ThermOHL

Temperature estimation of overhead line conductors is an important topic for TSOs for technical, economic, and safety-related reasons (DLR/ampacity, sag management ...). It depends on several factors, mainly transit, weather and the conductor properties. ThermOHL is a python package to compute temperature and/or ampacity in overhead line conductors.

Features

The temperature of a conductor is estimated by solving a heat equation which describes how temperature evolves over time, taking into account different power terms that either heat or cold the conductor (see next picture from CIGRE[1]).

Two heat equations (a more complete, third one is under development) are available:

• one with a single temperature for the cable;
• another with three temperatures (core, average and surface temperature) for more precise computations.

Each of these equations can be used with a set of pre-coded power terms from the literature :

• one using CIGRE recommendations[1];
• one using the IEEE standard[2];
• two others from RTE departments.

Solvers derivated from heat equations can compute steady-state temperature or ampacity, and transient temperature. The set of parameter required depends on the power terms used, and default values are provided.

References

• [1] Stephen et al., Thermal behaviour of overhead conductors. CIGRE, Study committee 22, working group 12, 2002. https://e-cigre.org/publications/detail/207-thermal-behaviour-of-overhead-conductors.html.
• [2] IEEE, Standard for Calculating the Current-Temperature Relationship of Bare Overhead Conductors. IEEE Std 738–2012 (Revision of IEEE Std 738–2006, Incorporates IEEE Std 738–2012 Cor 1–2013), 2013. https://doi.org/10.1109/IEEESTD.2013.6692858.