CN103033285A - Simultaneous measurement method of temperature and strain of laid photoelectric composite cable - Google Patents

Abstract

Translated fromChinese

本发明公开了属于测量技术领域，特别涉及一种已敷设光电复合缆的温度和应变同时测量方法。该方法测量光电复合缆中传感光纤样纤的布里渊散射频移初值、谱峰功率初值和瑞利散射功率值，计算布里渊散射谱峰功率与瑞利散射功率之比；通过标定实验获得传感光纤样纤布里渊散射频移的温度和应变系数、布里渊散射相对谱峰功率的温度和应变系数；计算已敷设光电复合缆中传感光纤的布里渊谱峰功率分布初值的估计值；通过布里渊散射测量系统实时测量已敷设光电复合缆中传感光纤的布里渊散射频移分布和谱峰功率分布，计算传感光纤上的实时温度和应变分布；本发明在没有明显增加系统复杂性的前提下，解决了温度和应变同时测量的难题。

The invention discloses a measuring method belonging to the technical field, in particular to a method for simultaneously measuring temperature and strain of a laid photoelectric composite cable. The method measures the initial value of the Brillouin scattering frequency shift, the initial value of the spectral peak power and the value of the Rayleigh scattering power of the sensing optical fiber in the photoelectric composite cable, and calculates the ratio of the peak power of the Brillouin scattering spectrum to the Rayleigh scattering power; Obtain the temperature and strain coefficient of the sensing fiber-like fiber Brillouin scattering shift, the temperature and strain coefficient of the Brillouin scattering relative spectral peak power through the calibration experiment; calculate the Brillouin spectrum of the sensing fiber in the laid photoelectric composite cable The estimated value of the initial value of the peak power distribution; real-time measurement of the Brillouin scattering frequency shift distribution and spectral peak power distribution of the sensing fiber in the laid photoelectric composite cable through the Brillouin scattering measurement system, and the real-time temperature and spectral peak power distribution on the sensing fiber are calculated. Strain distribution; the present invention solves the problem of simultaneously measuring temperature and strain without significantly increasing the complexity of the system.

Description

Translated fromChinese

一种已敷设光电复合缆的温度和应变同时测量方法A Simultaneous Measurement Method of Temperature and Strain of Laid Photoelectric Composite Cable

技术领域technical field

本发明属于测量技术领域，特别涉及一种已敷设光电复合缆的温度和应变同时测量方法。The invention belongs to the technical field of measurement, in particular to a method for simultaneously measuring temperature and strain of a laid photoelectric composite cable.

背景技术Background technique

布里渊光时域反射技术是一种新型测量技术，它基于光纤中的自发布里渊散射信号实现温度或应变的测量，具有只需一次测量即可同时获取沿整个光纤被测场分布信息，响应速度快、测量精度高、定位准确、抗电磁干扰能力强、绝缘性能好、传感距离长等独特优点。布里渊光时域反射技术可实现对光纤沿线温度/应变分布的实时测量，特别适合于复合有普通通信用单模光纤的光电复合缆的状态监测，可及时发现故障隐患并进行高精度、快速准确定位，从而有效地保证电缆的正常工作。Brillouin optical time domain reflectometry is a new type of measurement technology, which is based on the spontaneous Brillouin scattering signal in the optical fiber to measure temperature or strain, and can simultaneously obtain the distribution information of the measured field along the entire optical fiber with only one measurement. , Fast response, high measurement accuracy, accurate positioning, strong anti-electromagnetic interference ability, good insulation performance, long sensing distance and other unique advantages. Brillouin optical time-domain reflectometry technology can realize real-time measurement of temperature/strain distribution along the optical fiber, especially suitable for condition monitoring of optical-electrical composite cables compounded with single-mode optical fibers for ordinary communication, and can detect hidden faults in time and carry out high-precision, Fast and accurate positioning, thus effectively ensuring the normal work of the cable.

目前的布里渊光时域反射技术基于光纤中自发布里渊散射的频移信息获得光纤沿线的温度或应变信息。布里渊散射频移变化正比于光纤的温度或应变变化，但当光纤同时受到温度或应变时，布里渊光时域反射技术只通过布里渊散射频移无法区分温度和应变，即存在交叉敏感问题。针对该问题，广大科研人员进行了大量的研究。The current Brillouin optical time-domain reflectometry technology obtains temperature or strain information along the fiber based on the frequency shift information of self-Brillouin scattering in the fiber. The change of Brillouin scattering frequency shift is proportional to the temperature or strain change of the fiber, but when the fiber is subjected to temperature or strain at the same time, the Brillouin optical time domain reflectometry technology cannot distinguish between temperature and strain only through the Brillouin scattering frequency shift, that is, there is Cross-sensitivity issues. Aiming at this problem, many researchers have conducted a lot of research.

一种同时测量温度和应变的方法是使用两种具有不同布里渊散射频移-温度/应变系数的光纤对同一条复合缆进行测量。根据布里渊散射频移温度和应变系数的不同求解二元一次方程组，同时得到温度和应变。此法无需测量布里渊散射谱峰功率，只通过布里渊散射频移一个参量的测量即可。但此方法需要两种特性差异较大的光纤作为传感介质，而一般光电复合缆中的光纤性质是很接近的，因此，不适合已经敷设好的光电复合缆使用。One way to measure temperature and strain simultaneously is to use two optical fibers with different Brillouin dispersion shift-temperature/gauge coefficients on the same composite cable. According to the difference of Brillouin scattering frequency shift temperature and strain coefficient, the binary linear equations are solved, and the temperature and strain are obtained at the same time. This method does not need to measure the peak power of the Brillouin scattering spectrum, but only needs to measure a parameter of the Brillouin scattering frequency shift. However, this method requires two kinds of optical fibers with greatly different characteristics as the sensing medium, and the properties of the optical fibers in the general photoelectric composite cable are very close, so it is not suitable for the already laid photoelectric composite cable.

另一种分离温度和应变的方法是同时使用布里渊温度/应变传感设备和拉曼温度传感设备。由于拉曼散射功率只对温度敏感，因此可用拉曼设备进行温度测量，而后补偿布里渊设备的温度应变交叉敏感特性，单独解出应变。此法需要两台设备同时工作，增加了系统的复杂性和成本，降低了测量的实时性。而且拉曼设备一般需用多模光纤，而光电复合缆中一般都是普通通信用单模光纤，个别拉曼设备也能使用单模光纤，但价格昂贵、测量距离较短，难以和布里渊设备相比。Another way to separate temperature and strain is to use both Brillouin temperature/strain sensing devices and Raman temperature sensing devices. Since Raman scattering power is only sensitive to temperature, Raman equipment can be used for temperature measurement, and then the temperature-strain cross-sensitivity characteristic of Brillouin equipment can be compensated to solve the strain independently. This method requires two devices to work at the same time, which increases the complexity and cost of the system and reduces the real-time performance of the measurement. Moreover, Raman equipment generally needs to use multi-mode optical fiber, while optical-electrical composite cables generally use single-mode optical fiber for ordinary communication, and individual Raman equipment can also use single-mode optical fiber, but it is expensive and the measurement distance is short, so it is difficult to compare with Brillouin. equipment compared.

综上所述，发明一种只使用一套布里渊散射测量系统就能够同时测量温度和应变，且适用于测量已敷设光电复合缆的方法十分必要。In summary, it is necessary to invent a method that can measure temperature and strain simultaneously using only one set of Brillouin scattering measurement system, and is suitable for measuring the laid photoelectric composite cable.

发明内容Contents of the invention

本发明的目的在于，提出一种已敷设光电复合缆的温度和应变同时测量方法，用于解决利用单设备、单光纤测量光电复合缆温度和应变时，已敷设光电复合缆布里渊散射谱峰功率初值无法获取，无法同时区分温度和应变的问题。The object of the present invention is to propose a method for simultaneously measuring the temperature and strain of the laid photoelectric composite cable, which is used to solve the problem of the Brillouin scattering spectrum of the laid photoelectric composite cable when using a single device and a single optical fiber to measure the temperature and strain of the photoelectric composite cable. The initial value of the peak power cannot be obtained, and the temperature and strain cannot be distinguished at the same time.

为了实现上述目的，本发明提出的技术方案是，一种已敷设光电复合缆的温度和应变同时测量方法，其特征是所述方法包括：In order to achieve the above object, the technical solution proposed by the present invention is a method for simultaneously measuring the temperature and strain of a laid photoelectric composite cable, characterized in that the method includes:

步骤1：测量光电复合缆中传感光纤样纤的布里渊散射频移初值、谱峰功率初值和瑞利散射功率值，计算布里渊散射谱峰功率与瑞利散射功率之比；Step 1: Measure the initial value of the Brillouin scattering frequency shift, the initial value of the spectral peak power and the Rayleigh scattering power value of the sensing fiber sample fiber in the photoelectric composite cable, and calculate the ratio of the peak power of the Brillouin scattering spectrum to the Rayleigh scattering power ;

取一段待测光电复合缆中复合光纤的样品（简称样纤），将样纤松弛地放在恒温装置内，保证其处于零应变、T₀℃下，用瑞利散射测量系统测量样纤的瑞利散射功率，获得一维数组，求平均后得到瑞利散射功率初值P_R0；用布里渊散射测量系统测量样纤的布里渊散射频移和谱峰功率，得到两个一维数组，分别求平均后得到布里渊散射频移初值v_B0和谱峰功率初值P_B0；根据C_BR =P_B0/P_R0计算零应变、T₀℃下的布里渊散射谱峰功率与瑞利散射功率的系数比C_BR；Take a sample of the composite optical fiber in the photoelectric composite cable to be tested (referred to as the sample fiber), and place the sample fiber loosely in the constant temperature device to ensure that it is at zero strain and T₀ ℃, and use the Rayleigh scattering measurement system to measure the sample fiber. Rayleigh scattering power, obtain a one-dimensional array, and obtain the initial value P_R0 of Rayleigh scattering power after averaging; use the Brillouin scattering measurement system to measure the Brillouin scattering frequency shift and spectral peak power of the sample fiber, and obtain two one-dimensional The initial value of the Brillouin scattering frequency shift v_B0 and the initial value of the spectral peak power P_B0 are obtained after averaging; the Brillouin scattering spectrum peak at zero strain and T₀ ℃ is calculated according to C_BR =P_B0 /P_R0 The coefficient ratio C_BR of power to Rayleigh scattered power;

步骤2：通过标定实验获得传感光纤样纤布里渊散射频移的温度和应变系数、布里渊散射相对谱峰功率的温度和应变系数；Step 2: Obtain the temperature and gauge coefficient of the sensing fiber-like fiber Brillouin scattering frequency shift, and the temperature and gauge coefficient of the Brillouin scattering relative spectral peak power through calibration experiments;

利用恒温装置和应变施加装置对样纤进行标定实验，施加的温度和应变点在5个以上，记录不同温度和应变下的布里渊散射频移v_B和谱峰功率P_B，利用线性拟合算法获取频移v_B和相对谱峰功率P_B/ P_B0分别与温度T和应变ε的线性关系，得到频移的温度系数C_vT、频移的应变系数C_vε、相对谱峰功率的温度系数C_PT、相对谱峰功率的应变系数C_Pε；Calibrate the sample fiber with a constant temperature device and a strain application device. The applied temperature and strain points are more than 5, and the Brillouin scattering frequency shift v_B and spectral peak power P_B under different temperatures and strains are recorded. Combining algorithm to obtain the linear relationship between frequency shift v_B and relative spectral peak power P_B / P_B0 and temperature T and strain ε respectively, and obtain temperature coefficient C_vT of frequency shift, strain coefficient C_vε of frequency shift, and relative spectral peak power Temperature coefficient C_PT , gauge coefficient C_Pε of relative spectral peak power;

步骤3：计算已敷设光电复合缆中传感光纤的布里渊谱峰功率分布初值的估计值；Step 3: Calculate the estimated value of the initial value of the Brillouin spectrum peak power distribution of the sensing fiber in the laid photoelectric composite cable;

使用同一套瑞利散射测量系统对已敷设光电复合缆中用于传感的光纤（简称传感光纤）进行一次测量，获得瑞利散射功率数据P_R(z)。计算传感光纤在零应变、T₀℃下的布里渊散射谱峰功率分布估计值P_B0(z)=C_BR×P_R(z)，其中z是某时刻散射光在传感光纤上的位置，其最大值是传感光纤长度；Use the same set of Rayleigh scattering measurement system to measure the optical fiber used for sensing in the laid photoelectric composite cable (sensing optical fiber for short), and obtain the Rayleigh scattering power data P_R (z). Calculate the estimated value of the peak power distribution of the Brillouin scattering spectrum of the sensing fiber at zero strain and T₀ ℃ P_B0 (z)=C_BR ×P_R (z), where z is the scattered light on the sensing fiber at a certain moment The position of , the maximum value of which is the length of the sensing fiber;

步骤4：通过布里渊散射测量系统实时测量已敷设光电复合缆中传感光纤的布里渊散射频移分布和谱峰功率分布，计算传感光纤上的实时温度和应变分布；Step 4: Measure the Brillouin scattering frequency shift distribution and spectral peak power distribution of the sensing fiber in the laid photoelectric composite cable in real time through the Brillouin scattering measurement system, and calculate the real-time temperature and strain distribution on the sensing fiber;

使用布里渊散射测量系统对传感光纤进行在线测量，可得到传感光纤上的布里渊散射频移分布v_B(z)和布里渊散射谱峰功率分布P_B(z)，然后计算传感光纤上的温度和应变分布：Using the Brillouin scattering measurement system to measure the sensing fiber online, the Brillouin scattering frequency shift distribution v_B (z) and the Brillouin scattering peak power distribution P_B (z) on the sensing fiber can be obtained, and then calculated Sensing the temperature and strain distribution on the optical fiber:

1）计算布里渊散射频移变化量δv_B(z)=v_B(z)-v_B0；1) Calculate the variation of Brillouin scattering frequency shift δv_B (z)=v_B (z)-v_B0 ;

2）计算布里渊谱峰功率相对变化量δP_B(z)/ P_B0(z)=(P_B(z)-P_B0(z))/ P_B0(z)；2) Calculate the relative change in Brillouin spectrum peak power δP_B (z)/ P_B0 (z)=(P_B (z)-P_B0 (z))/ P_B0 (z);

3）计算传感光纤上的温度分布T(z)和应变分布ε(z)：3) Calculate the temperature distribution T(z) and strain distribution ε(z) on the sensing fiber:

$\left[\begin{array}{c}T\left(z\right)\\ \mathrm{\ϵ}\left(z\right)\end{array}\right]=\frac{1}{|C_{\mathrm{\νT}}{C}_{\mathrm{P\ϵ}}-C_{\mathrm{\ν\ϵ}}{C}_{\mathrm{PT}}|}\left[\begin{array}{cc}{C}_P& -C_{\mathrm{\ν\ϵ}}\\ -C_{\mathrm{PT}}& C_{\mathrm{\νT}}\end{array}\right]\left[\begin{array}{c}{\mathrm{\δ\ν}}_B\left(z\right)\\ \frac{\mathrm{\δ}{P}_B\left(z\right)}{P_{B0}\left(z\right)}\end{array}\right]+\left[\begin{array}{c}{T}_0\\ 0\end{array}\right]$, 其中， |C_νTC_Pε-C_νεC_PT|≠0。$\left[\begin{array}{c}T\left(z\right)\\ \mathrm{\ϵ}\left(z\right)\end{array}\right]=\frac{1}{|C_{\mathrm{\νT}}{C}_{\mathrm{P\ϵ}}-C_{\mathrm{\ν\ϵ}}{C}_{\mathrm{PT}}|}\left[\begin{array}{cc}{C}_P& -C_{\mathrm{\ν\ϵ}}\\ -C_{\mathrm{PT}}& C_{\mathrm{\νT}}\end{array}\right]\left[\begin{array}{c}{\mathrm{\δ\ν}}_B\left(z\right)\\ \frac{\mathrm{\δ}{P}_B\left(z\right)}{P_{B0}\left(z\right)}\end{array}\right]+\left[\begin{array}{c}{T}_0\\ 0\end{array}\right]$ , where |C_νT C_Pε -C_νε C_PT |≠0.

所述待测光电复合缆中复合光纤的样品的长度应大于2米。The sample length of the composite optical fiber in the photoelectric composite cable to be tested should be greater than 2 meters.

本发明的有益效果：1、本发明克服了现有布里渊光时域反射计不能对已敷设光电复合缆进行温度和应变分布区分测量的缺点，通过合理利用布里渊散射谱峰功率，同时解出了温度和应变分布。2、通过分析样纤中布里渊散射测量系统和瑞利散射测量系统测量数据的关系，获得了已敷设光电复合缆中参考温度和应变下的布里渊谱峰功率分布，进而解决了布里渊谱峰功率与温度和应变的关系式中功率变化难以获得的问题。3、该发明只需一次瑞利散射测量系统测量即可获得参考功率，在以后长期的温度和应变同时监测中，只需布里渊散射测量系统一台设备即可。4、在没有明显增加系统复杂性的前提下，解决了温度和应变同时测量的难题。Beneficial effects of the present invention: 1. The present invention overcomes the shortcoming that the existing Brillouin optical time domain reflectometer cannot measure the temperature and strain distribution of the laid photoelectric composite cable, and by rationally utilizing the peak power of the Brillouin scattering spectrum, The temperature and strain distributions are solved simultaneously. 2. By analyzing the relationship between the measurement data of the Brillouin scattering measurement system and the Rayleigh scattering measurement system in the sample fiber, the Brillouin spectrum peak power distribution under the reference temperature and strain of the laid photoelectric composite cable is obtained, and then the solution It is difficult to obtain the power change in the relationship between the peak power of the Liouin spectrum and the temperature and strain. 3. The invention only needs one measurement of the Rayleigh scattering measurement system to obtain the reference power. In the long-term simultaneous monitoring of temperature and strain in the future, only one device of the Brillouin scattering measurement system is required. 4. On the premise of not significantly increasing the complexity of the system, the problem of simultaneous measurement of temperature and strain is solved.

附图说明Description of drawings

图1为样纤温度标定装置的连接示意图；Fig. 1 is the connection diagram of sample fiber temperature calibration device;

图2为样纤应变标定装置的连接示意图；Fig. 2 is the connection schematic diagram of sample fiber strain calibration device;

图3为光电复合海底电缆布里渊散射测量系统或瑞利散射测量系统测量示意图。Fig. 3 is a measurement schematic diagram of a photoelectric composite submarine cable Brillouin scattering measurement system or a Rayleigh scattering measurement system.

具体实施方式Detailed ways

下面结合附图和实施例对本发明做进一步的说明：Below in conjunction with accompanying drawing and embodiment the present invention will be further described:

1、取10米待测光电复合缆中传感光纤的样品（简称样纤），为保证10米样纤全部放入恒温槽内，在其一端熔接起连接作用的3米尾纤，将10米样纤松弛地放在恒温槽内，如图1所示，保证其处于零应变、30℃下，完成以下步骤：1. Take a 10-meter sample of the sensing fiber in the photoelectric composite cable to be tested (referred to as the sample fiber). In order to ensure that all the 10-meter sample fiber is placed in a constant temperature bath, a 3-meter pigtail that acts as a connection is welded at one end, and 10 meters The rice-like fiber is loosely placed in a constant temperature bath, as shown in Figure 1, to ensure that it is at zero strain and at 30°C, and the following steps are completed:

1）用瑞利散射测量系统测量样纤的瑞利散射信号，获得一维数组，求平均后得到P_R0；1) Use the Rayleigh scattering measurement system to measure the Rayleigh scattering signal of the sample fiber, obtain a one-dimensional array, and obtain P_R0 after averaging;

2）用布里渊散射测量系统测量样纤的布里渊散射频移和谱峰功率，得到两个一维数组，分别求平均后得到布里渊散射频移初值v_B0和谱峰功率初值P_B0；2) Use the Brillouin scattering measurement system to measure the Brillouin scattering frequency shift and spectral peak power of the sample fiber, and obtain two one-dimensional arrays, and obtain the initial value of the Brillouin scattering frequency shift v_B0 and spectral peak power after averaging Initial value P_B0 ;

3）计算C_BR =P_B0/ P_R0，此系数就是零应变、30℃下的布里渊散射谱峰功率与瑞利散射功率的比值约为2.356×10^-3，此比值视不同的布里渊散射测量系统和瑞利散射测量系统会略有不同。3) Calculate C_BR =P_B0 / P_R0 , this coefficient is the ratio of the peak power of the Brillouin scattering spectrum to the Rayleigh scattering power at zero strain and 30°C, which is about 2.356×10^-3 , and this ratio depends on different distributions A Rieouin scatterometry system and a Rayleigh scatterometry system will be slightly different.

2、利用图1所示的恒温槽对样纤进行温度标定，施加的温度点分别为10℃、20℃、30℃、40℃、50℃、60℃、70℃、80℃；利用常规的应变施加装置（悬臂梁）对样纤进行应变标定，连接示意图如图2所示，施加的应变点分别为200με、400με、600με、800με、1000με、1200με、1400με、1600με。记录不同温度和应变下的布里渊散射频移v_B和谱峰功率P_B，利用最小二乘法对布里渊散射频移和温度、布里渊散射频移和应变、布里渊谱峰相对功率和温度、布里渊谱峰相对功率和应变分别进行线性拟合，获得布里渊散射频移v_B和相对谱峰功率P_B/ P_B0与温度T和应变ε的线性关系，得到频移的温度系数C_vT、频移的应变系数C_vε、相对谱峰功率的温度系数C_PT、相对谱峰功率的应变系数C_Pε。2. Use the constant temperature tank shown in Figure 1 to calibrate the temperature of the sample fiber. The applied temperature points are 10°C, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, and 80°C; The strain application device (cantilever beam) calibrates the strain of the sample fiber. The connection diagram is shown in Figure 2. The applied strain points are 200με, 400με, 600με, 800με, 1000με, 1200με, 1400με, 1600με. Record the Brillouin scattering frequency shift v_B and spectral peak power P_B under different temperatures and strains, and use the least square method to analyze the Brillouin scattering frequency shift and temperature, Brillouin scattering frequency shift and strain, and Brillouin spectral peak The relative power and temperature, the relative power of the Brillouin spectrum peak and the strain are linearly fitted, respectively, and the linear relationship between the Brillouin scattering frequency shift v_B and the relative spectral peak power P_B / P_B0 and the temperature T and strain ε is obtained. The temperature coefficient C_vT of the frequency shift, the gauge coefficient C_vε of the frequency shift, the temperature coefficient C_PT of the relative spectral peak power, and the gauge coefficient C_Pε of the relative spectral peak power.

3、使用同一个瑞利散射测量系统对已敷设光电复合海缆中用于传感的光纤（简称传感光纤）进行一次测量，如图3所示，获得瑞利散射功率数据P_R(z)。根据布里渊散射和瑞利散射光信号在光纤中传输的衰减系数近似相等的特点，系数C_BR适合于相同条件下任意位置处的布里渊散射谱峰功率与瑞利散射功率之比；又因为瑞利散射测量系统采用的是宽谱光源，其瑞利散射信号受光纤上温度和应变的影响很小，可以忽略，即此时测量的瑞利散射功率和零应变、30℃下的功率是一样的；因此，可以获得传感光纤在零应变、30℃下的布里渊散射谱峰功率估计值P_B0(z)= C_BR×P_R(z)，其中z是某时刻散射光在传感光纤上的位置，其最大值是传感光纤长度。3. Use the same Rayleigh scattering measurement system to measure the optical fiber used for sensing in the laid photoelectric composite submarine cable (sensing optical fiber for short), as shown in Figure 3, and obtain the Rayleigh scattering power data P_R (z ). According to the characteristics that the attenuation coefficients of Brillouin scattering and Rayleigh scattering optical signals are approximately equal when transmitted in optical fibers, the coefficient C_BR is suitable for the ratio of the peak power of the Brillouin scattering spectrum to the Rayleigh scattering power at any position under the same conditions; And because the Rayleigh scattering measurement system uses a wide-spectrum light source, the Rayleigh scattering signal is slightly affected by the temperature and strain on the optical fiber and can be ignored, that is, the measured Rayleigh scattering power and zero strain at this time, the The power is the same; therefore, the estimated value of the peak power of the Brillouin scattering spectrum of the sensing fiber at zero strain and 30°C can be obtained P_B0 (z)= C_BR ×P_R (z), where z is the scattering The position of light on the sensing fiber whose maximum value is the sensing fiber length.

4、使用布里渊散射测量系统对传感光纤进行在线测量，可得到传感光纤上的布里渊散射频移分布v_B(z)和布里渊散射谱峰功率分布P_B(z)，最终计算出传感光纤上的温度和应变分布：4. Using the Brillouin scattering measurement system to measure the sensing fiber online, the Brillouin scattering frequency shift distribution v_B (z) and the Brillouin scattering spectrum peak power distribution P_B (z) on the sensing fiber can be obtained, Finally, the temperature and strain distribution on the sensing fiber is calculated:

1）计算布里渊散射频移变化量δv_B(z)=v_B(z)-v_B0；1) Calculate the variation of Brillouin scattering frequency shift δv_B (z)=v_B (z)-v_B0 ;

2）计算布里渊谱峰功率相对变化量δP_B(z)/ P_B0(z)=(P_B(z)-P_B0(z))/ P_B0(z)；2) Calculate the relative change in Brillouin spectrum peak power δP_B (z)/ P_B0 (z)=(P_B (z)-P_B0 (z))/ P_B0 (z);

3）计算传感光纤上的温度分布T(z)和应变分布ε(z)：3) Calculate the temperature distribution T(z) and strain distribution ε(z) on the sensing fiber:

$\left[\begin{array}{c}T\left(z\right)\\ \mathrm{\ϵ}\left(z\right)\end{array}\right]=\frac{1}{|C_{\mathrm{\νT}}{C}_{\mathrm{P\ϵ}}-C_{\mathrm{\ν\ϵ}}{C}_{\mathrm{PT}}|}\left[\begin{array}{cc}{C}_P& -C_{\mathrm{\ν\ϵ}}\\ -C_{\mathrm{PT}}& C_{\mathrm{\νT}}\end{array}\right]\left[\begin{array}{c}{\mathrm{\δ\ν}}_B\left(z\right)\\ \frac{\mathrm{\δ}{P}_B\left(z\right)}{P_{B0}\left(z\right)}\end{array}\right]+\left[\begin{array}{c}{T}_0\\ 0\end{array}\right]$,其中，|C_νTC_Pε-C_νεC_PT|≠0。$\left[\begin{array}{c}T\left(z\right)\\ \mathrm{\ϵ}\left(z\right)\end{array}\right]=\frac{1}{|C_{\mathrm{\νT}}{C}_{\mathrm{P\ϵ}}-C_{\mathrm{\ν\ϵ}}{C}_{\mathrm{PT}}|}\left[\begin{array}{cc}{C}_P& -C_{\mathrm{\ν\ϵ}}\\ -C_{\mathrm{PT}}& C_{\mathrm{\νT}}\end{array}\right]\left[\begin{array}{c}{\mathrm{\δ\ν}}_B\left(z\right)\\ \frac{\mathrm{\δ}{P}_B\left(z\right)}{P_{B0}\left(z\right)}\end{array}\right]+\left[\begin{array}{c}{T}_0\\ 0\end{array}\right]$ , where |C_νT C_Pε -C_νε C_PT |≠0.

通过以上公式就得到了传感光纤上的温度分布T(z)和应变分布ε(z)。The temperature distribution T(z) and the strain distribution ε(z) on the sensing fiber are obtained through the above formula.

Claims (2)

1. a temperature of having laid optoelectronic composite cable and strain measuring method simultaneously is characterized in that described method comprises:

Step 1: measure Brillouin frequency shifts initial value, spectrum peak power initial value and the Rayleigh scattering performance number of sensor fibre sample fibre in the optoelectronic composite cable, calculate the ratio of Brillouin spectrum peak power and Rayleigh scattering power;

The sample of getting sensor fibre in one section optoelectronic composite cable to be measured is fine, and the sample fibre loosely is placed in the thermostat, guarantees that it is in zero strain, T₀Under ℃, the Rayleigh scattering power with Rayleigh scattering measuring system measurement sample fibre obtains one-dimension array, obtains Rayleigh scattering power initial value P after being averaging_R0Measure the Brillouin frequency shifts of sample fibre and compose peak power with the Brillouin scattering measuring system, obtain two one-dimension array, obtain Brillouin frequency shifts initial value v after being averaging respectively_B0With spectrum peak power initial value P_B0According to C_BR=P_B0/ P_R0Calculate zero strain, T₀Brillouin spectrum peak power under ℃ and the coefficient ratio C of Rayleigh scattering power_BR

Step 2: the temperature and the coefficient of strain that obtain the temperature of the fine Brillouin frequency shifts of sensor fibre sample and the coefficient of strain, Brillouin scattering relative spectrum peak power by calibration experiment;

Utilize thermostat and strain bringing device that the sample fibre is carried out calibration experiment, the temperature that applies and strain point record the Brillouin frequency shifts v under different temperatures and the strain more than 5_BWith spectrum peak power P_B, utilize the linear fit algorithm to obtain frequency displacement v_BWith relative spectrum peak power P_B/ P_B0With the linear relationship of temperature T and strain stress, obtain the temperature coefficient C of frequency displacement respectively_VT, frequency displacement coefficient of strain C_{V ε}, relative spectrum peak power temperature coefficient C_PT, relative spectrum peak power coefficient of strain C_{P ε}

Step 3: calculate and laid the estimated value that the Brillouin of sensor fibre composes peak power distribution initial value in the optoelectronic composite cable;

Use same set of Rayleigh scattering measuring system to carry out one-shot measurement to laying the optical fiber that is used for sensing in the optoelectronic composite cable, obtain Rayleigh scattering power data P_R(z), calculate sensor fibre at zero strain, T₀The estimated value P of the Brillouin spectrum peak power distribution initial value under ℃_B0(z)=C_BR* P_R(z), wherein z is certain constantly scattered light position on sensor fibre, and its maximal value is sensor fibre length;

Step 4: the Brillouin frequency shifts of having laid sensor fibre in the optoelectronic composite cable by the real-time measurement of Brillouin scattering measuring system distributes and the power distribution of spectrum peak, calculates real time temperature and Strain Distribution on the sensor fibre;

Use the Brillouin scattering measuring system that sensor fibre is carried out on-line measurement, obtain the Brillouin frequency shifts distribution v on the sensor fibre_B(z) and Brillouin spectrum peak power distribution P_B(z), then calculate temperature and Strain Distribution on the sensor fibre:

1) calculates Brillouin frequency shifts variable quantity δ v_B(z)=v_B(z)-v_B0

2) calculate Brillouin and compose peak power relative variation δ P_B(z)/P_B0(z)=(P_B(z)-P_B0(z))/P_B0(z);

3) Temperature Distribution T (z) and the Strain Distribution ε (z) on the calculating sensor fibre:

$\left[\begin{array}{c}T\left(z\right)\\ \mathrm{\ϵ}\left(z\right)\end{array}\right]=\frac{1}{|C_{\mathrm{\νT}}{C}_{\mathrm{P\ϵ}}-C_{\mathrm{\ν\ϵ}}{C}_{\mathrm{PT}}|}\left[\begin{array}{cc}{C}_P& -C_{\mathrm{\ν\ϵ}}\\ -C_{\mathrm{PT}}& C_{\mathrm{\νT}}\end{array}\right]\left[\begin{array}{c}{\mathrm{\δ\ν}}_B\left(z\right)\\ \frac{\mathrm{\δ}{P}_B\left(z\right)}{P_{B0}\left(z\right)}\end{array}\right]+\left[\begin{array}{c}{T}_0\\ 0\end{array}\right]$, wherein, | C_{ν T}C_{P ε}-C_{ν ε}C_PT| ≠ 0.

2. method according to claim 1 is characterized in that the length of the sample of composite fiber in the described optoelectronic composite cable to be measured should be greater than 2 meters.

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