AP Sensing Delivers Monitoring Solution to French Electricity Transmission System Operator

AP Sensing recently deployed our technology to monitor 225 kV underground power cable link located in the west of France for Réseau de Transport d’Électricité (RTE), the French electricity transmission system operator. The link is approximately 39 km long and monitored for Third Party Intrusion (TPI) activities plus cable faults using our Distributed Acoustic Sensing (DAS) system, as well as hotspots using our Distributed Temperature Sensing (DTS) system. Additionally, SmartVision software with a MapView module is utilized in order to visualize the power link, corresponding temperature profiles, and any DTS/DAS alarms in a single map based on the GPS coordinates of the power link.

Systems & Installation

One, one-channel 5200A DAS system with a measuring range of 50 km is in use, as well as a one-channel N4525A DTS system with a measuring range of 50 km. Both systems are connected to a single mode fiber each within the fiber optic sensing cable, which is installed in a cable duct.

The power link installation is surrounded by frequent agricultural activities that pose no harm to the cable. To mitigate the risk of increased false alarms from these activities, similar events were simulated to test the system based on soil mixing and harvesting agricultural machinery.

Detection Principles

The detection principle in this project uses both classic detection and time-space gradient detection. In classic detection, the maximum temperature threshold and maximum temperature difference to the average zone temperature are used for hotspot detection. This is easily configured, but there are several limitations for small hotspots.

Time-space gradient detection or “smart monitoring” requires an analysis of the temperature history and an analysis of the ambient temperature for each position. The results are then combined mathematically to determine a measure of unusual behavior, and an alarm is triggered when a certain threshold is exceeded.

With time-space gradient detection, a higher sensitivity is achieved than with classic detection, so that much smaller changes in temperature can be detected. To determine the alarm threshold, the data is recorded and analyzed over several weeks.

After project commissioning and testing, AP Sensing conducted online training for RTE personnel, followed by on-site training. The customer was very satisfied with the project deliverables and training.

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Find out more about AP Sensing's Power Cable Monitoring solution here.