特高压直流控制保护系统相位光时域反射仪信噪比提升方法  

SNR Improvement Methods for Phase-Sensitive Optical Time-Domain Reflectometer for UHV DC Control and Protection System

作　　者：阮峻[1] 朱志俊 孙豪 朱一峰[1] 徐宛丽 吕涛[2] 吴宝锋[2] 孙小菡[2] Ruan Jun;Zhu Zhijun;Sun Hao;Zhu Yifeng;Xu Wanli;Lu Tao;Wu Baofeng;Sun Xiaohan(Kunming Bureau,CSG EHV Power Transmission Company,Kunming 650300,Yunnan,China;National Research Center for Optical Sensing/Communications Integrated Networking,Southeast University,Nanjing 210096,Jiangsu,China)

机构地区：[1]中国南方电网超高压输电公司昆明局,云南昆明650300 [2]东南大学光传感/通信综合网络国家地方联合工程研究中心,江苏南京210096

出　　处：《中国激光》2022年第9期127-134,共8页Chinese Journal of Lasers

基　　金：国家自然科学基金(61271206);南方电网2019年科技服务项目(2019-41)。

摘　　要：分析了由特高压直流输电控制保护工程系统相位光时域反射仪(Φ-OTDR)测得光缆沿线时域、频域信号的分布规律,提出了信号时域乘法短时过双电平率与频域分段频带均方根误差(RSMD)综合算法,编制了综合算法程序,开展了工程实验。当光缆链路在2.3,5.0,10.8,16.0km处存在微弱故障时,利用乘法短时过双电平率法可使得系统信噪比(SNR)分别提高到9.41dB、9.02dB、7.60dB、3.50dB。当光缆链路信号频带内分段数为8时,系统SNR可进一步提升,且频带RSMD峰值可突出微弱故障位置,与实际情况差异小。所提方法的光缆链路微弱故障定位精度达到±2m,不仅提升了工程系统的SNR,还解决了难以辨识光缆链路微弱故障的问题。Objective Many optical-fiber cables with properties,such as control,DC measurement,and lightning protection are applied in the UHV DC control and protection system,forming an optical cable link with optical cable connectors.In actual operation,the weak failure of optical cable links brings great risks to the system.Phase-sensitive optical time-domain reflectometry(Φ-OTDR)detects and locates the faults along the optical cable link.However,when Φ-OTDR is used in an actual UHV DC engineering system,the site environment greatly impacts the optical cable link,resulting in a very low signal-to-noise ratio(SNR)of the received signal at the system terminal.So,the weak fault signal is submerged in noise and difficult to distinguish.In this study,we explore the signal characteristics of the actual engineering system and find ways to reduce noise,optimize the denoising algorithm,and improve SNR,to achieve accurate positioning of weak faults in the system.Methods Φ-OTDR-based test environment is established in the UHV DC control and protection engineering system.We analyze the data characteristics of the optical cable link obtained using the high-speed data acquisition card at the bottom of Φ-OTDR terminal equipment after repeated experiments.Results show that the statistical characteristics of time-domain characteristic parameters of fault signal meet a certain law,different from the statistical law of noise signal.Also,the distribution of noise spectrum and fault signal spectrum density of the optical cable link is different.The former has uniform performance and the latter concentrates on the main vibration frequency with large dispersions.Thus,given the frequency domain-segmented band root mean square difference(RSMD)and algorithm flow,we propose a synthesis algorithm of time-domain multiplication short-time over dual-level rate.Results and Discussions The comprehensive algorithm program and experiment are compiled and conducted in the UHV DC control and protection engineering system.Given a weak fault at 2.3 km of o

关 键 词：光纤光学 特高压 直流控制保护 相位光时域反射仪(Φ-OTDR) 信噪比(SNR) 

分 类 号：O436[机械工程—光学工程]