Analysis of Influencing Factors for Parameter Calculation of Double-Circuit Parallel Transmission Line Based on Electromagnetic Environment and its Effect on State Estimation

With the continuous development of urban power grid, the layout of urban power transmission lines has become more and more compact. Double-circuit parallel transmission line emerges under this circumstance. However, the distance between the transmission lines is greatly reduced due to the parallel connection of the same rod, which may affect the actual parameter evaluation of the transmission lines and lead to the deviation of the steady-state calculation results of the power system. Therefore, more accurate estimation for the line parameters is necessary. In this paper, a magnetic field simulation for the transmission line has been used to analyze the difference between the actual result and the empirical formula. The empirical formula is not suitable for the differential calculation of different distance and different sag size, and the influence of asymmetric line parameters has been analyzed. Ansys finite element simulation has also been used to prove the validity of the magnetic field simulation, the theoretical calculation has been proved to be basically accurate. In the urban distribution network with complex working conditions, the line parameters need to be refined estimation, and the empirical formulas may affect the accuracy of the steady-state calculation results.