Predicting conductor sag of power lines in a new model of Dynamic Line Rating

Abstract

Dynamic Line Rating is an effective way of uprating transmission lines in a cost efficient way, without reconductoring old lines, or building new ones. Uprating of equipment found in power systems has always been an issue. Having higher ampacity rates over a power line due to DLR, increased thermal stress occurs not only on the conductors, but on insulators, and on other pieces of equipment as well. Increased ampacity resulting in increased temperature of conductors brings about an increase in sag, thus electrical clearance might be violated with higher probability. A new method of calculating dynamic line rating is being developed in the High Voltage Laboratory of Budapest University of Technology and Economics (HVL-BUTE), where risks of using Dynamic Line Rating are also being researched. The new model aims at predicting dynamic line rating, which involves assessing upcoming risks caused by higher ampere capacity.[3] It also involves in the calculations the thermal inertia of conductors, in order to exploit the capabilities of the line more efficiently. The model estimates conductor temperature for the upcoming minutes, based on forecasted ambient parameters and current loading of the line, which makes it possible to foretell line sag, taking into account other factors like mechanical loading or ageing of conductors.