Screw unit control method, device and electronic equipment

Abstract

The application discloses a screw machine set control method and device and electronic equipment, and relates to the technical field of refrigeration equipment. The method comprises the following steps: in response to a machine set starting instruction, calculating a pressure difference value based on a suction pressure value and a discharge pressure value, and calculating a current fluctuation value based on a current value of a screw compressor; determining a basic loading rate according to the pressure difference value; correcting the basic loading rate according to the current fluctuation value to obtain a target loading rate; and outputting a pulse loading signal to a solenoid valve according to the target loading rate, so that the solenoid valve drives the sliding valve to move. The application can effectively improve the stability and adaptability of the screw machine set during the starting loading process.

Description

Technical Field

[0001] This application relates to the field of refrigeration equipment technology, specifically to a screw chiller control method, device, and electronic equipment. Background Technology

[0002] Taking screw chillers as an example, during start-up loading control, screw chillers typically use a simple step-by-step loading method based on the suction and discharge pressure difference and a fixed pressure difference threshold, such as controlling the solenoid valves to open at 20%, 50%, 75%, and 100% in stages. This simple step-by-step solenoid valve opening method results in uneven load regulation and poor control accuracy during start-up loading, leading to poor stability and adaptability of the screw chiller during the start-up loading process. Summary of the Invention

[0003] This application provides a screw compressor control scheme that can effectively improve the stability and adaptability of the screw compressor during the start-up and loading process.

[0004] The embodiments of this application provide the following technical solutions: According to one embodiment of this application, a screw compressor unit control method includes: responding to a unit start-up command, calculating a pressure difference value based on an intake pressure value and an exhaust pressure value, and calculating a current fluctuation value based on a current value of the screw compressor; determining a basic loading rate based on the pressure difference value; correcting the basic loading rate based on the current fluctuation value to obtain a target loading rate; and outputting a pulse loading signal to a solenoid valve according to the target loading rate, so that the solenoid valve drives a slide valve to move.

[0005] In some embodiments of this application, determining the basic loading rate based on the pressure difference value includes: calculating the average pressure difference value based on multiple pressure difference values ​​within a preset time window; and determining the preset basic loading rate corresponding to the preset pressure difference range in which the average pressure difference value is located.

[0006] In some embodiments of this application, the current fluctuation value includes the current harmonic distortion rate; the step of correcting the base loading rate based on the current fluctuation value to obtain the target loading rate includes: correcting the base loading rate based on the reference harmonic distortion rate and the current harmonic distortion rate to obtain the target loading rate; wherein, when the current harmonic distortion rate is greater than the reference harmonic distortion rate, the target loading rate is less than the base loading rate; when the current harmonic distortion rate is less than the reference harmonic distortion rate, the target loading rate is greater than the base loading rate.

[0007] In some embodiments of this application, the step of correcting the base loading rate based on the reference harmonic distortion rate and the current harmonic distortion rate to obtain the target loading rate includes: according to formula Vtarget =V base (α) THD ref -THD dk The target loading rate is calculated, where α is a preset correction coefficient, 0 < α ≤ 1, THD ref The reference harmonic distortion rate, THD dk V is the harmonic distortion rate of the current. base V is the base loading rate. target The target loading rate is [value].

[0008] In some embodiments of this application, after correcting the base loading rate based on the current fluctuation value to obtain the target loading rate, the method further includes: if the current harmonic distortion rate exceeds a preset maximum distortion rate, then reducing the target loading rate or setting the target loading rate to zero.

[0009] In some embodiments of this application, after correcting the base loading rate based on the current fluctuation value to obtain the target loading rate, the method further includes: if the load change rate of the screw compressor exceeds a preset load change rate threshold, then reducing the target loading rate or setting the target loading rate to zero.

[0010] In some embodiments of this application, after correcting the base loading rate based on the current fluctuation value to obtain the target loading rate, the method further includes: when the temperature difference between the inlet and outlet water of the evaporator is greater than a preset temperature difference threshold, determining the compensation rate corresponding to the temperature difference between the inlet and outlet water; and superimposing the compensation rate onto the target loading rate.

[0011] In some embodiments of this application, the step of outputting a pulse loading signal to the solenoid valve according to the target loading rate includes: during the process of outputting the pulse loading signal to the solenoid valve, when the rate of change of the differential pressure value is greater than a preset rate of change of differential pressure value, adjusting the duty cycle of the pulse loading signal to reduce the moving speed of the slide valve until the rate of change of the differential pressure value is less than the preset rate of change of differential pressure value.

[0012] According to one embodiment of this application, a screw compressor unit control device includes: a calculation module, configured to: calculate a pressure difference value based on an intake pressure value and an exhaust pressure value, and calculate a current fluctuation value based on a screw compressor current value, in response to a unit start-up command; a rate determination module, configured to: determine a basic loading rate based on the pressure difference value; a rate correction module, configured to: correct the basic loading rate based on the current fluctuation value to obtain a target loading rate; and a control module, configured to: output a pulse loading signal to a solenoid valve according to the target loading rate, so that the solenoid valve drives a slide valve to move.

[0013] According to another embodiment of this application, a storage medium stores a computer program thereon, which, when executed by a processor of an electronic device, causes the electronic device to perform the methods described in the embodiments of this application.

[0014] According to another embodiment of this application, an electronic device may include: a memory storing a computer program; and a processor reading the computer program stored in the memory to execute the methods described in the embodiments of this application.

[0015] According to another embodiment of this application, a computer program product or computer program includes computer instructions stored in a computer-readable storage medium. A processor of an electronic device reads the computer instructions from the computer-readable storage medium and executes the computer instructions, causing the electronic device to perform the methods provided in the various optional implementations described in the embodiments of this application.

[0016] In this embodiment, in response to the unit start-up command, a pressure difference value is calculated based on the intake pressure value and the exhaust pressure value, and a current fluctuation value is calculated based on the current value of the screw compressor; a basic loading rate is determined based on the pressure difference value; the basic loading rate is corrected based on the current fluctuation value to obtain a target loading rate; and a pulse loading signal is output to the solenoid valve based on the target loading rate to drive the slide valve to move its position.

[0017] In this embodiment of the application, when the screw compressor unit is started and loaded, the basic loading rate is determined based on the pressure difference between the suction pressure and the discharge pressure, and the target loading rate is obtained by correcting the basic loading rate based on the current fluctuation. The target loading rate is then used to output a pulse loading signal to the solenoid valve, which enables the solenoid valve to drive the slide valve to move continuously and smoothly. This allows for smooth load adjustment and effectively adapts to the suction and discharge pressure difference and current fluctuation of the screw compressor during start-up loading. Overall, this can effectively improve the stability and adaptability of the screw compressor unit during the start-up loading process. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A flowchart of a screw compressor control method according to an embodiment of this application is shown.

[0020] Figure 2 A block diagram of a screw compressor control device according to an embodiment of this application is shown.

[0021] Figure 3 A block diagram of an electronic device according to an embodiment of this application is shown. Detailed Implementation

[0022] The present disclosure will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the embodiments provided herein are merely illustrative of the present disclosure and are not intended to limit the present disclosure. Furthermore, the embodiments provided below are some embodiments for implementing the present disclosure, and not all embodiments for implementing the present disclosure. Unless otherwise specified, the technical solutions described in the embodiments of the present disclosure can be implemented in any combination. It should be noted that, in the embodiments of this disclosure, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a method or apparatus that includes a list of elements includes not only the elements expressly described, but also other elements not expressly listed, or elements inherent to implementing the method or apparatus. Without further limitations, an element defined by the phrase "comprising a..." does not exclude the presence of other related elements (e.g., steps in the method or units in the apparatus; for example, a unit may be a portion of circuitry, a portion of a processor, a portion of a program or software, etc.) in the method or apparatus that includes that element. For example, the screw compressor control method provided in this disclosure includes a series of steps, but the screw compressor control method provided in this disclosure is not limited to the steps described. Similarly, the screw compressor control device provided in this disclosure includes a series of units, but the device provided in this disclosure is not limited to the units explicitly described, but may also include units that need to be set up to obtain relevant information or to process information. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this disclosure. It is understood that in the specific implementation of this application, relevant data is involved. When the embodiments in this application are applied to specific products or technologies, user permission or consent is required, and the collection, use and processing of relevant data must comply with the relevant laws, regulations and standards of the relevant countries and regions.

[0023] Taking screw chillers as an example, during start-up loading control, screw chillers typically use a simple step-by-step loading method based on the suction and discharge pressure difference and a fixed pressure difference threshold, such as controlling the solenoid valves to open at 20%, 50%, 75%, and 100% in stages. This simple step-by-step solenoid valve opening method results in uneven load regulation and poor control accuracy during start-up loading, leading to poor stability and adaptability of the screw chiller during the start-up loading process.

[0024] To address these issues, this application provides a screw compressor control scheme that can effectively improve the stability and adaptability of the screw compressor during the start-up and loading process.

[0025] The following is a detailed description of the relevant embodiments of the screw compressor control scheme provided in this application.

[0026] Figure 1 A flowchart illustrating a screw compressor control method according to an embodiment of this application is shown schematically. The execution entity of this screw compressor control method can be an electronic device or a server. The electronic device can be the screw compressor's own control module, a remote control, a wired controller, a mobile phone, a computer, a smartwatch, or other home appliances, etc., and the server can be a cloud server or a physical server, etc.

[0027] For example, in one embodiment of this application, the execution entity of the screw compressor control method can be the screw compressor's own control module. The control module may include a processor and a memory, and the memory stores a computer program. Thus, the processor in the screw compressor's control module can read the computer program stored in the memory to execute the methods of the various embodiments of this application.

[0028] A screw compressor unit may include a screw compressor, an evaporator, a condenser, and a solenoid valve for controlling the position of a slide valve. The solenoid valve may include a loading solenoid valve and an unloading solenoid valve. Pressure sensors for detecting suction and discharge pressure values ​​may be installed on the compressor's suction and discharge lines, respectively. A current transformer may be installed to detect the current value of the screw compressor.

[0029] like Figure 1 As shown, the screw compressor control method may include steps S110 to S140.

[0030] Step S110: In response to the unit start-up command, calculate the pressure difference value based on the intake pressure value and the exhaust pressure value, and calculate the current fluctuation value based on the screw compressor current value; Step S120: Determine the foundation loading rate based on the pressure difference value; Step S130: Correct the base loading rate based on the current fluctuation value to obtain the target loading rate; Step S140: Output a pulse loading signal to the solenoid valve according to the target loading rate, so that the solenoid valve drives the slide valve to move position.

[0031] After the executing entity detects the unit start-up command for the screw compressor unit, it can collect the suction pressure Ps, discharge pressure Pd, and current I of the screw compressor in the screw compressor unit. Based on the suction and discharge pressure values, the pressure difference ΔP (ΔP = Pd - Ps) can be calculated; based on the current I, the current fluctuation value ΔI, reflecting the current fluctuation of the screw compressor, can be calculated. The current fluctuation value may include the current harmonic distortion rate and / or the rate of change of current value, etc.

[0032] The foundation loading rate V is determined based on the pressure difference value ΔP. base Base loading rate V base The foundation loading rate is determined based on the differential pressure value. The foundation loading rate is then corrected based on the current fluctuation value ΔI to obtain the target loading rate V. target Target loading rate V target That is, the corrected loading rate.

[0033] The target loading rate is dynamically and precisely determined based on the suction and discharge pressure difference and current fluctuation of the screw compressor during startup loading. According to the target loading rate, a pulse loading signal is output to the solenoid valve (such as a loading solenoid valve), which enables the solenoid valve to drive the slide valve to move continuously and smoothly. This allows the slide valve to move continuously and smoothly to the target load position to complete the startup loading. Thus, the startup loading process can smoothly adjust the load and adapt to the suction and discharge pressure difference and current fluctuation.

[0034] The executing entity can execute steps S110 to S140 once every preset control period Δt.

[0035] In summary, using the method described in this embodiment, when the screw compressor unit is started and loaded, the basic loading rate is determined based on the pressure difference between the suction pressure and the discharge pressure, and the target loading rate is obtained by correcting the basic loading rate based on the current fluctuation. A pulse loading signal is output to the solenoid valve based on the target loading rate, which enables the solenoid valve to drive the slide valve to move continuously and smoothly, thereby smoothly adjusting the load and effectively adapting to the suction and discharge pressure difference and current fluctuation of the screw compressor during start-up loading. Overall, this can effectively improve the stability and adaptability of the screw compressor unit during the start-up loading process.

[0036] The following description Figure 1 Further optional specific embodiments are provided for each step performed when controlling the screw compressor unit under the example.

[0037] In one embodiment, step S110, determining the basic loading rate based on the differential pressure value, includes: calculating the average differential pressure value based on multiple differential pressure values ​​within a preset time window; and determining the preset basic loading rate corresponding to the preset differential pressure range in which the average differential pressure value is located.

[0038] In this embodiment, a preset time window T is introduced. window Within a preset time window, multiple differential pressure values ​​can be continuously collected, and the average of these values ​​(i.e., the differential pressure mean) can be calculated. Furthermore, a preset differential pressure range corresponding to the preset base loading rate can be determined. In this way, multiple differential pressure values ​​can be smoothed, avoiding random errors in determining the base loading rate from single-point sampling of differential pressure values, thereby further improving the accuracy of base loading rate determination.

[0039] Multiple different preset pressure difference ranges can be set in advance, and each preset pressure difference range has a corresponding preset basic loading rate. In this way, the preset pressure difference range where the average pressure difference is located can be determined to correspond to the preset basic loading rate.

[0040] Furthermore, in one specific method, determining the preset base loading rate corresponding to the preset pressure difference range where the average pressure difference value lies can include: if the preset pressure difference range where the average pressure difference value lies is "the average pressure difference value μΔP ≥ the preset average value P", then... ref At this point, it is determined that the screw compressor unit has entered a high-load rapid loading mode, and the corresponding preset base loading rate is the first rate v1; if the preset differential pressure range where the average differential pressure value is located is "average differential pressure value μΔP < preset average value P", then the screw compressor unit is considered to have entered a high-load rapid loading mode, and the corresponding preset base loading rate is the first rate v1. ref At this point, it is determined that the screw compressor unit has entered a low-load slow loading mode, and the corresponding preset basic loading rate is the second rate v2; where v1 > v2.

[0041] Among them, the preset mean P refThe first speed v1 and the second speed v2 can be set according to actual conditions, and this application does not impose any special limitations on them. For example, in one example, P ref It can be set to 0.3MPa, v1 can be set to 5% / S, and v2 can be set to 2% / S.

[0042] Furthermore, in some implementations, the standard deviation σ can be calculated based on multiple differential pressure values ​​within a preset time window. ΔP If the standard deviation σ ΔP If the pressure difference is greater than or equal to the preset standard deviation, the preset time window will be extended by a preset duration to obtain more pressure difference values, thereby obtaining a more stable average pressure difference and further improving the accuracy of the basic loading rate determination.

[0043] Optionally, in other embodiments, in step S110, determining the basic loading rate based on the pressure difference value includes: determining the preset basic loading rate corresponding to the preset pressure difference range in which the pressure difference value is located.

[0044] In one embodiment, the current fluctuation value includes the current harmonic distortion rate; in step S130, the base loading rate is corrected based on the current fluctuation value to obtain the target loading rate, which may include: correcting the base loading rate based on the reference harmonic distortion rate and the current harmonic distortion rate to obtain the target loading rate; wherein, when the current harmonic distortion rate is greater than the reference harmonic distortion rate, the target loading rate is less than the base loading rate; when the current harmonic distortion rate is less than the reference harmonic distortion rate, the target loading rate is greater than the base loading rate.

[0045] In this embodiment, the current fluctuation value calculated based on the current value of the screw compressor includes the current harmonic distortion rate. The current harmonic distortion rate can reflect the current fluctuation of the screw compressor caused by power grid quality fluctuations. The target loading rate is obtained by correcting the basic loading rate according to the current harmonic distortion rate. When a pulse loading signal is output to the solenoid valve according to the target loading rate, the adaptive capability of the screw turbine unit to the current fluctuation of the screw compressor caused by power grid quality during the start-up loading process can be further improved.

[0046] Specifically, when the target loading rate is obtained by correcting the base loading rate based on the current harmonic distortion rate (THD), the current harmonic distortion rate (THD) is... dk Greater than the reference harmonic distortion rate (THD) ref When this occurs, it indicates severe harmonic pollution in the power grid, necessitating a reduction in the loading rate to prevent motor overload or vibration. In this case, the target loading rate is less than the base loading rate (i.e., the target loading rate is obtained by actively reducing the base loading rate). Current harmonic distortion rate (THD) dk Less than the reference harmonic distortion rate (THD) refWhen the target loading rate is greater than the base loading rate (i.e., the target loading rate is obtained by actively increasing the base loading rate), it indicates that the power grid quality is good and the loading rate can be appropriately increased. Additionally, the current harmonic distortion rate (THD) is also considered. dk Equal to the reference harmonic distortion rate (THD) ref At that time, the target loading rate can be equal to the base loading rate.

[0047] Furthermore, in one embodiment, the base loading rate is corrected based on the reference harmonic distortion rate and the current harmonic distortion rate to obtain the target loading rate. Specifically, this may include: according to formula V target =V base (α) THD ref -THD dk The target loading rate is calculated, where α is a preset correction coefficient, 0 < α ≤ 1, THD ref For reference harmonic distortion rate, THD dk V is the harmonic distortion rate of the current. base Based on the load rate, V target Target loading rate.

[0048] In this specific implementation, a modified model V is specifically designed. target =V base (α) THD ref -THD dk ), in the current harmonic distortion rate (THD) dk Less than the reference harmonic distortion rate (THD) ref At that time, the target loading rate can be obtained by precisely increasing the base loading rate; current harmonic distortion rate (THD) dk Greater than the reference harmonic distortion rate (THD) ref At this time, the target loading rate can be obtained by precisely reducing the base loading rate; in addition, the current harmonic distortion rate (THD) can be reduced. dk Equal to the reference harmonic distortion rate (THD) ref At this time, the target loading rate can be equal to the base loading rate. Reference harmonic distortion rate (THD) ref For the purposes of this application, no specific size is specified for comparison. For example, in one example, the reference harmonic distortion rate (THD) is used. ref It is 5%.

[0049] Optionally, in other embodiments, the base loading rate is corrected based on the reference harmonic distortion rate and the current harmonic distortion rate to obtain the target loading rate. Specifically, this may include: adjusting the base loading rate based on the current harmonic distortion rate (THD). dk Less than the reference harmonic distortion rate (THD) refAt that time, the target loading rate is obtained by increasing the basic loading rate by a predetermined first rate; current harmonic distortion rate (THD) dk Greater than the reference harmonic distortion rate (THD) ref At that time, the target loading rate is obtained by reducing the base loading rate by a predetermined second rate; in addition, the current harmonic distortion rate (THD) is... dk Equal to the reference harmonic distortion rate (THD) ref At that time, the target loading rate can be equal to the base loading rate.

[0050] Current Harmonic Distortion Rate (THD) dk The specific calculation can be obtained using the following formula: ; Where I1 is the effective value of the fundamental current, I n The effective value of the nth harmonic current is given. The effective values ​​of the fundamental current and harmonic current can be obtained by performing a fast Fourier transform on the current values.

[0051] Furthermore, in one embodiment, after correcting the base loading rate based on the current fluctuation value to obtain the target loading rate, the method may further include: reducing the target loading rate or setting the target loading rate to zero when the current harmonic distortion rate exceeds a preset maximum distortion rate. The preset maximum distortion rate is pre-set, and its specific value is not specifically limited in this application.

[0052] Preset a maximum distortion rate (THD) max When the current harmonic distortion rate (THD) is monitored dk THD exceeding the preset maximum distortion rate max When switching from normal loading mode to harmonic suppression mode, the target loading rate is forcibly reduced or set to zero (setting the target loading rate to zero means pausing the output pulse loading signal to the solenoid valve and pausing loading). This can further and reliably prevent abnormalities such as overload or vibration of the ground motor caused by grid harmonic pollution, and further improve the stability of the loading process and the safety of equipment operation.

[0053] Furthermore, in one embodiment, after correcting the base loading rate based on the current fluctuation value to obtain the target loading rate, the method may further include: if the load change rate of the screw compressor exceeds a preset load change rate threshold, then reducing the target loading rate or setting the target loading rate to zero. The preset load change rate threshold is pre-set, and its specific size is not specifically limited in this application.

[0054] By monitoring the load change rate ΔL of the screw compressor, if the load change rate ΔL of the screw compressor exceeds the preset load change rate threshold value ΔL maxIt also forces a reduction in the target loading rate or sets the target loading rate to zero (setting the target loading rate to zero means pausing the output pulse loading signal to the solenoid valve and pausing loading), thereby further and timely and reliably preventing abnormal vibrations of the compressor or motor overload caused by sudden load changes, and further improving the stability of the loading process and the safety of equipment operation.

[0055] The load change rate ΔL of a screw compressor can be calculated using the following formula: ; Where Lreal is the load of the screw compressor in the current control cycle, Llast is the load of the screw compressor in the previous control cycle, and Δt is the preset control cycle. The load of the screw compressor can be determined based on existing load detection methods, and this application does not impose any special limitations on this.

[0056] Furthermore, in one embodiment, after correcting the base loading rate based on the current fluctuation value to obtain the target loading rate, the method may further include: when the temperature difference between the inlet and outlet water of the evaporator is greater than a preset temperature difference threshold, determining the compensation rate corresponding to the temperature difference between the inlet and outlet water; and superimposing the compensation rate onto the target loading rate.

[0057] This embodiment further introduces a temperature feedforward compensation mechanism. When the temperature difference between the inlet and outlet water of the evaporator exceeds a preset temperature difference threshold, the compensation rate corresponding to the temperature difference is superimposed on the target loading rate. Then, a pulse loading signal can be output to the solenoid valve based on the target loading rate with the superimposed compensation rate. In this way, the screw chiller unit can detect and respond to load demands in advance during startup, further improving response speed and control accuracy.

[0058] The temperature difference between the inlet and outlet water of the evaporator can be equal to the return water temperature of the evaporator minus the chilled water outlet temperature. The preset temperature difference threshold is pre-set, and its specific value is not specifically limited in this application. The compensation rate corresponding to different difference ranges can be preset, thereby determining the compensation rate corresponding to the current inlet and outlet water temperature difference.

[0059] In one embodiment, outputting a pulse loading signal to the solenoid valve according to the target loading rate finally determined in any of the foregoing embodiments may include: during the process of outputting the pulse loading signal to the solenoid valve, when the rate of change of the differential pressure value is greater than the preset rate of change of differential pressure value, adjusting the duty cycle of the pulse loading signal to reduce the moving speed of the slide valve until the rate of change of differential pressure value is less than the preset rate of change of differential pressure value.

[0060] When a pulse loading signal is output to the solenoid valve according to the target loading rate finally determined in any of the foregoing embodiments, the target loading rate V is used as the basis for determining the target loading rate V. targetThe duty cycle (Duty) and frequency (Freq) of the pulse loading signal are calculated in reverse, and the pulse loading signal is output to the solenoid valve according to the duty cycle (Duty) and frequency (Freq). The moving speed of the slide valve is proportional to the opening time of the solenoid valve. By controlling the on / off duty cycle of the solenoid valve through the pulse loading signal, the stepless smooth adjustment of the slide valve can be achieved.

[0061] During the process of outputting a pulse loading signal to the solenoid valve, if the rate of change of the differential pressure value is greater than the preset rate of change of differential pressure (i.e., a sudden change occurs and the magnitude of the change exceeds the preset impact limit), the duty cycle of the pulse loading signal is dynamically adjusted. This can precisely reduce the moving speed of the slide valve until the rate of change of differential pressure value is less than the preset rate of change of differential pressure value. In this way, the pressure overshoot phenomenon can be suppressed in a timely and effective manner during the start-up loading process.

[0062] The preset differential pressure change rate can be set according to actual conditions, and the specific value is not specifically limited in this application. For example, in one example, the preset differential pressure change rate can be 0.1 MPa / s. Furthermore, when adjusting the duty cycle of the pulse loading signal to reduce the moving speed of the slide valve, the duty cycle can be reduced by a predetermined percentage (e.g., 50%). Additionally, after reducing the moving speed of the slide valve until the differential pressure change rate is less than the preset differential pressure change rate (i.e., after the differential pressure stabilizes), the duty cycle can be restored to its original value.

[0063] To facilitate better implementation of the screw compressor control method provided in this application, this application also provides a screw compressor control device based on the above-described screw compressor control method. The meanings of the terms used are the same as in the screw compressor control method described above, and specific implementation details can be found in the descriptions within the method embodiments. Figure 2 A block diagram of a screw compressor control device according to an embodiment of this application is shown.

[0064] like Figure 2 As shown, the screw compressor unit control device 200 may include: a calculation module 210, which can be used to: calculate a pressure difference value based on the suction pressure value and the discharge pressure value in response to the unit start-up command, and calculate a current fluctuation value based on the current value of the screw compressor; a rate determination module 220, which can be used to: determine a basic loading rate based on the pressure difference value; a rate correction module 230, which can be used to: correct the basic loading rate based on the current fluctuation value to obtain a target loading rate; and a control module 240, which can be used to: output a pulse loading signal to the solenoid valve according to the target loading rate, so that the solenoid valve drives the slide valve to move.

[0065] In some embodiments of this application, when determining the basic loading rate based on the pressure difference value, the rate determination module 220 can be used to: calculate the average pressure difference value based on multiple pressure difference values ​​within a preset time window; and determine the preset basic loading rate corresponding to the preset pressure difference range in which the average pressure difference value is located.

[0066] In some embodiments of this application, the current fluctuation value includes the current harmonic distortion rate; when the base loading rate is corrected based on the current fluctuation value to obtain the target loading rate, the rate correction module 230 can be used to: correct the base loading rate based on the reference harmonic distortion rate and the current harmonic distortion rate to obtain the target loading rate; wherein, when the current harmonic distortion rate is greater than the reference harmonic distortion rate, the target loading rate is less than the base loading rate; when the current harmonic distortion rate is less than the reference harmonic distortion rate, the target loading rate is greater than the base loading rate.

[0067] In some embodiments of this application, when the base loading rate is corrected based on the reference harmonic distortion rate and the current harmonic distortion rate to obtain the target loading rate, the rate correction module 230 can be used to: [follow formula V] target =V base (α) THD ref -THD dk The target loading rate is calculated, where α is a preset correction coefficient, 0 < α ≤ 1, THD ref The reference harmonic distortion rate, THD dk V is the harmonic distortion rate of the current. base V is the base loading rate. target The target loading rate is [value].

[0068] In some embodiments of this application, after the basic loading rate is corrected according to the current fluctuation value to obtain the target loading rate, the device further includes an adjustment module that can be used to: reduce the target loading rate or set the target loading rate to zero if the current harmonic distortion rate exceeds a preset maximum distortion rate.

[0069] In some embodiments of this application, after the basic loading rate is corrected according to the current fluctuation value to obtain the target loading rate, the device further includes an adjustment module that can be used to: reduce the target loading rate or set the target loading rate to zero if the load change rate of the screw compressor exceeds a preset load change rate threshold.

[0070] In some embodiments of this application, after the basic loading rate is corrected according to the current fluctuation value to obtain the target loading rate, the device further includes an adjustment module that can be used to: determine the compensation rate corresponding to the inlet and outlet water temperature difference when the inlet and outlet water temperature difference of the evaporator is greater than a preset temperature difference threshold; and add the compensation rate to the target loading rate.

[0071] In some embodiments of this application, when the pulse loading signal is output to the solenoid valve according to the target loading rate, the control module 240 can be used to: during the process of outputting the pulse loading signal to the solenoid valve, when the rate of change of the differential pressure value is greater than the preset rate of change of differential pressure value, adjust the duty cycle of the pulse loading signal to reduce the moving speed of the slide valve until the rate of change of differential pressure value is less than the preset rate of change of differential pressure value.

[0072] It should be noted that although several modules or units for the device used to perform actions have been mentioned in the detailed description above, this division is not mandatory. In fact, according to the embodiments of this application, the features and functions of two or more modules or units described above can be embodied in one module or unit. Conversely, the features and functions of one module or unit described above can be further divided and embodied by multiple modules or units.

[0073] Furthermore, embodiments of this application also provide an electronic device, such as... Figure 3 As shown, Figure 3 A block diagram of an electronic device according to an embodiment of this application is shown, specifically: The electronic device may include components such as a processor 301 with one or more processing cores, a memory 302 with one or more computer-readable storage media, a power supply 303, and an input unit 304. Those skilled in the art will understand that... Figure 3 The electronic device structure shown does not constitute a limitation on the electronic device and may include more or fewer components than shown, or combine certain components, or have different component arrangements. Wherein: The processor 301 is the control center of the electronic device, connecting various parts of the computer device via various interfaces and lines. It executes software programs and / or modules stored in the memory 302, and calls data stored in the memory 302, to perform various functions and process data. Optionally, the processor 301 may include one or more processing cores; preferably, the processor 301 may integrate an application processor and a modem processor, wherein the application processor mainly handles the operating system, user page, and applications, and the modem processor mainly handles wireless communication. It is understood that the modem processor may not be integrated into the processor 301.

[0074] The memory 302 can be used to store software programs and modules. The processor 301 executes various functional applications and data processing by running the software programs and modules stored in the memory 302. The memory 302 may mainly include a program storage area and a data storage area. The program storage area may store the operating system, application programs required for at least one function (such as sound playback function, image playback function, etc.), etc.; the data storage area may store data created according to the use of the electronic device, etc. In addition, the memory 302 may include high-speed random access memory, and may also include non-volatile memory, such as at least one disk storage device, flash memory device, or other volatile solid-state storage device. Accordingly, the memory 302 may also include a memory controller to provide the processor 301 with access to the memory 302.

[0075] The electronic device also includes a power supply 303 that supplies power to various components. Preferably, the power supply 303 can be logically connected to the processor 301 through a power management system, thereby enabling functions such as charging, discharging, and power consumption management through the power management system. The power supply 303 may also include one or more DC or AC power supplies, recharging systems, power fault detection circuits, power converters or inverters, power status indicators, and other arbitrary components.

[0076] The electronic device may also include an input unit 304, which can be used to receive input digital or character information and generate keyboard, mouse, joystick, optical or trackball signal inputs related to user settings and function control.

[0077] Although not shown, the electronic device may also include a display unit, etc., which will not be described in detail here. Specifically, in this embodiment, the processor 301 in the electronic device can load the executable files corresponding to the processes of one or more computer programs into the memory 302 according to the following instructions, and the processor 301 runs the computer programs stored in the memory 302, thereby realizing the various functions in the foregoing embodiments of this application.

[0078] For example, processor 301 can perform the following actions in response to a unit start-up command: calculate a pressure difference value based on the intake pressure value and the exhaust pressure value, and calculate a current fluctuation value based on the current value of the screw compressor; determine a basic loading rate based on the pressure difference value; correct the basic loading rate based on the current fluctuation value to obtain a target loading rate; and output a pulse loading signal to the solenoid valve based on the target loading rate to cause the solenoid valve to drive the slide valve to move.

[0079] Those skilled in the art will understand that all or part of the steps in the various methods of the above embodiments can be performed by a computer program, or by a computer program controlling related hardware. The computer program can be stored in a computer-readable storage medium and loaded and executed by a processor.

[0080] Therefore, embodiments of this application also provide a storage medium storing a computer program that can be loaded by a processor to execute the steps in any of the methods provided in embodiments of this application.

[0081] The storage medium can be a computer-readable storage medium, which may include: read-only memory (ROM), random access memory (RAM), disk or optical disk, etc.

[0082] Since the computer program stored in the storage medium can execute the steps of any of the methods provided in the embodiments of this application, the beneficial effects that the methods provided in the embodiments of this application can achieve can be realized. For details, please refer to the previous embodiments, which will not be repeated here.

[0083] According to another embodiment of this application, a computer program product or computer program includes computer instructions stored in a computer-readable storage medium. A processor of an electronic device reads the computer instructions from the computer-readable storage medium and executes the computer instructions, causing the electronic device to perform the methods provided in the various optional implementations described in the embodiments of this application.

[0084] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the embodiments disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein.

[0085] It should be understood that this application is not limited to the embodiments described above and shown in the accompanying drawings, but various modifications and changes can be made without departing from its scope.

Claims

1. A screw compressor unit control method, characterized in that, include: In response to the unit start-up command, the pressure difference value is calculated based on the intake pressure value and the exhaust pressure value, and the current fluctuation value is calculated based on the current value of the screw compressor; The foundation loading rate is determined based on the pressure difference value; The base loading rate is corrected based on the current fluctuation value to obtain the target loading rate; According to the target loading rate, a pulse loading signal is output to the solenoid valve so that the solenoid valve drives the slide valve to move.

2. The method according to claim 1, characterized in that, Determining the base loading rate based on the pressure difference value includes: The average pressure difference is calculated based on multiple pressure difference values ​​within a preset time window; The preset base loading rate is determined to correspond to the preset pressure difference range in which the average pressure difference is located.

3. The method according to claim 1, characterized in that, The current fluctuation value includes the current harmonic distortion rate; the step of correcting the base loading rate based on the current fluctuation value to obtain the target loading rate includes: The base loading rate is corrected based on the reference harmonic distortion rate and the current harmonic distortion rate to obtain the target loading rate; Wherein, when the current harmonic distortion rate is greater than the reference harmonic distortion rate, the target loading rate is less than the base loading rate; when the current harmonic distortion rate is less than the reference harmonic distortion rate, the target loading rate is greater than the base loading rate.

4. The method according to claim 3, characterized in that, The step of correcting the base loading rate based on the reference harmonic distortion rate and the current harmonic distortion rate to obtain the target loading rate includes: According to formula V target =V base (α) THD ref -THD dk The target loading rate is calculated, where α is a preset correction coefficient, 0 < α ≤ 1, THD ref The reference harmonic distortion rate, THD dk V is the harmonic distortion rate of the current. base V is the base loading rate. target The target loading rate is [value].

5. The method according to claim 3, characterized in that, After correcting the base loading rate based on the current fluctuation value to obtain the target loading rate, the method further includes: If the current harmonic distortion rate exceeds the preset maximum distortion rate, then the target loading rate is reduced or the target loading rate is set to zero.

6. The method according to claim 1, characterized in that, After correcting the base loading rate based on the current fluctuation value to obtain the target loading rate, the method further includes: If the load change rate of the screw compressor exceeds a preset load change rate threshold, the target loading rate is reduced or the target loading rate is set to zero.

7. The method according to claim 1, characterized in that, After correcting the base loading rate based on the current fluctuation value to obtain the target loading rate, the method further includes: When the temperature difference between the inlet and outlet water of the evaporator is greater than the preset temperature difference threshold, the compensation rate corresponding to the temperature difference between the inlet and outlet water is determined. The compensation rate is superimposed on the target loading rate.

8. The method according to any one of claims 1 to 7, characterized in that, The step of outputting a pulse loading signal to the solenoid valve according to the target loading rate includes: During the process of outputting the pulse loading signal to the solenoid valve, if the rate of change of the differential pressure value is greater than the preset rate of change of differential pressure, the duty cycle of the pulse loading signal is adjusted to reduce the moving speed of the slide valve until the rate of change of the differential pressure value is less than the preset rate of change of differential pressure.

9. A screw compressor control device, characterized in that, include: The calculation module is used to: calculate the pressure difference value based on the intake pressure value and the exhaust pressure value in response to the unit start-up command, and calculate the current fluctuation value based on the current value of the screw compressor; A rate determination module is used to: determine the foundation loading rate based on the pressure difference value; A rate correction module is used to: correct the base loading rate based on the current fluctuation value to obtain a target loading rate; The control module is used to: output a pulse loading signal to the solenoid valve according to the target loading rate, so that the solenoid valve drives the slide valve to move.

10. An electronic device, characterized in that, include: Memory, which stores computer programs; A processor reads a computer program stored in memory to perform the method described in any one of claims 1 to 8.

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