JP2015064300A - Frequency detection device and method for calibrating frequency detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a frequency detection device eliminating the need for connection to a frequency generator for outputting a signal serving as a reference and capable of calculating and calibrating detection accuracy.SOLUTION: A frequency detection device 10 comprises: a measurement signal input unit 12 for inputting a process signal s measured at a plant; a diagnostic signal generation unit 13 for generating a diagnostic signal t serving as a reference during a diagnosis mode; a switching unit 14 for outputting the process signal s during a normal mode and outputting the diagnostic signal t during the diagnosis mode; a frequency calculation unit 16 for calculating a frequency from the process signal s outputted from the switching unit 14 by using a correction value during the normal mode, and calculating a frequency from the diagnostic signal t outputted from the switching unit 14 by using a correction value during the diagnosis mode; and an accuracy calculation unit 17 for calculating detection accuracy from an error between a frequency detected from the diagnostic signal t and a prescribed expected value.

Description

  Embodiments described herein relate generally to a calibration technique for a frequency detection device.

  In a thermal power plant or a nuclear power plant, a frequency such as a process signal measured from plant equipment, for example, a speed signal related to the rotational speed of a steam turbine, is detected using a frequency detection device. The detected frequency is constantly monitored by security personnel and provided for stable plant operation. For this reason, maintaining the detection accuracy of the frequency detection device is important in plant maintenance.

  In general, calculation of detection accuracy in a frequency detection apparatus is performed based on an error between a detection frequency and an expected value for a signal by connecting a frequency generator that outputs a reference signal to the apparatus. When the detection accuracy is out of the specified range, a calibration operation is performed using a frequency generator.

  Conventionally, various techniques for maintaining the detection accuracy of the frequency detection device have been studied. In Patent Document 1, the detection error is corrected by an approximate expression obtained from the frequency detection results in two different detection units. Techniques to do this are disclosed.

Japanese Patent No. 3340244

  As described above, the calculation and calibration work of the detection accuracy in the frequency detection apparatus needs to be connected to the frequency detector every time it takes work, and it takes a lot of time, which may reduce the operating rate of the apparatus.

  In addition, when the frequency detection device is installed in the vicinity of the turbine of the plant, it is necessary for the plant security staff to go to the installation site and connect the frequency generator every time calculation accuracy and calibration work are performed. , It was a work burden for security personnel.

  The present invention has been made in view of such circumstances, and provides a frequency detection device that enables calculation and calibration of detection accuracy without requiring connection to a frequency detector that outputs a reference signal. The purpose is to do.

  The frequency detection apparatus of this embodiment outputs a measurement signal input unit that inputs a process signal measured in a plant, a diagnostic signal generation unit that generates a reference diagnostic signal in the diagnostic mode, and the process signal in the normal mode On the other hand, a frequency is calculated using a correction value from the process signal output from the switching unit in the normal mode and the process signal output from the switching unit in the normal mode, and from the switching unit in the diagnostic mode. A frequency calculation unit that calculates a frequency using the correction value from the output diagnostic signal, and an accuracy calculation unit that calculates detection accuracy from an error between the frequency calculated from the diagnostic signal and a predetermined expected value, It is characterized by providing.

  ADVANTAGE OF THE INVENTION According to this invention, the frequency detection apparatus which enables calculation and calibration of a detection accuracy is provided, without connecting with the frequency generator which outputs the signal used as a reference | standard.

The block diagram of the frequency detection apparatus which concerns on 1st embodiment. A part of flowchart which shows the diagnostic operation of the detection accuracy in the frequency detection apparatus which concerns on 1st embodiment. A part of flowchart which shows the diagnostic operation of the detection accuracy in the frequency detection apparatus which concerns on 1st embodiment. The figure which illustrated the composition of the frequency detector concerning a second embodiment. The flowchart which shows the identification method of the fault location in the frequency detection apparatus which concerns on 2nd embodiment. The block diagram of the frequency detection apparatus which concerns on 3rd embodiment.

(First embodiment)
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
As shown in FIG. 1, a frequency detection device 10 (hereinafter referred to as a detection device 10) according to the first embodiment includes a measurement signal input unit 12 that inputs a process signal s measured in a plant, and a reference in a diagnosis mode. A diagnostic signal generator 13 for generating a diagnostic signal t, a process signal s in the normal mode, and a switching unit 14 for outputting the diagnostic signal t in the diagnostic mode, and a process output from the switching unit 14 in the normal mode. A frequency calculation unit 16 that calculates a frequency using the correction value from the signal s and calculates a frequency using the correction value from the diagnosis signal t output from the switching unit 14 in the diagnosis mode, and a frequency detected from the diagnosis signal t And an accuracy calculation unit 17 that calculates detection accuracy from an error between the predetermined expected value and the predetermined expected value.
Furthermore, when the detection accuracy calculated by the accuracy calculation unit 17 is not within the specified range, a correction value update unit 18 that updates the correction value based on the error is provided.

  The detection device 10 detects a frequency from the process signal s measured in the plant in the normal mode. On the other hand, in the diagnosis mode, the frequency is detected from the diagnosis signal t generated by the diagnosis signal generator 13. Then, the detection accuracy is calculated using the detected frequency, and when the detection accuracy is not within the specified range, the correction value is updated. Therefore, the detection apparatus 10 can perform calculation and calibration of detection accuracy by the apparatus alone.

  The mode change between the normal mode and the diagnostic mode is performed by a security officer selecting operation on the input display unit 23. The input display unit 23 may be provided in the detection device 10 as shown in FIG. 1 or may be provided in a location away from the detection device 10 and connected to the detection device 10 via a network such as a LAN. It is also good. By providing the input display unit 23 at a location away from the detection device 10, the security officer can remotely control the mode change between the normal mode and the diagnostic mode.

  The detection apparatus 10 includes a timer 22. The timer 22 instructs the diagnostic signal generator 13 and the switching unit 14 to change from the normal mode to the diagnostic mode at regular intervals. Thereby, since calculation and calibration of detection accuracy are automatically performed periodically, high detection accuracy can be maintained.

Each operation in the normal mode and the diagnostic mode will be specifically described.
First, the operation in the normal mode will be described.
The measurement signal input unit 12 is a process signal s measured at a plant, for example, a frequency signal detected by an electromagnetic pickup sensor 11 installed in the vicinity of the turbine, or a rotational speed of a turbine detected by a speed detector (not shown). The speed signal etc. concerning is input.

  The switching unit 14 switches a signal to be output to the frequency detection unit 24 according to each of the normal mode and the diagnostic mode. In the normal mode, the process signal s input from the measurement signal input unit 12 is output to the frequency detection unit 24 via the contact A.

  The frequency detection unit 24 detects the frequency of the signal output from the switching unit 14 and includes a waveform shaping circuit 15 and a frequency calculation unit 16 that perform waveform shaping of the signal. The frequency detection unit 24 includes various circuits or elements related to signal processing, such as an AD conversion circuit, in addition to the waveform shaping circuit 15 (not shown).

The frequency calculation unit 16 inputs the process signal s via the waveform shaping circuit 15 or the like, and calculates the frequency from the process signal s using the correction value held in the correction value holding unit 20. The correction value is a value set based on the amount of deviation between the frequency of the diagnostic signal t detected by the frequency detection unit 24 and the frequency (expected value) expected corresponding to the diagnostic signal t. By using this correction value, an accurate frequency is calculated from the process signal s.
The calculated frequency is output to the input display unit 23 and monitored by security personnel.

Subsequently, an operation in the diagnosis mode will be described.
The diagnostic signal generator 13 generates a reference diagnostic signal t and outputs the diagnostic signal t to the switching unit 14.

  The diagnostic signal generator 13 may be configured to be removable from the detection device 10 alone. In this case, the diagnostic signal generator 13 is periodically removed, and the frequency oscillation accuracy is calibrated alone. Thereby, calculation and calibration of detection accuracy with high reliability can be performed.

  The switching unit 14 switches the connection from the contact A to the contact B in the diagnosis mode. The diagnostic signal t input from the diagnostic signal generator 13 is output to the frequency detection unit 24 via the contact B.

  The diagnostic signal t output to the frequency detection unit 24 is input to the frequency calculation unit 16 via the waveform shaping circuit 15 and the like as in the normal mode. The frequency calculation unit 16 calculates a frequency from the diagnosis signal t using the correction value held by the correction value holding unit 20. The calculated frequency is output to the accuracy calculator 17.

  The accuracy calculation unit 17 calculates the detection accuracy from the error between the frequency calculated by the frequency calculation unit 16 and the expected value stored in advance in the expected value storage unit 19. Note that the expected value is the same value as the above-described expected value, and is a frequency expected in response to the diagnostic signal t.

  And the calculated detection accuracy is output to the input display part 23, and is confirmed by the security officer. In addition, when the error between the frequency calculated from the diagnostic signal t and the expected value is large and the detection accuracy is in an abnormal range, the accuracy calculation unit 17 outputs an accuracy error to the input display unit 23 to provide security personnel. Announcement of abnormality in detection accuracy.

  The correction value update unit 18 calculates the frequency calculated from the diagnostic signal t when the detection accuracy is not within the abnormal range and is not within the specified range (spec), in other words, when the detection accuracy can be calibrated by updating the correction value. And a correction value is calculated based on an error between the expected value and the expected value. Then, the correction value is updated by overwriting the obtained correction value on the correction value held in the correction value holding unit 20.

  After the correction value is updated, the accuracy calculation unit 17 calculates the detection accuracy from the error between the frequency calculated from the diagnostic signal t and the expected value again. When the calculated detection accuracy falls within the specified range, that is, when calibration is completed, the detection accuracy is output to the input display unit 23.

  On the other hand, if the detection accuracy does not fall within the specified range, the correction value is calculated again based on the error, and the correction value held in the correction value holding unit 20 is updated. The correction value is repeatedly updated until the detection accuracy falls within the specified range.

  The update number counter 21 counts the number of times the correction value is updated by the correction value update unit 18. When the number of updates reaches a predetermined number or more, the calibration of detection accuracy is impossible and an update number error is output to the input display unit 23 to notify the security personnel of the abnormality.

  2 and 3 are flowcharts showing the operation of the detection apparatus 10 according to the first embodiment in the diagnosis mode (see FIG. 1 as appropriate).

  First, the switching unit 14 switches the signal output to the frequency detection unit 24 to the diagnostic signal t generated by the diagnostic signal generating unit 13 (S10).

  Then, the frequency calculation unit 16 inputs the diagnostic signal t via the waveform shaping circuit 15 and the like, and calculates the frequency using the correction value held in the correction value holding unit 20 (S11).

  The accuracy calculator 17 calculates the detection accuracy from the error between the calculated frequency and the expected value (S12). When the calculated detection accuracy is not within the abnormal range and within the specified range, the detection accuracy is output to the input display unit 23 and confirmed by security personnel (S13: NO, S14: YES, S15).

  On the other hand, when the calculated detection accuracy is within the abnormal range, an accuracy error is output to the input display unit 23 and the process ends (S13: YES, S16).

  When the detection accuracy is not within the specified range, the correction value update unit 18 calculates and obtains a correction value based on the error (S14: NO, S17). Then, this correction value is overwritten with the correction value held in the correction value holding unit 20 to update the correction value (S18).

  The update count counter 21 counts the number of times the correction value is updated by the correction value update unit 18 (S19). Then, the update of the correction value is repeated until the detection accuracy falls within the specified range within a range where the number of updates is a predetermined number (S20: NO).

  If the number of updates is equal to or greater than the predetermined number, calibration of detection accuracy is impossible and an update number error is output to the input display unit 23, and the process ends (S20: YES, S21).

As described above, the detection apparatus 10 can calculate the detection accuracy by itself without requiring connection to a frequency generator that outputs a reference signal. If the detection accuracy is not within the specified range, the correction value is automatically updated and the detection accuracy can be calibrated.
For this reason, since the calculation of the detection accuracy and the calibration work in the detection device 10 can be completed in a short time, it is possible to suppress a decrease in the operation rate.

  In addition, by remotely operating the change between the normal mode and the diagnostic mode from the input display unit 23, it is not necessary for the security staff to go to the detection device 10 to perform the work, thereby reducing the work load.

(Second embodiment)
FIG. 4 shows a configuration example of the detection apparatus 10 according to the second embodiment. In addition, the same code | symbol is attached | subjected to the structure similar to 1st embodiment, and description is abbreviate | omitted about the overlapping operation | movement.

  The second embodiment is different from the first embodiment in that the diagnostic signal t output from the switching unit 14 is output to the frequency calculation unit 16 without passing through some circuits or elements of the frequency detection unit 24. A switch 25 is further provided for switching to the path n output to the frequency calculation unit 16 via this circuit or element. Note that switching of the switch 25 is performed by an operation of a security officer on the input display unit 23.

  The path n becomes a normal transmission path in the frequency detection unit 24. On the other hand, the path m is newly provided as a transmission path that does not include some circuits or elements of the frequency detection unit 24.

  Here, a case where the waveform shaping circuit 15 is a partial circuit of the frequency detection unit 24 will be described.

  When the aforementioned error (accuracy error or update count error) occurs in the diagnostic mode, the contact C of the switch 25 is switched to the contact D, and the transmission path of the diagnostic signal t is switched from the path n to the path m. In the case of an update number error, the number of times counted by the update number counter 21 is cleared before switching.

If the error does not occur after switching the transmission path from the path n to the path m, it can be specified that the cause of the error is due to the failure of the waveform shaping circuit 15.
On the other hand, if an error occurs in the same manner, it can be estimated that the cause of the error is that a circuit or element other than the waveform shaping circuit 15 has failed.

  FIG. 5 shows a flowchart showing a method for identifying a fault location in the detection apparatus 10 according to the second embodiment (see FIG. 4 as appropriate).

  When an error occurs in the diagnosis mode, the security officer switches the contact C of the switch 25 to the contact D, and switches the transmission path of the diagnosis signal t from the path n to the path m (S30).

  When the error does not occur after the transmission path is switched from the path n to the path m, the cause of the error is identified as a result of the failure of the waveform shaping circuit 15 (S31: NO, S33).

  On the other hand, if an error occurs in the same manner, it is estimated that the cause of the error is that a circuit or element other than the waveform shaping circuit 15 has failed (S31: YES, S32).

  In this way, the diagnostic signal t is transmitted by switching the path m that does not include a part of the circuit of the frequency detection unit 24 and the path n that includes this circuit, and whether or not an error has occurred is confirmed. This makes it possible to specify the location where the error has occurred.

(Third embodiment)
FIG. 6 shows a configuration diagram of the detection apparatus 10 according to the third embodiment. In addition, the same code | symbol is attached | subjected to the structure similar to 1st embodiment, and description is abbreviate | omitted about the overlapping operation | movement.

  The third embodiment is different from the first embodiment in that it further includes a simplified frequency detection unit 26 that inputs a process signal s and detects a frequency without using a correction value, and the accuracy calculation unit 17 includes a frequency calculation unit. 16, the detection accuracy is calculated from the error between the frequency calculated in 16 and the frequency detected from the simplified frequency detection unit 26, and the correction value update unit 18 determines that this error is detected when the calculated detection accuracy is not within the specified range. The correction value is updated based on the above.

  The simplified frequency detection unit 26 includes an AD conversion circuit and an F / V (Frequency to Voltage) conversion element (not shown), and simply detects a frequency from the process signal s without using a correction value. .

The accuracy calculator 17 calculates the detection accuracy from the error between the frequency detected by the simplified frequency detection unit 26 and the frequency calculated by the frequency calculator 16. The calculated detection accuracy is output to the input display unit 23.
Further, when the detection accuracy is not within the specified range, the correction value update unit 18 updates the correction value based on the error. Therefore, calibration of detection accuracy is performed in the normal mode.

  As described above, by using the simplified frequency detection unit 26, it is possible to calculate and calibrate the detection accuracy in the normal mode, so that high detection accuracy can be maintained.

  According to each frequency detection apparatus described above, by providing a diagnostic signal generator that generates a reference diagnostic signal in the diagnostic mode, it is not necessary to connect to a frequency generator that outputs a reference signal. Allows calculation and calibration of detection accuracy.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 10 Frequency detection apparatus 11 Electromagnetic pick-up sensor 12 Measurement signal input part 13 Diagnostic signal generation part 14 Switching part 15 Waveform shaping circuit 16 Frequency calculation part 17 Accuracy calculation part 18 Correction value update part 19 Expected value storage part 20 Correction value holding part 21 Update Number counter 22 Timer 23 Input display unit 24 Frequency detection unit 25 Switch 26 Simple frequency detection unit s Process signal t Diagnostic signal A, B, C, D Contact m, n Transmission path

Claims (9)

A measurement signal input unit for inputting a process signal measured in the plant;
A diagnostic signal generator for generating a reference diagnostic signal in the diagnostic mode;
A switching unit that outputs the process signal in the normal mode, and outputs the diagnostic signal in the diagnostic mode;
In the normal mode, the frequency is calculated using the correction value from the process signal output from the switching unit, and in the diagnostic mode, the frequency is calculated from the diagnostic signal output from the switching unit. A frequency calculation unit;
A frequency detection apparatus comprising: an accuracy calculation unit that calculates detection accuracy from an error between a frequency calculated from the diagnostic signal and a predetermined expected value.   The frequency detection device according to claim 1, further comprising a correction value update unit that updates the correction value based on the error when the detection accuracy calculated by the accuracy calculation unit is not within a specified range. .   The frequency detection device according to claim 1, further comprising a timer that instructs the diagnostic signal generation unit and the switching unit to change from the normal mode to the diagnostic mode at regular intervals.   4. The frequency detection device according to claim 1, wherein the accuracy calculation unit outputs an accuracy error when the calculated detection accuracy is in an abnormal range. 5.   The update number counter that counts the number of times the correction value is updated by the correction value update unit and outputs an update number error when the correction value is equal to or greater than a predetermined number of times, further comprising: 5. The frequency detection device according to claim 4.   The frequency detection apparatus according to claim 1, wherein the diagnostic signal generation unit is removable.   A path for outputting the diagnostic signal output from the switching unit to the frequency calculation unit without passing through some circuits or elements relating to frequency detection, and a path for outputting to the frequency calculation unit via this circuit or element; The frequency detection apparatus according to claim 1, further comprising a switch for switching between the frequency detection apparatus and the frequency detection apparatus. Further comprising a simplified frequency detection unit that inputs the process signal and detects the frequency without using the correction value;
The accuracy calculation unit calculates the detection accuracy from an error between the frequency calculated by the frequency calculation unit and the frequency detected from the simplified frequency detection unit,
The said correction update part updates the said correction value based on this error, when the said detection accuracy calculated is not in the said prescription | regulation range, The claim 1 characterized by the above-mentioned. The frequency detection apparatus described. Entering process signals measured at the plant;
Generating a reference diagnostic signal in the diagnostic mode;
Switching the output by the switching unit so as to output the process signal in the normal mode, while outputting the diagnostic signal in the diagnostic mode;
In the normal mode, the frequency is calculated using the correction value from the process signal output from the switching unit, and in the diagnostic mode, the frequency is calculated from the diagnostic signal output from the switching unit. Steps,
Calculating detection accuracy from an error between a frequency calculated from the diagnostic signal and a predetermined expected value;
If the calculated detection accuracy is not within a specified range, updating the correction value based on the error;
A method for calibrating a frequency detection device comprising:

Images