A self-control method and system for a water pump direct control of a fixed-frequency air-cooled heat pump refrigeration system

Abstract

The application discloses a kind of self-control method and system of fixed frequency air-cooled heat pump refrigeration system water pump direct control, belong to air conditioning system automatic control technical field, comprising: obtaining the operating state parameter of system, according to operating state parameter to construct operating state dataset;Real-time cooling load demand of current system is calculated;The current operating current of compressor is calculated with the current ratio of rated current, determine whether the operating state of compressor is effective;According to real-time cooling load demand, the operating state of compressor calculates water pump demand coefficient, according to water pump demand coefficient to determine whether to meet the starting or stopping condition of water pump, when continuously meeting starting or stopping condition, output start-stop instruction.In prior art, a large number of DDC control points need to be configured, which is costly and labor-intensive.On the other hand, compared with prior art, the present application controls the water pump and the compressor in linkage, effectively reducing the number of control points, reducing the workload while reducing the cost of compression.

Description

Technical Field

[0001] This invention relates to the field of automatic control technology for air conditioning systems, and in particular to an automatic control method and system for direct control of water pumps in a fixed-frequency air-cooled heat pump refrigeration system. Background Technology

[0002] In the automation design of modern building central air conditioning systems, direct digital controllers (DDCs) are typically used for centralized control of equipment such as compressors and pumps. Traditional designs require assigning independent control points (including digital inputs (DI), digital outputs (DO), analog inputs (AI), and analog outputs (AO)) to each controlled device to achieve precise start-up, shutdown, adjustment, and monitoring. Each control point corresponds to a DDC hardware module, wiring, and programming / debugging work. Current automation designs have the following drawbacks: 1. High cost: The more locations there are, the higher the initial investment cost of the system (including hardware procurement and installation); 2. Large workload for design and debugging: The large number of points makes the control system logic more complex, and the programming and on-site installation and debugging cycle is long.

[0003] The above content is only used to help understand the technical solution of the present invention and does not represent an admission that the above content is prior art. Summary of the Invention

[0004] This invention provides an automatic control method for direct control of water pump in a fixed-frequency air-cooled heat pump refrigeration system, comprising: S1: acquiring the system's operating status parameters and constructing an operating status dataset based on the operating status parameters; S2: Calculate the real-time cooling load demand of the current system based on the operating status parameters; S3: Calculate the ratio of the compressor's current operating current to its rated current, calculate the temperature deviation between the evaporation temperature and the set value, and determine whether the compressor's operating status is effective based on the current ratio and temperature deviation. S4: Calculate the water pump demand coefficient based on real-time cooling load demand and compressor operating status, and determine whether the water pump start-up or stop conditions are met based on the water pump demand coefficient. S5: When the pump demand coefficient continuously meets the start or stop conditions within the set sampling period, output start / stop command.

[0005] Furthermore, the runtime status dataset is as follows:

[0006] The water supply temperature for the unit; This refers to the return water temperature of the unit. Ambient temperature; This is the condensation pressure; This is the evaporation pressure; It is the volumetric flow rate of water; This is the compressor operating current.

[0007] Furthermore, S2 also includes the following steps: The real-time cooling load requirement is calculated as follows:

[0008] The system's real-time cooling load demand at time t; The specific heat capacity at constant pressure for circulating water; The density of the circulating water; Let t be the water volumetric flow rate at time t; Let be the unit return water temperature at time t; Let t be the unit's water supply temperature at time t.

[0009] Furthermore, the operating status of the compressor is determined as follows:

[0010] Let t be the compressor operating current; This refers to the compressor's rated current. This is the operating current threshold coefficient; Let t be the evaporation temperature at time t; Set the evaporation temperature value; This is the allowable deviation threshold for evaporation temperature; when When the value is 1, the compressor is determined to be in effective operation. when When the value is 0, the compressor is determined to be ineffective.

[0011] Furthermore, the pump demand factor is calculated as follows:

[0012] This refers to the rated cooling capacity of the unit; This is a correction factor for ambient temperature. This is a reference value for ambient temperature. Let t be the ambient temperature at time t; when At that time, the water pump is triggered to start; when When this happens, the water pump stops. This is the water pump start-up threshold.

[0013] Furthermore, S5 also includes the following steps:

[0014] It is an indicator function; To prevent shaking, confirm the window length; The number of sampling points required to initiate confirmation; To stop confirming the number of sampling points that need to meet the required conditions; This is the current sampling time; This is the sampling time offset; when When the value is 1, the start command is output; when When the value is 0, a stop command is output.

[0015] Furthermore, it also includes step S6; S6 includes the following steps: Control the output voltage according to the start / stop command:

[0016] The DC power supply voltage for the built-in control box.

[0017] Furthermore, it also includes step S7; S7 includes the following steps: Acquire the status signal fed back by the water pump and compare the status signal with the start / stop command; When the status signal matches the start / stop command, the status information is reported; When the status signal is inconsistent with the start / stop command, a fault alarm signal is output and the status information is reported.

[0018] The present invention also provides an automatic control system for direct control of the water pump in a fixed-frequency air-cooled heat pump refrigeration system, using the method described above.

[0019] Compared with the prior art, the present invention has the following advantages: This invention can transform the control logic of the water pump from direct control by DDC to linkage control by the built-in controller of the air-cooled heat pump unit based on the compressor's operating status. This significantly reduces the number of direct control points at the DDC control level, thereby reducing the overall system cost and simplifying engineering implementation.

[0020] This invention constructs a multi-parameter fusion criterion that also considers real-time cooling load requirements. Compressor operating status Ambient temperature Compared to a single criterion (such as relying solely on the compressor start / stop signal), this invention allows for more precise pump start / stop decisions. For example, when the compressor has just started but the load has not yet been established, conventional methods might immediately start the water pump, resulting in wasted energy. However, this invention... Continuous calculations can effectively avoid such erroneous actions.

[0021] This invention is achieved through , , The coordinated configuration of the three parameters constructs a delay confirmation and anti-jitter processing mechanism, ensuring that start / stop commands are only output when conditions are met for multiple consecutive sampling periods. With a sampling period of 2 seconds... =10、 Taking a value of 5 as an example, the water pump will only start after meeting the starting conditions for at least 10 consecutive seconds. This effectively filters out interference caused by parameter fluctuations. Furthermore, it effectively avoids frequent pump starts and stops due to small fluctuations in a short period, which would severely shorten the motor's lifespan.

[0022] This invention introduces an ambient temperature correction term. This makes the water pump demand factor It can automatically adjust according to the ambient temperature. When the ambient temperature is higher than the designed ambient temperature reference value, the water pump demand factor... It can automatically adjust to ensure heat exchange efficiency. When the ambient temperature is low, the pump demand factor... It can automatically reduce energy consumption and avoid unnecessary energy consumption.

[0023] This invention does not affect the control logic when replacing water pumps or units, and can be connected via a standardized 24VDC linkage interface, thus eliminating the need to modify the DDC hardware configuration or software program. This significantly reduces the complexity of system operation and maintenance. Attached Figure Description

[0024] Figure 1 Overall process diagram. Detailed Implementation

[0025] It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0026] Example 1: This invention provides an automatic control method for direct control of the water pump in a fixed-frequency air-cooled heat pump refrigeration system, referring to... Figure 1 , Figure 1 This is a schematic diagram of the process of the present invention. It includes: S1: Obtaining the system's operating status parameters, and constructing an operating status dataset based on the operating status parameters.

[0027] The water supply temperature for the unit is collected by a water supply temperature sensor. The return water temperature of the unit is collected by the return water temperature sensor. The ambient temperature is collected by an outdoor ambient temperature sensor. The condensation pressure is collected by the condenser-side pressure sensor. The evaporation pressure is collected by the evaporation-side pressure sensor. The volumetric flow rate is collected by a flow meter. The compressor operating current is collected by a current transformer.

[0028] S2: Based on the collected unit return water temperature Unit water supply temperature Calculate the real-time cooling load requirement of the current system:

[0029] The system's real-time cooling load demand at time t; The specific heat capacity at constant pressure for circulating water; The density of the circulating water; Let t be the water volumetric flow rate at time t; Let be the unit return water temperature at time t; Let t be the unit's water supply temperature at time t.

[0030] S3: Calculate the ratio of the compressor's current operating current to its rated current, calculate the temperature deviation between the evaporating temperature and the set value, and determine whether the compressor's operating status is effective based on the current ratio and temperature deviation.

[0031] Let be the compressor operating current at time t; This is the compressor's rated current. This value can be obtained from the equipment nameplate. This is the operating current threshold coefficient. Preferably, the value ranges from 0.65 to 0.85, with a default value of 0.75. The evaporation temperature at time t can be obtained from the evaporation pressure obtained in step S1. Obtained by conversion using a saturation temperature table; The evaporation temperature setpoint is determined by the design parameters of the central air conditioning system; This is the allowable deviation threshold for evaporation temperature. Preferably, the value ranges from 1.0 to 3.0, with a default value of 2.0. when When the value is 1, the compressor is determined to be in effective operation. when When the value is 0, the compressor is determined to be ineffective.

[0032] S4: Real-time cooling load demand calculated based on S2 The operating status of the compressor calculated by S3 Calculate the water pump demand factor:

[0033] The rated cooling capacity of the unit is obtained from the equipment's nameplate. The ambient temperature correction factor is preferably set to 0.05~0.15, with a default value of 0.10. As a reference value for ambient temperature, and preferably, the operating ambient temperature of the central air conditioning system design is 35℃. Let t be the ambient temperature at time t; when At that time, the water pump is triggered to start; when When this happens, the water pump stops. The water pump start-up threshold is preferably set to a value between 0.10 and 0.25, with a default value of 0.15.

[0034] In summary, through the aforementioned process, this invention constructs a multi-parameter fusion criterion that also considers real-time cooling load requirements. Compressor operating status Ambient temperature Compared to a single criterion (such as relying solely on the compressor start / stop signal), this invention allows for more precise pump start / stop decisions. For example, when the compressor has just started but the load has not yet been established, conventional methods might immediately start the water pump, resulting in wasted energy. However, this invention... Continuous calculations can effectively avoid such erroneous actions.

[0035] On the other hand, the present invention introduces an ambient temperature correction term. This makes the water pump demand factor It can automatically adjust according to the ambient temperature. When the ambient temperature is higher than the designed ambient temperature reference value, the water pump demand factor... It can automatically adjust to ensure heat exchange efficiency. When the ambient temperature is low, the pump demand factor... It can automatically reduce energy consumption and avoid unnecessary energy consumption.

[0036] S5: To prevent frequent pump start-stop due to signal fluctuations, adjust the pump demand coefficient obtained from S4. Delay confirmation and anti-vibration processing are implemented. When the pump demand coefficient continuously meets the start or stop conditions within the set sampling period, a start / stop command is output. Details are as follows:

[0037] The start / stop command from the previous moment; It is an indicator function; The pump demand coefficient for the first i sampling times; For the anti-shake confirmation window length, the preferred value is 5~20, with a default value of 10. The number of sampling points required to initiate confirmation is preferably 3 to 10, with a default value of 5. To stop confirming the required number of sampling points that meet the conditions, the preferred value is 3 to 10, with a default value of 5. This is the current sampling time; This is the sampling time offset; The constraints are: , specifically and The value can be pre-configured according to the actual response speed requirements; when When the value is 1, the start command is output; when When the value is 0, a stop command is output.

[0038] In summary, this invention achieves... , , The coordinated configuration of the three parameters constructs a delay confirmation and anti-jitter processing mechanism, ensuring that start / stop commands are only output when conditions are met for multiple consecutive sampling periods. With a sampling period of 2 seconds... =10、 Taking a value of 5 as an example, the water pump will only start after meeting the starting conditions for at least 10 consecutive seconds. This effectively filters out interference caused by parameter fluctuations. Furthermore, it effectively avoids frequent pump starts and stops due to small fluctuations in a short period, which would severely shorten the motor's lifespan.

[0039] S6: Based on S5 The corresponding electrical signal is output to the 24VDC linkage relay in the built-in control box, as follows:

[0040] in, The DC power supply voltage for the built-in control box.

[0041] Therefore, when hour, The relay is activated, the AC contactor coil is energized, and the water pump starts.

[0042] when hour, The relay is released, the AC contactor coil is de-energized, and the water pump stops.

[0043] S7: Obtain the status signal from the water pump and compare the status signal with the start / stop command; When the status signal matches the start / stop command, the status information is reported; When the status signal is inconsistent with the start / stop command, a fault alarm signal is output and the status information is reported.

[0044] Specifically as follows:

[0045]

[0046] in, The value of the pump's state deviation at time t is -1, 0, or 1. The status signal fed back by the water pump at time t, where 1 indicates start and 0 indicates stop, is collected by the auxiliary contact of the contactor. The fault alarm flag at time t, where 1 indicates an alarm and 0 indicates normal operation; The delay time from the output of the start / stop command to the confirmation of the status signal from the water pump; The maximum allowable response delay time is preferably set to a value between 3 and 10, with a default value of 5.

[0047] when When this occurs, it indicates that the system is operating normally and will maintain its current state.

[0048] when and When this occurs, a fault alarm is triggered, and the start / stop command is re-outputted.

[0049] If three consecutive retries fail, the fault status will be reported to the cloud management platform via the communication network.

[0050] In summary, through the aforementioned process, this invention can transform the control logic of the water pump from direct control by the DDC to linkage control by the built-in controller of the air-cooled heat pump unit based on the compressor's operating status. This significantly reduces the number of direct control points at the DDC control level, thereby reducing the overall system cost and simplifying engineering implementation.

[0051] On the other hand, through the aforementioned process, the present invention does not affect the control logic when replacing water pumps or units, and can be connected via a standardized 24VDC linkage interface, thus eliminating the need to modify the hardware configuration or software program of the DDC. This significantly reduces the complexity of system operation and maintenance.

[0052] To facilitate understanding of the above calculation process, the following calculation examples are provided: Suppose that an office building is equipped with a fixed-frequency air-cooled heat pump unit with a rated cooling capacity of compressor rated current The designed operating environment temperature The controller sampling period is 2 seconds.

[0053] S1: At a certain moment, the sensors collected the following parameters: .

[0054] .

[0055] .

[0056] .

[0057] .

[0058] .

[0059] S2:

[0060] S3: Settings , , .

[0061] .

[0062] .

[0063] but .

[0064] S4: Settings , .

[0065] .

[0066] .

[0067] .

[0068] because, This triggers the water pump to start.

[0069] S5: Set the length of the anti-shake confirmation window (Total duration 20s) Initiate confirmation of the number of sampling points that meet the required conditions. The value is 5. A total of 8 cycles satisfy this condition. If the startup confirmation conditions are met, output... .

[0070] S6: The relay clicks open, and the water pump starts.

[0071] S7: Received =1, The system is operating normally.

[0072] Example 2: An automatic control system for direct control of the water pump in a fixed-frequency air-cooled heat pump refrigeration system is disclosed, employing the method described in Embodiment 1. Specifically, it includes a cloud monitoring and management layer, a network transmission layer, and a field device execution layer. The cloud monitoring and management layer deploys a cloud-based intelligent management platform to receive and store the calculation process and final output results described in Embodiment 1. It also receives instructions manually input by the operator.

[0073] The network transport layer forms the local area network backbone through Ethernet switches. Industrial gateways or protocol conversion gateways are deployed between the field network and the end devices. One end connects to the field switch via Ethernet, accessing the enterprise LAN or the Internet, while the other end connects to the various devices in the field via a fieldbus.

[0074] The field equipment execution layer includes air-cooled heat pump units, water pumps, and linkage control cables. The air-cooled heat pump units are equipped with control panels for communication with the gateway. The control box built into the air-cooled heat pump units has 24V relay control signal output terminals for compressor and water pump linkage.

[0075] The water pump control box has a reserved 24VDC control signal input interface.

[0076] The linkage control cable is laid between the air-cooled heat pump unit and the water pump to transmit 24VDC linkage signals.

[0077] Furthermore, it should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or system. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or system that includes that element.

[0078] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0079] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as read-only memory (ROM) / RAM, magnetic disk, optical disk) and includes several instructions to cause a terminal device (which may be a mobile phone, computer, server, or network device, etc.) to execute the methods described in the various embodiments of the present invention.

[0080] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural or procedural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

[0081] It is understood that the system provided in the embodiments of the present invention corresponds to the method provided in the embodiments of the present invention, and the explanation, examples and beneficial effects of the relevant content can be referred to the corresponding parts of the above methods.

Claims

1. A self-control method for direct control of the water pump in a fixed-frequency air-cooled heat pump refrigeration system, characterized in that, include: S1: Obtain the system's operating status parameters and construct an operating status dataset based on the operating status parameters; S2: Calculate the real-time cooling load demand of the current system based on the operating status parameters; S3: Calculate the ratio of the current operating current of the compressor to the rated current, calculate the temperature deviation between the evaporation temperature and the set value, and determine whether the operating status of the compressor is effective based on the current ratio and the temperature deviation. S4: Calculate the water pump demand coefficient based on the real-time cooling load demand and the compressor operating status, and determine whether the water pump start-up or stop conditions are met based on the water pump demand coefficient. S5: When the pump demand coefficient continuously meets the start or stop conditions within the set sampling period, output a start / stop command.

2. The automatic control method for direct control of the water pump in a fixed-frequency air-cooled heat pump refrigeration system as described in claim 1, characterized in that, The running status dataset is as follows: The The water supply temperature for the unit; The This refers to the return water temperature of the unit. The The ambient temperature; The This is the condensation pressure; The This is the evaporation pressure; The It is the volumetric flow rate of water; The This is the compressor operating current.

3. The automatic control method for direct control of the water pump in a fixed-frequency air-cooled heat pump refrigeration system as described in claim 1, characterized in that, S2 further includes the following steps: The real-time cooling load requirement is calculated as follows: The The system's real-time cooling load demand at time t; The The specific heat capacity at constant pressure for circulating water; The The density of the circulating water; The Let t be the water volumetric flow rate at time t; The Let be the unit return water temperature at time t; The Let t be the unit's water supply temperature at time t.

4. The automatic control method for direct control of the water pump in a fixed-frequency air-cooled heat pump refrigeration system as described in claim 1, characterized in that, The operating status of the compressor is determined as follows: The Let be the compressor operating current at time t; The This refers to the compressor's rated current. The This is the operating current threshold coefficient; The Let t be the evaporation temperature at time t; The Set the evaporation temperature value; The This is the allowable deviation threshold for evaporation temperature; When the When the value is 1, the compressor is determined to be in effective operation. When the When the value is 0, the compressor is determined to be in an ineffective operating state.

5. The automatic control method for direct control of the water pump in a fixed-frequency air-cooled heat pump refrigeration system as described in claim 1, characterized in that, The pump demand factor is calculated as follows: The This refers to the rated cooling capacity of the unit. The This is a correction factor for ambient temperature. The This is a reference value for ambient temperature. The Let t be the ambient temperature at time t; when When this occurs, the water pump is triggered to start; when When this occurs, the water pump is triggered to stop; The This is the water pump start-up threshold.

6. The automatic control method for direct control of the water pump in a fixed-frequency air-cooled heat pump refrigeration system as described in claim 1, characterized in that, S5 further includes the following steps: The It is an indicator function; The To prevent shaking, confirm the window length; The The number of sampling points required to initiate confirmation; The To stop confirming the number of sampling points that need to meet the required conditions; The This is the current sampling time; The This is the sampling time offset; When the When the value is 1, the start command is output; When the When the value is 0, a stop command is output.

7. The automatic control method for direct control of the water pump in a fixed-frequency air-cooled heat pump refrigeration system as described in claim 1, characterized in that, It also includes step S6; S6 includes the following steps: Control the output voltage according to the start / stop command: The The DC power supply voltage for the built-in control box.

8. The automatic control method for direct control of the water pump in a fixed-frequency air-cooled heat pump refrigeration system as described in claim 1, characterized in that, It also includes step S7; S7 includes the following steps: Obtain the status signal fed back by the water pump, and compare the status signal with the start / stop command; When the status signal matches the start / stop command, the status information is reported; When the status signal is inconsistent with the start / stop command, a fault alarm signal is output and the status information is reported.

9. An automatic control system for direct control of the water pump in a fixed-frequency air-cooled heat pump refrigeration system, characterized in that, The method described in any one of claims 1 to 8 is applied.

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