CN112432326A

CN112432326A - Control method and device of refrigeration secondary pump, air conditioning system, medium and processor

Info

Publication number: CN112432326A
Application number: CN202011305294.0A
Authority: CN
Inventors: 王升; 刘昊; 吴宁波; 宋炎林; 刘国林
Original assignee: Gree Electric Appliances Inc of Zhuhai
Current assignee: Gree Electric Appliances Inc of Zhuhai
Priority date: 2020-11-19
Filing date: 2020-11-19
Publication date: 2021-03-02
Anticipated expiration: 2040-11-19
Also published as: CN112432326B

Abstract

The invention discloses a control method and a control device for a refrigeration secondary pump, an air conditioning system, a storage medium and a processor, wherein the method comprises the following steps: collecting a variable frequency control input signal of a refrigerating secondary pump, and acquiring the frequency and the lift of the refrigerating secondary pump; determining the target frequency of the freezing secondary pump according to the variable frequency control input signal of the freezing secondary pump; determining a machine subtracting parameter of the freezing secondary pump or a machine adding parameter of the freezing secondary pump according to the frequency of the freezing secondary pump and the lift of the freezing secondary pump; controlling the refrigerating secondary pump to operate in a machine reducing mode according to the target frequency of the refrigerating secondary pump and the machine reducing parameters of the refrigerating secondary pump; or controlling the machine adding operation of the freezing secondary pump according to the target frequency of the freezing secondary pump and the machine adding parameters of the freezing secondary pump. This scheme is through on the basis of guaranteeing the reliable operation of freezing second grade pump, further improves the operating efficiency of freezing second grade pump to promote energy-conserving effect.

Description

Control method and device of refrigeration secondary pump, air conditioning system, medium and processor

Technical Field

The invention belongs to the technical field of air conditioning systems, and particularly relates to a control method and device of a refrigeration secondary pump, an air conditioning system, a storage medium and a processor, and particularly relates to a frequency conversion control method and device of the refrigeration secondary pump, the air conditioning system, the storage medium and the processor.

Background

The design scheme of a primary pump and a secondary pump is generally adopted in a large commercial centralized air-conditioning system so as to adapt to different requirements of air-conditioning water systems in different air-conditioning building areas on a refrigeration water supply pressure head. In the related scheme, the refrigeration secondary pump generally adopts a method of controlling the number of the refrigeration secondary pumps and adjusting the main pipe bypass valve, so that the variable flow rate adjustment requirement of the tail end air-conditioning water system on the chilled water is adjusted, and the energy-saving effect is poor.

The above is only for the purpose of assisting understanding of the technical aspects of the present invention, and does not represent an admission that the above is prior art.

Disclosure of Invention

The invention aims to provide a control method and device of a refrigerating secondary pump, an air conditioning system, a storage medium and a processor, which aim to solve the problem of poor energy-saving effect caused by the fact that the refrigerating secondary pump adopts a mode of controlling the number of refrigerating secondary pumps and adjusting a main pipe bypass valve to adjust the variable flow rate of chilled water required by a tail end air conditioning water system, and achieve the effect of improving the energy-saving effect by further improving the operation efficiency of the refrigerating secondary pump on the basis of ensuring the reliable operation of the refrigerating secondary pump.

The invention provides a control method of a refrigeration two-stage pump, which comprises the following steps: collecting a variable frequency control input signal of the refrigeration secondary pump, and acquiring the frequency and the lift of the refrigeration secondary pump; determining a target frequency of the freezing secondary pump according to a variable frequency control input signal of the freezing secondary pump; determining a machine subtracting parameter of the freezing secondary pump or a machine adding parameter of the freezing secondary pump according to the frequency of the freezing secondary pump and the lift of the freezing secondary pump; controlling the refrigerating secondary pump to operate in a machine reducing mode according to the target frequency of the refrigerating secondary pump and the machine reducing parameter of the refrigerating secondary pump; or controlling the machine adding operation of the freezing secondary pump according to the target frequency of the freezing secondary pump and the machine adding parameters of the freezing secondary pump.

In some embodiments, determining a target frequency of the cryogenic secondary pump based on a variable frequency control input signal of the cryogenic secondary pump comprises: calculating the target frequency of the freezing secondary pump by adopting a freezing secondary pump variable frequency control algorithm according to the variable frequency control input signal of the freezing secondary pump; the frequency conversion control algorithm of the refrigeration secondary pump comprises the following steps: and a PID control algorithm of the freezing secondary pump frequency.

In some embodiments, the subtracting parameter comprises: the maximum machine reducing frequency of the freezing secondary pump and the target frequency of the freezing secondary pump after machine reduction; determining a machine reduction parameter of the freezing secondary pump according to the frequency of the freezing secondary pump and the lift of the freezing secondary pump, wherein the machine reduction parameter comprises the following steps: under the condition that the refrigerating secondary pump needs to be reduced, determining the flow of the refrigerating secondary pump by adopting a corresponding relation among set flow, set lift and set frequency; determining the maximum machine reducing frequency of the freezing secondary pump according to the flow of the freezing secondary pump; and determining the target frequency of the refrigerating secondary pump after the machine reduction according to the flow curve of the refrigerating secondary pump.

In some embodiments, controlling the cryosecondary pump derate operation as a function of the target frequency of the cryosecondary pump and the derate parameter of the cryosecondary pump comprises: after the target frequency of the freezing secondary pump after the machine reduction is determined, changing the running frequency of an online freezing secondary pump in the freezing secondary pump into the target frequency of the freezing secondary pump after the machine reduction; and, determining whether the target frequency of the cryogenic secondary pump is less than a maximum derating frequency of the cryogenic secondary pump; if the target frequency of the freezing secondary pump is less than the maximum machine reducing frequency of the freezing secondary pump, closing an online freezing secondary pump with the longest operation time, and changing the operation frequency of the online freezing secondary pump in the freezing secondary pump into the target frequency after the machine reduction of the freezing secondary pump; and if the target frequency of the secondary freezing pump is greater than or equal to the maximum machine reducing frequency of the secondary freezing pump, controlling the secondary freezing pump to change the operating frequency.

In some embodiments, the machining parameters include: the minimum machining frequency of the freezing secondary pump and the target frequency of the freezing secondary pump after machining; determining the machining parameters of the freezing secondary pump according to the frequency of the freezing secondary pump and the lift of the freezing secondary pump, wherein the machining parameters comprise: under the condition that the refrigerating secondary pump needs to be added, determining the flow of the refrigerating secondary pump by adopting a corresponding relation among set flow, set lift and set frequency according to the frequency of the refrigerating secondary pump and the lift of the refrigerating secondary pump; determining the minimum adding frequency of the freezing secondary pump according to the flow of the freezing secondary pump; and determining the target frequency of the refrigerating secondary pump after the machine is added according to the flow curve of the refrigerating secondary pump.

In some embodiments, controlling the cryogenic secondary pump machine operation based on the target frequency of the cryogenic secondary pump and the machine parameters of the cryogenic secondary pump comprises: determining whether a target frequency of the cryogenic secondary pump is greater than a minimum pump-up frequency of the cryogenic secondary pump; if the target frequency of the freezing secondary pump is greater than the minimum adding frequency of the freezing secondary pump, starting an offline freezing secondary pump with the shortest calendar history running time, and changing the running frequency of the online freezing secondary pump in the freezing secondary pump into the target frequency of the freezing secondary pump after adding the machine; and if the target frequency of the freezing secondary pump is less than or equal to the minimum machining frequency of the freezing secondary pump, controlling the freezing secondary pump to change the operating frequency.

In accordance with another aspect of the present invention, there is provided a control apparatus for a refrigeration secondary pump, including: the detection unit is configured to collect a variable frequency control input signal of the refrigeration secondary pump and acquire the frequency and the lift of the refrigeration secondary pump; a determination unit configured to determine a target frequency of the cryogenic secondary pump from a variable frequency control input signal of the cryogenic secondary pump; determining a machine subtracting parameter of the freezing secondary pump or a machine adding parameter of the freezing secondary pump according to the frequency of the freezing secondary pump and the lift of the freezing secondary pump; a control unit configured to control the freezing secondary pump to run in a reduced mode according to a target frequency of the freezing secondary pump and a reduced mode parameter of the freezing secondary pump; or controlling the machine adding operation of the freezing secondary pump according to the target frequency of the freezing secondary pump and the machine adding parameters of the freezing secondary pump.

In some embodiments, the determining unit, based on the variable frequency control input signal of the cryogenic secondary pump, determines the target frequency of the cryogenic secondary pump, comprising: calculating the target frequency of the freezing secondary pump by adopting a freezing secondary pump variable frequency control algorithm according to the variable frequency control input signal of the freezing secondary pump; the frequency conversion control algorithm of the refrigeration secondary pump comprises the following steps: and a PID control algorithm of the freezing secondary pump frequency.

In some embodiments, the subtracting parameter comprises: the maximum machine reducing frequency of the freezing secondary pump and the target frequency of the freezing secondary pump after machine reduction; the determining unit determines a machine reduction parameter of the freezing secondary pump according to the frequency of the freezing secondary pump and the head of the freezing secondary pump, and comprises the following steps: under the condition that the refrigerating secondary pump needs to be reduced, determining the flow of the refrigerating secondary pump by adopting a corresponding relation among set flow, set lift and set frequency; determining the maximum machine reducing frequency of the freezing secondary pump according to the flow of the freezing secondary pump; and determining the target frequency of the refrigerating secondary pump after the machine reduction according to the flow curve of the refrigerating secondary pump.

In some embodiments, the control unit, controlling the cryosecondary pump derate operation according to a target frequency of the cryosecondary pump and a derate parameter of the cryosecondary pump, comprises: after the target frequency of the freezing secondary pump after the machine reduction is determined, changing the running frequency of an online freezing secondary pump in the freezing secondary pump into the target frequency of the freezing secondary pump after the machine reduction; and, determining whether the target frequency of the cryogenic secondary pump is less than a maximum derating frequency of the cryogenic secondary pump; if the target frequency of the freezing secondary pump is less than the maximum machine reducing frequency of the freezing secondary pump, closing an online freezing secondary pump with the longest operation time, and changing the operation frequency of the online freezing secondary pump in the freezing secondary pump into the target frequency after the machine reduction of the freezing secondary pump; and if the target frequency of the secondary freezing pump is greater than or equal to the maximum machine reducing frequency of the secondary freezing pump, controlling the secondary freezing pump to change the operating frequency.

In some embodiments, the machining parameters include: the minimum machining frequency of the freezing secondary pump and the target frequency of the freezing secondary pump after machining; the determining unit determines the machining parameters of the freezing secondary pump according to the frequency of the freezing secondary pump and the head of the freezing secondary pump, and comprises the following steps: under the condition that the refrigerating secondary pump needs to be added, determining the flow of the refrigerating secondary pump by adopting a corresponding relation among set flow, set lift and set frequency according to the frequency of the refrigerating secondary pump and the lift of the refrigerating secondary pump; determining the minimum adding frequency of the freezing secondary pump according to the flow of the freezing secondary pump; and determining the target frequency of the refrigerating secondary pump after the machine is added according to the flow curve of the refrigerating secondary pump.

In some embodiments, the control unit, controlling the refrigeration secondary pump to operate according to a target frequency of the refrigeration secondary pump and a machine parameter of the refrigeration secondary pump, includes: determining whether a target frequency of the cryogenic secondary pump is greater than a minimum pump-up frequency of the cryogenic secondary pump; if the target frequency of the freezing secondary pump is greater than the minimum adding frequency of the freezing secondary pump, starting an offline freezing secondary pump with the shortest calendar history running time, and changing the running frequency of the online freezing secondary pump in the freezing secondary pump into the target frequency of the freezing secondary pump after adding the machine; and if the target frequency of the freezing secondary pump is less than or equal to the minimum machining frequency of the freezing secondary pump, controlling the freezing secondary pump to change the operating frequency.

In accordance with another aspect of the present invention, there is provided an air conditioning system including: the control device of the refrigerating two-stage pump.

In accordance with the above method, a further aspect of the present invention provides a storage medium including a stored program, wherein the program, when executed, controls an apparatus in which the storage medium is located to perform the above control method for a secondary refrigeration pump.

In keeping with the above method, a further aspect of the invention provides a processor for executing a program, wherein the program is executed to perform the above method for controlling a cryogenic secondary pump.

Therefore, according to the scheme of the invention, the frequency of the water pump adding and subtracting is determined through the built-in water pump model, and the operation efficiency of the refrigeration secondary pump is further improved on the basis of ensuring the reliable operation of the refrigeration secondary pump, so that the energy-saving effect is improved.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

The technical solution of the present invention is further described in detail by the accompanying drawings and embodiments.

Drawings

FIG. 1 is a schematic flow chart diagram illustrating one embodiment of a method for controlling a cryogenic two-stage pump according to the present invention;

FIG. 2 is a schematic flow chart illustrating one embodiment of determining a knock-down parameter of the cryogenic secondary pump in the method of the present invention;

FIG. 3 is a schematic flow chart illustrating one embodiment of a method of controlling operation of the cryogenic two-stage pump reduction system of the present invention;

FIG. 4 is a schematic flow chart illustrating one embodiment of determining the machining parameters of the secondary refrigeration pump in the method of the present invention;

FIG. 5 is a schematic flow chart illustrating one embodiment of a method of controlling operation of the cryogenic secondary pump;

FIG. 6 is a schematic diagram of a control device of the secondary refrigeration pump according to an embodiment of the present invention;

FIG. 7 is a schematic diagram of the refrigerant two-stage pump minus variable frequency conditioning logic of an embodiment of the air conditioning system of the present invention;

FIG. 8 is a schematic diagram of the refrigerant two-stage pump plus inverter conditioning logic of an embodiment of the air conditioning system of the present invention.

The reference numbers in the embodiments of the present invention are as follows, in combination with the accompanying drawings:

102-a detection unit; 104-a determination unit; 106-control unit.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the specific embodiments of the present invention and the accompanying drawings. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

According to an embodiment of the present invention, a method for controlling a refrigeration secondary pump is provided, as shown in fig. 1, which is a schematic flow diagram of an embodiment of the method of the present invention. The control method of the refrigeration two-stage pump comprises the following steps: step S110 to step S130.

In step S110, a variable frequency control input signal of the secondary refrigeration pump is collected, and a frequency and a head of the secondary refrigeration pump are obtained. Specifically, the frequency conversion control input signal of the refrigeration secondary pump of the air conditioning system may be collected, and the frequency and the lift of the refrigeration secondary pump of the air conditioning system may be obtained.

Determining a target frequency of the secondary refrigeration pump according to a variable frequency control input signal of the secondary refrigeration pump at step S120; and determining a machine subtracting parameter of the freezing secondary pump or a machine adding parameter of the freezing secondary pump according to the frequency of the freezing secondary pump and the lift of the freezing secondary pump.

In some embodiments, determining the target frequency of the secondary refrigeration pump according to the variable frequency control input signal of the secondary refrigeration pump in step S120 includes: and calculating the target frequency of the freezing secondary pump by adopting a freezing secondary pump frequency conversion control algorithm according to the frequency conversion control input signal of the freezing secondary pump. The frequency conversion control algorithm of the refrigeration secondary pump comprises the following steps: and a PID control algorithm of the freezing secondary pump frequency.

Specifically, a PID control algorithm for the freezing secondary pump frequency, such as a PID control method for the water pump frequency, may include: k is equal to Δ Hz_p(ΔE₀–ΔE_-1)+k_iΔE₀+k_d(ΔE₀–2ΔE_-1+ΔE_-2)。

And the target frequency of the water pump is equal to the current frequency of the water pump plus the frequency increment of the water pump. k is a radical of_p、k_i、k_dAnd the constants are proportional, integral and differential constants in sequence. Delta E₀The signal offset is input for the current control period. Delta E_-1The signal offset is input for the last control period. Delta E_-2The signal offset is input for the last two control periods.

At step S130, controlling the freezing secondary pump to operate in a reduced mode according to the target frequency of the freezing secondary pump and the reduced mode parameter of the freezing secondary pump; or controlling the machine adding operation of the freezing secondary pump according to the target frequency of the freezing secondary pump and the machine adding parameters of the freezing secondary pump.

Specifically, through confirming water pump plus-minus machine parameter, realize freezing secondary pump plus-minus machine's steady switching, prevent to appear the phenomenon that the water pump short time frequently opened and stop among the switching process, can further improve the operating efficiency of freezing secondary pump on the basis of guaranteeing freezing secondary pump reliable operation to improve the energy-conserving operation level of freezing secondary pump, also effectively improved freezing secondary pump frequency conversion control's energy-conservation nature and reliability.

In some embodiments, the subtracting parameter comprises: the maximum derating frequency of the freezing secondary pump and the target frequency after the freezing secondary pump is derated.

In step S120, a specific process of determining a machine reduction parameter of the secondary freezing pump according to the frequency of the secondary freezing pump and the head of the secondary freezing pump may be referred to as the following exemplary description.

The following further describes a specific process of determining the engine reduction parameter of the secondary refrigeration pump in step S120, with reference to a flowchart of an embodiment of determining the engine reduction parameter of the secondary refrigeration pump in the method of the present invention shown in fig. 2, and may include: step S210 to step S230.

Step S210, under the condition that the refrigerating secondary pump needs to be reduced, determining the flow of the refrigerating secondary pump by adopting the corresponding relation among the set flow, the set lift and the set frequency.

And step S220, determining the maximum machine reducing frequency of the freezing secondary pump according to the flow of the freezing secondary pump.

Specifically, by establishing a correlation function of the flow rate, the lift and the frequency of the water pump, a change rule is determined, and a water pump mathematical model is obtained, which may include: h ═ f (Hz, G). Wherein G is the water flow of the water pump. And f () is a mathematical functional relation, comprises various forms of mathematical formulas such as a polynomial and a Fourier series, and is obtained by fitting experimental data. Hz is the water pump frequency. H is the pump head.

And according to the frequency and the lift of the refrigeration secondary pump under the current working condition, the flow of the water pump under the current working condition can be calculated according to a water pump mathematical model. And calculating the maximum machine reducing frequency of the freezing secondary pump (namely the maximum machine reducing frequency of the freezing secondary pump) under the current working condition in real time.

More specifically, the maximum frequency that can exist for the post-pump secondary system is calculated to prevent the water pump from being frequently de-loaded. The calculation method of the maximum frequency of the refrigeration two-stage pump subtracting machine can comprise the following steps:

G_reducing＝G_{General assembly}/(N-1)；

G_{At present}＝G_{General assembly}/N；

H_{Maximum frequency}＝f(Hz_{Maximum frequency}，G_Reducing)；

H_{Maximum frequency}＝f(Hz_{Reducing the maximum frequency of the machine}，G_{At present})。

Wherein G is_ReducingAnd the target water flow of the refrigerating secondary pump after the machine reduction is realized. G_{At present}The flow of the water of the freezing secondary pump before the machine is reduced. G_{General assembly}To reduce the front of the machine orReducing the water flow of the main pipe of the post-freezing secondary pump system. And N is the online operation number of the front freezing secondary pump of the compressor. Hz_{Maximum frequency}The default value for the maximum frequency of the secondary refrigeration pump is 50 Hz. Hz_{Reducing the maximum frequency of the machine}And reducing the maximum frequency of the refrigerating secondary pump by iterative calculation. And f () is a mathematical functional relation, comprises various forms of mathematical formulas such as a polynomial and a Fourier series, and is obtained by fitting experimental data.

And step S230, determining the target frequency of the refrigerating secondary pump after the machine reduction according to the flow curve of the refrigerating secondary pump.

Specifically, the method for calculating the target frequency after the two-stage pump reduction in the freezing process may include: and calculating the target frequency of the water pump after the computer is subtracted according to the water pump curve. The method for calculating the target frequency of the water pump after the computer reduction according to the water pump curve can comprise the following steps:

G_reducing＝G_{General assembly}/(N-1)；

H_Meter＝f(Hz_{Reducing the target frequency of the machine}，G_Reducing)。

Wherein Hz is found by iterative calculation_{Reducing the target frequency of the machine}. The exit condition of the iterative computation is H_Meter-H, less than the control accuracy requirement. G_ReducingAnd the target water flow of the refrigerating secondary pump after the machine reduction is realized. G_{General assembly}The water flow of the main pipe of the refrigerating secondary pump system before or after the compressor is reduced. And N is the online operation number of the front freezing secondary pump of the compressor. H_MeterThe on-line freezing secondary pump lift in the iterative calculation process is calculated. H is the reduction of the front refrigeration secondary pump head. Hz_{Reducing the target frequency of the machine}To reduce the post-refrigeration secondary pump target frequency. And f () is a mathematical functional relation, comprises various forms of mathematical formulas such as a polynomial and a Fourier series, and is obtained by fitting experimental data. Through the algorithms, the stable switching of the refrigerating secondary pump adding and subtracting machine can be realized, and the phenomenon that the water pump is frequently started and stopped in a short time in the switching process is prevented.

In some embodiments, the specific process of the freezing secondary pump decreasing operation is controlled in step S130 according to the target frequency of the freezing secondary pump and the decreasing parameter of the freezing secondary pump, which includes the following two decreasing control processes.

The first subtracting machine control process: and after determining the target frequency of the freezing secondary pump after the machine reduction, changing the running frequency of an online freezing secondary pump in the freezing secondary pump into the target frequency of the freezing secondary pump after the machine reduction.

And a second subtracting control process: and controlling the actual control process of the operation of the refrigerating secondary pump by subtracting the machine according to the target frequency of the refrigerating secondary pump and the machine subtracting parameter of the refrigerating secondary pump.

The following further describes a specific process of controlling the operation of the freezing secondary pump in step S130, with reference to a schematic flow chart of an embodiment of controlling the operation of the freezing secondary pump in the method of the present invention shown in fig. 3, and the specific process may include: step S310 to step S330.

Step S310, determining whether the target frequency of the freezing secondary pump is less than the maximum machine reduction frequency of the freezing secondary pump.

Step S320, if the target frequency of the secondary freezing pump is less than the maximum machine reduction frequency of the secondary freezing pump, turning off an online secondary freezing pump with the longest operation time, and changing the operation frequency of the online secondary freezing pump in the secondary freezing pump to the target frequency after the machine reduction of the secondary freezing pump.

And step S330, if the target frequency of the secondary freezing pump is greater than or equal to the maximum machine reduction frequency of the secondary freezing pump, controlling the secondary freezing pump to change the running frequency.

Specifically, if the target frequency of the current water pump calculated by the variable frequency control algorithm is less than the maximum frequency of the engine, the water pump with the longest online accumulated running time is closed. After the freezing secondary pumps are reduced, all the online freezing secondary pumps are quickly loaded to the target frequency of the reduction machine. And if the target frequency of the current water pump calculated by the variable frequency control algorithm is greater than or equal to the maximum frequency of the refrigerator, changing the current operating frequency of the refrigerating secondary pump according to the target frequency of the water pump obtained by the variable frequency control algorithm.

In some embodiments, the machining parameters include: the minimum machining frequency of the freezing secondary pump and the target frequency of the freezing secondary pump after machining.

In step S130, a specific process of determining the machining parameter of the secondary freezing pump according to the frequency of the secondary freezing pump and the head of the secondary freezing pump may be referred to as the following exemplary description.

The following further describes a specific process of determining the machining parameter of the secondary refrigeration pump in step S120, with reference to a schematic flow chart of an embodiment of determining the machining parameter of the secondary refrigeration pump in the method of the present invention shown in fig. 4, and the specific process may include: step S410 to step S420.

And S410, under the condition that the refrigerating secondary pump needs to be added, determining the flow of the refrigerating secondary pump by adopting a corresponding relation among set flow, set lift and set frequency according to the frequency of the refrigerating secondary pump and the lift of the refrigerating secondary pump.

And step S420, determining the minimum machining frequency of the freezing secondary pump according to the flow of the freezing secondary pump. And the number of the first and second groups,

and step S430, determining the target frequency of the refrigerating secondary pump after the machine is added according to the flow curve of the refrigerating secondary pump.

The process for determining the machine adding parameter of the refrigerating secondary pump can be referred to as the process for determining the machine subtracting parameter of the refrigerating secondary pump.

Therefore, the water pump adding frequency is determined through the built-in water pump model, the problem of frequent adding of the freezing secondary pump is solved, meanwhile, the running frequency of the on-line freezing secondary pump is improved as much as possible, the running efficiency of the freezing secondary pump is kept in a high-efficiency area, and therefore the energy-saving running level of the freezing secondary pump is improved.

In some embodiments, the specific process of controlling the operation of the refrigerating secondary pump in step S130 according to the target frequency of the refrigerating secondary pump and the feeding parameters of the refrigerating secondary pump can be seen in the following exemplary description.

The following further describes a specific process of controlling the operation of the refrigerating secondary pump in step S130, with reference to a schematic flow chart of an embodiment of controlling the operation of the refrigerating secondary pump in the method of the present invention shown in fig. 5, and the specific process may include: step S510 to step S530.

Step S510, determining whether the target frequency of the secondary refrigeration pump is greater than the minimum machining frequency of the secondary refrigeration pump.

Step S520, if the target frequency of the freezing secondary pump is greater than the minimum machining frequency of the freezing secondary pump, starting an offline freezing secondary pump with the shortest calendar history running time, and changing the running frequency of the online freezing secondary pump in the freezing secondary pump into the target frequency after machining of the freezing secondary pump.

Step S530, if the target frequency of the freezing secondary pump is less than or equal to the minimum machining frequency of the freezing secondary pump, controlling the freezing secondary pump to change the running frequency.

Therefore, the water pump machine reduction frequency is determined through the built-in water pump model, the problem of frequent machine reduction of the freezing secondary pump is solved, meanwhile, the running frequency of the online freezing secondary pump is improved as much as possible, the running efficiency of the freezing secondary pump is kept in a high-efficiency area, and therefore the energy-saving running level of the freezing secondary pump is improved.

A large number of tests verify that the technical scheme of this embodiment is adopted, and through built-in water pump model, the frequency of adding the subtracting machine of water pump is confirmed, on the basis of guaranteeing the reliable operation of freezing second grade pump, further improves the operating efficiency of freezing second grade pump to promote energy-conserving effect.

According to an embodiment of the present invention, there is also provided a control apparatus of a freezing two-stage pump corresponding to a control method of the freezing two-stage pump. Referring to fig. 6, a schematic diagram of an embodiment of the apparatus of the present invention is shown. The control device of the refrigeration secondary pump may include: a detection unit 102, a determination unit 104 and a control unit 106.

The detection unit 102 is configured to acquire a variable frequency control input signal of the secondary refrigeration pump and acquire the frequency and the head of the secondary refrigeration pump. The specific function and processing of the detection unit 102 are shown in step S110. Specifically, the frequency conversion control input signal of the refrigeration secondary pump of the air conditioning system may be collected, and the frequency and the lift of the refrigeration secondary pump of the air conditioning system may be obtained.

A determining unit 104 configured to determine a target frequency of the cryogenic secondary pump based on a variable frequency control input signal of the cryogenic secondary pump; and determining a machine subtracting parameter of the freezing secondary pump or a machine adding parameter of the freezing secondary pump according to the frequency of the freezing secondary pump and the lift of the freezing secondary pump. The specific function and processing of the determination unit 104 are referred to in step S120.

In some embodiments, the determining unit 104, determining the target frequency of the secondary refrigeration pump according to the variable frequency control input signal of the secondary refrigeration pump, includes: the determining unit 104 is specifically further configured to calculate a target frequency of the secondary refrigeration pump by using a secondary refrigeration pump variable frequency control algorithm according to the variable frequency control input signal of the secondary refrigeration pump. The frequency conversion control algorithm of the refrigeration secondary pump comprises the following steps: and a PID control algorithm of the freezing secondary pump frequency.

Specifically, the PID control algorithm of the freezing secondary pump frequency, such as the water pump frequency PID control device, may include: k is equal to Δ Hz_p(ΔE₀–ΔE_-1)+k_iΔE₀+k_d(ΔE₀–2ΔE_-1+ΔE_-2)。

A control unit 106 configured to control the freezing secondary pump to run in a reduced mode according to a target frequency of the freezing secondary pump and a reduced mode parameter of the freezing secondary pump; or controlling the machine adding operation of the freezing secondary pump according to the target frequency of the freezing secondary pump and the machine adding parameters of the freezing secondary pump. The specific function and processing of the control unit 106 are shown in step S130.

The determining unit 104 determines the machine reduction parameter of the secondary freezing pump according to the frequency of the secondary freezing pump and the head of the secondary freezing pump, and includes:

the determining unit 104 is specifically further configured to determine the flow rate of the secondary refrigeration pump by using a corresponding relationship among a set flow rate, a set head and a set frequency in a case that the secondary refrigeration pump needs to be reduced. The specific function and processing of the determination unit 104 are also referred to in step S210.

The determining unit 104 is specifically further configured to determine a maximum derating frequency of the secondary refrigeration pump according to the flow rate of the secondary refrigeration pump. The specific function and processing of the determination unit 104 are also referred to in step S220.

G_reducing＝G_{General assembly}/(N-1)；

G_{At present}＝G_{General assembly}/N；

H_{Maximum frequency}＝f(Hz_{Maximum frequency}，G_Reducing)；

Wherein G is_ReducingAnd the target water flow of the refrigerating secondary pump after the machine reduction is realized. G_{At present}The flow of the water of the freezing secondary pump before the machine is reduced. G_{General assembly}The water flow of the main pipe of the refrigerating secondary pump system before or after the compressor is reduced. And N is the online operation number of the front freezing secondary pump of the compressor. Hz_{Maximum frequency}The default value for the maximum frequency of the secondary refrigeration pump is 50 Hz. Hz_{Reducing the maximum frequency of the machine}And reducing the maximum frequency of the refrigerating secondary pump by iterative calculation. And f () is a mathematical functional relation, comprises various forms of mathematical formulas such as a polynomial and a Fourier series, and is obtained by fitting experimental data.

The determining unit 104 is specifically further configured to determine the target frequency of the secondary freezing pump after the secondary freezing pump is turned off according to the flow curve of the secondary freezing pump. The specific function and processing of the determination unit 104 are also referred to in step S230.

Specifically, the target frequency calculation device after the two-stage pump reduction in the freezing process may include: and calculating the target frequency of the water pump after the computer is subtracted according to the water pump curve. The device for calculating the target frequency of the water pump after the computer reduction according to the water pump curve can comprise:

G_reducing＝G_{General assembly}/(N-1)；

H_Meter＝f(Hz_{Reducing the target frequency of the machine}，G_Reducing)。

In some embodiments, the control unit 106 controls the operation of the two-stage chiller pump based on the target frequency of the two-stage chiller pump and the derating parameter of the two-stage chiller pump, including the following two derating control processes:

the first subtracting machine control process: the control unit 106 is specifically further configured to, after determining the target frequency of the freeze secondary pump after the shutdown, change the operating frequency of the online freeze secondary pump in the freeze secondary pump to the target frequency of the freeze secondary pump after the shutdown. And the number of the first and second groups,

and a second subtracting control process: the control unit 106 controls an actual control process of the operation of the secondary refrigeration pump according to the target frequency of the secondary refrigeration pump and the machine reduction parameter of the secondary refrigeration pump, which may specifically be as follows:

the control unit 106 is further specifically configured to determine whether the target frequency of the cryogenic secondary pump is less than a maximum derating frequency of the cryogenic secondary pump. The specific functions and processes of the control unit 106 are also referred to in step S310.

The control unit 106 is specifically further configured to, if the target frequency of the freezing secondary pump is less than the maximum shutdown frequency of the freezing secondary pump, shut down an online freezing secondary pump with the longest operation time, and change the operation frequency of the online freezing secondary pump in the freezing secondary pumps to the target frequency after shutdown of the freezing secondary pump. The specific functions and processes of the control unit 106 are also referred to in step S320.

The control unit 106 is further specifically configured to control the secondary refrigeration pump to change the operating frequency if the target frequency of the secondary refrigeration pump is greater than or equal to the maximum minus machine frequency of the secondary refrigeration pump. The specific function and processing of the control unit 106 are also referred to in step S330.

The determining unit 104 determines the machining parameters of the secondary freezing pump according to the frequency of the secondary freezing pump and the head of the secondary freezing pump, and includes:

the determining unit 104 is specifically further configured to determine, according to the frequency of the secondary freezing pump and the lift of the secondary freezing pump, the flow rate of the secondary freezing pump by using a corresponding relationship between a set flow rate, a set lift and a set frequency, when the secondary freezing pump needs to be added. The specific function and processing of the determination unit 104 are also referred to in step S410.

The determining unit 104 is specifically further configured to determine a minimum adding frequency of the secondary freezing pump according to the flow rate of the secondary freezing pump. The specific function and processing of the determination unit 104 are also referred to step S420.

And determining the target frequency of the refrigerating secondary pump after the machine is added according to the flow curve of the refrigerating secondary pump. The specific function and processing of the determination unit 104 are also referred to in step S430.

In some embodiments, the control unit 106, controlling the operation of the refrigeration secondary pump according to the target frequency of the refrigeration secondary pump and the feeding parameters of the refrigeration secondary pump, includes:

the control unit 106 is further specifically configured to determine whether the target frequency of the cryogenic secondary pump is greater than a minimum ramp frequency of the cryogenic secondary pump. The specific functions and processes of the control unit 106 are also referred to in step S510.

The control unit 106 is further specifically configured to, if the target frequency of the secondary freezing pumps is greater than the minimum adding frequency of the secondary freezing pumps, start an off-line secondary freezing pump with the shortest calendar history running time, and change the running frequency of an on-line secondary freezing pump in the secondary freezing pumps to the target frequency after the secondary freezing pump is added. The specific function and processing of the control unit 106 are also referred to in step S520.

The control unit 106 is further specifically configured to control the secondary refrigeration pump to change the operating frequency if the target frequency of the secondary refrigeration pump is less than or equal to the minimum machining frequency of the secondary refrigeration pump. The specific functions and processes of the control unit 106 are also referred to in step S530.

Since the processes and functions implemented by the apparatus of this embodiment substantially correspond to the embodiments, principles and examples of the method shown in fig. 1 to 5, the description of this embodiment is not detailed, and reference may be made to the related descriptions in the foregoing embodiments, which are not repeated herein.

A large number of tests prove that the technical scheme of the invention determines the frequency of the water pump plus-minus machine through the built-in water pump model, and can effectively improve the energy conservation and the reliability of the frequency conversion control of the refrigeration secondary pump.

According to an embodiment of the present invention, there is also provided an air conditioning system corresponding to a control device of a refrigerating secondary pump. The air conditioning system may include: the control device of the refrigerating two-stage pump.

With the increasing maturity of variable frequency technology, the demand of variable frequency control of the refrigeration secondary pump is also increasing. In the related scheme, the control mode of the secondary pump is controlled according to the pressure difference of a water supply main pipe and a water return main pipe of the secondary pump; the change of the flow of the chilled water is controlled through the change of the number of the secondary pumps, the flow of the chilled water has step-like sudden change, and fine adjustment is carried out through a main pipe bypass valve. In the related scheme, the flow rate of the water pump is suddenly changed whether the frequency is changed or not. The generation reason is caused by a water pump principle.

In some embodiments, the scheme of the invention provides a method and a device for controlling the variable frequency of a refrigeration secondary pump, which can further improve the operation efficiency of the refrigeration secondary pump on the basis of ensuring the reliable operation of the refrigeration secondary pump, thereby improving the energy-saving operation level of the refrigeration secondary pump and effectively improving the energy-saving performance and the reliability of the variable frequency control of the refrigeration secondary pump.

The scheme of the invention provides a variable frequency control method of a refrigerating secondary pump and an adding and subtracting machine control method for parallel operation of a plurality of refrigerating secondary pumps, determines the adding and subtracting machine frequency of a water pump through a built-in water pump model, solves the problem that the service life of equipment is influenced by frequent adding and subtracting of the refrigerating secondary pump, improves the operation frequency of the on-line refrigerating secondary pump as far as possible, and keeps the operation efficiency of the refrigerating secondary pump in a high-efficiency area, thereby improving the energy-saving operation level of the refrigerating secondary pump.

In some embodiments, the control algorithm involved in the aspects of the present invention may include: and (4) establishing a related function of the flow, the lift and the frequency of the water pump, and determining a change rule.

Specifically, the water pump mathematical model may include: h ═ f (Hz, G).

Wherein G is the water flow of the water pump. And f () is a mathematical functional relation, comprises various forms of mathematical formulas such as a polynomial and a Fourier series, and is obtained by fitting experimental data. Hz is the water pump frequency. H is the pump head.

In some embodiments, the variable frequency control algorithm of the refrigeration secondary pump involved in the aspect of the present invention may include: and a water pump frequency PID control method.

Specifically, the water pump frequency PID control method may include:

ΔHz＝k_p(ΔE₀–ΔE_-1)+k_iΔE₀+k_d(ΔE₀–2ΔE_-1+ΔE_-2)。

In some embodiments, the method for calculating the target frequency after the two-stage pump cooling in the aspect of the present invention may include: and calculating the target frequency of the water pump after the computer is subtracted according to the water pump curve.

Specifically, the method for calculating the target frequency of the water pump after the computer reduction according to the water pump curve may include:

G_reducing＝G_{General assembly}/(N-1)；

H_Meter＝f(Hz_{Reducing the target frequency of the machine}，G_Reducing)。

Wherein Hz is found by iterative calculation_{Reducing the target frequency of the machine}. The exit condition of the iterative computation is H_Meter-H, less than the control accuracy requirement.

For example: suppose a subtract onlineTarget frequency H of water pump_{z minus machine target frequency}Calculated at G according to the above formula_ReducingAnd H_{z minus machine target frequency}H_MeterCalculating H_Meter-H is less than the calculated error set point, if yes, the iterative calculation process is exited, otherwise the previous three steps are continued.

G_ReducingAnd the target water flow of the refrigerating secondary pump after the machine reduction is realized. G_{General assembly}The water flow of the main pipe of the refrigerating secondary pump system before or after the compressor is reduced. And N is the online operation number of the front freezing secondary pump of the compressor. H_MeterThe on-line freezing secondary pump lift in the iterative calculation process is calculated. H is the reduction of the front refrigeration secondary pump head. Hz_{Reducing the target frequency of the machine}To reduce the post-refrigeration secondary pump target frequency. And f () is a mathematical functional relation, comprises various forms of mathematical formulas such as a polynomial and a Fourier series, and is obtained by fitting experimental data.

In some embodiments, the calculation of the maximum frequency of the refrigeration secondary pump minus machine involved in the solution of the present invention may include: and calculating the maximum frequency of the secondary pump system after the reduction of the computer to prevent the water pump from frequently loading and unloading.

Specifically, the calculation method of the maximum frequency of the refrigeration secondary pump minus machine may include:

G_reducing＝G_{General assembly}/(N-1)；

G_{At present}＝G_{General assembly}/N；

H_{Maximum frequency}＝f(Hz_{Maximum frequency}，G_Reducing)；

Wherein G is_ReducingAnd the target water flow of the refrigerating secondary pump after the machine reduction is realized. G_{At present}The flow of the water of the freezing secondary pump before the machine is reduced. G_{General assembly}The water flow of the main pipe of the refrigerating secondary pump system before or after the compressor is reduced. And N is the online operation number of the front freezing secondary pump of the compressor. Hz_{Maximum frequency}The default value for the maximum frequency of the secondary refrigeration pump is 50 Hz. Hz_{Reducing the maximum frequency of the machine}And reducing the maximum frequency of the refrigerating secondary pump by iterative calculation. f () is a numberThe mathematical function relational expression comprises various forms of mathematical formulas such as a polynomial expression, a Fourier series and the like, and is obtained by fitting experimental data.

Through the algorithms, the stable switching of the refrigerating secondary pump adding and subtracting machine can be realized, and the phenomenon that the water pump is frequently started and stopped in a short time in the switching process is prevented.

In some embodiments, the control strategy in the solution of the present invention may include:

step 1, according to the frequency and the lift of the refrigeration secondary pump under the current working condition, the flow of the water pump under the current working condition can be calculated according to a water pump mathematical model.

The current working condition is an actual operating working condition, and refers to the water pump frequency and the lift of the water pump in actual operation.

And 2, calculating the maximum machine reduction frequency of the refrigerating secondary pump under the current working condition in real time (namely the maximum machine reduction frequency of the refrigerating secondary pump).

Optionally, if the target frequency of the current water pump calculated by the variable frequency control algorithm is less than the maximum frequency of the engine, the water pump with the longest online accumulated running time is turned off. After the freezing secondary pumps are reduced, all the online freezing secondary pumps are quickly loaded to the target frequency of the reduction machine.

Optionally, if the target frequency of the current water pump calculated by the variable frequency control algorithm is greater than or equal to the maximum frequency of the refrigerator, the current operating frequency of the refrigeration secondary pump is changed according to the target frequency of the water pump calculated by the variable frequency control algorithm.

The following describes an exemplary implementation process of the scheme of the present invention with reference to the examples shown in fig. 7 and fig. 8.

FIG. 7 is a schematic diagram of the chiller two-stage pump minus inverter frequency modulation logic of an embodiment of the air conditioning system of the present invention. As shown in fig. 7, the process of frequency conversion adjustment of the two-stage pump-reduction refrigeration machine includes:

step 11, collecting input signals of water pump frequency conversion control, and executing step 12; and the frequency and the head of the refrigerating secondary pump are detected, and step 13 is executed.

The variable frequency control input signal of the water pump can be specifically temperature difference or pressure difference, and the target frequency of the water pump can be calculated according to a control algorithm through the difference between the input signal and a set value.

And 12, calculating the obtained target frequency of the current water pump by adopting a refrigeration secondary pump variable frequency control algorithm according to the acquired variable frequency control input signal of the water pump, and executing the step 14.

And step 13, calculating the maximum machine reduction frequency of the freezing secondary pump by adopting a freezing secondary pump mathematical model according to the detected frequency and the detected lift of the freezing secondary pump, and executing step 14.

Meanwhile, according to the detected frequency and lift of the freezing secondary pump, calculating the target frequency of the freezing secondary pump after the machine reduction by adopting a mathematical model of the freezing secondary pump, and executing the step 15.

After the target frequency after the machine reduction is determined, the freezing secondary pump is directly controlled to change the running frequency of the online pump according to the target frequency after the machine reduction, so that the total water flow before and after the machine reduction can be maintained as much as possible, and the occurrence of huge fluctuation is avoided.

And 14, judging whether the target frequency of the freezing secondary pump is less than the maximum machine reducing frequency of the freezing secondary pump or not, if so, closing the online freezing secondary pump with the longest operation time, and executing the step 15. And if the target frequency of the freezing secondary pump is greater than or equal to the maximum machine reducing frequency of the freezing secondary pump, controlling the freezing secondary pump to change the running frequency.

Wherein, subtract quick-witted in-process, control freezing secondary pump and change operating frequency can include: the group control controller changes the target frequency of the water pump frequency converter by controlling output, and the frequency converter changes the running frequency of the water pump according to the inherent control of the frequency converter.

And step 15, controlling the refrigerating secondary pump to change the running frequency of the online pump according to the target frequency of the reduction machine.

FIG. 8 is a schematic diagram of the refrigerant two-stage pump plus inverter conditioning logic of an embodiment of the air conditioning system of the present invention. As shown in fig. 8, the refrigerating two-stage pump-adding frequency conversion adjusting process includes:

step 21, collecting a variable frequency control input signal of the water pump, and executing step 22; and the frequency and the head of the secondary refrigeration pump are detected, and step 23 is executed.

And step 22, calculating the obtained target frequency of the current water pump by adopting a refrigeration secondary pump frequency conversion control algorithm according to the acquired input signal of the water pump frequency conversion control, and executing step 24.

And 23, calculating the minimum machining frequency of the freezing secondary pump by adopting a freezing secondary pump mathematical model according to the detected frequency and the detected lift of the freezing secondary pump, and executing the step 24.

Meanwhile, according to the detected frequency and lift of the freezing secondary pump, a mathematical model of the freezing secondary pump is adopted to calculate the target frequency of the freezing secondary pump after the machine is added, and step 24 is executed.

And 24, judging whether the target frequency of the freezing secondary pump is greater than the minimum adding frequency of the freezing secondary pump, if so, starting the online freezing secondary pump with the shortest accumulated running time, and controlling the freezing secondary pump to change the running frequency of the online pump according to the adding target frequency. And if the target frequency of the freezing secondary pump is less than or equal to the minimum machining frequency of the freezing secondary pump, controlling the freezing secondary pump to change the running frequency.

Since the processing and functions of the air conditioning system of this embodiment are basically corresponding to the embodiments, principles and examples of the apparatus shown in fig. 6, the description of this embodiment is not given in detail, and reference may be made to the related descriptions in the embodiments, which are not described herein again.

Through a large number of tests, the technical scheme of the invention determines the frequency of the water pump adding and subtracting machine through the built-in water pump model, and improves the energy-saving operation level under the condition of ensuring the stable switching of the refrigerating secondary pump adding and subtracting machine.

According to an embodiment of the present invention, there is also provided a storage medium corresponding to a control method of a refrigerating secondary pump, the storage medium including a stored program, wherein when the program is executed, an apparatus in which the storage medium is controlled performs the control method of the refrigerating secondary pump described above.

Since the processing and functions implemented by the storage medium of this embodiment substantially correspond to the embodiments, principles, and examples of the methods shown in fig. 1 to fig. 5, details are not described in the description of this embodiment, and reference may be made to the related descriptions in the foregoing embodiments, which are not described herein again.

Through a large number of tests, the technical scheme of the invention determines the frequency of the water pump adding and subtracting machine through the built-in water pump model, can realize the stable switching of the freezing secondary pump adding and subtracting machine, and prevents the phenomenon that the water pump is frequently started and stopped in a short time in the switching process.

There is also provided, in accordance with an embodiment of the present invention, a processor corresponding to a method of controlling a cryogenic secondary pump, the processor being configured to execute a program, wherein the program is configured to execute the method of controlling a cryogenic secondary pump described above.

Since the processing and functions implemented by the processor of this embodiment substantially correspond to the embodiments, principles, and examples of the methods shown in fig. 1 to fig. 5, details are not described in the description of this embodiment, and reference may be made to the related descriptions in the foregoing embodiments, which are not described herein again.

Through a large number of tests, the technical scheme of the invention determines the frequency of the water pump plus-minus machine through the built-in water pump model, improves the running frequency of the on-line freezing secondary pump, and keeps the running efficiency of the freezing secondary pump in a high-efficiency area, thereby improving the energy-saving running level of the freezing secondary pump.

In summary, it is readily understood by those skilled in the art that the advantageous modes described above can be freely combined and superimposed without conflict.

The above description is only an example of the present invention, and is not intended to limit the present invention, and it is obvious to those skilled in the art that various modifications and variations can be made in the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A method of controlling a cryogenic two-stage pump, comprising:

collecting a variable frequency control input signal of the refrigeration secondary pump, and acquiring the frequency and the lift of the refrigeration secondary pump;

determining a target frequency of the freezing secondary pump according to a variable frequency control input signal of the freezing secondary pump; determining a machine subtracting parameter of the freezing secondary pump or a machine adding parameter of the freezing secondary pump according to the frequency of the freezing secondary pump and the lift of the freezing secondary pump;

controlling the refrigerating secondary pump to operate in a machine reducing mode according to the target frequency of the refrigerating secondary pump and the machine reducing parameter of the refrigerating secondary pump; or controlling the machine adding operation of the freezing secondary pump according to the target frequency of the freezing secondary pump and the machine adding parameters of the freezing secondary pump.

2. The method of claim 1, wherein determining a target frequency of the cryogenic secondary pump based on a variable frequency control input signal to the cryogenic secondary pump comprises:

calculating the target frequency of the freezing secondary pump by adopting a freezing secondary pump variable frequency control algorithm according to the variable frequency control input signal of the freezing secondary pump; the frequency conversion control algorithm of the refrigeration secondary pump comprises the following steps: and a PID control algorithm of the freezing secondary pump frequency.

3. The method of controlling a cryogenic secondary pump according to claim 1 or 2, wherein the derating parameter comprises: the maximum machine reducing frequency of the freezing secondary pump and the target frequency of the freezing secondary pump after machine reduction;

determining a machine reduction parameter of the freezing secondary pump according to the frequency of the freezing secondary pump and the lift of the freezing secondary pump, wherein the machine reduction parameter comprises the following steps:

under the condition that the refrigerating secondary pump needs to be reduced, determining the flow of the refrigerating secondary pump by adopting a corresponding relation among set flow, set lift and set frequency;

determining the maximum machine reducing frequency of the freezing secondary pump according to the flow of the freezing secondary pump;

and determining the target frequency of the refrigerating secondary pump after the machine reduction according to the flow curve of the refrigerating secondary pump.

4. The method of claim 3, wherein controlling the cryosecondary pump derate operation based on the target frequency of the cryosecondary pump and the derate parameter of the cryosecondary pump comprises:

after the target frequency of the freezing secondary pump after the machine reduction is determined, changing the running frequency of an online freezing secondary pump in the freezing secondary pump into the target frequency of the freezing secondary pump after the machine reduction; and the number of the first and second groups,

determining whether a target frequency of the cryogenic secondary pump is less than a maximum derating frequency of the cryogenic secondary pump;

if the target frequency of the freezing secondary pump is less than the maximum machine reducing frequency of the freezing secondary pump, closing an online freezing secondary pump with the longest operation time, and changing the operation frequency of the online freezing secondary pump in the freezing secondary pump into the target frequency after the machine reduction of the freezing secondary pump;

and if the target frequency of the secondary freezing pump is greater than or equal to the maximum machine reducing frequency of the secondary freezing pump, controlling the secondary freezing pump to change the operating frequency.

5. The method of controlling a cryogenic secondary pump according to claim 1 or 2, wherein the machining parameters include: the minimum machining frequency of the freezing secondary pump and the target frequency of the freezing secondary pump after machining;

determining the machining parameters of the freezing secondary pump according to the frequency of the freezing secondary pump and the lift of the freezing secondary pump, wherein the machining parameters comprise:

under the condition that the refrigerating secondary pump needs to be added, determining the flow of the refrigerating secondary pump by adopting a corresponding relation among set flow, set lift and set frequency according to the frequency of the refrigerating secondary pump and the lift of the refrigerating secondary pump;

determining the minimum adding frequency of the freezing secondary pump according to the flow of the freezing secondary pump; and the number of the first and second groups,

and determining the target frequency of the refrigerating secondary pump after the machine is added according to the flow curve of the refrigerating secondary pump.

6. The method for controlling a cryogenic secondary pump according to claim 5, wherein controlling the cryogenic secondary pump to operate according to a target frequency of the cryogenic secondary pump and a machine parameter of the cryogenic secondary pump comprises:

determining whether a target frequency of the cryogenic secondary pump is greater than a minimum pump-up frequency of the cryogenic secondary pump;

if the target frequency of the freezing secondary pump is greater than the minimum adding frequency of the freezing secondary pump, starting an offline freezing secondary pump with the shortest calendar history running time, and changing the running frequency of the online freezing secondary pump in the freezing secondary pump into the target frequency of the freezing secondary pump after adding the machine;

and if the target frequency of the freezing secondary pump is less than or equal to the minimum machining frequency of the freezing secondary pump, controlling the freezing secondary pump to change the operating frequency.

7. A control apparatus for a cryogenic two-stage pump, comprising:

the detection unit is configured to collect a variable frequency control input signal of the refrigeration secondary pump and acquire the frequency and the lift of the refrigeration secondary pump;

a determination unit configured to determine a target frequency of the cryogenic secondary pump from a variable frequency control input signal of the cryogenic secondary pump; determining a machine subtracting parameter of the freezing secondary pump or a machine adding parameter of the freezing secondary pump according to the frequency of the freezing secondary pump and the lift of the freezing secondary pump;

a control unit configured to control the freezing secondary pump to run in a reduced mode according to a target frequency of the freezing secondary pump and a reduced mode parameter of the freezing secondary pump; or controlling the machine adding operation of the freezing secondary pump according to the target frequency of the freezing secondary pump and the machine adding parameters of the freezing secondary pump.

8. The apparatus as claimed in claim 7, wherein the determining unit determines the target frequency of the secondary refrigeration pump based on a variable frequency control input signal of the secondary refrigeration pump, comprising:

9. The control device of a cryogenic secondary pump according to claim 7 or 8, wherein the derating parameter comprises: the maximum machine reducing frequency of the freezing secondary pump and the target frequency of the freezing secondary pump after machine reduction;

the determining unit determines a machine reduction parameter of the freezing secondary pump according to the frequency of the freezing secondary pump and the head of the freezing secondary pump, and comprises the following steps:

10. The apparatus of claim 9, wherein the control unit controls the cryosecondary pump to run down according to a target frequency of the cryosecondary pump and a down parameter of the cryosecondary pump, comprising:

11. The control device of a cryogenic secondary pump according to claim 7 or 8, wherein the machining parameters include: the minimum machining frequency of the freezing secondary pump and the target frequency of the freezing secondary pump after machining;

the determining unit determines the machining parameters of the freezing secondary pump according to the frequency of the freezing secondary pump and the head of the freezing secondary pump, and comprises the following steps:

12. The apparatus as claimed in claim 11, wherein the control unit controls the operation of the secondary refrigeration pump according to the target frequency of the secondary refrigeration pump and the operational parameters of the secondary refrigeration pump, comprising:

13. An air conditioning system, comprising: control means for a cryogenic secondary pump according to any one of claims 7 to 12.

14. A storage medium comprising a stored program, wherein the program, when executed, controls an apparatus in which the storage medium is located to perform the method of controlling a cryogenic secondary pump of any of claims 1 to 6.

15. A processor, characterized in that the processor is configured to run a program, wherein the program when running performs the method of controlling a cryogenic secondary pump according to any one of claims 1 to 6.