JPS5930915B2 - Pump number characteristic linearization device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pump number characteristic linearization device that linearizes a pump number characteristic that exhibits nonlinear characteristics.

Pumping facilities are widely used in various systems such as water supply, sewerage, irrigation, and oil pipelines, but recently, from the perspective of energy conservation, it has become necessary to optimally operate the pumps in these types of pumping facilities. It has become.

In this case, if the characteristics of the number of pumps are linear, optimal control can be easily achieved because it results in solving a so-called linear programming problem.

However, the actual characteristics of the number of pumps are non-linear, which is one of the reasons that is hindering the development of a system that can control the operation of pump facilities under optimal conditions at all times.

In other words, in the past, a method of controlling the number of pumps according to a predetermined sequence based on the pump load pattern has been widely used.

An object of the present invention is to provide a device that linearizes the number of pumps characteristics exhibiting nonlinear characteristics so as to minimize the error thereof, thereby easily realizing a system that optimally controls the number of pumps. be.

Hereinafter, the content of the present invention will be explained in detail.

Figures 1 and 2 are diagrams for explaining the present invention in detail. Figure 1a shows the actual operating number characteristics of the pumps, the same figure shows the linearization characteristics, and Figure 2 shows the characteristics of the present invention. The processing flow is shown below.

First, the maximum number of operating pumps N is initially set as the division number M (a).

Next, the maximum delivery amount PN when the maximum number of operating units is N is divided into M to obtain a unit division characteristic value Ad Ad=PN/M (1) (Ex.).

Next, Ad is multiplied by n (j=1.2°...N) to 1~
rt to obtain the linear approximation characteristic value P'j P'j-nj-Ad (2) of each pump characteristic corresponding to N pumps, that is, as shown in Figure 1, 1 to N Each pump characteristic is linearly approximated.

Next, calculate the cumulative error E between the linear approximation characteristic value Pj and the pump mounting characteristic Pj).

The above process is repeated a predetermined number of times by changing the number of divisions MK (E, E).

Next, for the large number of cumulative errors E obtained, the division number V that minimizes the E is determined (l-).

Ad for this division number M' is Ad', nj is Ad'.

′j furnace, the optimal approximate delivery amount P is P j= n
'j-A'd (4).

P1tP2t...PN (-PN) obtained in this way is the actual characteristic value P1. It will be easily understood that P2... exhibits linearization characteristics for PN.

Table 1 shows an example of the characteristics of the number of pumps when there are three pumps.For convenience, the water flow rate when one pump is operated is 900.
This is an example in which the nonlinear characteristic is y4/hour, 1080-7 hours in the case of two-unit operation, and 12007729/hour in the case of three-unit operation.

The following explanation will be based on this example, but it goes without saying that it is generally applicable to the operation of N vehicles.

The following Table 2 shows the procedure for linearizing the nonlinear characteristics of this pump using arithmetic calculations in order to make it easier to understand.

This is calculated by dividing the maximum water flow rate of 1200 m''/hour fM (in this example, dividing into 3 to 10) when the maximum number of operating units (this = 7) [3 units in Fl. 1
It attempts to approximate the characteristics of single-unit operation, two-unit operation, etc., and even the characteristics of N-unit operation.

In the example of Table 2, first, when 1200772'/hour is divided into three, the unit division characteristic is 400 d1 hours.

The actual number of pump characteristics is 900 d/ when one pump is operated.
Therefore, in order to express this characteristic within 1200 d/hour and as an approximate characteristic of a multiple of the unit division characteristic 400771'/hour, it is approximated by 800 d/hour.

At this time, the error from the actual characteristics is 100 d/hour.

Next, in the case of two-unit operation, the approximate characteristic of 1080771'/hour is approximated to 1200 i/hour in the same way as above.

At this time, the error from the actual characteristics is 120 d/hour.

Of course, when operating 3 units, the error is O at 1200 d/hour.
It is.

Similarly, it can be divided into 4, 5, . . . M divisions.

Table 2 shows the pump approximation characteristics for each division from 3 to 10 and the errors at that time.

Among these divisions, the selection of the optimal approximation can be determined as the one with the minimum sum of these errors as the optimal one (
The optimal number of divisions may vary depending on the evaluation method).

FIG. 3 shows the relationship between mesh points and actual characteristics, taking as an example three divisions among the divisions in Table 2.

FIG. 4 shows an approximation method for linearly approximating the actual characteristics shown in FIG.

Figure a shows the actual characteristic 900771'/ when one pump is operated.
It shows how the hour is approximated to 400 d/hour, which is a multiple of 7 o'clock to 800 d/hour.

Figure b shows how the actual characteristic of 1080 d/hour is approximated to 1200 d/hour, which is a multiple of 400 d/hour, when two pumps are operated.

FIG. 5 shows the components of the present invention functionally divided into blocks, with solid lines representing data and broken lines representing the flow of commands.

Characteristics of one pump, characteristics of two pumps,
. . . The characteristics 110 of each number-of-units operation, such as the characteristics in the case of N units, are stored in the storage device 102.

The required number characteristic 111 of the number of pumps stored in this way is read out in response to a memory read command 128 from the control device 101 and inputted to the linear approximation calculation device 103 for the number of pumps.

On the other hand, the division number determination device 105 is driven based on the division number determination command 120, and the division number determination device 105 is driven to give a 3 division command, a 4 division command, etc.
..., division commands 113 such as M division commands are also input to the pump number linear approximation calculation device 103.

In this device, the actual characteristics of the pump are calculated by linear approximation in accordance with the maximum division so that the characteristics are placed on the mesh points.

In the device 104 that calculates the error between the mesh point and the actual pump characteristic based on the linear approximation 112 by this device, as shown in FIG. The approximate points are the mesh points of 800 m/h and 1200771'/h, and between these points the actual characteristic P1 in figure a is 9.
In order to approximate the example of 00 d/hour and the example of P2 of 1 oso */ hour in figure b to either of these points, calculate the error when approximating to each point, and calculate this by Calculations are simultaneously performed in which the one with the smaller error is determined as an approximate solution. When the calculation is completed, an approximate calculation end command 122 is issued.

Pump number linear approximation calculation device 103 and error calculation device 10
Based on the respective outputs 114 and 115 of 4, the approximate characteristics of the pump according to the respective division numbers are sequentially stored in the storage device 108.

Reference numeral 123 indicates an N-unit approximate characteristic storage end command, and 124 indicates a number-of-unit approximate characteristic write command.

Regarding the approximation error 116, upon receiving an error write command 127 from the device 104, the cumulative error storage device 106 calculates and stores the cumulative error of approximation for each division number.

Next, the optimal error calculation command 121 is received from the device 101, and based on the cumulative error 117, the minimum error determining device 107 determines the number of divisions with the smallest cumulative error.

Next, based on the optimal division number command 125 obtained by the device 107, the optimal pump approximate characteristics 11 are stored in the storage device 108.
9 is called, and the accumulated error 118 and the information at this time are sent to the output device 109 and output.

Note that 126 is an optimal error calculation end command.

FIG. 6 shows a specific embodiment of the present invention.

In this section, details of the operation will be described using Tables 1 and 2 as examples.

Characteristics of number of pumps: 1 pump, 2 pumps, etc.
...In the case of N units, input and store in the storage device 3.

As a result, the contents of Table 3 below are stored in the storage device 3.

Next, the N pump characteristic values 4, which are the maximum pump characteristics, are divided by the division number signal 35 via the divider 22 to calculate a unit division characteristic value 37.

In other words, first divide 1200m/hour into 3 parts and get 400m'
/Calculate the hour.

The division number represented by the division number signal 35 is specified by opening and closing the switch 19 and driving the 1 adder 20 in response to the division command signal 49 from the division number control device 1.

That is, the number of times the switch 19 is opened/closed is increased by three divisions, four divisions, . . . , and ten divisions.

On the other hand, the target switch in the switch 18 is opened and closed by the read signal 50 of the memory read control device 2 71 . OR circuit 4
In the case of one pump, in the case of two pumps, . . . in the case of N pumps, the pump characteristic values 36 are read out in order.

First, the characteristic value 900772''/hour for the case of one unit is read out.

This pump characteristic value 36 is divided by a unit division characteristic value 37 via a divider 5, and then an integer value is obtained via an integer converter 6.

In other words, for one unit, 900 d/hour is reduced to 400 d/hour.
Divide by time and quantize to calculate 2.

Next, this value is multiplied by the unit division characteristic value 37 via a multiplier 7 to obtain an approximate characteristic of the pump.

In other words, in the case of one unit, s o O at 2 x 400 m'/hour
, = It will be 7 o'clock.

This value is converted into a negative characteristic value through a sign converter 8, and the Q difference from the actual characteristic value 36 is taken by an adder 9 to calculate a positive approximation error 38 (actual value) (error when approximated by the approximate value).

That is, in the case of one unit, there will be an error of 900-800=100 d/hour.

Next, in order to determine whether or not the approximation is optimal, this positive approximation error value 38 is passed through a multiplier 10 by 2.
This is doubled, passed through a sign converter 11 to a negative value, and an adder 12 calculates the difference with the unit division characteristic value 31 for comparison.

This output passes through the relay drive circuit 13 to the relay 16.
Open and close.

When ON, that is, when the unit division characteristic value 37 is larger than twice the positive approximation error 38, the error will be smaller if the pump characteristics are approximated by a mesh point value smaller than the actual characteristics, and this approximation will reduce the error. Show that it is optimal.

If it is OFF, that is, when the unit division characteristic value 31 is smaller than twice the positive approximation error 38, the error will be smaller if the pump characteristics are approximated by a mesh point value larger than the actual characteristics, and the approximation will be It is necessary to approximate using a mesh point larger than the actual measurement value.

At this time, the negative approximation error 41 (approximate value>actual value) is the value obtained by subtracting the unit division characteristic value 31 from the positive approximation error 38 by the adder 15 through the sign converter 14.

Positive approximation error 38 selected 0N-OFF with switch 16
The error value of either the negative approximation error 41 or the negative approximation error 41 is squared by the multiplier 27 and supplied to the addition storage device 28 through all the switches 30.

In this way, the approximation error of each pump number characteristic with respect to the number of divisions is calculated, and then the number of divisions is advanced to the next value and the same process is repeated.

The addition storage device 28 consists of units for M divisions, and cumulative errors are stored for each division number.

As a result, the contents stored in the storage device 28 are finally as shown in Table 4 below.

However, in this example, the number of mesh divisions is M=3 to 10.

On the other hand, for each division number, the approximate characteristic value of each pump number characteristic is a value obtained by selecting either a value 54 obtained by converting the positive approximation error 38 through a sign converter 53 or a negative approximation error 41 using a switch 55. and the pump's actual measured value characteristic 36 are added by an adder 51 to obtain this value, and this value is stored in the storage device 24 via the switch 23.

As a result, Table 5 is stored in this storage device 24.

When the cumulative error and the approximate characteristic value of the pump are all stored in the storage device 28 and the storage device 24, the minimum error determining device 32 determines the number of divisions that minimizes the cumulative error based on the control device 10 command 48.

In this case, the eight divisions shown in the outline of Tables 4 and 5 are determined as the optimal division, and the corresponding cumulative error 45 and approximate characteristic value 43 are outputted through the output device 33.

Note that the switch switching command 50 of the control device 2 is
Each time 6 is opened or closed, the opening/closing signal 47 is output.

Further, the switch switching command 49 of the control device 1 is transmitted to the storage device 2.
4 outputs a termination signal 49 each time the approximate characteristics for up to N cars are input, and is driven based on this signal.

[Brief explanation of drawings]

Figure 1 is a diagram showing the relationship between the nonlinear characteristic of the number of pumps in operation and its kneading characteristic, Figure 2 is a diagram showing the processing flow according to the present invention, and Figure 3 is a diagram showing the relationship between the number of pumps and the mesh point depending on a certain constant. FIG. 4 is a diagram showing the relationship with division; FIG. 4 is an explanatory diagram when the pump characteristics in FIG. 3 are approximated by multiples of the division constant; FIG. 5 is a functional block diagram of an embodiment of the present invention; The figure shows a concrete embodiment of the invention. In FIG. 5, 101... control device, 102
... Storage device, 103 ... Pump number linear approximation calculation device, 104 ... Error calculation device,
105... Division number determining device, 106...
- Cumulative error storage device, 107... Minimum error determining device, 108 - Music storage device, 109... Output device.

Claims (1)

[Claims] 1 In a pump number characteristic linearization device that linearizes and calculates the number characteristics of pumps exhibiting nonlinear characteristics so as to minimize the error, the maximum delivery amount PN for the maximum number of operating units (N units) is divided into M. division number determining means for calculating the unit division characteristic value PN/M;
~ Approximation calculation means for linearly approximating the characteristics of each of the N pumps,
an error calculation means for calculating the cumulative error between each of the linearly approximated characteristic values obtained by the linear approximation and the actual characteristic value of the pump; a control means for instructing to repeat the processing of each of the above means by changing the number of divisions M; and the repeating process. a minimum error determining means for determining the number of divisions at which the accumulated error obtained is the minimum; and an output means for outputting an output as follows.