Real-Time Dynamic Thermal Rating Method to Uprate the Ampacity of Overhead Transmission Lines: A Case Study

Traditionally, Static Thermal Rating (STR) calculates current carrying capacity based on “Worst case weather conditions”, which is used by most of the utilities around the world including Sri Lanka. Assumptions made in the STR calculations may reduce the actual line capacity whenever real weather conditions are less stressful. However, the smart-grid technology based Real Time dynamic Thermal Rating (RTTR) allows to utilize the overhead line conductors by increasing the current carrying capacity of the line based on real time weather data. The identification of critical span to ensure the minimum electrical clearance is the major consideration to ensure the safety of the people and equipment when applying RTTR method. This paper presents a method to introduce real time thermal rating to overhead transmission lines in Sri Lanka. Current rating of lines is calculated using real time weather data. In here, the selected line sections have been analysed using PLSCADD software with RTTR design. This novel methodology can be used by system operators to analyse weather based current ratings for the transmission network in future.