Study on the electromagnetic environment of 1000 kV AC double-circuit transmission lines in China

The electromagnetic environment problems of three typical towers (two proposed in China, one in Japan) 1000 kV AC double-circuit transmission lines were analyzed in this paper. Successive images method was applied in calculating the conductor surface voltage gradient and power frequency electric field intensity (EFI) at the level of 1 m above the ground surface. Corona loss (CL), radio interference (RI) level and audible noise (AN) were calculated and the values at typical altitudes were calculated by using empirical formulas respectively. The minimum distance of the lowest phase conductor to the ground, corridor width (CW), RI level and AN were discussed according to the proposed electromagnetic environment control criteria in China. The correlation of a linear function between the RI level and the average maximum bundle gradient was discussed. CL, RI and AN variation with the bundle spacing were also discussed. Calculation and discussion results show that the two typical tower lines can satisfy electromagnetic environment control criteria at different altitudes by selecting suitable line parameters.