Automatic control method and device for chilled water pump

Abstract

The invention provides an automatic control method and device for a chilled water pump, and the method comprises the steps: detecting the flow direction of liquid in a balance pipe, and if the flow direction is from a water collector to a water segregator, determining that the water demand at the tail end is increased and the flow of the water segregator is insufficient, and increasing the frequency of the chilled water pump until the flow of the liquid in the balance pipe is 0. And when the tail end demand is not changed, the liquid circulation in the chilled water system is kept in a balanced state. When the water quantity demand at the tail end changes, the change of the water quantity demand at the tail end can be judged according to the flow direction of the liquid in the balance pipe. If the liquid flows to the water segregator from the water collector, the frequency of the chilled water pump is increased, so that the liquid flow of the water segregator and the water collector is increased, and the water quantity requirement of the tail end is met. The requirement for the precision of the sensor of the chilled water system is not high, only the balance pipe needs to be arranged between the water segregator and the water collector, and the production cost is reduced. The frequency of the chilled water pump is adjusted according to the flow direction of liquid in the balance pipe, and the response speed is high.

Description

Technical Field

[0001] The present invention relates to the field of chilled water systems, and in particular, to an automatic control method and device for chilled water pumps. Background Art

[0002] At present, the automatic control methods for chilled water pumps in refrigeration machine rooms are mainly divided into differential pressure control and temperature difference control. Differential pressure control controls the chilled water pump according to the differential pressure between the supply and return water pressures in the chilled water system. When the differential pressure is lower than the set value, the frequency of the chilled water pump is increased; when the differential pressure is higher than the set value, the frequency of the chilled water pump is decreased. Temperature difference control controls the chilled water pump according to the temperature difference between the supply and return water temperatures in the chilled water system. When the temperature difference is lower than the set value, the frequency of the chilled water pump is decreased; when the temperature difference is higher than the set value, the frequency of the chilled water pump is increased.

[0003] Differential pressure control responds quickly to pressure, but has high requirements for the accuracy of sensors. Due to the slow change of temperature, the response speed of the temperature difference control system to temperature changes is relatively slow.

[0004] Therefore, an automatic control method for chilled water pumps that has low requirements for the accuracy of system sensors and can achieve a rapid response of the system by detecting water flow changes is needed. Summary of the Invention

[0005] To overcome the problems existing in the related art, the object of the present invention is to provide an automatic control method and device for chilled water pumps, wherein the automatic control method for chilled water pumps has low requirements for the accuracy of system sensors and can achieve a rapid response of the system by detecting water flow changes.

[0006] An automatic control method for chilled water pumps includes:

[0007] Detecting the flow direction of the liquid in the balance pipe;

[0008] If the flow direction is from the water collector to the water distributor, it is determined that the water demand at the end increases and the flow rate of the water distributor is insufficient;

[0009] Increasing the frequency of the chilled water pump until the flow rate of the liquid in the balance pipe is 0.

[0010] In a preferred technical solution of the present invention, after detecting the flow direction of the water flow in the balance pipe, it further includes:

[0011] If the flow direction is from the water distributor to the water collector, it is determined that the water demand at the end decreases and the flow rate of the water distributor is excessive;

[0012] Decreasing the frequency of the chilled water pump until the flow rate of the liquid in the balance pipe is 0.

[0013] In a preferred technical solution of the present invention, increasing the frequency of the chilled water pump includes:

[0014] Detect the flow rate of the liquid in the balance pipe;

[0015] If the flow rate is less than the first flow rate threshold, set the increasing speed of the frequency of the chilled water pump to the first speed;

[0016] If the flow rate is greater than or equal to the first flow rate threshold and less than the second flow rate threshold, set the increasing speed of the frequency of the chilled water pump to the second speed;

[0017] If the flow rate is greater than or equal to the second flow rate threshold, set the increasing speed of the frequency of the chilled water pump to the third speed; wherein, the third speed is greater than the second speed, and the second speed is greater than the first speed.

[0018] In a preferred technical solution of the present invention, reducing the frequency of the chilled water pump includes:

[0019] Detect the flow rate of the liquid in the balance pipe;

[0020] If the flow rate is less than the first flow rate threshold, set the decreasing speed of the frequency of the chilled water pump to the first speed;

[0021] If the flow rate is greater than or equal to the first flow rate threshold and less than the second flow rate threshold, set the decreasing speed of the frequency of the chilled water pump to the second speed;

[0022] If the flow rate is greater than or equal to the second flow rate threshold, set the decreasing speed of the frequency of the chilled water pump to the third speed; wherein, the third speed is greater than the second speed, and the second speed is greater than the first speed.

[0023] In a preferred technical solution of the present invention, the first speed is 0.2Hz / 1s, the second speed is 0.4Hz / 1s, and the third speed is 2Hz / 1s.

[0024] The present invention also provides a chilled water pump automatic control device, which is applied to the chilled water pump automatic control method described in any one of the above. The device includes a balance pipe, and both ends of the balance pipe are respectively connected with a water distributor and a water collector; both ends of the water distributor are respectively connected with a chiller and a terminal; both ends of the water collector are respectively connected with a chilled water pump and the terminal, and the end of the chilled water pump away from the water collector is connected with the chiller.

[0025] In a preferred technical solution of the present invention, a flow meter is arranged in the balance pipe, and the flow meter is used to detect the flow direction and flow rate of the liquid in the balance pipe.

[0026] In a preferred technical solution of the present invention, a secondary pump is further included, and the secondary pump is respectively connected with the water distributor and the terminal.

[0027] In a preferred technical solution of the present invention, the first end of the water separator is connected to the balance pipe, the second end of the water separator is connected to the chiller, and the third end of the water separator is connected to the secondary pump; the liquid flows from the chiller into the water separator and then from the water separator through the secondary pump into the terminal.

[0028] In a preferred technical solution of the present invention, the first end of the water collector is connected to the balance pipe, the second end of the water collector is connected to the chilled water pump, and the third end of the water collector is connected to the terminal; the liquid flows from the terminal into the water collector and then from the water collector through the chilled water pump into the chiller.

[0029] The beneficial effects of the present invention are as follows:

[0030] The present invention provides an automatic control method for a chilled water pump, including detecting the flow direction of the liquid in the balance pipe. When the cooling capacity demand at the terminal increases, the frequency of the secondary pump in the system increases, resulting in a greater water flow demand at the water separator. At this time, the liquid flow direction in the balance pipe is from the water collector to the water separator, so it is necessary to increase the frequency of the chilled water pump. When the demand at the terminal of the chilled water system remains unchanged, the liquid distribution of each component in the chilled water system remains in a balanced state. When the water volume demand at the terminal changes, the liquid in the balance pipe has the characteristic of unidirectional flow. According to the flow direction of the liquid in the balance pipe, the change in the water volume demand at the terminal can be judged. If the liquid flows from the water collector to the water separator, the frequency of the chilled water pump is increased, thereby increasing the liquid flow rate in the water separator and water collector parts to meet the water volume demand at the terminal. In this embodiment, it is only necessary to detect the flow direction of the liquid in the balance pipe, and the accuracy requirement for the sensors of the chilled water system is not high. A balance pipe is arranged between the water separator and the water collector, and no other structures need to be added, which can reduce the production cost. In addition, by adjusting the frequency of the chilled water pump according to the flow direction of the liquid in the balance pipe, the response speed of the chilled water system of the present invention is relatively fast. Description of the Drawings

[0031] Figure 1 is a flowchart for increasing the frequency of the chilled water pump of the present invention;

[0032] Figure 2 is a flowchart for adjusting the increasing speed of the frequency of the chilled water pump of the present invention;

[0033] Figure 3 is a flowchart for decreasing the frequency of the chilled water pump of the present invention;

[0034] Figure 4 is a flowchart for adjusting the decreasing speed of the frequency of the chilled water pump of the present invention;

[0035] Figure 5 is a schematic diagram of the automatic control device for the chilled water pump of the present invention.

[0036] Reference numerals: 1, balance pipe; 2, water distributor; 3, water collector; 4, chiller; 5, terminal; 6, chilled water pump; 7, flowmeter; 8, secondary pump. Detailed implementation manners

[0037] The preferred embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the preferred embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.

[0038] Embodiment 1

[0039] As Figure 1 shown, this embodiment provides an automatic control method for a chilled water pump, including:

[0040] S1: Detect the flow direction of the liquid in the balance pipe;

[0041] S2: If the flow direction is from the water collector to the water distributor, it is determined that the water demand at the terminal increases and the flow rate of the water distributor is insufficient;

[0042] S3: Increase the frequency of the chilled water pump until the flow rate of the liquid in the balance pipe is 0.

[0043] The control system in the refrigeration machine room can detect and control the frequency of the chilled water pump 6. The system controls the frequency of the chilled water pump 6 by detecting the flow direction of the liquid in the balance pipe 1. In this embodiment, the liquid circulating in the whole system is taken as water. The balance pipe 1 is used to detect the flow direction of the liquid in the chilled water system to determine whether the liquid flows from the water collector 3 to the water distributor 2 or from the water distributor 2 to the water collector 3.

[0044] The chiller 4 is the core of the refrigeration component. The function of the chiller 4 is to perform heat and cold exchange and provide a cold source. The chilled water system cools the water entering the chiller 4 and supplies it to users. The chilled water pump 6 provides power for the water circulation of the whole chilled water system. The chilled water system is a closed water system, and the system water volume does not change, but only the water volume distribution in the chilled water system will change.

[0045] The balancing pipe 1 of the present invention only allows liquid to flow unidirectionally, that is, the liquid flows from the water collector 3 to the water distributor 2, or the liquid flows from the water distributor 2 to the water collector 3. When the system detects that the liquid flow direction in the balancing pipe 1 is from the water collector 3 to the water distributor 2, it means that the water demand at the end 5, such as the user end and the equipment end, is increasing. At this time, the flow rate of the water distributor 2 is insufficient, so it is necessary to increase the flow rate of the water distributor 2. The system increases the frequency of the chilled water pump 6 to increase the flow rate of the water distributor 2 to meet the water demand at the end 5.

[0046] In this embodiment, it is only necessary to detect the liquid flow direction in the balancing pipe 1, and the accuracy requirement for the sensors of the chilled water system is not high, and the response speed of the chilled water system is relatively fast. When the chilled water system operates stably, the liquid in the balancing pipe 1 between the water distributor 2 and the water collector 3 does not flow. Therefore, the operating condition of the chilled water system is judged by the liquid flow condition in the balancing pipe 1, and corresponding response actions are taken to adjust the balance of the chilled water system.

[0047] This embodiment provides a method for automatically controlling a chilled water pump 6, including detecting the liquid flow direction in the balancing pipe 1. When the cooling capacity demand at the end 5 increases, the frequency of the secondary pump 8 of the system increases, resulting in a greater water flow demand at the water distributor 2. At this time, the liquid flow direction in the balancing pipe 1 is from the water collector 3 to the water distributor 2, so it is necessary to increase the frequency of the chilled water pump 6. When the demand at the end 5 of the chilled water system remains unchanged, the liquid distribution of each component in the chilled water system remains in a balanced state. When the water demand at the end 5 changes, the liquid in the balancing pipe 1 has the characteristic of unidirectional flow. According to the liquid flow direction in the balancing pipe 1, the change in the water demand at the end 5 can be judged. If the liquid flows from the water collector 3 to the water distributor 2, the frequency of the chilled water pump 6 is increased, thereby increasing the liquid flow rate of the water distributor 2 and the water collector 3 to meet the water demand at the end 5. In this embodiment, it is only necessary to detect the liquid flow direction in the balancing pipe 1, and the accuracy requirement for the sensors of the chilled water system is not high. By setting the balancing pipe 1 between the water distributor 2 and the water collector 3, no other structure needs to be added, which can reduce the production cost. In addition, according to the liquid flow direction in the balancing pipe 1 to adjust the frequency of the chilled water pump 6, the response speed of the chilled water system of the present invention is relatively fast.

[0048] Embodiment 2

[0049] As Figure 1 shown, this embodiment provides a method for automatically controlling a chilled water pump, including:

[0050] S1: Detect the liquid flow direction in the balancing pipe;

[0051] S2: If the flow direction is from the water collector to the water distributor, it is determined that the water demand at the end increases and the flow rate of the water distributor is insufficient;

[0052] S3: Increase the frequency of the chilled water pump until the flow rate of the liquid in the balance pipe is 0.

[0053] As Figure 2 shown, the increasing of the frequency of the chilled water pump includes:

[0054] S31: Detect the flow rate of the liquid in the balance pipe.

[0055] S32: If the flow rate is less than the first flow rate threshold, set the increasing speed of the frequency of the chilled water pump to the first speed.

[0056] S33: If the flow rate is greater than or equal to the first flow rate threshold and less than the second flow rate threshold, set the increasing speed of the frequency of the chilled water pump to the second speed.

[0057] S34: If the flow rate is greater than or equal to the second flow rate threshold, set the increasing speed of the frequency of the chilled water pump to the third speed; where the third speed is greater than the second speed, and the second speed is greater than the first speed.

[0058] The first speed is 0.2Hz / 1s, the second speed is 0.4Hz / 1s, and the third speed is 2Hz / 1s.

[0059] In this embodiment, the liquid for the whole system cycle is taken as water. The chilled water system can not only detect the flow direction of the liquid in the balance pipe 1, but also detect the flow rate of the liquid in the balance pipe 1. The system controls the frequency change of the chilled water pump 6 according to the flow rate of the liquid in the balance pipe 1. The greater the flow rate of the liquid, the faster the frequency change of the chilled water pump 6, and the smaller the flow rate of the liquid, the smaller the frequency change of the chilled water pump 6, so that the system can quickly respond to the water volume demand of the terminal 5 and improve the energy-saving efficiency of the whole chilled water system.

[0060] When the cooling capacity demand of the terminal 5 increases, the chilled water system starts to increase the frequency of the secondary pump 8 to increase the secondary side water flow rate. The secondary side water flow rate refers to the liquid flow rate from the water distributor 2 to the terminal 5 and then from the terminal 5 to the water collector 3. At this time, the chilled water system detects that the flow direction of the liquid in the balance pipe 1 is from the water collector 3 to the water distributor 2, and starts to increase the frequency of the chilled water pump 6 to increase the primary side water flow rate. The primary side water flow rate refers to the liquid flow rate from the water collector 3 to the chiller 4 and then from the chiller 4 to the water distributor 2 to meet the water volume demand of the terminal 5. When the chilled water system detects that the flow rate of the liquid in the balance pipe 1 is 0, that is, the liquid in the balance pipe 1 will not flow from the water collector 3 to the water distributor 2 nor from the water distributor 2 to the water collector 3, it stops increasing the frequency of the chilled water pump 6. At this time, the chilled water system operates stably and the liquid in the balance pipe 1 does not flow.

[0061] Let the first flow rate threshold be v0 , the second flow rate threshold is v 1 , the second flow rate threshold is greater than the first flow rate threshold, the flow rate of the liquid in the balance pipe 1 is v, and the frequency increase rate of the chilled water pump 6 is Δf 1 . When the system detects that the flow direction of the liquid in the balance pipe 1 is from the water collector 3 to the water distributor 2, it is determined that the water demand at the end 5 increases. At this time, the system increases the frequency of the chilled water pump 6 according to the flow rate of the liquid in the balance pipe 1. When the system detects that the flow rate v of the liquid in the balance pipe 1 < v 0 , the system sets the frequency increase rate Δf of the chilled water pump 6 1 to the first speed, and the first speed is 0.2Hz / 1s. When the system detects that the flow rate v of the liquid in the balance pipe 1 0 < v < v 1 , the system sets the frequency increase rate Δf of the chilled water pump 6 1 to the second speed, and the second speed is 0.4Hz / 1s. When the system detects that the flow rate v of the liquid in the balance pipe 1 > v 1 , the system sets the frequency increase rate Δf of the chilled water pump 6 1 to the third speed, and the third speed is 2Hz / 1s. According to the characteristics of the chilled water system, the determination range of the flow rate of the liquid in the balance pipe 1 and the frequency change range of the chilled water system can be increased, so that the liquid flow regulation of the system is more refined and more energy-efficient.

[0062] Increasing the frequency of the chilled water pump 6 in this embodiment includes: detecting the flow rate of the liquid in the balance pipe 1; if the flow rate is less than the first flow rate threshold, setting the increasing speed of the frequency of the chilled water pump 6 to the first speed; if the flow rate is greater than or equal to the first flow rate threshold and less than the second flow rate threshold, setting the increasing speed of the frequency of the chilled water pump 6 to the second speed; if the flow rate is greater than or equal to the second flow rate threshold, setting the increasing speed of the frequency of the chilled water pump 6 to the third speed; where the third speed is greater than the second speed, and the second speed is greater than the first speed. The first speed is 0.2 Hz / 1 s, the second speed is 0.4 Hz / 1 s, and the third speed is 2 Hz / 1 s. Increase the frequency of the chilled water pump 6 until the flow rate of the liquid in the balance pipe 1 is 0. The chilled water system determines the water volume demand at the end 5 based on the flow direction of the liquid in the balance pipe 1. When it is detected that the flow direction of the liquid in the balance pipe 1 is from the water collector 3 to the water distributor 2, it means that the liquid flow rate at the water distributor 2 is insufficient. The system determines that the water volume demand at the end 5 increases and starts to increase the frequency of the chilled water pump 6 to increase the liquid flow rate of the entire chilled water system to meet the water volume demand at the end 5. When the system needs to increase the frequency of the chilled water pump 6, the system increases the frequency of the chilled water pump 6 according to the flow rate of the liquid in the balance pipe 1. The greater the flow rate of the liquid, the greater the increasing speed of the frequency of the chilled water pump 6, and the smaller the flow rate of the liquid, the smaller the increasing speed of the frequency of the chilled water pump 6, so that the system can quickly respond to the water volume demand at the end 5 according to the flow rate of the liquid in the balance pipe 1 and improve the response efficiency of the entire chilled water system.

[0063] Embodiment 3

[0064] As Figure 1 shown, this embodiment provides an automatic control method for a chilled water pump, including

[0065] S1: Detect the flow direction of the liquid in the balance pipe;

[0066] S2: If the flow direction is from the water collector to the water distributor, it is determined that the water volume demand at the end increases and the flow rate at the water distributor is insufficient;

[0067] S3: Increase the frequency of the chilled water pump until the flow rate of the liquid in the balance pipe is 0.

[0068] As Figure 3 shown, after detecting the flow direction of the water flow in the balance pipe, it further includes:

[0069] S21': If the flow direction is from the water distributor to the water collector, it is determined that the water volume demand at the end decreases and the flow rate at the water distributor is excessive;

[0070] S22': Decrease the frequency of the chilled water pump until the flow rate of the liquid in the balance pipe is 0.

[0071] As Figure 4 shown, reducing the frequency of the chilled water pump includes:

[0072] S221’: Detect the flow rate of the liquid in the balance pipe.

[0073] S222’: If the flow rate is less than the first flow rate threshold, set the reduction speed of the frequency of the chilled water pump to the first speed.

[0074] S223’: If the flow rate is greater than or equal to the first flow rate threshold and less than the second flow rate threshold, set the reduction speed of the frequency of the chilled water pump to the second speed.

[0075] S224’: If the flow rate is greater than or equal to the second flow rate threshold, set the reduction speed of the frequency of the chilled water pump to the third speed; where the third speed is greater than the second speed, and the second speed is greater than the first speed.

[0076] The first speed is 0.2Hz / 1s, the second speed is 0.4Hz / 1s, and the third speed is 2Hz / 1s.

[0077] In this embodiment, the liquid for the entire system cycle is taken as water. When the chilled water system detects that the water flow direction in the balance pipe 1 is from the water distributor 2 to the water collector 3, it means that the water flow rate of the water distributor 2 is too large. The excess water in the water distributor 2 directly flows into the water collector 3 through the balance pipe 1. The system determines that the water demand at the end 5 decreases, and then starts to reduce the frequency of the chilled water pump 6 to reduce the primary side water flow rate, so as to reduce the water flow rate from the water collector 3 to the chiller 4 and then from the chiller 4 to the water distributor 2 until the water in the water distributor 2 no longer flows through the balance pipe 1 to the water collector 3, and the water in the water collector 3 also does not flow through the balance pipe 1 to the water distributor 2, that is, when the water in the balance pipe 1 does not flow, the reduction of the frequency of the chilled water pump 6 is stopped. At this time, the chilled water system operates stably and meets the water demand at the end 5.

[0078] Let the first flow rate threshold be v 0 , and the second flow rate threshold be v 1 , the second flow rate threshold is greater than the first flow rate threshold, the flow rate of the liquid in the balance pipe 1 is v, and the reduction speed of the frequency of the chilled water pump 6 is Δf 2 . When the chilled water system needs to reduce the frequency of the chilled water pump 6, the reduction speed of the frequency of the chilled water pump 6 is adjusted by detecting the flow rate of the liquid in the balance pipe 1. When it is detected that the flow rate v of the liquid in the balance pipe 1 is less than the first flow rate threshold v 0 , the system sets the reduction speed of the frequency of the chilled water pump 6 to the first speed, and the first speed is 0.2Hz / 1s. When it is detected that the flow rate v of the liquid in the balance pipe 1 is greater than or equal to the first flow rate threshold v0 and less than the second flow rate threshold value v 1 when the system reduces the frequency reduction speed Δf of the chilled water pump 6 2 to the second speed, and the second speed is 0.4 Hz / 1 s. When it is detected that the flow rate v of the liquid in the balance pipe 1 is greater than or equal to the first flow rate threshold value v 0 and less than the second flow rate threshold value v 1 when the system reduces the frequency reduction speed Δf of the chilled water pump 6 2 to the second speed, and the second speed is 0.4 Hz / 1 s. When it is detected that the flow rate v of the liquid in the balance pipe 1 is greater than or equal to the second flow rate threshold value v 1 the system reduces the frequency reduction speed Δf of the chilled water pump 6 2 to the third speed, and the third speed is 2 Hz / 1 s.

[0079] Reducing the frequency of the chilled water pump 6 in this embodiment includes: detecting the flow rate of the liquid in the balance pipe 1; if the flow rate is less than the first flow rate threshold, setting the frequency reduction speed of the chilled water pump 6 to the first speed; if the flow rate is greater than or equal to the first flow rate threshold and less than the second flow rate threshold, setting the frequency reduction speed of the chilled water pump 6 to the second speed; if the flow rate is greater than or equal to the second flow rate threshold, setting the frequency reduction speed of the chilled water pump 6 to the third speed; where the third speed is greater than the second speed, and the second speed is greater than the first speed. When the system needs to reduce the frequency of the chilled water pump 6, it will adjust the frequency reduction speed of the chilled water pump 6 according to the flow rate of the liquid in the balance pipe 1. The greater the flow rate of the liquid, the greater the frequency reduction speed of the chilled water pump 6, and the smaller the flow rate of the liquid, the smaller the frequency reduction speed of the chilled water pump 6, so that the system can quickly respond to the water volume demand of the terminal 5 according to the flow rate of the liquid in the balance pipe 1 and improve the energy-saving efficiency of the entire chilled water system.

[0080] Embodiment 4

[0081] As Figure 5 shown, this embodiment provides a chilled water pump automatic control device, which is applied to the chilled water pump automatic control method described in any one of the above. The device includes a balance pipe 1, and both ends of the balance pipe 1 are respectively connected with a water distributor 2 and a water collector 3; both ends of the water distributor 2 are respectively connected with a chiller 4 and a terminal 5; both ends of the water collector 3 are respectively connected with a chilled water pump 6 and the terminal 5, and one end of the chilled water pump 6 far from the water collector 3 is connected with the chiller 4.

[0082] A flow meter 7 is arranged in the balance pipe 1, and the flow meter 7 is used to detect the flow direction and flow rate of the liquid in the balance pipe 1.

[0083] The automatic control device of the chilled water pump further includes a secondary pump 8, and the secondary pump 8 is respectively connected to the water distributor 2 and the terminal 5.

[0084] The first end of the water distributor 2 is connected to the balance pipe 1, the second end of the water distributor 2 is connected to the chiller 4, and the third end of the water distributor 2 is connected to the secondary pump 8; the liquid flows from the chiller 4 into the water distributor 2, and then from the water distributor 2 through the secondary pump 8 into the terminal 5.

[0085] The first end of the water collector 3 is connected to the balance pipe 1, the second end of the water collector 3 is connected to the chilled water pump 6, and the third end of the water collector 3 is connected to the terminal 5; the liquid flows from the terminal 5 into the water collector 3, and then from the water collector 3 through the chilled water pump 6 into the chiller 4.

[0086] In this embodiment, the liquid circulating in the whole system is taken as water for example. The chilled water system mainly includes a chiller 4, a water distributor 2, a water collector 3, a chilled water pump 6, a secondary pump 8 and a terminal 5. The chiller 4 is the core of the whole chilled water system, performing heat and cold exchange and being the cold source of the whole chilled water system. The chilled water pump 6 serves as the power for the water circulation, and the secondary pump 8 is for responding faster to the cooling demand of the terminal 5. The balance pipe 1 is arranged between the water distributor 2 and the water collector 3, and both ends of the balance pipe 1 are respectively communicated with the water distributor 2 and the water collector 3. Water can flow from the water distributor 2 to the water collector 3 through the balance pipe 1, or from the water collector 3 to the water distributor 2. When the chilled water system operates stably, the water in the water distributor 2 will not flow through the balance pipe 1 to the water collector 3, and the water in the water collector 3 will not flow through the balance pipe 1 to the water distributor 2 either, that is, the water in the balance pipe 1 will not flow.

[0087] A flowmeter 7 is arranged in the balance pipe 1, which can detect the flow direction and flow rate of the water in the balance pipe 1. Since the installation of the flowmeter 7 affects its measurement accuracy, the design of the balance pipe 1 needs to ensure a horizontal straight pipe section with a diameter 10 times that of the pipe to ensure the measurement accuracy of the flowmeter 7.

[0088] When the cooling demand of the terminal increases, the system will increase the frequency of the secondary pump 8, and more water will flow from the water distributor 2 through the secondary pump 8 to the terminal 5. At this time, the flowmeter 7 will detect that the water in the balance pipe 1 flows from the water collector 3 to the water distributor 2. The system judges that the water volume demand of the terminal 5 increases and the water flow of the water distributor 2 is insufficient. The system increases the frequency of the chilled water pump 6, and more water will flow from the water collector 3 through the chilled water pump 6 to the chiller 4. After the chiller 4 cools the water, the cooled water flows from the chiller 4 to the water distributor 2 to increase the water flow of the water distributor 2 and meet the greater water volume demand of the terminal 5.

[0089] When the end cooling demand decreases, the system reduces the frequency of the secondary pump 8, reducing the flow rate of water from the water distributor 2 through the secondary pump 8 to the end 5. At this time, the flowmeter 7 detects that the water in the balance pipe 1 flows from the water distributor to the water collector 3. The system determines that the water demand at the end 5 has decreased and the water flow rate at the water distributor 2 is too large. The system reduces the frequency of the chilled water pump 6, and the flow rate of water from the water collector 3 through the chilled water pump 6 to the chiller 4 decreases. At the same time, the flow rate of water from the chiller 4 to the water distributor 2 decreases to reduce the water flow rate at the water distributor 2 and meet the smaller water demand at the end 5.

[0090] An automatic control device for a chilled water pump 6 according to this embodiment is applied to an automatic control method for a chilled water pump 6. The device includes a balance pipe 1, and both ends of the balance pipe 1 are respectively connected to a water distributor 2 and a water collector 3; both ends of the water distributor 2 are respectively connected to a chiller 4 and an end 5; both ends of the water collector 3 are respectively connected to a chilled water pump 6 and the end 5, and one end of the chilled water pump 6 away from the water collector 3 is connected to the chiller 4. A flowmeter 7 is arranged in the balance pipe 1, and the flowmeter 7 is used to detect the flow direction and flow rate of the liquid in the balance pipe 1. The automatic control device for the chilled water pump 6 further includes a secondary pump 8, and the secondary pump 8 is respectively connected to the water distributor 2 and the end 5. The first end of the water distributor 2 is connected to the balance pipe 1, the second end of the water distributor 2 is connected to the chiller 4, and the third end of the water distributor 2 is connected to the secondary pump 8; the liquid flows from the chiller 4 into the water distributor 2, and then from the water distributor 2 through the secondary pump 8 into the end 5. The first end of the water collector 3 is connected to the balance pipe 1, the second end of the water collector 3 is connected to the chilled water pump 6, and the third end of the water collector 3 is connected to the end 5; the liquid flows from the end 5 into the water collector 3, and then from the water collector 3 through the chilled water pump 6 into the chiller 4. The chilled water system detects the flow direction and flow rate in the balance pipe 1 through the flowmeter 7 to adjust the frequency of the chilled water pump 6 and meet the water demand at the end 5. When the flowmeter 7 detects that the water flows from the water collector 3 to the water distributor 2, it means that the water supply to the water distributor 2 is insufficient and the water flow demand at the end 5 is large. Therefore, it is necessary to increase the frequency of the chilled water pump 6 to increase the water flow rate on the primary side to meet the demand at the end 5; when it is detected that the water flows from the water distributor 2 to the water collector 3, it means that the water volume at the water distributor 2 is too large and the demand at the end 5 is small, resulting in excess water flowing directly into the water collector 3 through the balance pipe 1. Therefore, it is necessary to reduce the frequency of the chilled water pump 6 to reduce the water flow rate on the primary side and improve the operating efficiency of the system.

[0091] Unless otherwise specifically stated, the relative arrangements of components and steps, numerical expressions, and values set forth in these embodiments do not limit the scope of the present application. In all examples shown and discussed herein, any specific values should be construed as merely exemplary and not as limitations. Thus, other examples of the exemplary embodiments may have different values. It should be noted that like reference numerals and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.

[0092] It should be understood that the spatially relative terms are intended to encompass different orientations in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is inverted, a device described as "above other devices or structures" or "over other devices or structures" will then be oriented "below other devices or structures" or "under other devices or structures". Thus, the exemplary term "above" can include both orientations of "above" and "below". The device may also be oriented in other different ways (rotated 90 degrees or at other orientations), and the spatially relative descriptions used herein should be interpreted accordingly.

[0093] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is merely for the convenience of differentiating the corresponding components. Without otherwise stating, these terms have no special meaning and thus should not be construed as limiting the scope of the present application.

[0094] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for automatically controlling a chilled water pump, characterized in that: include: Detect the flow direction of the liquid in the balance pipe; If the flow direction is from the water collector to the water distributor, it is determined that the water demand at the end increases and the flow rate of the water distributor is insufficient; The frequency of the chilled water pump is increased until the flow rate of the liquid in the balance pipe is zero.

2. The automatic control method for a chilled water pump according to claim 1, characterized in that: After detecting the flow direction of the water flow in the balance pipe, the method further includes: If the flow direction is from the water distributor to the water collector, it is determined that the water demand at the end is reduced and the flow rate of the water distributor is too large; The frequency of the chilled water pump is reduced until the flow rate of the liquid in the balance pipe is zero.

3. The automatic control method for a chilled water pump according to claim 1, characterized in that: The step of increasing the frequency of the chilled water pump comprises: Detecting the flow rate of the liquid in the balance tube; If the flow rate is less than a first flow rate threshold, setting the frequency increase speed of the chilled water pump to a first speed; If the flow rate is greater than or equal to the first flow rate threshold and less than the second flow rate threshold, the frequency increase speed of the chilled water pump is set to the second speed; If the flow rate is greater than or equal to the second flow rate threshold, the frequency increase speed of the chilled water pump is set to a third speed; wherein the third speed is greater than the second speed, and the second speed is greater than the first speed.

4. The automatic control method for a chilled water pump according to claim 2, characterized in that: The reducing the frequency of the chilled water pump comprises: Detecting the flow rate of the liquid in the balance tube; If the flow rate is less than a first flow rate threshold, setting the frequency reduction speed of the chilled water pump to a first speed; If the flow rate is greater than or equal to the first flow rate threshold and less than the second flow rate threshold, the frequency reduction speed of the chilled water pump is set to the second speed; If the flow rate is greater than or equal to the second flow rate threshold, the frequency reduction speed of the chilled water pump is set to a third speed; wherein the third speed is greater than the second speed, and the second speed is greater than the first speed.

5. The automatic control method for a chilled water pump according to claim 3, characterized in that: The first speed is 0.2 Hz / 1 s, the second speed is 0.4 Hz / 1 s, and the third speed is 2 Hz / 1 s.

6. A chilled water pump automatic control device, characterized in that: The automatic control method for a chilled water pump applied to any one of claims 1 to 5, the device comprises a balancing pipe, wherein both ends of the balancing pipe are respectively connected to a water distributor and a water collector; both ends of the water distributor are respectively connected to a chilled water unit and an end; both ends of the water collector are respectively connected to a chilled water pump and the end, and an end of the chilled water pump away from the water collector is connected to the chilled water unit.

7. The automatic control device for a chilled water pump according to claim 6, characterized in that: A flow meter is arranged in the balance pipe, and the flow meter is used to detect the flow direction and flow velocity of the liquid in the balance pipe.

8. The automatic control device for a chilled water pump according to claim 6, characterized in that: It also includes a secondary pump, which is connected to the water distributor and the end respectively.

9. The automatic control device for a chilled water pump according to claim 8, characterized in that: The first end of the water distributor is connected to the balance pipe, the second end of the water distributor is connected to the chiller, and the third end of the water distributor is connected to the secondary pump; the liquid flows from the chiller into the water distributor, and then flows from the water distributor through the secondary pump into the end.

10. The automatic control device for a chilled water pump according to claim 6, characterized in that: The first end of the water collector is connected to the balance pipe, the second end of the water collector is connected to the chilled water pump, and the third end of the water collector is connected to the end; the liquid flows into the water collector from the end, and then flows into the chiller from the water collector through the chilled water pump.

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