Evaluation of Sensors for the Dynamic Rating of Overhead Lines

Inhalt:
An overhead line’s actual available ampacity can be determined on the basis of the actual weather conditions, whereby the maximum permissible conductor temperature must not be exceeded. This is referred to as “Dynamic Line Rating”. To ensure compliance with the temperature limits, special sensors are available that can be attached directly to overhead line conductors. As these sensors have to operate for a long time without maintenance in a very harsh environment, the performance of such systems was investigated in laboratory tests. For example, the accuracy of the temperature and current measurement functions up to 1000 A were analysed in long-term tests using a realistic test setup with overhead line conductors. Other laboratory tests were dedicated to investigating the robustness of DLR sensors against the effects of impulse voltages (lightning strikes in the immediate vicinity) and against the effects of high impulse currents (shortcircuit currents up to 70 kA). The investigations showed that temperature measurement directly on the OHL conductor in particular is subject to numerous influences. Furthermore, the tests for robustness against electromagnetic influences also revealed potential for improvement. One example of this is the irreversible failure of sensors due to moderate short-circuit currents. Overall, this contribution aims to show how the optimization of the utilization of overhead lines can be supported with the help of suitable sensors. In addition, the limitations of such systems discovered in laboratory tests and the resulting technical challenges are also discussed. Ultimately, the aim is to contribute to the technical refinement of DLR systems, thereby optimizing the utilization of existing infrastructure and further increasing the security of supply.