Icing detection method of 500 kV overhead ground wire with tangent tower under special terrain based on vertical tension measurement technology

The operation reliability of the power grid and the stability of social production are seriously threatened by the icing of the overhead line. The equivalent ice thickness (EIT) is to convert different densities and shapes of ice into the uniform annular ice with density of 0.9 g/cm3. Although many methods for calculating EIT of transmission line conductors have been proposed, there are lack an effective monitoring method of EIT for 500 kV ground wire with tangent tower under the special terrain where “the virtual lowest point” of the ground wire appears in the condition of large height difference. Therefore, a calculation method of EIT for 500 kV ground wire with tangent tower under the special terrain based on vertical tension measurement technology is proposed. That is the iterative method is used to preset different EITs. Then the calculated vertical tension under the preset values are solved by the established ground wire state equation and vertical tension equation. The EIT can be obtained when the calculated vertical tension is equal to the measured vertical tension. The comparison between the artificial observed EIT and the calculated EIT is carried out for two practical cases of 500 kV ground wire in the mountainous area of southern China. The results show that the absolute error is less than 2 mm, which verify the two values are in strong agreement. The corresponding finite element simulation models are established. A comparative study between the simulated EIT and the calculated EIT is carried out. The results show that the relative error is less than ±10% under severe icing from 10 mm to 30 mm and the absolute error is less than 1 mm under mild icing of 5 mm, which verify the two values are highly consistent. Finally, the application effect of this method in practical cases is analyzed.