chiller includes:

[0066] Step S201, the control device detects the current outlet water temperature of the chiller.

[0067] Step S202, when the current outlet water temperature is less than the target temperature, the control device controls the chiller to start unloading and reduce the IGV opening.

[0068] Here, the control device detects the chilled water outlet temperature of the current chiller through a sensor, and then calculates the magnitude relationship between the current outlet temperature and the target temperature. By monitoring the outlet temperature of the chiller in real time and determining the magnitude relationship with the target temperature, the current operating state of the chiller can be determined, providing data support for subsequent control. If the current outlet temperature is greater than or equal to the target temperature, the unit operates at full load according to the normal loading requirement. If the current outlet temperature is less than the target temperature, it indicates that the unit has a load reduction requirement. At this time, the load is unloaded by reducing the IGV opening to adjust the refrigeration energy efficiency of the chiller, making the actual output temperature close to the target temperature, thereby improving the stability and energy efficiency of the system.

[0069] Step S203, the control device obtains the unit load at the current IGV opening.

[0070] Step S204, when the unit load is less than or equal to the set threshold, the control device controls the IGV opening to remain at the lowest level and controls the bypass pipeline to conduct.

[0071] The set threshold refers to the lowest value of the unit unloading load range that can be achieved by adjusting the IGV opening. When the unit load is less than or equal to the set threshold, it is necessary to rely on the conduction of the bypass pipeline to reduce the overall pressure ratio of the unit to achieve the purpose of further reducing the load of the unit.

[0072] When the unit load is less than or equal to the set threshold, the IGV opening has generally dropped to the lowest value. If the IGV opening does not drop to the lowest value under special working conditions, the IGV opening is controlled to remain at the lowest level and unchanged at this time. In the embodiment of the present disclosure, the set threshold is 50%, and the lowest value of the IGV opening is 10%.

[0073] Here, the control device controls the switch adjustment device to conduct the bypass pipeline, and at the same time, the unit load continues to unload according to the conducted bypass pipeline.

[0074] In this way, when the unit is operating normally, the bypass pipeline is in a cut-off state. The low-temperature and low-pressure gaseous refrigerant is compressed into a high-temperature and high-pressure gaseous refrigerant by the centrifugal compressor and then flows into the condenser, where it is condensed into a high-temperature and high-pressure liquid refrigerant. Then, after the throttling effect of the orifice plate, the pressure and temperature of the liquid refrigerant decreases, and it evaporates into a low-temperature and low-pressure gaseous refrigerant in the evaporator to complete the refrigeration cycle. When the unit has a load reduction demand, the load is first reduced by adjusting the IGV opening; when the unit load drops below the set threshold and the load still needs to be reduced, the bypass pipeline is opened through the opening adjustment device. In this way, the high-pressure gas in the condenser enters the evaporator through the bypass pipeline, which can reduce the compressor exhaust pressure, increase the compressor suction pressure, and then reduce the compressor pressure ratio, so as to achieve the purpose of continuing to reduce the load of the unit. The load range can be widened from the original 50% to 100% to 10% to 100%. After the load range is widened, the corresponding IPLV is also improved, and the whole machine achieves the purpose of energy saving.

[0075] If the chiller is a variable frequency centrifugal chiller, the step of adjusting the unit frequency is also included before reducing the IGV opening in step S202. After adjusting the compressor operating frequency according to the current outlet water temperature and the target temperature, the IGV opening is reduced and the remaining steps are performed. In this way, the minimum value of the load range can be reduced to less than 5%, further widening the load range, thereby improving the energy saving effect of the whole machine.

[0076] The scheme of adjusting the IGV opening is further described below in conjunction with specific embodiments.

[0077] Figure 3 The control method for a centrifugal chiller provided by the embodiment of the present disclosure is used to control Figure 1 In the disclosed embodiment, the control device of the centrifugal chiller is used as the execution body to illustrate the scheme.

[0078] like Figure 3 As shown, the control method for a centrifugal chiller comprises:

[0079] Step S301: The control device detects the current outlet water temperature of the chiller.

[0080] Step S302: When the current outlet water temperature is lower than the target temperature, the control device controls the chiller to start unloading and reduce the IGV opening. Then, the process proceeds to step S304.

[0081] Step S303: When the current outlet water temperature is greater than or equal to the target temperature, the control device controls the chiller to continue to operate and the bypass pipeline remains cut off.

[0082] Step S304: the control device obtains the current current of the centrifugal compressor.

[0083] For a centrifugal compressor, the steps to obtain the current current usually involve using a current sensor or a current measuring device. This device is connected to the electrical system of the centrifugal compressor to monitor and measure the current value passing through the compressor circuit in real time.

[0084] In step S305, the control device calculates the unit load according to the ratio of the current current to the maximum current and the current IGV opening degree.

[0085] Since the maximum currents of different models of compressors are different, the unit load is determined according to the current ratio here. When the unit starts to reduce the IGV opening degree, the unit current starts to decrease, and the unit load changes according to the IGV opening degree and the current. Therefore, through the ratio of the current current to the maximum current and the current IGV opening degree, the real-time working load state of the operating system can be obtained, providing data support for the energy efficiency optimization of the system.

[0086] In step S306, when the unit load is less than or equal to the set threshold, the IGV opening degree is controlled to remain the lowest, and the bypass pipeline is controlled to conduct. When the unit load is greater than the set threshold, return to step S301 to determine whether further unloading is required according to the current outlet water temperature. If further unloading is required, the IGV opening degree is further reduced in step S302.

[0087] Furthermore, calculating the unit load according to the ratio of the current current to the maximum current and the current IGV opening degree may include:

[0088] Determine the unit load corresponding to the ratio of the current current to the maximum current and the current IGV opening degree according to the corresponding relationship between the ratio of the current current to the maximum current, the IGV opening degree and the unit load.

[0089] Here, the corresponding relationship between the ratio of the current current to the maximum current, the IGV opening degree and the unit load can be stored in the database in the form of a one-to-one correspondence data table. After obtaining the ratio of the current current to the maximum current and the current IGV opening degree, by querying the database, the current unit load corresponding to the ratio of the current current to the maximum current and the current IGV opening degree can be obtained.

[0090] Alternatively, the corresponding relationship between the ratio of the current current to the maximum current, the IGV opening degree and the unit load can be sampled and fitted with a formula. After obtaining the ratio of the current current to the maximum current and the current IGV opening degree, substitute the ratio of the current current to the maximum current and the current IGV opening degree into the formula to obtain the current unit load corresponding to the ratio of the current current to the maximum current and the current IGV opening degree.

[0091] Specifically, the unit load is calculated in the following manner:

[0092] Calculate Z = a1X 3 + a2X 2 Y + a3XY 2 + a4XY + a5X 2 + a6Y 2 ;

[0093] Where Z is the unit load, X is the IGV opening ratio, Y is the ratio of the current current to the maximum current, and a1 to a6 are fitting coefficients, with 0 > a1 > a5 > a3 and 0 < a2 < a6 < a4.

[0094] As can be seen from the above formula, the relationship between the unit load and the change in the IGV opening is non - linear, and the relationship with the ratio of the current current to the maximum current is also non - linear. This means that as the IGV opening and the current current change, the change in the unit load is not linear but shows a certain curve characteristic. By adjusting the fitting coefficients, the calculation of the unit load can be further adjusted and optimized to better meet the control requirements, thereby achieving more efficient energy utilization and system performance.

[0095] Next, in combination with specific embodiments, further description will be made on how the opening adjustment device adjusts the opening of the bypass pipeline after the bypass pipeline is opened.

[0096] Figure 4 This is a control method provided by an embodiment of the present disclosure for a centrifugal chiller, used to control Figure 1 the centrifugal chiller shown. In the embodiment of the present disclosure, the control device of this chiller is used as the execution subject to illustrate the solution.

[0097] Step S401, the control device detects the current outlet water temperature of the chiller.

[0098] Step S402, when the current outlet water temperature is less than the target temperature, the control device controls the chiller to start unloading and reduces the IGV opening.

[0099] Step S403, the control device obtains the unit load at the current IGV opening.

[0100] Step S404, when the unit load is less than or equal to the set threshold, the control device controls the IGV opening to remain at the lowest level and controls the bypass pipeline to open.

[0101] Optionally, when controlling the bypass pipeline to open, the initial opening of the bypass pipeline is set to the current opening. Here, the initial opening of the bypass pipeline is set to 30%, that is, when the bypass pipeline is opened, the switch adjustment device adjusts the opening to 30%.

[0102] Step S405, the control device detects the current outlet water temperature of the chiller.

[0103] Step S406: When the difference between the target temperature and the shutdown temperature difference is less than the current outlet water temperature and the current outlet water temperature is less than the target temperature, adjust the opening degree of the bypass pipeline according to the current outlet water temperature of the unit.

[0104] Here, during the load unloading process, the difference between the target temperature and the current outlet water temperature cannot be greater than the shutdown temperature difference, otherwise the unit will directly shut down. Therefore, the further adjustment of the bypass pipeline needs to be controlled in real time according to the current outlet water temperature. That is, when the difference between the target temperature and the shutdown temperature difference is less than the current outlet water temperature and the current outlet water temperature is less than the target temperature, the opening degree of the bypass pipeline adjusts the real-time opening degree according to the outlet water temperature, and at the same time, the unit load adjusts according to the opening degree of the bypass pipeline. The shutdown temperature difference is usually 2°C to 3°C, and in the embodiments of the present disclosure, the shutdown temperature difference is set to 2°C.

[0105] Optionally, adjusting the opening degree of the bypass pipeline according to the current outlet water temperature of the unit includes:

[0106] Determine the opening degree of the bypass pipeline corresponding to the current outlet water temperature as the target opening degree according to the corresponding relationship between the temperature value range where the outlet water temperature of the unit is located and the opening degree of the bypass pipeline, and adjust the current opening degree to the target opening degree.

[0107] Here, the corresponding relationship between the temperature value range where the outlet water temperature is located and the opening degree of the bypass pipeline can be stored in the database in the form of a one-to-one correspondence data table. After obtaining the current outlet water temperature, determine the temperature value range it is in, and by querying the database, the opening degree of the bypass pipeline corresponding to the current outlet water temperature of the unit can be obtained. Specifically, the embodiments of the present disclosure implement the adjustment of the opening degree through steps S407 and S408.

[0108] Step S407: When Ts - △T < t < Ts - △T + m, adjust the current opening degree of the bypass pipeline to W = W + 10%. That is, increase the opening degree of the bypass pipeline by 10% based on the current opening degree.

[0109] Step S408: When Ts - △T + m < t < Ts, adjust the bypass pipeline to maintain the current opening degree W. Where Ts is the target temperature, △T is the shutdown temperature difference value of the chiller, m is the adjustment value, t is the current outlet water temperature, and W is the current opening degree of the bypass pipeline.

[0110] Among them, the value of m can be 0.5°C to 1.5°C. In the embodiments of the present disclosure, m is set to 1°C.

[0111] Optionally, the range of the opening degree of the bypass pipeline is 30% to 100%.

[0112] Step S409: Calculate the unit load according to the current opening degree of the bypass pipeline. After the bypass pipeline is opened, calculate the unit load according to the opening degree of the bypass pipeline.

[0113] Step S410: Control the bypass pipeline to be cut off when the unit load is greater than the set threshold and the current outlet water temperature is greater than the target temperature.

[0114] The set threshold refers to the minimum value of the unit unloading load range that can be achieved by adjusting the IGV opening. When the unit load is greater than the set threshold and the outlet water temperature is greater than the target temperature, the bypass pipeline can be controlled to be cut off, and the unit resumes normal operation.

[0115] Here, when the unit load is greater than the set threshold, further determine whether the current outlet water temperature is greater than the target temperature to determine whether there is a load unloading requirement. If the current outlet water temperature is greater than the target temperature, it indicates that the unit load has met the working condition requirements and there is no need to continue unloading. At this time, the bypass pipeline can be controlled to be cut off. If the unit load is less than the set threshold and / or the current outlet water temperature is less than or equal to the target temperature, it means that it is necessary to return to step S405 and continue to adjust the current opening degree of the bypass pipeline according to the current outlet water temperature.

[0116] In this way, when the outlet water temperature of the unit continues to drop, the opening degree of the bypass pipeline is adjusted according to the temperature value range where the outlet water temperature is located, so as to further unload the load.

[0117] In this way, through the control method for a chiller provided by the embodiment of the present disclosure, when the unit has a load reduction requirement, the load is first reduced by adjusting the IGV opening; when the unit load drops below the set threshold and further load reduction is still required, the bypass pipeline is opened through the opening adjustment device, and the actual load reduction requirement is determined according to the current outlet water temperature to continue adjusting the opening. In this way, the high-pressure gas in the condenser enters the evaporator through the bypass pipeline, which can reduce the compressor discharge pressure, increase the compressor suction pressure, and then reduce the compressor pressure ratio, so as to achieve the purpose of further reducing the unit load. The load range can be widened from the original 50% to 100% to 10% to 100%. After the load range is widened, the corresponding IPLV is also increased, and the whole machine achieves the purpose of energy saving.

[0118] Figure 5 It is a control method for a centrifugal chiller provided by the embodiment of the present disclosure, used to control Figure 1 the centrifugal chiller shown. In the embodiment of the present disclosure, the control device of the chiller is used as the execution subject to illustrate the solution.

[0119] Step S501: The control device detects the current outlet water temperature of the chiller.

[0120] Step S502: When the current outlet water temperature is lower than the target temperature, the control device controls the chiller to start unloading and reduce the IGV opening.

[0121] Step S503: When the current outlet water temperature is greater than or equal to the target temperature, the control device controls the chiller to continue to operate and the bypass pipeline remains cut off.

[0122] Step S504: the control device obtains the current current of the centrifugal compressor.

[0123] In step S505, the control device calculates the group load according to the ratio of the current current to the maximum current and the current IGV opening.

[0124] Step S506: When the unit load is less than or equal to the set threshold, the control device controls the IGV opening to be kept at the minimum, controls the bypass pipeline to be turned on, and sets the initial conduction opening of the bypass pipeline to the current conduction opening. When the unit load is greater than the set threshold, return to step S501 to determine whether to continue unloading according to the current outlet water temperature. If unloading is required, the IGV opening is further reduced in step S502.

[0125] Step S507: the control device detects the current outlet water temperature of the chiller.

[0126] Step S508, if Ts-△T<t<Ts, the control device adjusts the conduction opening of the bypass pipeline according to the current outlet water temperature of the unit. Otherwise, the control device controls the chiller to stop unloading. To avoid the unit automatically shutting down for protection. Optionally, the control device controlling the chiller to stop unloading may include controlling the bypass pipeline to be cut off, or controlling the IGV opening to restore the initial opening.

[0127] Step S509: the control device obtains the current current of the centrifugal compressor.

[0128] In step S510, the control device calculates the group load according to the ratio of the current current to the maximum current and the current conduction opening of the bypass line.

[0129] Furthermore, according to the ratio of the current current to the maximum current and the current conduction opening of the bypass line, the computer group load may include:

[0130] According to the ratio of the current current to the maximum current and the corresponding relationship between the conductance opening of the bypass line and the unit load, the ratio of the current current to the maximum current and the unit load corresponding to the current conductance opening of the bypass line are determined.

[0131] Here, the ratio of the current current to the maximum current and the corresponding relationship between the opening degree of the bypass pipeline and the unit load can be stored in the database in the form of a one-to-one correspondence data table. After obtaining the ratio of the current current to the maximum current and the current opening degree of the bypass pipeline, the current unit load corresponding to the ratio of the current current to the maximum current and the current opening degree of the bypass pipeline can be obtained by querying the database.

[0132] Alternatively, the corresponding relationship between the ratio of the current current to the maximum current, the opening degree of the bypass pipeline and the unit load can be sampled and fitted using a formula. After obtaining the ratio of the current current to the maximum current and the current opening degree of the bypass pipeline, substituting the ratio of the current current to the maximum current and the current opening degree of the bypass pipeline into the formula, the current unit load corresponding to the ratio of the current current to the maximum current and the current opening degree of the bypass pipeline can be obtained.

[0133] Specifically, the unit load is calculated in the following manner:

[0134] Calculate Z = b1W 3 +b2W 2 Y + b3WY + b4W 2 ;

[0135] Where Z is the unit load, W is the current opening degree ratio of the bypass pipeline, Y is the ratio of the current current to the maximum current, and b1 to b4 are fitting coefficients, with 0 > b2, 0 < b1 < b4 < b3.

[0136] As can be seen from the above formula, the change in the unit load and the opening degree of the bypass pipeline is a non-linear relationship, and the change with the ratio of the current current to the maximum current is also non-linear. This means that as the current opening degree of the bypass pipeline and the current current change, the change in the unit load is not linear but shows a certain curve characteristic. By adjusting the fitting coefficients, the calculation of the unit load can be further adjusted and optimized to better meet the control requirements, thereby achieving more efficient energy utilization and system performance.

[0137] Step S511, when the unit load is greater than the set threshold and the current outlet water temperature is greater than the target temperature, control the bypass pipeline to be truncated.

[0138] Here, when the unit load is greater than the set threshold, further determine whether the current outlet water temperature is greater than the target temperature to determine whether there is a load unloading requirement. If the current outlet water temperature is greater than the target temperature, it indicates that the unit load has met the operating conditions and there is no need to continue unloading. At this time, the bypass pipeline can be controlled to be truncated. If the unit load is less than the set threshold and / or the current outlet water temperature is less than or equal to the target temperature, it means that it is necessary to return to step S507 and continue to adjust the current opening degree of the bypass pipeline according to the current outlet water temperature.

[0139] In this way, through the control method for the chiller provided by the embodiment of the present disclosure, when the unit has a load reduction demand, the load is first reduced by adjusting the IGV opening; when the unit load drops below the set threshold and still needs to continue to reduce the load, the bypass line is connected through the opening adjustment device, and the actual load reduction demand is determined according to the current outlet water temperature to continue to adjust the opening, so that the high-pressure gas in the condenser enters the evaporator through the bypass line, which can reduce the compressor exhaust pressure, increase the compressor suction pressure, and then reduce the compressor The pressure ratio, the purpose of continuing to reduce the load of the unit. The load range can be widened from the original 50% to 100% to 10% to 100%. After the load range is widened, the corresponding IPLV is also improved, and the whole machine achieves the purpose of energy saving.

[0140] Combination Figure 6 As shown, the present disclosure provides a control device 60 for a centrifugal chiller, which is applied to Figure 1 The air-conditioning centrifugal chiller shown includes a temperature detection device 61 , an IGV opening control device 62 , a unit load calculation device 63 and a bypass pipeline opening control device 64 .

[0141] Among them, the temperature detection device 61 is configured to detect the current outlet water temperature of the chiller; the IGV opening control device 62 controls the chiller to start unloading and reduce the IGV opening when the current outlet water temperature is lower than the target temperature; the unit load calculation device 63 is configured to obtain the unit load under the current IGV opening; the bypass pipeline opening control device 64 is configured to control the IGV opening to remain at the minimum and control the bypass pipeline to be conductive when the unit load is less than or equal to the set threshold.

[0142] Combination Figure 7 As shown, the embodiment of the present disclosure provides a control device 70 for a centrifugal chiller, including a processor (processor) 700 and a memory (memory) 701. Optionally, the device 70 may also include a communication interface (Communication Interface) 702 and a bus 703. Among them, the processor 700, the communication interface 702, and the memory 701 can communicate with each other through the bus 703. The communication interface 702 can be used for information transmission. The processor 700 can call the logic instructions in the memory 701 to execute the control method for the centrifugal chiller of the above embodiment.

[0143] In addition, the logic instructions in the memory 701 described above may be implemented in the form of software functional units and when sold or used as independent products, may be stored in a computer-readable storage medium.

[0144] The memory 701, as a computer-readable storage medium, can be used to store software programs and computer-executable programs, such as the program instructions / modules corresponding to the methods in the embodiments of the present disclosure. The processor 700 executes functional applications and data processing by running the program instructions / modules stored in the memory 701, that is, implements the control method for the centrifugal chiller in the above embodiments.

[0145] The memory 701 may include a program storage area and a data storage area. Among them, the program storage area can store an operating system and application programs required for at least one function; the data storage area can store data created according to the use of the terminal device, etc. In addition, the memory 701 may include a high-speed random access memory and may also include a non-volatile memory.

[0146] Combined with Figure 8 As shown, the embodiments of the present disclosure provide a centrifugal chiller, including: a unit body 100 and the above control device 60(70) for the centrifugal chiller. The control device 60(70) for the centrifugal chiller is installed on the unit body 100. The installation relationship described here is not limited to being placed inside the unit body 100, but also includes installation connections with other components of the unit, including but not limited to physical connections, electrical connections, or signal transmission connections, etc. Those skilled in the art can understand that the control device 60(70) for the centrifugal chiller can be adapted to a feasible unit main body, and then implement other feasible embodiments.

[0147] The embodiments of the present disclosure provide a computer-readable storage medium storing computer-executable instructions, and the computer-executable instructions are set to execute the above control method for the centrifugal chiller.

[0148] The technical solutions of the embodiments of the present disclosure can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes one or more instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the embodiments of the present disclosure. The foregoing storage medium may be a non-transitory storage medium, such as: a USB flash drive, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk, or an optical disc, etc., which are various media that can store program codes.

[0149] The above description and the accompanying drawings fully illustrate the embodiments of the present disclosure, enabling those skilled in the art to practice them. Other embodiments may include structural, logical, electrical, process, and other changes. Embodiments merely represent possible variations. Unless explicitly required, individual components and functions are optional, and the order of operations may vary. Parts and features of some embodiments may be included in or replace parts and features of other embodiments. Moreover, the terms used in this application are only for describing embodiments and do not limit the claims. As used in the description of embodiments and claims, unless the context clearly indicates otherwise, the singular forms "a", "an", and "the" are intended to also include the plural forms. Similarly, as used in this application, the term "and / or" refers to any and all possible combinations of one or more of the associated listed items. Additionally, when used in this application, the term "comprise" and its variants "comprises" and / or "comprising" etc. mean the presence of the stated features, wholes, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or groups thereof. Without further limitation, an element defined by the statement "comprising one..." does not exclude the presence of additional identical elements in the process, method, or device comprising the element. In this document, each embodiment may focus on the differences from other embodiments, and the same or similar parts among the embodiments may be referred to each other. For the methods, products, etc. disclosed in the embodiments, if they correspond to the method parts disclosed in the embodiments, the relevant parts may refer to the description of the method parts.

[0150] Those skilled in the art can realize that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are executed in a hardware or software manner may depend on the specific application and design constraints of the technical solution. The skilled person may use different methods for each specific application to implement the described functions, but such implementation should not be considered to exceed the scope of the embodiments of the present disclosure. The skilled person can clearly understand that for the convenience and brevity of description, the specific working processes of the systems, devices, and units described above can refer to the corresponding processes in the foregoing method embodiments and will not be elaborated herein.

[0151] In the embodiments disclosed herein, the disclosed methods, products (including but not limited to devices, equipment, etc.) can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the units can be merely a logical function division. In actual implementation, there can be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Additionally, the displayed or discussed coupling or direct coupling or communication connection between each other can be through some interfaces. The indirect coupling or communication connection of the devices or units can be in electrical, mechanical, or other forms. The units described as separate components may or may not be physically separated. The components displayed as units may or may not be physical units, that is, they can be located in one place or distributed to multiple network units. Some or all of the units can be selected according to actual needs to implement this embodiment. Additionally, in the embodiments of the present disclosure, each functional unit can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit.

[0152] The flowcharts and block diagrams in the accompanying drawings illustrate the possible architectures, functions, and operations of systems, methods, and computer program products according to the embodiments of the present disclosure. In this regard, each block in the flowchart or block diagram can represent a module, a program segment, or a part of code that contains one or more executable instructions for implementing the specified logical function. In some alternative implementations, the functions marked in the blocks can occur in a different order than that marked in the accompanying drawings. For example, two consecutive blocks can actually be executed substantially in parallel, and they can sometimes be executed in the reverse order, which can depend on the functions involved. In the descriptions corresponding to the flowcharts and block diagrams in the accompanying drawings, the operations or steps corresponding to different blocks can also occur in a different order than that disclosed in the description. Sometimes, there is no specific order between different operations or steps. For example, two consecutive operations or steps can actually be executed substantially in parallel, and they can sometimes be executed in the reverse order, which can depend on the functions involved. Each block in the block diagram and / or flowchart, as well as the combination of blocks in the block diagram and / or flowchart, can be implemented by a dedicated hardware-based system for performing the specified functions or actions, or can be implemented by a combination of dedicated hardware and computer instructions.

Claims

1. A centrifugal chiller, comprising a centrifugal compressor, a condenser, and an evaporator that are sequentially connected by pipelines, characterized in that, Further comprising: A bypass pipeline, the inlet of the bypass pipeline is connected to the condenser, and the outlet of the bypass pipeline is connected to the evaporator; An opening adjustment device, arranged on the bypass pipeline, configured to controllably conduct or cut off the bypass pipeline.

2. The centrifugal chiller according to claim 1, wherein, The opening adjustment device is configured to conduct the bypass pipeline when the current outlet water temperature is less than the target temperature and the unit load is less than or equal to the set threshold.

3. The centrifugal chiller according to claim 2, characterized in that, The opening adjustment device is further configured to adjust the opening degree of the bypass pipeline according to the current outlet water temperature of the unit when the difference between the target temperature and the shutdown temperature difference is less than the current outlet water temperature and the current outlet water temperature is less than the target temperature.

4. A control method for a centrifugal chiller, characterized in that, The centrifugal chiller includes a centrifugal compressor, a condenser, and an evaporator connected in sequence through pipelines; and a bypass pipeline, the inlet of the bypass pipeline is connected to the condenser, and the outlet of the bypass pipeline is connected to the evaporator; An opening adjustment device, arranged on the bypass pipeline, configured to controllably conduct or cut off the bypass pipeline; The control method includes: Detecting the current outlet water temperature of the chiller; When the current outlet water temperature is less than the target temperature, controlling the chiller to start unloading and reducing the opening degree of the inlet guide vane IGV; Obtaining the unit load at the current IGV opening degree; When the unit load is less than or equal to the set threshold, controlling the IGV opening degree to remain the lowest and controlling the bypass pipeline to conduct.

5. The control method according to claim 4, wherein The obtaining the unit load at the current IGV opening degree includes: Obtaining the current current of the centrifugal compressor; Calculating the unit load according to the ratio of the current current to the maximum current and the current IGV opening degree.

6. The control method according to claim 5, wherein Calculating the unit load according to the ratio of the current current to the maximum current and the current IGV opening degree includes: Calculate Z = a1X 3 + a2X 2 Y + a3XY 2 + a4XY + a5X 2 + a6Y 2 ; Where Z is the unit load, X is the IGV opening degree ratio, Y is the ratio of the current current to the maximum current, and a1 to a6 are fitting coefficients, 0 > a1 > a5 > a3, 0 < a2 < a6 < a4.

7. The control method according to claim 4, characterized in that After controlling the bypass pipeline to conduct, further comprising: Detecting the current outlet water temperature of the chiller; When the difference between the target temperature and the shutdown temperature difference is less than the current outlet water temperature and the current outlet water temperature is less than the target temperature, adjusting the opening degree of the bypass pipeline according to the current outlet water temperature of the unit.

8. The control method according to claim 7, wherein Adjusting the opening degree of the bypass pipeline according to the current outlet water temperature of the unit includes: When Ts - △T < t < Ts - △T + m, adjusting the current opening degree of the bypass pipeline to W = W + 10%; When Ts - △T + a < t < Ts, adjusting the bypass pipeline to maintain the current opening degree W; Where Ts is the target temperature, △T is the shutdown temperature difference value of the chiller, m is the adjustment value, t is the current outlet water temperature, and W is the current opening degree of the bypass pipeline.

9. The control method according to claim 7, wherein After adjusting the opening degree of the bypass pipeline according to the current outlet water temperature of the chiller, further comprising: Calculating the unit load according to the current opening degree of the bypass pipeline; When the unit load is greater than the set threshold and the current outlet water temperature is greater than the target temperature, controlling the bypass pipeline to be cut off.

10. The control method according to claim 9, wherein The calculating the unit load according to the current opening degree of the bypass pipeline includes: Obtaining the current current of the centrifugal compressor; Calculate the unit load based on the ratio of the current current to the maximum current and the current opening degree of the bypass pipeline.

11. The control method according to claim 10, wherein Calculate the unit load based on the ratio of the current current to the maximum current and the current opening degree of the bypass pipeline, including: Calculate Z = b1W 3 + b2W 2 Y + b3WY + b4W 2 ; where Z is the unit load, W is the current opening degree ratio of the bypass pipeline, Y is the ratio of the current current to the maximum current, and b1 to b4 are fitting coefficients, with 0 > b2, 0 < b1 < b4 < b3.

12. A control device for a centrifugal chiller, characterized in that, The centrifugal chiller includes a centrifugal compressor, a condenser, and an evaporator connected in sequence through pipelines; and a bypass pipeline, the inlet of the bypass pipeline is connected to the condenser, and the outlet of the bypass pipeline is connected to the evaporator; An opening degree adjusting device is arranged on the bypass pipeline and is configured to controllably conduct or cut off the bypass pipeline; The control device includes: A temperature detection device configured to detect the current outlet water temperature of the chiller; An IGV opening degree control device that controls the chiller to start unloading and reduce the IGV opening degree when the current outlet water temperature is less than the target temperature; A unit load calculation device configured to obtain the unit load at the current IGV opening degree; A bypass pipeline opening degree control device configured to control the IGV opening degree to remain at the lowest level and control the bypass pipeline to conduct when the unit load is less than or equal to the set threshold.

13. A control device for a chiller, comprising a processor and a memory storing program instructions, characterized in that, The processor is configured to execute the control method for the chiller according to any one of claims 4 to 11 when running the program instructions.

14. A computer-readable storage medium storing program instructions, characterized in that, When running, the program instructions are used to cause the computer to execute the control method for the chiller according to any one of claims 4 to 11.

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