Thermal Stability of Overhead Power Transmission Lines Under Growing Short-Circuit Current Levels

Since early 2000s, an increase in the levels of short-circuit (SC) currents has been observed within the electric power systems of the Russian Federation, including 110 and 220 kV networks. This problem is especially important in the regions with high density of electric power plants and relatively short distances between network nodes. As the level of short-circuit currents increases, the issues of thermal and electrodynamic stability of the electrical equipment, and first of all, equipment which has completed its standard service life, become of primary importance. The paper discusses the issues of thermal stability of the overhead power transmission lines (OPTL), offers analysis of the calculation results related to wire heating by SC currents in more than 1000 OPTL operating at 35 – 220 kV of voltage, and provides recommendations for ensuring thermal stability of OPTL.