JP5969907B2 - Driving efficiency estimation device and program - Google Patents

Description

  The present invention relates to a compressor control technique, and more particularly to an operation efficiency estimation technique for individually estimating compressor operation efficiency for a plurality of compressors operated in parallel.

  In facilities such as factories, a compressed air supply system using a plurality of compressors is provided, and by operating these compressors in parallel, the air (or mixed gas such as refrigerant) is compressed, and the obtained compressed air is used. Once collected in the tank, it is distributed and supplied from the header to each load of the facility.

  The power energy consumed by such a compressed air supply system occupies a relatively large proportion of the power energy consumed by the entire facility. For this reason, when energy saving and CO2 saving of equipment are considered, energy saving and CO2 saving in the compressed air supply system, that is, improvement in operating efficiency in each compressor is required.

  The operating efficiency of the compressor is presented as technical data by the manufacturer. This operating efficiency is the best value obtained during rated operation when the compressor is operated stably for a certain time at the maximum discharge rate, that is, the rated efficiency. Or, even in a state where the discharge amount is lower than the maximum, it is the efficiency in a so-called steady state in which the discharge amount is operated for a certain period of time. Therefore, if the new compressor can be operated at almost the rated operation at all times or without causing a change in flow rate, such an optimum operation efficiency can be obtained.

  However, in the compressed air supply system, the amount of compressed air consumed varies depending on the operating condition on the load side, so the operating state of the compressor is adjusted to maintain the supplied compressed air amount and air pressure at appropriate values. There is a need. For this reason, in an actual situation where the operating state of the compressor changes, the efficiency presented by the manufacturer as the specification cannot be obtained. Therefore, it is necessary to grasp what operating efficiency each compressor is actually operating.

  Further, since the operating efficiency of the compressor is lowered not only by the operating state but also by the aging of the compressor, it is necessary to perform maintenance periodically. At this time, by performing maintenance from the compressor having the greatest decrease in operating efficiency, the operating efficiency of the entire compressed air supply system can be improved at an early stage. Therefore, it is important to grasp the operational efficiency of each compressor individually in real time.

  Further, in the compressed air supply system, the number control for efficiently operating the compressors is performed by starting / stopping each compressor according to the magnitude of the load measured by the supply pressure or flow rate of the compressed air. In this case, among the compressors, a method of selecting and starting the compressors in order from those having the highest operating efficiency is a basic concept of unit control based on energy saving and CO2 saving. Therefore, it is important to grasp the operation efficiency of each compressor individually.

  Conventionally, in such a compressed air supply system, a technique for managing the operation efficiency of each compressor has been proposed (see, for example, Patent Documents 1-3). According to these, in addition to the supply energy index collected for each compressor, such as the amount of power used in the compressor, the consumption efficiency index such as the flow rate data for the compressor is used to obtain the operating efficiency of each compressor. It has become.

JP 2011-248568 A JP 2012-068878 A JP 2001-191789 A

  In such a conventional technique, the operating efficiency of each compressor is obtained by using a consumption energy index such as flow rate data in each compressor in addition to a supply energy index such as power consumption in each compressor. For this reason, equipment such as a flow meter for measuring the flow rate of the compressed air output from the compressor is required for each compressor. Therefore, according to the prior art, in order to obtain the compressor operating efficiency, it is necessary to add equipment to each compressor, and not only equipment costs but also management costs are required, and the compressor is temporarily stopped for equipment addition. There was a problem that it was necessary to do.

  The present invention is for solving such problems, and it is possible to easily estimate the operation efficiency of the compressor while continuously operating without requiring the addition of equipment for each compressor. The purpose is to provide technology.

In order to achieve such an object, the operation efficiency estimating apparatus according to the present invention is configured for n (n is an integer of 2 or more) compressors Ci (i = 1 to n) in parallel operation. An operating efficiency estimation device for individually estimating the operating efficiency of a compressor,
At each time t, a power usage Wti indicating individual power used per unit time in each compressor Ci and an overall flow rate Qt indicating the flow rate of the entire compressed air supplied from the compressor Ci are collected, A data collection unit that stores the power consumption Wti and the total flow rate Qt in the storage unit as a data set of the time t, and the total flow rate Qt is reduced from the data set stored in the storage unit. M (= n × 2) are selected as target data sets Dt, and the flow rate change rate λt for the total flow rate Qt, the total flow rate Qt, and the power usage obtained for each target data set Dt are selected. Operating efficiency characteristic coefficients ai and bi indicating the intercept and slope of a linear function approximating the relationship between the amount Wti, the flow rate change rate for each compressor Ci, and the operating efficiency Are used to generate m calculation formulas relating to the total flow rate Qt shown in the above formula for each target data set Dt, and solving these flow calculation formulas as simultaneous equations, the operational efficiency characteristic coefficients ai and bi By multiplying the flow rate change rate λx at an arbitrary time x by the operation efficiency characteristic coefficient bi of the compressor Ci and adding the operation efficiency characteristic coefficient ai of the compressor Ci. and an operation efficiency calculation unit for calculating the operation efficiency Uxi of the compressor Ci at x.

  Also, in one configuration example of the operation efficiency estimation apparatus according to the present invention, the coefficient calculation unit calculates a condition number κ (A) (Condition Number) related to the coefficient matrix A of the simultaneous equations, and the condition number κ When (A) and the threshold value κth are compared to determine whether sufficient solution accuracy can be obtained from the target data set Dt, and the condition number κ (A) is greater than the threshold value κth In this case, part of the data sets constituting the target data set Dt is repeatedly exchanged until the condition number κ (A) becomes equal to or less than the threshold value κth.

  Moreover, the program concerning this invention is a program for functioning a computer as each part of the driving | running efficiency estimation apparatus mentioned above.

  According to the present invention, the operating efficiency of each compressor is reduced to the power consumption of each compressor obtained with a power meter installed in advance in a general compressed air supply system and the total flow rate obtained with the flow meter. Calculated based on For this reason, it becomes possible to estimate the operating efficiency of each compressor easily without requiring addition of equipment such as a flow meter for measuring flow rate data in the compressor, for example.

  In addition, since the operation efficiency can be estimated for each compressor, the administrator can easily grasp what operation efficiency each compressor is actually operating. Thereby, the operation order in the unit control can be reviewed, and energy saving and CO2 saving can be realized. In addition, it is possible to plan whether or not maintenance is required for each compressor, and from which compressor to perform maintenance in order, and it is possible to provide extremely useful data for determining whether or not to replace a compressor.

It is a block diagram which shows the structure of a driving efficiency estimation apparatus. It is a graph which shows the operation efficiency characteristic depending on the flow rate change rate of an air flow rate. It is a structural example of a data set. It is a structural example of coefficient data. It is a flowchart which shows the coefficient calculation process in a driving efficiency estimation apparatus. It is a flowchart which shows the driving efficiency calculation process in a driving efficiency estimation apparatus. It is an example of an individual display screen of operational efficiency. It is an example of a list display screen of operational efficiency. It is a graph which shows simultaneous equations and its solution. It is a flowchart which shows the object data set production | generation process in a driving efficiency estimation apparatus.

[Principle of the Invention]
First, the principle of the present invention will be described.
In a compressed air supply system in which n (n is an integer of 2 or more) compressors C1 to Cn are operated in parallel, the operation efficiency of each of the compressors C1 to Cn is individually observed and analyzed by a conventional method. It was found that the operation efficiency tends to decrease in a specific time zone. Further, as a result of analyzing the relationship between the air flow rate and the operation efficiency in more detail, it was found that the operation efficiency was reduced during the time zone in which the air flow rate was decreasing.

FIG. 2 is a graph showing operating efficiency characteristics depending on the flow rate change rate of the air flow rate. Here, the horizontal axis represents the rate of change λ [%] of the air flow rate, and the vertical axis represents the operating efficiency Ui [m ³ / kWh] of the compressor Ci (i = 1 to n) consisting of the basic unit. . According to this graph, when the flow rate change rate λ is 0 or more, that is, when the air flow rate is the same or increased as compared with the immediately preceding time, the operation efficiency Ui of the compressor Ci is substantially constant, and the flow rate change rate. When the air flow rate is reduced compared to the negative side region where λ is less than 0, that is, immediately before the time, the operation efficiency Ui is reduced in accordance with the magnitude of the flow rate change rate λ. One of the causes is that when the air flow rate decreases, the main power generation source such as the motor of the compressor Ci rotates due to the inertia so far, so that the power decrease responds later than the flow rate decrease. It is done.

The present invention pays attention to the fact that among the operating efficiency characteristics depending on the flow rate change rate λ of the air flow rate in such a compressor Ci, the characteristics in the negative region where the flow rate change rate λ is smaller than 0 can be approximated by a linear function. Is. That is, when the flow rate change rate of the total flow rate Qt at time t is λt, and the intercept and slope of the linear function are ai and bi, respectively, the operating efficiency Uti of the compressor Ci at time t is expressed by the following equation (1). expressed.

In addition, it was observed that the operating efficiency characteristic coefficients ai and bi have unique values for the compressors C1 to Cn. Therefore, using this linear function, the individual flow rate Qti of the compressor Ci at time t is expressed by the following equation (2). When the total flow rate at time t is Qt, the total flow rate at time t-1 that is a unit time backward from time t is Qt-1, and the intercept and slope of the linear function are ai and bi, respectively, λt at t is expressed by the following equation (3).

Therefore, when the electric power consumption in the compressor Ci at time t is Wti, the entire flow rate Qt of the entire compressors C1 to Cn is expressed by the following equation (4).

Here, when there are n compressors Ci, there are n ai and bi, respectively. Therefore, if Equation (4) is prepared for m (= n × 2), by solving these as simultaneous equations, ai , Bi can be obtained.
Further, the overall flow rate Qt of the entire compressors C1 to Cn and the power consumption Wti of each compressor Ci can be easily measured at every time t in the general compressed air supply system 1 without adding a large facility. .

Therefore, the present invention acquires m target data sets Dt in which Qt is decreasing from the data sets of Qt and Wti measured at each time t, and uses these Dt to obtain equation (4). Are generated, and ai and bi are calculated by solving simultaneous equations composed of these flow rate calculation formulas.
Thereafter, λx obtained by substituting Qx and Qx−1 at an arbitrary time x into the equation (3) and ai and bi of the compressor Ci obtained previously are substituted into the equation (1). The operation efficiency Uxi of each compressor Ci at time x is obtained.

[First Embodiment]
Next, with reference to FIG. 1, the driving | running efficiency estimation apparatus 10 concerning the 1st Embodiment of this invention is demonstrated. FIG. 1 is a block diagram showing the configuration of the driving efficiency estimation device.

  The operation efficiency estimation device 10 is composed of an information processing device such as a controller, a server device, and a personal computer as a whole, and is collected from the compressed air supply system 1 in which a plurality of compressors C (C1 to Cn) are operated in parallel. Based on the electric power consumption Wti (an integer of i = 1 to n) relating to the compressors C1 to Cn and the overall flow rate Qt, the operation efficiency relating to the individual compressors C1 to Cn is estimated.

  In the compressed air supply system 1 shown in FIG. 1, compressed air obtained by operating the compressors C <b> 1 to Cn in parallel with the supplied power PW is once collected in the tank 3 via the pipe 2, and then the pipe 4 And, it is supplied to each load 6 such as a processing machine that consumes compressed air via the header 5. These compressors C are compressed by the compressor control unit 7 with a compressed air flow rate Qt measured at a time t by a flow meter 4A provided in the pipeline 4 or a pressure gauge 5A provided in the header 5. By controlling the number of units based on the air pressure Pt, operation / stop or load / unload is individually controlled to stably supply compressed air to the load 6.

[Operating efficiency estimation device]
Next, the configuration of the driving efficiency estimation device 10 will be described with reference to FIG.
The driving efficiency estimation device 10 includes a data collection unit 11, an operation input unit 12, a screen display unit 13, a storage unit 14, a coefficient calculation unit 15, and an operation efficiency calculation unit 16 as main functional units.

  The data collection unit 11 measures the individual electric power used per unit time at each time t measured by the wattmeter 8 (81-8n) provided for each compressor Ci (i = 1 to n). A function of collecting the electric power consumption Wti that is indicated, and an overall flow rate Qt that is measured by the flowmeter 4A provided in the pipeline 4 and that indicates the flow rate of the entire compressed air supplied from the compressor Ci, and these electric power consumptions It has a function of storing Wti and the entire flow rate Qt in the storage unit 14 as a data set 14A for the time t.

The operation input unit 12 includes an operation input device such as a keyboard and a mouse, and has a function of detecting and outputting an operator's operation.
The screen display unit 13 includes a screen display device such as an LCD, and has a function of displaying an operation screen for estimating driving efficiency and a data screen obtained by each functional unit.

The storage unit 14 includes a hard disk and a semiconductor memory, and has a function of storing various processing data and programs 14P used for processing in each functional unit.
The program 14P is a program for realizing each functional unit by being executed by a computer, and is read from an external device or a recording medium and stored in the storage unit 14 in advance.

Main processing data stored in the storage unit 14 includes a data set 14A and coefficient data 14B.
The data set 14 </ b> A is data composed of a set of the power usage amount Wti and the total flow rate Qt in each compressor Ci at each time t collected by the data collection unit 11.
FIG. 3 is a configuration example of a data set. Here, the power usage amount Wti and the total flow rate Qt collected by the data collection unit 11 are stored every time t.

The coefficient data 14B is data indicating an operation efficiency characteristic coefficient of a linear function approximating a characteristic in a negative side region where the flow rate change rate λ is smaller than 0 among the operation efficiency characteristics of each compressor Ci, that is, an intercept ai and a slope bi. is there.
FIG. 4 is a configuration example of coefficient data. Here, for each compressor Ci, an intercept ai and an inclination bi, which are operating efficiency characteristic coefficients, are stored.

  The coefficient calculation unit 15 selects m (= n × 2) data sets whose total flow rate Qt is decreasing from the data sets 14A stored in the storage unit 14 as target data sets Dt, and these Using the function for calculating the flow rate change rate λt per unit time for each Dt, the Qt for each Dt and the power consumption Wti, and the operation efficiency characteristic coefficients ai and bi for each compressor Ci, A function for generating m flow rate calculation formulas relating to Qti in equation (2) for each Dt, and a function for calculating ai and bi for each compressor Ci by solving these flow rate calculation formulas as simultaneous equations. ing.

  When the operation efficiency calculation unit 16 obtains the operation efficiency Uxi of the compressor Ci at an arbitrary time x, the operation efficiency characteristic coefficient of the compressor Ci is calculated based on the flow rate change rate λx at the time x based on the above-described equation (1). By multiplying bi and adding the operation efficiency characteristic coefficient ai of the compressor Ci, it has a function of calculating the Uxi and a function of displaying the obtained Uxi on the screen display unit 13.

[Operation of First Embodiment]
Next, operation | movement of the driving efficiency estimation apparatus 10 concerning this Embodiment is demonstrated.
First, with reference to FIG. 5, the coefficient calculation process in the driving efficiency estimation apparatus 10 will be described. FIG. 5 is a flowchart showing a coefficient calculation process in the driving efficiency estimation apparatus.
The coefficient calculation unit 15 executes the coefficient calculation process of FIG. 5 according to the operator operation detected by the operation input unit 12 or at regular time intervals. In the coefficient calculation processing, it is assumed that the data set 14A at each time t collected by the data collection unit 11 is stored in the storage unit 14 in advance.

  The coefficient calculation unit 15 first selects a data set at an unselected time t from the data set 14A in the storage unit 14 (step 100), and sets the total flow rate Qt of the data set by, for example, unit time from time t. Compared with the total flow rate Qt-1 measured before, it is confirmed whether Qt is decreasing (step 101). In this case, the flow rate change rate λt may be calculated first to confirm the sign of λt.

Here, when Qt ≧ Qt−1 (λt ≧ 0) (step 101: NO), the coefficient calculation unit 15 returns to step 100 and newly selects a data set at an unselected time.
On the other hand, when Qt <Qt−1 (λt <0) (step 101: YES), the coefficient calculation unit 15 extracts the data set as the target data set Dt and stores it in the storage unit 14 (step 102).

In this manner, the coefficient calculation unit 15 repeatedly executes data sets in which Qt is in a decreasing state until m data sets are extracted as Dt (step 103: NO).
When only Dt are extracted (step 103: YES), the coefficient calculation unit 15 assigns operation efficiency characteristic coefficients ai and bi for each compressor Ci (step 104), and a unit relating to the Qt for each Dt. A flow rate change rate λt per time is calculated based on the above-described equation (3) (step 105).

Subsequently, the coefficient calculation unit 15 generates m flow rate calculation formulas related to Qt of the above-described formula (4) for each Dt, using Qt and Wti for each Dt and ai and bi for each compressor Ci ( Step 106).
Thereafter, the coefficient calculation unit 15 generates simultaneous equations such as the above-described expression (6) from these m flow rate calculation expressions (step 107), and by solving this, ai and bi of each compressor Ci. (Step 108), the obtained ai and bi are stored as coefficient data 14B in the storage unit 14 (step 109), and the series of coefficient calculation processing is terminated.

Next, the driving efficiency calculation process in the driving efficiency estimation apparatus 10 will be described with reference to FIG. FIG. 6 is a flowchart showing a driving efficiency calculation process in the driving efficiency estimation apparatus.
The driving efficiency calculation unit 16 executes the driving efficiency calculation process of FIG. 6 according to the operator operation detected by the operation input unit 12 or at regular time intervals. In the operation efficiency calculation process, it is assumed that the operation efficiency characteristic coefficients ai and bi are stored as coefficient data 14B in the storage unit 14 for each compressor Ci calculated by the coefficient calculation unit 15.

  First, the operation efficiency calculation unit 16 refers to the data set 14A in the storage unit 14 and obtains the total flow rate Qx from the data set at an arbitrary time x designated as the operation efficiency target (step 110). Thus, the flow rate change rate λx is calculated (step 111).

  Thereafter, the operating efficiency calculation unit 16 acquires the operating efficiency characteristic coefficients ai and bi of the compressors Ci from the coefficient data 14B of the storage unit 14, and sets the ai and bi and the flow rate change rate λx to the above-described formula (1). By substituting into, the operating efficiency Uxi at time x is calculated for each compressor Ci (step 112).

  Further, the operating efficiency calculation unit 16 obtains the rated efficiency Uri of each compressor Ci stored in advance in the storage unit 14, and divides the value obtained by subtracting Uxi from Uri by Uri, thereby obtaining the operating efficiency deterioration rate Rxi. These are calculated (step 113), these are displayed on the screen display unit 13 (step 114), and the series of operation efficiency calculation processing is terminated.

  FIG. 7 is an example of an individual display screen for operating efficiency. Here, the operation efficiency Ux1 and the operation efficiency characteristic at a specific time x “11:00” regarding the compressor C1 among the compressors C1 to Cn are displayed in a graph, and the horizontal axis indicates the flow rate change rate λx. The vertical axis represents the operating efficiency Ux1 (basic unit). Further, the graph shows the rated efficiency Ur1 of the compressor C1, the operating efficiency deterioration rate Rx1 indicating the deterioration rate of the operating efficiency Ux1 based on the rated efficiency Ur1, the maximum efficiency Uxmax1 composed of the operating efficiency characteristic coefficient a1, and the operating efficiency characteristic coefficient The decrease rate Rdx1 of the operation efficiency Ux1 per unit flow rate change rate, which is composed of b1, is displayed together.

  With this individual display screen, the administrator can easily confirm under what circumstances the selected compressor Ci is operating at time x based on the operation efficiency Uxi and the operation efficiency deterioration rate Rxi. In addition, the maximum efficiency Uxmaxi can grasp the best efficiency obtained by the compressor Ci, and the reduction rate Rdxi details how much the operation efficiency Uxi decreases as the flow rate change rate λx decreases. Can be confirmed.

Moreover, FIG. 8 is an example of a list display screen of driving efficiency. Here, the operation efficiency Uxi, the rated efficiency Uri, the operation efficiency deterioration rate Rxi, the maximum efficiency Uxmaxi, and the decrease rate Rdxi at the time x described above are displayed in a list for each of the compressors C1 to Cn.
With this list display screen, it is possible to easily confirm the operation status and the operation efficiency characteristics regarding the compressors C1 to Cn at the time x, and to easily compare the compressors C1 to Cn.

[Effect of the first embodiment]
As described above, in the present embodiment, the coefficient calculation unit 15 selects m data sets whose total flow rate Qt is reduced from the data sets 14A stored in the storage unit 14 as target data sets Dt ( = N × 2) Selected and obtained for each target data set Dt, the flow rate change rate λt for the total flow rate Qt, the total flow rate Qt and the power consumption Wti, the flow rate change rate for each compressor Ci, and the operation Using the operation efficiency characteristic coefficients ai and bi indicating the intercept and slope of a linear function that approximates the relationship with efficiency, m flow rate calculation formulas for the total flow rate Qt are generated for each target data set Dt, and these By solving the flow rate calculation formula as a simultaneous equation, the operation efficiency characteristic coefficients ai and bi are calculated, and the operation efficiency calculation unit 16 calculates the flow rate change rate λx at an arbitrary time x in accordance with By multiplying the operating efficiency characteristic coefficient bi of suppressor Ci, by adding the operating efficiency characteristic coefficient ai of the compressor Ci, is obtained so as to calculate the operating efficiency Uxi of the compressor Ci at the time x.

  Thereby, the operation efficiency Uxi of each compressor Ci was obtained by the electric power consumption Wxi of each compressor Ci obtained by the wattmeter 8 previously installed in the general compressed air supply system 1 and the flow meter 4A. Calculated based on the total flow rate Qx. For this reason, it is possible to easily estimate the operation efficiency Uxi of each compressor Ci without requiring the addition of equipment such as a flow meter for measuring the flow rate data in the compressor Ci for each compressor Ci. It becomes. At this time, if the wattmeter 8 is not installed, it is necessary to add the wattmeter 8 for each compressor Ci, but it is not necessary to add a flow meter for each compressor Ci as in the prior art.

  In addition, since the operation efficiency can be estimated for each of the compressors C1 to Cn, each compressor C1 to Cn is actually selected by the individual display screen or list display screen of the operation efficiency as shown in FIG. 7 or FIG. The administrator can easily grasp whether the vehicle is operating with such driving efficiency. Thereby, the operation order in the unit control can be reviewed, and energy saving and CO2 saving can be realized. Further, it is possible to plan whether or not maintenance is required for each of the compressors C1 to Cn, and which compressor C1 to Cn is to be maintained in order, and is extremely useful for determining whether or not to replace the compressors C1 to Cn. Data can be provided.

  Further, in the present embodiment, a case has been described in which the coefficient calculation process in FIG. 5 and the operation efficiency calculation process in FIG. 6 are executed according to an operator operation or at regular intervals. At this time, since the operation efficiency characteristics of the compressors C1 to Cn do not change so rapidly, the coefficient calculation process may be automatically executed for several months or one year according to the maintenance cycle, for example. Good. Further, if the operation efficiency calculation process is always executed at regular intervals based on the latest overall flow rate Qx, the latest operation efficiency Uxi can be confirmed for each of the compressors C1 to Cn. Note that, based on the data set 14 </ b> A stored in the storage unit 14, the operation efficiency Uxi at the time x can be confirmed from the total flow rate Qx at the past arbitrary time x.

[Second Embodiment]
Next, the driving efficiency estimation device 10 according to the second exemplary embodiment of the present invention will be described.
In the present embodiment, generation of a target data set in the coefficient calculation unit 15 will be described.

  The coefficient calculation unit 15 calculates operating efficiency characteristic coefficients ai and bi of each compressor Ci by solving m flow rate calculation formulas as simultaneous equations. Here, when solving simultaneous equations in a computer, a desired calculation accuracy may not be obtained depending on the combination of flow rate calculation formulas used.

For example, the electric power consumption, total flow rate, and flow rate change rate measured at time t = 1 are W1i, Q1i, and λ1, respectively, and the electric power usage at compressor Ci measured at time t = 2. , When the total flow rate and the flow rate change rate are W2i, Q2i, and λ2, respectively, the flow rate calculation formula for these Q1i and Q2i is expressed by the following formula (5).

Further, when considering simultaneous equations composed of Expression (5), it is expressed by a determinant like Expression (6), and by solving this, unknown operation efficiency characteristic coefficients ai and bi are obtained.

  FIG. 9 is a graph showing simultaneous equations and their solutions, in which the horizontal axis represents ai and the vertical axis represents bi. Here, the flow rate calculation formula of Formula (5) is projected on the planes ai and bi as straight lines L1 and L2, and the solution S of the simultaneous equations of Formula (6) is obtained as the intersection of the straight lines L1 and L2.

Here, when the slope between the straight lines L1 and L2 is large, that is, when the normal vectors N1 and N2 of the straight lines L1 and L2 are greatly different, coefficients for determining the straight lines L1 and L2, here, measurement data Wi1, λ1 × W1i , Wi2, λ2 × W2i, even if an error is included in the coefficient matrix A composed of a square matrix, the intersection of the straight lines L1, L2, that is, the position of the solution S does not change much.
However, when the slope between the straight lines L1 and L2 is extremely small, that is, when the normal vectors N1 and N2 are substantially equal, the position of the intersection of the straight lines L1 and L2 changes greatly due to an error in the coefficient that determines the straight lines L1 and L2. Therefore, the error ε of the solution S increases, and the accuracy of the solution S decreases.

In addition, when solving simultaneous equations with a computer, it is possible to use various publicly available analysis software. However, in any analysis software, there is a trade-off between processing time and analysis accuracy. The solution calculation process is terminated in a certain processing time.
Therefore, when the slope between the straight lines L1 and L2 is extremely small, the position of the intersection of the straight lines L1 and L2 changes greatly even if the difference in the degree of the solution calculation process is terminated, and the error ε of the solution S Becomes larger.

  In the present embodiment, the coefficient calculation unit 15 determines the accuracy of the solution obtained from the target data set Dt, so that the sensitivity of the solution S is low to some extent, and the target is not easily affected by the measurement data and the solution calculation process being aborted. A data set is selected.

  That is, the coefficient calculation unit 15 according to the present embodiment uses the condition number κ (A) (Condition Number) relating to the coefficient matrix A of the simultaneous equations as an index indicating the sensitivity of the solution S to the coefficient change of such simultaneous equations. A function to calculate, a function to determine whether or not sufficient solution accuracy can be obtained from the target data set Dt by comparing the condition number κ (A) and the threshold value κth, and the condition number When κ (A) is larger than the threshold value κth, partial replacement of the data sets constituting the target data set Dt is repeated until the condition number κ (A) becomes equal to or less than the threshold value κth. It has a function to perform.

At this time, for the condition number κ (A), a known calculation method using a matrix norm may be used as shown in the following equation (7). In Equation (7), || A || is the matrix norm of the coefficient matrix A, and || A ^-1 || is the matrix norm of the inverse matrix A ^-1 of the coefficient matrix A. As for the matrix norm, various calculation formulas such as Frobenius norm and maximum norm exist, and it may be illuminated that these are equivalent (equivalent). In such a case, an arbitrary calculation formula may be selected and used based on an index such as a required calculation time and variations in the obtained operation efficiency characteristic coefficients ai and bi.

  The threshold value κth has a specific optimum value for each accuracy required for the configuration of the target compressed air supply system 1 and the management of the compressors C1 to Cn. It may be determined according to the number of significant digits, or may be determined empirically based on the obtained indicators such as variations in operating efficiency characteristic coefficients ai, bi, and the operator depending on the data acquisition situation May be determined according to the situation, such as changing or automatically changing.

[Operation of Second Embodiment]
Next, with reference to FIG. 10, operation | movement of the driving efficiency estimation apparatus 10 concerning this Embodiment is demonstrated. FIG. 10 is a flowchart illustrating target data set generation processing in the driving efficiency estimation device.
The coefficient calculation unit 15 executes the target data set generation process shown in FIG. 10 in step 107 of FIG.

First, the coefficient calculation unit 15 generates simultaneous equations such as the above-described equation (6) from the m flow rate calculation equations generated in step 106 of FIG. 5 (step 200), and a coefficient matrix A of the simultaneous equations. For example, the condition number κ (A) is calculated based on the above-described equation (7) (step 201).
Subsequently, the coefficient calculation unit 15 compares the condition number κ (A) with a threshold value κth preset in the storage unit 14 (step 202).

  Here, when the condition number κ (A)> threshold value κth (step 202: NO), the coefficient calculation unit 15 selects one data set not selected as the target data set Dt from the data set 14A. A new data set is selected (step 203). At this time, for example, the new data set may be selected in order from the newest data set that is older than the target data set Dt in the data set 14A. As a result, a data set that does not deviate from the selected target data set Dt can be selected as a new data set, and the influence on the error of the operation efficiency characteristic coefficients ai and bi due to the replacement of the data set is minimized. be able to.

Next, the coefficient calculation unit 15 selects one data set that has not been excluded from the target data set Dt as an excluded data set (step 204). At this time, as the excluded data set, for example, it is only necessary to select the data set that is not yet excluded from the target data set Qt and that is the oldest data set.
Subsequently, the coefficient calculation unit 15 replaces this excluded data set with a new data set (step 205), and then changes the flow rate per unit time with respect to Qt of the new data set in the same manner as step 105 in FIG. The rate λt is calculated based on the aforementioned equation (3) (step 206).

Thereafter, the coefficient calculation unit 15 uses the new data set Qt and Wti and ai and bi for each compressor Ci, similarly to step 106, to calculate the flow rate calculation formula for Qt in the above-described formula (2). m are generated (step 207), and the process proceeds to step 200.
As a result, for the new target data set Dt in which the excluded data set is replaced with the new data set, the solution accuracy determination of the target data set by the condition number κ (A) is repeatedly performed. At this time, it is repeatedly executed from the state in which the excluded data is restored.

  On the other hand, when the condition number κ (A) ≦ threshold value κth is satisfied in step 202 (step 202: YES), the coefficient calculator 15 has sufficient solution accuracy with the target data set Dt selected at that time. Since it is confirmed that the target data set is obtained, the target data set generation process is terminated, and the process proceeds to step 108 in FIG. 5 to execute the calculation process of the operating efficiency characteristic coefficients ai and bi by the simultaneous equations generated from the target data set Dt. To do.

[Effect of the second embodiment]
Thus, in the present embodiment, the coefficient calculation unit 15 calculates the condition number κ (A) related to the coefficient matrix A of the simultaneous equations, and compares the condition number κ (A) with the threshold value κth. Then, it is determined whether or not sufficient solution accuracy is obtained. When the condition number κ (A) is larger than the threshold value κth, until the condition number κ (A) becomes equal to or less than the threshold value κth, The target data set Dt is repeatedly exchanged.

  As a result, the target data set Dt that provides sufficient solution accuracy is automatically selected from the data set 14A, and the operating efficiency characteristic coefficients ai and bi are calculated. Therefore, it is possible to obtain the operation efficiency characteristic coefficients ai and bi with less error, in which the influence of the censoring of the measurement data and the solution calculation process is reduced.

[Extended embodiment]
The present invention has been described above with reference to the embodiments, but the present invention is not limited to the above embodiments. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention. In addition, each embodiment can be implemented in any combination within a consistent range.

  In each embodiment, for example, a plurality of data sets Dt are passed to the coefficient calculation unit 15 to calculate a plurality of operating efficiency characteristic sets ai and bi, and standard deviations of ai and bi are calculated. If the variation is smaller than the required variation, the calculation may be terminated.

  In each embodiment, the compressed air supply system that generates compressed air by the compressor and supplies it to the load has been described as an example of the target for estimating the operation efficiency. However, the present invention is not limited to this. Other than the above, for example, the embodiments can be applied to other systems such as a compressed gas supply system that compresses a mixed gas such as a refrigerant and supplies the compressed gas to the load in the same manner as described above. .

  DESCRIPTION OF SYMBOLS 1 ... Compressed air supply system, C1-Cn, Ci ... Compressor, 2, 4 ... Pipe line, 3 ... Tank, 4A ... Flow meter, 5 ... Header, 5A ... Pressure gauge, 6 ... Load, 7 ... Compressor control part, 8 (81 to 8n) ... Wattmeter, 10 ... Driving efficiency estimation device, 11 ... Data collection unit, 12 ... Operation input unit, 13 ... Screen display unit, 14 ... Storage unit, 14A ... Data set, 14B ... Coefficient data, 14P ... Program, 15 ... Coefficient calculation unit, 16 ... Operation efficiency calculation unit, Qt, Qx ... Overall flow rate, Wt1 to Wtn, Wti, Wxi ... Power consumption, Dt ... Target data set, λt, λx ... Flow rate change rate, ai ... operating efficiency characteristic coefficient (intercept), bi ... operating efficiency characteristic coefficient (slope), Uti, Uxi ... operating efficiency, Uri ... rated efficiency, Rxi ... operating efficiency deterioration rate, Uxmaxi ... maximum efficiency, Rdxi ... reduction rate, S ... solution, κ (A): number of conditions, κth: threshold value.

Claims (3)

An operating efficiency estimation device that individually estimates the operating efficiency of n (n is an integer of 2 or more) compressors Ci (i = an integer of 1 to n) that are operated in parallel,
At each time t, a power usage amount Wti indicating individual power used by each compressor Ci and an overall flow rate Qt indicating the total flow rate of compressed air supplied from the compressor Ci are collected, and these power usage amounts are collected. A data collection unit for storing Wti and the total flow rate Qt in the storage unit as a data set of the time t;
From the data sets stored in the storage unit, m (= n × 2) data sets in which the overall flow rate Qt is in a decreasing state are selected as target data sets Dt, and for each target data set Dt The obtained flow rate change rate λt for the total flow rate Qt, the total flow rate Qt and the power consumption Wti, and the intercept and slope of a linear function that approximates the relationship between the flow rate change rate and the operating efficiency for each compressor Ci. Using the operational efficiency characteristic coefficients ai and bi shown,

Are generated for each target data set Dt, and the flow rate calculation formulas are solved as simultaneous equations, thereby calculating the operating efficiency characteristic coefficients ai and bi; ,
By multiplying the flow rate change rate λx at an arbitrary time x by the operation efficiency characteristic coefficient bi of the compressor Ci and adding the operation efficiency characteristic coefficient ai of the compressor Ci, the operation efficiency Uxi of the compressor Ci at the time x An operation efficiency estimation device comprising: an operation efficiency calculation unit that calculates In the driving efficiency estimating device according to claim 1,
The coefficient calculation unit calculates a condition number κ (A) (Condition Number) related to the coefficient matrix A of the simultaneous equations, and compares the condition number κ (A) with a threshold value κth, thereby obtaining the target data. It is determined whether sufficient solution accuracy can be obtained from the set Dt. If the condition number κ (A) is greater than the threshold value κth, the condition number κ (A) is equal to or less than the threshold value κth. The driving efficiency estimation device is characterized by repeatedly performing partial replacement of data sets constituting the target data set Dt.   The program for functioning a computer as each part of the driving | running efficiency estimation apparatus of Claim 1 or Claim 2.

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