Research On Electromagnetic Environment Of HVDC Transmission Line With Heterogeneous Conductor Bundle

In order to meet the continuous growth of power demand in our country,the construction of UHV power grids is an important way to realize the optimal allocation of resources.Multi-bundled sub-conductors,adjust the wire height and distance between poles are the main way to optimize the electromagnetic environment.Reasonable arrangement of bundled conductors can reduce field strength on the conductor surface,thereby reducing radio interference level,audible noise and corona loss.At present,most of bundled conductors in China and abroad are arranged with the sub-conductors in a circle with equal spacing.First of all,this paper detailed studying the design scheme of three ellipse sub-conductors,the field strength,the balance between the sub-conductors,the audible noise,the radio interference and the ground composite electric field have been analyzed and calculated.Compared with the calculation results of regular polygonal conductor arrangement in regular circle,It is concluded that the arrangement of the bundled conductors with the major axis perpendicular to the ground is the optimal solution.Then,combined with the actual bundled conductors in HVDC transmission line and researched the different arrangement of bundled conductors,A method of optimal arrangement of bundled conductor for HVDC transmission is proposed.When the sub-conductors are symmetrically distributed on an ellipse with its long axis perpendicular to ground,an optimal arrangement is obtained with a minimum ratio of the maximum to the minimum sub-conductor surface field strength,and the most balanced sub-conductor surface field intensity distribution is achieved.Optimal range of the long and short axis of the ellipse is given when the field strength of the 8 or 6 or 4 bundled conductors are optimal.Finally,proposed a method for reducing the field strength of conductor surface of HVDC bundled conductors by using large-sectional conductors based on the study of conventional model.large-sectional conductors are partly adopted in HVDC transmission lines and are symmetrically used on two maximum field strength sub-conductors or the bottom sub-conductors in the same symmetrical polarities.This conductors configuration method can reduce the field strength of conductor surface of the HVDC transmission line,then reduce the material cost under the same conditions and the corona discharge extent of the transmission line and optimize the balance of the field strength of each sub-conductors.The results of this study provide a reference for studying the field strength and optimize electromagnetic environment of HVDC transmission lines.