JP2007085601A - Operation method of refrigerating machine and equipment comprising the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve accuracy of power saving technology as operation technology of a plurality of refrigerating machines in air conditioning equipment. <P>SOLUTION: An approximate expression modeling relationship between refrigerating capacity and electric power consumption of each of the plurality of refrigerating machines corresponding to characteristics of each portion, is determined, centers of gravity of operation result data of the plurality of refrigerating machines are compared, the approximate expression is corrected on the basis of changed portion of a relative value, the total electric power consumption of the plurality of refrigerating machines are calculated on the basis of the corrected approximate expression, the refrigerating capacity of each refrigerating machine in a case of reducing the calculated total electric power consumption is determined, and an operating state of each refrigerating machine is controlled on the basis of the determined refrigerating capacity. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to equipment for refrigeration, cooling or cooling, and in particular, to a technique for operating a plurality of refrigerators used therefor.

Conventionally, as a facility using a refrigerator, there are a freezer / refrigerator facility and an air conditioner. In these facilities, the refrigerator is driven by electric power supplied from a power converter such as an inverter, and supplies a fluid having a predetermined temperature such as water to a load section in the facility. Therefore, energy saving of these facilities is generally achieved by reducing the driving power of the refrigerator.
As a conventional technique related to reduction of driving power of a refrigerator, a technique described in the literature includes, for example, a technique described in Japanese Patent Application Laid-Open No. 9-145176 (Patent Document 1). In this publication, in a system using a plurality of refrigeration apparatuses, in order to maximize the energy consumption efficiency of the entire system, when the entire system becomes a partial load, the energy consumption efficiency of the entire system is maximized. The technique which calculates the point to perform and operates each refrigeration apparatus with this maximum point is described.

JP-A-9-145176

In order to save energy, including conventional technology, some kind of equipment modeling is required. In the above prior art, the partial load characteristics of the refrigerator are modeled. However, since they are incorporated at the time of system development through manual analysis and the like, it is difficult to review the model after completion of the system. The modeling method includes the use of catalog values and the use of operation result data, and the accuracy of the energy saving effect obtained varies depending on the modeling method. When the catalog value is used, since it is an ideal value characteristic, it is often different from the operation characteristic incorporated in the actual air conditioning equipment. For example, in general, during operation in winter, since the driving state exhibits a capacity exceeding the rating, the characteristics are considerably different from the catalog values. In addition, when the operation result data is used, the characteristics of the refrigerator change due to the influence of the cooling water that comes into contact with the outside air, so that a difference from the initial model occurs. In addition, measurement values may not be obtained for all necessary data. In such a case, data that cannot be measured is obtained by calculation using constants such as fixed values. Data obtained based on such calculation usually includes an error and often does not have an accurate value.
The problem of the present invention is that, in view of the state of the prior art described above, in the operation technology of a plurality of refrigerators (refrigeration devices) used for refrigeration, cooling, or cooling equipment, each refrigerator has characteristics of each refrigerator, It is to operate in a control state corresponding to ambient conditions such as outside air conditions, and to reduce the power consumption of a plurality of refrigerators as a whole.
An object of the present invention is to solve such problems and provide an operation technique capable of further reducing power consumption in the operation technique of the refrigerator (refrigeration apparatus).

  In order to solve the above problems, in the present invention, as an operation technique of a plurality of refrigerators in an air conditioning facility, an approximation obtained by modeling the relationship between the refrigeration capacity and power consumption of each of the plurality of refrigerators according to the characteristics of each part. Obtaining the formula, obtaining the overall power consumption of the plurality of refrigerators based on the approximate expression, setting the freezing capacity of each refrigerator when the obtained overall power consumption is reduced, and the set freezing capacity Thus, the operation state of each refrigerator is controlled. The above model, for example, focuses on the operation result data in units of one month in each of a plurality of refrigerators, is extracted from the operation result data under the same condition of the cooling water inlet temperature, and is used as a reference data (hereinafter referred to as the center of gravity). ) Is compared, and the calculated center of gravity is compared with the center of gravity of the previous month under the same extraction condition, and the approximate expression is corrected with the change ratio using the difference as a relative value. Further, the above approximation is applied to the approximate expression of the cooling water inlet temperature other than the extraction condition for obtaining the center of gravity, and the approximate expression is reviewed. The revision of the model is automatically repeated, for example, in units of one month (24 points × 30 or 31 on the hour). The review cycle can be handled according to the amount of change in characteristics, such as whether the start date is shifted daily, shifting every day, shifting every week, or monthly.

  According to the present invention, each refrigerator can be operated in a controlled state corresponding to the actual conditions such as ambient conditions such as the characteristics of each refrigerator and the outside air temperature, and the power consumption of the entire plurality of refrigerators under the operating conditions. Can be reduced.

Embodiments of the present invention will be described below with reference to the drawings.
1-5 is explanatory drawing of the Example of this invention. FIG. 1 is a configuration diagram of a refrigeration facility as an embodiment of the present invention, FIG. 2 is an explanatory diagram of an operation procedure of a plurality of refrigerators and a plurality of cold water secondary pumps in the facility of FIG. 1, and FIG. FIG. 4 is an explanatory view of a procedure for correcting an equipment characteristic model used for optimal calculation of a plurality of refrigerators in the facility of FIG. 1, and FIG. 4 is an equipment characteristic model used for optimal calculation of a plurality of cold water secondary pumps in the equipment of FIG. FIG. 5 is a diagram illustrating an example of device characteristic model correction of a plurality of refrigerators in the facility of FIG. 1, and FIG. 6 is a device characteristic of a cold water secondary pump in the refrigeration facility of FIG. It is a figure which shows an example of model correction.

In FIG. 1, 100 is a refrigeration facility, 1 is a refrigerator unit comprising a plurality of refrigerators R ₁ ,..., R _n , 2 is an operation control unit that controls the operation of the refrigerator unit 1, The load section 4 is a cold water tank, 5 is a cold water secondary pump section comprising a plurality of cold water secondary pumps P ₁ ,..., _Pn that pumps cold water from the cold water tank 4, and 6 is an adjustment of the flow rate of the cold water. A cold water header to be performed, 7 is a phase adjuster, 11 is a first temperature / flow rate monitoring point, 12 is a second temperature / flow rate monitoring point, 13 is a header pressure monitoring point for monitoring the pressure of the cold water in the cold water header 6, T ₁ is the temperature of the chilled water at the first temperature / flow rate monitoring point 11, Q ₁ is the amount of chilled water delivered at the first temperature / flow rate monitoring point 11, and T ₂ is the second temperature / flow rate monitoring point 12. The cold water return temperature, H, is the header pressure at the header pressure monitoring point 13. Refrigerator unit 1, each refrigerator R _1, ..., R _n is, a refrigerant by the driving motor (not shown) together with the circulating each refrigerator at a predetermined flow rate and speed, the water of the cold water tank 4 Then, the refrigerant is cooled by the refrigerant while being circulated with the freezing tank 4. The phase adjuster 7 is composed of, for example, an air conditioner. In the above configuration, each of the refrigerators R ₁ ,..., R _n of the refrigerator unit 1 is controlled by the operation control unit 2, and is subjected to a predetermined condition, that is, a predetermined refrigeration capacity, a predetermined drive motor input, and a predetermined power consumption. And so on. Each of the refrigerators R ₁ ,..., R _n of the refrigerator unit 1 operated under the operating conditions pumps a part of the water on the high-temperature tank side in the cold water tank 4 and converts the pumped water into a freezing capacity by the refrigerant. Correspondingly, it is cooled and returned to the cold / warm tank side in the cold water tank 4 again. This is repeated. Each of the chilled water secondary pumps P ₁ ,..., P _n of the chilled water secondary pump unit 5 is controlled by the operation control unit 2, and the header pressure at the header pressure monitoring point 13 of the chilled water header 6 is adjusted under a certain condition. Each of the chilled water secondary pumps P ₁ ,..., P _n in accordance with the flow rate (water supply amount) at the temperature / flow rate monitoring point 11 of ₁ pumps a part of the water on the low temperature tank side in the chilled water tank 4, Water is fed to the header 6.

The cold water in the cold water header 6 is supplied to the load unit 3 through the first temperature / flow rate monitoring point 11. The header pressure monitoring point 13 detects the pressure in the header. At the first temperature / flow rate monitoring point 11, the temperature T _{1 of the} cold water and the amount Q _{1 of} water are detected. In the load unit 3, the cold water is supplied to the phase adjuster 7. The phase adjuster 7 cools the sucked air in accordance with the state of the cold water, and discharges it as a freezing air to a predetermined target space. The chilled water whose temperature has risen due to heat from the air in the phase adjuster 7 is returned to the chilled water tank 4 again from the load section 3 via the second temperature / flow rate monitoring point 12. At the second temperature / flow rate monitoring point 12, the temperature T ₂ (T ₂ > T ₁ ) of the cold water is detected. Both the information on the temperature and flow rate detection result at the first temperature / flow rate monitoring point 11, the information on the temperature detection result at the second temperature / flow rate monitoring point 12, and the header pressure at the header pressure monitoring point 13 are both operated. 2 is input. Based on this information, the operation control unit 2 controls the refrigerator unit 1 so that each of the refrigerators R ₁ ,..., R _n of the refrigerator unit 1 has a predetermined refrigeration capacity. For example, the load unit 3 is a partial load, if may be less coolant flow rate, the refrigerator R _1, ..., per that of all or part of R _n, control so as to reduce the refrigeration capacity To do. Further, the operation control unit 2, the chilled water secondary pump P _1, ..., a variable operation frequency of P _n, and controls to decrease the a and operation frequency smaller number of operating. The control of the refrigerator unit 1 by the operation control unit 2 is basically made to achieve a predetermined refrigeration capacity with as little power consumption as possible. For this purpose, the operation control unit 2 controls the refrigerator unit 1 as follows. That is, the operation control unit 2 sets a predetermined plurality of combinations of the refrigerators R ₁ ,..., R _n to be operated, and sets the target refrigeration capacity of the load unit to each of the combinations. And distributing to each refrigerator based on the rated refrigeration capacity of each of the operated refrigerators, substituting the allocated refrigeration capacity into a modeled approximate expression indicating the relationship between the refrigeration capacity and power consumption, and The power consumption of each refrigerator is calculated for all the combinations of the refrigerators, and the total of the calculated power consumptions is calculated for each combination, and the total value is the minimum or lower than the other combination A combination to be a value is selected and set, and a plurality of refrigerators of the set combination are controlled to operate at a refrigeration capacity value equal to or close to the above-mentioned distributed refrigeration capacity.

Furthermore, the control of the cold water secondary pump unit 5 by the operation control unit 2 is achieved with as little power consumption as possible in accordance with a predetermined water supply amount. For this purpose, the operation control unit 2 controls the cold water secondary pump unit 5 as follows. That is, the operation control unit 2, the chilled water secondary pump P ₁ of the same _rating, ..., the P _n, when the plant is operated n stand from one, and indexing the pump speed commensurate with the water supply amount per one, its From the power consumption per unit, the total power consumption during the operation of one to n units is compared, and control is performed so that the number of operating units with the lowest power consumption and the pump rotation speed at that time are operated. The pump rotational speed corresponding to the amount of water delivered by each chilled water secondary pump uses an approximate expression that models equipment characteristics (QH characteristics) when each chilled water secondary pump is operated at 50 Hz.

FIG. 2 is an explanatory diagram of an operation procedure of a plurality of refrigerators and a plurality of cold water secondary pumps in the facility of FIG.
In FIG.
(1) First, the operation control unit 2 starts control operations of the refrigerator unit 1 and the cold water secondary pump unit 5 (step S201).
(2) Model data obtained by formulating the partial load characteristics of the refrigerators having different specifications and the equipment characteristics of the cold water secondary pump having the same specifications as approximate expressions are stored in advance. The operation control unit 2 reads these data and makes them resident in a memory or the like in order to use them for calculation (step S202).
(3) The optimal calculation of the refrigerator is the most energy-saving (low power consumption) operation pattern when the refrigeration load is allocated to the operation combination of multiple refrigerators as the refrigeration load required for the current demand on the load side. Calculated using a refrigerator model. Moreover, in order to cover the current water supply in the optimal calculation of the cold water secondary pump, the number of pump rotations is calculated for each unit of operation using the model, and the power consumption is calculated from the number of rotations. The number of chilled water secondary pumps that are derived and have the smallest total power consumption is determined (step S203).
(4) The optimal calculation is executed at a fixed cycle (for example, a cycle of 5 minutes), and the calculation results of the refrigerator and the chilled water secondary pump are displayed as guidance to inform the operator (step S204).
(5) Measurement data of various facilities required for optimal calculation and data monitoring the equipment status are saved to the magnetic disk etc. in hourly units, making it possible to separately refer to the trend display etc. (Step S205).

FIG. 3 is an explanatory diagram of a procedure for correcting an equipment characteristic model used for optimal calculation of a plurality of refrigerators in the facility of FIG.
The control of the following procedure is performed paying attention to one refrigerator, and the same control is performed for all the refrigerators operating in the same procedure. In addition, the following procedure is periodically reviewed, for example, by shifting the start date one day at a time, shifting the start date for one week, or performing it in units of one month, for example, with data of one month span.

(1) The partial load characteristic data (production heat quantity and power consumption of the refrigerator) is classified according to the cooling water inlet temperature when the refrigerator is operated from the operation results for one month of the refrigerator. Extracted and stored (step S302). The data for one month covers the data amount of 744 points for 24 hours × 31 days, with the data on the hour as one point.
(2) It is determined whether the score (number of samples) of the data extracted and classified for each cooling water inlet temperature is a score sufficient for evaluation by comparing with the reliability coefficient and the value in the number table of the standard normal distribution (step S303). ). A sample with a sufficient number of samples worthy of evaluation is considered as the next processing target.
(3) The center of gravity is obtained from the data classified and extracted for each cooling water inlet temperature. Further, a standard deviation obtained by comparing the center of gravity and one point of each data is obtained. Data that is far from the standard deviation of 3σ (standard deviation × 3) or more is excluded from the data to be evaluated as bad data and used as a rejection test. The center of gravity is obtained again using the data after the rejection test, and this center of gravity is made positive (step S304).
(4) The reliability obtained by checking the data obtained by the above (3) in which the center of gravity is biased or uniformly distributed is checked. The reliability is confirmed by the bootstrap method (reconstruction extraction from the original database, creation of a database necessary for estimating the distribution of parameters and statistics to be evaluated, and using the estimated distribution, (Method of verifying stability) For example, 2/3 of the sample is used as a subset, the center of gravity is obtained, the standard deviation from the center of gravity is obtained using the remaining 1/3 subset, and the center of gravity is similarly obtained from the subset selected again at random. And the standard deviation is repeated several times. The reliability of the center of gravity subjected to the rejection test in (3) above is judged by the magnitude of the standard deviation obtained repeatedly. Only when the center of gravity obtained by the rejection test in (3) is reliable, it is stored and left (step S305).
(5) The processes of (3) and (4) are repeated for each cooling water inlet temperature data (step S306).
(6) Select the center of gravity with high reliability from the current month and last month. If there is a center of gravity of the same cooling water inlet temperature in the selected one, the amount of change in the partial load characteristic data is obtained from the compared difference using the center of gravity (step S307). This amount of change is a value to be corrected by reflecting it in the approximate expression.
(7) The amount of change obtained in (6) above is also reflected and corrected in the approximate expression of each cooling water inlet temperature of the refrigerator (step S308).

FIG. 4 is an explanatory diagram of a procedure for correcting a device characteristic model used for optimal calculation of a plurality of cold water secondary pumps in the facility of FIG. Unlike chillers, multiple chilled water secondary pumps are all composed of motors with the same rating and specifications, so Q-H characteristic data, which is the operational performance of all pumps, is handled together.
In FIG.
(1) The QH characteristic data is classified and extracted for each pump operating frequency from the operation results for one month of all the secondary pumps (step S402). The number of data points is 744 points (on the hour x 24:00 x 31 days).
(2) The data extracted for each frequency in the above (1) is further subdivided and stored for each header pressure at that time (step S403).
(3) It is determined whether or not the number of data points subdivided in (2) above is sufficient for evaluation by comparing the reliability coefficient with the values in the number table of the standard normal distribution (step S404). A sample with a sufficient number of samples worthy of evaluation is considered as the next processing target.
(4) Find the center of gravity from the subdivided data. Further, a standard deviation obtained by comparing the center of gravity and one point of each data is obtained. Data that is far from the standard deviation of 3σ (standard deviation × 3) or more is excluded from the data to be evaluated as bad data and used as a rejection test. The center of gravity is obtained again using the data after the rejection test, and this center of gravity is made positive (step S405).
(5) The center of gravity and the standard deviation are obtained by the bootstrap method, the reliability of the center of gravity after the rejection test is confirmed, and it is determined whether or not the center of gravity obtained by the rejection test can be used (step S406).
(6) The above (4) and (5) are carried out for other header pressure data of the frequency, and the calculation is repeated for the extracted data for each header pressure of the other frequency (step) S407).
(7) The most reliable centroid is selected from the centroid for each header pressure of each frequency for this month. The flow rate and the center of gravity when the 50 Hz characteristic of the pump is slid to the same frequency and head are compared, the amount of change is obtained from the difference, and this is reflected in the approximate expression of the 50 Hz characteristic of the pump and corrected (step S408).

  FIG. 5 is a diagram showing an example of correction of the device characteristic model in the plurality of refrigerators in the facility of FIG. This figure shows a case where the center of gravity of partial load characteristic data for two months is compared, and the approximate expression of the model is corrected using the difference as a change amount. In the figure, A is a model characteristic at a certain cooling water inlet temperature, and B is a characteristic when correction is performed to reflect the amount of change.

  FIG. 6 is a diagram illustrating an example of device characteristic model correction of the cold water secondary pump in the facility of FIG. The QH characteristic of the pump shows only the model characteristic at 50 Hz (characteristic C). This characteristic is slid to the same frequency at which the center of gravity is calculated (characteristic E), and the flow rate is obtained from the head showing the same header pressure. The flow rate of the center of gravity is compared with the flow rate of the characteristic, and the pump model is corrected using the difference as the amount of change (correction characteristic D).

In the above-described embodiment, it has been described that the standard deviation is 3σ (standard deviation × 3) or more when the data to be evaluated is excluded. However, in the practice of the present invention, the standard deviation is not limited to 3σ but may be σ, 2σ, or the like, and may be appropriately selected.
In the above embodiment, the bootstrap method is used to obtain the center of gravity and the standard deviation. However, another method may be used.

It is an example of composition of refrigeration equipment as an example of the present invention. It is explanatory drawing of the operation | movement operation procedure of the some refrigerator in the installation of FIG. 1, and a some cold water secondary pump. It is explanatory drawing of the correction | amendment procedure of the apparatus characteristic model used for the optimal calculation of the some refrigerator in the installation of FIG. It is explanatory drawing of the correction | amendment procedure of the apparatus characteristic model used for the optimal calculation of the some cold water secondary pump in the installation of FIG. It is a figure which shows an example of the apparatus characteristic model correction | amendment of the some refrigerator in the installation of FIG. It is a figure which shows an example of the apparatus characteristic model correction | amendment of the cold water secondary pump in the installation of FIG.

Explanation of symbols

1 ... Refrigerator part,
2 ... Operation control part,
3 ... load section,
4 ... cold water tank,
5 ... Cold water secondary pump part,
6 ... Cold water header,
7 ... Phase adjuster,
11: First temperature / flow rate monitoring point,
12 ... Second temperature / flow rate monitoring point,
13 ... Header pressure monitoring point,
100: Equipment for refrigerators.

Claims (6)

A method of operating a plurality of refrigerators in an air conditioning facility,
A first step of obtaining an approximate expression in which the relationship between the refrigeration capacity and the power consumption of each of the plurality of refrigerators is modeled corresponding to the characteristics of each part;
A second step of determining the overall power consumption of the plurality of refrigerators based on the approximate expression;
A third step of setting the refrigeration capacity of each refrigerator when reducing the total power consumption obtained above;
A fourth step of controlling the operating state of each refrigerator with the set refrigeration capacity;
And operating each of the above refrigerators.   The operation method of the refrigerator according to claim 1, wherein in the first step, the gravity centers of the operation results data of the plurality of refrigerators are compared, and the approximate expression is corrected based on a change in relative value.   The operating method of the refrigerator according to claim 1, wherein in the first step, the approximate expression is corrected with a change in the operation result data of the plurality of refrigerators as a characteristic change.   The method of operating a refrigerator according to claim 1, wherein, in the third step, the refrigerating capacity of each refrigerator when the overall power consumption of the plurality of refrigerators is minimized is set.   The said 1st step WHEREIN: The said modeled approximate expression is regularly reviewed, The said 2nd step calculates | requires the whole power consumption of several refrigerator with the said approximated formula. How to operate the refrigerator. A facility that uses a refrigerator to perform freezing, cooling or cooling,
A plurality of refrigerators for cooling the fluid for freezing, cooling or cooling;
Obtain an approximate expression that models the relationship between the refrigeration capacity and power consumption of each of the multiple refrigerators according to the characteristics of each part, and compare the centroids of the operation data of the multiple refrigerators to change the relative value. Correcting the approximate expression based on the calculation, calculating the overall power consumption of the plurality of refrigerators based on the corrected approximate expression, setting the refrigerating capacity of each refrigerator when reducing the calculated overall power consumption, An operation control unit for controlling the operation state of each refrigerator with the set refrigeration capacity;
A facility characterized by comprising.

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