基于分布式光纤应变和温度传感的光纤复合海底电缆状态监测方法研究

发布时间：2018-01-07 01:22

本文关键词：基于分布式光纤应变和温度传感的光纤复合海底电缆状态监测方法研究　出处：《华北电力大学》2015年博士论文　论文类型：学位论文

【摘要】：海底电缆是保证岛屿和海上石油平台供电、海上风电场输电的重要纽带,实时获取运行状态,确保其安全稳定运行,对保障社会与经济发展意义重大。针对光纤复合海底电缆敷设环境特殊、状态获取困难的问题,本文提出利用分布式光纤应变和温度传感技术进行状态监测的方法,研究了监测系统参数配置方法、应变和温度区分的工程方法、海底电缆与光纤的应变和温度关系建立方法、机械和电气故障特征提取、检测与诊断方法等内容,旨在为海底电缆状态监测提供理论和技术支撑。本文主要研究成果如下：1.提出了针对测量精度和实时性的系统参数综合配置方法,建立了系统参数与测量精度和实时性的关系方程；提出了优于传统OTDR的传感光路关键点定位方法,利用BOTDR测量的光纤布里渊频移实现了光路连接点和特征点的准确定位；提出了利用金属管线性热膨胀特性进行光纤布里渊散射应变和温度系数同时标定的新方法。2.提出了利用试探法确定布里渊谱峰功率初始值,利用归一化法克服传感系统中乘性噪声导致的测量误差,利用谱宽变化消除应变和温度突变点处谱峰功率异常峰值等方法,根据BOTDR测量的布里渊频移和谱峰功率实现了光纤应变和温度的区分测量；另外,利用单模光纤ROTDR仅对温度敏感的特性补偿布里渊频移对应变和温度的交叉敏感,实现了现场光纤复合海底电缆中单模光纤应变和温度的区分测量；最终解决了监测现场传感光纤应变和温度无法区分测量的难题。3.对海底电缆卷绕、直线拉伸和张力弯曲等常见机械试验进行了理论分析,建立了直线拉伸时海底电缆与光纤的应变关系方程；构建了直线拉伸的有限元模型,进行了实体试验,求解与试验结果证明了所建方程的正确性；基于温度场理论,构建了海底电缆稳态和暂态热路模型,建立了不包含环境热阻、热容和温度的海底电缆与光纤的温度关系方程；利用有限元法建立了海底电缆、光纤及周围环境的稳态热力学模型,并建立了三者的温度关系,已知任意两个变量的温度即可求出第三个变量的温度；提出了利用传感光纤应变和温度计算海底电缆应变和温度的方法,为缆体应变和温度信息的获取提供了理论支持。4.建立了锚砸和钩挂的动力学有限元模型及接地短路和漏电的有限元电热耦合模型,提取了故障发生后的应变和温度分布数据,得出了不同故障时应变和温度的空间分布与时间变化特征,克服了实体试验实施难度大、数据提取困难的难题,为故障检测和诊断提供了有效的数据支持。5.提出了基于分布式光纤应变和温度分布的海底电缆故障检测和诊断方法。利用归一化方法消除了系统噪声和环境温度对故障检测的影响,结合超阈值数据点个数和连续超阈值次数进行故障检测和报警,降低了误报率；利用二阶八尺度coif小波对奇异点敏感的特点准确发现故障位置,利用时频多分辨特点准确判断故障类型,为工程应用提供了有效可行的方法。
[Abstract]:Submarine cable is to ensure the supply of islands and offshore oil platform, an important link of offshore wind power transmission, real-time operation state, to ensure the safe and stable operation, to ensure the great significance of social and economic development. In view of the fiber composite submarine cable laying special environment, difficult problem of state acquisition, this paper puts forward a new method of condition monitoring using distributed optical fiber strain and temperature sensing technology on the monitoring system parameter configuration method, engineering method of strain and temperature sensitive, establishing method of submarine cable and optical fiber strain and temperature, mechanical and electrical fault feature extraction, content detection and diagnosis methods, in order to provide theoretical and technical support for the submarine cable condition monitoring. The main research results of this paper are as follows: 1. we propose the comprehensive configuration method of system parameter measurement precision and real-time measurement, and establish the system parameters The relationship between quantity equation accuracy and real-time point positioning method is proposed; the key sensing optical path is superior to the traditional OTDR, shift to realize the accurate positioning of optical connection points and feature points using the optical fiber Brillouin frequency BOTDR measurement is proposed by using metal tube; new method of linear thermal expansion characteristics and calibration of optical fiber Brillouin scattering of strain and temperature the coefficient of.2. is proposed by using heuristics to determine the Brillouin spectrum peak power initial value, overcome the measurement error caused by the multiplicative noise sensing system using normalization method, the spectral width change eliminates the strain and temperature discontinuity point of peak power abnormal peak method based on Brillouin frequency shift and BOTDR measurement peak power can be distinguished the measurement of optical fiber strain and temperature; in addition, the use of single mode fiber ROTDR only on the characteristics of Brillouin frequency shift compensation temperature sensitive cross sensitivity of strain and temperature, solid The simultaneous measurement of strain and temperature field of single-mode fiber optical fiber composite cable in the final settlement; field monitoring of optical fiber strain sensor and temperature measurement cannot distinguish the problem of.3. winding of submarine cable line, stretching and bending of common mechanical test were analyzed, strain relationship of submarine cable and fiber established line stretching when; constructed the finite element model of linear stretching, physical test, the correctness of the calculation and test results show that the mathematical equation; temperature field based on the theory of construction of the submarine cable steady and transient thermal circuit model is established, including environmental resistance, submarine cable and optical fiber temperature equation between heat capacity and temperature the establishment of the submarine cable; using the finite element method, the fiber and the surrounding environment and the establishment of a steady-state thermodynamic model, the temperature of the relationship between the three, any two known The temperature can be variable for each of third variable temperature; calculation method is put forward by submarine cable strain and temperature sensing fiber strain and temperature, provides electric coupling finite element model theory support.4. established a dynamic finite element model of anchor smash and hook and grounding short circuit and leakage for cable body strain and temperature information, extracting the fault occurred after the strain and temperature distribution data, obtains the varying characteristics of the spatial distribution of strain and temperature and time of different faults, overcome the entity test implementation is difficult, the difficulty of data extraction, provides effective data support.5. proposed distributed optical fiber strain and cable fault the temperature distribution of the detection and diagnosis method based on fault detection and diagnosis. To eliminate the influence of system noise and environmental temperature on the fault detection using the normalization method, combined with super The threshold number of data points and the number of continuous super threshold fault detection and alarm, reduce the rate of false positives; using two order eight scale coif wavelet for singularity sensitive characteristics accurately detect the fault location, using time-frequency multiresolution characteristics accurately determine the fault type, the method is effective and feasible to provide for engineering application.

【学位授予单位】：华北电力大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：P756.1;P715.5

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