JPH01212326A - Optical fiber linear temperature distribution measuring system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an optical fiber linear temperature distribution measuring system using an optical fiber linear temperature distribution measuring device using Raman scattered light.

[Prior art] An optical fiber linear temperature distribution measuring device using Raman scattered light is
Light with wavelength λ0, pulse width Tw, and pulse period Tp is input from one end of the optical fiber, and two components of Raman scattered light generated within the optical fiber are Stokes light with input wavelength S and anti-Stokes light with wavelength input aS. The backscattered light and the backscattered light of
(t).

f as(t), and their ratio f ax(t
) / fs (t) is purely a function of temperature,
And the time for the backscattered light returning from the distance line in the optical fiber to reach the optical fiber end (optical pulse input end) is 21/Ca from the pulse light input time, assuming that the speed of light in the optical fiber is Co. This is a device that takes advantage of this to measure linear temperature distribution along an optical fiber. Backscattered light measurement of Stokes light and anti-Stokes light is performed using O TDR (Opti
cal Ties Domain Reflectme
Try) Perform the measurement using almost the same method as the device.

A linear temperature distribution measurement system using an optical fiber linear temperature distribution measurement device using Raman scattered light can be used to measure the temperature distribution in the direction of the pitcher's force of the electric power cable by, for example, laying an optical fiber cable for a sensor along the electric power cable. This information can be used to control power transmission capacity, or to detect the location of high-temperature areas caused by deterioration of cables. It can also be used to control the temperature of production lines and equipment in various plants, and to detect fires in buildings, tunnels, etc. For example, it can be used to determine the location of a fire outbreak.

5 and 6 show an example of the configuration of a conventional optical fiber linear temperature distribution measurement system using Raman scattered light. This linear temperature distribution measurement system consists of a sensor optical fiber 5 and a temperature distribution measurement device 21. It consists of a temperature distribution measuring device 21
is composed of a temperature distribution measurement circuit 17 and a temperature distribution calculation processing/display circuit 16.

Optical pulse light source 11 for 0TDR of temperature distribution measuring device i21
The light emitted from the sensor is guided to the sensor optical fiber 5 through the optical fiber 18a and the optical splitter 4a. The backscattered light generated in the sensor optical fiber 5 is guided to the optical splitter 4b through the optical splitter 4a and the optical fiber 18d, where it is
Of the separated backscattered lights, the one guided to the optical fiber 18b is used to measure the anti-Stokes light by an anti-Stokes light measurement system consisting of an optical filter 10a with center wavelength input as, a light receiver 9a, and an averaging processing circuit 8a. By measurement,
It is used to find the function f as(t). Also, those guided to the optical fiber 18c.

The Stokes light measurement system consists of an optical filter 10b with center wavelength input S, an O/E transformation circuit for light reception, and an averaging processing circuit 8b.
5(t).

Then, the temperature distribution calculation processing circuit 7 calculates f as(t) /
By calculating fs(t), the linear temperature distribution along the sensor optical fiber 5 is measured.

[Problems to be solved by the invention] However, in the conventional optical fiber linear temperature distribution measurement system using Raman scattered light, the temperature measurement accuracy varies depending on the optical fiber loss up to the measurement position, and the measurement distance becomes long and the optical fiber loss increases. As temperature increases, temperature measurement accuracy decreases, so ±
With the current technology, the optical fiber length that can provide temperature measurement accuracy of 1° C. is limited to 2 km, making it difficult to accurately measure temperature distribution over long distances.

One way to measure temperature distribution over long distances is, for example, by installing a number of temperature distribution measuring devices and transmitting the measurement results using communication means other than the sensor optical fiber (for example, optical fiber communication or wireless communication). Data communication could be considered, but the equipment would be complicated and there would be problems in terms of economy and operability.

An object of the present invention is to provide an optical fiber linear temperature distribution measurement system using Raman scattered light, which eliminates the drawbacks of the prior art described above and can easily measure temperature distribution over a long distance without deteriorating accuracy. Our goal is to provide the following.

[Means for Solving the Problems] In order to achieve the above object, in the first aspect of the present invention, two optical fiber linear temperature distribution measuring devices using Raman scattered light are connected in cascade to an optical fiber for a sensor, Among the linear temperature distribution measuring devices, a sub-device located far from the main device connected to one end of the sensor optical fiber transmits temperature distribution measurement data measured by itself using the sensor optical fiber. The main device has a data reception function section that receives temperature distribution measurement data from the sub-device, and based on the received temperature distribution measurement data and the temperature distribution measurement data measured by its own device. An optical fiber linear temperature distribution measurement system is characterized in that it has a temperature distribution calculation processing unit that determines the temperature distribution of a long-distance optical fiber.

Further, in the second invention, three or more optical fiber linear temperature distribution measuring devices using Raman scattered light are connected in cascade to the optical fiber for the sensor, and one end of the optical fiber for the sensor is connected to the linear temperature distribution measuring device. The first sub-device located farthest from the main device has a transmission function section that transmits temperature distribution measurement data measured by itself to the main device using a sensor optical fiber. The second sub-device located between the first sub-device and the main device has a transmission function section that transmits temperature distribution measurement data measured by itself to the main device side using a sensor optical fiber, and The main device has a data receiving function that receives temperature distribution measurement data from the first sub-device and the second sub-device. and a temperature distribution calculation processing unit that calculates the temperature distribution of a long-distance optical fiber based on the received temperature distribution measurement data and the temperature distribution measurement data measured by the own device. A temperature distribution measurement system.

[Operation] In the first invention, the sub-device transmits temperature distribution measurement data measured by itself to the main device using a sensor optical fiber. The main device receives the temperature distribution measurement data from the sub-device, and determines the temperature distribution of the long-distance sensor optical fiber based on the received temperature distribution measurement data and the temperature distribution measurement data measured by the main device. Therefore, the main device and the sub device can accurately measure the linear temperature distribution in the section controlled by each device without requiring any other communication line (for example, optical fiber communication or wireless communication) other than the optical fiber for the sensor. As a result, long-distance linear temperature distribution can be measured with high accuracy.

In the first invention, there is only one sub-device, and it only has a transmission function to transmit temperature distribution measurement data to the main device, and does not require a data relay function, so when configuring a simple medium-distance device. suitable for

The second invention is a case where two or more sub-devices are installed,
The first sub-device located farthest from the main device transmits temperature distribution measurement data measured by itself to the main device using a sensor optical fiber. The second sub-device located between the first sub-device and the main device transmits the temperature distribution measurement data measured by itself to the main device using a sensor optical fiber, and also transmits the temperature distribution measurement data measured by itself to the main device side using a sensor optical fiber. The temperature distribution measurement data is relayed to the main device using a sensor optical fiber. The main device receives temperature distribution measurement data from the first and second sub-devices, and calculates the temperature distribution of the long-distance optical fiber based on these temperature distribution measurement data and the temperature distribution measurement data measured by its own device. demand. Therefore, in the second invention,
There is no limit to the length of the optical fiber for the sensor, and it is possible to measure linear temperature distribution over an extremely long distance and with high accuracy over the entire area.

[Example] Hereinafter, the present invention will be explained based on illustrated embodiments.

The optical fiber linear temperature distribution measurement system shown in Figure 1 is
It consists of a sensor optical fiber 5 and a plurality of optical fiber linear temperature distribution measuring devices using Raman scattered light that are cascaded to the sensor optical fiber 5. Among these linear temperature distribution measuring devices, the temperature distribution measuring device connected to one end of the sensor optical fiber 5 works as one M19, and the other temperature distribution measuring devices work as sub devices 120. The device 20 has temperature distribution measuring circuits 2 each connected to the sensor optical fiber 5 via an optical splitter 4, and each detects a line along the sensor optical fiber 5 by measuring the optical fiber backward Raman scattered light. Measure temperature distribution.

Although there is no limit to the number of sub-devices 20, for convenience of explanation below,
The case where there are two sub-devices will be described as an example, and they will be distinguished from each other as a first sub-device 201 and a second sub-device 202 as needed.

Each accessory! 20 includes a temperature information communication circuit 6 in addition to the temperature distribution measurement circuit 2. Among these, the first sub-device 201 located farthest from the first unit M19 transmits the temperature distribution measurement data measured by its own temperature distribution measurement circuit 2 to the main device 19 side using the sensor optical fiber 5. It has a temperature information communication circuit 62 including a functional section. In addition, the first sub-device 20
The second auxiliary equipment fi 202 is located between the main device 19 and the main device 19.

A transmitting function section transmits temperature distribution measurement data measured by the own temperature distribution measurement circuit 2 to the main device 19 side using the sensor optical fiber 5, and a transmission function section that transmits the temperature distribution measurement data from the first sub-device to the sensor optical fiber. The temperature information communication circuit 62 includes a relay function section that relays the information to the main device 19 using the temperature information communication circuit 62 using the temperature information communication circuit 62. On the other hand, the main device 19 includes a temperature distribution information receiving circuit 3 serving as a data receiving function unit that receives temperature distribution measurement data from the first sub-device 201 and the second sub-device 202, and a temperature distribution information receiving circuit 3 that serves as a data reception function unit that receives temperature distribution measurement data from the first sub-device 201 and the second sub-device 202, and a temperature distribution information receiving circuit 3 that receives temperature distribution measurement data from the first sub-device 201 and second sub-device 202. It has a calculation processing e calculation result output CPU circuit 1 for calculating the temperature distribution of a long-distance optical fiber based on the measured temperature distribution measurement data.

The temperature information communication circuits 61 and 62 and the temperature distribution information receiving circuit 3 are also connected to the sensor optical fiber 5 via the optical splitter 4.
It is connected to the.

Incidentally, if it is desired to lengthen the effective measurement distance, the number of the second sub-devices 202 is increased and these second sub-devices are installed between the first sub-device 201 and the main device 19.

The temperature distribution measurement data measured by the temperature distribution measurement circuit 2 of each sub-device 1201, 202 is first sent out as a digital optical signal from the first sub-device 201 farthest from the main device 19, and then sent to the second sub-device 201 on the way. relayed to the main device 1
After this relay is completed, the second sub-device 202 that reaches the second sub-device 202 transmits the temperature distribution measurement data measured by itself as a digital optical signal. If three or more sub-devices 20 are installed, repeat this operation in the following order.Finally, the main device 19's arithmetic processing/arithmetic result output CPU
The circuit 1 performs arithmetic processing on these digital temperature distribution measurement data and the temperature distribution measurement data measured by its own device, outputs the results, and displays them on a display device such as a CRT. Therefore, the distance between the main device 19 and the second sub-device 202 and the second
As long as the distance between the sub-device 202 and the first sub-device 201 is within the optical fiber length (2 km with current technology) that allows each temperature distribution measuring circuit 2 to measure temperature with a temperature measurement accuracy of ±1°C, it can be used over long distances. Temperature distribution can be measured without deterioration in accuracy.

If the sub-device 20 consists of only one first sub-device 201. which is the farthest from the main device 19, it is only necessary to send the temperature distribution measurement data measured by the self-device, so there is no special Although it is not necessary to provide a relay function section, in this embodiment, each of the sub-devices 201 and 202 has the same configuration as shown in FIG. It is set at 20.

That is, in FIG. 2, the temperature distribution measuring circuit 2 of the sub-device 2o includes optical splitters 4a and 4b for extracting the OTDRm optical pulse light 1111, the backward Raman scattered light, and an optical y4.
The filters 10a and 10b, the light receiving 0/E conversion circuits 9a and 9b that separate and detect 2TIt of Raman scattered light, the averaging processing circuits 8a and 8b that average each of them, and the temperature based on the results. It consists of a temperature distribution calculation processing circuit 7 that calculates the distribution. Further, the temperature information communication circuit 6 is connected to the optical branching device 4.
A temperature distribution information receiving circuit 14 receives an optical signal from another sub-device 2o further away from the main device 19 received by the light-receiving 0/E conversion circuit 9c, and extracts only digital data from this optical signal; A data switching circuit 12 that switches between relaying data from the device and transmitting data from the own device, and an E for data transmission.
10 conversion circuit 15 and OT from other devices on the main device 19 side
a light receiving 0/E conversion circuit 9d that receives the DR frequency optical pulse;
It is comprised of a timing generation circuit 13 that generates transmission timing from the optical pulses received by the light receiving 0/E conversion circuit 9d.

In the apparatus 120, the light emitted from the 0TDR optical pulse light source 11 of the temperature distribution measurement circuit 2 is guided to the sensor optical fiber 5 through the optical fibers 18a, 18e and the optical splitter 4. The light incident on the sensor optical fiber 5 has a wavelength o, a pulse width Tw, and a pulse period Tp.

The backscattered light generated in the sensor optical fiber 5 is transmitted to the optical splitter 4. The light is guided to the optical splitter 4b through the optical fiber 18e, the optical splitter 4a, and the optical fiber 18d, where it is divided into two optical fibers 18b and 18c. Of the backscattered light divided into two, the one guided to the optical fiber 18b is passed through an anti-Stokes optical measurement system consisting of an optical filter lOa with a center wavelength input as, a light receiving 07E conversion circuit 9a, and an averaging processing circuit 8a. 0TDR measurement of anti-Stokes light is performed and the function f as(t) is determined. That is, among the two components of Raman scattered light generated within the sensor optical fiber 5,
The back-scattered light of the anti-Stokes light of the wavelength input aS is a function of time f a with the pulse light incidence time being 1=0.
x(t). On the other hand, those guided to the optical fiber 18c include an optical filter 10b with a center wavelength input S;
A Stokes light measurement system consisting of a light receiving 07E conversion circuit 9b and an averaging processing circuit 8b performs 0TDR measurement of Stokes light, and a function f5(t) is determined. That is, of the two components of the Raman scattered light generated within the sensor optical fiber 5, the Stokes light of wavelength S is measured as a function fs(t) of one hour, with the pulsed light incidence time being 1=0.

The temperature distribution calculation processing circuit 7 includes averaging processing circuits 8a and 8b.
From the function obtained in , f ax(t) / f 5(t
) and calculate the ratio f ax(t) / f s
(t) is purely a function of temperature, and the time it takes for the backscattered light returning from the distance measurement in the optical fiber to reach the optical fiber end (light pulse input end) determines the speed of light in the optical fiber. Then, 21 /
Utilizing the fact that it is Co, the temperature distribution with respect to distance is calculated to obtain a linear temperature distribution along the optical fiber. Then, the temperature distribution data in the own device obtained as a result of the calculation processing is outputted to the temperature information communication circuit.

Next, the temperature information communication circuit 6 operates as follows. The timing generation circuit 13 generates a transmission timing from the optical pulse when the light receiving 0/E conversion circuit 9d receives the 0TDR optical pulse from the main device 19 or another sub-device 2G, and outputs the transmission timing to the data switching circuit. Trigger 12. As a result, the data switching circuit 12 is switched from the temperature distribution information receiving circuit 14 side to the temperature distribution calculation processing circuit 7 side.

Therefore, the adjustment alI 20 sends the temperature distribution data obtained by its own device to the main device 19 side in the form of a digital signal along with the 0TDR optical pulse from the main device 19 or another sub device 20. do.

, Now, the second vice? The temperature information communication circuit 62 in tII 202 and the temperature information communication circuit 61 in the first sub-device 201 have the same configuration, but the second sub-device 202 always receives the temperature distribution measurement data from the first sub-device 2ot. It has a function of relaying to the device 19 side, and this relay function is given priority over the transmission of temperature distribution measurement data obtained by the device itself.

That is, the optical signal from the first sub-device 201 is transmitted to the second sub-device 20.
2 and reaches the optical splitter 4. Via the optical fiber 18f,
It enters the 07E conversion circuit 9c for light reception. The light receiving 0/E conversion circuit 9c extracts only digital data from the received optical signal from the first sub-device 202. Since the data switching circuit 12 is normally switched to the temperature distribution information receiving circuit 14, the temperature distribution measurement data from the first sub-equipment F1201 immediately passes through the data switching circuit 12, and the data transmission E1
The signal is relayed to the main device 19 side via the 0 conversion circuit 15 and the optical branching device 4c.

The configuration of the main device 119 is shown in FIG. 3, and is common to the sub device 20 in that it has a temperature distribution measuring circuit 2, but also includes a temperature distribution information receiving circuit 14, a processor including a CPU, and a display device such as a CRT. Arithmetic processing/arithmetic result output CPU circuit 1
They are different in that they have the following. This arithmetic processing/arithmetic result output CPU circuit 1 receives the temperature distribution measurement data of the preparation 5?201, 202 received by the temperature distribution information receiving circuit 14 and the temperature distribution measurement data measured by the temperature distribution measurement circuit 2 of its own device. Based on this, the linear temperature distribution over the entire area of the sensor optical fiber 5 laid over a long distance is determined, and the results of the calculation processing are displayed.

In this way, one device A19 and one or more sub-devices 120 are connected in cascade to the sensor optical fiber 5, and the actual temperature distribution measurement is performed at a short distance that allows highly accurate measurement, and the measurement that integrates this information is performed. By doing so, highly accurate linear temperature measurement over long distances becomes possible. Therefore, for example, by laying an optical fiber cable for a sensor along a power cable, it is possible to know the temperature distribution in the longitudinal direction of the power cable and use it to control the power transmission capacity, etc. It is possible to perform position detection, etc. It can also be used to control the temperature of production lines and equipment in various plants, and to detect fires in buildings, tunnels, etc., for example, to locate the location of a fire outbreak.

In the above embodiment, the case where there are two sub-devices was explained.
Only one sub-device or three or more sub-devices may be provided, and when a simple system is configured with only one sub-device, there is no need for the sub-device to have a relay function.

Further, in the above embodiment, only linear temperature distribution information was transmitted, but by installing other sensors etc. in the sub-device 20 and transmitting sensor information using the communication means of the sub-device 20, equipment maintenance and It is also possible to apply it to systems such as monitoring. Additionally, a sub-device 2 is also provided at the farthest end of the sensor optical fiber 5.
0 is installed, a temperature sensor is installed in each sub-device 20, and the temperature sensor information is sent to the main device, so that the temperature distribution measurement circuit 2 of each preparation 2t20 can measure the temperature distribution based on the temperature sensor information. Data can be calibrated with one AT19, and a temperature distribution measurement system with improved temperature accuracy over long distances can be constructed.

Furthermore, as shown in FIG. 4, a temperature distribution measurement system with a branching function can be configured by combining a sub-device 22 that relays temperature distribution measurement data from two directions to the main device 19 side.

[Effects of the Invention] The present invention is a system in which temperature distribution measurement and data transmission can be performed simultaneously using the sensor optical fiber by connecting the main device and the sub-device in cascade with the sensor optical fiber. Therefore, there is no need for communication means other than the sensor optical fiber (for example, optical fiber communication, wireless communication, etc.).

main? i, a! By precisely measuring the linear temperature distribution in the section controlled by each unit and the sub-devices, and simply transmitting the measured temperature distribution measurement data, highly accurate linear temperature distribution measurement over a long distance can be achieved. Therefore, compared to the case of using communication means other than the sensor, the equipment is simplified, and accordingly, economical efficiency and operability can be improved.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of the temperature distribution measuring system of the present invention, FIG. 2 is a diagram showing an example of a functional configuration of a sub-device, and FIG. 3 is a diagram showing an example of a functional configuration of a main device. Fig. 4 shows an embodiment using a sub-device having a branching function, Fig. 5 shows an embodiment of a conventional temperature distribution measuring system, and Fig. 6 shows an example of the functional configuration of the measuring device. FIG. In the figure, l is an arithmetic processing/arithmetic result output CPU circuit, 2 is a temperature distribution measurement circuit, 3 is a temperature distribution information receiving circuit, 4 is an optical splitter, 5 is an optical fiber for sensor, 6 is a temperature information communication circuit, 7 is a temperature distribution calculation processing circuit, 8a and 8b are averaging processing circuits, 9a, 9b, 9c, and 9d are 07E conversion circuits for light reception, 10a and lOb are Gaku74 routers, and 11 is 0TDR.
14 is a temperature distribution information receiving circuit, 19 is a main device, and 20 is a sub device.

Claims (2)

[Claims] (1) Two optical fiber linear temperature distribution measuring devices using Raman scattered light are connected in cascade to the optical fiber for the sensor, and the main device connected to one end of the optical fiber for the sensor among the linear temperature distribution measuring devices The sub-device located far from the main device has a transmission function section that transmits temperature distribution measurement data measured by itself to the main device using a sensor optical fiber, and the main device transmits temperature distribution measurement data from the sub-device. It has a data reception function unit that receives data, and a temperature distribution calculation processing unit that calculates the temperature distribution of a long-distance sensor optical fiber based on the received temperature distribution measurement data and the temperature distribution measurement data measured by the own device. An optical fiber linear temperature distribution measurement system featuring: (2) Three or more optical fiber linear temperature distribution measuring devices using Raman scattered light are connected in cascade to the sensor optical fiber, and the main device connected to one end of the sensor optical fiber among the linear temperature distribution measuring devices On the other hand, the first sub-device located farthest from the main equipment has a transmission function section that transmits the temperature distribution measurement data measured by itself to the main equipment side using a sensor optical fiber. The second sub-device located between the main device and the second sub-device includes a transmission function section that transmits the temperature distribution measurement data measured by the second sub-device to the main device using a sensor optical fiber;
a relay function unit that relays temperature distribution measurement data from the first sub-device to the main device using a sensor optical fiber;
The main device has a data receiving function section that receives temperature distribution measurement data from the first and second sub-devices, and a long-distance sensor based on the received temperature distribution measurement data and the temperature distribution measurement data measured by its own device. 1. An optical fiber linear temperature distribution measurement system, comprising: a temperature distribution calculation processing section that determines the temperature distribution of an optical fiber.