Principles and Applications of Distributed Fiber Optical Temperature Sensing-INNO

Detección distribuida de temperatura por fibra óptica (EDE) is an advanced temperature monitoring technology that utilizes optical fibers as temperature sensitive components and signal transmission media to achieve continuous and real-time monitoring of temperature distribution over long distances and large ranges. DTS systems are typically based on the principle of optical time domain reflectometry (OTDR) and the Raman scattering effect of optical fibers, and obtain temperature distribution information along the fiber by analyzing the intensity changes of backward Raman scattering light in the fiber.

1、The main components of DTS system

fuente de luz
Laser: High power pulsed lasers such as Nd: YAG lasers or Erbium doped fiber amplifier (EDFA) lasers are commonly used. The pulse light signal emitted by the laser is transmitted to the measured area through optical fiber.
Fibra optica
Sensing fiber: used for transmitting optical signals and serving as a temperature sensitive component. Common sensing fibers include single-mode fibers and multi-mode fibers. Single mode fiber is widely used due to its low loss and high resolution.
detector
Fotodetector: used to detect backscattered Raman light returning from optical fibers. The commonly used photodetectors include photomultiplier tubes (PMT) and avalanche photodiodes (APD).
unidad de procesamiento de señal
Data acquisition card: used to collect electrical signals output by photodetectors and convert them into digital signals.
Signal processor: processes the collected digital signals and extracts temperature information. Common signal processing algorithms include Fourier transform, wavelet transform, etc..
software system
Data analysis software: used to display and analyze temperature distribution data, generar curvas de temperatura y gráficos de distribución de temperatura. Los sistemas de software suelen tener almacenamiento de datos., funciones de alarma, y capacidades de monitoreo remoto.
El principio de funcionamiento del sistema DTS.
Principio de la reflectometría óptica en el dominio del tiempo (OTDR)
La señal de luz pulsada emitida por el láser se propaga a lo largo de la fibra óptica., y cuando encuentra puntos desiguales o caras extremas en la fibra, producirá luz retrodispersada. Midiendo el tiempo de retorno y la intensidad de la luz retrodispersada., Se puede determinar la distancia de propagación y la posición de la señal óptica en la fibra..
dispersión raman
Cuando las señales ópticas se propagan en fibras ópticas., Se producen varios tipos de dispersión., incluyendo la dispersión de Rayleigh, dispersión de brillo, y dispersión Raman. La intensidad de la luz de dispersión Raman depende de la temperatura.. La dispersión Raman se divide en dispersión Stokes y dispersión Anti Stokes.. The intensity of anti Stokes scattering light increases with temperature, while the intensity of Stokes scattering light does not change significantly with temperature. By measuring the intensity ratio of anti Stokes scattering light to Stokes scattering light, the temperature at each point along the fiber can be calculated.

2、Application scenarios of DTS system

Sistema de energía
Monitoreo de temperatura de cables: In high-voltage cables and cable trenches, DTS system can monitor the temperature distribution of cables in real time, detect overheating problems in a timely manner, and prevent cable damage and fire accidents.
Substation temperature monitoring: In the substation, the DTS system can monitor the temperature of equipment such as transformers and switchgear to ensure the safe operation of the equipment.
Oil and gas industry
Oil pipeline monitoring: In long-distance oil pipelines, the DTS system can monitor the temperature distribution of the pipeline in real time, detect leakage points and temperature anomalies in a timely manner, and prevent environmental pollution and economic losses.
Oil well temperature monitoring: In oil wells, DTS systems can monitor the temperature distribution underground, providing data support for oil extraction.
Architecture and Infrastructure
Bridge temperature monitoring: In large bridges, DTS systems can monitor the temperature distribution of the bridge body, evaluate the health status of the bridge, and promptly detect potential safety hazards.
Tunnel temperature monitoring: In tunnels, DTS systems can monitor the temperature distribution inside the tunnel to ensure its safe operation.
protección ambiental
Soil temperature monitoring: In agricultural and ecological research, DTS systems can monitor soil temperature distribution, provide guidance for agricultural production, and study soil microbial activity and nutrient transformation.
Water temperature monitoring: In rivers, lagos, y océanos, DTS systems can monitor the temperature distribution of water bodies and study the impacts of water ecosystems and climate change.
fire safety
Warehouse temperature monitoring: In large warehouses, DTS systems can monitor the temperature distribution inside the warehouse, detect fire hazards in a timely manner, and prevent fire accidents.
Tunnel fire monitoring: In tunnels, DTS systems can monitor the temperature distribution inside the tunnel in real time, detect fires in a timely manner, and activate the fire protection system.

3、Advantages of DTS system

Monitoreo a larga distancia: The DTS system can achieve temperature monitoring for up to tens of kilometers, suitable for large-scale, long-distance temperature monitoring scenarios.
Resolución alta: DTS systems can provide temperature distribution data with high spatial resolution, typically up to several meters or even shorter.
Monitoreo en tiempo real: The DTS system can achieve real-time and continuous temperature monitoring, and detect temperature anomalies in a timely manner.
Anti interferencia electromagnética: Optical fibers have good anti electromagnetic interference capabilities and are suitable for temperature monitoring in strong electromagnetic environments.
Fácil instalación: The installation and maintenance of DTS system are relatively simple and cost-effective.

4、Limitations of DTS system

Costo: Although the unit cost of DTS system decreases with the increase of monitoring distance, the initial investment cost is still relatively high.
Accuracy limitation: The temperature measurement accuracy of DTS system is affected by various factors, such as fiber quality, environmental temperature changes, external interference, etc..
Complex data processing: DTS systems require complex signal processing algorithms and high-performance computer systems to process large amounts of data.
summary
El Detección distribuida de temperatura por fibra óptica (EDE) system is an advanced temperature monitoring technology that utilizes the Raman scattering effect and optical time domain reflection principle of optical fibers to achieve continuous and real-time monitoring of temperature distribution over long distances and large ranges. DTS system has a wide range of applications in the fields of power system, industria del petróleo y el gas, construction and infrastructure, protección ambiental, fire safety, etc.. It has advantages such as long-distance monitoring, resolución alta, monitoreo en tiempo real, antiinterferencia electromagnética, y fácil instalación. Sin embargo, DTS systems also have limitations such as high cost, limitaciones de precisión, and complex data processing.