Method for controlling rotating speed of water pump in heat pump system

Abstract

The invention relates to the technical field of heat pump system control methods, in particular to a water pump rotating speed control method in a heat pump system, which comprises the following steps of: acquiring data; comprehensive load calculation: calculating a terminal load index according to the system reference rated total power and the terminal real-time total power, calculating a host output index according to the compressor rated highest frequency and the compressor real-time operation frequency, and calculating a real-time comprehensive load according to the terminal load index and the host output index; and target rotating speed calculation: calculating the target rotating speed of the water pump according to the real-time comprehensive load. According to the method, the terminal heat exchange demand can be accurately represented through the terminal load index, the host load level is reflected through the host output index, the real-time comprehensive load is calculated through weighted fusion of the terminal load index and the host output index, and it is guaranteed that the system can stably and efficiently operate under the change of the terminal load and the host strength.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heat pump system control method, more particularly, to a water pump rotating speed control method in a heat pump system. BACKGROUND

[0002] In a conventional heat pump system, the water pump is the core of circulation power, and its rotating speed adjustment strategy is directly related to the system energy efficiency, stability and operating cost. At present, the most common water pump control methods in engineering practice mainly include control based on the temperature difference between inlet and outlet water, feedback control based on flow sensor, and start-stop control depending on the end device switch signal. However, these methods have certain technical limitations, and it is difficult to achieve accurate and efficient water pump operation under dynamic load conditions.

[0003] The temperature difference control adjusts the rotating speed of the water pump by detecting the temperature difference between the inlet and outlet water of the heat exchanger, but due to the obvious delay of water temperature change, the system response is lagging, and it is difficult to match the load fluctuation in real time. Although the flow sensor control can directly monitor the flow, the sensor itself is relatively high in cost, and its measurement accuracy is easily affected by pipeline configuration, installation conditions and medium state, and its long-term reliability is insufficient, which also increases the system cost. The end switch signal control can only determine the start and stop of the device, and cannot identify the actual load, resulting in the water pump often running at high speed under partial load conditions, and the energy efficiency is low. SUMMARY

[0004] The purpose of the present application is to overcome the deficiency that the prior art is difficult to match the load fluctuation in real time, and to provide a water pump rotating speed control method in a heat pump system, which is convenient for real-time matching of actual load.

[0005] To solve the above technical problems, the technical solution adopted by the present application is: A water pump rotating speed control method in a heat pump system is provided, comprising the following steps: Data acquisition: collecting the real-time total power of the end and collecting the real-time operating frequency of the compressor, setting the system reference rated total power and the compressor rated maximum frequency; Comprehensive load calculation: calculating the end load index according to the system reference rated total power and the end real-time total power, calculating the main machine output index according to the compressor rated maximum frequency and the compressor real-time operating frequency, and calculating the real-time comprehensive load according to the end load index and the main machine output index; Target rotating speed calculation: calculating the water pump target rotating speed according to the real-time comprehensive load.

[0006] The water pump rotating speed control method in the heat pump system of the application collects the terminal real-time total power and the compressor real-time running frequency, sets the system reference rated total power and the compressor rated highest frequency; calculates the terminal load index according to the system reference rated total power and the terminal real-time total power, calculates the main machine output index according to the compressor rated highest frequency and the compressor real-time running frequency, and calculates the real-time comprehensive load according to the terminal load index and the main machine output index; finally, the water pump target rotating speed is calculated according to the real-time comprehensive load. The terminal load index can accurately represent the terminal heat exchange demand, the main machine output index can reflect the main machine load level, the real-time comprehensive load is calculated by weighting the terminal load index and the main machine output index, so that the system can keep stable and efficient operation under the change of terminal load and main machine strength.

[0007] Preferably, the collecting terminal total power specifically comprises: acquiring the running power of each terminal fan coil through a bus, and calculating the terminal total power according to the running power of each terminal fan coil.

[0008] Preferably, the bus uses a 485 bus. The RS-485 bus has the advantages of differential signal, strong anti-interference, long transmission distance, low cost, and can connect multiple nodes, and is very suitable for industrial environment.

[0009] Preferably, the terminal total power is calculated by the following formula:

[0010] wherein, P represents the terminal total power; N represents the total number of terminal fan coils; Pn represents the running power of the nth terminal fan coil.

[0011] Preferably, the terminal load index is calculated by the following formula:

[0012] wherein, I represents the terminal load index; P represents the terminal total power; I is between (0, 1); P0 represents the system reference rated total power.

[0013] Preferably, the main machine output index is calculated by the following formula:

[0014] wherein, I represents the main machine output index; f represents the compressor real-time running frequency; ​represents the compressor rated maximum frequency.

[0015] Preferably, the real-time comprehensive load is calculated by weighting and fusing the terminal load index and the host output index.

[0016] Preferably, the real-time comprehensive load is calculated by the following formula:

[0017] wherein, represents the real-time comprehensive load; represents the weight coefficient, .

[0018] Preferably, the water pump target rotating speed is calculated by the following formula:

[0019] wherein, represents the water pump target rotating speed; represents the water pump maximum operating rotating speed; represents the water pump minimum operating rotating speed.

[0020] Preferably, the system reference rated total power and the compressor rated maximum frequency can be flexibly configured according to engineering design and use scene. The adaptability of the control method is enhanced, so that the control method can be suitable for different scale applications.

[0021] Compared with the prior art, the present application has the following beneficial effects: The water pump rotating speed control method in the heat pump system of the present application can accurately represent the terminal heat exchange demand through the terminal load index, reflect the host load level through the host output index, and calculate the real-time comprehensive load by weighting and fusing the terminal load index and the host output index, so that the system can maintain stable and efficient operation under the change of terminal load and host strength. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a flowchart of the water pump rotating speed control method in the heat pump system of the present application. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all. The present application will be further described below with reference to specific embodiments. The drawings are only used for illustrative description, and the representation is only a schematic diagram, not a physical diagram, and cannot be understood as a limitation of the present patent; for those skilled in the art, it is understandable that some known structures and their descriptions in the drawings can be omitted.

[0024] Example 1 This embodiment is a first embodiment of a water pump speed control method in a heat pump system, such as... Figure 1 As shown, it includes the following steps: Data Acquisition: The system collects the real-time total power of the terminal units and the real-time operating frequency of the compressors. Specifically, the total power is obtained by using a RS-485 bus to acquire the operating power of each terminal fan coil unit. The core advantages of the RS-485 bus lie in its high versatility and cost-effectiveness. It uses differential signal transmission, has strong anti-common-mode interference capabilities, and can communicate over distances exceeding one kilometer. The bus structure is simple, supports multi-point networking with up to 32-256 nodes, and has extremely low wiring costs, making it ideal for long-distance, multi-node industrial monitoring and data acquisition systems. The total terminal power is calculated based on the operating power of each terminal fan coil unit. The system reference rated total power and the compressor's rated maximum frequency are set. These can be flexibly configured according to engineering design and usage scenarios. The system reference rated total power defines the system's baseline cooling / heating capacity under standard operating conditions, while the compressor's rated maximum frequency limits the maximum speed of its core power unit. This dual-parameter design offers high configurability, allowing parameters to be adjusted independently or in conjunction with other parameters based on specific project needs, such as building structure, insulation performance, load characteristics, and diverse application scenarios, including data center precision air conditioning, commercial buildings, and industrial process cooling. This flexibility ensures a precise match between system capacity and actual load, thereby maximizing energy efficiency and operational reliability while guaranteeing optimal performance. It also enhances the adaptability of the control method, making it suitable for applications of different scales.

[0025] Comprehensive load calculation: The terminal load index is calculated based on the system reference rated total power and the terminal real-time total power, and the main unit output index is calculated based on the compressor rated maximum frequency and the compressor real-time operating frequency. The real-time comprehensive load is calculated by weighting and fusing the terminal load index and the main unit output index. Target speed calculation: The target speed of the water pump is calculated based on the real-time comprehensive load.

[0026] The working process of the water pump speed control method in a heat pump system according to this embodiment is as follows: The system collects the real-time total power at the terminal and the real-time operating frequency of the compressor, sets the system reference rated total power and the compressor rated maximum frequency, calculates the terminal load index based on the system reference rated total power and the real-time total power at the terminal, calculates the main unit output index based on the compressor rated maximum frequency and the compressor real-time operating frequency, calculates the real-time comprehensive load based on the terminal load index and the main unit output index, and finally calculates the target speed of the water pump based on the real-time comprehensive load.

[0027] The most common water pump control methods in engineering practice mainly include control based on the temperature difference between inlet and outlet water, feedback control based on flow sensor, and start-stop control relying on the switch signal of terminal equipment. However, the temperature difference control adjusts the water pump speed by detecting the temperature difference between the inlet and outlet of the heat exchanger, but due to the obvious delay of water temperature change, the system response is lagging, and it is difficult to match the load fluctuation in real time. Although the flow sensor control can directly monitor the flow, the sensor itself is high in cost, and its measurement accuracy is easily affected by pipeline configuration, installation conditions and medium state, and its long-term reliability is insufficient, which also increases the system cost. The terminal switch signal control can only determine the start and stop of the equipment, and cannot identify the actual load level, resulting in the water pump still running at high speed under partial load conditions, which is low in energy efficiency. The present application calculates the comprehensive load index by real-time collection of terminal power and combination of compressor frequency normalization, and determines the target speed of the water pump according to the comprehensive load index. The terminal load index can accurately represent the terminal heat exchange demand, the host output index can reflect the host load level, and the real-time comprehensive load can be calculated by weighted fusion of the terminal load index and the host output index, which can not only reflect the real load of the terminal, but also reflect the running strength of the host, so as to accurately reflect the actual working condition, improve the coordination and energy efficiency of the system, and ensure that the system can maintain stable and efficient operation under the change of terminal load and host strength.

[0028] Embodiment two This embodiment is a second embodiment of the water pump speed control method in the heat pump system. Based on embodiment one, in this embodiment, the total terminal power is calculated by the following formula:

[0029] Among them, represents the total terminal power; represents the total number of terminal fan coils; represents the running power of the i-th terminal fan coil.

[0030] ​That is, the total power of the terminal is regarded as the sum of the running power of all terminal fan-coil units at a certain moment. Since each fan-coil unit is an independent electrical equipment, its power consumption mainly includes the power consumption of the fan motor and the electric auxiliary heating (if it is an electric heating type). According to the basic principle of electric circuit, in a parallel circuit, the total power is equal to the sum of the load power of each branch. The power supply system of the entire air conditioning terminal is a huge parallel circuit. Therefore, the total power read from the ammeter or smart meter of the distribution box is essentially the cumulative value of the power of all running fan-coil units. The start-stop and speed (high, medium, low) of the fan-coil unit are controlled by the user or the building automatic control system. The most direct method for the system control center to understand the "real-time total demand" of the entire terminal is to summarize the running state of all terminals. Adding the instantaneous power (or the power estimated according to the running gear) of each terminal can obtain the total energy consumption demand of the terminal. The sum of the running power of the terminal directly reflects the total demand load of the entire building at the current moment. Let the operation strategy of the water pump be adjusted according to the total power of the terminal to realize energy-saving operation at low load and ensure energy supply effect at high load, improve comfort and efficiency.

[0031] The terminal load index is calculated by the following formula:

[0032] wherein, represents the terminal load index; represents between (0, 1); represents the system reference rated total power.

[0033] The host output index is calculated by the following formula:

[0034] wherein, represents the host output index; represents the real-time running frequency of the compressor; represents the rated maximum frequency of the compressor.

[0035] By setting the terminal load index and the host output index, the original data of the terminal total power and the real-time running frequency of the compressor are normalized. This step aims to map physical quantities with different dimensions and orders of magnitude to a specific numerical interval, to eliminate the deviation caused by the original unit and absolute value, and to establish a unified, dimensionless data basis for subsequent energy efficiency analysis, correlation calculation and system optimization control.

[0036] The real-time comprehensive load is calculated by the following formula:

[0037] wherein, Indicates real-time aggregate load; Indicates the weighting coefficient. .

[0038] The terminal load index is a quantitative representation of the real-time demand, changing trends, and pressure status of the system's most critical end-user demand units. It reflects the dynamic disturbances and actual demand exerted on the system by the external environment or user behavior. The compressor output index is a precise measure of the compressor's current output capacity, operating efficiency, and health status, representing the system's inherent supply potential and stability boundaries. Weighted fusion of the terminal load index and the compressor output index ensures the system possesses excellent robustness and adaptability when facing the randomness and intermittent fluctuations of the terminal load, as well as changes in compressor output intensity due to equipment aging, fuel variations, or operating condition switching. The system no longer passively and isolatedly responds to changes in a single parameter but can proactively and forward-lookingly adjust its operating status from the perspective of global energy balance, ensuring that total supply and total demand remain precisely matched at all times. The ultimate result is that the system can significantly smooth power fluctuations and suppress oscillation risks under a wide range of operating conditions and uncertain internal and external disturbances, consistently maintaining the operating point within the high-efficiency range. This fundamentally achieves the seemingly contradictory yet crucial comprehensive operating goal of continuous stability and energy efficiency, greatly enhancing the system's intelligence level and overall performance.

[0039] The target speed of the water pump is calculated using the following formula:

[0040] in, Indicates the target speed of the water pump; This indicates the maximum operating speed of the water pump; This indicates the minimum operating speed of the water pump.

[0041] Bivariate weighted fusion improves the sensitivity and stability of control. It enables energy-saving operation under low load and ensures energy supply under high load, thereby improving comfort and efficiency.

[0042] Example 3 This embodiment provides a specific calculation example of a water pump speed control method applied in a heat pump system. Based on Embodiments 1 and 2, this embodiment... The minimum operating speed of the water pump is set to 500 r / min, the maximum operating speed of the water pump is set to 3000 r / min, the system reference rated total power is set to 40 kW, the rated maximum frequency of the compressor is set to 120 Hz, and the weighting coefficient is set to 0.6.

[0043] Measured total power at the terminal = 28 kW; Calculate the end load index = 28 / 40 = 0.7; Measured host frequency = 90 Hz Calculated host output index = 90 / 120 = 0.75; Get real-time comprehensive load = 0.6 x 0.7 + 0.4 x 0.75 = 0.72; Get water pump target rotating speed = 500 + (3000 - 500) x 0.72 ≈ 2280 r / min.

[0044] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, different embodiments or examples described in the present specification and the features of different embodiments or examples can be combined and combined by those skilled in the art without contradiction.

[0045] Obviously, the above embodiments of the present application are only examples for clearly illustrating the present application, and are not intended to limit the embodiments of the present application. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, it is not necessary and impossible to exhaust all the embodiments. Any modification, equivalent replacement and improvement, etc. within the spirit and principles of the present application should be included in the protection scope of the claims of the present application.

Claims

1. A method for controlling the speed of a water pump in a heat pump system, characterized in that, Includes the following steps: Data acquisition: Collect the real-time total power of the terminal and the real-time operating frequency of the compressor, and set the system reference rated total power and the compressor rated maximum frequency; Comprehensive load calculation: Calculate the terminal load index based on the system reference rated total power and the terminal real-time total power; calculate the main unit output index based on the compressor rated maximum frequency and the compressor real-time operating frequency; and calculate the real-time comprehensive load based on the terminal load index and the main unit output index. Target speed calculation: Calculate the target speed of the water pump based on the real-time comprehensive load.

2. The method for controlling the water pump speed in a heat pump system according to claim 1, characterized in that, Specifically, the total power of the acquisition terminal is obtained by acquiring the operating power of each terminal fan coil unit through the bus, and calculating the total terminal power based on the operating power of each terminal fan coil unit.

3. The method for controlling the water pump speed in a heat pump system according to claim 2, characterized in that, The bus uses the 485 bus.

4. The method for controlling the water pump speed in a heat pump system according to claim 2, characterized in that, The total power at the terminal is calculated using the following formula: in, Indicates the total power at the terminal; This indicates the total number of terminal fan coil units; Indicates the first The operating power of each terminal fan coil unit.

5. The method for controlling the water pump speed in a heat pump system according to claim 4, characterized in that, The terminal load index is specifically calculated using the following formula: in, Indicates the end-load index; express Between (0,1); This indicates the system's reference rated total power.

6. The method for controlling the water pump speed in a heat pump system according to claim 5, characterized in that, The host output index is specifically calculated using the following formula: in, Indicates the main unit's output index; This indicates the real-time operating frequency of the compressor; This indicates the compressor's rated maximum frequency.

7. The method for controlling the water pump speed in a heat pump system according to claim 6, characterized in that, The real-time integrated load is calculated by weighting and fusing the terminal load index with the host output index.

8. The method for controlling the water pump speed in a heat pump system according to claim 7, characterized in that, The real-time integrated load is specifically calculated using the following formula: in, Indicates real-time aggregate load; Indicates the weighting coefficient. .

9. The method for controlling the water pump speed in a heat pump system according to claim 8, characterized in that, The target speed of the water pump is calculated using the following formula: in, Indicates the target speed of the water pump; This indicates the maximum operating speed of the water pump; This indicates the minimum operating speed of the water pump.

10. The method for controlling the water pump speed in a heat pump system according to any one of claims 1 to 8, characterized in that, The system's reference rated total power and the compressor's rated maximum frequency can be flexibly configured according to engineering design and usage scenarios.

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