A group control method, medium and computer device of a water chilling unit

Abstract

The application discloses a group control method, medium and computer equipment of a water chilling unit, and the method comprises the following steps: calculating a building cold load measurement value according to the chilled water supply and return water temperature and the chilled water flow; calculating the standard deviation of the cold load; calculating the cumulative density function according to the building cold load measurement value and the standard deviation of the cold load; setting the probability opening threshold value and the probability closing threshold value based on the target orientation; and performing loading or unloading control on the current running water chilling unit according to the cumulative density function, the probability opening threshold value and the probability closing threshold value, so that the robustness of the water chilling unit group control strategy is improved, and the central air conditioning system is guided to operate more efficiently and energy-savingly.

Description

Technical Field

[0001] This invention relates to the field of chiller group control technology, and more specifically to a group control method, medium, and computer equipment for water chiller units. Background Technology

[0002] Currently, most central air conditioning group control strategies in my country use either cooling capacity control or current ratio control to regulate the number of chiller units that start and stop. However, engineering practice has shown that cooling capacity control is affected by measurement uncertainties caused by sensor errors, and current ratio control is affected by threshold uncertainties. In practice, this results in poor robustness of the control strategy and reduces the system energy savings brought about by the automatic control system.

[0003] Therefore, how to improve the robustness of chiller group control strategies and guide central air conditioning systems to operate more efficiently and energy-savingly is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] In view of this, the present invention provides a group control method, medium and computer equipment for chiller units, which improves the robustness of chiller group control strategy and guides central air conditioning systems to operate more efficiently and energy-savingly.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention discloses a group control method for a chiller unit, comprising:

[0007] Calculate the building cooling load Q based on the chilled water supply and return temperatures and chilled water flow rate. meas ;

[0008] Calculate the standard deviation σ of cooling load Q ;

[0009] Based on the building cooling load measurement value Q meas and the standard deviation of cooling load σ Q Calculate the cumulative density function r z ;

[0010] A probability-based threshold γ is set based on a goal-oriented approach. on and probability threshold γ off ;

[0011] According to the cumulative density function r z , probability opening threshold γ on and probability threshold γ off To control the loading or unloading of the currently operating chiller unit.

[0012] Preferably, the standard deviation σ of the cooling load Q The specific calculation formula is as follows:

[0013]

[0014]

[0015] In the formula, C w Specific heat capacity of chilled water, kJ / (kg·K); m p，meas The mass flow rate of chilled water is measured in kg / s; Δ T，meas The measured temperature difference between chilled water supply and return water is in °C; σ m σ represents the standard deviation of chilled water mass flow rate. T For the temperature difference between chilled water supply and return water, σ T,rtn σ represents the return water temperature. T,sup This represents the standard deviation of the water supply temperature.

[0016] Preferably, the cumulative density function r z The specific calculation formula is as follows:

[0017]

[0018]

[0019] X z =QQ chiller,on

[0020] In the formula, Q represents the actual cooling load of the building, in kW; Q meas The measured value of building cooling load is kW; Q chiller The refrigeration capacity of the refrigeration unit is measured in kW; Q chiller，on The threshold for starting the chiller is kW; z represents the number of chillers currently in operation.

[0021] Preferably, a probability opening threshold γ is set based on target guidance. on and probability threshold γ off Specifically:

[0022] When maintenance is the primary concern: γ on =γ off =0.8;

[0023] When energy consumption is the primary consideration: γ on =0.8, γ off =0.3;

[0024] When comfort is the primary concern: γ on =0.3, γ off =0.8.

[0025] Preferably, based on the cumulative density function r z , probability opening threshold γ on and probability threshold γ offThe loading or unloading control of the currently operating chiller unit is determined based on the following principles:

[0026] S1: Determine whether r is satisfied simultaneously. z >γ on &t>t on PELA > PELA on &t>t on If the condition is met, one additional chiller unit will be started; otherwise, execute S2.

[0027] S2: Determine whether r is satisfied simultaneously. z <γ off &t>t off PELA < PELA off &t>t off If the conditions are met, one chiller unit will be shut down; otherwise, the status quo will be maintained.

[0028] Where PELA represents the full-load current percentage of the chiller unit, and t represents the duration of the chiller unit's operation. on Indicates the boot time limit, t off Indicates a shutdown time limit, PELA on This is the chiller unit start-up threshold correction value, PELA off This is the correction value for the shutdown threshold of the chiller unit.

[0029] Preferably, the chiller unit start-up threshold correction value PFLA on and chiller unit shutdown threshold correction value PFLA off The calculation formula is:

[0030]

[0031]

[0032] In the formula, α represents the maximum threshold of COP error. The start-up threshold is for a current ratio-based control strategy. PELA provides the shutdown threshold for a current ratio-based control strategy. on This is the chiller unit start-up threshold correction value, PELA off This is the correction value for the shutdown threshold of the chiller unit.

[0033] In a second aspect, the present invention discloses a computer device, comprising: a memory and a processor, wherein the memory stores a computer program executable on the processor, and when the processor executes the computer program, it implements the steps of the above-described method.

[0034] Thirdly, the present invention discloses a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the above-described method.

[0035] As can be seen from the above technical solutions, compared with the prior art, the present invention discloses a group control method, medium and computer equipment for a chiller unit. The optimized control strategy uses different cooling capacity indicators. When there are significant uncertainties such as sensor error and control threshold, the proposed strategy also has good robustness. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0037] Figure 1 The attached figure is a schematic diagram of a group control method for a chiller unit provided by the present invention.

[0038] Figure 2 The attached figure is a schematic diagram of the loading or unloading control strategy provided by the present invention. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] This invention discloses a group control method for chiller units, such as... Figure 1 As shown, it includes:

[0041] Calculate the building cooling load Q based on the chilled water supply and return temperatures and chilled water flow rate. meas ;

[0042] Calculate the standard deviation σ of cooling load Q ;

[0043] Based on the building cooling load measurement value Q meas and the standard deviation of cooling load σ Q Calculate the cumulative density function r z ;

[0044] A probability-based threshold γ is set based on a goal-oriented approach. onand probability threshold γ off ;

[0045] According to the cumulative density function r z , probability opening threshold γ on and probability threshold γ off To control the loading or unloading of the currently operating chiller unit.

[0046] Among them, the standard deviation of cooling load σ Q The specific calculation formula is as follows:

[0047]

[0048]

[0049] In the formula, C w Specific heat capacity of chilled water; m p，meas This is the measured mass flow rate of chilled water; Δ T，meas σ represents the measured temperature difference between the chilled water supply and return water. m σ represents the standard deviation of mass flow rate. T For the temperature difference between chilled water supply and return water, σ T,rtn σ represents the return water temperature. T,sup This represents the standard deviation of the water supply temperature.

[0050] Cumulative density function r z The specific calculation formula is as follows:

[0051]

[0052]

[0053] X z =QQ chiller,on

[0054] In the formula, Q represents the actual cooling load of the building; Q meas Q represents the measured value of the building's cooling load. chiller Q is the measured value of the refrigeration capacity of the refrigeration system. chiller，on The threshold for starting the chiller; z represents the number of chillers currently in operation.

[0055] In this embodiment, a probability opening threshold γ is set based on target guidance. on and probability threshold γ off Specifically:

[0056] When maintenance is the primary concern: γ on =γ off =0.8;

[0057] When energy consumption is the primary consideration: γ on =0.8, γ off =0.3;

[0058] When comfort is the primary concern: γ on =0.3, γ off =0.8.

[0059] In this embodiment, as Figure 2 As shown, according to the cumulative density function r z , probability opening threshold γ on and probability threshold γ off The loading or unloading control of the currently operating chiller unit is determined based on the following principles:

[0060] S1: Determine whether r is satisfied simultaneously. z >γ on &t>t on PELA > PELA on &t>t on If the condition is met, one additional chiller unit will be started; otherwise, execute S2.

[0061] S2: Determine whether r is satisfied simultaneously. z <γ off &t>t off PELA < PELA off &t>t off If the conditions are met, one chiller unit will be shut down; otherwise, the status quo will be maintained.

[0062] Where PELA represents the full-load current percentage of the chiller unit, and t represents the duration of the chiller unit's operation. on This indicates a time limit for booting up.

[0063] In this embodiment, the chiller unit start-up threshold correction value PFLA on and chiller unit shutdown threshold correction value PFLA off The calculation formula is:

[0064]

[0065]

[0066] In the formula, α represents the maximum threshold of COP error, defined by the COP curve, with a default value of 5%. The start-up threshold is for a current ratio-based control strategy. PELA provides the shutdown threshold for a current ratio-based control strategy. on This is the chiller unit start-up threshold correction value, PELA off This is the correction value for the shutdown threshold of the chiller unit.

[0067] In current ratio-based control strategies, using This can easily lead to delays in start-stop actions, therefore PFLA is used. on As a supplementary standard, This setting can reduce the delay caused by COP changes when switching the number of chillers.

[0068] This embodiment provides a computer device, including: a memory and a processor. The memory stores a computer program that can run on the processor. When the processor executes the computer program, it implements the steps of a group control method for a chiller unit.

[0069] This embodiment provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of a group control method for a chiller unit.

[0070] Those skilled in the art will understand that all or part of the steps of the above method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When the program is executed, it performs the steps of the above method embodiments. The aforementioned storage medium includes various media capable of storing program code, such as mobile storage devices, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0071] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0072] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A group control method for a chiller unit, characterized in that, include: Calculate the building cooling load measurement based on the chilled water supply and return temperatures and chilled water flow rate. ; Calculate the standard deviation of cooling load ; Based on building cooling load measurements and the standard deviation of cooling load Calculate the cumulative density function ; Setting a probability-based threshold based on goal orientation. and probability threshold ; According to the cumulative density function Probability Open Threshold and probability threshold To control the loading or unloading of the currently operating chiller units; Standard deviation of cooling load The specific calculation formula is as follows: In the formula, C w Specific heat capacity of chilled water; m p，meas This is the measured mass flow rate of chilled water; Δ T，meas This refers to the measured temperature difference between the chilled water supply and return water. For the standard deviation of chilled water mass flow rate, To address the temperature difference between the chilled water supply and return water, The return water temperature, This represents the standard deviation of the water supply temperature. Cumulative density function The specific calculation formula is as follows: In the formula, Q represents the actual cooling load of the building; Q meas Q represents the measured value of the building's cooling load. chiller Q is the measured value of the refrigeration capacity of the refrigeration system. chiller，on This represents the threshold for starting the chiller; z indicates the number of chillers currently in operation. Setting a probability-based threshold based on goal orientation. and probability threshold Specifically: When maintenance is the primary concern: = =0.8; When energy consumption is the primary consideration: =0.8, =0.3; When comfort is the primary consideration: =0.3, =0.

8.

2. The group control method for a chiller unit according to claim 1, characterized in that, According to the cumulative density function Probability Open Threshold and probability threshold The loading or unloading control of the currently operating chiller unit is determined based on the following principles: S1: Determine if both conditions are met simultaneously. , If the condition is met, one additional chiller unit will be started; otherwise, execute S2. S2: Determine whether both conditions are met simultaneously. , If the conditions are met, one chiller unit will be shut down; otherwise, the status quo will be maintained. Where PELA represents the full-load current percentage of the chiller unit, and t represents the duration of the chiller unit's operation. This indicates a time limit for booting up. Indicates a shutdown time limit, PELA on This is the chiller unit start-up threshold correction value, PELA off This is the correction value for the shutdown threshold of the chiller unit.

3. The group control method for a chiller unit according to claim 2, characterized in that, Chiller start-up threshold correction value and chiller unit shutdown threshold correction value PFLA off The calculation formula is: In the formula, This represents the maximum threshold for COP error. The start-up threshold is for a current ratio-based control strategy. This is the shutdown threshold for a current ratio-based control strategy.

4. A computer device, characterized in that, include: A memory and a processor, wherein the memory stores a computer program executable on the processor, and the processor, when executing the computer program, implements the steps of the method according to any one of claims 1 to 3.

5. A computer-readable storage medium, characterized in that, The storage medium stores a computer program that, when executed by a processor, implements the steps of the method according to any one of claims 1 to 3.

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