JP2015135219A - Boiler fuel input determination device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a boiler fuel input determination device capable of verifying whether or not a ratio target set in a boiler fuel reducing system is optimal and automatically changing the ratio target.SOLUTION: There are provided data number distribution confirmation/standard deviation evaluation means 34, 35to 35, 36to 36, 37, 38 for confirming a distribution of the number of pieces of data of a ratio Ki between input requirement steam amount A and requirement steam amount B for every renewal time and at the same time evaluating either fuel charging amount Fueli or main steam pressure Pi in reference to the standard deviation for every renewal time; and state determination means 39 for determining whether or not a ratio target set in a boiler fuel reducing system is optimal in reference to a result of evaluation by the data number distribution confirmation/standard deviation evaluation means, determining a corrected ratio Goiii for changing the ratio target upon determination that the ratio target is not optimal and inputting the determined corrected ratio Goiii into fuel correction coefficient calculation means 15, 16 in place of the ratio Ki.

Description

  The present invention relates to a boiler fuel input amount determination device suitable for correcting an amount of fuel input to a boiler and determining an appropriate fuel amount corresponding to a required steam amount (required load amount) of the boiler.

  Power generation using boiler equipment is performed by supplying fuel to the boiler, absorbing the heat burned by the heat exchanger, supplying the generated steam to the turbine, and outputting it from the generator. Is constantly affected by various disturbances (outside air temperature, fuel properties, etc.), and the combustion state fluctuates. Originally, if the influence of such disturbance can be accurately fed back to the boiler control and the control parameters can be optimized sequentially, stable operation can be achieved without much influence from the disturbance.

Conventionally, however, it has been difficult to properly grasp such disturbances. However, a boiler fuel input determining device (hereinafter referred to as “conventional boiler fuel”) for a boiler fuel reduction system disclosed in Patent Document 1 below. (Referred to as “input amount determination device”) solves this problem as follows.
Input request after adding the required steam input (boiler master signal) and required steam volume (difference between measured main steam pressure and set main steam pressure) in boiler control as an index to measure the combustion state of the boiler This ratio is stored in the system sequentially, the fuel correction coefficient is obtained from multiple values of the stored ratio, and the required steam quantity is corrected with the calculated fuel correction coefficient. Thus, an appropriate fuel input amount is determined according to the combustion state of the boiler.

Japanese Patent No. 4522326

  However, the above-described conventional boiler fuel input amount determination device is designed so that the ratio of the required input steam amount to the required steam amount is always maintained at the target ratio. The ratio target is maintained by compensating for the ratio target, but this ratio target is fixed with the same parameters after being determined and entered during the trial run. Therefore, the state where it is difficult to set the main steam pressure of the boiler is kept with the fuel correction coefficient. Also, fluctuations in the main steam pressure are fed back and added to the required steam volume, and the ratio itself is likely to fluctuate, making it difficult to maintain the ratio target with the fuel correction factor, and suppressing the disturbance by the boiler fuel reduction system It has an effect on the effect and fuel reduction effect.

For this reason, it is desirable to always verify that the ratio target set in the boiler fuel reduction system is optimal so that the ratio target can be automatically changed. It was difficult to put it into practical use.
(1) Evaluation method for determining whether the current ratio target is optimal (2) Method for automatically changing the ratio target based on the evaluation

  An object of the present invention is to provide a boiler fuel input amount determination device that can automatically change a ratio target by verifying whether the ratio target set in the boiler fuel reduction system is optimal.

The boiler fuel input amount determination device of the present invention determines the fuel input amount (Fueli) to be supplied to the boiler from the input required steam amount (A), supplies fuel to the boiler corresponding to the determined fuel input amount, Measuring the main steam pressure (Pi) generated in the boiler, obtaining a feedback correction amount from the measured main steam pressure and the set main steam pressure, and correcting the fuel injection amount with the feedback correction amount A ratio determining means (13) for determining a ratio (Ki) between the input required steam amount and the required steam amount (B) of the boiler after feedback correction by the feedback correction amount; The ratio obtained by the ratio calculating means is sequentially stored in a memory, and the coefficient average value is obtained by moving average including the past ratio stored in the memory, and the obtained coefficient average value is the vapor pressure. If it is within an allowable range determined according to the magnitude of the deviation or if the stable time of the required steam amount does not last for a predetermined time, the existing coefficient average value in the memory is not updated, When the obtained coefficient average value deviates from the allowable range and the stable time of the required steam amount continues for a predetermined time, the existing coefficient average value is multiplied by the obtained coefficient average value to multiply the existing coefficient average value. The fuel correction for obtaining the fuel correction coefficient (Kipgε) corresponding to the current required steam amount by interpolating the updated coefficient average value with the required steam amount Coefficient calculating means (15, 16), fuel input amount correcting means (19) for correcting the fuel input amount with the fuel correction coefficient obtained by the fuel correction coefficient calculating means, and the ratio for each update time Day of Data number distribution confirmation / standard deviation evaluation means (34, 35 _{1 to} 35 ₅ , 36 for evaluating the fuel input amount or the main steam pressure with a standard deviation at each update time. _{1 to} 36 ₅ , 37, 38) and the evaluation result by the data number distribution confirmation / standard deviation evaluation means determine whether the ratio target set in the boiler fuel reduction system is optimal, and the ratio target is optimal If not, a correction ratio (Goiii) for changing the ratio target is determined, and a state determination means (39) for inputting the determined correction ratio to the fuel correction coefficient calculation means instead of the ratio; It is characterized by comprising.
Here, the data number distribution confirmation / standard deviation evaluation means confirms whether the number of data of the ratio changes centering on the ratio target, and the number of data of the ratio changes centering on the ratio target. If not, the control at the ratio target may be determined to be defective.
If the data number distribution confirmation / standard deviation evaluation means determines that the control at the ratio target is poor, the fuel injection amount or the main deviation of the main steam pressure for each predetermined number of bands of the ratio may be calculated. .
When the data number distribution confirmation / standard deviation evaluation means does not reach the predetermined number of data, the evaluation based on the standard deviation may not be performed.

The boiler fuel input amount determination device of the present invention has the following effects.
(1) The ratio target can be automatically changed when the ratio target set in the boiler fuel reduction system is not optimal.
(2) Improvement of the fuel reduction rate of the boiler fuel reduction system, reduction of fluctuations in the main steam pressure of the boiler, enhancement of the disturbance suppression function, stabilization of the furnace temperature by improvement of the combustion state in the furnace, and shortening of the trial operation period when the system is introduced be able to.
(3) As a secondary effect, improvement of thermal shock to the boiler body and reduction of exhaust CO ₂ can be achieved.

It is a block diagram which shows the structure of the boiler fuel injection amount determination apparatus by one Example of this invention. FIG. 2 is a block diagram illustrating a configuration of an automatic gain update unit 30 illustrated in FIG. 1. 3 is a flowchart for explaining the operation of the boiler fuel input amount determination device when the automatic gain update unit 30 shown in FIG. 1 is operated. It is a figure for demonstrating the specific operation example of the automatic gain update part 30 shown in FIG.

  For the above purpose, it is set in the boiler fuel reduction system by checking the distribution of the number of data of the ratio of input required steam volume and required steam volume at each update time and evaluating the fuel input amount or main steam pressure with standard deviation. The ratio target is determined to be optimal, and if the ratio target is determined not to be optimal, the ratio target is changed.

Hereinafter, an embodiment of a boiler fuel input amount determination device of the present invention will be described with reference to the drawings.
The boiler fuel input amount determination device according to the present invention is an evaluation method for evaluating the control state of a conventional boiler fuel reduction system so as not to affect the existing control. The evaluation result is obtained by adopting two steps of a first step for confirming the distribution of the number of data of the ratio to the amount and a second step for evaluating the fuel input amount or the main steam pressure by the standard deviation at each update time. Is used to determine whether the ratio target of the boiler fuel reduction system is optimal, and when it is determined that the ratio target is not optimal, the ratio target is automatically changed.
Here, the first step is a step for confirming whether or not the number of data of the ratio between the input required steam amount and the required steam amount is changing around the ratio target, and the boiler fuel reduction system operates with the optimum ratio target. If so, the number of data of this ratio is distributed around the ratio target. If this is not the case, the control at the ratio target is determined to be defective, and the process proceeds to the second step.
In the second step, it is possible to select either the fuel input amount or main steam pressure at which process controllability is likely to appear, and the selected fuel input amount or main steam pressure data is aggregated at each update time, and an input request is made. A standard deviation of the fuel input amount or main steam pressure for each predetermined number of bands of the ratio of the steam amount to the required steam amount is calculated. The standard deviation represents a discrete distribution from the average value, and it can be said that the smaller the standard deviation, the smaller the fluctuation of the process and the better the controllability. However, since the calculation of standard deviation with a small number of data for the ratio of required input steam volume to required steam volume is not reliable, the number of data for the ratio of required input steam volume to required steam volume is the specified data. If the number is not reached, the standard deviation should not be compared.

Therefore, the boiler fuel input amount determining apparatus according to one embodiment of the present invention includes a main steam pressure transmitter P, a PID control unit 11, an adding unit 12, a dividing unit 13, and a first order lag as shown in FIG. Correction unit 14, moving average calculation unit 15, program calculation unit (PRG calculation unit) 16, change rate limiting unit 17, switch 18, multiplication unit 19, fuel input amount calculation unit 20, automatic gain update A unit 30, a selection unit 51, and a switch 52 are provided.
That is, the boiler fuel input amount determination device according to the present embodiment is different from the conventional boiler fuel input amount determination device in that it includes an automatic gain update unit 30, a selection unit 51, and a switch 52.

As shown in FIG. 2, the automatic gain update unit 30 includes a first-order lag correction unit 31, a switch 32, first and second moving average calculation units 33 ₁ and 33 ₂ , a data distribution unit 34, and a first to an index counter 35 _{1-35 5} of the fifth, and the standard deviation data storage unit 36 ₁ to 36 ₅ of the first to fifth, a data waveform counting unit 37, a standard deviation calculation unit 38, the state determination program unit ( (State determination PRG section) 39, an adder 40, and a switch 41.

First, the operation of the boiler fuel input amount determining device when the automatic gain updating unit 30 is not operated (that is, the operation of the conventional boiler fuel input amount determining device) will be described.
When the automatic gain update unit 30 is not operated, the switch 52 is switched to select constant = 1, and the selection unit 51 selects the ratio Ki input from the division unit 13.

  At all times, in order to output the required amount of power generated by the generator, the boiler operation unit inputs the boiler required steam volume (input required steam volume A) corresponding to the generator output, and inputs the fuel function F1. The fuel input amount calculation unit 20 determines the fuel input amount Fueli to be supplied to the boiler based on the required steam input A to the boiler and the set fuel function F1, and the determined fuel input amount Fueli is supplied to the boiler. The

  The main steam pressure Pi (pressure of steam generated in the boiler) is measured by a pressure gauge or the like provided in the boiler, and the measured main steam pressure Pi is input to the main steam pressure transmitter P. Based on the main steam pressure Pi input to the main steam pressure transmitter P, the main steam pressure correction operation amount is set by the PID control unit 11.

For example, there is almost no pressure difference between the set value and the actual operating value if the fuel function F1 is obtained under conditions that maintain boiler conditions (such as dirt on the heat transfer surface), fuel properties, and other factors. The required generator output can be obtained from the fuel function F1, but the pressure difference between the main steam pressure Pi and the set main steam pressure (hereinafter referred to as `` feedback correction '') due to the boiler state change, fuel properties and other factors change of the boiler Also referred to as “amount”).
Therefore, when the PID control unit 11 detects that a pressure difference has occurred between the main steam pressure Pi and the set main steam pressure, the addition unit 12 calculates a deviation (error amount) of the main steam pressure Pi generated due to excess or shortage of fuel. After adding to the input required steam amount A, the division unit 13 calculates the ratio Ki (coefficient reference value) between the input required steam amount A (= MWi) before pressure correction and the required steam amount B (= MWii) after pressure correction. calculate.
Ki = MWii / MWi (1)

  The primary delay correction unit 14 corrects the ratio Ki to the primary delay in order to suppress transient fluctuations (hunting) due to the primary delay of 10 seconds. Thereby, the noise contained in the ratio Ki can be cut, and the accuracy of the ratio Kil after correction of the first-order lag (coefficient reference value after the first-order lag correction) can be improved.

The moving average calculation unit 15 calculates the ratio moving average value Kiε (coefficient average value) by moving average the ratio Kil after the first-order delay correction for 30 seconds.
Here, the moving average calculation unit 15 sequentially stores the ratio Kil after the first-order lag correction in a built-in memory, and performs a moving average including the ratio Kil after the first-order lag correction stored in the memory to obtain a coefficient average. Find the value.

The program calculation unit 16 uses the ratio moving average value Kiε calculated by the moving average calculation unit 15 and the obtained ratio moving average value Kiε is within an allowable range determined according to the magnitude of the steam pressure deviation. Alternatively, if the stable time of the required steam amount B does not continue for a predetermined time (for example, 5 minutes), the ratio Kil after the correction of the existing first-order delay in the memory of the moving average calculation unit 15 is not updated, but is obtained. When the ratio moving average value Kiε deviates from the allowable range and the stable time of the required steam amount B continues for a predetermined time, the ratio Kil after the correction of the first-order lag correction is multiplied by the ratio moving average value Kiε. The existing ratio Kil after the first-order lag correction is updated and stored in the memory of the moving average calculation unit 15, and the updated first-order lag corrected ratio Kil is interpolated by the required steam quantity B to obtain the current required steam quantity B. Fuel correction factor according to Kipg Calculating the (proper correction value Kipg the previous stage of the fuel correction coefficient).
In addition, about the program calculating part 16, the reset of a coefficient and the setting of a calculation start are also possible (a coefficient reset trigger and a calculation start trigger).

The rate-of-change limiting unit 17 provides a rate-of-change limitation (for example, 0.02 / min) for the appropriate correction value Kipg calculated by the program calculating unit 16 in consideration of a rapid change in the operation state of the boiler. Thus, the fuel correction coefficient Kipgε is obtained.
At the time of system abnormality (error) and initialization (initial setting), the switch 18 is switched to use constant = 1 instead of the fuel correction coefficient Kipgε.

The multiplying unit 19 multiplies the fuel input amount Fueli obtained from the fuel function F1 and the required steam amount B by the fuel input amount calculating unit 20 by the fuel correction coefficient Kipgε to obtain an appropriate fuel corresponding to the required main steam pressure Pi. An input amount (that is, a corrected fuel input amount Fuelii) is obtained.
Fuelii ＝ Kipgε × Fueli （２）
When constant = 1 is used instead of the calculated fuel correction coefficient Kipgε, the fuel input amount Fueli obtained from the fuel function F1 and the required steam amount B is output to the boiler as the corrected fuel input amount Fuelii. Is done.
Fuelii = 1 x Fueli = Fueli (3)
By supplying fuel to the boiler by this corrected fuel input amount Fuelii, the necessary main steam pressure Pi is obtained to obtain the power generation amount. It should be noted that after the fuel of the corrected fuel injection amount Fuelii obtained is input to the boiler, the main steam pressure Pi of the boiler is measured, and the above-described procedure is repeated based on the measured main steam pressure Pi.

Next, the operation of the boiler fuel input amount determination device when the automatic gain update unit 30 is operated will be described with reference to FIGS. 2 and 3.
When the automatic gain updating unit 30 is operated, the switch 52 is switched to select the correction ratio Goiii, and the selection unit 51 selects the correction ratio Goiii input from the switch 52.

Similar to the primary delay correction unit 14 shown in FIG. 1, the primary delay correction unit 31 corrects the ratio Ki input from the division unit 13 in order to suppress transient fluctuation (hunting) due to the primary delay for 10 seconds. To do.
In the following, in order to distinguish from the ratio Kil after the first-order lag correction output from the first-order lag correction unit 14 shown in FIG. 1, the ratio after the first-order lag correction output from the first-order lag correction unit 31 is the first-order lag. This is referred to as a post-correction ratio Gi (coefficient reference value after primary delay correction).

The first moving average calculating unit 33 ₁ operates in the same manner as the moving average calculation section 15 shown in FIG. 1, the set moving average time (e.g., moving average in the moving average calculation section 15 shown in FIG. 1 The ratio Gi after the first-order lag correction Gi is calculated as a moving average value Gii.
Hereinafter, the ratio moving average value Gii is referred to as “ratio Gii”.

  The switch 32 selects one of the fuel input amount Fueli input from the fuel input amount calculation unit 20 shown in FIG. 1 and the main steam pressure Pi input from the main steam pressure transmitter P shown in FIG. .

Similarly to the _first moving average calculation unit 33 ₁ , the _second moving average calculation unit 33 ₂ performs a moving average of the fuel input amount Fueli or the main steam pressure Pi selected by the switch 32 for the set moving average time. Then, the fuel input amount moving average value or the main steam pressure moving average value is calculated.
In the following, a fuel input amount moving average or main steam pressure moving average value output from the second moving average calculating section _332, since the data for calculating the standard deviation in the standard deviation calculating section 38 , Referred to as “standard deviation data D”.

Data sorting unit 34, the ratio data of the first to fifth band in accordance with ratios Gii inputted from the first moving average calculating unit 33 ₁ of its size (hereinafter, "first to fifth ratio data It distributes the G ₁ ~G ₅ "and referred.), is counted each the number of data of the first to fifth ratio data G ₁ ~G ₅ an index counter 35 _{1-35 5} of the first to fifth.
For example, if 1.015 <ratio Gii (within the first band), the data distribution unit 34 distributes the ratio Gii to the first ratio data G ₁ and sets the count number of the first index counter 35 ₁ to 1. When it is increased by 1.005 <ratio Gii ≦ 1.015 (within the second band), this ratio Gii is distributed to the second ratio data G ₂ and the count number of the _second index counter 35 ₂ is set. When it is incremented by one and 0.995 <ratio Gii ≦ 1.005 (within the third band), this ratio Gii is distributed to the third ratio data G ₃ and the count number of the _third index counter 35 ₃ Is incremented by one, and if 0.985 <ratio Gii ≦ 0.995 (within the fourth band), this ratio Gii is distributed to the fourth ratio data G ₄ and the count of the _fourth index counter 354 Increase the number by one, Rate Gii ≦ 0.985 increase the count number of the fifth index counter 35 ₅ of one with distributing (fifth in-band) Within this ratio Gii to the fifth ratio data G _5.

The first to fifth index counters 35 _{1 to} 35 ₅ increase the second moving average calculation unit 33 _{2 with} respect to the _{first to fifth} standard deviation data storage units 36 _{1 to} 365 whenever the count number is increased. and outputs the first to the data acquisition command of the fifth to instruct to store the standard deviation data D inputted to the first to fifth standard deviation data storage unit 36 ₁ to 36 ₅ from.
In the following description, it referred to the standard deviation data D stored in the standard deviation data storage unit 36 ₁ to 36 ₅ of the first to fifth "standard deviation of the first to fifth data D ₁ to D _5".

The data waveform totaling unit 37 takes in the count numbers of the first to _fifth index counters 35 _{1 to} 35 ₅ every set update time (for example, 10 hours), and the first to fifth ratio data G _1. perform a number of data aggregation work of ~G _5.

The standard deviation calculation unit 38 first to fifth standard deviation data D stored in the first to _fifth standard deviation data storage units 36 _{1 to} 365 for every set update time (for example, 10 hours). _{1 to} D ₅ are taken in, and first to fifth standard deviations σ _{1 to} σ ₅ are calculated using equation (4).
σ _i = [{nΣD _i ² − (ΣD _i ) ² } / n ² ] ^1/2 (4)
Where i = 1-5
n = number of samples (total number of _{first to fifth} standard deviation data D _{1 to} D ₅ )

The state determination unit 39 counts the number of data of the _{first to fifth} ratio data G _{1 to} G ₅ input from the data waveform totaling unit 37 and the first to _fifth data input from the standard deviation calculation unit 38. based on the standard deviation σ ₁ ~σ _5, to determine whether the optimal target ratio set in the boiler fuel reduction system, the ratio target is determined not to be optimal, the ratio correction value Goi as follows To calculate.

When the gain calculation command is turned on (step S11 in FIG. 3), the state determination unit 39 sets the number of data of the third ratio data G ₃ (ratio Gii where 0.995 <ratio Gii ≦ 1.005) = It is determined whether or not the value obtained by dividing CNT_DATA3 by the number of samples = CNT_TOTAL (= n) is equal to or greater than the first band setting value BAND1_SET = 0.65 (step S12).
Here, the first band setting value BAND1_SET is a band setting value for maintaining the ratio target with respect to the current ratio target. In general, in the standard normal distribution, the average value ± 1σ (standard deviation) is centered on the average value. the number of data to be included within the scope of) since the 68.26% of the total number of data, CNT_DATA3 / CNT_TOTAL ≧ generally centered above the normal distribution in the case of the 0.65 third ratio data G ₃ is densely Since it can be determined that the control is centered on the ratio target, 0.65 (= 1σ) is set as the first band setting value BAND1_SET.

  If the determination result in step S12 is “YES”, the state determination unit 39 determines that the control is centered on the ratio target, returns to step S12, and performs the same operation for the next update time. repeat.

On the other hand, when the determination result of step S12 is “NO”, the state determination unit 39 counts the number of data of the second ratio data G ₂ (ratio Gii where 1.005 <ratio Gii ≦ 1.015) = Value obtained by dividing the sum of CNT_DATA2 and the fourth ratio data G ₄ (ratio Gii where 0.985 <ratio Gii ≦ 0.995) = CNT_DATA4 (= CNT_DATA2 + CNT_DATA4) by the number of samples = CNT_TOTAL (= n) Is greater than or equal to the second band set value BAND2_SET = 0.35 (step S13).
Here, the second band setting value BAND2_SET is a band setting value for confirming the ratio transition with respect to the current ratio target. Generally, in the standard normal distribution, the average value is within the range of ± 2σ around the average value. Therefore, the number of data included in the range of the average value ± 1σ and the average value ± 2σ is 27.18% (= 95). .44% -68.26%), so even if the controllability deteriorates and the peak of the mountain shifts, there is 35% or more of data within the range of the average value ± 2σ. In this case, a more stable settling point can be calculated by comparing the standard deviation of the fuel input amount Fueli or the main steam pressure Pi on both sides, so the second band set value BAND2_SET 0.35 (= 2σ) is set.

When the determination result of step S13 is “NO”, the state determination unit 39 determines the number of data of the first ratio data G ₁ (1.015 <the ratio Gii where the ratio Gii is equal) = CNT_DATA1 and the fifth ratio. It is determined whether the number of data G ₅ (the ratio Gii where the ratio Gii ≦ 0.985) = CNT_DATA5 is equal to or greater than the first data number setting value A1 (step S14).
On the other hand, when the determination result in step S13 is “YES”, the state determination unit 39 counts the number of data of the second ratio data G ₂ (ratio Gii where 1.005 <ratio Gii ≦ 1.015) = It is determined whether the number of data of CNT_DATA2 and the fourth ratio data G ₄ (ratio Gii where 0.985 <ratio Gii ≦ 0.995) = CNT_DATA4 are both equal to or greater than the second data number setting value A2 ( Step S15).
Here, since the first and second data number set values A1 and A2 are not reliable in order to calculate the standard deviation of the fuel input amount Fueli and the main steam pressure Pi, the reliability is poor. Since this is for confirming whether the number of data is secured in the stage before comparison of standard deviations in steps S16 and S17 described later, for example, 10% of the number of samples = CNT_TOTAL (= n) (= 0) .1 × n).

If the determination result in step S14 is “YES”, the state determination unit 39 determines whether or not the fifth standard deviation σ ₅ is equal to or greater than the first standard deviation σ ₁ (step S16).
When the determination result in step S15 is “YES”, the state determination unit 39 determines whether or not the second standard deviation σ ₂ is equal to or greater than the fourth standard deviation σ ₄ (step S17). ).
On the other hand, if the determination results in steps S14 and S15 are “NO”, the state determination unit 39 returns to step S12 and repeats the same operation for the next update time.

If the determination result in step S16 is “YES” or the determination result in step S17 is “NO”, the state determination unit 39 sets the ratio correction value Goi = 0.002 (step S18), and then proceeds to step S12. Return and repeat the same operation for the next update time.
On the other hand, when the determination result of step S16 is “NO” or the determination result of step S17 is “YES”, the state determination unit 39 sets the ratio correction value Goi = −0.002 (step S19). Returning to step S12, the same operation is repeated for the next update time.
Here, the ratio correction value Goi is set to 0.002 or -0.002 in order to change the ratio target while changing the correction ratio Goiii in small increments and confirming the control validity, but other values may be used. Good.

The adding unit 40 adds the ratio correction value Goi input from the state determination unit 39 and the previous correction ratio Goii (previous value) or constant = 1 selected by the switch 41 to generate a new correction ratio Goiii.
Here, when the automatic gain update unit 30 is not operating, the constant = 1 is selected by the switch 41.

Next, a specific operation example of the automatic gain updating unit 30 will be described with reference to FIGS.
The previous correction ratio Goii = 1.

When CNT_DATA1 = 720, CNT_DATA2 = 1800, CNT_DATA3 = 28080, CNT_DATA4 = 3600, CNT_DATA5 = 1800 and CNT_TOTAL = 36000 (= 720 + 1800 + 28080 + 3600 + 1800) as shown in FIG. 4A, CNT_DATA3 / CNT_TOTAL = 28080/36000 = Since 0.78 ≧ 0.65, the determination result in step S12 shown in FIG. 3 is “YES”.
As a result, the state determination unit 39 determines that the control is centered on the ratio target, returns to step S12, and repeats the same operation for the next update time.
Therefore, in this case, the correction ratio Goiii remains the previous correction ratio Goii = 1.

As shown in FIG. 4B, CNT_DATA1 = 2520, CNT_DATA2 = 8280, CNT_DATA3 = 12600, CNT_DATA4 = 9000, CNT_DATA5 = 3600, and CNT_TOTAL = 36000 (= 2520 + 8280 + 12600 + 9000 + 3600), σ ₁ = 0.03, σ ₂ = 0 .02, σ ₄ = 0.022, and σ ₅ = 0.03, CNT_DATA3 / CNT_TOTAL = 1260/36000 = 0.35 <0.65, so the determination in step S12 shown in FIG. The result is “NO”.
Since (CNT_DATA2 + CNT_DATA4) / CNT_TOTAL = (8280 + 9000) /36000=1780/36000=0.48≧0.35, the determination result in step S13 shown in FIG. 3 is “YES”.
Further, since CNT_DATA2 = 8280 ≧ 3600 (= A2 = 0.1 × 36000) and CNT_DATA4 = 9000 ≧ 3600 (= A2 = 0.1 × 36000), the determination result in step S15 shown in FIG. Becomes “YES”.
Furthermore, since σ ₂ (= 0.02) <σ ₄ (= 0.022), the determination result in step S17 shown in FIG. 3 is “NO”.
As a result, the state determination unit 39 sets the ratio correction value Goi = 0.002 (see step S18 shown in FIG. 3).
Thereby, since the previous correction ratio Goii = 1, the correction ratio Goiii = Goii + Goi = 1 + 0.002 = 1.002 is set in the adding unit 40, and the boiler fuel is set so that the ratio target becomes the correction ratio Goiii = 1.002. The reduction system can be operated.

P main steam pressure transmitter 11 PID control unit 12 addition unit 13 division unit 14 primary delay correction unit 15 moving average calculation unit 16 program calculation unit 17 change rate limiting unit 18, 52 switch 19, 51 multiplication unit 20 fuel input amount calculation unit 30 Automatic gain update unit 31 First-order lag correction unit 32, 41, 51 Switch 33 ₁ , 33 ₂ First and second moving average calculation unit 34 Data distribution unit 35 _{1 to} 35 ₅ First to fifth index counters 36 ₁ ~ 36 ₅ 1st to 5th standard deviation data storage part 37 Data waveform totaling part 38 Standard deviation calculation part 39 State determination program part 40 Adder 52 Selection part S11-S19 Step

Claims (4)

The fuel input amount (Fueli) supplied to the boiler is obtained from the input required steam amount (A), the fuel is supplied to the boiler corresponding to the obtained fuel input amount, and the main steam pressure (Pi) generated in the boiler A boiler fuel injection amount determination device for determining a feedback correction amount from the measured main steam pressure and the set main steam pressure, and correcting the fuel injection amount by the feedback correction amount,
Ratio calculating means (13) for determining a ratio (Ki) between the input required steam amount and the required steam amount (B) of the boiler after feedback correction by the feedback correction amount;
The ratio obtained by the ratio calculating means is sequentially stored in a memory, and a moving average including a past ratio stored in the memory is obtained to obtain a coefficient average value. The obtained coefficient average value is a value of the steam pressure deviation. If the required amount of steam is within a predetermined allowable range depending on the size, or if the stable time of the required steam amount does not last for a predetermined time, the existing coefficient average value in the memory is not updated, while the obtained When the coefficient average value deviates from the allowable range and the stable time of the required steam amount continues for a predetermined time, the existing coefficient average value is multiplied by the obtained coefficient average value to multiply the existing coefficient Fuel correction coefficient calculation for obtaining a fuel correction coefficient (Kipgε) according to the current required steam amount by interpolating the updated coefficient average value with the required steam amount while updating the average value in the memory Means (1 , And 16),
Fuel injection amount correction means (19) for correcting the fuel injection amount with the fuel correction coefficient obtained by the fuel correction coefficient calculation means;
A data number distribution confirmation / standard deviation evaluation means (34, for evaluating the distribution of the number of data of the ratio at each update time and evaluating the fuel input amount or the main steam pressure by the standard deviation at each update time. 35 _{1-35 5,} 36 _{1-36 5,} 37 and 38),
It is determined whether the ratio target set in the boiler fuel reduction system is optimal based on the evaluation result by the data number distribution confirmation / standard deviation evaluation means, and if the ratio target is determined not optimal, the ratio target is changed. A state determining means (39) for determining a correction ratio (Goiii) of the input and inputting the determined correction ratio to the fuel correction coefficient calculating means instead of the ratio;
A boiler fuel input amount determination device comprising:   The data number distribution confirmation / standard deviation evaluation means confirms whether the number of data of the ratio changes centering on the ratio target, and when the number of data of the ratio does not change centering on the ratio target 2. The boiler fuel injection amount determining apparatus according to claim 1, wherein the control at the ratio target is determined to be defective.   When the data number distribution confirmation / standard deviation evaluation means determines that the control in the ratio target is poor, the fuel injection amount or the standard deviation of the main steam pressure for each predetermined number of bands of the ratio is calculated. The boiler fuel input amount determination device according to claim 2.   4. The boiler fuel injection according to claim 3, wherein the data number distribution confirmation / standard deviation evaluation means does not perform evaluation based on the standard deviation when the number of data of the ratio does not reach a predetermined number of data. Quantity determination device.

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