KR101104875B1 - Method and computer-readable recording medium for measuring rod drop time - Google Patents

Abstract

The present invention is to determine the drop time response of the control rod in accordance with the nuclear reactor emergency stop command during the planned preventive maintenance period of the nuclear power plant within the limits of the technical guidelines to increase the reliability of measurement and computer reading Possible recording media are disclosed. According to the present invention, in the control rod drop time analysis of the control rod control system in a nuclear power plant reactor, wavelet transforms the electromotive force signal induced when passing through the moving winding in the control rod drive device while the magnetic rod control shaft falls into the reactor. Approximation coefficients and detail coefficients are represented on the time axis by separating the wavelet function and the scale function of the signal, and the control point dropping start point and end point are automatically searched using the discontinuous line separation characteristic and the noise removal characteristic that the wavelet's scale changes. There is provided a method for measuring the drop time of a control rod that enables the control rod drop time to be accurately analyzed, and a computer-readable recording medium having recorded thereon a computer program for executing the method.

Control rod, wavelet, scale, approximation factor, detail factor, drop time

Description

METHOD AND COMPUTER-READABLE RECORDING MEDIUM FOR MEASURING ROD DROP TIME}

The present invention is to determine the drop time response of the control rod in accordance with the nuclear reactor emergency stop command during the planned preventive maintenance period of the nuclear power plant within the limits of the technical guidelines to increase the reliability of measurement and computer reading It relates to a possible recording medium.

In general, the control rods of a nuclear power plant control the core's responsiveness through insertion and withdrawal during normal operation to maintain the average coolant temperature corresponding to the reactor output. It is inserted into the core and serves to keep the reactor subcritical, making it one of the most important facilities for reactor safety.

In order to ensure safe reactor shutdown in the event of a reactor stop signal, each nuclear power plant measures the falling time of all control rods at a fixed cycle. This is to check if the technical guidelines are within the limits. It is specified to measure the time from the time when the stop rod signal is reduced by freely dropping the control rods from the fully drawn out position to the dashpot entry located under the control rod guide, to verify that the time is within the specified limits.

However, in the conventional method of measuring the drop time of the control rod, the trigger signal and the induced voltage signal (also referred to as an 'electromotive force signal') signal of the control rod selected from the data file stored in the analysis computer are expressed in the same time axis graph, and the analyst manually It is a method performed individually by selecting the control rod drop start point and the end point. This method of measuring the drop time of the control rod has a problem that the reliability is inferior because it generates different results of the analysis results according to the analyst's inclination, and a lot of time is required for the drop test analysis due to manual work.

The present invention is to solve the conventional problems as described above, by using a multi-resolution wavelet transform the electromotive force signal induced when passing through the moving winding in the control rod drive device while the control rod drive shaft is a magnetic body falls into the reactor By automatically searching for the start and end points, (i) improve the accuracy of the control rod fall time measurement, (ii) eliminate the human intervention of the control rod fall time analysis to increase the reliability of the measurement results, and (iii) control rod fall. It is an object of the present invention to provide a method for measuring the drop time of a control rod that shortens the time required for time analysis to increase utilization of a nuclear power plant, and a computer readable recording medium having recorded thereon a computer program for executing the method.

In order to achieve the object of the present invention as described above, and to perform the characteristic functions of the present invention described below, the characteristic configuration of the present invention is as follows.

According to an aspect of the present invention, when the control rod falls into the reactor, the control rod drop time is automatically and accurately measured using the multiresolution wavelet transform of Equation 1 as shown below. A method is provided.

Φ _{j, k} (x) is a scale function, Ψ _{j, k} (y) is a wavelet function, c _{j, k} is a scale coefficient or approximation coefficient, d _{j, k} is a wavelet coefficient or detail coefficient, j is a data position , k represents a resolution step.

Here, the approximation coefficient c _{j, k} is a low frequency region containing the overall characteristic information of the moving winding induced voltage from which signal noise is removed, and the detail coefficient d _{j, k} is the signal noise included in the induced voltage of the moving winding. And a high frequency region having detailed characteristic information.

Further, the drop start point of the control rod is defined as the time at which d ₄ becomes the maximum among the detailed coefficients by using the characteristic that the maximum value of the wavelet is separated when the signal discontinuity is encountered during the wavelet transformation. Can be represented.

In addition, at the time of entry of the braking arc of the control rod, the noise signal included in the electromotive force signal is obtained through the multi-resolution wavelet transform process to obtain c ₄ of the approximation coefficient from which the noise is removed, and the control rod reaches a minimum free fall. It may indicate that the time defined as the point from which the smallest after time c _4.

According to another aspect of the present invention, there is provided a computer readable recording medium having recorded thereon a computer program for executing the above method.

According to the present invention, by using the multi-resolution wavelet transform of the electromotive force signal, the computer program automatically searches the start and end points of the control rod drop in the time-scale region, thereby increasing the accuracy of the analysis, and artificial intervention of the analyst. In addition, the reliability of the analysis result is increased, and the drop signal is acquired for a plurality of control rods, thereby reducing the time required for the control rod drop time analysis, thereby increasing the utilization of the nuclear power plant.

The following detailed description of the invention refers to the accompanying drawings, which illustrate, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. It is to be understood that the various embodiments of the invention are different, but need not be mutually exclusive. For example, certain shapes, structures, and characteristics described herein may be embodied in other embodiments without departing from the spirit and scope of the invention with respect to one embodiment. In addition, it is to be understood that the location or arrangement of individual components within each disclosed embodiment may be changed without departing from the spirit and scope of the invention. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention, if properly described, is defined only by the appended claims, along with the full range of equivalents to which such claims are entitled. Like reference numerals in the drawings refer to the same or similar functions throughout the several aspects.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement the present invention.

Example of control rod drive

1 is a configuration diagram showing a control rod driving apparatus for performing a method for measuring a drop time of the control rod according to an embodiment of the present invention.

As shown in FIG. 1, a control rod driving apparatus according to an embodiment of the present invention is a jacking mechanism driven by magnetic force to insert, support, and lift the control rod 16 into the reactor core. ) Is provided with a lifting winding 11, a moving winding 10, and a stop winding 12 that are excited in a controlled order for insertion, support, and lifting. Here, the drive shaft bundle 17 attached to the control rod 16 may be made of stainless steel made of magnets to detect the position of the control rod 16 with a series of sense coils outside the reactor pressure housing. The driving device of the control rod described here is described in more detail in Korean Patent Registration No. 0273170, filed by Korea Electric Power Corporation and registered on September 01, 1997. Accordingly, it is to be understood that the content of registered 0273170 is employed as part of the present invention.

The process of measuring the control rod falling time for the purpose of the present invention through the control rod drive device described above will be described below. First, all the control rods 16 are drawn out as much as possible, and the stop latch 14 is operated by passing a current through the stop winding 12 located below the moving winding 10 to stop all the control rods 16.

The breaker is then operated to draw a fuse attached to the stop winding 12 or to cut off the power supply so that the current flowing in the stop winding is cut off to induce the control rod drop. Therefore, the catch of the stop latch 14 is released and the control rod 16 starts to fall. When the ferromagnetic control rod drive shaft falls through the lifting winding 11, the moving winding 10, and the stopping winding 12 in a falling motion, induced electromotive force is generated in the respective windings. For example, the induced electromotive force signal is generated in the moving winding 10 in the control rod drive during the drop rod control shaft. In this case, the induced electromotive force signal is a non-stationary signal having a multi-scale in which the physical characteristics of the signal change with time.

On the other hand, the signal acquisition device 15 collects the induced electromotive force of the moving winding 10 generated during the dropping motion of the control rod drive shaft to perform signal adjustment and sampling to analyze the falling time of the control rod, which will be described in more detail later.

Example of a voltage signal on a moving winding

2 is a graph illustrating a change in the voltage signal of the moving winding when the control rod falls according to an embodiment of the present invention.

As shown in Figure 2, immediately after the control rod drop start point (b) according to an embodiment of the present invention, the moving winding 10 voltage signal in the initial stage of the drop is cut off generated in the stop winding 12 to start the control rod fall The current is drastically reduced to the minimum voltage portion a. Subsequently, the induced voltage component appears predominantly in accordance with the change of the magnetic flux by the stop winding 12, and then remarkably decreases, and after the point (c) where the magnetic induction effect disappears and the induced voltage becomes the maximum, the pure control rod 16 falls. The induced voltage signal component of the moving winding 10 itself associated with starts to increase. At this time, the falling control rod 16 decelerates rapidly at the moment of entering the brake arc inlet in the control rod drive device. This phenomenon is an inflection point at which the sign of the slope is changed in the moving winding 10 signal, that is, the brake arc entry point d , The end of the control rod).

Therefore, the drop time of the control rod may be defined from the start point (b) of the drop to the start point (d) of the brake arc of the control rod, which is the first inflection point at which the sign of the slope changes. Here, the induced voltage signal generated near the control rod drop start point (b) is enlarged in FIG. 3, and the induced voltage signal generated near the inflection point (d) at which the control rod enters the brake arc inlet of the control rod and whose slope sign changes is shown. It is enlarged in 4 and shown.

The induced electromotive force signal of the moving winding 10 before the control rod drop start point (b) of the present invention shown in FIG. 3 includes the characteristics of the high frequency noise form, and shown in FIG. The induced voltage signal of the moving winding 10 is associated with a sinusoidal noise signal of a constant period, which is generated due to the relative positional relationship between the sawtooth and the sawtooth of the toothed control rod drive shaft.

Hereinafter, a method of automatically and accurately measuring the falling time of the actual control rod using the information obtained in FIGS. 2 to 4 will be described in more detail.

That is, when the control rod falls into the reactor, by using the multi-resolution wavelet transform of Equation 1 as shown in the electromotive force signal induced in the moving winding in the control rod drive device, it is possible to accurately measure the fall time of the control rod.

In other words, the method for measuring the drop time of the control rod of the present invention uses the discontinuous line separation characteristic of the wavelet to search for the control rod drop start point (b) among various wavelet transform characteristics, and includes a sinusoidal noise signal. The noise removal characteristic of the wavelet is used to search for the braking call entry time (d).

Φ _{j, k} (x) is a scale function, Ψ _{j, k} (y) is a wavelet function, c _{j, k} is a scale coefficient or approximation coefficient, d _{j, k} is a wavelet coefficient or detail coefficient, j is a data position , k denotes the resolution level.

Here, the approximation coefficient (c _{j, k} ) contains the overall characteristic information of the induced voltage of the moving winding 10 from which signal noise is removed as the low frequency region, and the detail coefficient (d _{j, k} ) is the high frequency region of the mobile winding. It contains the signal noise and detailed characteristic information included in the induced voltage of (10).

As shown in [Equation 1], in the method for measuring the drop time of the control rod according to the exemplary embodiment of the present invention, the induced voltage signal of the moving winding 10 may be separated into a wavelet function and a scale function using a multiresolution wavelet transform. It is possible to determine an approximation coefficient and a detailed coefficient. The induced voltage signal S of the original moving winding 10 including the multi-scale wavelet, for example, a Harr wavelet, has a resolution in one step according to [Equation 1]. Perform the approximation coefficient 'c ₁ ' and? It can be decomposed by the coefficient 'd ₁ '. This may be represented by a graph as shown in Figure 5, it can be represented by the following [Equation 2].

S = c ₁ + d ₁ [Formula 2]
Here, c ₁ represents an approximation coefficient in _one resolution step, and d ₁ represents a detail coefficient in one resolution step.

Then, the method fall time measurement the control rods in accordance with one embodiment of the present invention is approximated coefficient to perform the Harr wavelet at a resolution two-step in accordance with the approximation coefficient 'c _1' of the above [Equation 2] [Equation 1] 'c ₂ 'And the detail factor' d ₂ 'are decomposed again. This may be represented by a graph as shown in Figure 6, it can be represented by the following [Equation 3].

c ₁ = c ₂ + d ₂ [Formula 3]
Here, c ₂ represents an approximation coefficient in resolution 2 stages, and d ₂ represents a detail coefficient in resolution 2 stages.

Subsequently, the approximation coefficient 'c ₂ ' of the above [Equation 3] is Harr wavelet performed in three resolutions according to [Equation 1] to further decompose it into the approximation coefficient 'c ₃ ' and the detailed coefficient 'd ₃ '. This may be represented by a graph as shown in Figure 7, it may be represented by the following [Equation 4].

_{c 2 = c 3 + d 3} [ Expression 4]
Here, c ₃ represents an approximation coefficient at three resolution levels, and d ₃ represents a detailed coefficient at three resolution levels.

Subsequently, the approximation coefficient 'c ₃ ' of the above [Equation 4] is performed by Harr wavelet at four resolutions according to [Equation 1] to further decompose it into the approximation coefficient 'c ₄ ' and the detail coefficient 'd ₄ '. This may be represented by a graph as shown in Figure 8, it can be represented by the following [Equation 5].

c ₃ = c ₄ + d ₄ [Formula 5]
Here, c ₄ represents an approximation coefficient at four resolution stages, and d ₄ represents a detailed coefficient at four resolution stages.

Accordingly, the induced voltage signal S of the original moving winding 10 is obtained by performing the multiresolution analysis as shown in [Formula 2], [Formula 3], [Formula 4], and [Formula 5]. 6] is decomposed as shown.

S = c ₄ + d ₁ + d ₂ + d ₃ + d ₄ [Equation 6]

As in the above [Equation 6] and the process of Figures 5 to 8, the approximation coefficient (c) of the present invention has similar characteristics to the continuous low-frequency filter for the original signal (S), the expansion is in progress Accordingly, the scale of the induced voltage signal can be decreased by one step. On the other hand, it can be seen that the detail coefficient (d) has a stepwise band filter characteristic and a wavelet transform characteristic.

Based on the above results, falling start point (b) of the control rod identified in Figure 3, the wavelet conversion while, if it encounters a bulyeonsokseon of the induced voltage signal of the by the property that the maximum value of the wavelet separation, detailed coefficient d ₄ max It can be defined as the time of the point that becomes.

In addition, jedongho entry point of the control rod (d, falling end point of the control rod) is the noise signal included in the electromotive force signals are through the wavelet transform process of resolution of the approximate coefficients which noise is removed to obtain the c _4, the control rod is in free fall It can be defined as any minimum time to reach, for example, the point at which it becomes the minimum of c ₄ after the minimum time of 1 second.

As described above, in the method for measuring the drop time of the control rod according to the exemplary embodiment of the present invention, the drop start point and the end point of the control rod defined above are automatically searched in the time-scale region using the multi-resolution wavelet transform. This has the advantage of increasing the accuracy of the analysis.

On the other hand, as described above, the method for measuring the drop time of the control rod according to the embodiment of the present invention can be implemented in the form of program instructions that can be executed through various computer components can be recorded on a computer-readable recording medium. The computer-readable recording medium may be understood to include program instructions, data files, data structures, etc. alone or in combination.

Program instructions recorded on the computer-readable recording medium may be those specially designed and configured for the present invention, or may be known and available to those skilled in the computer software arts. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks and magnetic tape, optical recording media such as CD-ROMs, DVDs, and magneto-optical media such as floptical disks. media), and hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include not only machine code generated by a compiler, but also high-level language code that can be executed by a computer using an interpreter or the like. The hardware device may be configured to operate as one or more software modules to perform the process according to the invention, and vice versa.

1 is a configuration diagram showing a control rod driving apparatus for performing a method for measuring a drop time of the control rod according to an embodiment of the present invention.

2 is a graph illustrating a change in the voltage signal of the moving winding when the control rod falls according to an embodiment of the present invention.

3 is an enlarged graph illustrating an induced voltage signal generated near a control rod drop start point according to an exemplary embodiment of the present invention.

4 is an enlarged graph illustrating an induced voltage signal generated near a brake call entry point according to an exemplary embodiment of the present invention.

5 is a graph exemplarily illustrating a result of wavelet transform in a resolution 1 step of an induced voltage signal according to an exemplary embodiment of the present invention.

6 is a graph exemplarily illustrating a result of wavelet transform in two resolutions of an induced voltage signal according to an exemplary embodiment of the present invention.

7 is a graph exemplarily illustrating a result of wavelet transform in three resolution levels of an induced voltage signal according to an exemplary embodiment of the present invention.

8 is a graph exemplarily illustrating a result of wavelet transform in four resolutions of an induced voltage signal according to an exemplary embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

10: moving winding 11: raising winding

12: stop winding 14: stop latch

15: signal acquisition device 16: control rod

17: bunch of drive shaft

Claims (5)

When the control rod falls into the reactor, a method of automatically measuring the drop time of the control rod by using the multi-resolution wavelet transform of Equation 1 as follows: A first step of decomposition of c ₁ and d ₁ according to the formula 1, such as to the electromotive force signal (c ₁ denotes the approximate coefficients in the resolution step 1, d ₁ represents the detail coefficients in the resolution step 1); A second step decomposed to c ₂ and d ₂ in accordance with Equation 1, such as to the c ₁ (c ₂ represents the detail coefficients in represents an approximation coefficient, d ₂ is the resolution step 2 to step resolution 2); A third step of decomposing c ₃ and d ₃ in accordance with the formula (1), such as to the c ₂ (c ₃ represents the approximate coefficients in the resolution step 3, d ₃ represents the detail coefficients in the resolution step 3); A fourth step of decomposing to c ₄ and d ₄ according to formula 1, such as to the c ₃ (c ₄ represents the approximate coefficients in the resolution step 4, d ₄ represents the detail coefficients in the resolution step 4); A fifth step of defining a time at which d ₄ becomes a maximum as a drop start point of the control rod in order to take advantage of the fact that the maximum value of the wavelet is separated when a signal discontinuity is encountered during the wavelet transformation; And In order to use the characteristic that the noise is removed through the wavelet transform process, a sixth step of defining a time point at which the control rod becomes the minimum among c ₄ after a minimum time at which the control rod reaches free fall is defined as a falling end point of the control rod. Method for automatically measuring the fall time of the control rod comprising a.

Φ _{j, k} (x) is a scale function, Ψ _{j, k} (y) is a wavelet function, c _{j, k} is a scale coefficient or approximation coefficient, d _{j, k} is a wavelet coefficient or detail coefficient, j is a data position k denotes the resolution level. The method of claim 1, The approximation coefficient c _{j, k} is a low frequency region containing overall characteristic information of the induced voltage of the moving winding from which signal noise is removed, The detail coefficient d _{j, k} is a method for automatically measuring the fall time of the control rod, characterized in that the high frequency region having the signal noise and detailed characteristic information included in the induced voltage of the moving winding. When the control rod falls into the reactor, a method of automatically measuring the drop time of the control rod by using the multi-resolution wavelet transform of Equation 1 as follows: A first step of decomposition of c ₁ and d ₁ according to the formula 1, such as to the electromotive force signal (c ₁ denotes the approximate coefficients in the resolution step 1, d ₁ represents the detail coefficients in the resolution step 1); A second step decomposed to c ₂ and d ₂ in accordance with Equation 1, such as to the c ₁ (c ₂ represents the detail coefficients in represents an approximation coefficient, d ₂ is the resolution step 2 to step resolution 2); A third step of decomposing c ₃ and d ₃ in accordance with the formula (1), such as to the c ₂ (c ₃ represents the approximate coefficients in the resolution step 3, d ₃ represents the detail coefficients in the resolution step 3); A fourth step of decomposing to c ₄ and d ₄ according to formula 1, such as to the c ₃ (c ₄ represents the approximate coefficients in the resolution step 4, d ₄ represents the detail coefficients in the resolution step 4); And And a fifth step of defining a time at which d ₄ becomes a maximum as a drop start point of the control rod, in order to use a characteristic that the maximum value of the wavelet is separated when a signal discontinuity line is encountered during wavelet transformation. Method for automatically measuring the fall time of the control rod.

Φ _{j, k} (x) is a scale function, Ψ _{j, k} (y) is a wavelet function, c _{j, k} is a scale coefficient or approximation coefficient, d _{j, k} is a wavelet coefficient or detail coefficient, j is a data position k denotes the resolution level. When the control rod falls into the reactor, a method of automatically measuring the drop time of the control rod by using the multi-resolution wavelet transform of Equation 1 as follows: A first step of decomposition of c ₁ and d ₁ according to the formula 1, such as to the electromotive force signal (c ₁ denotes the approximate coefficients in the resolution step 1, d ₁ represents the detail coefficients in the resolution step 1); A second step decomposed to c ₂ and d ₂ in accordance with Equation 1, such as to the c ₁ (c ₂ represents the detail coefficients in represents an approximation coefficient, d ₂ is the resolution step 2 to step resolution 2); A third step of decomposing c ₃ and d ₃ in accordance with the formula (1), such as to the c ₂ (c ₃ represents the approximate coefficients in the resolution step 3, d ₃ represents the detail coefficients in the resolution step 3); A fourth step of decomposing to c ₄ and d ₄ according to formula 1, such as to the c ₃ (c ₄ represents the approximate coefficients in the resolution step 4, d ₄ represents the detail coefficients in the resolution step 4); And In order to use the characteristic that the noise is removed through the wavelet transform process, a fifth step of defining a time point at which the control rod becomes the minimum among c ₄ after a minimum time at which the control rod reaches free fall is defined as a falling end point of the control rod. Method for automatically measuring the fall time of the control rod comprising a.

Φ _{j, k} (x) is a scale function, Ψ _{j, k} (y) is a wavelet function, c _{j, k} is a scale coefficient or approximation coefficient, d _{j, k} is a wavelet coefficient or detail coefficient, j is a data position k denotes the resolution level. A computer-readable recording medium having recorded thereon a computer program for executing the method according to any one of claims 1 to 4.

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