JP2009243930A - Water level detection system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water level detection system which can automatically diagnose whether or not a detector is operating normally without inspecting it on the spot. <P>SOLUTION: The water level detection system comprises: a first detection means 60 which is connected to a first optical fiber which is laid so that it passes through a predetermined point within an area under monitoring; a second detection means 70 connected to a second optical fiber; a first measuring unit 30 which makes light incident on the first optical fiber and detects its reflected light; a second measuring unit 42 which makes light incident on the second optical fiber and detects its reflected light; and an arithmetic unit 10 for performing desired information processing from the measurement result of the first measuring unit and the measurement result of the second measuring unit. The arithmetic unit calculates the water level of an object under monitoring from the measurement result of the second measuring unit and determines whether or not the second measuring unit is normal from the measurement result of the first measuring unit and the measurement result of the second measuring unit, which are installed on the same point. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a remote monitoring system using an optical fiber and further to a water level detection system, and more particularly to a water level detection system having a self-diagnosis function of a water level gauge.

  In sewerage facilities, it is necessary to monitor the water level in preparation for overflow due to heavy rain. Conventionally, as an example of a device for detecting the water level, a device that mechanically and electrically detects the position of the float and a device that optically detects the water level itself and converts it into an electrical signal have been generally used. . However, these water level detectors have problems such as many mechanically movable parts that cause failure, and it is necessary to install a battery near the water level detector to secure the power supply of the electric circuit. It was.

Thus, in recent years, various inventions relating to an optical water level detector that measures the water level by utilizing the characteristics of an optical fiber called optical FBG (fiber Bragg grating) have been proposed (for example, Patent Document 1).
JP 2003-132774 A

  In Patent Document 1, a single-mode optical fiber for communication is sandwiched between a plate connected to a float using buoyancy via a shaft and a V-groove array having a diffractive surface composed of a plurality of V-grooves. A technique is disclosed in which a long-period grating is constructed and the water level is detected by monitoring the occurrence of loss at a specific wavelength due to the pressure applied to the fiber due to the buoyancy of the float generated according to the height of the water level.

  Furthermore, this Patent Document 1 uses a phenomenon that a specific wavelength at which a loss occurs is changed by changing the angle formed by the direction in which the V-groove of the V-groove array extends and the direction of the fiber. A technique is disclosed in which a plurality of long-period gratings having different V-groove angles are provided to detect water levels at a plurality of locations.

  However, in the water level detection system using the conventional optical FBG, it is impossible to know whether or not each detector is operating normally unless the water level is actually measured and measured by a measure or the like on site. Therefore, for example, in a sewer water level detection system, if the location where the detector is installed is a place where inspection work is difficult, such as a manhole under the roadway, or where toxic gas is present, the inspection cost There is a problem that becomes high.

  An object of the present invention is to provide a water level detection system capable of automatically diagnosing whether or not a detector is operating normally without actually performing an inspection on site.

  Another object of the present invention is to automatically diagnose the detector and reduce the total cost when there is a place where it is desired to detect whether or not the predetermined water level is reached in addition to the place where the accurate water level is desired to be detected. An object of the present invention is to provide a water level detection system capable of performing the above.

In order to achieve the above object, a water level detection system according to the present invention comprises:
A first transmission medium and a second transmission medium laid in parallel so as to pass through a predetermined location in the monitoring area, and a first detection means installed at the predetermined location and connected to the first transmission medium And a second detection means installed at the predetermined location and connected to the second transmission medium, and information to be monitored based on information from the first detection means supplied via the first transmission medium. A first measurement device for detecting a change, a second measurement device for detecting a change in a monitoring target based on information from the second detection means supplied via the second transmission medium, and the second A water level detection system comprising: a monitoring device that performs desired information processing from the measurement result of the first measurement device and the measurement result of the second measurement device;
The monitoring device calculates a water level to be monitored from the measurement result of the second measurement device, and the measurement result of the first measurement device and the measurement result of the second measurement device installed at the same location. To determine whether or not the second measuring device is normal.

  Here, it is preferable that the second transmission medium is an optical fiber, and the second measurement apparatus detects light reflected by entering light into the optical fiber. In addition, the first transmission medium is an optical fiber, and the first measurement apparatus detects light reflected by entering light into the optical fiber. Further preferably, the first measuring device detects whether or not the water level to be monitored exceeds a predetermined level set in advance.

  Preferably, the monitoring device has a predetermined result associated with the measurement result of the second measurement device when it is detected that the measurement value of the first measurement device exceeds a predetermined level. In comparison, it is determined whether or not the second measuring device is normal.

  Further, a plurality of first detection means each having a different detection level is installed corresponding to a location where the second detection means is installed, and each is connected to the first transmission medium.

  Further, the monitoring device determines whether or not the first detection means is normal based on a measurement result of the first measurement device based on information from the plurality of first detection means installed at the same location and having different detection levels. Is determined.

  Preferably, the first detection means is a reflection type detector in which the amount of reflected light changes when the water level to be monitored exceeds a predetermined level. In addition, the first measuring device is an OTDR that measures the reflected light on the time axis by entering pulsed light into the first transmission medium.

  Further preferably, the second detection means is a water level gauge having a fiber grating. In addition, the second measuring device includes a light source that makes a laser beam having a predetermined wavelength incident on the second transmission medium and a wavelength measuring device that measures the wavelength of reflected light from the second transmission medium. To do.

  Furthermore, in another aspect of the present invention, the first detection unit is installed corresponding to the location where the second detection unit is installed, while the second detection unit is installed at a location where the second detection unit is not installed. First detection means connected to the first transmission medium is provided.

  According to the present invention, it is possible to realize a water level detection system capable of diagnosing whether or not the detector is operating normally without actually inspecting at the site, thereby reducing maintenance costs. it can. A water level detection system that can automatically diagnose the detector and reduce the total cost when there is a place where it is desired to detect whether or not the predetermined water level has been reached in addition to the place where the accurate water level is to be detected. Can be realized.

Example 1
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings.

  FIG. 1 shows a first embodiment in the case where the present invention is applied to a water level detection system that wants to detect water levels at a plurality of places, for example, a sewer system, as an example.

  The water level detection system of this embodiment includes a centralized monitoring device 10 that centrally processes and analyzes signals from a plurality of water level sensors and outputs necessary information, and a first light under the control of the centralized monitoring device 10. An OTDR (Optical Time Domain Reflectometer) 30 that makes pulsed light incident on the fiber 21 and monitors reflected light, a light source 41 that makes laser light of a predetermined wavelength incident on the second optical fiber 22 via a circulator 51, and a second light source 41. A wavelength measuring device 42 for measuring the wavelength of the reflected light from the optical fiber 22 is provided. The circulator 51 functions as a directional coupler in which the laser light emitted from the light source 41 is incident on the second optical fiber 22 and the reflected light from the second optical fiber 22 is incident on the wavelength measuring device 42.

The 1st optical fiber 21 and the 2nd optical fiber 22 are laid in parallel so that it may pass through the place which wants to detect the water level in a monitoring area. Further, branching optical couplers 52a, 52b, 52c,... Are provided in the middle of the first optical fiber 21, and the branch fibers 21a, 21b, 21c,. Are connected, and the infiltration detectors 60a, 60b, 60c,... Are coupled to the ends of the branch fibers 21a, 21b, 21c,. The second optical fiber 22 is provided with optical water level meters 70a, 70b... Using FBG (fiber Bragg grating) in the middle. The optical water level meters 70a, 70b. It is a sensor (FBG sensor) having a rate modulation structure, and is installed in a manhole or the like where the water level is desired to be monitored in the sewer system. Since the FBG sensor is a reflection type sensor, there is an advantage that it is not necessary to provide a battery on the analog output sensor side, and maintenance is simplified.

  In this embodiment, the gratings are formed so that the FBG sensors (70a, 70b,...) Have different peak wavelengths (center wavelengths) of the reflected waves. The light source 20 is configured to output laser light in a wavelength region including peak wavelengths λa, λb,... Of all sensors connected to the optical fiber 10. In this way, by using FBG sensors having different center wavelengths, it is possible to identify from which location the reflected wave is located when installed at a plurality of locations.

  The OTDR 30 is a measuring device that detects a loss in the middle of the optical fiber and a distance to the point by measuring the reflected light from the first optical fiber 21 on the time axis. Such known OTDRs can be used in the present invention. The centralized monitoring device 10 is configured by an arithmetic device such as a computer capable of operating a program, and calculates the detected water level of each of the optical water level meters 70a, 70b... Based on the measured value by the wavelength measuring device 42, or measures the wavelength. It has a function of determining the presence or absence of abnormality of the optical water level meter from the measured values of the instrument 42 and the OTDR 30, and outputting the obtained information to the monitor 11 or the like. By using the OTDR, it is possible to identify where the reflected light is from the installed sensor, and it is possible to realize a monitoring system having a plurality of monitoring points at a low cost.

  In this embodiment, inundation detectors 60a, 60b,... Are installed corresponding to the optical water level meters 70a, 70b,... Provided in the middle of the second optical fiber 22. That is, the inundation detectors 60a, 60b,... Are always installed at the installation locations of the optical water level meters 70a, 70b,. On the other hand, even if an optical water level meter is not installed, an inundation detector may be installed (for example, 60c). The inundation detectors 60a, 60b, 60c... Are simpler and less expensive than the optical water level meters 70a, 70b... That detect whether or not the water level at the monitoring location has reached a predetermined level. It is a measuring instrument that can.

  As described above, a water level monitoring system that can collect information from many monitoring locations by installing an optical water level meter that provides an analog output and an inundation detector that provides a high or low binary output. It can be realized at low cost. Further, by using an optical fiber as an information transmission medium and using a light reflection type sensor as a detector, there is an advantage that it is not necessary to provide a battery on the detector side and maintenance is simplified.

  2 and 3 show an embodiment of a flood detector suitable for use in the water level detection system of FIG. FIG. 2 is a schematic view of the inundation detector, and FIG. 3 is a configuration diagram showing the internal structure. As shown in FIG. 2, the inundation detector 60 of this embodiment includes a magnetic detection proximity switch 62 housed and fixed in the upper half of the cylindrical protective cover 61, and a lower half of the protective cover 61. The end of branch fiber 21a, 21b, 21c ... is connected to the proximity switch 62, and the permanent magnet 64 is mounted on the upper surface of the float 63.

  The proximity switch 62 is a sensor that uses the magnetic Faraday effect. As shown in FIG. 3, the proximity switch 62 has a lens 65 facing the end face of the optical fiber, a birefringent element 66, a ring-shaped magnet 67, and this. The first Faraday rotator 68a, the second Faraday rotator 68b, and the reflection mirror 69 are arranged in series. When the float 63 rises as the water level rises and the permanent magnet 64 approaches the proximity switch 62, the internal Faraday rotators 68a and 68b rotate, the polarization plane rotates, and the light incident from the end face of the optical fiber is reflected by the reflection mirror 69. By reflecting strongly, it is notified by reflected light that the water level has risen above a predetermined level.

  FIG. 4 shows an example of a waveform measured by OTDR. The level of reflected light detected by the OTDR (loss in the optical fiber) is proportional to the distance, and in a normal time when the water level is low, a straight line descending to the right as shown in FIG. On the other hand, when the water level at the place where the inundation detector is installed rises, a beard-like waveform P due to the reflected light from the sensor is observed at a site corresponding to the distance to the installation place as shown in FIG. become.

  In FIG. 4B, La is a distance (fiber length) from the OTDR 30 to the water immersion detector 60a, Lb is a distance to the water immersion detector 60b, and Lc is a distance to the water immersion detector 60c. FIG. 4B shows a waveform when the inundation detector 60b detects a rise in the water level and the other inundation detectors 60a and 60c do not detect it. The centralized monitoring device 10 can know at which location the water level has reached the monitoring level by analyzing the waveform measured by the OTDR 30. The inundation detector is not limited to the one shown in FIGS. 2 and 3 and detects, for example, an increase in loss due to deformation of the optical fiber as disclosed in Japanese Patent Application Laid-Open No. 2003-166898. It may be of the type.

  Next, self-diagnosis processing of the optical water level meter by the centralized monitoring device 10 in the water level detection system of the present embodiment will be described with reference to the flowchart of FIG.

  The centralized monitoring device 10 determines whether or not the water level has reached the inundation detection level by using one of the inundation detectors 60a, 60b, 60c... From the measurement data of the OTDR 30. It transfers to S2 and it is determined whether the water level measured by the optical water level gauges 70a, 70b... Is higher than (the detection level of the inundation detector + α). Here, when “NO”, that is, when the measured water level of the optical water level meter is lower than (the detection level of the infiltration detector + α), it is determined that the water level meter is normal (step S4). If “YES”, that is, the measured water level of the optical water level meter is higher than (the detection level of the infiltration detector + α), it is determined that the water level meter is abnormal (step S5). α is an allowable error of the inundation detector and the optical water level meter.

  On the other hand, when it is determined in step S1 that any of the water detectors 60a, 60b, 60c... Has reached the water detection level, the process proceeds from step S1 to S3, and the corresponding optical water level gauges 70a, 70b. It is determined whether or not the measured water level is higher than (detection level of the inundation detector−α) and lower than (detection level of the inundation detector + α). Here, when “NO”, that is, when the measured water level of the optical water level meter is lower than (detection level of the inundation detector−α) or higher than (detection level of the inundation detector + α), the water level indicator is abnormal. Determine (step S5).

  If “YES” in step S3, that is, if it is determined that the measured water level of the optical water level meter is higher than (detection level of the inundation detector−α) and lower than (detection level of the inundation detector + α), the water level The total is determined to be normal (step S4). Each determination result is displayed on the monitor 11 or the like (step S6). Through the above processing, in the water level detection system of the present embodiment, the optical water level meter is automatically determined whether it is normal or abnormal without actually visiting the optical water level installation location and notifying the determination result. Be able to.

  As described above, since the water level detection system of the present embodiment has two water level monitoring systems, one system including the optical water level meters 70a, 70b,... Compared to a conventional water level detection system consisting only of a monitoring system, the cost is high. However, by having two monitoring systems, there is an advantage that it is possible to determine whether there is an abnormality in the optical water level meter.

  Further, depending on the monitoring target, it is not necessary to detect the accurate water level at all of the locations to be monitored, and there may be several locations where it is desired to detect whether or not the water level has simply reached a predetermined level. If this embodiment is applied to such a monitoring target, there is no need to install an expensive optical water level meter in every place where the water level is to be monitored. Can be suppressed.

(Example 2)
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings.

  FIG. 6 shows a second embodiment of a water level detection system to which the present invention is applied.

  The water level detection system according to this embodiment includes a branch fiber 21a, 21b, 21c,... And a water intrusion detector 60a through branch optical couplers 52a, 52b, 52c,. , 60b, 60c... Are provided in pairs, and each set of inundation detectors is configured to vary the detected water level. The other configuration is the same as that of FIG.

  According to the second embodiment, since two inundation detectors are provided for one water level meter, the normality / abnormality of each water level meter can be detected more accurately and the output of the paired inundation detectors can be detected. There is an advantage that the normality / abnormality of the inundation detector can be detected mutually.

  Next, self-diagnosis processing by the centralized monitoring device 10 in the water level detection system of the second embodiment will be described with reference to the flowchart of FIG.

  The centralized monitoring device 10 obtains the reflected light trend of each of the inundation detectors 60a, 60b, 60c,..., From the measurement data of the OTDR 30, that is, changes in detector sensitivity (steps S11 and S12). Then, it is determined whether the difference between the sensitivity of the inundation detector on the higher detection level and the sensitivity of the infiltration detector on the lower detection level is smaller than β and the sensitivity of each inundation detector is higher than γ. If it is determined that “NO”, that is, the difference in sensitivity is larger than β or any of the sensitivity of each inundation detector is smaller than γ, the process proceeds from step S13 to S14 and the inundation detector is abnormal. The determination is made and the determination result is output (step S25). Here, the sensitivity of the inundation detector corresponds to the relative height of the beard-like detection waveform in FIG. 4B (the height of the beard relative to the normal intensity of reflected light at the position). β and γ are constants appropriately set in advance according to the water immersion detector and OTDR to be used, respectively.

  Furthermore, in the second embodiment, it is determined from the measurement data of OTDR30 whether the water level has reached the inundation detection level with the inundation detector (upper) on the higher detection water level at any monitoring location, and the detection level. If not, the process proceeds from step S15 to S16, and it is determined whether or not the water level measured by the optical water level gauges 70a, 70b... Is higher than (the detection level of the inundation detector + α). Here, when “NO”, that is, when the measured water level of the optical water level meter is lower than (the detection level of the infiltration detector + α), it is determined that the water level meter is normal (step S18). If “YES”, that is, the measured water level of the optical water level meter is higher than (the detection level of the infiltration detector + α), it is determined that the water level meter is abnormal (step S19).

  Next, when it is determined in step S15 that one of the water detectors (upper) has reached the water detection level, the process proceeds from step S15 to S17, and measurement is performed by the corresponding optical water level gauges 70a, 70b. It is determined whether or not the water level is higher than (detection level of the submersion detector−α) and lower than (detection level of the submersion detector + α). Here, when “NO”, that is, when the measured water level of the optical water level meter is lower than (detection level of the inundation detector−α) or higher than (detection level of the inundation detector + α), the water level indicator is abnormal. Determination is made (step S19). In addition, when “YES”, that is, when the measured water level of the optical water level meter is higher than (detection level of the inundation detector−α) and lower than (detection level of the inundation detector + α), the water level meter is determined to be normal. (Step S18). When the abnormality is determined, the determination result is displayed on the monitor 11 or the like (step S25).

  Then, it transfers to step S20 and performs the process (S20-S25) similar to said step S15-S19 based on the measurement data of the submergence detector (lower) of the low detection water level of a monitoring place. Through the above processing, the water level detection system of the present embodiment automatically determines whether the optical water level meter and the inundation detector are normal or abnormal without going to the place where the optical water level meter is installed and actually measuring the water level. The judgment result can be notified.

  In addition, when the process of step S11-S14 in this embodiment is applied to the equipment which water level moves up and down comparatively frequently, or the equipment which can obtain measurement data by forcibly raising and lowering the water level of a monitoring place beforehand. It is an effective method. When applying to equipment where the water level does not fluctuate greatly for a long time and the water level rarely reaches the detection level, or equipment that does not have a function of forcibly raising or lowering the water level, the processing of steps S11 to S14 is omitted. Alternatively, the system may be configured to be executed when a predetermined amount of measurement data is accumulated by operating the system for a long period of time.

  Further, in the process of FIG. 7, it has been described that it is determined whether or not the inundation detector and the water level gauge are normal. However, in this embodiment, two inundation detectors are provided and the configuration is simple and fails. Because it is difficult to obtain information on on or off and the detection output is highly reliable, when calculating the measurement value of the water level based on the reflected wave from the water level gauge based on the information from the inundation detector It is also possible to perform processing that corrects the coefficients and constants of the formulas used, thereby increasing the water level measurement accuracy. This means that a highly accurate measurement result can be obtained over a long period of time even when the accuracy of the water level gauge changes over time, for example.

  Although the invention made by the present inventor has been specifically described based on the embodiment, the present invention is not limited to the above embodiment. For example, in the above-described embodiment, the case where an optical water level meter using FBG is used as a water level meter has been described. However, other water level meters (for example, optical path differences disclosed in Japanese Patent Application Laid-Open No. 2000-111361 are used). The present invention can also be applied when using a sensor that uses a water level gauge.

  In the second embodiment, the description has been given of the system in which two inundation detectors are provided. However, by providing three or more inundation detectors having different detection levels, that is, heights, the measurement accuracy and the reliability of the measurement value are improved. It is possible to further improve the configuration. Furthermore, in the second embodiment, a Faraday element is used as an inundation detector and an optical fiber is used as an information transmission medium. However, the information may be transmitted by an electrical signal using a cable or the like. good.

  In the above description, the case where the invention made mainly by the present inventor is applied to the water level detection system for sewerage facilities, which is the field of use behind it, has been explained. However, the water level detection system for rivers, dams, ponds, etc. It can also be used for systems that want to monitor changes in other physical quantities.

It is a block diagram which shows 1st Embodiment at the time of applying this invention to a water level detection system. It is a general-view figure which shows one Example of an inundation detector suitable for using for the water level detection system of FIG. It is a block diagram which shows the internal structure of the water immersion detector of FIG. An example of the measurement waveform by OTDR is shown, (A) is a waveform figure at normal time, (B) is a waveform figure at the time of a water level rise. It is a flowchart which shows an example of the procedure of the self-diagnosis process of the optical water level meter by the centralized monitoring apparatus in the water level detection system of 1st Embodiment. It is a block diagram which shows 2nd Embodiment of the water level detection system to which this invention is applied. It is a flowchart which shows an example of the procedure of the self-diagnosis process of the optical water level meter by the centralized monitoring apparatus in the water level detection system of 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Centralized monitoring apparatus 11 Monitor 21 1st optical fiber 22 2nd optical fiber 30 OTDR (Optical Time Domain Reflectometer)
41 Light source 42 Wavelength measuring device 51 Circulator 52 Optical coupler 60 Water immersion detector (second detection means)
61 Protective cover 62 Magnetic detection proximity switch 63 Float 64 Permanent magnet 65 Lens 66 Birefringent element 67 Ring magnet 68a First Faraday rotator 68b Second Faraday rotator 69 Reflecting mirror 70 Optical water level meter (second detection means)

Claims (12)

A first transmission medium and a second transmission medium laid in parallel so as to pass through a predetermined location in the monitoring area;
First detection means installed at the predetermined location and connected to the first transmission medium;
Second detection means installed at the predetermined location and connected to the second transmission medium;
A first measuring device for detecting a change in a monitoring target based on information from the first detection means supplied via the first transmission medium;
A second measuring device for detecting a change in a monitoring target based on information from the second detection means supplied via the second transmission medium;
A water level detection system comprising: a monitoring device that performs desired information processing from the measurement result of the first measurement device and the measurement result of the second measurement device,
The monitoring device calculates a water level to be monitored from the measurement result of the second measurement device, and the measurement result of the first measurement device and the measurement result of the second measurement device installed at the same location. To determine whether the second measuring device is normal or not.   2. The water level detection system according to claim 1, wherein the second transmission medium is an optical fiber, and the second measuring device detects light reflected by entering light into the optical fiber. 3. .   3. The water level detection system according to claim 2, wherein the first transmission medium is an optical fiber, and the first measurement device detects reflected light by entering light into the optical fiber. 4. .   The water level detection system according to any one of claims 1 to 3, wherein the first measuring device detects whether or not a water level to be monitored exceeds a predetermined level set in advance. .   The monitoring device compares the measurement result of the second measurement device when detecting that the measurement value of the first measurement device exceeds a predetermined level with predetermined data associated in advance with the first measurement device. The water level detection system according to claim 4, wherein it is determined whether or not the second measuring device is normal.   5. A plurality of first detection means each having a different detection level is installed corresponding to a location where the second detection means is installed, and each of the first detection means is connected to the first transmission medium. Or the water level detection system of 5.   The monitoring device determines whether or not the first detection unit is normal from the measurement result of the first measurement device based on information from the plurality of first detection units installed at the same location and having different detection levels. The water level detection system according to claim 6.   The water level detection system according to any one of claims 3 to 7, wherein the first detection means is a reflection type detector in which the amount of reflected light changes when the water level to be monitored exceeds a predetermined level. .   9. The water level detection system according to claim 8, wherein the first measuring device is an OTDR that measures the reflected light on a time axis by making pulsed light incident on the first transmission medium.   The water level detection system according to claim 2, wherein the second detection means is a water level meter having a fiber grating.   The second measuring apparatus includes a light source that makes a laser beam having a predetermined wavelength incident on the second transmission medium and a wavelength measuring device that measures the wavelength of reflected light from the second transmission medium. The water level detection system according to claim 10.   The first detection means is installed corresponding to the place where the second detection means is installed, and is installed in a place where the second detection means is not installed and connected to the first transmission medium. The water level detection system according to claim 1, further comprising a first detection unit.

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