KR20180056303A - Pressure model predicting apparatus for boiler of power plant - Google Patents

Abstract

The boiler pressure model estimating apparatus of a power plant includes a boiler master step response test trend data generating unit for storing boiler master step response test trend data generated through a boiler master step response test of a power plant in a picture file form, And an average delay time and an average time constant for the generator output signal and the main steam pressure signal for the step input of the boiler master are estimated from the extracted signals, The time-lapse and delay time estimating means and the first-order process model including the time constant (T) and the delay time (Td) estimated from the boiler master step response test trend data are approximated to the n-th order first- A boiler pressure model approximation unit, and an approximated n-th order primary process Calculating the order n and time constant Del to include parts of the boiler pressure applied to the model applied in the main steam pressure setting model of a power plant main control loop.

Description

[0001] PRESSURE MODEL PREDICTING APPARATUS FOR BOILER OF POWER PLANT [0002]

The present invention relates to an apparatus for estimating a boiler pressure model of a power plant, and more particularly, to a system and method for estimating a boiler pressure model of a power plant by storing a trend of a boiler master step response test as a drawing file, And extracting a time signal and a delay time from the extracted data to estimate a boiler pressure setting model.

Generally, most of the power plants in Korea prevent deterioration of the control performance against the process change of the plant after the planned preventive maintenance, and the main control parameters of the plant (eg, generator output, main steam pressure, main steam temperature, reheat steam temperature Etc.) to control loops.

At this time, the controller tuning for the main control loop of the power plant is performed by observing the change of the main control parameters through the load swing test and the step response test for the boiler master signal controlling the boiler control The response of the output side when the level is changed in a stepwise manner), and the result of model estimation is reflected in the control logic.

At this time, the boiler master signal is determined according to the generator output set value, and is corrected by the output value of the boiler pressure controller or the like.

That is, when the set value of the generator output is inputted, the boiler master signal corresponding to the fuel amount corresponding to the generator output is generated, and the controller output for the deviation of the set value of the boiler pressure is added to the signal to serve as the boiler master signal.

On the other hand, it takes time for the boiler master signal to operate and the boiler pressure to change due to the change of the fuel amount due to the boiler master signal. Therefore, if the set value is changed before the actual main steam pressure is generated, a main steam pressure error occurs and the boiler master (i.e., the top controller that controls the amount of fuel, the amount of air, and the amount of water related to the operation of the boiler) The main steam pressure controller that contributes to the boiler master signal needs to operate at the point where the main steam pressure fluctuates.

That is, sufficient time is required before the main steam pressure is generated, and when the pressure starts to be generated, the main steam pressure set value corresponding to the generator output set value is changed so that the actual main steam pressure needs to follow the set value.

Therefore, in order to improve the control performance of the main steam pressure, a boiler pressure model (or a boiler pressure setting model) (that is, an input (for example, a fuel ), The boiler pressure does not change in real time but takes into account the change with time constant and time delay, and a model which approximates the process of actual pressure change with respect to the input) is applied.

For reference, the boiler pressure model (or the boiler pressure setting model) is calculated by subtracting the main steam pressure for the step input of the boiler master from the trend of the boiler master step response test (i.e., the change in the boiler response data with respect to the graphically expressed time) The output response is estimated with a first-order process model having a time delay, and then the process model having the estimated time-number and the time delay is approximated to n first-order process models without time delay and utilized. This is the process of approximating the first-order process model with delay time to the process model with only the nth order time constant since there is no tuning function for the function block for the time delay in the control system and it is difficult to implement.

However, in estimating the time constant and the delay time as the boiler characteristics from the above-mentioned boiler master step response, it is conventionally known that the time constant (in other words, the change in the boiler response data with respect to the graphically expressed time) And delay time. Therefore, even if the same trend is used, there is a problem that the estimation result of the time constant and the delay time differs depending on the user, and the consistency of the boiler pressure model (or the boiler pressure setting model) is poor.

The background of the present invention is disclosed in Korean Patent Laid-Open Publication No. 10-2013-0117661 (published Oct. 29, 2018, a method and apparatus for determining model parameters for controlling a steam power plant, a control unit for a steam generator, and a computer program product) have.

According to an aspect of the present invention, there is provided a method of controlling a boiler master step response test, comprising the steps of: storing a trend of a boiler master step response test as a drawing file; The present invention provides an apparatus for estimating a boiler pressure model of a power plant that extracts an output signal and a main steam pressure signal and extracts a time constant and a delay time from the extracted data to consistently estimate a boiler pressure setting model.

The apparatus for estimating a boiler pressure model of a power plant according to an aspect of the present invention includes a boiler master step response test test data generation unit for storing boiler master step response test data generated in response to a boiler master step response test of a power plant, ; A vision processor for reading image information input in the form of a picture file and extracting each signal included therein; A time constant and a delay time estimator for estimating an average time constant and an average delay time for the generator output signal and the main steam pressure signal from the extracted signal to the step input of the boiler master; A boiler pressure model approximation unit for approximating a first process model including a time constant (T) and a delay time (Td) estimated from the boiler master step response test trend data to an nth order process model without time delay; And a boiler pressure model application unit for calculating the order n and the time constant in the approximated n-th order primary process model and applying it as a main steam pressure setting model of the main control loop of the power plant.

According to one aspect of the present invention, the present invention extracts a boiler master signal, a generator output signal, and a main steam pressure signal using a picture file of a trend of a boiler master step response test, extracts a time constant and a delay time from the extracted data, This makes it possible to provide consistency in the calculation of the tuning data of the main control loop of the power plant, without any computational errors, and to be utilized even if not a control expert, to enhance the utilization of the boiler pressure model tuning.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing an apparatus for estimating a boiler pressure model of a power plant according to an embodiment of the present invention; FIG.
Figure 2 is an exemplary diagram illustrating the load response test and the boiler master step response test.
3 is an exemplary diagram showing a step response characteristic graph of n first-order process models without time delay according to an embodiment of the present invention;
FIG. 4 is a diagram illustrating a method of estimating a time constant and a time delay in a boiler master step response test according to an embodiment of the present invention; FIG.
5 and 6 are diagrams illustrating an example of a step-up and step-down test trend according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a boiler pressure model estimating apparatus according to the present invention will be described with reference to the accompanying drawings.

In this process, the thicknesses of the lines and the sizes of the components shown in the drawings may be exaggerated for clarity and convenience of explanation. In addition, the terms described below are defined in consideration of the functions of the present invention, which may vary depending on the intention or custom of the user, the operator. Therefore, definitions of these terms should be made based on the contents throughout this specification.

FIG. 1 is a schematic view illustrating an apparatus for estimating a boiler pressure model of a power plant according to an embodiment of the present invention. Referring to FIG.

1, the apparatus for estimating a boiler pressure model (or a boiler pressure setting model) of a power plant according to the present embodiment includes a boiler master step response test trend data generation unit 110, a vision processing unit 120, A delay time estimating unit 130, a boiler pressure model approximating unit 140, and a boiler pressure model applying unit 150.

The boiler master step response test trend data generation unit 110 uses the trend test function of the field console to generate a trend signal indicating the main steam pressure signal of the boiler master signal (a kind of power plant boiler control signal), the generator output signal, , The change in the boiler response data with respect to the graphically expressed time), and the boiler master (not shown) is stepped up (for example, by stepping up the output of the boiler at a specified step rate Perform the master step response test.

The boiler master step response test trend data generation unit 110 stores the boiler master step response test trend data in an internal storage (not shown) in the form of a picture file (or an image file).

For reference, FIG. 2 is an example for explaining the load reaction test and the boiler master step response test. In most domestic power plants, the control performance against the process change of the power plant after the planned preventive maintenance is prevented, Controller tuning for major control loops (eg, generator output, main steam pressure, main steam temperature, reheat steam temperature, etc.).

At this time, the controller tuning for the main control loop of the power plant is performed by observing the change of the main control parameters through the load swing test and the step response test for the boiler master signal controlling the boiler control The response of the output side when the level is changed in a stepwise manner), and the result of model estimation is reflected in the control logic.

When the boiler master step response test trend data is generated in the form of a picture file (or an image file) as described above, the vision processor 120 performs vision processing on the boiler master step response test trend data to generate a boiler master signal, (Or identifies) the time signal on the horizontal axis and the signal range for each signal on the vertical axis for the main steam pressure signal. That is, in the present embodiment, the vision processor 120 reads image information (a graph of each signal in this embodiment) input in a file form and extracts (or identifies) each signal included therein.

5 and 6 are diagrams illustrating an example of a step-up and step-down test trend according to an embodiment of the present invention. As shown in FIG. 5, the boiler master signal (a kind of control signal) Boiler Master Demand) can be identified step by step (or step), and the generator output signal (BLR Actual Load) and main steam pressure signal (Main Steam Press) can be extracted Do.

In addition, in order to facilitate the vision processing in the vision processor 120, it is also possible to provide information on the manufacturer (for example, functions of the trend, the appearance, characteristics, and the like) And a time range may be further provided to facilitate data extraction.

The time constant and delay time estimator 130 estimates the generator output and the main steam pressure signal as a first process model having a time delay with respect to the step input of the boiler master from the extracted signal, The time constant and delay time of the generator output response and the time constant and delay time of the main steam pressure signal response to the boiler master step input are calculated.

The time constant and the delay time for the first signal are set to be T (t) and T (t), respectively, irrespective of whether the generator output signal or the main steam pressure signal is difficult to be extracted _{C1_UP} and T _{D1_UP} , and _assuming that the time constant and the delay time for the second signal are T _{C2_UP} and T _{D2_UP} , respectively, the time constant and the delay time for each signal are represented by the maximum rate of change of the step response curve shown in FIG. Can be estimated by using the tangent line of FIG.

Also, the boiler master step response test trend data generation unit 110 uses the trend test function of the field console to analyze the trend of the main steam pressure signal of the boiler master signal (a kind of power plant boiler control signal), the generator output signal, (For example, a change in the boiler response data with respect to the time expressed in a graphical manner), and a step down of the boiler master (not shown) (step down of the boiler output with a specified step rate Perform boiler master step response test.

The boiler master step response test trend data generation unit 110 stores trend data as a result of the boiler master step response test in an internal storage device (not shown) in the form of a picture file (or an image file).

When the boiler master step response test trend data is generated in the form of a picture file (or an image file) as described above, the vision processor 120 performs vision processing on the boiler master step response test trend data to generate a boiler master signal, (Or identifies) the time signal on the horizontal axis and the signal range for each signal on the vertical axis for the main steam pressure signal.

For reference, the boiler master signal (a type of control signal) changes stepwise (or stepwise) so that signal identification is possible, and the generator output signal and the main steam pressure signal can be extracted (or identified) in the signal range.

The time constant and delay time estimator 130 estimates the generator output and the main steam pressure signal as a first process model having a time delay with respect to the step input of the boiler master from the extracted signal, The time constant and delay time of the generator output response and the time constant and delay time of the main steam pressure signal response to the boiler master step input are calculated.

The time constant and the delay time for the first signal are set to be T (t) and T (t), respectively, irrespective of whether the generator output signal or the main steam pressure signal is difficult to be extracted _{C1_DN} , and T _{D1_DN} , respectively, and assuming that the time constant and the delay time for the second signal are T _{C2_DN} and T _{D2 _N D} , respectively, the time constant and the delay time for each signal are the maximum rate of change of the step response curve shown in FIG. Can be estimated by using the tangent line of FIG.

Meanwhile, when the time constant and the delay time for the boiler master Step Up and the boiler master Step Down are respectively calculated through the boiler master step response test as described above, the time constant and the delay time estimator 130 calculate the time constant and the delay time the average taken _{(T C = (T C1_UP +} T C2_UP + T C1_DN + T C2_DN) / 4, T D = (T D1_UP + T D2_UP + T D1_DN + T D2_DN) / 4) the average time constant (T _C) and And calculates an average delay time (T _D ).

When the average time constant T _C and the average delay time T _D are calculated as described above, the boiler pressure model approximation unit 140 calculates the average delay time T _D using the average time constant T _C and the average delay time T _D , And estimates the order n and the time constant T by estimating the first-order process model with no time delay (n-th order).

3 is a graph showing a step response characteristic graph of n first-order process models without time delay related to an embodiment of the present invention. As a method for determining the characteristics of a boiler, a step response test The trend data can be used to estimate and characterize the characteristics of the boiler as the first process model.

In this case, the primary process model includes a time constant, a process gain, and a delay time value, and is called a FOPDT (First Order Plus Dead Time) model.

If the Laplace transform of the input u (t), the output y (t), the input u (t) is U (s) and the Laplace transform of the output y (t) is Y (s) The model can be expressed as Equation 1 below, where K is the process gain, T is the time constant, and Td is the delay time.

Since the primary process model estimated as described above can be implemented in the control system and can be tuned, the time constant (T) and the delay time (T) estimated from the boiler master step response test trend data of Equation Td) is approximated to n primary models with no time delay as shown in Equation (2) below. In Equation (2), n denotes the n-th order, and Tc denotes the time constant of the model obtained by approximating the time delay Td and the time constant T of Equation (1) to the first-order model of the n-th order without the time delay.

FIG. 3 is a graph showing the step responses for the n primary models without the time delay.

Here, the larger the order n, the similar to the step response of the first-order process model with time delay. The larger the n value is, the more the first-order filter is required to implement the control logic in the control system. To be approximated three times.

Therefore, the boiler pressure model application unit 150 obtains the time constant by multiplying the taken n by the time constant T and then dividing by 3 (i.e., a generalized number) (time constant = (n * T) / 3) As a parameter of the linear function of the boiler set pressure of the boiler master control logic (not shown) including the pressure model (or boiler pressure model).

4 is a diagram illustrating a method of estimating a time constant and a time delay in a boiler master step response test according to an embodiment of the present invention. Use a tangent line.

At this time, the tangent line at the maximum rate of change has an initial value at the delay time Td and a final value at the time (T + Td).

Accordingly, the time constant and the delay time can be estimated using the tangent line at the maximum change rate point. If the time constant and the delay time are estimated as described above, n first-order models without the time delay of Equation (2) The boiler pressure setting model is used and the tuning is performed.

As described above, the present embodiment extracts the boiler master signal, the generator output signal, and the main steam pressure signal using the trend file, extracts the time constant and the delay time from the extracted data, and calculates the tuning data of the main control loop It is possible to increase the utilization of the boiler pressure model tuning by making it possible to provide consistency, there is no calculation error, and it can be utilized even if it is not a control expert.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, I will understand the point. Accordingly, the technical scope of the present invention should be defined by the following claims.

110: Boiler master step response test trend data generator
120: vision processor
130: time constant and delay time estimating unit
140: Boiler pressure model approximation part
150: Boiler pressure model application part

Claims (4)

Boiler master step response test generated by the plant boiler master step response test boiler master step response test trend data generating part storing trend data in the form of picture file;
A vision processor for reading image information input in the form of a picture file and extracting each signal included therein;
A time constant and a delay time estimator for estimating an average time constant and an average delay time for the generator output signal and the main steam pressure signal from the extracted signal to the step input of the boiler master;
A boiler pressure model approximation unit for approximating a first process model including a time constant (T) and a delay time (Td) estimated from the boiler master step response test trend data to an nth order process model without time delay; And
And a boiler pressure model application unit for calculating the order n and the time constant in the approximated n-th order primary process model and applying it as a main steam pressure setting model of the main control loop of the power plant Device.
2. The image processing apparatus according to claim 1,
Extracts the time signal on the horizontal axis and the signal range for each signal on the vertical axis with respect to the boiler master signal, the generator output signal, and the main steam pressure signal included in the boiler master step response test trend data. Boiler pressure model estimator.
2. The image processing apparatus according to claim 1,
The signal is extracted by further receiving at least one or more of the manufacturer information and the signal color, the signal range, and the time range for the boiler master, the generator output, the main steam pressure, and the time range for easier vision processing. Pressure model estimator.
The apparatus as claimed in claim 1, wherein the time constant and the delay time estimating unit
Through the boiler master step response test, the time constant and the delay time for the boiler master step up and the boiler master step down are calculated, and the average time constant (T _C ) and the average delay time T _D ) of the boiler is calculated.

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