distributed fiber-optic temperature sensing for Temperature monitoring of power cables

The number of power cables, oil and gas pipelines, bridges and tunnels, large buildings, and urban comprehensive pipe galleries is rapidly increasing. Real time distributed temperature monitoring of power cables can timely detect local temperature anomalies, analyze insulation problems of the line, prevent cable fires, and ensure the continuous and safe operation of cables. In addition, it can also provide assistance for calculating steady-state current carrying capacity. The commonly used temperature measurement methods for power cables include temperature sensing cables, point temperature sensors, and infrared temperature measurement. Compared with traditional methods, distributed fiber optic temperature measurement technology has advantages such as long detection distance, anti electromagnetic interference, variable appearance, intrinsic safety, easy installation, and long-term use, making it a development trend for power cable temperature measurement.

In response to the issues of measurement distance and spatial resolution in distributed fiber optic temperature measurement technology, a time-division multiplexing distributed fiber optic temperature measurement system based on Raman scattering effect is used for online temperature monitoring of power cables. Through time-division multiplexing data fusion, the sensing distance is extended and the spatial resolution is improved, and power cables can be monitored in zones. Establishing a distributed fiber optic sensing network has practical applications in temperature detection of power cables.

The principle of distributed fiber optic temperature sensors includes fiber optic scattering principle and optical time-domain reflection positioning technology. FJINNO has designed a time-division multiplexing distributed fiber optic temperature measurement scheme based on Raman scattering effect. Key components such as pulse laser, wavelength division multiplexer, avalanche photoelectric amplifier have been analyzed and studied, and device selection design has been carried out. Embedded hardware with a microprocessor as the core communicates with the upper computer through protocol, and reference temperature collection and fiber channel switching have been achieved under the control of the upper computer; The upper computer software was developed using the platform, which achieved functions such as measurement channel switching control, scattering signal acquisition, signal wavelet denoising algorithm processing, real-time dynamic temperature curve drawing, and temperature database establishment; Finally, the DTS system was tested and the integration of the prototype was completed. The performance parameters achieved were: temperature measurement range of -25 ℃ to 200 ℃, temperature measurement accuracy of ± 1 ℃, single channel positioning accuracy of ± 1m, and single channel measurement range of 10km. By time division multiplexing data fitting, the measurement distance has been improved, allowing the system to adapt to more complex working conditions. We conducted temperature field simulation experiments on power cables and DTS detection simulation experiments on cable faults, and the results showed that the prototype meets the requirements of power cable fault monitoring.

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