JPH1185205A - Method and device for generating artificial two-input polygonal function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily generate an artificial two-input polygonal function only by the function that a normal controller has by preparing one-input polygonal functions of a 1st and a 2nd input variable, multiplying output values obtained by substituting respective input variables in corresponding one-input polygonal functions by arbitrary values, and adding multiplication values in order. SOLUTION: For example, when this method and device are applied to a supermotor steam output temperature controller of a coal fired power generation unit, one-input polygonal function generators FX (FX-1 to FX3) 11 to 13 use coal property indexes X different with kinds of coal as input variables and one-input polygonal function generators FY (FY-1 to FY3) 21 to 23 use the variable load index Y of the fired power generation unit as input variables. Multipliers 31 to 33 multiply the outputs of the polygonal function generators FX11 to FX13 and FY21 to FY23 and adders 41 and 42 are add the outputs of the multipliers 31 to 33 in order. The subtracter 51 of an arithmetic circuit finds deviation of spray valve exit temperature from set temperature and a PI controller 52 calculates a correction value to control the opening extent of a spray valve 50 through an adder 53.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for generating a pseudo two-input linear function, and more particularly, to a two-input one-output linear function used for a control device, an operation support device, a monitoring device and the like in a plant. The present invention relates to a method for creating a pseudo two-input linear function, which is realized by a one-input linear function using a linear function unit, a multiplier, and an adder included in a control device, and an apparatus therefor.

[0002]

Conventionally, a one-input, one-output broken-line function generator for setting a valve opening output, for example, using temperature as a detection input signal, is a control device, an operation support device, a monitoring device in a plant, for example. It is a widely used element. On the other hand, the technology to set one valve opening output by two detection input signals such as temperature and pressure, and to control the SH outlet temperature of a multi-coal coal-fired power generation unit, In the case of the technique of setting the spray valve advance opening signal based on the two input signals of the index and the load index, an arithmetic device that obtains the respective output signals using a two-input one-output linear function generating circuit, It is often used in actual plant control.

In order to realize a two-input, one-output linear function in these plant controllers and the like, as shown in FIG. 1, a cubic function consisting of three-axis coordinates of two inputs (X, Y) and one output (Z) is used. It was necessary to prepare a two-input one-output linear function for generating the original coordinate map, and the production thereof required a lot of trouble and a complicated analysis circuit.

The problem of the prior art will be described with reference to FIG. 1. FIG. 1 is a graph showing YZ based on one input variable (Y) and output (Z) out of the two input variables and one output. The two-dimensional coordinate of the axis is calculated by using another input variable (X) and output (Z).
-Two-dimensional Z-axis coordinates are formed, and the X-axis
-The three-dimensional coordinates of the YZ axes are formed, and the output (Z) on the corresponding coordinates is obtained.

That is, in FIG. 1, as an example, the one-input linear function of the YZ axis at X = X ₁ is FY-1, the linear function of the YZ axis at X = X ₂ is FY-2, and X = X 2. the polygonal line function of Y-Z axis coordinate respectively formed by a thick fold line of FY-3 in X _3. In FIG. 1, the cut surface formed by the broken line function of FY-1 at X = X ₁ is a hatched portion represented by the portion (A), and is formed by the broken line function of FY-2 at X = X ₂ . The cut surface to be formed is a hatched portion represented by a portion (B), and an X- line composed of two inputs (X, Y) and an output (Z) is formed by many combinations of these hatched portions.
A three-dimensional coordinate map of the YZ axes is formed.

Therefore, in order to realize a two-input one-output polygonal function, in the prior art, a three-dimensional coordinate map consisting of two-input (X, Y) and one-output (Z) three-axis coordinates as shown in FIG. After formation, the output Zp is determined. However, obtaining the output Zp from the three-dimensional coordinate map requires a lot of trouble and a complicated analysis circuit to create the map as described above.

SUMMARY OF THE INVENTION In view of the above technical problems, the present invention provides a method for easily creating a pseudo two-input linear function using only the functions (a linear function of one input and one output) possessed by a normal control device. With the goal.

[0008]

Therefore, the present invention provides a method for creating a pseudo two-input linear function that obtains one output from two input variables. Prepare one input linear function with two input variables,
After obtaining a multiplied value for each arbitrary value by multiplying the first and second output values obtained by inputting the respective input variables to the one-input linear function corresponding to each arbitrary value, A pseudo two-input linear function creation method is proposed in which a multiplied value for each arbitrary value is sequentially added to obtain one output.

According to a second aspect of the present invention, there is provided a pseudo two-input linear function generator for obtaining one output from two input variables, wherein the one-input linear function generator for the first input variable and the second input variable A one-input linear function generator, and for each arbitrary value obtained by multiplying the first and second output values obtained by inputting the respective input variables to the one-input linear function corresponding to each arbitrary value, And an adder for sequentially adding the multiplied values for each of the arbitrary values to obtain one output. .

Hereinafter, the present invention will be described with reference to FIGS. In FIG. 1, a three-dimensional surface (A) between functions FY-1 and FY-2
Is equivalent to the hatched portion represented by the portion (A) in FIG. Also, a three-dimensional surface (B) between the functions FY-2 and FY-3
Is equivalent to the hatched portion represented by the portion (B) in FIG.

That is, to explain more specifically, the value of the output Z _{1 at} the _first input variable X = X ₁ is located on the broken-line function line of FY-1 and therefore the second input variable Y = Yp if is determined, the output Z ₁ is determined as FY-1 (Yp). Also the first
The value of the output Z ₂ and the input variable X = X ₂ of the second input variable Y = Yp of is determined similarly as FY-2 (Yp).
Thus, for example, A point shown in FIG. 1 in the second input variable Y = Yp, respectively b is _{A: {X 1, Yp, Z} 1} = {X 1, Yp, FY-1 (Yp)} ... 1) A: {X ₂ , Yp, Z ₂ } = {X ₂ , Yp, FY-2 (Yp)}... 2), and the three-dimensional coordinate position of the output Z can be determined by the known input variables and the broken line function FY. It can be understood.

Further, as shown in FIGS. 1 and 2 (D), the coordinate position of an arbitrary point c on the line segment connecting the points a and a is determined by a first input variable X = Xp and a second input variable X = Xp. Input variable Y = Yp
Is determined by the output Zp together, the output Zp passes through the output Z ₁ and the output Z _2, X in the input point (Yp)
-It can be understood that it is located on the broken line function FX-1 (Xp) which is a cutting plane parallel to the Z axis. Therefore, the output Zp is equal to the input point (Xp
) Is a section line parallel to the YZ axis
It is located at the intersection of Yp and the polygonal line function FXp which is a cutting plane parallel to the XZ axis on the input point (Yp). Therefore, it is possible to express the output Z using the polygonal line function FX together with the polygonal line function FY. .

That is, the output Zp is Zp = {FX-1 (Xp)} × {FY-1 (Yp)} + {FX-2 (Xp)} × {FY-2 (Yp)}... Is expressed. As described above, the two-input linear function can be expressed by a combination of the one-input one-output linear function. An output Zp 'located at a coordinate position of an arbitrary point o on a line segment connecting the points a and e with the second input variable Y = Yp' shown in FIGS. As is clear from the above equation (3), Zp ′ = {FX-2 (Xp ′)} × {FY-2 (Yp ′)} + {FX-3 (Xp ′)} ×× FY-3 (Yp ')｝ ... 4).

As is clear from the results of these calculations, the above equations 3) and 4) are combined and located at the coordinate position of an arbitrary point E or E on the line segment connecting points A, A and E. Output Z
q is as follows: Zq = {FX-1 (Xq)} × {FY-1 (Yq)} + {FX-2 (Xq)} × {FY-2 (Yq)} + {FX-3 (Xq)} × {FY-3 (Yq)}... 5).

Therefore, from equation (5), the one-input linear function {FX-1 to FX-n} of the first input variable and the one-input linear function {FY-1 to FY-n} of the second input variable are obtained. Prepared and multiplied by the first and second output values obtained by inputting the respective input variables to the one-input linear function corresponding to each arbitrary value, multiplied value for each arbitrary value ｛FX -1 (Xq)｝ × ｛FY-1 (Yq)｝..., And then sequentially adds the multiplication value of each arbitrary value ｛FX-1 (Xq)｝ × ｛FY-1 (Yq)｝. Thus, it can be understood that one output Zq is obtained.

Similarly, as shown in FIG. 4, the present invention provides a one-input linear function generator {FX-1〜
FX-n｝ 11-13 and a one-input linear function generator ｛FY-1〜FY-n｝ 21-23 of a second input variable, and the one input corresponding to each of the input variables for each arbitrary value Multipliers 31 to 33 for obtaining a multiplied value for each arbitrary value by multiplying the first and second output values obtained by inputting the linear function and sequentially multiplying the multiplied values for the arbitrary value It can also be understood that the present invention can be achieved by a pseudo two-input broken-line function creating apparatus, which is provided with adders 41 to 42 for obtaining one output.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, and are merely illustrative examples. Only. FIG. 4 is a block circuit diagram showing an embodiment in which the present invention is applied to a super motor steam outlet temperature control device of a coal-fired power generation unit. The present embodiment uses, as two input variables, a coal property index (X) that differs depending on the type of coal used for fuel and a variable load index (Y) of the thermal power generation unit, and a spray valve advance signal of the thermal power generation unit. Let it be an output variable (Z). In FIG.
X (FX-1, FX-2, FX-3) 11, 12, and 13 are coal property indicators
One-input linear function generator with (X) as input variable, FY (FY-
1, FY-2, FY-3) 21, 22, 23 are one-input linear function generators using the unit variable load index (Y) as an input variable, 31,
32 and 33 are linear function generators FX (FX-1, FX-2, FX-3) 1
1,12,13 and FY (FY-1, FY-2, FY-3) 21,22,2
3 are multipliers for multiplying respective outputs of the multipliers 3, 41 and 42 are adders for sequentially adding output values of the multipliers 31, 32 and 33,
These calculation elements are incorporated in the CPU.

On the other hand, the arithmetic circuit on the side of the spray valve 50 comprises a subtractor 51, a PI controller 52, and an adder 53. The subtractor 51 obtains a difference (difference) between the spool valve outlet temperature and the set temperature. The deviation amount is input to the PI controller 52,
Calculate the correction value. The correction value is added to the output signal from the terminal side adder 41 in the CPU, that is, the spray valve advance output signal, by the adder 53, and the spray valve 50 is controlled based on the output signal from the adder 53. The opening is controlled.

Next, the operation of the above embodiment will be described. FIG.
The function graph of the one-input linear function generator (FX-1) 11 using the property index (X-1) of the first coal type as an input variable is set for the linear function (FX-1) shown in (A). Therefore, when the input variable X of the first coal type is X ≦ X ₁ , FX ₁ −1 = 1.0 when X ₁ <X ≦ X ₂ FX ₁ −1 = 1− (XX ₁ ) / (X ₂ −X ₁ ) When X ₂ <X, an output value of FX ₁ −1 = 0.0 is generated, and the output value is input to the multiplier 31.

The broken line function (FX-2) shown in FIG.
The function graph of the one-input linear function generator (FX-2) 12 using the property index (X-2) of the coal type is set as an input variable. Therefore, the input variable X of the second coal type is X _{≦ X FX 1 -2 = 0.0 X} 1 when ₁ <FX ₁ when _{X ≦ X 2 -2 = (XX} 1) / (X 2 -X 1) X 2 < when X ≦ X ₃ FX ₁ -2 = 1− (XX ₂ ) / (X ₃ −X ₂ ) When X ₃ <X, an output value of FX ₁ −2 = 0.0 is generated, and the output value is input to the multiplier 32.

The broken line function (FX-3) shown in FIG.
The function graph of the one-input linear function generator (FX-3) 13 using the coal type property index (X-3) as an input variable is set. Therefore, the input variable X of the second coal type is X _{≦ X FX 1 -3 = 0.0 X} 2 when ₂ <FX ₁ when _{X ≦ X 3 -3 = (XX} 2) / (X 3 -X 2) X 3 < when X FX ₁ -3 = 1.0 of An output value is generated, and the output value is input to the multiplier 33.

Next, as explained in the above-mentioned technical means, expression 5), the first input variable X = Xq and the second input variable Y = Yq
The equation for obtaining the output Zq, that is, the spray valve advance output signal, is disclosed in Equation 5).
The spray valve preceding output signal Zq is {FX-3 (Xq)} ×｝ FY-3
(Yq)｝ output value (computed value) A and {FX-2 (Xq)} × ｛FY-2
(Yq)｝ output value (computed value) B and {FX-1 (Xq)} × ｛FY-1
(Yq)｝ is the value obtained by adding the output value (calculated value) C of｝.

Therefore, the output of the {FX-3} function generator 13 and the output of the {FY-3} function generator 23 are multiplied by the multiplier 33 to obtain {FX-3 (Xq)} × {FY-3 (Yq). The output value A of｝ is obtained. Next, the output of the {FX-2} function generator 12 and the output of the {FY-3} function generator 22 are multiplied by a multiplier 32 to obtain {FX-2 (Xq)} × {FY-
An output value B of 2 (Yq)｝ is obtained. Further, the multiplier 31
An output value C of {FX-1 (Xq)} × {FY-1 (Yq)} is obtained by multiplying the output of the {-1} function generator 11 and the output of the {FY-1} function generator 21. Next, the output values A,
By adding B and C, a spray valve advance output signal Zq (A + B + C) shown in the above equation (5) can be obtained.

The spray valve advance output signal Zq
(A + B + C) and in the arithmetic circuit on the spray valve 50 side,
The correction value from the PI controller 52 is added by the adder 53, and the opening of the spray valve 50 can be controlled based on the added signal. In the present embodiment, the method of the present invention is described as a control device that is applied to SH outlet temperature control of a plant (coal-fired power generation unit) using a high coal type. It can be easily understood that the present invention can be applied to other models as long as it is controlled by the broken line function.

[0025]

As described above, according to the present invention, a two-input linear function is converted into one input and one output without using a method such as incorporating a two-input linear function into another device or using a dedicated arithmetic element. Can be expressed by the broken line function of
Further, according to the present invention, a two-input linear function can be realized by a one-input one-output linear function without specially incorporating a two-input function. Further, by combining the function of the linear function with one input and one output with a function that can be automatically changed, it is possible to flexibly cope with a process amount having aging. And so on.

[Brief description of the drawings]

FIG. 1 shows one input variable (Y) of the two input variables and one output.
And the output (Z) to form two-dimensional coordinates on the YZ axis, and the other input variables (X) and the output (Z) to form two-dimensional coordinates on the XZ axis. It is a three-dimensional coordinate graph figure which forms the three-dimensional coordinate of YZ axis | shaft, and calculates | requires output (Z) on the corresponding coordinate.

[Fig. 2] Input variables X of the coal property index are arbitrary values X ₁ , X ₂ ,
Polygonal line function FY-1 the relationship between the input variable Y output Z and the load index in _{X 3 (A), FY-} 2 (B), the output Z of the FY-3 (C) and object by adding these The respective graphs (D) are shown.

[Figure 3] The input variable X of the coal property index is an arbitrary value X ₁ , X ₂ ,
Polygonal line a relationship in X ₃ function FX-1 (A), FX -2
(B) and a graph diagram represented by FX-3 (C) are shown, respectively.

FIG. 4 is a block circuit diagram showing an embodiment in which the present invention is applied to a superheater steam outlet temperature control device of a coal-fired power generation unit.

[Explanation of symbols]

X Coal property index Y Load index Z Spray valve advance signal 11,12,13 One-input linear function generator 21,22,23 with coal property index (X) as input variable Unit variable load index (Y) as input variable One-input linear function generator 31, 32, 33 Multiplier 41, 42 Adder 50 Spray valve 51 Subtractor 52 PI controller 53 Adder

Claims (2)

[Claims] 1. A method for creating a pseudo two-input linear function that obtains one output from two input variables, comprising: providing a one-input linear function for a first input variable and a one-input linear function for a second input variable. After multiplying the first and second output values obtained by inputting each of the input variables to the one-input linear function corresponding to each arbitrary value to obtain a multiplied value for each arbitrary value , A pseudo two-input linear function creation method characterized by sequentially adding the multiplied values for each arbitrary value to obtain one output. 2. A pseudo two-input linear function generator for obtaining one output from two input variables, comprising: a one-input linear function generator for a first input variable and a one-input linear function generator for a second input variable. Multiplying a first and second output value obtained by inputting each of the input variables to the one-input linear function corresponding to each arbitrary value to obtain a multiplied value for each arbitrary value A pseudo two-input linear function creation device, characterized by comprising: an adder; and an adder for sequentially adding the multiplied values for each arbitrary value to obtain one output.