Refrigerating machine room energy-saving control system and method based on water pump frequency modulation

Abstract

The invention discloses a refrigerating machine room energy-saving control system and method based on water pump frequency modulation, and particularly relates to the technical field of industrial water pump frequency conversion. The system comprises a cooling tower, a cooling water pump, a refrigerating unit, a chilled water pump, a central air conditioner terminal and an intelligent remote control system; the cooling water pump is connected with the cooling water pipeline; the refrigerating unit is connected with the central air conditioner tail end through a chilled water pipeline, the chilled water pump is connected with the chilled water pipeline, and a cooling water pipeline flowmeter and a chilled water pipeline flowmeter are arranged on the cooling water pipeline and the chilled water pipeline respectively. And the chilled water pipeline flowmeter, the cooling water pipeline flowmeter, the cooling water pump, the chilled water pump and the central air-conditioning terminal are all connected with the intelligent remote control system. The invention can effectively avoid meaningless loss of energy, reduce the power consumption of the water pump, realize a remarkable energy-saving effect and improve the overall operation efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of industrial water pump frequency conversion and the field of central air conditioning energy saving, and in particular to a refrigeration room energy saving control system and method based on water pump frequency modulation. Background Art

[0002] As the world and China attach increasing importance to energy conservation, emission reduction and sustainable development, the problem of building energy consumption has become increasingly prominent. Among them, the central air-conditioning system, as an important part of building energy consumption, accounts for a significant proportion of energy consumption, especially the refrigeration room, as the core part of the central air-conditioning system, its operating efficiency is directly related to the energy consumption level of the entire system. However, traditional refrigeration rooms have many shortcomings in equipment selection, system design and operation control, such as unreasonable equipment selection, poor system matching, low operating efficiency and serious energy waste, which seriously restrict the improvement of the overall energy efficiency of the central air-conditioning system.

[0003] At present, there are still the following deficiencies in the energy-saving optimization of refrigeration rooms in my country:

[0004] (1) The water pump frequency modulation and the central air-conditioning terminal load rate cannot be accurately linked in real time.

[0005] In the refrigeration room, the current situation that the water pump frequency modulation and the central air-conditioning terminal load rate cannot be linked accurately in real time leads to the limitation of energy efficiency optimization. Due to the delay of information transmission between systems, imperfect control strategy or equipment compatibility issues, the water pump frequency modulation often cannot respond quickly to the change of the terminal load rate, thus affecting the operation efficiency and energy saving effect of the whole refrigeration system. For example, China Invention Publication Patent CN117781562A uses a frequency converter to calculate the frequency through sensor data to change the water pump speed. China Invention Publication Patent CN114992783A uses the intelligent linkage between the central air-conditioning terminal and the refrigeration room. However, the above patent scheme does not specifically consider the real-time and accurate linkage between the central air-conditioning terminal load rate and the water pump frequency modulation technology, and cannot make the water pump maintain a low-power and high-efficiency operation state, and cannot achieve high-efficiency energy-saving effect.

[0006] (2) The centrifugal pump is shut down because it cannot completely drain the water due to its special structure.

[0007] When the refrigeration room is shut down, the water pump needs to be shut down for drainage. The existing technology mostly installs a drain valve under the water pump for drainage. Due to the internal structural characteristics of the centrifugal pump, such as the gap between the impeller and the pump casing, the design of the seal and the complexity of the pipe connection, the water cannot be completely drained during the drainage process. The residual water may corrode the equipment and affect the performance and life of the centrifugal pump. For example, China's utility model patent CN219605619U discharges the internal water through the drain port under the centrifugal pump, but does not take into account the special internal structure of the centrifugal pump that may cause residual water. Summary of the invention

[0008] The present invention aims to solve at least one of the above-mentioned technical problems in the prior art to a certain extent. To this end, the present invention provides an energy-saving control system and method for a refrigeration room based on water pump frequency modulation. The real-time and accurate linkage between the water pump frequency modulation and the terminal load rate of the central air-conditioning can ensure that the operating frequency of the water pump is closely matched with the actual load demand of the central air-conditioning, thereby maximizing the utilization of energy.

[0009] In order to achieve the purpose of the present invention, the present invention provides a refrigeration room energy-saving control system based on water pump frequency modulation, including a cooling tower, a cooling water pump, a refrigeration unit, a chilled water pump, a central air-conditioning terminal and an intelligent remote control system.

[0010] The cooling tower is connected to the refrigeration unit through a cooling water pipeline, and the cooling water pump is connected to the cooling water pipeline;

[0011] The refrigeration unit is connected to the terminal of the central air conditioner through a chilled water pipeline, the chilled water pump is connected to the chilled water pipeline, and a cooling water pipeline flow meter and a chilled water pipeline flow meter are respectively provided on the cooling water pipeline and the chilled water pipeline;

[0012] The chilled water pipeline flow meter, cooling water pipeline flow meter, cooling water pump, chilled water pump and central air-conditioning terminal are all connected to the intelligent remote control system. The cooling water pump, chilled water pump and central air-conditioning terminal realize real-time and accurate linkage through the intelligent remote control system. The intelligent remote control system is electrically connected to the cooling water pipeline flow meter, chilled water pipeline flow meter, cooling water pump, chilled water pump and central air-conditioning terminal to achieve control and monitoring.

[0013] Preferably, the cooling water pipeline includes a cooling water supply pipeline and a cooling water outlet pipeline. The cooling tower and the refrigeration unit are connected through the cooling water supply pipeline and the cooling water outlet pipeline to form a loop. The cooling water pump is connected to the cooling water supply pipeline, and the cooling water pipeline flow meter is arranged on the cooling water supply pipeline.

[0014] That is, the cooling tower is connected to the cooling water supply pipeline; the cooling tower is connected to the cooling water outlet pipeline; the central air-conditioning terminal is connected to the chilled water supply pipeline; the central air-conditioning terminal is connected to the chilled water outlet pipeline; the refrigeration unit is connected to the cooling water supply pipeline; the refrigeration unit is connected to the cooling water outlet pipeline; the refrigeration unit is connected to the chilled water supply pipeline; the refrigeration unit is connected to the chilled water outlet pipeline.

[0015] Preferably, a cooling water gas pump is also provided, and the cooling water gas pump is connected to the water inlet of the cooling water pump through a pipeline. The cooling water gas pump is connected to the water inlet of the cooling water pump through a hose. When the centrifuge is stopped, the gas pump is introduced with compressed air, and the residual liquid in the pump is effectively discharged by using the air pressure difference, thereby improving the overall operating efficiency and achieving energy saving effect.

[0016] The cooling water pump is connected to the cooling water supply pipeline.

[0017] Preferably, the pipeline is a hose.

[0018] Preferably, the chilled water pipeline includes a chilled water supply pipeline and a chilled water outlet pipeline. The refrigeration unit and the central air-conditioning terminal are connected through the chilled water supply pipeline and the chilled water outlet pipeline to form a loop. The chilled water pump is connected to the chilled water supply pipeline, and the chilled water pipeline flow meter is arranged on the chilled water supply pipeline.

[0019] Preferably, a chilled water gas pump is also provided, and the chilled water gas pump is connected to the water inlet of the chilled water pump through a pipeline. The chilled water gas pump is connected to the water inlet of the chilled water pump through a hose. When the centrifuge is stopped, the gas pump is introduced with compressed air, and the residual liquid in the pump is discharged promptly and effectively by using the air pressure difference, thereby improving the overall operating efficiency and achieving energy saving effect.

[0020] The chilled water pump is connected to the chilled water supply pipeline.

[0021] The present invention also provides a refrigeration room energy-saving control method based on water pump frequency modulation, which is implemented based on the above system and includes the following steps:

[0022] Step S1, the intelligent remote control system monitors the load rate of the central air-conditioning terminal;

[0023] Step S2, the intelligent remote control system calculates the required flow of cooling water and chilled water according to the load rate, and outputs a cooling water and chilled water flow demand signal F1 to transmit to the cooling water pump and the chilled water pump;

[0024] Step S3, the cooling water pump and the chilled water pump are frequency-modulated according to the flow demand to reach the required speed n;

[0025] Step S4, the intelligent remote control system monitors the flow on the corresponding pipelines through the cooling water pipeline flow meter and the chilled water pipeline flow meter;

[0026] Step S5, if the flow rate after frequency modulation meets the cooling demand, the terminal demand is met; otherwise, step S3 is repeated to perform frequency modulation until the flow demand is met to achieve energy-saving effect.

[0027] Preferably, in step S3, the cooling water pump and the chilled water pump are matched to the pump frequencies of the cooling water pump and the chilled water pump in the pump characteristic curves of the cooling water pump and the chilled water pump respectively in combination with the required flow rates of the cooling water and the chilled water in step S2, and the speed of the corresponding pump is adjusted based on the pump frequency.

[0028] Preferably, when matching the water pump frequency, the difference ΔF is obtained by subtracting the cooling water and chilled water flow demand signal F1 from the existing cooling water and chilled water flow signal F2. Based on the cooling water and chilled water flow demand signal F1 and the difference ΔF, and combined with the relationship curve between the efficiency, shaft power and flow in the water pump characteristic curve, a low-power and high-efficiency point is matched. The water pump frequency corresponding to the low-power and high-efficiency point is the required water pump frequency f.

[0029] Preferably, in steps S4-S5, the flow rate obtained after frequency modulation is monitored by a cooling water pipeline flow meter and a chilled water pipeline flow meter to determine whether the flow rate after frequency modulation is equal to the cooling water and chilled water flow demand signal F1. If not, the water pump characteristic curve is re-matched to a low power and high efficiency point to reach the cooling water and chilled water flow demand signal F1, thereby satisfying the refrigeration demand of the central air-conditioning terminal and achieving the refrigeration demand; otherwise, the process ends.

[0030] Compared with the prior art, the beneficial effects of the present invention include:

[0031] (1) The present invention discloses an energy-saving control system and method for a refrigeration room based on water pump frequency modulation. The method can calculate the required flow rate of cooling water and chilled water through an intelligent remote control system according to the change of the terminal load rate. The required water pump frequency is then obtained through the water pump characteristic curve and flow calculation matching. The water pump speed is adjusted through a frequency converter. While meeting the flow demand, the water pump energy consumption is reduced, the economic benefit is improved, and the energy-saving effect is achieved.

[0032] (2) The real-time and precise linkage between the water pump frequency modulation and the terminal load rate of the central air conditioner can ensure that the operating frequency of the water pump is closely matched with the actual load demand of the central air conditioner, thereby maximizing the utilization of energy. Specifically, when the terminal load rate of the central air conditioner increases, the water pump frequency modulation system can automatically increase the operating frequency of the water pump to meet the increased cooling demand; conversely, when the load rate decreases, the operating frequency of the water pump will also be reduced accordingly to avoid unnecessary energy waste. This real-time linkage method not only improves the response speed and adjustment accuracy of the system, but also significantly reduces energy consumption, extends the service life of the equipment, and provides a more comfortable and energy-saving indoor environment for the building. At the same time, this also reflects the development trend of intelligent and green modern buildings, which is of great significance for promoting energy conservation and emission reduction and achieving sustainable development.

[0033] (3) The benefit of using an air pump to drain the residual liquid from a centrifugal pump lies in its high efficiency and significant effect on equipment protection. The air pump can effectively drain the residual liquid in the pump by introducing compressed air into the centrifugal pump and using the air pressure difference. This method can quickly and relatively thoroughly remove the residual water in the pump body, avoiding rust and corrosion problems caused by long-term water accumulation, thereby protecting the internal structure and key components of the centrifugal pump and extending the service life of the equipment. In addition, using an air pump to drain water also reduces the tedious work and possible mechanical damage caused by disassembling the pump body for drainage, thereby improving maintenance efficiency and safety. Therefore, using an air pump to drain the residual liquid from a centrifugal pump is an economical and practical maintenance method. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a structural schematic diagram of a refrigeration room energy-saving control system based on water pump frequency modulation according to an embodiment of the present invention;

[0035] Figure 2 This is a diagram of the water pump frequency modulation steps in this embodiment of the present invention;

[0036] Figure 3 This is a schematic diagram of the frequency modulation principle of the water pump in this embodiment of the present invention;

[0037] In the figure: 1. Cooling tower; 2. Cooling water pump; 3. Cooling water supply pipeline; 4. Refrigeration unit; 5. Chilled water supply pipeline; 6. Chilled water pump; 7. Central air conditioning terminal; 8. Chilled water outlet pipeline; 9. Chilled water pipeline flow meter; 10. Cooling water pipeline flow meter; 11. Cooling water outlet pipeline; 12. Intelligent remote control system; 21. Cooling water gas pump; 22. Chilled water gas pump. DETAILED DESCRIPTION

[0038] This section will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but it cannot be understood as a limitation on the scope of protection of the present invention.

[0039] like Figure 1As shown, the present invention provides a refrigeration room energy-saving control system based on water pump frequency modulation, including a cooling tower 1, a cooling water pump 2, a cooling water supply pipeline 3, a refrigeration unit 4, a chilled water supply pipeline 5, a chilled water pump 6, a central air-conditioning terminal 7, a chilled water outlet pipeline 8, a chilled water pipeline flow meter 9, a cooling water pipeline flow meter 10, a cooling water outlet pipeline 11, an intelligent remote control system 12, a cooling water gas pump 21 and a chilled water gas pump 22. The cooling tower 1 is connected to the cooling water supply pipeline 3 and the cooling water outlet pipeline 11 to provide cooling water and cool the cooling water; the chilled water supply pipeline 5 and the chilled water outlet pipeline 8 are both connected to the central air-conditioning terminal 7 to transport chilled water to provide cooling capacity for the central air-conditioning terminal 7.

[0040] The cooling water pump 2 is connected to the cooling water supply pipeline 3, and the chilled water pump 6 is connected to the chilled water supply pipeline 5. The water pump frequency conversion is used to change the rotation speed, thereby changing the water delivery volume to meet the terminal requirements and achieve energy-saving effects.

[0041] The refrigeration unit 4 is connected to the cooling water supply pipeline 3, the cooling water outlet pipeline 11, the chilled water supply pipeline 5, and the chilled water outlet pipeline 8. The refrigerant is used in the refrigeration unit 4 to indirectly exchange heat between the cooling water and the chilled water, so that the chilled water is reduced to the set temperature to meet the cooling demand.

[0042] The cooling water pipeline flow meter 10 is installed on the cooling water supply pipeline 3, and the chilled water pipeline flow meter 9 is installed on the chilled water supply pipeline 5, and the cooling water pipeline flow meter 10 and the chilled water pipeline flow meter 9 are both electrically connected to the intelligent remote control system 12 to monitor the flow of cooling water and chilled water; at the same time, after the water pump frequency is modulated, it is monitored whether the cooling water and chilled water flows meet the set values, thereby providing feedback regulation.

[0043] In some embodiments of the present invention, the cooling water gas pump 21 is connected to the water inlet of the cooling water pump 2 through a hose; the chilled water gas pump 22 is connected to the water inlet of the chilled water pump 6 through a hose. When the refrigeration room is shut down, compressed air is introduced into the cooling water gas pump 21 and the chilled water gas pump 22, and the residual liquid in the cooling water pump 2 and the chilled water pump 6 is effectively discharged by utilizing the air pressure difference, thereby avoiding rust and corrosion problems caused by long-term water accumulation, thereby protecting the internal structure and key components of the centrifugal pump, extending its life, improving the operation efficiency of the water pump, and achieving energy-saving effects.

[0044] The present invention provides a refrigeration room energy-saving control method based on water pump frequency modulation, which specifically includes the following steps:

[0045] Step S1, the intelligent remote control system 12 monitors the load rate of the central air-conditioning terminal 7;

[0046] Step S2, the intelligent remote control system 12 calculates the required flow of cooling water and chilled water according to the load rate, and transmits the cooling water and chilled water flow demand signal F1 to the cooling water pump 2 and the chilled water pump 6, wherein the cooling water and chilled water flow demand signal F1 includes a cooling water flow demand signal and a chilled water flow demand signal;

[0047] Step S3, the cooling water pump 2 and the chilled water pump 6 are frequency-modulated according to the corresponding flow demand signal to reach the required pump speed n;

[0048] Step S4, the intelligent remote control system 12 monitors the flow on the corresponding pipelines through the cooling water pipeline flow meter 10 and the chilled water pipeline flow meter 9;

[0049] Step S5, if the flow rate after frequency modulation meets the cooling demand, the terminal demand is met; otherwise, repeat step S3 to perform frequency modulation until the flow demand is met.

[0050] Terminal demand: The appropriate cooling capacity corresponding to the terminal load rate of the central air conditioner to avoid excessive cooling capacity and excessive energy loss.

[0051] Flow demand: The chilled water flow rate corresponding to the cooling capacity required by the central air-conditioning terminal. When the refrigeration unit is exchanging heat, the chilled water flow rate determines the cooling water flow rate. Therefore, the water pump frequency is modulated to control the flow rate to meet the flow demand.

[0052] In some embodiments of the present invention, step S3 includes: the cooling water pump 2 and the chilled water pump 6 obtain the required pump frequency f by matching the pump characteristic curves of the cooling water pump and the chilled water pump, combined with the required flow rates of cooling water and chilled water calculated in step S2; and adjust the pump speed n through the frequency converter to meet the cooling water and chilled water flow requirements.

[0053] Specifically, step S3 includes: the intelligent remote control system 12 calculates and outputs the cooling water and chilled water flow demand signal F1 according to the refrigeration capacity demand of the central air-conditioning terminal, and subtracts it from the existing cooling water and chilled water flow signal F2 (the existing cooling water and chilled water flow signal F2 is obtained by uploading the monitoring results of the flow meters on the corresponding cooling water and chilled water pipelines to the intelligent remote control system) to obtain a difference ΔF, and uses the pump characteristic curves of the cooling water pump 2 and the chilled water pump 6, the pump characteristic curves including the relationship curves of the head H and the flow F, the efficiency η and the flow F, and the shaft power P and the flow F. Combined with the flow demand, the low power and high efficiency point is calculated and matched (at this point, both low power and high efficiency effects are achieved), and then the required pump frequency f is matched; the pump speed n is adjusted through the frequency converter.

[0054] The pump characteristic curve includes the relationship curves of head H and flow F, efficiency η and flow F, shaft power P and flow F, etc. According to the flow signal F1 and ΔF outputted by the central air conditioner terminal (ΔF is used to represent a process of flow adjustment from F1 to F2, that is, there is a difference signal between F1 and F2, and it is adjusted to the corresponding F1 by matching the characteristic curve), according to the relationship curve of efficiency, shaft power and flow, the low power and high efficiency point with the best effect of the two is obtained, and the pump frequency corresponding to this point is the required pump frequency f. It satisfies the energy-saving and high-efficiency benefits of the entire control system.

[0055] In some embodiments of the present invention, in steps S4-S5, the flow meter is used for monitoring to determine whether the frequency-modulated flow rate F meets the cooling water and chilled water flow demand signal F1. If they are not equal, the low-power and high-efficiency point is re-matched through the water pump characteristic curve to achieve the cooling water and chilled water flow demand signal F1, meet the cooling demand of the central air-conditioning terminal 7, and achieve the cooling demand; otherwise, the process ends.

[0056] The system and method provided by the aforementioned embodiments of the present invention associate a variable frequency water pump, an intelligent remote control system, and a central air-conditioning terminal load rate. The required flow rate can be obtained through the intelligent remote control system according to actual needs, thereby adjusting the rotation speed of the water pump so that the operating characteristic curve of the water pump matches the flow demand in the system, thereby effectively avoiding unnecessary energy loss. The voltage is also adjusted while the frequency is changed, thereby reducing the power consumption of the water pump. At the same time, when the water pump is shut down, an air pump can be used to empty the residual water in the centrifugal pump, thereby avoiding rust, corrosion and microbial growth caused by the residual water, affecting the performance and life of the centrifugal pump, achieving significant energy-saving effects, and improving the overall operating efficiency. It is committed to the comprehensive optimization of the central air-conditioning refrigeration room, and aims to reduce building energy consumption and improve system energy efficiency by optimizing key links such as water pumps.

[0057] The embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the knowledge scope of ordinary technicians in the technical field without departing from the purpose of the present invention.

Claims

1. A refrigeration room energy-saving control system based on water pump frequency modulation, characterized in that: It comprises a cooling tower (1), a cooling water pump (2), a refrigeration unit (4), a chilled water pump (6), a central air conditioning terminal (7) and an intelligent remote control system (12). The cooling tower (1) is connected to the refrigeration unit (4) via a cooling water pipeline, and the cooling water pump (2) is connected to the cooling water pipeline; The refrigeration unit (4) is connected to the central air conditioning terminal (7) via a chilled water pipeline, the chilled water pump (6) is connected to the chilled water pipeline, and a cooling water pipeline flow meter (10) and a chilled water pipeline flow meter (9) are respectively provided on the cooling water pipeline and the chilled water pipeline; The chilled water pipeline flow meter (9), the cooling water pipeline flow meter (10), the cooling water pump (2), the chilled water pump (6) and the central air conditioning terminal (7) are all connected to the intelligent remote control system (12).

2. According to claim 1, a refrigeration room energy-saving control system based on water pump frequency modulation is characterized in that: The cooling water pipeline comprises a cooling water supply pipeline (3) and a cooling water outlet pipeline (11); the cooling tower (1) and the refrigeration unit (4) are connected via the cooling water supply pipeline (3) and the cooling water outlet pipeline (11) to form a loop; the cooling water pump (2) is connected to the cooling water supply pipeline (3); and a cooling water pipeline flow meter (10) is arranged on the cooling water supply pipeline (3).

3. The energy-saving control system for a refrigeration room based on water pump frequency modulation according to claim 2 is characterized in that: A cooling water gas pump (21) is also provided, and the cooling water gas pump (21) is connected to the water inlet of the cooling water pump (2) through a pipeline.

4. The energy-saving control system for a refrigeration room based on water pump frequency modulation according to claim 3 is characterized in that: The pipeline is a hose.

5. The energy-saving control system for a refrigeration room based on water pump frequency modulation according to claim 1 is characterized in that: The chilled water pipeline comprises a chilled water supply pipeline (5) and a chilled water outlet pipeline (8); the refrigeration unit (4) and the central air-conditioning terminal (7) are connected via the chilled water supply pipeline (5) and the chilled water outlet pipeline (8) to form a loop; the chilled water pump (6) is connected to the chilled water supply pipeline (5), and a chilled water pipeline flow meter (9) is arranged on the chilled water supply pipeline (5).

6. A refrigeration room energy-saving control system based on water pump frequency modulation according to any one of claims 1 to 5, characterized in that: A chilled water gas pump (22) is also provided, and the chilled water gas pump (22) is connected to the water inlet of the chilled water pump (6) via a pipeline.

7. A refrigeration room energy-saving control method based on water pump frequency modulation, characterized in that: Based on the system implementation according to any one of claims 1 to 6, the method comprises the following steps: Step S1, the intelligent remote control system (12) monitors the load rate of the central air-conditioning terminal (7); Step S2, the intelligent remote control system (12) calculates the required flow rates of cooling water and chilled water according to the load rate, and outputs a cooling water and chilled water flow demand signal F1 to transmit to the cooling water pump (2) and the chilled water pump (6); Step S3, the cooling water pump (2) and the chilled water pump (6) are frequency-modulated according to flow requirements to reach a required rotation speed n; Step S4, the intelligent remote control system (12) monitors the flow rates on the corresponding pipelines through the cooling water pipeline flow meter (10) and the chilled water pipeline flow meter (9); Step S5, if the flow rate after frequency modulation meets the cooling demand, the terminal demand is met; otherwise, step S3 is repeated to perform frequency modulation until the flow demand is met to achieve energy-saving effect.

8. The energy-saving control method for a refrigeration room based on water pump frequency modulation according to claim 7 is characterized in that: In step S3, the cooling water pump (2) and the chilled water pump (6) are matched to the pump frequencies of the cooling water pump (2) and the chilled water pump (6) in the pump characteristic curves of the cooling water pump and the chilled water pump respectively in combination with the required flow rates of the cooling water and the chilled water in step S2, and the rotation speeds of the corresponding pumps are adjusted based on the pump frequencies.

9. The energy-saving control method for a refrigeration room based on water pump frequency modulation according to claim 8 is characterized in that: When matching the water pump frequency, the difference ΔF is obtained by subtracting the cooling water and chilled water flow demand signal F1 from the existing cooling water and chilled water flow signal F2. According to the cooling water and chilled water flow demand signal F1 and the difference ΔF, and combined with the relationship curve between the efficiency, shaft power and flow in the water pump characteristic curve, a low-power and high-efficiency point is matched. The water pump frequency corresponding to the low-power and high-efficiency point is the required water pump frequency f.

10. The energy-saving control method for a refrigeration room based on water pump frequency modulation according to claim 8, characterized in that: In step S4-S5, the flow rate obtained after frequency modulation is monitored by the cooling water pipeline flow meter (10) and the chilled water pipeline flow meter (9), and it is determined whether the flow rate after frequency modulation is equal to the cooling water and chilled water flow demand signal F1. If not, the water pump characteristic curve is re-matched to a low power and high efficiency point to reach the cooling water and chilled water flow demand signal F1, thereby satisfying the cooling demand of the central air-conditioning terminal (7) and achieving the cooling demand; otherwise, the process ends.

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