Analysis of half-wavelength transmission lines with simulation of corona losses

The growing interest in very-long-distance transmission (2-3000 km) and the state of the art of half-wavelength transmission lines are briefly discussed. A model for the numerical simulation of corona losses at high electric gradients is proposed. Then an analysis is made of the steady-state and transient operation of an 800 kV, 60 Hz, 2500 km double circuit line. Results show that corona losses drastically limit the sustained overvoltages, but also place a limit on transmissible power and can affect transient stability. Possible schemes for interconnection of two half-wavelength lines at intermediate switching stations are also examined in order to attain acceptable system reliability