Research On Distribution Of Ionic Current Density And Total Electric Field Of HVDC Transmission Lines In The Vicinity Of Objects

The status of China’s energy centers and power load centers are unbalanced, making the High Voltage Direct Current (HVDC) transmission projects with large capacity and long transfer distance becomes inevitable. With a lot of HVDC and UHVDC projects having been built these years in China, people pay more attention to the electromagnetic environmental problems caused by the corona discharge on DC transmission lines. The ion flow field which contains total electric field and ionic current density has become increasingly prominent. What we concerned in this paper is the ion flow field changed by the objects near the HVDC transmission lines. The study on the ion flow field in the vicinity of buildings is focus on the two-dimensional case, and few scholars have study on the three-dimensional case. This paper analyses the three-dimensional distribution of the ion flow field in the vicinity of buildings based on the two-dimensional and three-dimensional hybrid calculation methods.Firstly, the validity of the calculation program is verified compared with the experiment results. The size of the three-dimensional domain has been determined in coordination with accuracy and costs base on the program.Secondly, the three-dimensional distribution of the ion flow field in the vicinity of buildings under the±800kV UHVDC lines is exhaustively discussed, including the roof of the building and areas around the building. The range area of the building is confirmed.Thirdly, the analysis that how the width and the height of the building influence the distribution of ion flow field in the case of the building near the UHVDC transmission lines has been concluded, and it has a certain reference value instructive in the construction and design of the UHVDC projects in the future.Finally, objects and people may get high voltage in the ion flow field when the ionic current is caught by them, and this situation can cause the discharge problem. A model of human body and two models of common objects under transmission lines are built, and the discharge waveforms are also predicted.