Heat pump unit parallel operation regulation and control method, device and equipment and storage medium

Abstract

The embodiment of the invention discloses a heat pump unit parallel operation regulation and control method, device and equipment and a storage medium. A startup instruction is received, and a startup strategy is executed in response to the startup instruction; after running for a first preset time, periodically detecting the average return water temperature of the parallel unit, and determining a first temperature difference according to a difference value between the average return water temperature and a preset target temperature; determining a temperature difference change rate according to a difference value between the first temperature difference and a second temperature difference, wherein the second temperature difference is the first temperature difference determined in the previous period; according to the first temperature difference, the temperature difference change rate and a preset contrast relationship, determining a startup quantity regulation strategy and a frequency regulation strategy; controlling starting and stopping of compressors of the corresponding heat pump units according to the starting number regulation and control strategy, and performing frequency regulation on the currently started compressors according to the frequency regulation and control strategy; the technical problem that an existing heat pump unit in parallel operation is high in energy consumption can be solved, and the overall energy consumption of the heat pump unit in parallel operation is reduced.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of heat pump control technology, and in particular to a method, device, equipment and storage medium for controlling parallel operation of heat pump units. Background Art

[0002] Heat pump units are widely used in people's work and life due to their high efficiency and environmental protection. As the use of heat pump units becomes more and more extensive, the control requirements for the compressors of heat pump units are also getting higher and higher. Traditional fixed-frequency compressors are difficult to adapt to changing usage requirements due to their fixed operating speed. Therefore, variable frequency technology has begun to be introduced, and the use of variable frequency compressors in heat pump units has become a trend.

[0003] With the widespread use of variable frequency heat pump units in various application scenarios such as refrigeration, hot water, heating and drying, multiple heat pump units are often used in parallel operation in existing application scenarios. The existing control strategy for parallel operation of heat pump units is usually to turn on all heat pump units and uniformly control the operating frequency of the compressors of all heat pump units, that is, all compressors operate based on the same operating frequency. In actual operation, heat pump units operating in parallel may often be in a partial load state. If all compressors operate at the same operating frequency, then at partial load, some compressors may be overloaded or inefficient, while others may be idle or inefficient, which will lead to unnecessary energy waste. Summary of the invention

[0004] The embodiments of the present application provide a method, device, equipment and storage medium for controlling the parallel operation of heat pump units, which can solve the technical problem of high energy consumption of existing heat pump units operating in parallel and reduce the overall energy consumption of heat pump units operating in parallel.

[0005] In a first aspect, an embodiment of the present application provides a heat pump unit parallel operation control method for a parallel unit, wherein the parallel unit is composed of a plurality of heat pump units connected in parallel, and the heat pump unit parallel operation control method comprises:

[0006] receiving a power-on instruction, and executing a power-on strategy in response to the power-on instruction;

[0007] After running for a first preset time, periodically detecting the average return water temperature of the parallel units, and determining a first temperature difference according to the difference between the average return water temperature and a preset target temperature;

[0008] Determine the temperature difference change rate according to the difference between the first temperature difference and the second temperature difference, where the second temperature difference is the first temperature difference determined in the previous cycle;

[0009] According to the first temperature difference and the temperature difference change rate and the preset control relationship, the startup quantity control strategy and the frequency control strategy are determined. The startup quantity control strategy includes the full-start control strategy, the constant temperature startup control strategy, the increase machine control strategy, the reduction machine control strategy and the maintenance strategy. The frequency control strategy includes the full PID frequency regulation strategy, the fixed single PID frequency regulation strategy, the fixed single fixed frequency control strategy, the maintenance frequency strategy and the shutdown strategy;

[0010] The start and stop of the compressor of the corresponding heat pump unit is controlled according to the startup quantity control strategy, and the frequency of the currently turned on compressor is adjusted according to the frequency control strategy.

[0011] In one embodiment, receiving a power-on instruction and executing a power-on strategy in response to the power-on instruction include:

[0012] receiving a startup instruction, responding to the startup instruction, and detecting an average return water temperature of the parallel units;

[0013] Determining a first temperature difference according to a difference between an average return water temperature and a preset target temperature;

[0014] When in cooling mode and the first temperature difference is greater than a first preset threshold value or when in heating mode and the first temperature difference is less than a second preset threshold value, controlling a first number of compressors of heat pump units to start, the first number being the total number of parallel units minus one;

[0015] The frequency of the compressor is controlled according to the preset PID frequency regulation strategy of each heat pump unit currently turned on.

[0016] In one embodiment, according to the first temperature difference, the temperature difference change rate and the preset control relationship, the startup quantity control strategy and the frequency control strategy are determined, including:

[0017] Determining a first dimension parameter according to the first temperature difference and a preset comparison relationship;

[0018] Determine the second dimension parameter according to the temperature difference change rate and the preset comparison relationship;

[0019] According to the intersection of the first dimension parameters and the second dimension parameters, the startup quantity control strategy and the frequency control strategy are determined.

[0020] In one embodiment, determining the first dimension parameter according to the first temperature difference and a preset comparison relationship includes:

[0021] A preset temperature difference interval, wherein a first preset comparison relationship exists between the temperature difference interval and the first dimension parameter;

[0022] Comparing the first temperature difference with the temperature difference interval, and determining a target temperature difference interval corresponding to the first temperature difference;

[0023] Determine a first dimension parameter corresponding to the target temperature difference range according to the first preset comparison relationship;

[0024] According to the temperature difference change rate and the preset control relationship, the second dimension parameters are determined, including:

[0025] A temperature difference change rate interval is preset, and there is a second preset comparison relationship between the temperature difference change rate interval and the second dimension parameter;

[0026] Compare the temperature difference change rate with the temperature difference change rate interval to determine the target temperature difference change rate interval corresponding to the temperature difference change rate;

[0027] The second dimension parameter corresponding to the target temperature difference change rate interval is determined according to the second preset comparison relationship.

[0028] In one embodiment, determining a startup quantity control strategy and a frequency control strategy according to the intersection of the first dimension parameter and the second dimension parameter includes:

[0029] When the first dimension parameter is within the first parameter range, the startup quantity control strategy is determined to be a full-on control strategy, and the frequency control strategy is determined to be a full PID frequency regulation strategy;

[0030] When the first dimension parameter is within the second parameter range, and the second dimension parameter is within the third parameter range, the startup quantity control strategy is determined to be an additional machine control strategy, and the frequency control strategy is determined to be a full PID frequency control strategy;

[0031] When the first dimension parameter is within the fourth parameter range, and the second dimension parameter is within the fifth parameter range, the startup control strategy is determined to be the additional machine control strategy, and the frequency control strategy is determined to be the fixed single PID frequency control strategy;

[0032] When the first dimension parameter is within the sixth parameter range, and the second dimension parameter is within the seventh parameter range, the startup quantity control strategy is determined to be a maintenance strategy, and the frequency control strategy is determined to be a fixed single-unit fixed frequency control strategy;

[0033] When the first dimension parameter is within the eighth parameter range and the second dimension parameter is within the ninth parameter range, the startup quantity control strategy is determined to be a reduction control strategy, and the frequency control strategy is determined to be a full PID frequency control strategy;

[0034] When the first dimension parameter is within the tenth parameter range, the frequency control strategy is determined to be a shutdown strategy, and the shutdown strategy is used to control all compressors to shut down.

[0035] In one embodiment, when the first dimension parameter is within the second parameter range and the second dimension parameter is within the third parameter range, after determining that the startup quantity control strategy is the additional machine control strategy and determining that the frequency control strategy is the full PID frequency control strategy, the method includes:

[0036] Detect the current operating frequency of the compressor of the currently turned-on heat pump unit;

[0037] Control the start and stop of the compressor of the corresponding heat pump unit according to the startup quantity control strategy, including:

[0038] According to the additional machine control strategy, when the current operating frequency meets the preset first condition, a compressor of a heat pump unit is newly turned on. The preset first condition is that the current operating frequency of all the currently turned on heat pump units reaches the preset maximum frequency, limit frequency or limit high frequency, and lasts for the first preset time;

[0039] The newly-activated compressor is controlled to perform frequency regulation according to its own preset PID frequency regulation strategy, and the operating frequency of other currently activated compressors is controlled to reduce the preset fixed frequency.

[0040] In one embodiment, when the first dimension parameter is within the eighth parameter range and the second dimension parameter is within the ninth parameter range, after determining that the startup quantity control strategy is a reduction control strategy and determining that the frequency control strategy is a full PID frequency control strategy, the method includes:

[0041] Detect the current operating frequency of the compressor of the currently turned-on heat pump unit;

[0042] Control the start and stop of the compressor of the corresponding heat pump unit according to the startup quantity control strategy, including:

[0043] According to the machine reduction control strategy, when the current operating frequency meets the preset second condition, the compressor of a heat pump unit is turned off. The preset second condition is that the current operating frequency of all currently turned on heat pump units reaches the preset minimum frequency or is below the limited low frequency.

[0044] In a second aspect, an embodiment of the present application provides a heat pump unit parallel operation control device, which is used for a parallel unit, wherein the parallel unit is composed of a plurality of heat pump units connected in parallel, and the heat pump unit parallel operation control device includes:

[0045] A power-on module, used for receiving a power-on instruction, and executing a power-on strategy in response to the power-on instruction;

[0046] A temperature difference determination module, used for periodically detecting the average return water temperature of the parallel units after running for a preset time, and determining a first temperature difference according to the difference between the average return water temperature and a preset target temperature;

[0047] A change rate determination module, used to determine the temperature difference change rate according to the difference between the first temperature difference and the second temperature difference, where the second temperature difference is the first temperature difference determined in the previous cycle;

[0048] A strategy determination module is used to determine the startup quantity control strategy and the frequency control strategy according to the first temperature difference and the temperature difference change rate and the preset control relationship. The startup quantity control strategy includes the full-start control strategy, the constant temperature startup control strategy, the increase machine control strategy, the reduction machine control strategy and the maintenance strategy. The frequency control strategy includes the full PID frequency regulation strategy, the fixed single PID frequency regulation strategy, the fixed single fixed frequency control strategy, the maintenance frequency strategy and the shutdown strategy;

[0049] The control module is used to control the start and stop of the compressor of the corresponding heat pump unit according to the startup quantity control strategy, and adjust the frequency of the currently turned on compressor according to the frequency control strategy.

[0050] In a third aspect, an embodiment of the present application provides a heat pump unit parallel operation control device, comprising:

[0051] memory and one or more processors;

[0052] A memory for storing one or more programs;

[0053] When one or more programs are executed by one or more processors, the one or more processors implement the heat pump unit parallel operation control method as described in the first aspect.

[0054] In a fourth aspect, an embodiment of the present application provides a storage medium storing computer executable instructions, which, when executed by a computer processor, are used to execute the method for controlling parallel operation of heat pump units as in the first aspect.

[0055] In the embodiment of the present application, when regulating the parallel operation of the heat pump units, after the units are started up for a first preset time, the average return water temperature of the heat pump units is periodically detected, a first temperature difference is determined based on the difference between the average return water temperature and a preset target temperature, a temperature difference change rate is determined based on the difference between the first temperature difference and the second temperature difference, wherein the second temperature difference is the first temperature difference determined in the previous period, a startup quantity control strategy and a frequency control strategy are determined based on the first temperature difference, the temperature difference change rate and a preset comparison relationship, the startup quantity control strategy and the frequency control strategy are controlled according to the startup quantity control strategy, the start and stop of the compressor of the corresponding heat pump unit is controlled according to the startup quantity control strategy, and the frequency of the currently turned on compressor is adjusted according to the frequency control strategy. By adopting the above technical means, the startup quantity control strategy and the frequency control strategy can be jointly determined by the two dimensions of the first temperature difference and the temperature difference change rate. Based on the startup quantity control, the startup quantity of the heat pump unit is adapted to the current load. Compared with the existing parallel operation mode in which all heat pump units are in the on state, this embodiment can shut down some inefficient heat pump units based on the startup quantity control strategy, and increase the heat pump unit when the system is overloaded, so that the startup quantity of the heat pump unit meets the current load demand, thereby reducing the overall energy consumption of the heat pump units running in parallel; in addition, the frequency of the currently turned on compressor is adjusted according to the frequency control strategy. In this embodiment, the first temperature difference and the temperature difference change rate are obtained through periodic detection to control the frequency of the compressor. In the face of the complex environment of actual operation, the frequency control strategy can be determined according to the first temperature difference and the temperature difference change rate corresponding to the actual operation effect, thereby improving the accuracy of the compressor frequency control of the heat pump unit. Based on the improvement of the accuracy of the compressor frequency control, the load adaptability is improved and the frequent start and stop are reduced, and the overall energy consumption of the heat pump units running in parallel is further reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 It is a flow chart of a method for controlling parallel operation of heat pump units provided in an embodiment of the present application;

[0057] Figure 2 It is a structural schematic diagram of a heat pump unit parallel operation control device provided in an embodiment of the present application;

[0058] Figure 3 It is a structural schematic diagram of a heat pump unit parallel operation control device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0059] In order to make the purpose, technical scheme and advantages of the present application clearer, the specific embodiments of the present application are further described in detail below in conjunction with the accompanying drawings. It is understood that the specific embodiments described herein are only used to explain the present application, rather than to limit the present application. It should also be noted that, for the convenience of description, only the part related to the present application but not all the contents are shown in the accompanying drawings. Before discussing the exemplary embodiments in more detail, it should be mentioned that some exemplary embodiments are described as processes or methods depicted as flow charts. Although the flow chart describes each operation (or step) as a sequential process, many of the operations therein can be implemented in parallel, concurrently or simultaneously. In addition, the order of each operation can be rearranged. The process can be terminated when its operation is completed, but it can also have additional steps not included in the accompanying drawings. The process can correspond to a method, a function, a procedure, a subroutine, a subprogram, etc.

[0060] With the widespread use of variable frequency heat pump units in various application scenarios such as refrigeration, hot water, heating and drying, multiple heat pump units are often used in parallel operation in existing application scenarios. The existing control strategy for parallel operation of heat pump units is usually to turn on all heat pump units and uniformly control the operating frequency of the compressors of all heat pump units, that is, all compressors operate based on the same operating frequency. In actual operation, heat pump units operating in parallel may often be in a partial load state. If all compressors operate at the same operating frequency, then at partial load, some compressors may be overloaded or inefficient, while others may be idle or inefficient, which will lead to unnecessary energy waste.

[0061] Based on this, a method, device, equipment and storage medium for controlling the parallel operation of heat pump units in an embodiment of the present application are provided, aiming at, when controlling the parallel operation of the heat pump units, after the first preset time of startup operation, periodically detecting the average return water temperature of the heat pump units, determining a first temperature difference according to the difference between the average return water temperature and a preset target temperature, determining the temperature difference change rate according to the difference between the first temperature difference and the second temperature difference, wherein the second temperature difference is the first temperature difference determined in the previous period, determining a startup quantity control strategy and a frequency control strategy according to the first temperature difference, the temperature difference change rate and a preset control relationship, controlling the start-up quantity control strategy of the corresponding heat pump unit compressor according to the startup quantity control strategy, and adjusting the frequency of the currently turned-on compressor according to the frequency control strategy. By adopting the above technical means, the startup quantity control strategy and the frequency control strategy can be jointly determined by the two dimensions of the first temperature difference and the temperature difference change rate. Based on the startup quantity control, the startup quantity of the heat pump unit is adapted to the current load. Compared with the existing parallel operation mode in which all heat pump units are in the on state, this embodiment can shut down some inefficient heat pump units based on the startup quantity control strategy, and increase the heat pump unit when the system is overloaded, so that the startup quantity of the heat pump unit meets the current load demand, thereby reducing the overall energy consumption of the heat pump units running in parallel; in addition, the frequency of the currently turned on compressor is adjusted according to the frequency control strategy. In this embodiment, the first temperature difference and the temperature difference change rate are obtained through periodic detection to control the frequency of the compressor. In the face of the complex environment of actual operation, the frequency control strategy can be determined according to the first temperature difference and the temperature difference change rate corresponding to the actual operation effect, thereby improving the accuracy of the compressor frequency control of the heat pump unit. Based on the improvement of the accuracy of the compressor frequency control, the load adaptability is improved and the frequent start and stop are reduced, and the overall energy consumption of the heat pump units running in parallel is further reduced.

[0062] Figure 1 A flow chart of a heat pump unit parallel operation control method provided in an embodiment of the present application is given. The heat pump unit parallel operation control method provided in this embodiment can be executed by a heat pump unit parallel operation control device, which can be implemented by software and / or hardware. The heat pump unit parallel operation control device can be composed of two or more physical entities, or can be composed of one physical entity. Generally speaking, the heat pump unit parallel operation control device can be an electronic device corresponding to the heat pump unit, such as air conditioning and floor heating.

[0063] The following description is made by taking the air conditioner as the main body of the heat pump unit parallel operation control method. Figure 1 The heat pump unit parallel operation control method is used for a heat pump unit. The heat pump unit parallel operation control method is used for a parallel unit. The parallel unit is composed of multiple heat pump units connected in parallel. The heat pump unit parallel operation control method specifically includes:

[0064] S101, receiving a power-on instruction, and executing a power-on strategy in response to the power-on instruction.

[0065] After the parallel unit is powered on for the first time, the parallel unit receives the power-on command, responds to the power-on command, and executes the power-on strategy. The power-on strategy includes: obtaining the current operating parameters of the heat pump unit, and determining the current operating mode of the heat pump unit based on the operating parameters. The operating mode includes heating mode or cooling mode. Receive a temperature setting signal, and determine a preset target temperature value based on the temperature setting signal. The temperature setting signal can be input by the user based on a remote control device, or it can be automatically triggered by the controller. For example, if the temperature of the heat pump unit is 26°C before it is shut down, then after the heat pump unit is restarted, the controller automatically triggers the temperature setting signal to determine that the preset target temperature value is 26°C.

[0066] In one embodiment, the preset target temperature value is a heating target temperature value in a heating mode, or the preset target temperature value is a cooling target temperature value in a cooling mode. In the heating mode, a temperature setting signal is received, and the heating target temperature value is determined according to the temperature setting signal. In the cooling mode, a temperature setting signal is received, and the cooling target temperature value is determined according to the temperature setting signal.

[0067] After the heat pump unit is powered on, in order to protect the unit and improve energy efficiency, the compressor will not be turned on until the return water temperature reaches a certain value. Therefore, the startup strategy also includes: detecting the average return water temperature of the parallel unit. The return water temperature of each heat pump unit in the parallel unit can be detected. Based on the fact that the return water temperature of each heat pump unit may be different, the average return water temperature is obtained according to the return water temperature of all heat pump units. It is judged whether the compressor of the heat pump unit needs to be turned on according to the average return water temperature of all heat pump units. The first temperature difference is determined according to the difference between the average return water temperature and the preset target temperature. In the cooling mode and when the first temperature difference is greater than the first preset threshold, or in the heating mode and when the first temperature difference is less than the second preset threshold, the compressors of the first number of heat pump units are controlled to be turned on, and the first number is the total number of parallel units minus one. For example, assuming that there are N heat pump units in the parallel unit, in the cooling mode and when the first temperature difference is greater than the first preset threshold, the compressors of N-1 heat pump units are controlled to be turned on.

[0068] For example, assuming that there are N heat pump units in parallel, in cooling mode, the first preset threshold is the preset cooling start-up differential value. When T01-R01>R03, the compressor of N-1 heat pump units is controlled to start, where T01 is the average return water temperature, R01 is the preset target temperature in cooling mode, that is, the cooling target temperature value, and R03 is the preset cooling start-up differential value.

[0069] For example, assuming that there are N heat pump units in parallel, in heating mode, the second preset threshold is the preset heating start-up differential value. When T01-R02<R05, the compressor of N-1 heat pump units is controlled to be turned on, where T01 is the average return water temperature, R02 is the preset target temperature in heating mode, that is, the heating target temperature value, and R05 is the preset heating start-up differential value.

[0070] It should be noted that in cooling mode, if the first temperature difference is less than or equal to the first preset threshold, the condition for starting the compressor of the heat pump unit is not met, and the compressor is not started and the frequency modulation operation is not performed temporarily. In heating mode, if the first temperature difference is greater than or equal to the second preset threshold, the condition for starting the compressor of the heat pump unit is not met, and the compressor is not started and the frequency modulation operation is not performed temporarily.

[0071] When the first temperature difference is greater than the first preset threshold value in the cooling mode, or when the first temperature difference is less than the second preset threshold value in the heating mode, after the compressors of the first number of heat pump units are controlled to be turned on, the corresponding compressors are controlled to first run for a preset time at a preset platform frequency. After starting the compressors, by controlling the compressors to run for a period of time at the platform frequency, it is helpful to reduce temperature fluctuations in the startup phase, thereby improving user comfort, and helping to improve the stability of the internal pressure of the heat pump unit, thereby improving the overall reliability of the operation of the heat pump unit.

[0072] After the compressor runs for a preset time at the preset platform frequency, the frequency of the compressor is regulated according to the preset PID frequency regulation strategy of each currently turned on heat pump unit. Each heat pump unit has its own corresponding PID regulation strategy preset. Therefore, during the execution of the startup strategy, if the compressor of the heat pump unit is turned on, the frequency of the compressor can be regulated according to its own preset PID regulation strategy.

[0073] As described above, by controlling the compressors of the heat pump units whose total number of parallel units is reduced by one to turn on when the first temperature difference is greater than the first preset threshold in the cooling mode, or when the first temperature difference is less than the second preset threshold in the heating mode, and reserving one heat pump unit in the off state, it is possible to avoid frequent starts and stops of the units due to full load operation right after startup, thereby improving the reliability and stability of the startup operation of the parallel units.

[0074] S102: After running for a first preset time, periodically detect the average return water temperature of the parallel units, and determine a first temperature difference according to the difference between the average return water temperature and a preset target temperature.

[0075] The compressor is frequency-controlled according to the preset PID frequency modulation strategy of each currently turned on heat pump unit. After the compressor runs for the first preset time, the average return water temperature of the heat pump unit is periodically detected, and the first temperature difference is determined according to the difference between the average return water temperature and the preset target temperature. For example, assuming that the cycle is 10 minutes and the preset target temperature is 26°C, the average return water temperature is detected every 10 minutes. Assuming that the average return water temperature detected this time is 30°C, the first temperature difference of this cycle is determined to be 4°C according to the difference between the average return water temperature of 30°C and the preset target temperature of 26°C.

[0076] Exemplarily, the first preset time may be set to be the same as the cycle time. For example, if the cycle time is 10 minutes, the first preset time may be set to 10 minutes.

[0077] As described above, by periodically detecting the average return water temperature and obtaining the first temperature difference of the current cycle based on the difference between the average return water temperature and the preset target temperature, it is possible to subsequently determine whether to increase or decrease the number of machines or make no adjustment based on changes in the first temperature differences corresponding to multiple cycles, or determine the frequency control strategy of the compressor of each turned-on heat pump unit. Compared with the existing method in which all compressors of parallel units operate at the same frequency, this embodiment adjusts the startup quantity control strategy and the frequency control strategy based on the first temperature difference corresponding to the actual operating result, which can improve the adaptability of the parallel units to the load required by the actual environment, thereby reducing the overall energy consumption of the parallel units.

[0078] S103, determining a temperature difference change rate according to a difference between a first temperature difference and a second temperature difference, where the second temperature difference is the first temperature difference determined in a previous cycle.

[0079] The average return water temperature of the parallel unit is detected periodically, and the first temperature difference of this cycle is determined according to the difference between the average return water temperature and the preset target temperature, and the first temperature difference determined in the previous cycle is recorded as the second temperature difference. The temperature difference change rate can be determined according to the difference between the first temperature difference and the second temperature difference. Exemplarily, the temperature difference change rate is obtained according to the ratio of the difference between the first temperature difference and the second temperature difference to the cycle (duration). For example, the first temperature difference (i.e., the second temperature difference) determined in the previous cycle is 8°C, and the first temperature difference determined in this cycle is 4°C. The difference between the two is 4°C, and the cycle (duration) is 20 minutes, then the temperature difference change rate is 0.2°C / min.

[0080] As mentioned above, by periodically detecting the average return water temperature, the first temperature difference of the corresponding period and the temperature difference change rate of two adjacent periods are obtained. Subsequently, the startup quantity control strategy and the frequency control strategy can be determined based on the two dimensions of the first temperature difference and the temperature difference change rate, thereby realizing multi-dimensional considerations, thereby improving the accuracy of temperature control and the adaptability of the parallel startup quantity to actual needs, thereby reducing the overall energy consumption of the parallel unit operation.

[0081] S104. Determine the startup quantity control strategy and the frequency control strategy according to the first temperature difference, the temperature difference change rate and the preset control relationship. The startup quantity control strategy includes the full-start control strategy, the constant temperature startup control strategy, the increase machine control strategy, the reduction machine control strategy and the maintenance strategy. The frequency control strategy includes the full PID frequency regulation strategy, the fixed single PID frequency regulation strategy, the fixed single fixed frequency control strategy, the maintenance frequency strategy and the shutdown strategy.

[0082] The startup quantity control strategy and frequency control strategy are preset. Among them, the startup quantity control strategy includes the full-on control strategy, the constant temperature startup control strategy, the additional machine control strategy, the reduced machine control strategy and the maintenance strategy. The full-on control strategy is to turn on the compressors of all heat pump units. For example, if there are 10 heat pump units in parallel, when the full-on control strategy is executed, the compressors of 10 heat pump units are turned on. The constant temperature startup control strategy includes: turning on the number of operations before the constant temperature shutdown minus one. For example, if 5 heat pump units are running before the constant temperature shutdown, when the constant temperature startup control strategy is executed, the compressors of 4 heat pump units are turned on. The additional machine control strategy includes: directly turning on one additional unit (i.e., adding one unit); or, when the current operating frequency meets the preset first condition, turning on the compressor of one heat pump unit. Among them, the preset first condition is that the current operating frequency of all currently turned on heat pump units reaches the preset maximum frequency (K01), limit frequency (K02) or limit high frequency frequency (K03), and lasts for the first preset time. Exemplarily, the first preset condition is that the current operating frequency of all heat pump units currently turned on reaches the preset maximum frequency (K01); or, the first preset condition is that the current operating frequency of all heat pump units currently turned on reaches the preset limit frequency (K02); or, the first preset condition is that the current operating frequency of all heat pump units currently turned on reaches the preset limit high-frequency frequency (K03); or the first preset condition is that the current operating frequency of some heat pump units currently turned on reaches the preset maximum frequency (K01), the current operating frequency of some heat pump units reaches the preset limit frequency (K02), and the current operating frequency of some heat pump units reaches the preset limit high-frequency frequency (K03). It should be noted that when a new compressor of a heat pump unit is turned on, priority is given to turning on heat pump units with short running time and no faults. It should be noted that after the number of units turned on changes, the corresponding frequency is calculated according to the new cycle according to the preset first condition. It should be noted that when a new compressor of a heat pump unit is turned on, the frequency of the compressors of all the heat pump units that have been turned on will be reduced by a preset frequency (for example, the preset KO1 frequency); if the frequency of the compressors of all the heat pump units that have been turned on is the minimum frequency, the current frequency will be maintained. The reduction control strategy includes: directly shutting down the compressor of a heat pump unit (i.e. reducing one unit); or, when the current operating frequency meets the preset second condition, shutting down the compressor of a heat pump unit. Among them, the preset second condition is that the current operating frequency of all the heat pump units that are currently turned on reaches the preset minimum frequency or is below the limited low frequency. It should be noted that when shutting down the compressor of a heat pump unit, the heat pump unit with the longest running time will be shut down first. It should be noted that in the case of non-emergency stop, when there is only one heat pump unit with the compressor turned on, the reduction control strategy will not be executed. The maintenance strategy is to maintain the number of heat pump units currently in operation, that is, no increase or decrease.It should be noted that when executing the maintenance strategy, if the currently running heat pump unit fails and stops, it is necessary to open the compressors of the corresponding number of heat pump units to maintain the current number of units in operation unchanged.

[0083] The frequency control strategies include full PID frequency regulation strategy, fixed single PID frequency regulation strategy, fixed single fixed frequency control strategy, frequency maintenance strategy and shutdown strategy. Among them, the full PID control strategy is to control the frequency of the compressor according to the preset PID frequency regulation strategy of each currently turned on heat pump unit. The fixed single PID control strategy is to select one of the heat pump units to adjust the frequency of the compressor according to its own preset PID control strategy, while the compressor frequency of other currently running heat pump units remains unchanged. Among them, when selecting a fixed single heat pump unit according to its own preset PID control strategy, when increasing the frequency, the heat pump unit with the smallest frequency increase among the currently running heat pump units is given priority; when reducing the frequency, the heat pump unit with the highest frequency reduction among the currently running heat pump units is given priority. The fixed single fixed frequency control strategy is to select one of the heat pump units to adjust the frequency of the compressor according to the preset fixed frequency, while the compressor frequency of other currently running heat pump units remains unchanged. The preset fixed frequencies include fixed frequency modulation 1 (K06), fixed frequency modulation 2 (K07), fixed frequency modulation 3 (K08), fixed frequency modulation 4 (K09) and fixed frequency modulation 5 (K10). The frequency maintenance strategy is to maintain the current frequency without frequency modulation. The shutdown strategy is to shut down the compressors of all heat pump units.

[0084] It should be noted that when the preset conditions are met and the full-open control strategy, constant temperature start-up control strategy or emergency stop is triggered, it will be executed immediately without waiting for the frequency modulation cycle.

[0085] In one embodiment, a temperature difference interval is preset, and a first preset comparison relationship exists between the temperature difference interval and the first dimension parameter (i.e., the parameters of the startup quantity control strategy and the frequency control strategy). For example, the greater the temperature difference, the greater the corresponding startup quantity. The greater the temperature difference, the higher the required capacity demand, and the more heat pump units need to be turned on. Exemplarily, in the cooling mode, under the same temperature difference change rate, the temperature difference interval [R03, R03+4) (unit is ℃) corresponds to the startup quantity control strategy is a constant temperature startup control strategy, and the corresponding frequency control strategy is a full PID control strategy. The temperature difference interval [R03+4, +∞) (unit is ℃) corresponds to the startup quantity control strategy is a full-on control strategy, and the corresponding frequency control strategy is a full PID control strategy. A temperature difference change rate interval is preset, and a second preset comparison relationship exists between the temperature difference change rate interval and the second dimension parameter (i.e., the parameters of the startup quantity control strategy and the frequency control strategy). Exemplarily, under the same temperature difference value, the temperature difference change rate interval [-0.25, 0) (unit is ℃ / min) the startup quantity control strategy is the adding machine control strategy, and the corresponding frequency control strategy is the full PID control strategy. The temperature difference change rate interval [-0.5, -0.25) (unit is ℃ / min) the startup quantity control strategy is the maintenance strategy, and the corresponding frequency control strategy is the fixed single PID control strategy. By integrating the first preset control relationship and the second preset control relationship, a complete preset control relationship in two dimensions can be obtained. As described above, through the first preset control relationship, when the temperature difference is large, the startup quantity is increased or the frequency is adjusted based on the PID control strategy, so that more compressors are involved in the work, so as to reduce the temperature difference as soon as possible, thereby shortening the time to reach the preset target temperature, thereby improving the user experience. Through the second preset control relationship, when the temperature difference change rate drops rapidly, the number of startups is increased or the frequency is adjusted based on the full PID control strategy to increase the temperature difference change speed and speed up the speed of reducing the temperature difference. When the temperature difference change rate rises rapidly, the number of startups is maintained or reduced or the fixed frequency is reduced. This means that the temperature difference change rate at this time meets the requirement of reaching the preset target temperature within the preset target temperature reaching time. The number of startups or the frequency can be appropriately reduced to achieve energy saving without affecting the preset target temperature reaching time, thereby further improving the user experience.

[0086] In one embodiment, a comparison table of preset comparison relationships is provided for cooling mode, as shown in Tables 1 and 2 below. Among them, the full-open control strategy is represented by 11; the constant temperature start-up control strategy is represented by 12; the control strategy of adding a new machine to start is represented by 131; the control strategy of adding a compressor of a heat pump unit is represented by 132 to meet the current operating frequency of all currently turned on heat pump units reaching the preset maximum frequency (K01) or the limit frequency (K02); the control strategy of adding a compressor of a heat pump unit is represented by 133 to meet the current operating frequency of all currently turned on heat pump units reaching the preset maximum frequency (K01) or the limit high frequency frequency (K03); the control strategy of reducing the compressor of a heat pump unit is represented by 141 to close the compressor of a heat pump unit; the control strategy of reducing the compressor of a heat pump unit is represented by 142 to close the compressor of a heat pump unit when the current operating frequency meets the preset second condition; the maintenance strategy is represented by 15. The full PID frequency regulation strategy is represented by 21, and the fixed single-unit PID frequency regulation strategy is represented by 22; the fixed single-unit fixed frequency control strategy that executes fixed frequency 1 is represented by 231, the fixed single-unit fixed frequency control strategy that executes fixed frequency 2 is represented by 232, the fixed single-unit fixed frequency control strategy that executes fixed frequency 3 is represented by 233, the fixed single-unit fixed frequency control strategy that executes fixed frequency 4 is represented by 234, and the fixed single-unit fixed frequency control strategy that executes fixed frequency 5 is represented by 235; the frequency maintenance strategy is represented by 24; and the shutdown strategy is represented by 25.

[0087] Table 1:

[0088]

[0089]

[0090] Table 2:

[0091]

[0092] In Table 1 and Table 2, △T (℃) represents the temperature difference range, and Φ (℃ / min) represents the temperature difference change rate range. R03 represents the refrigeration startup hysteresis value, and R04 represents the refrigeration shutdown hysteresis value. Through the preset correspondence relationship in Table 1 and Table 2, when the corresponding first temperature difference is obtained in the periodic detection, the first temperature difference can be compared with the temperature difference range to determine the target temperature difference range corresponding to the first temperature difference. For example, when the first temperature difference is 4℃, when R03=3, the corresponding target temperature difference range is [R03, R03+4)(unit is ℃), that is, [3,7)(unit is ℃), that is, zone B. Determine the first dimensional parameter corresponding to the target temperature difference range according to the first preset comparison relationship. The first dimension parameter corresponding to the target temperature difference interval is a plurality of parameters. For example, the control strategies (i.e., the startup quantity control strategy and the frequency control strategy) of a whole column (i.e., the column corresponding to zone B) corresponding to the temperature difference interval [R03, R03+4) (unit: °C) in Table 1 are all first dimension parameters, i.e., 12 or 131 (21) and 12 (21). The temperature difference change rate is compared with the temperature difference change rate interval to determine the target temperature difference change rate interval corresponding to the temperature difference change rate. For example, the temperature difference change rate is 0.2 °C / min, and its corresponding target temperature difference change rate interval is [0, 0.5) (unit: °C / min), i.e., zone d. The second dimension parameter corresponding to the target temperature difference change interval is determined according to the second preset comparison relationship. The second dimension parameter corresponding to the target temperature difference change rate interval is a plurality of parameters. For example, the target control strategies (i.e., the startup quantity control strategy and the frequency control strategy) of a whole row (i.e., the row corresponding to the temperature difference change rate interval [0, 0.5) (unit: °C / min) in Table 1 are all second dimension parameters, i.e., 11 (21), 12 or 131 (21), 132 (21) and 133 (22). According to the intersection of the first dimension parameter and the second dimension parameter, it is determined to be the corresponding target control strategy, i.e., the corresponding startup quantity control strategy and frequency control strategy. For example, the intersection of the first dimension parameter and the second dimension parameter is 12 or 131 (21) (i.e., the intersection of the B zone and the d zone in Table 1), which determines that the startup quantity control strategy is a constant temperature startup control strategy or a newly added compressor control strategy for starting a heat pump unit, and the frequency control strategy is a full PID frequency regulation strategy.

[0093] As mentioned above, by periodically detecting the average return water temperature, the first temperature difference of the corresponding period and the temperature difference change rate of two adjacent periods are obtained, and the startup quantity control strategy and the frequency control strategy are determined based on the two dimensions of the first temperature difference and the temperature difference change rate, so as to realize multi-dimensional consideration, thereby improving the accuracy of temperature control, and improving the adaptability of the startup quantity of parallel units to the actual energy demand, thereby reducing the overall energy consumption of the parallel units.

[0094] In one embodiment, a comparison table of preset comparison relationships is provided for heating mode, as shown in Tables 3 and 4 below. Among them, the full-open control strategy is represented by 11; the constant temperature start-up control strategy is represented by 12; the control strategy of adding a new machine to start is represented by 131; the control strategy of adding a compressor of a heat pump unit is represented by 132 to meet the current operating frequency of all currently turned on heat pump units reaching the preset maximum frequency (K01) or the limit frequency (K02); the control strategy of adding a compressor of a heat pump unit is represented by 133 to meet the current operating frequency of all currently turned on heat pump units reaching the preset maximum frequency (K01) or the limit high frequency frequency (K03); the control strategy of reducing the compressor of a heat pump unit is represented by 141 to close the compressor of a heat pump unit; the control strategy of reducing the compressor of a heat pump unit is represented by 142 to close the compressor of a heat pump unit when the current operating frequency meets the preset second condition; and the maintenance strategy is represented by 15. The full PID frequency regulation strategy is represented by 21, and the fixed single-unit PID frequency regulation strategy is represented by 22; the fixed single-unit fixed frequency control strategy that executes fixed frequency 1 is represented by 231, the fixed single-unit fixed frequency control strategy that executes fixed frequency 2 is represented by 232, the fixed single-unit fixed frequency control strategy that executes fixed frequency 3 is represented by 233, the fixed single-unit fixed frequency control strategy that executes fixed frequency 4 is represented by 234, and the fixed single-unit fixed frequency control strategy that executes fixed frequency 5 is represented by 235; the frequency maintenance strategy is represented by 24; and the shutdown strategy is represented by 25.

[0095] Table 3:

[0096]

[0097] Table 4:

[0098]

[0099] In Table 3 and Table 4, △T (℃) represents the temperature difference range, and Φ (℃ / min) represents the temperature difference change rate range. R05 represents the heating start-up hysteresis value, and R06 represents the heating stop hysteresis value. According to the preset correspondence in Table 3 and Table 4, when the corresponding first temperature difference is obtained by periodic detection, the first temperature difference can be compared with the temperature difference range to determine the target temperature difference range corresponding to the first temperature difference. For example, when the first temperature difference is 4℃, when R05=3, the corresponding target temperature difference range is [R05, R05+2)(unit is ℃), that is, [3, 5)(unit is ℃), that is, zone B. Determine the first dimensional parameter corresponding to the target temperature difference range according to the first preset comparison relationship. The first dimension parameter corresponding to the target temperature difference interval is a plurality of parameters. For example, the control strategies (i.e., the startup quantity control strategy and the frequency control strategy) of a whole column (i.e., the column corresponding to zone B) corresponding to the temperature difference interval [R05, R05+2) (unit is ℃) in Table 3 are all first dimension parameters, i.e., 12 or 131 (21) and 12 (21). The temperature difference change rate is compared with the temperature difference change rate interval to determine the target temperature difference change rate interval corresponding to the temperature difference change rate. For example, the temperature difference change rate is -0.2℃ / min, and its corresponding target temperature difference change rate interval is (-0.5, 0] (unit is ℃ / min), i.e., zone d. The second dimension parameter corresponding to the target temperature difference change rate interval is determined according to the second preset comparison relationship. The second dimension parameter corresponding to the target temperature difference change rate interval is a plurality of parameters. For example, the target control strategies (i.e., the startup quantity control strategy and the frequency control strategy) of a whole row (i.e., the row corresponding to zone d) corresponding to the temperature difference change rate interval (-0.5, 0] (unit is ℃ / min) in Table 3 are all second dimension parameters, i.e., 11(21), 12 or 131(21), 132(21) and 133(22). According to the intersection of the first dimension parameter and the second dimension parameter, it is determined to be the corresponding target control strategy, that is, the corresponding startup quantity control strategy and frequency control strategy. For example, the intersection of the first dimension parameter and the second dimension parameter is 12 or 131(21) (that is, the intersection of area B and area D in Table 1), that is, the startup quantity control strategy is determined to be a constant temperature startup control strategy or a new compressor control strategy for starting a heat pump unit, and the frequency control strategy is a full PID frequency regulation strategy.

[0100] As mentioned above, by periodically detecting the average return water temperature, the first temperature difference of the corresponding period and the temperature difference change rate of two adjacent periods are obtained, and the startup quantity control strategy and the frequency control strategy are determined based on the two dimensions of the first temperature difference and the temperature difference change rate, so as to realize multi-dimensional consideration, thereby improving the accuracy of temperature control, and improving the adaptability of the startup quantity of parallel units to the actual energy demand, thereby reducing the overall energy consumption of the parallel units.

[0101] In one embodiment, when the first dimension parameter is in the first parameter range, the startup quantity control strategy is determined to be a full-on control strategy, and the frequency control strategy is determined to be a full PID frequency modulation strategy; for example, the A zone in Table 1 and Table 3. When the first dimension parameter is in the second parameter range, and the second dimension parameter is in the third parameter range, the startup quantity control strategy is determined to be an additional machine control strategy, and the frequency control strategy is determined to be a full PID frequency modulation strategy; for example, the intersection of the CD zone and the ad zone in Table 1 and Table 3. When the first dimension parameter is in the fourth parameter range, and the second dimension parameter is in the fifth parameter range, the startup control strategy is determined to be an additional machine control strategy, and the frequency control strategy is determined to be a fixed single PID frequency modulation strategy; for example, the intersection of the E zone and the ad zone in Table 1 and Table 3. When the first dimension parameter is in the sixth parameter range, and the second dimension parameter is in the seventh parameter range, the startup quantity control strategy is determined to be a maintenance strategy, and the frequency control strategy is determined to be a fixed single fixed frequency control strategy; for example, the intersection of the DE zone and the gh zone in Table 1 and Table 3. When the first dimension parameter is in the eighth parameter range, and the second dimension parameter is in the ninth parameter range, the startup quantity control strategy is determined to be a reduction control strategy, and the frequency control strategy is determined to be a full PID frequency regulation strategy; for example, the intersection of the G zone and the fg zone, and the intersection of the H zone and the ef zone in Table 2 and Table 4. When the first dimension parameter is in the tenth parameter range, the frequency control strategy is determined to be a shutdown strategy, and the shutdown strategy is used to control all compressors to shut down; for example, the constant shutdown zone in Table 2 and Table 4.

[0102] S105, controlling the start and stop of the compressor of the corresponding heat pump unit according to the startup quantity control strategy, and adjusting the frequency of the currently started compressor according to the frequency control strategy.

[0103] After determining the target control strategy corresponding to this cycle, that is, after determining the corresponding startup quantity control strategy and frequency control strategy, the start and stop of the compressor of the corresponding heat pump unit is controlled according to the startup quantity control strategy to control the compressors of the corresponding number of heat pump units to be in operation; and the frequency of the currently turned on compressor is adjusted according to the frequency control strategy. Exemplarily, according to the aforementioned embodiment, it is assumed that the target control strategy corresponding to this cycle is 12 or 131 (21), that is, the startup quantity control strategy is a constant temperature startup control strategy or a newly started compressor control strategy for a heat pump unit, and the frequency control strategy is a full PID frequency modulation strategy. Exemplarily, according to the constant temperature startup control strategy, the number of operations before the constant temperature shutdown is determined, and the compressors of the heat pump unit whose number of operations before the constant temperature shutdown is reduced by one are turned on; according to the full PID frequency modulation strategy, the frequency of the compressor is controlled according to the preset PID frequency modulation strategy of each of the currently turned on heat pump units.

[0104] In one embodiment, when the first dimension parameter is within the second parameter range, and the second dimension parameter is within the third parameter range, after determining that the startup quantity control strategy is the additional machine control strategy, and determining that the frequency control strategy is the full PID frequency modulation strategy, the current operating frequency of the compressor of the currently turned on heat pump unit is detected. According to the additional machine control strategy, when the current operating frequency meets the preset first condition, a new compressor of a heat pump unit is turned on, and the preset first condition is that the current operating frequency of all currently turned on heat pump units reaches the preset maximum frequency, limit frequency or limit high frequency, and lasts for the first preset time. The newly turned on compressor is controlled to perform frequency control according to its own preset PID frequency modulation strategy, and the operating frequency of other currently turned on compressors is controlled to reduce the preset fixed frequency. It should be noted that if the operating frequency of other currently turned on compressors is the lowest operating frequency, it is not necessary to reduce the preset fixed frequency, and the current lowest operating frequency can be maintained.

[0105] In one embodiment, when the first dimension parameter is in the eighth parameter range and the second dimension parameter is in the ninth parameter range, after determining that the startup quantity control strategy is the reduction control strategy and the frequency control strategy is the full PID frequency regulation strategy, the current operating frequency of the compressor of the currently turned on heat pump unit is detected. According to the reduction control strategy, when the current operating frequency meets the preset second condition, the compressor of a heat pump unit is turned off, and the preset second condition is that the current operating frequency of all the currently turned on heat pump units reaches the preset minimum frequency or is below the limited low frequency.

[0106] It should be noted that when executing the corresponding startup quantity control strategy, when the heat pump unit that needs to be operated fails and stops, the unstarted heat pump unit is turned on instead and operates according to the corresponding frequency control strategy.

[0107] In the above, after the first preset time of startup operation, the average return water temperature of the heat pump unit is periodically detected, the first temperature difference is determined according to the difference between the average return water temperature and the preset target temperature, the temperature difference change rate is determined according to the difference between the first temperature difference and the second temperature difference, wherein the second temperature difference is the first temperature difference determined in the previous period, the startup quantity control strategy and the frequency control strategy are determined according to the first temperature difference, the temperature difference change rate and the preset comparison relationship, the startup quantity control strategy is controlled according to the startup quantity control strategy, and the frequency of the currently turned on compressor is adjusted according to the frequency control strategy. By adopting the above technical means, the startup quantity control strategy and the frequency control strategy can be jointly determined by the two dimensions of the first temperature difference and the temperature difference change rate. Based on the startup quantity control, the startup quantity of the heat pump unit is adapted to the current load. Compared with the existing parallel operation mode in which all heat pump units are in the on state, this embodiment can shut down some inefficient heat pump units based on the startup quantity control strategy, and increase the heat pump unit when the system is overloaded, so that the startup quantity of the heat pump unit meets the current load demand, thereby reducing the overall energy consumption of the heat pump units running in parallel; in addition, the frequency of the currently turned on compressor is adjusted according to the frequency control strategy. In this embodiment, the first temperature difference and the temperature difference change rate are obtained through periodic detection to control the frequency of the compressor. In the face of the complex environment of actual operation, the frequency control strategy can be determined according to the first temperature difference and the temperature difference change rate corresponding to the actual operation effect, thereby improving the accuracy of the compressor frequency control of the heat pump unit. Based on the improvement of the accuracy of the compressor frequency control, the load adaptability is improved and the frequent start and stop are reduced, and the overall energy consumption of the heat pump units running in parallel is further reduced.

[0108] In one embodiment, a comparison between a parameter code and specific content is provided, as shown in Table 5:

[0109] Table 5:

[0110]

[0111]

[0112] In one embodiment, the preset temperature target is the heating target temperature in the heating mode. Exemplarily, when the current operating mode of the heat pump unit is the heating mode, a temperature setting signal is received, and the heating target temperature is determined according to the temperature setting signal. In the heating mode, the average return water temperature of the parallel unit is periodically detected, and the first temperature difference is determined according to the difference between the average return water temperature and the first target temperature. Exemplarily, the first temperature difference ΔT=R01-T01, where R01 is the heating target temperature and T01 is the average return water temperature; the temperature difference change rate Φ=(ΔT(n-1)-ΔT) / M01; where M01 is the frequency modulation period, which can be understood as the duration of the period detection, and ΔT(n-1) is the first temperature difference determined in the previous period.

[0113] In one embodiment, the preset temperature target is the cooling target temperature in the cooling mode. Exemplarily, when the current operating mode of the heat pump unit is the cooling mode, a temperature setting signal is received, and the cooling target temperature is determined according to the temperature setting signal. In the cooling mode, the average return water temperature of the parallel unit is periodically detected, and the first temperature difference is determined according to the difference between the average return water temperature and the first target temperature. Exemplarily, the first temperature difference ΔT=T01-R02, where R02 is the cooling target temperature and T01 is the average return water temperature; the temperature difference change rate Φ=(ΔT-ΔT(n-1)) / M01; where M01 is the frequency modulation period, which can be understood as the duration of the periodic detection, and ΔT(n-1) is the first temperature difference determined in the previous period.

[0114] In heating mode or cooling mode, the average return water temperature can be periodically detected to obtain the first temperature difference and the temperature difference change rate in the corresponding period. Based on the preset comparison relationship (i.e., Table 1-4 above), the first temperature difference can be compared with the temperature difference interval △T to determine the target temperature difference interval corresponding to the first temperature difference. The temperature difference change rate corresponding to this cycle is compared with the temperature difference change rate interval to determine the target temperature difference change rate interval corresponding to the temperature difference change rate. According to the columns corresponding to the target temperature difference interval and the rows corresponding to the target temperature difference change rate interval, the intersecting target control strategy (for example, 12 or 131 (21)) is determined, and the corresponding compressor is controlled to start and stop according to the target control strategy, and the corresponding compressor is controlled to perform the corresponding frequency adjustment processing.

[0115] For example, in the cooling mode, referring to Table 1 and Table 2 above, assuming that the first temperature difference (i.e., the second temperature difference) determined in the previous cycle is 8°C, the first temperature difference determined in this cycle is 4°C, the difference between the two is 4°C, and the cycle time is 20 minutes, then the temperature difference change rate is 0.2°C / min. Assuming R03=3, the corresponding target temperature difference interval is [R03, R03+4) (unit is °C), that is, [3, 7) (unit is °C), which corresponds to area B in Table 1; the temperature difference change rate is 0.2°C / min corresponding to area d in Table 1. At this time, all the heat pump units in operation are already running at high frequency, but the average return water temperature detected is still rising, which indicates that the capacity of the existing heat pump units that have been turned on is insufficient to meet the current demand. In order to ensure the overall stable operation of the parallel unit and prevent damage to the unit or performance degradation due to overheating, it is necessary to immediately start the compressor of an additional heat pump unit to increase the cooling capacity. Therefore, the corresponding startup quantity control strategy is determined to be a constant temperature startup control strategy or a compressor addition control strategy for a new heat pump unit, and the frequency control strategy is a full PID frequency modulation strategy.

[0116] Exemplarily, in the cooling mode, referring to Table 1 and Table 2 above, if the first temperature difference is in the A range, it means that the required capacity is higher, and all heat pump units need to be turned on. Therefore, the corresponding startup quantity control strategy is determined to be a full-on control strategy, and the frequency control strategy is a full PID frequency modulation strategy to provide the maximum cooling capacity supply.

[0117] Exemplarily, in the cooling mode, referring to Table 1 and Table 2 above, when the average return water temperature has dropped to the range of the preset target temperature (i.e., the target cooling temperature), that is, the first temperature difference value is in the F interval. Then, it is detected that the temperature difference change rate fluctuates in the ae interval, and the average return water temperature has an upward trend, the number of currently running heat pump units and the operating frequency of each compressor can be kept unchanged to ensure stable operation of the system, that is, the startup quantity control strategy is determined to be the maintenance strategy, and the frequency control strategy is the maintenance frequency strategy.

[0118] For example, in cooling mode, referring to Tables 1 and 2 above, when the average return water temperature drops to the FH range and the temperature difference change rate is in the fh range with a faster cooling rate, it means that the current average return water temperature is close to the demand, so the frequency can be quickly reduced and the heat pump units can be reduced according to the conditions.

[0119] Exemplarily, in the cooling mode, referring to Tables 1 and 2 above, when the first temperature difference is in the G interval and the cooling speed is relatively fast, that is, the temperature difference change rate is in the g interval, it means that the current capacity demand is not high, and the number of running heat pump units can be reduced, that is, the startup quantity control strategy is determined as: when the current operating frequency meets the preset second condition, a heat pump unit compressor is turned off to reduce the machine control strategy; and the frequency control strategy is determined to be a full PID control strategy.

[0120] Exemplarily, in the cooling mode, referring to Table 1 and Table 2 above, when the first temperature difference decreases to the constant stop interval, all heat pump units are controlled to shut down, that is, the compressors of all heat pump units are turned off.

[0121] As described above, by dynamically adjusting the number of units and compressor frequency of the parallel units to be increased or decreased according to the temperature difference change rate of the average return water temperature, the number of heat pump units that are turned on can be quickly locked, thereby improving the adaptability of the parallel units to changes in the external environment, making energy consumption more reasonable, and thus enhancing the user experience; secondly, through the parallel operation control method of the heat pump units provided in this embodiment, the temperature fluctuation is smaller, and the indoor and outdoor temperature difference is more stable, thereby reducing the number of unnecessary switching operations, and thus extending the service life of the equipment.

[0122] As mentioned above, during the parallel operation control of the heat pump units, after the first preset time of startup operation, the average return water temperature of the heat pump units is periodically detected, and the first temperature difference is determined according to the difference between the average return water temperature and the preset target temperature, and the temperature difference change rate is determined according to the difference between the first temperature difference and the second temperature difference, wherein the second temperature difference is the first temperature difference determined in the previous cycle, and the startup quantity control strategy and the frequency control strategy are determined according to the first temperature difference, the temperature difference change rate and the preset comparison relationship, and the startup quantity control strategy and the frequency control strategy are controlled according to the startup quantity control strategy. The start and stop of the compressor of the corresponding heat pump unit are controlled according to the startup quantity control strategy, and the frequency of the currently turned on compressor is adjusted according to the frequency control strategy. By adopting the above technical means, the startup quantity control strategy and the frequency control strategy can be jointly determined by the two dimensions of the first temperature difference and the temperature difference change rate. Based on the startup quantity control, the startup quantity of the heat pump unit is adapted to the current load. Compared with the existing parallel operation mode in which all heat pump units are in the on state, this embodiment can shut down some inefficient heat pump units based on the startup quantity control strategy, and increase the heat pump unit when the system is overloaded, so that the startup quantity of the heat pump unit meets the current load demand, thereby reducing the overall energy consumption of the heat pump units running in parallel; in addition, the frequency of the currently turned on compressor is adjusted according to the frequency control strategy. In this embodiment, the first temperature difference and the temperature difference change rate are obtained through periodic detection to control the frequency of the compressor. In the face of the complex environment of actual operation, the frequency control strategy can be determined according to the first temperature difference and the temperature difference change rate corresponding to the actual operation effect, thereby improving the accuracy of the compressor frequency control of the heat pump unit. Based on the improvement of the accuracy of the compressor frequency control, the load adaptability is improved and the frequent start and stop are reduced, and the overall energy consumption of the heat pump units running in parallel is further reduced.

[0123] Based on the above embodiments, Figure 2 This is a schematic diagram of the structure of a heat pump unit parallel operation control device provided in an embodiment of the present application. Figure 2 The heat pump unit parallel operation control device provided in this embodiment is used for a heat pump unit. The heat pump unit parallel operation control device is used for a parallel unit. The parallel unit is composed of multiple heat pump units connected in parallel. The heat pump unit parallel operation control device specifically includes: a startup module 21, a temperature difference determination module 22, a change rate determination module 23, a strategy determination module 24 and a control module 25.

[0124] The power-on module 21 is used to receive a power-on instruction and execute a power-on strategy in response to the power-on instruction;

[0125] The temperature difference determination module 22 is used to periodically detect the average return water temperature of the parallel units after running for a preset time, and determine a first temperature difference according to the difference between the average return water temperature and a preset target temperature;

[0126] A change rate determination module 23, used to determine the temperature difference change rate according to the difference between the first temperature difference and the second temperature difference, where the second temperature difference is the first temperature difference determined in the previous cycle;

[0127] The strategy determination module 24 is used to determine the startup quantity control strategy and the frequency control strategy according to the first temperature difference and the temperature difference change rate and the preset control relationship. The startup quantity control strategy includes the full-start control strategy, the constant temperature startup control strategy, the increase control strategy, the reduction control strategy and the maintenance strategy. The frequency control strategy includes the full PID frequency regulation strategy, the fixed single PID frequency regulation strategy, the fixed single fixed frequency control strategy, the maintenance frequency strategy and the shutdown strategy;

[0128] The control module 25 is used to control the start and stop of the compressor of the corresponding heat pump unit according to the startup quantity control strategy, and adjust the frequency of the currently turned on compressor according to the frequency control strategy.

[0129] In one embodiment, the power-on module 21 includes: an instruction receiving submodule, a first temperature difference determining submodule, a power-on submodule, and a frequency regulating submodule;

[0130] The command receiving submodule is used to receive a startup command, and detect the average return water temperature of the parallel units in response to the startup command;

[0131] A first temperature difference determination submodule, used to determine a first temperature difference according to a difference between an average return water temperature and a preset target temperature;

[0132] A startup submodule, used to control a first number of compressors of heat pump units to start when the first temperature difference is greater than a first preset threshold value in a cooling mode or when the first temperature difference is less than a second preset threshold value in a heating mode, where the first number is the total number of parallel units minus one;

[0133] The frequency control submodule is used to control the frequency of the compressor according to the preset PID frequency regulation strategy of each currently turned on heat pump unit.

[0134] In one embodiment, the strategy determination module 24 includes: a first dimension parameter determination submodule, a second dimension parameter determination submodule, and a control strategy determination submodule;

[0135] A first dimension parameter determination submodule, used to determine the first dimension parameter according to the first temperature difference and a preset comparison relationship;

[0136] A second dimension parameter determination submodule, used to determine the second dimension parameter according to the temperature difference change rate and a preset comparison relationship;

[0137] The control strategy determination submodule is used to determine the startup quantity control strategy and the frequency control strategy according to the intersection of the first dimension parameter and the second dimension parameter.

[0138] In one embodiment, the first dimension parameter determination submodule includes: a temperature difference interval preset unit, a target temperature difference interval determination unit and a first dimension parameter determination unit;

[0139] A temperature difference interval preset unit, used for presetting a temperature difference interval, wherein a first preset comparison relationship exists between the temperature difference interval and a first dimension parameter;

[0140] a target temperature difference interval determination unit, configured to compare the first temperature difference with the temperature difference interval and determine a target temperature difference interval corresponding to the first temperature difference;

[0141] A first dimension parameter determination unit, used to determine a first dimension parameter corresponding to a target temperature difference range according to a first preset comparison relationship;

[0142] The second dimension parameter determination submodule includes: a temperature difference change rate interval preset unit, a target temperature difference change rate interval determination unit, and a second dimension parameter determination unit;

[0143] A temperature difference change rate interval preset unit, used to preset a temperature difference change rate interval, where the temperature difference change rate interval has a second preset comparison relationship with the second dimension parameter;

[0144] A target temperature difference change rate interval determination unit, used for comparing the temperature difference change rate with the temperature difference change rate interval, and determining a target temperature difference change rate interval corresponding to the temperature difference change rate;

[0145] The second dimension parameter determination unit is used to determine the second dimension parameter corresponding to the target temperature difference change rate interval according to the second preset comparison relationship.

[0146] In one embodiment, the control strategy determination submodule includes: a first control unit, a second control unit, a third control unit, a fourth control unit, a fifth control unit, and a sixth control unit;

[0147] A first control unit is used to determine that the startup quantity control strategy is a full-on control strategy, and to determine that the frequency control strategy is a full PID frequency regulation strategy when the first dimension parameter is within a first parameter range;

[0148] The second control unit is used to determine that the startup quantity control strategy is an additional machine control strategy, and determine that the frequency control strategy is a full PID frequency regulation strategy when the first dimension parameter is within the second parameter range and the second dimension parameter is within the third parameter range;

[0149] A third control unit is used to determine that the startup control strategy is an additional machine control strategy, and determine that the frequency control strategy is a fixed single PID frequency control strategy when the first dimension parameter is within the fourth parameter range and the second dimension parameter is within the fifth parameter range;

[0150] The fourth control unit is used to determine that the startup quantity control strategy is a maintenance strategy and the frequency control strategy is a fixed single-unit fixed frequency control strategy when the first dimension parameter is within the sixth parameter range and the second dimension parameter is within the seventh parameter range;

[0151] a fifth control unit, for determining, when the first dimension parameter is within the eighth parameter range and the second dimension parameter is within the ninth parameter range, that the startup quantity control strategy is a reduction control strategy, and determining that the frequency control strategy is a full PID frequency regulation strategy;

[0152] The sixth control unit is used to determine that the frequency control strategy is a shutdown strategy when the first dimension parameter is within the tenth parameter range, and the shutdown strategy is used to control all compressors to shut down.

[0153] In one embodiment, the heat pump unit parallel operation control device further includes: a frequency detection module;

[0154] A frequency detection module, used to detect the current operating frequency of the compressor of the currently turned-on heat pump unit;

[0155] The control module 25 includes: a power-on control submodule and a frequency control submodule;

[0156] The startup control submodule is used to start a compressor of a heat pump unit according to the additional control strategy when the current operating frequency meets the preset first condition. The preset first condition is that the current operating frequency of all the currently turned on heat pump units reaches the preset maximum frequency, limit frequency or limit high frequency and lasts for a first preset time;

[0157] The frequency control submodule is used to control the frequency of the newly-activated compressor according to its own preset PID frequency regulation strategy, and to control the operating frequency of other currently activated compressors to reduce the preset fixed frequency.

[0158] In one embodiment, based on the above implementation, the frequency detection module is further used to detect the current operating frequency of the compressor of the currently turned-on heat pump unit;

[0159] The startup control submodule is also used to shut down the compressor of a heat pump unit according to the reduction control strategy when the current operating frequency meets the preset second condition. The preset second condition is that the current operating frequency of all currently turned on heat pump units reaches a preset minimum frequency or is below the limited low frequency.

[0160] The heat pump unit parallel operation control device provided in the embodiment of the present application can be used to execute the heat pump unit parallel operation control method provided in the above embodiment, and has corresponding functions and beneficial effects.

[0161] The present application embodiment provides a heat pump unit parallel operation control device, referring to Figure 3 The heat pump unit parallel operation control device includes: a processor 31, a memory 32, a communication module 33, an input device 34 and an output device 35. The number of processors in the heat pump unit parallel operation control device can be one or more, and the number of memories in the heat pump unit parallel operation control device can be one or more. The processor, memory, communication module, input device and output device of the heat pump unit parallel operation control device can be connected through a bus or other methods.

[0162] The memory 32, as a computer-readable storage medium, can be used to store software programs, computer executable programs and modules, such as the program instructions / modules corresponding to the heat pump unit parallel operation control method described in any embodiment of the present application (for example, the startup module, temperature difference determination module, change rate determination module, strategy determination module and control module in the heat pump unit parallel operation control device). The memory may mainly include a program storage area and a data storage area, wherein the program storage area may store an operating system and at least one application required for a function; the data storage area may store data created according to the use of the device, etc. In addition, the memory may include a high-speed random access memory, and may also include a non-volatile memory, such as at least one disk storage device, a flash memory device or other non-volatile solid-state storage device. In some instances, the memory may further include a memory remotely arranged relative to the processor, and these remote memories may be connected to the device via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network and a combination thereof.

[0163] The communication module 33 is used for data transmission.

[0164] The processor 31 executes various functional applications and data processing of the device by running the software programs, instructions and modules stored in the memory, that is, realizes the above-mentioned heat pump unit parallel operation control method.

[0165] The input device 34 may be used to receive input digital or character information and generate key signal input related to user settings and function control of the device. The output device 35 may include a display device such as a display screen.

[0166] The heat pump unit parallel operation control device provided above can be used to execute the heat pump unit parallel operation control method provided in the above embodiment, and has corresponding functions and beneficial effects.

[0167] The embodiment of the present application also provides a storage medium storing computer executable instructions, wherein the computer executable instructions are used to execute a method for controlling the parallel operation of heat pump units when executed by a computer processor, and the method for controlling the parallel operation of heat pump units includes: receiving a startup instruction, responding to the startup instruction, and executing a startup strategy; after running for a first preset time, periodically detecting the average return water temperature of the parallel units, and determining a first temperature difference according to the difference between the average return water temperature and a preset target temperature; determining a temperature difference change rate according to the difference between the first temperature difference and the second temperature difference, wherein the second temperature difference is the temperature difference determined in the previous cycle. The first temperature difference; according to the first temperature difference, the temperature difference change rate and the preset control relationship, determine the startup quantity control strategy and the frequency control strategy, the startup quantity control strategy includes the full-open control strategy, the constant temperature startup control strategy, the increase machine control strategy, the reduction machine control strategy and the maintenance strategy, the frequency control strategy includes the full PID frequency regulation strategy, the fixed single PID frequency regulation strategy, the fixed single fixed frequency control strategy, the maintenance frequency strategy and the shutdown strategy; according to the startup quantity control strategy, the start and stop of the compressor of the corresponding heat pump unit is controlled, and the frequency of the currently turned on compressor is adjusted according to the frequency control strategy.

[0168] Storage medium - any of various types of memory devices or storage devices. The term "storage medium" is intended to include: installation media, such as CD-ROM, floppy disk or tape device; computer system memory or random access memory, such as DRAM, DDR RAM, SRAM, EDO RAM, Rambus RAM, etc.; non-volatile memory, such as flash memory, magnetic media (such as hard disk or optical storage); registers or other similar types of memory elements, etc. Storage media may also include other types of memory or combinations thereof. In addition, the storage medium may be located in the first computer system in which the program is executed, or may be located in a different second computer system, which is connected to the first computer system via a network (such as the Internet). The second computer system can provide program instructions to the first computer for execution. The term "storage medium" may include two or more storage media residing in different locations (for example, in different computer systems connected by a network). The storage medium may store program instructions (for example, embodied as a computer program) that can be executed by one or more processors.

[0169] Of course, the computer executable instructions of a storage medium storing computer executable instructions provided in an embodiment of the present application are not limited to the parallel operation control method of the heat pump units described above, and can also execute related operations in the parallel operation control method of the heat pump units provided in any embodiment of the present application.

[0170] The heat pump unit parallel operation control device, storage medium and heat pump unit parallel operation control equipment provided in the above embodiments can execute the heat pump unit parallel operation control method provided in any embodiment of the present application. For technical details not described in detail in the above embodiments, please refer to the heat pump unit parallel operation control method provided in any embodiment of the present application.

[0171] The above are only preferred embodiments of the present application and the technical principles used. The present application is not limited to the specific embodiments described herein, and various obvious changes, readjustments and substitutions that can be made by those skilled in the art will not deviate from the scope of protection of the present application. Therefore, although the present application is described in more detail through the above embodiments, the present application is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present application, and the scope of the present application is determined by the scope of the claims.

Claims

1. A method for controlling parallel operation of heat pump units, characterized in that: For a parallel unit, the parallel unit is composed of a plurality of heat pump units connected in parallel, the method comprising: receiving a power-on instruction, and executing a power-on strategy in response to the power-on instruction; After running for a first preset time, periodically detecting the average return water temperature of the parallel units, and determining a first temperature difference according to the difference between the average return water temperature and a preset target temperature; Determine the temperature difference change rate according to the difference between the first temperature difference and the second temperature difference, wherein the second temperature difference is the first temperature difference determined in the previous cycle; According to the first temperature difference, the temperature difference change rate and the preset control relationship, determine the startup quantity control strategy and the frequency control strategy, the startup quantity control strategy includes the full-start control strategy, the constant temperature startup control strategy, the increase control strategy, the reduction control strategy and the maintenance strategy, and the frequency control strategy includes the full PID frequency modulation strategy, the fixed single PID frequency modulation strategy, the fixed single fixed frequency control strategy, the maintenance frequency strategy and the shutdown strategy; The start and stop of the compressor of the corresponding heat pump unit is controlled according to the startup quantity control strategy, and the frequency of the currently turned-on compressor is adjusted according to the frequency control strategy.

2. The method according to claim 1, characterized in that The receiving a power-on instruction and executing a power-on strategy in response to the power-on instruction includes: receiving a startup instruction, and detecting an average return water temperature of the parallel unit in response to the startup instruction; Determining a first temperature difference according to a difference between the average return water temperature and a preset target temperature; When in cooling mode and the first temperature difference is greater than a first preset threshold value or when in heating mode and the first temperature difference is less than a second preset threshold value, controlling a first number of compressors of the heat pump units to start, the first number being the total number of the parallel units minus one; The frequency of the compressor is controlled according to the preset PID frequency regulation strategy of each heat pump unit currently turned on.

3. The method according to claim 1, characterized in that The determining of the startup quantity control strategy and the frequency control strategy according to the first temperature difference, the temperature difference change rate and a preset control relationship includes: Determining a first dimension parameter according to the first temperature difference and a preset comparison relationship; Determining a second dimension parameter according to the temperature difference change rate and a preset comparison relationship; The startup quantity control strategy and the frequency control strategy are determined according to the intersection of the first dimension parameter and the second dimension parameter.

4. The method according to claim 3, characterized in that The determining of the first dimension parameter according to the first temperature difference and a preset comparison relationship includes: A preset temperature difference interval, wherein the temperature difference interval has a first preset comparison relationship with the first dimension parameter; Comparing the first temperature difference with the temperature difference interval to determine a target temperature difference interval corresponding to the first temperature difference; Determine a first dimension parameter corresponding to the target temperature difference range according to a first preset comparison relationship; Determining the second dimension parameter according to the temperature difference change rate and a preset comparison relationship includes: A preset temperature difference change rate interval, wherein the temperature difference change rate interval has a second preset comparison relationship with the second dimension parameter; Comparing the temperature difference change rate with the temperature difference change rate interval, and determining a target temperature difference change rate interval corresponding to the temperature difference change rate; The second dimension parameter corresponding to the target temperature difference change rate interval is determined according to the second preset comparison relationship.

5. The method according to claim 3, characterized in that: The determining the startup quantity control strategy and the frequency control strategy according to the intersection of the first dimension parameter and the second dimension parameter includes: When the first dimension parameter is within the first parameter range, determining the startup quantity control strategy to be the full-on control strategy, and determining the frequency control strategy to be the full PID frequency regulation strategy; When the first dimension parameter is within the second parameter range, and the second dimension parameter is within the third parameter range, determining the startup quantity control strategy to be the additional machine control strategy, and determining the frequency control strategy to be the full PID frequency regulation strategy; When the first dimension parameter is within the fourth parameter range, and the second dimension parameter is within the fifth parameter range, determining that the startup control strategy is the additional machine control strategy, and determining that the frequency control strategy is the fixed single PID frequency control strategy; When the first dimension parameter is within the sixth parameter range, and the second dimension parameter is within the seventh parameter range, determining the startup quantity control strategy to be the maintenance strategy, and determining the frequency control strategy to be the fixed single-unit fixed frequency control strategy; When the first dimension parameter is within the eighth parameter range, and the second dimension parameter is within the ninth parameter range, determining the startup quantity control strategy to be the reduction control strategy, and determining the frequency control strategy to be the full PID frequency regulation strategy; When the first dimension parameter is within the tenth parameter range, the frequency control strategy is determined to be the shutdown strategy, and the shutdown strategy is used to control all compressors to shut down.

6. The method according to claim 5, characterized in that When the first dimension parameter is within the second parameter range, and the second dimension parameter is within the third parameter range, after determining that the startup quantity control strategy is the additional machine control strategy, and determining that the frequency control strategy is the full PID frequency regulation strategy, the method includes: Detect the current operating frequency of the compressor of the currently turned-on heat pump unit; The method of controlling the start and stop of the compressor of the corresponding heat pump unit according to the startup quantity control strategy includes: According to the additional machine control strategy, when the current operating frequency meets the preset first condition, a compressor of a heat pump unit is newly turned on, and the preset first condition is that the current operating frequency of all the currently turned on heat pump units reaches the preset maximum frequency, limit frequency or limit high frequency, and lasts for a first preset time; The newly-activated compressor is controlled to perform frequency regulation according to its own preset PID frequency regulation strategy, and the operating frequency of other currently activated compressors is controlled to be reduced by a preset fixed frequency.

7. The method according to claim 5, characterized in that When the first dimension parameter is within the eighth parameter range and the second dimension parameter is within the ninth parameter range, after determining that the startup quantity control strategy is the reduction control strategy and determining that the frequency control strategy is the full PID frequency regulation strategy, the method further comprises: Detect the current operating frequency of the compressor of the currently turned-on heat pump unit; The method of controlling the start and stop of the compressor of the corresponding heat pump unit according to the startup quantity control strategy includes: According to the machine reduction control strategy, when the current operating frequency meets the preset second condition, the compressor of a heat pump unit is turned off, and the preset second condition is that the current operating frequency of all currently turned on heat pump units reaches the preset minimum frequency or is below the limited low frequency.

8. A heat pump unit parallel operation control device, characterized in that: Used for a parallel unit, the parallel unit is composed of multiple heat pump units connected in parallel, the device includes: A power-on module, configured to receive a power-on instruction and execute a power-on strategy in response to the power-on instruction; A temperature difference determination module, used for periodically detecting the average return water temperature of the parallel units after running for a preset time, and determining a first temperature difference according to the difference between the average return water temperature and a preset target temperature; a change rate determination module, configured to determine a temperature difference change rate according to a difference between the first temperature difference and a second temperature difference, wherein the second temperature difference is the first temperature difference determined in a previous cycle; a strategy determination module, for determining a startup quantity control strategy and a frequency control strategy according to the first temperature difference, the temperature difference change rate and a preset control relationship, wherein the startup quantity control strategy includes a full-start control strategy, a constant temperature startup control strategy, an increase machine control strategy, a reduction machine control strategy and a maintenance strategy, and the frequency control strategy includes a full PID frequency modulation strategy, a fixed single PID frequency modulation strategy, a fixed single fixed frequency control strategy, a maintenance frequency strategy and a shutdown strategy; The control module is used to control the start and stop of the compressor of the corresponding heat pump unit according to the startup quantity control strategy, and to adjust the frequency of the currently turned on compressor according to the frequency control strategy.

9. A heat pump unit parallel operation control device, characterized in that: include: memory and one or more processors; The memory is used to store one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors implement the method according to any one of claims 1 to 7.

10. A storage medium storing computer executable instructions, characterized in that: The computer executable instructions are used to perform the method according to any one of claims 1 to 7 when executed by a processor.

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