Aiming at extra high voltage (EHV) transmission lines with crossing

three dimensional space electromagnetic environment of EHV crossing lines is studied by finite element method

and the influence of different phase sequence arrangement and different crossing angles on the space electromagnetic environment is analyzed. For the transmission lines in plan or having been built

chaotic particle swarm optimization algorithm with variable parameters is introduced when electromagnetic environment exceeds the standard in the target area

and the optimal erecting position of shielding lines is searched to make the best shielding effect

thus

the optimal shielding of the target area is achieved.