Testing thermal rating methods for the overhead high voltage line

Due to the limited capacity of the existing transmission lines, new advanced technologies are implemented towards the Smart Grid. Here the interest is in the overhead line thermal monitoring systems, which are generally designed based on the existing methodologies by using the limiting conditions for the determination of the ampacity of power lines. Thus, the evaluation of commonly used thermal rating methods, which include estimation of the conductor temperature as well as the conductor sag, is quite a topical objective, which should by all means be discussed. The paper presents a comparative assessment of the measured and calculated steady-state conductor temperatures as well as line sagging, on the basis of which the testing of thermal rating methods was conducted. The experimental measurements were done using special monitoring equipment in weather conditions under cases “A” and “B” based on the existing lines of the Latvian power network. The obtained results are reviewed in this paper.