Energy-saving control method for air conditioning unit

Abstract

The present invention discloses an energy-saving control method for an air-conditioning unit, including preprocessing historical data and storing it; establishing a water pump energy consumption estimation model; taking the actual power P of a single water pump a as the dependent variable, and the independent variables being the water pump operating frequency F and the rated power P of the water pump e ; fitting to determine the actual value of c, and the default value of c is 2.8, c = 2.8; calculating the total power; based on the water pump energy consumption estimation model, calculating the total power of a single water pump to N water pumps within the upper and lower limits of the operating frequency respectively, determining the switching critical frequency of the water pump parallel connection, and generating a water pump operating energy consumption library; during actual operation, taking the total power P t to be the lowest as the goal, traversing and querying the water pump energy consumption library to confirm the number of water pumps to be turned on and the set value of the water pump operating frequency. The present invention is easy to implement, has low requirements for monitoring and calculation capabilities, and can balance economy and practicability in engineering practice.

Description

Technical Field

[0001] The present invention relates to the technical field of insulation installation of power modules in rail transit industry related equipment, and in particular to an energy-saving control method for an air-conditioning unit. Background Art

[0002] In the central air-conditioning system, the water pump is mainly used as a power device to provide power for the air-conditioning water supply system. The safe, normal and stable operation of the water pump has a great impact on the energy consumption of the entire central air-conditioning water system. The water pump start and stop, frequency conversion and other adjustment methods involved in the normal operation of the water pump directly affect the energy saving effect during the normal operation of the water pump. In the initial selection and design, the water pump is designed according to the maximum load and redundancy is considered. However, the load during actual operation is much lower than the design load most of the time. Therefore, the variable water flow control based on the water pump frequency conversion shows a strong energy-saving effect and gradually develops into the main adjustment method.

[0003] However, when performing frequency conversion control on multiple water pumps in parallel, the previous method was to increase the frequency of one pump to the upper limit before loading the next one during loading; and to reduce the frequency of one pump to the lower limit before reducing the load during load reduction. From the perspective of energy consumption, although this method can basically meet the terminal flow requirements, there is still room for energy saving for the water pump system. Summary of the invention

[0004] 1. Technical problems to be solved:

[0005] In view of the above technical problems, the present invention provides an energy-saving control method for an air-conditioning unit, which quantitatively determines the number and frequency of running water pumps, optimizes the energy consumption of multiple water pumps of the same model running in parallel, and shortens the time required to find the optimal operating condition of the unit.

[0006] 2. Technical solution:

[0007] An energy-saving control method for an air-conditioning unit optimizes the parallel water pumps of the air-conditioning system; the method is characterized in that it comprises the following steps:

[0008] Step 1: Data processing; obtaining historical data and rated parameters of each parallel water pump of the air conditioning system; the historical data includes the water pump operating frequency F, actual power P a The rated parameters of the pump include rated power P e , rated frequency F e ; Pre-process the historical data and store it;

[0009] Step 2: Establish a water pump energy consumption estimation model; take the actual power P of a single water pump as a As the dependent variable, the independent variables are the pump operating frequency F and the pump rated power P e ; Substitute the data preprocessed in step 1 into the following formula:

[0010]

[0011] The actual value of c is determined by fitting, and the default value of c is 2.8c=2.8;

[0012] In actual operation, multiple inverters are adjusted simultaneously with equal frequencies, and the total power Pt is as follows:

[0013] P t =N*P a (2);

[0014] In formula (2), N represents the number of air conditioners, which is greater than or equal to 1;

[0015] Step 3: Based on the water pump energy consumption estimation model, the total power of a single water pump, two water pumps, and even N water pumps within the upper and lower limits of the operating frequency is calculated respectively, and the critical switching frequency of the water pumps in parallel is determined, thereby forming a water pump operation energy consumption library; the water pump energy consumption library includes the number of running water pumps, the corresponding operating frequency, and the corresponding total power;

[0016] Step 4: During actual operation, the total power P t With the lowest value as the goal, the water pump energy consumption database is traversed and queried to confirm the number of water pumps turned on and the set value of the water pump operating frequency, while satisfying the constraint condition of "number of chillers turned on ≤ number of water pumps turned on < number of chillers turned on + 2".

[0017] Furthermore, the critical switching frequency of the water pumps in parallel in step three is determined as follows: based on the water pump operation energy consumption library, when M water pumps are switched to M+1 pumps in parallel operation, the critical energy consumption of the M+1 water pump is the energy consumption of the M+1 pump at its lower limit frequency; then, the critical frequency of the M water pumps is calculated based on the energy consumption of the M+1 water pump at its lower limit frequency; M+1≤N.

[0018] Furthermore, the confirmation of the number of water pumps turned on and the water pump operating frequency setting value in step 4 are determined according to the switching critical frequency range when the water pumps are connected in parallel.

[0019] Furthermore, it also includes updating the water pump energy consumption estimation model; the water pump energy consumption estimation model is updated to update the historical data at a preset frequency, and the updated data is brought into step one to obtain the water pump energy consumption estimation model corresponding to the latest data.

[0020] 3. Beneficial effects:

[0021] This solution provides a method for optimizing the parallel operation of variable frequency water pumps of the same model in an air-conditioning system based on an energy consumption estimation model. The water pump energy consumption model and energy consumption library corresponding to the air-conditioning system are obtained through historical data. In the actual application process, the number and frequency of water pumps can be automatically adjusted to keep the overall energy consumption level of the water pump system at a low level. This solution is easy to implement, has low requirements for monitoring and computing capabilities, and can take into account both economy and practicality in actual engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0023] The present invention will be described in detail below with reference to the accompanying drawings.

[0024] As attached Figure 1 An energy-saving control method for an air-conditioning unit, characterized in that it comprises the following steps:

[0025] Step 1: Data processing; obtaining historical data and rated parameters of each parallel water pump of the air conditioning system; the historical data includes the water pump operating frequency F, actual power P a The rated parameters of the pump include rated power P e , rated frequency F e ; Pre-process the historical data and store it;

[0026] Step 2: Establish a water pump energy consumption estimation model; take the actual power P of a single water pump as a As the dependent variable, the independent variables are the pump operating frequency F and the pump rated power P e ; Substitute the data preprocessed in step 1 into the following formula:

[0027]

[0028] The actual value of c is determined by fitting, and the default value of c is 2.8c=2.8;

[0029] In actual operation, multiple inverters are adjusted simultaneously with equal frequencies, and the total power Pt is as follows:

[0030] P t =N*P a (2);

[0031] In formula (2), N represents the number of air conditioners, which is greater than or equal to 1;

[0032] Step 3: Based on the water pump energy consumption estimation model, the total power of a single water pump, two water pumps, and even N water pumps within the upper and lower limits of the operating frequency is calculated respectively, and the critical switching frequency of the water pumps in parallel is determined, thereby forming a water pump operation energy consumption library; the water pump energy consumption library includes the number of running water pumps, the corresponding operating frequency, and the corresponding total power;

[0033] Step 4: During actual operation, the total power P t With the lowest value as the goal, the water pump energy consumption database is traversed and queried to confirm the number of water pumps turned on and the set value of the water pump operating frequency, while satisfying the constraint condition of "number of chillers turned on ≤ number of water pumps turned on < number of chillers turned on + 2".

[0034] Furthermore, the critical switching frequency of the water pumps in parallel in step three is determined as follows: based on the water pump operation energy consumption library, when M water pumps are switched to M+1 pumps in parallel operation, the critical energy consumption of the M+1 water pump is the energy consumption of the M+1 pump at its lower limit frequency; then, the critical frequency of the M water pumps is calculated based on the energy consumption of the M+1 water pump at its lower limit frequency; M+1≤N.

[0035] Furthermore, the confirmation of the number of water pumps turned on and the water pump operating frequency setting value in step 4 are determined according to the switching critical frequency range when the water pumps are connected in parallel.

[0036] Furthermore, it also includes updating the water pump energy consumption estimation model; the water pump energy consumption estimation model is updated to update the historical data at a preset frequency, and the updated data is brought into step one to obtain the water pump energy consumption estimation model corresponding to the latest data. Specific embodiment:

[0038] For a certain type of centrifugal pump, with a rated power of 55KW, a rated frequency of 50Hz, and 3 pumps, the energy-saving control purpose can be achieved by adjusting the number of running pumps and the operating frequency.

[0039] The method and steps for optimizing the control of water pump energy saving are as follows:

[0040] 1) Fit the water pump energy consumption estimation model based on historical data and water pump rated parameters;

[0041] Among them, historical data includes the pump operating frequency F; rated parameters include rated power P e , rated frequency F e ; The independent variables of the energy consumption model are the pump operating frequency F and the pump rated power P e , the dependent variable is the actual power P of a single pump a ; The relationship between them is as follows:

[0042]

[0043] In actual operation, multiple inverters are adjusted simultaneously, the frequency remains consistent, and the total power is:

[0044] P t =N*P a (2)

[0045] 2) Based on the water pump energy consumption estimation model, calculate the total power of a single water pump, two water pumps, and three water pumps within the upper and lower limits of the operating frequency, determine the critical value, and form a water pump operation energy consumption library as follows:

[0046]

[0047] 3) During actual operation, P t The lowest value is the goal. The water pump energy consumption database is queried to confirm the number of water pumps turned on and the water pump operating frequency setting value. Here, the frequency upper limit value is 50Hz and the lower limit value is 30Hz.

[0048] When a chiller is turned on, the critical switching frequency between one water pump and two water pumps is 38.42Hz for one water pump and 30Hz for two water pumps. That is, when the frequency of one water pump is below 38.42Hz, one water pump is maintained in operation; when the frequency is above 38.42Hz, the two water pumps operation mode is adopted.

[0049] When two chillers are turned on, the critical point for switching between two water pumps and three water pumps is 34.67Hz for two water pumps and 30Hz for three water pumps. That is, when the two water pumps are between 30Hz and 34.67Hz, the two water pumps operating mode is maintained to meet the constraint of "number of chillers turned on ≤ number of water pumps turned on < number of chillers turned on + 2".

[0050] In this embodiment, the water pump switching critical value and energy consumption library are obtained based on the water pump energy consumption estimation model, the number and frequency of water pump operation are given in a quantitative manner, and the energy consumption of multiple water pumps of the same model operating in parallel is optimized.

[0051] Although the present invention has been disclosed as above in terms of preferred embodiments, they are not intended to limit the present invention. Anyone skilled in the art can make various changes or modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection defined by the claims of this application.

Claims

1. An energy-saving control method for an air-conditioning unit, which optimizes the parallel water pumps of the air-conditioning system; characterized in that: The following steps are involved: Step 1: Data processing; obtaining historical data and rated parameters of each parallel water pump of the air conditioning system; the historical data includes the water pump operating frequency F, actual power P a The rated parameters of the water pump include the rated power P e , rated frequency F e ; Pre-process the historical data and store it; Step 2: Establish a water pump energy consumption estimation model; take the actual power P of a single water pump as a As the dependent variable, the independent variables are the pump operating frequency F and the pump rated power P e ; Substitute the data preprocessed in step 1 into the following formula: The actual value of c is determined by fitting. If c is missing, it is c = 2.8; In actual operation, multiple inverters are adjusted simultaneously with equal frequencies, and the total power Pt is as follows: P t =N*P a (2); In formula (2), N represents the number of air conditioners, which is greater than or equal to 1; Step 3: Based on the water pump energy consumption estimation model, the total power of a single water pump, two water pumps, and even N water pumps within the upper and lower limits of the operating frequency is calculated respectively, and the critical switching frequency of the water pumps in parallel is determined, thereby forming a water pump operation energy consumption library; the water pump energy consumption library includes the number of running water pumps, the corresponding operating frequency, and the corresponding total power; Step 4: During actual operation, the total power P t The lowest value is the goal. The water pump energy consumption database is traversed and queried to confirm the number of water pumps turned on and the set value of the water pump operating frequency. At the same time, the constraint condition of "number of chillers turned on ≤ number of pumps turned on < number of chillers turned on + 2" is satisfied.

2. The energy-saving control method of an air-conditioning unit according to claim 1, characterized in that: The critical switching frequency of the water pumps in parallel in step 3 is determined as follows: based on the water pump operation energy consumption library, when M water pumps are switched to M+1 pumps in parallel operation, the critical energy consumption of the M+1 water pump is the energy consumption of the M+1 pump at its lower limit frequency; then, the critical frequency of the M water pumps is calculated based on the energy consumption of the M+1 water pump at its lower limit frequency; M+1≤N.

3. The energy-saving control method of an air-conditioning unit according to claim 1, characterized in that: The confirmation of the number of pumps to be turned on and the setting value of the pump operating frequency in step 4 are determined based on the critical switching frequency range when the pumps are connected in parallel.

4. The energy-saving control method of an air-conditioning unit according to claim 1, characterized in that: It also includes updating of a water pump energy consumption estimation model; the water pump energy consumption estimation model is updated to update historical data at a preset frequency, and the updated data is brought into step one to obtain a water pump energy consumption estimation model corresponding to the latest data.

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