Control method and device of variable-frequency screw water chilling unit and variable-frequency screw water chilling unit

Abstract

The invention provides a control method and device of a variable-frequency screw water chilling unit and the variable-frequency screw water chilling unit. The control method comprises the steps that when it is determined that the compressor is started and operates stably, the actual starting time consumed by the compressor in the starting stage is obtained; when the actual starting duration is smaller than the set starting duration, an electronic expansion valve of the unit is controlled to execute a transition adjustment stage; or when the actual starting duration is larger than or equal to the set starting duration, the electronic expansion valve of the unit is controlled to execute the PI D adjusting stage. According to the control method and device of the variable-frequency screw water chilling unit and the variable-frequency screw water chilling unit, the change of the opening degree of the electronic expansion valve can be stably controlled, the requirement for load change of the press can be responded in time, and meanwhile the problem that the suction and exhaust pressure difference is too low is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrical appliances, and in particular to a control method and device of a variable frequency screw water chiller and the variable frequency screw water chiller. BACKGROUND

[0002] In related technologies, during the starting stage of the variable frequency screw water chiller, different chilled water temperatures result in different refrigerant pressures and evaporation temperatures, and thus higher requirements for the action adjustment of the electronic expansion valve. The existing control method generally adjusts the opening degree of the electronic expansion valve through the suction superheat degree or the discharge superheat degree PID. This method has the problems of inaccurate calculation, lower suction pressure alarm caused by too small opening degree of the electronic expansion valve, slow establishment of the suction and discharge pressure difference, and untimely action of the electronic expansion valve during the starting stage of the compressor and when the chilled water temperature is low, which cannot respond to the demand for load change of the compressor in time. SUMMARY

[0003] The present application provides a control method and device of a variable frequency screw water chiller and the variable frequency screw water chiller, to solve the defects in the prior art and achieve the following technical effects: smoothly controlling the change of the opening degree of the electronic expansion valve, responding to the demand for load change of the compressor in time, and avoiding the problem of too low suction and discharge pressure difference.

[0004] The control method of the variable frequency screw water chiller according to the first aspect of the present application comprises the following steps.

[0005] When it is determined that the compressor is started and stably operated, the actual starting time length of the compressor during the starting stage is obtained.

[0006] According to the actual starting time length being less than the set starting time length, the electronic expansion valve of the unit is controlled to perform a transition adjustment stage; or, according to the actual starting time length being greater than or equal to the set starting time length, the electronic expansion valve of the unit is controlled to perform a PID adjustment stage.

[0007] According to an embodiment of the present application, the step of controlling the electronic expansion valve of the unit to perform a transition adjustment stage specifically comprises the following steps.

[0008] The current descending rate of the evaporation pressure of the unit is obtained.

[0009] When the current descending rate is greater than a first set rate, the previous descending rate of the evaporation pressure of the unit is obtained, and the opening degree of the electronic expansion valve is adjusted according to the previous descending rate.

[0010] Or, when the current descending rate is less than or equal to the first set rate, the chilled water temperature of the unit is obtained, and the opening degree of the electronic expansion valve is adjusted according to the chilled water temperature.

[0011] Thus, the method can provide more accurate and intelligent electronic expansion valve control strategies during the startup and transition phases of the water chiller, thereby improving the stability and efficiency of the system, reducing energy waste, and enhancing overall performance. This method can adapt to different operating conditions and load changes to ensure that the water chiller always operates at its best.

[0012] According to an embodiment of the present application, in the case where the current drop rate is greater than the first set rate, the step of controlling the opening degree of the electronic expansion valve according to the last drop rate specifically includes:

[0013] In the case where the last drop rate is greater than the first set rate and greater than or equal to the second set rate, or the last drop rate is greater than or equal to the first set rate and greater than the second set rate, the electronic expansion valve is controlled to increase the first increase opening degree every first interval and continuously increase the first set number of times, then maintain the current opening degree for a set duration.

[0014] In the case where the last drop rate is less than or equal to the first set rate or less than the second set rate, or the last drop rate is less than the first set rate or less than or equal to the second set rate, the refrigeration inlet water temperature of the unit is obtained, and the opening degree of the electronic expansion valve is controlled according to the refrigeration inlet water temperature.

[0015] Thus, through these detailed control steps, the present application can ensure that the opening degree of the electronic expansion valve is adjusted in a timely and appropriate manner in the case where the evaporation pressure drop rate is fast, thereby maintaining the stability and efficiency of the water chiller.

[0016] According to an embodiment of the present application, in the case where the current drop rate is less than or equal to the first set rate, the step of controlling the opening degree of the electronic expansion valve according to the refrigeration inlet water temperature specifically includes:

[0017] Obtaining the actual evaporation pressure of the unit;

[0018] Determining the standard evaporation pressure interval of the unit according to the interval in which the refrigeration inlet water temperature is located;

[0019] Controlling the opening degree of the electronic expansion valve according to the comparison result of the actual evaporation pressure and the standard evaporation pressure interval.

[0020] Thus, through the above steps, the present application can achieve precise control of the opening degree of the electronic expansion valve, thereby optimizing the performance and energy efficiency of the water chiller.

[0021] According to one embodiment of the present application, the step of determining the standard evaporating pressure interval of the unit according to the interval of the chilled water inlet temperature specifically comprises:

[0022] In the case that the chilled water inlet temperature is in the first temperature interval, the standard evaporating pressure interval is the first pressure interval;

[0023] In the case that the chilled water inlet temperature is in the second temperature interval, the standard evaporating pressure interval is the second pressure interval;

[0024] In the case that the chilled water inlet temperature is in the third temperature interval, the standard evaporating pressure interval is the third pressure interval;

[0025] In the case that the chilled water inlet temperature is in the fourth temperature interval, the standard evaporating pressure interval is the fourth pressure interval;

[0026] wherein the order of the temperature intervals of the chilled water inlet temperature from large to small is: the fourth temperature interval, the third temperature interval, the second temperature interval, and the first temperature interval; the order of the maximum values of the standard evaporating pressure intervals from large to small is: the maximum value of the fourth pressure interval, the maximum value of the third pressure interval, the maximum value of the second pressure interval, and the maximum value of the first pressure interval; and the order of the minimum values of the standard evaporating pressure intervals from large to small is: the minimum value of the fourth pressure interval, the minimum value of the third pressure interval, the minimum value of the second pressure interval, and the minimum value of the first pressure interval.

[0027] According to one embodiment of the present application, the step of controlling the opening degree of the electronic expansion valve according to the comparison result of the actual evaporating pressure and the standard evaporating pressure interval specifically comprises:

[0028] in the case that the actual evaporating pressure is not in the standard evaporating pressure interval, the opening degree of the electronic expansion valve is increased or decreased according to the comparison result;

[0029] or, in the case that the actual evaporating pressure is in the standard evaporating pressure interval, the suction pressure and the discharge pressure of the compressor are obtained, and the opening degree of the electronic expansion valve is controlled according to the suction pressure and the discharge pressure.

[0030] In this way, through the above detailed control steps, the opening degree of the electronic expansion valve can be accurately and reasonably adjusted, so as to optimize the performance and energy efficiency of the water chiller unit.

[0031] According to one embodiment of the present application, the step of increasing or decreasing the opening degree of the electronic expansion valve according to the comparison result specifically comprises:

[0032] In the case that the actual evaporation pressure exceeds the standard evaporation pressure interval, then the electronic expansion valve is controlled to decrease a first decreasing opening degree every second interval time length;

[0033] Or, in the case that the evaporation pressure is lower than the standard evaporation pressure interval, then the electronic expansion valve is controlled to increase a second increasing opening degree every second interval time length.

[0034] In this way, the method can intelligently adjust the opening degree of the electronic expansion valve according to the actual operating condition, so as to maintain the evaporation pressure in the ideal standard interval.

[0035] According to an embodiment of the present application, the step of controlling the opening degree of the electronic expansion valve according to the suction pressure and the discharge pressure specifically comprises:

[0036] In the case that the difference between the discharge pressure and the suction pressure is less than the maximum value of the standard evaporation pressure interval, then the electronic expansion valve is controlled to decrease a second decreasing opening degree every third interval time length;

[0037] Or, in the case that the difference between the discharge pressure and the suction pressure is greater than or equal to the maximum value of the standard evaporation pressure interval, then the opening degree of the electronic expansion valve is kept unchanged.

[0038] In this way, through the above steps, the method can finely adjust the opening degree of the electronic expansion valve according to the difference between the suction pressure and the discharge pressure of the compressor while ensuring that the actual evaporation pressure is in the standard interval.

[0039] According to an embodiment of the present application, the step of controlling the electronic expansion valve of the unit to perform the PID adjustment phase specifically comprises:

[0040] Obtaining compressor current information, evaporation temperature information or suction superheat information of the unit;

[0041] According to the compressor current information, the evaporation temperature information or the suction superheat information, the opening degree of the electronic expansion valve is controlled to be adjusted.

[0042] In summary, through the above steps, the intelligent control strategy of the PID adjustment phase enables the system to dynamically adjust according to real-time data, adapt to different operating conditions and load changes, and ensure that the unit always operates in the best state.

[0043] According to an embodiment of the present application, the step of controlling the opening degree of the electronic expansion valve according to the compressor current information, the evaporation temperature information or the suction superheat information specifically comprises:

[0044] In the case that the compressor current is increased by at least a set current proportion every fourth interval, the opening of the electronic expansion valve is controlled to increase by a third rising opening.

[0045] In this way, through the control strategy based on the compressor current change, the water chiller can be timely adjusted when facing load changes, and the system efficiency and stability can be maintained.

[0046] According to an embodiment of the present application, the step of controlling the opening of the electronic expansion valve according to the compressor current information, the evaporating temperature information or the suction superheat information specifically comprises:

[0047] In the case that the evaporating temperature is less than or equal to a first evaporating temperature and continuously decreases, the opening of the electronic expansion valve is controlled to increase by a fourth rising opening every fifth interval;

[0048] Or, in the case that the evaporating temperature is greater than the first evaporating temperature and less than or equal to a second evaporating temperature, and the evaporating temperature decreases by a first decreasing temperature every fourth interval, the opening of the electronic expansion valve is controlled to increase by the fourth rising opening every fifth interval and continuously increase for a second set number of times;

[0049] Or, in the case that the evaporating temperature is greater than the second evaporating temperature and less than or equal to a third evaporating temperature, and the evaporating temperature decreases by a second decreasing temperature every fourth interval, the opening of the electronic expansion valve is controlled to increase by the fourth rising opening every fifth interval and continuously increase for a third set number of times;

[0050] Wherein, the first decreasing temperature is less than the second decreasing temperature, and the second set number of times is greater than the third set number of times.

[0051] In this way, through the control strategy based on the evaporating temperature change, the water chiller can be timely adjusted when facing different refrigeration demands and system states, and the system efficiency and stability can be maintained.

[0052] According to an embodiment of the present application, the step of controlling the opening of the electronic expansion valve according to the compressor current information, the evaporating temperature information or the suction superheat information specifically comprises:

[0053] According to the comparison result of the actual suction superheat and the target suction superheat, the opening of the electronic expansion valve is controlled to increase or decrease;

[0054] During the process that the opening of the electronic expansion valve increases or decreases, the cumulative change opening of the electronic expansion valve and the superheat change trend of the actual suction superheat are obtained, and the opening of the electronic expansion valve is adjusted in real time according to the cumulative change opening and the superheat change trend.

[0055] Thus, by the control strategy based on the comparison result of the actual suction superheat degree and the target suction superheat degree, the water chiller can be ensured to be adjusted in time under different operating conditions, and the high efficiency and stability of the system can be maintained.

[0056] The control device of the variable frequency screw water chiller according to the second aspect of the present application comprises:

[0057] The acquisition module is configured to determine that the compressor is started and stably operated, and then acquire an actual starting duration of the compressor in a starting stage.

[0058] The control module is configured to control an electronic expansion valve of the unit to perform a transition adjustment stage according to that the actual starting duration is less than the set starting duration, or control the electronic expansion valve of the unit to perform a PID adjustment stage according to that the actual starting duration is greater than or equal to the set starting duration.

[0059] The variable frequency screw water chiller according to the third aspect of the present application comprises a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor executes the program to realize the control method of the variable frequency screw water chiller according to the first aspect of the present application.

[0060] The present application provides a control method of a variable frequency screw water chiller, which adopts the parameters of refrigeration inlet water temperature, evaporation pressure, evaporation temperature, and suction superheat degree, adjusts the opening degree of the electronic expansion valve through the transition adjustment stage and the PID adjustment stage respectively, stably controls the change of the opening degree of the electronic expansion valve, responds to the demand of the compressor load change in time, and avoids the problem of too low suction and exhaust pressure difference.

[0061] Further, the control method of the present application has at least the following advantages compared with the related art: (1) Improving response speed: By introducing the transition stage adjustment and the suction superheat PID adjustment two stages, the present application can respond faster to the load changes of the compressor during startup and loading, and can establish the suction and exhaust pressure difference faster compared with the prior art, thereby improving the response speed and efficiency of the system. (2) Optimizing the startup process: The present application can more accurately control the compression process during the startup stage by monitoring the actual startup time of the compressor and determining the adjustment strategy of the electronic expansion valve according to the time, which can avoid the problems of system instability or low efficiency caused by long startup time. (3) Enhancing system stability: Through detailed transition adjustment and PID adjustment, the present application can effectively avoid the instability phenomenon of low suction pressure caused by improper control of the opening degree of the electronic expansion valve, thereby enhancing the stability of the entire water chiller under various working conditions. (4) Improving energy efficiency ratio: The present application can better match the load demand of the system by precisely controlling the opening degree of the electronic expansion valve, reduce energy waste, improve energy efficiency ratio, and achieve energy saving and emission reduction. (5) Enhancing adaptability: The control method of the present application can intelligently adjust according to the refrigeration inlet water temperature, evaporation pressure, evaporation temperature and suction superheat, etc. parameters, so that the action of the electronic expansion valve is more adaptive to the actual operating environment and conditions, improving the adaptability and reliability of the system. (6) Reducing maintenance cost: Since the present application can effectively reduce the system failures and downtime caused by improper control of the electronic expansion valve, the maintenance cost can be reduced and the service life of the equipment can be prolonged. BRIEF DESCRIPTION OF DRAWINGS

[0062] In order to more clearly illustrate the technical solutions in the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without any creative effort.

[0063] Figure 1 is a flowchart of the control method of the variable frequency screw water chiller provided by the present application;

[0064] Figure 2 is a structural schematic diagram of the control device of the variable frequency screw water chiller provided by the present application;

[0065] Figure 3 is a structural schematic diagram of the electronic device provided by the present application. DETAILED DESCRIPTION

[0066] In order to make the objects, technical solutions and advantages of the present application clearer, the following will be combined with the drawings in the present application to make a clear and complete description of the technical solutions in the present application. Obviously, the described embodiments are a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work belong to the protection scope of the present application.

[0067] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example" or "some examples" means that the specific features, structures, materials or characteristics described in combination with the embodiment or example are contained in at least one embodiment or example of the embodiments of the present application. In the present application, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in the present application and the features of the different embodiments or examples without contradiction.

[0068] The control method, control device and variable frequency screw water chiller of the present application are described below with reference to the accompanying drawings. Before the embodiments of the present application are described in detail, the entire application scenario is described. The control method, control device, electronic equipment and computer readable storage medium of the variable frequency screw water chiller of the embodiments of the present application can be applied to the local variable frequency screw water chiller, the cloud platform in the Internet field, or the cloud platform in other types of Internet fields, or can also be applied to third party equipment. The third party equipment can include mobile phones, tablet computers, notebook computers, vehicle-mounted computers and other smart terminals of various types.

[0069] The control method of the present application is described below only as an example applicable to the variable frequency screw water chiller. It should be understood that the control method of the embodiments of the present application can also be applicable to the cloud platform and the third party equipment.

[0070] As shown in Figure 1 The control method of the variable frequency screw water chiller according to the first embodiment of the present application comprises:

[0071] Step S1, determining that the compressor is started and stably operated, then acquiring the actual starting time length spent by the compressor in the starting stage;

[0072] Step S2, according to the actual start-up duration is less than the set start-up duration, then the electronic expansion valve of the unit is controlled to perform a transition adjustment phase; or, according to the actual start-up duration is greater than or equal to the set start-up duration, then the electronic expansion valve of the unit is controlled to perform a PID adjustment phase.

[0073] The specific working principle and working process of the control method of the variable frequency screw water chiller according to the embodiment of the application are as follows: in step S1, the system first needs to determine whether the compressor has started and reached a stable running state. Once it is confirmed that the compressor has started, the system will record and obtain the time taken by the compressor from starting to stable running, i.e. the actual start-up duration. This time is an important parameter for evaluating the state of the compressor and making subsequent control judgments.

[0074] Further, step S2 is the core of the control method, and the system will compare the actual start-up duration with the preset set start-up duration to determine which adjustment phase the electronic expansion valve should perform:

[0075] If the actual start-up duration is less than the set start-up duration: this means that the starting process of the compressor is faster, and more detailed adjustment may be needed to ensure smooth transition of the system. In this case, the system will control the electronic expansion valve to perform a transition adjustment phase. In the transition adjustment phase, the opening degree of the electronic expansion valve will be adjusted according to a series of preset conditions and parameters to adapt to the rapid start of the compressor and load changes, preventing possible low suction pressure or other unstable conditions.

[0076] If the actual start-up duration is greater than or equal to the set start-up duration: this indicates that the starting process of the compressor has been completed, and the system needs to enter a more stable running state. At this time, the system will control the electronic expansion valve to perform a PID adjustment phase. In the PID adjustment phase, the opening degree of the electronic expansion valve will be dynamically adjusted according to the proportional-integral-derivative (PID) control algorithm to maintain stable operation of the system and respond to external load changes in a timely manner.

[0077] The set start-up duration can be 300 seconds, of course, the specific value of the set start-up duration is not limited to this, and the set start-up duration can be determined according to specific circumstances.

[0078] In summary, through these two steps, the control method of the application can intelligently adjust the opening degree of the electronic expansion valve according to the actual start and running of the compressor, thereby improving the running efficiency and stability of the entire water chiller. This method not only adapts to different starting conditions, but also responds to load changes in a timely manner during the operation of the unit, ensuring stable and efficient operation of the unit.

[0079] In the related art, during the starting stage of the variable frequency screw water chiller unit, different chilled water inlet temperatures result in different refrigerant pressures and evaporation temperatures, thus requiring higher action adjustment of the electronic expansion valve. The existing control method generally adjusts the opening degree of the electronic expansion valve through suction superheat degree or discharge superheat degree PID. This method has the problems of inaccurate calculation, low suction pressure alarm caused by too small opening degree of the electronic expansion valve, slow establishment of suction and discharge pressure difference, and untimely action of the electronic expansion valve during the starting stage of the compressor and when the chilled water inlet temperature is low, thus failing to respond to the demand for load change of the compressor in time.

[0080] Therefore, in order to solve the technical defects in the related art, the present application provides a control method for a variable frequency screw water chiller unit, which uses the parameters of chilled water inlet temperature, evaporation pressure, evaporation temperature, and suction superheat degree to adjust the opening degree of the electronic expansion valve through a transition adjustment stage and a PID adjustment stage, to stably control the change of the opening degree of the electronic expansion valve, to respond to the demand for load change of the compressor in time, and to avoid the problem of too low suction and discharge pressure difference.

[0081] Further, the control method of the present application has at least the following advantages compared with the related art: (1) improved response speed: by introducing the transition stage adjustment and the suction superheat degree PID adjustment stages, the present application can respond to the load change of the compressor during the starting and loading processes more quickly, compared with the prior art, the suction and discharge pressure difference can be established more quickly, thus improving the response speed and efficiency of the system. (2) optimized starting process: the present application can more accurately control the compression process during the starting stage by monitoring the actual starting time of the compressor and determining the adjustment strategy of the electronic expansion valve according to the time, thus avoiding the problems of system instability or low efficiency caused by long starting time. (3) enhanced system stability: through detailed transition adjustment and PID adjustment, the present application can effectively avoid the phenomenon of too low suction pressure caused by improper control of the opening degree of the electronic expansion valve, thus enhancing the stability of the entire water chiller unit under various working conditions. (4) improved energy efficiency ratio: the present application can better match the load demand of the system by accurately controlling the opening degree of the electronic expansion valve, reduce energy waste, improve the energy efficiency ratio, and achieve energy saving and emission reduction. (5) enhanced adaptability: the control method of the present application can intelligently adjust according to the parameters of chilled water inlet temperature, evaporation pressure, evaporation temperature, and suction superheat degree, making the action of the electronic expansion valve more adaptive to the actual operating environment and conditions, improving the adaptability and reliability of the system. (6) reduced maintenance cost: since the present application can effectively reduce system failures and downtime caused by improper control of the electronic expansion valve, the maintenance cost can be reduced and the service life of the equipment can be prolonged.

[0082] For the convenience of description, the specific control details of the transition adjustment phase and the PID adjustment phase of the electronic expansion valve of the unit will be introduced in turn below.

[0083] For the transition adjustment phase, according to some embodiments of the present application, the steps of controlling the electronic expansion valve of the unit to perform the transition adjustment phase specifically include:

[0084] Obtaining the current descending rate of the evaporating pressure of the unit;

[0085] In the case where the current descending rate is greater than the first set rate, obtaining the last descending rate of the evaporating pressure of the unit, and controlling the opening of the electronic expansion valve according to the last descending rate;

[0086] Or, in the case where the current descending rate is less than or equal to the first set rate, obtaining the chilled water inlet temperature, and controlling the opening of the electronic expansion valve according to the chilled water inlet temperature.

[0087] In this embodiment, at the beginning of the transition adjustment phase, the system first needs to monitor and record the change of the evaporating pressure of the unit at the current time, i.e., the current descending rate. The descending rate of the evaporating pressure is a key parameter for evaluating the change of the compressor load and the response of the system.

[0088] Subsequently, the system further judges the relationship between the current descending rate and the first set rate:

[0089] If the current descending rate is greater than the first set rate: this indicates that the evaporating pressure is descending at a relatively fast speed, which may mean that the system needs more refrigerant flow to meet the load demand. In this case, the system will obtain the last descending rate of the evaporating pressure, and adjust the opening of the electronic expansion valve according to this historical data. This adjustment strategy based on historical data helps to smooth the change of the evaporating pressure, preventing the system from being unstable due to the too fast descending of the pressure.

[0090] If the current descending rate is less than or equal to the first set rate: this indicates that the evaporating pressure is descending at an acceptable speed, and the system can adjust the opening of the electronic expansion valve according to the current chilled water inlet temperature. The chilled water inlet temperature is an important factor affecting the refrigeration effect, and by adjusting the opening of the electronic expansion valve, the flow of refrigerant can be controlled, so as to maintain the operating efficiency and stability of the water chiller.

[0091] It can be understood that whether based on the last descending rate or the chilled water inlet temperature, the ultimate goal is to accurately control the opening of the electronic expansion valve to adapt to the current system operating state and load demand.

[0092] In this way, the method can provide more accurate and intelligent electronic expansion valve control strategies during the startup and transition phases of the water chiller, thereby improving system stability and efficiency, reducing energy waste, and enhancing overall performance. This method can adapt to different operating conditions and load changes, ensuring that the water chiller always operates in the best state.

[0093] In some embodiments of the present application, if the current descent rate is greater than the first set rate, the step of adjusting the opening of the electronic expansion valve according to the last descent rate specifically includes:

[0094] In the case where the last descent rate is greater than the first set rate and greater than or equal to the second set rate, or the last descent rate is greater than or equal to the first set rate and greater than the second set rate, the electronic expansion valve is controlled to increase the first opening rate every first interval and continuously for the first set number of times, then maintain the current opening for a set duration.

[0095] In the case where the last descent rate is less than or equal to the first set rate or less than the second set rate, or the last descent rate is less than the first set rate or less than or equal to the second set rate, the refrigeration inlet water temperature of the unit is obtained, and the opening of the electronic expansion valve is adjusted according to the refrigeration inlet water temperature.

[0096] In this embodiment, first, the system will check whether the last descent rate of the evaporation pressure meets one of the following two conditions: the last descent rate is greater than the first set rate (e.g. 0.002 Mpa / s) and greater than or equal to the second set rate (e.g. 0.003 Mpa / s); the last descent rate is greater than or equal to the first set rate and greater than the second set rate. It can be understood that these two conditions are evaluations of the last evaporation pressure descent rate to determine whether the system needs to take emergency measures to adjust the opening of the electronic expansion valve.

[0097] If the last descent rate meets any of the above conditions, the system will perform the following operations: every first interval, the opening of the electronic expansion valve will increase by the first opening rate; this process will be continuously performed for the first set number of times; after completing the continuous increase operation, the electronic expansion valve will maintain the current opening for a set duration. It can be understood that the purpose of the above operation is to quickly respond to the rapid descent of the evaporation pressure, and to increase the flow of refrigerant by gradually increasing the opening of the electronic expansion valve, thereby stabilizing the system pressure and preventing the suction pressure from being too low.

[0098] If the last drop rate does not meet the above conditions, i.e., the last drop rate is less than or equal to the first set rate or less than the second set rate, the system will instead obtain the chilled water inlet temperature of the unit. Further, the system will control the opening degree of the electronic expansion valve according to the obtained chilled water inlet temperature. It can be understood that the chilled water inlet temperature is an important factor affecting the performance of the water chiller, and by adjusting the opening degree of the electronic expansion valve, the flow rate of the refrigerant can be optimized to adapt to the current heat load and operating conditions.

[0099] In this way, through these detailed control steps, the present application can ensure that the opening degree of the electronic expansion valve is timely and appropriately adjusted in the case of a rapid evaporation pressure drop rate, thereby maintaining the stability and efficiency of the water chiller. This method improves the adaptability and reliability of the system, reduces potential problems caused by rapid pressure changes, and also optimizes energy efficiency and performance.

[0100] In some specific embodiments of the present application, in the case where the current drop rate is less than or equal to the first set rate, the step of controlling the opening degree of the electronic expansion valve according to the chilled water inlet temperature specifically includes:

[0101] Obtaining the actual evaporation pressure of the unit;

[0102] Determining a standard evaporation pressure interval of the unit according to the interval in which the chilled water inlet temperature falls;

[0103] Controlling the opening degree of the electronic expansion valve according to the comparison result of the actual evaporation pressure and the standard evaporation pressure interval.

[0104] In this embodiment, the system first needs to monitor and record the current actual evaporation pressure value of the unit in real time, which is the basic data for subsequent adjustment and judgment. Next, the system will refer to the pre-set corresponding relationship between the standard evaporation pressure and the chilled water inlet temperature according to the measured value of the current chilled water inlet temperature, and determine a standard evaporation pressure interval, which is based on ideal working conditions and design parameters, and is used to evaluate whether the actual operating state is normal.

[0105] After that, the system compares the actual evaporation pressure with the standard evaporation pressure interval to determine whether the current operating state meets the expectations. If the actual evaporation pressure is lower than the standard interval, it may mean that the system needs more refrigerant flow to meet the load demand; if the actual evaporation pressure is higher than the standard interval, it may need to reduce the flow to avoid excessive compression or reduce energy efficiency.

[0106] Finally, based on the comparison results of the actual evaporation pressure and the standard evaporation pressure interval, the system will adjust the opening of the electronic expansion valve. If the refrigerant flow needs to be increased, the opening of the electronic expansion valve will be increased; if the flow needs to be reduced, the opening of the electronic expansion valve will be reduced. This adjustment is dynamic and can be fine-tuned in real time to ensure that the chiller unit operates efficiently and stably under various working conditions.

[0107] In this way, through the above steps, the present application can realize accurate control of the opening of the electronic expansion valve, thereby optimizing the performance and energy efficiency of the chiller unit. This method improves the adaptability and reliability of the system through real-time monitoring and intelligent adjustment, ensuring that the unit maintains the best operating state under different working conditions.

[0108] Further, the step of determining the standard evaporation pressure interval of the unit according to the interval of the chilled water inlet temperature comprises:

[0109] When the chilled water inlet temperature is in the first temperature interval, the standard evaporation pressure interval is the first pressure interval;

[0110] When the chilled water inlet temperature is in the second temperature interval, the standard evaporation pressure interval is the second pressure interval;

[0111] When the chilled water inlet temperature is in the third temperature interval, the standard evaporation pressure interval is the third pressure interval;

[0112] When the chilled water inlet temperature is in the fourth temperature interval, the standard evaporation pressure interval is the fourth pressure interval;

[0113] Wherein, the arrangement order of each temperature interval of the chilled water inlet temperature from large to small is: the fourth temperature interval, the third temperature interval, the second temperature interval, the first temperature interval; the arrangement order of the maximum value of each standard evaporation pressure interval from large to small is: the maximum value of the fourth pressure interval, the maximum value of the third pressure interval, the maximum value of the second pressure interval, the maximum value of the first pressure interval; the arrangement order of the minimum value of each standard evaporation pressure interval from large to small is: the minimum value of the fourth pressure interval, the minimum value of the third pressure interval, the minimum value of the second pressure interval, the minimum value of the first pressure interval.

[0114] For example, when the chilled water inlet temperature is less than 5℃, the standard pressure interval is 0.26Mpa to 0.22Mpa; when the chilled water inlet temperature is less than or equal to 12℃ and greater than or equal to 5℃, the standard pressure interval is 0.27Mpa to 0.23Mpa; when the chilled water inlet temperature is less than or equal to 20℃ and greater than 12℃, the standard pressure interval is 0.28Mpa to 0.24Mpa; when the chilled water inlet temperature is greater than 20℃, the standard pressure interval is 0.29Mpa to 0.25Mpa.

[0115] Further, according to the comparison result of the actual evaporation pressure and the standard evaporation pressure interval, the step of controlling the opening degree of the electronic expansion valve specifically includes:

[0116] In the case where the actual evaporation pressure is not in the standard evaporation pressure interval, the opening degree of the electronic expansion valve is increased or decreased according to the comparison result;

[0117] Or, in the case where the actual evaporation pressure is in the standard evaporation pressure interval, the suction pressure and discharge pressure of the compressor are obtained, and the opening degree of the electronic expansion valve is controlled according to the suction pressure and discharge pressure.

[0118] In this embodiment, the system first compares the actually measured evaporation pressure with the pre-determined standard evaporation pressure interval. This comparison is to assess whether the current operating state is within the ideal or expected range.

[0119] Subsequently, the system adjusts the opening degree of the electronic expansion valve according to the comparison result:

[0120] If the actual evaporation pressure is not in the standard evaporation pressure interval, it means that the current system operating state deviates from the expected ideal state. In this case, the system will decide whether to increase or decrease the opening degree of the electronic expansion valve according to the gap between the actual evaporation pressure and the standard interval. For example, if the actual evaporation pressure is lower than the standard interval, the system may increase the opening degree of the electronic expansion valve to increase the refrigerant flow, thereby increasing the evaporation pressure; conversely, if the actual evaporation pressure is higher than the standard interval, the system may decrease the opening degree of the electronic expansion valve to reduce the refrigerant flow, thereby reducing excessive compression and improving energy efficiency.

[0121] If the actual evaporation pressure is in the standard evaporation pressure interval, it means that the system operating state is good, and the evaporation pressure meets the expectations. In this case, the system will further obtain the suction pressure and discharge pressure of the compressor for more detailed adjustment. For example, if the suction pressure is too low, it may indicate that the refrigerant flow needs to be increased to avoid backflow; if the discharge pressure is too high, it may indicate that the flow needs to be reduced to avoid excessive compression and overheating. In this way, the system can more accurately control the opening degree of the electronic expansion valve to maintain the optimal operating state of the compressor and the entire chiller unit.

[0122] In this way, through the above detailed control steps, the present application can ensure that the opening degree of the electronic expansion valve is accurately and reasonably adjusted, thereby optimizing the performance and energy efficiency of the chiller unit. This method improves the adaptability and reliability of the system by real-time monitoring and intelligent adjustment, ensuring that the unit can maintain the best operating state under different working conditions.

[0123] In some embodiments, when the actual evaporation pressure is not in the standard evaporation pressure interval, the step of increasing or decreasing the opening of the electronic expansion valve according to the comparison result specifically includes:

[0124] In the case where the actual evaporation pressure exceeds the standard evaporation pressure interval, the electronic expansion valve is controlled to decrease the first decreasing opening every second interval time length;

[0125] Or, in the case where the evaporation pressure is lower than the standard evaporation pressure interval, the electronic expansion valve is controlled to increase the second increasing opening every second interval time length.

[0126] In this embodiment, when the actual evaporation pressure is higher than the standard evaporation pressure interval, it may indicate that the system has the risk of excessive compression or efficiency reduction. In order to reduce the evaporation pressure, the system will control the electronic expansion valve to decrease the first decreasing opening every second interval time length. This opening decreasing operation will reduce the refrigerant flow to the evaporator, thereby reducing the evaporation pressure to return it to the standard interval, ensuring the stable operation and efficiency of the system.

[0127] And if the actual evaporation pressure is lower than the standard interval, it may mean that the system refrigerant flow is insufficient to meet the current cooling load demand. In order to increase the evaporation pressure, the system will control the electronic expansion valve to increase the second increasing opening every second interval time length. This opening increasing operation will increase the refrigerant flow to the evaporator, thereby increasing the evaporation pressure to reach or approach the standard interval to meet the cooling load demand and maintain the high efficiency of the system.

[0128] For example, when the actual evaporation pressure exceeds the standard evaporation pressure interval, the electronic expansion valve is controlled to decrease the opening by 1% every 2 seconds; when the evaporation pressure is lower than the standard evaporation pressure interval, the electronic expansion valve is controlled to increase the opening by 1% every 2 seconds.

[0129] In this way, the method can intelligently adjust the opening of the electronic expansion valve according to the actual operating conditions to maintain the evaporation pressure within the ideal standard interval. This method not only improves the operating efficiency and stability of the water chiller, but also dynamically adjusts according to the actual load changes and system requirements to optimize energy efficiency and performance.

[0130] In other embodiments, when the actual evaporation pressure is in the standard evaporation pressure interval, the step of controlling the opening of the electronic expansion valve according to the suction pressure and the discharge pressure specifically includes:

[0131] In the case where the difference between the discharge pressure and the suction pressure is less than the maximum value of the standard evaporation pressure interval, the electronic expansion valve is controlled to decrease the second decreasing opening every third interval time length;

[0132] Alternatively, in the case where the difference between the exhaust pressure and the suction pressure is greater than or equal to the maximum value of the standard evaporation pressure range, the electronic expansion valve opening degree is kept unchanged.

[0133] In the present embodiment, the system first calculates the difference between the currently measured exhaust pressure and suction pressure, which reflects the working pressure of the compressor and the operating state of the system. Subsequently, the system determines the relationship between the difference and the maximum value of the standard evaporation pressure range:

[0134] If the difference between the exhaust pressure and the suction pressure is less than the maximum value of the standard evaporation pressure range, it may mean that the working pressure of the system is low, and there is room for further increasing the refrigerant flow. In order to improve the refrigeration effect of the system, the system will control the electronic expansion valve to decrease the second decreasing opening degree every third interval time. This operation will cause the opening degree of the electronic expansion valve to decrease slightly, thereby finely adjusting the flow of refrigerant and optimizing the operating efficiency of the system.

[0135] If the difference between the exhaust pressure and the suction pressure is greater than or equal to the maximum value of the standard evaporation pressure range, it indicates that the working pressure of the system has reached or exceeded the expected maximum value, and the operating state of the system is reasonable and does not need to be further adjusted. In this case, the system will keep the opening degree of the electronic expansion valve unchanged to maintain the current operating state and performance.

[0136] For example, if the difference between the exhaust pressure and the suction pressure is less than the maximum value of the standard evaporation pressure range, the electronic expansion valve is controlled to decrease the opening degree by 1% every 10 seconds; if the difference between the exhaust pressure and the suction pressure is greater than or equal to the maximum value of the standard evaporation pressure range, the opening degree of the electronic expansion valve is unchanged.

[0137] In this way, through the above steps, the present method can finely adjust the opening degree of the electronic expansion valve according to the difference between the suction and exhaust pressures of the compressor while ensuring that the actual evaporation pressure is within the standard range.

[0138] The specific control details of the electronic expansion valve executing the PID regulation phase are described below.

[0139] For the PID regulation phase, according to some embodiments of the present application, the steps of controlling the electronic expansion valve of the unit to execute the PID regulation phase specifically include:

[0140] Obtaining compressor current information, evaporation temperature information, or suction superheat degree information of the unit;

[0141] Controlling the opening degree of the electronic expansion valve according to the compressor current information, evaporation temperature information, or suction superheat degree information.

[0142] In this embodiment, the system first needs to obtain the compressor current information, evaporating temperature information, or suction superheat information of the unit in real time.

[0143] Among them, the compressor current information reflects the load and running strength of the compressor, and the increase of current generally indicates that the compressor is handling greater load or refrigeration demand. The evaporating temperature information refers to the temperature of the refrigerant in the evaporator, which is closely related to the refrigeration efficiency and system performance. The suction superheat information represents the degree to which the temperature of the refrigerant sucked by the compressor is higher than its saturation temperature, which affects the running efficiency of the compressor and the stability of the system.

[0144] According to the obtained compressor current information, evaporating temperature information, or suction superheat information, the system will dynamically adjust the opening degree of the electronic expansion valve.

[0145] For example, if the compressor current increases, indicating that the load increases, more refrigerant flow may be needed to meet the demand. At this time, the system can appropriately increase the opening degree of the electronic expansion valve to increase the refrigerant flow to the evaporator.

[0146] For another example, if the evaporating temperature is too low or continues to drop, it may mean that the opening degree of the electronic expansion valve is too small, causing the compressor to load too quickly or the refrigerant flow to be insufficient. The system can increase the opening degree of the electronic expansion valve to quickly adjust to the appropriate range.

[0147] For another example, if the suction superheat deviates from the target value, the system will adjust the opening degree of the electronic expansion valve according to the direction and size of the deviation to make the suction superheat return to the target range, ensuring the efficient operation of the system.

[0148] In summary, through the above steps, the intelligent control strategy of the PID adjustment stage enables the system to dynamically adjust according to real-time data, adapt to different operating conditions and load changes, and ensure that the unit always operates in the best state.

[0149] In some specific embodiments of the present application, the step of controlling the opening degree of the electronic expansion valve according to the compressor current information, evaporating temperature information, or suction superheat information specifically includes:

[0150] In the case where the compressor current increases by at least a set current proportion every fourth interval length, the opening degree of the electronic expansion valve is controlled to increase by a third rising opening degree.

[0151] In this embodiment, the function logic here is to prevent the compressor from loading too quickly, and the electronic expansion valve adjustment cannot meet the demand of rapid loading. By the change of current, the change of compressor loading rate can be well reflected, so the change of current is used to judge whether the valve opening degree needs to be increased.

[0152] For example, when the compressor current increases by 15% every 10 seconds, then the control electronic expansion valve is controlled to increase the opening degree by 5% of the original opening degree.

[0153] In this way, through this control strategy based on the compressor current change, the application can ensure that the water chiller can be adjusted in time when facing load changes, and maintain the high efficiency and stability of the system.

[0154] In some embodiments of the application, the step of controlling the opening degree of the electronic expansion valve according to the compressor current information, the evaporating temperature information or the suction superheat information specifically comprises:

[0155] In the case where the evaporating temperature is less than or equal to the first evaporating temperature and continues to decrease, the electronic expansion valve is controlled to increase the fourth opening degree every fifth interval.

[0156] It can be understood that since the evaporating temperature is already less than the first evaporating temperature required by the system and continues to decrease, it indicates that the compressor is loaded too fast or the opening degree of the electronic expansion valve is too small at this time, so the electronic expansion valve needs to be quickly opened to a suitable range.

[0157] Alternatively, in the case where the evaporating temperature is greater than the first evaporating temperature and less than or equal to the second evaporating temperature, and the evaporating temperature decreases by the first decreasing temperature every fourth interval, the electronic expansion valve is controlled to increase the fourth opening degree every fifth interval and continuously increase for the second set number of times.

[0158] It can be understood that since the evaporating temperature is already less than the second evaporating temperature required by the system and continues to decrease, it indicates that the compressor is loaded too fast or the opening degree of the electronic expansion valve is too small, and the electronic expansion valve needs to be quickly opened to a suitable range at this time. The evaporating temperature is still acceptable and has not reached the first evaporating temperature, so it is not necessary to continuously act.

[0159] Alternatively, in the case where the evaporating temperature is greater than the second evaporating temperature and less than or equal to the third evaporating temperature, and the evaporating temperature decreases by the second decreasing temperature every fourth interval, the electronic expansion valve is controlled to increase the fourth opening degree every fifth interval and continuously increase for the third set number of times.

[0160] It can be understood that the evaporating temperature is already less than the third evaporating temperature required by the system and continues to decrease, which indicates that the compressor is loaded too fast or the opening degree of the electronic expansion valve is too small, and the electronic expansion valve needs to be quickly opened to a suitable range at this time. The evaporating temperature is still acceptable and has not reached the first evaporating temperature, so it is not necessary to continuously act.

[0161] The first temperature drop is less than the second temperature drop, and the second set number is greater than the third set number. It can be understood that in the above control strategy, the first temperature drop is less than the second temperature drop, which reflects the sensitivity of the system to the speed of temperature drop at different temperatures. At the same time, the second set number is greater than the third set number, which means that the system responds more actively to the second evaporation temperature interval.

[0162] For example, if the evaporation temperature is ≤0℃ and continues to drop, the electronic expansion valve is opened by 2% every 3 seconds; if 0℃<evaporation temperature≤4℃ and the evaporation temperature drops by 1℃ every 10 seconds, the electronic expansion valve is opened by 2% every 3 seconds and acts continuously for 3 times; if 4℃<evaporation temperature≤8℃ and the evaporation temperature drops by 2℃ every 10 seconds, the electronic expansion valve is opened by 2% every 3 seconds and acts continuously for 2 times.

[0163] In this way, through these control strategies based on the change of the evaporation temperature, the application can ensure that the water chiller can be adjusted in time when facing different refrigeration demands and system states, and maintain the high efficiency and stability of the system.

[0164] In still some specific embodiments of the application, the step of controlling the opening degree of the electronic expansion valve according to the compressor current information, the evaporation temperature information or the suction superheat information specifically comprises:

[0165] According to the comparison result of the actual suction superheat and the target suction superheat, the opening degree of the electronic expansion valve is controlled to increase or decrease;

[0166] In the process of increasing or decreasing the opening degree of the electronic expansion valve, the cumulative change opening degree of the electronic expansion valve and the superheat change trend of the actual suction superheat are obtained, and the opening degree of the electronic expansion valve is adjusted in real time according to the cumulative change opening degree and the superheat change trend.

[0167] In this embodiment, the system continuously monitors the actual suction superheat of the compressor and compares it with the preset target suction superheat:

[0168] If the actual suction superheat is higher than the target suction superheat, it may mean that the system needs more refrigerant flow to reduce the suction temperature. In this case, the system will control the opening degree of the electronic expansion valve to increase, so as to increase the refrigerant flow to the evaporator, thereby reducing the suction superheat and making it close to the target value.

[0169] If the actual suction superheat is lower than the target suction superheat, it may mean that the system has excessive refrigerant flow or insufficient load. At this time, the system will control the opening degree of the electronic expansion valve to decrease, so as to reduce the refrigerant flow and prevent excessive refrigeration and energy loss.

[0170] In addition, during the adjustment of the electronic expansion valve opening, the system obtains the cumulative change opening of the electronic expansion valve and the change trend of the actual suction superheat degree. The cumulative change opening refers to the total change amount of the electronic expansion valve opening from the initial state to the present, and the change trend of the superheat degree refers to the change direction and speed of the suction superheat degree over time.

[0171] According to the cumulative change opening and the change trend of the superheat degree, the system will adjust the opening of the electronic expansion valve in real time: if the cumulative change opening is large or the change trend of the superheat degree shows that the current adjustment direction has lasted for a period of time, the system may reduce the adjustment amplitude or suspend the adjustment to avoid system instability caused by excessive adjustment; if the cumulative change opening is small and the change trend of the superheat degree shows that further adjustment is needed, the system will continue to increase or decrease the opening of the electronic expansion valve to more accurately control the suction superheat degree.

[0172] In this way, through this control strategy based on the comparison result of the actual suction superheat degree and the target suction superheat degree, the application can ensure that the water chiller can be adjusted in time when facing different operating conditions, and maintain the high efficiency and stability of the system.

[0173] For example, compare the current suction superheat degree and the target suction superheat degree. If the current suction superheat degree is less than the target suction superheat degree, and the suction superheat degree has an upward trend after the valve is closed, the electronic expansion valve maintains the current opening. In this way, since the electronic expansion valve is closed small and the suction superheat degree has an upward trend, it means that the action of closing the valve works at this time, so the current opening needs to be maintained and observed for a period of time.

[0174] If the cumulative closing is greater than or equal to 5% of the maximum opening of the electronic expansion valve, the electronic expansion valve maintains the current opening for 30 seconds; otherwise, the PID control reduces the opening of the electronic expansion valve. In this way, it can prevent the electronic expansion valve from being closed too large in one time, and avoid the rapid reduction of evaporation pressure.

[0175] For example, compare the current suction superheat degree and the target suction superheat degree. If the current suction superheat degree is greater than the target suction superheat degree, and the suction superheat degree has a downward trend after the valve is opened, the electronic expansion valve maintains the current opening. In this way, since the electronic expansion valve is opened small and the suction superheat degree has a downward trend, it means that the action of opening the valve works at this time, so the current opening needs to be maintained and observed for a period of time.

[0176] If the cumulative opening is greater than or equal to 5% of the maximum opening of the electronic expansion valve, the electronic expansion valve maintains the current opening for 30 seconds; otherwise, the PID control increases the opening of the electronic expansion valve. In this way, it can prevent the electronic expansion valve from being opened too large in one time, and avoid the liquid suction of the compressor.

[0177] For another example, the current suction superheat degree and the target suction superheat degree are compared, and if the current suction superheat degree is equal to the target suction superheat degree, the electronic expansion valve keeps the current opening degree. It can be understood that, since the suction superheat degree has been equal to the target value, it indicates that the opening degree of the electronic expansion valve at this time is the optimal opening degree, and thus no adjustment is needed.

[0178] The control device of the variable frequency screw water chiller provided by the application is described below, and the control device of the variable frequency screw water chiller described below can be correspondingly referred to the control method of the variable frequency screw water chiller described above.

[0179] As shown in Figure 2 The control device of the variable frequency screw water chiller according to the second aspect embodiment of the application comprises:

[0180] The acquisition module 110 is configured to determine that the compressor is started and stably operated, and then acquire an actual starting duration of the compressor in a starting stage.

[0181] The control module 120 is configured to control the electronic expansion valve of the unit to perform a transition adjustment stage according to that the actual starting duration is less than the set starting duration, or control the electronic expansion valve of the unit to perform a PID adjustment stage according to that the actual starting duration is greater than or equal to the set starting duration.

[0182] The variable frequency screw water chiller according to the third aspect embodiment of the application comprises a memory, a processor and a computer program stored in the memory and executable on the processor, and the processor implements the control method of the variable frequency screw water chiller according to the first aspect embodiment of the application when executing the program.

[0183] Figure 3 An example of a schematic diagram of a physical structure of an electronic device is shown in Figure 3 The electronic device can comprise a processor 810, a communications interface 820, a memory 830 and a communications bus 840, wherein the processor 810, the communications interface 820 and the memory 830 complete communications with each other through the communications bus 840. The processor 810 can invoke a logical instruction in the memory 830 to execute the control method of the variable frequency screw water chiller, comprising: determining that the compressor is started and stably operated, and then acquiring an actual starting duration of the compressor in a starting stage; controlling the electronic expansion valve of the unit to perform a transition adjustment stage according to that the actual starting duration is less than the set starting duration, or controlling the electronic expansion valve of the unit to perform a PID adjustment stage according to that the actual starting duration is greater than or equal to the set starting duration.

[0184] In addition, the logic instructions in the memory 830 described above can be implemented in the form of software function units and sold or used as independent products, and can be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the present application essentially or the parts that contribute to the prior art or parts of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium, and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the embodiments of the method of the present application. The aforementioned storage medium includes: a U disk, 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 disk, and various media that can store program codes.

[0185] In another aspect, the present application also provides a computer program product, the computer program product comprising a computer program, the computer program being stored in a non-transitory computer readable storage medium, and the computer program being executable by a processor to cause a computer to perform the control method of the variable frequency screw chiller unit provided by the above-mentioned methods, comprising: determining that the compressor is started and stably operated, then obtaining an actual starting duration spent by the compressor in a starting phase; according to that the actual starting duration is less than a set starting duration, controlling the electronic expansion valve of the unit to perform a transition adjustment phase; or, according to that the actual starting duration is greater than or equal to the set starting duration, controlling the electronic expansion valve of the unit to perform a PID adjustment phase.

[0186] In another aspect, the present application also provides a computer program product, the computer program product comprising a computer program, the computer program being stored in a non-transitory computer readable storage medium, and the computer program being executable by a processor to cause a computer to perform the control method of the variable frequency screw chiller unit provided by the above-mentioned methods, comprising: determining that the compressor is started and stably operated, then obtaining an actual starting duration spent by the compressor in a starting phase; according to that the actual starting duration is less than a set starting duration, controlling the electronic expansion valve of the unit to perform a transition adjustment phase; or, according to that the actual starting duration is greater than or equal to the set starting duration, controlling the electronic expansion valve of the unit to perform a PID adjustment phase.

[0187] The device embodiments described above are only schematic, and the units shown as separate components can or can not be physically separate, and the components shown as units can or can not be physical units, i.e. they can be located in one place, or distributed on multiple network units. Part or all of the modules can be selected according to actual needs to achieve the purpose of the present embodiment. Those skilled in the art can understand and implement without creative labor.

[0188] Those skilled in the art can clearly understand the technical solutions of the various embodiments from the above description of the embodiments, and the various embodiments can be implemented by means of software with the necessary general hardware platforms, and of course can also be implemented by hardware. Based on such understanding, the above technical solutions, essentially or in other words, the part of the prior art that makes a contribution, can be embodied in the form of a software product, which can be stored in a computer readable storage medium, such as a ROM / RAM, a magnetic disk, an optical disk, and the like, and includes a number of instructions to make a computer device (which can be a personal computer, a server, or a network device, etc.) execute the methods of the various embodiments or some parts of the embodiments.

[0189] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, rather than limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for some technical features therein; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A control method of a variable frequency screw water chiller, characterized in that, The method comprises the steps of: determining that the compressor is started and stably operated, and then obtaining an actual starting time length consumed by the compressor in a starting stage; controlling an electronic expansion valve of the unit to perform a transition adjustment stage according to that the actual starting time length is less than a set starting time length; or controlling the electronic expansion valve of the unit to perform a PID adjustment stage according to that the actual starting time length is greater than or equal to the set starting time length.

2. The control method of the variable frequency screw water chiller according to claim 1, characterized in that, The step of controlling the electronic expansion valve of the unit to perform the transition adjustment stage specifically comprises the steps of: obtaining a current descending rate of evaporating pressure of the unit; in a case where the current descending rate is greater than a first set rate, obtaining a previous descending rate of evaporating pressure of the unit, and controlling the opening degree of the electronic expansion valve according to the previous descending rate; or, in a case where the current descending rate is less than or equal to the first set rate, obtaining a chilled water inlet temperature of the unit, and controlling the opening degree of the electronic expansion valve according to the chilled water inlet temperature.

3. The control method of the variable frequency screw water chiller according to claim 2, characterized in that, In the case where the current descending rate is greater than the first set rate, the step of controlling the opening degree of the electronic expansion valve according to the previous descending rate specifically comprises the steps of: in a case where the previous descending rate is greater than the first set rate and greater than or equal to a second set rate, or the previous descending rate is greater than or equal to the first set rate and greater than the second set rate, controlling the electronic expansion valve to increase a first increasing opening degree every first interval time length and continuously increase the first increasing opening degree for a first set number of times, and then maintaining the current opening degree for a set time length; in a case where the previous descending rate is less than or equal to the first set rate or less than the second set rate, or the previous descending rate is less than the first set rate or less than or equal to the second set rate, obtaining the chilled water inlet temperature of the unit, and controlling the opening degree of the electronic expansion valve according to the chilled water inlet temperature.

4. The control method of the variable frequency screw water chiller according to claim 2, characterized in that, In the case where the current descending rate is less than or equal to the first set rate, the step of controlling the opening degree of the electronic expansion valve according to the chilled water inlet temperature specifically comprises the steps of: obtaining an actual evaporating pressure of the unit; determining a standard evaporating pressure interval of the unit according to the interval in which the chilled water inlet temperature is located; controlling the opening degree of the electronic expansion valve according to a comparison result of the actual evaporating pressure and the standard evaporating pressure interval.

5. The control method of the variable frequency screw water chiller according to claim 4, characterized in that, The step of determining the standard evaporating pressure interval of the unit according to the interval in which the chilled water inlet temperature is located specifically comprises the steps of: in a case where the chilled water inlet temperature is located in a first temperature interval, the standard evaporating pressure interval is a first pressure interval; in a case where the chilled water inlet temperature is located in a second temperature interval, the standard evaporating pressure interval is a second pressure interval; in a case where the chilled water inlet temperature is located in a third temperature interval, the standard evaporating pressure interval is a third pressure interval; in a case where the chilled water inlet temperature is located in a fourth temperature interval, the standard evaporating pressure interval is a fourth pressure interval; The arrangement order of the temperature intervals of the freezing inlet water temperature from large to small is: the fourth temperature interval, the third temperature interval, the second temperature interval, and the first temperature interval; the arrangement order of the maximum values of the standard evaporation pressure intervals from large to small is: the maximum value of the fourth pressure interval, the maximum value of the third pressure interval, the maximum value of the second pressure interval, and the maximum value of the first pressure interval; and the arrangement order of the minimum values of the standard evaporation pressure intervals from large to small is: the minimum value of the fourth pressure interval, the minimum value of the third pressure interval, the minimum value of the second pressure interval, and the minimum value of the first pressure interval.

6. The control method of the variable frequency screw rod water chiller unit according to claim 4, characterized in that, The step of controlling the opening degree of the electronic expansion valve according to the comparison result of the actual evaporation pressure and the standard evaporation pressure interval specifically comprises the following steps. If the actual evaporation pressure is not in the standard evaporation pressure interval, the opening degree of the electronic expansion valve is increased or decreased according to the comparison result. Or, if the actual evaporation pressure is in the standard evaporation pressure interval, the suction pressure and the discharge pressure of the compressor are obtained, and the opening degree of the electronic expansion valve is controlled according to the suction pressure and the discharge pressure.

7. The control method of the variable frequency screw rod water chiller unit according to claim 6, characterized in that, The step of increasing or decreasing the opening degree of the electronic expansion valve according to the comparison result specifically comprises the following steps. If the actual evaporation pressure exceeds the standard evaporation pressure interval, the opening degree of the electronic expansion valve is controlled to decrease by a first decreasing opening degree every second interval time length. Or, if the actual evaporation pressure is lower than the standard evaporation pressure interval, the opening degree of the electronic expansion valve is controlled to increase by a second increasing opening degree every second interval time length.

8. The control method of the variable frequency screw rod water chiller unit according to claim 6, characterized in that, The step of controlling the opening degree of the electronic expansion valve according to the suction pressure and the discharge pressure specifically comprises the following steps. If the difference between the discharge pressure and the suction pressure is less than the maximum value of the standard evaporation pressure interval, the opening degree of the electronic expansion valve is controlled to decrease by a second decreasing opening degree every third interval time length. Or, if the difference between the discharge pressure and the suction pressure is greater than or equal to the maximum value of the standard evaporation pressure interval, the opening degree of the electronic expansion valve is kept unchanged.

9. The control method of a variable frequency screw rod water chiller unit according to any one of claims 1 to 8, characterized in that, The step of controlling the electronic expansion valve of the unit to execute the PID adjustment phase specifically comprises the following steps. The compressor current information, the evaporation temperature information, or the suction superheat information of the unit is obtained. The opening degree of the electronic expansion valve is controlled according to the compressor current information, the evaporation temperature information, or the suction superheat information.

10. The control method of the variable frequency screw rod water chiller unit according to claim 9, characterized in that, The step of controlling the opening degree of the electronic expansion valve according to the compressor current information, the evaporation temperature information, or the suction superheat information specifically comprises the following steps. If the compressor current increases by a set current proportion every fourth interval time length, the opening degree of the electronic expansion valve is controlled to increase by a third increasing opening degree.

11. The control method of the variable frequency screw rod water chiller unit according to claim 9, characterized in that, The step of controlling the opening degree of the electronic expansion valve according to the compressor current information, the evaporation temperature information, or the suction superheat information specifically comprises the following steps. In a case where the evaporating temperature is less than or equal to the first evaporating temperature and continuously decreases, the electronic expansion valve is controlled to increase the fourth opening degree every fifth interval time; Or, in a case where the evaporating temperature is greater than the first evaporating temperature and less than or equal to the second evaporating temperature, and the evaporating temperature decreases by a first decreasing temperature every fourth interval time, the electronic expansion valve is controlled to increase the fourth opening degree every fifth interval time and continuously increase a second set number of times; Or, in a case where the evaporating temperature is greater than the second evaporating temperature and less than or equal to a third evaporating temperature, and the evaporating temperature decreases by a second decreasing temperature every fourth interval time, the electronic expansion valve is controlled to increase the fourth opening degree every fifth interval time and continuously increase a third set number of times; Wherein, the first decreasing temperature is less than the second decreasing temperature, and the second set number of times is greater than the third set number of times.

12. The control method of the variable frequency screw rod water chiller unit according to claim 9, characterized in that, The step of controlling the opening degree of the electronic expansion valve according to the compressor current information, the evaporating temperature information or the suction superheat degree information specifically comprises: According to the comparison result of the actual suction superheat degree and the target suction superheat degree, the opening degree of the electronic expansion valve is controlled to increase or decrease; During the increase or decrease of the opening degree of the electronic expansion valve, the cumulative change opening degree of the electronic expansion valve and the superheat degree change trend of the actual suction superheat degree are obtained, and the opening degree of the electronic expansion valve is adjusted in real time according to the cumulative change opening degree and the superheat degree change trend.

13. A control device of a variable frequency screw water chiller, characterized in that, Comprise: The acquisition module is configured to determine that the compressor is started and stably operated, and then acquire an actual starting time length consumed by the compressor in a starting stage; The control module is configured to control the electronic expansion valve of the unit to perform a transition adjustment stage according to the actual starting time length being less than a set starting time length, or control the electronic expansion valve of the unit to perform a PID adjustment stage according to the actual starting time length being greater than or equal to the set starting time length.

14. A variable frequency screw water chiller comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, wherein, The processor executes the program to implement the control method of the variable frequency screw water chiller as claimed in any one of claims 1 to 12.

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