Protecting Overhead Transmission Lines (OHL) from Hot Spots Using Dynamic Line Rating (DLR) Calculations

Abstract

Overheating of the overhead transmission line (OHL) is one of the major factors that causes conductor aging due to annealing, deterioration of insulation, and hotspots. Temperature of OHL increases due to weather conditions and the loaded current on the conductors. The static line rated current (SLR) is calculated according to the supposed worst weather conditions of ambient temperature and wind speed. OHL aging due to annealing and hot spots reduces its lifetime and energy efficiency of the transmission lines. In smart grid, OHL temperature should be monitored to avoid overheating which threaten the safety and stability of the power transmission lines. In this research, thermal equations that relate the loaded current (Dynamic line rating DLR) with ambient temperature and OHL temperature are implemented. The implemented equations are used to calculate the dynamic line rated current that should be loaded on OHL without exceeding maximum permissible temperature. The proposed system is our implemented software connected to weather station and line sensor. This program was tested as simulation of real case of congested transmission network. The results show that, using our software can help to avoid overheating and hotspots by reducing the loaded current when the wind speed is lower than the supposed worst case of weather parameters. The results also show that, in real case, using our program protecting OHL from overheating and hot spots at bad weather conditions by lowering the loaded current by 58.5 % than rated current to reduce the temperature of conductor by 91.25% for certain time to protect them from overheating and hotspots.