Research And Design Ofanti-wind Andanti-corona Bundled Conductors For UHV DC Voltage Withstand Test

Test conductors is a critical part of experimental apparatus for voltage withstand.The converter stations of800kV DC Gansu-Zhengzhou project are located inGobi-desert area of Northwest China where extremely strong wind prevails. A severeproblem arises when wind declination of extended conductor used in800kV DCwithstand test for corona suppression is so large as to constitute a great threat tocrew’s safety under local powerful wind. An innovative type of anti-corona andanti-wind24-bundled conductors for800kV DC voltage withstand test is designed totackle this problem.One major concern of design process is to select optimized parameters so that theoverall conductors possesses excellent aerodynamic characteristics in wind velocityfield while maintaining a low corona level. Based on improved charge simulationmethod, a method for calculating3D electric field of test conductors with large splitnumber and short conductor length is proposed. Reliability of the method is verifiedby comparing with IEEE’s benchmark. Furthermore, it is compared with progressiveimage method, finite element method, and Markert—Mengel method based on2Dmodel.Flow pattern and aerodynamics characteristic parameters of both a singleconductor and multi-split conductors in wind velocity field is calculated and analyzedby solving the corresponding2D Reynolds Averaged Navier-Stokes(RANS) equationof the air—bundled conductors system. The shielding and interference effect betweensub-conductors is calculated and analyzed. Based on computational fluid dynamics(CFD), the mechanism of interference effect is analyzed. By comparing with data ofWind tunnel test in literature, reliability of CFD method is verified. It concludes thatspacing ratio of multi-split conductors is a critical indicator for its flow pattern andaerodynamics characteristic parameters and that a critical spacing ratio exists wheninterference effect reaches its peak value.Finally, based on computational fluid dynamics (CFD) and charge simulationmethod (CSM), flow pattern and aerodynamics characteristic parameters of the testconductors with different design parameters in wind velocity field as well as its3Delectric field is calculated and analyzed. Aim to suppress corona and wind deviationangle, the diameter of sub-conductors, radius of spacing plate and split number of test conductors is determined considering its electric characteristic as well as mechanicalperformance. The optimized design parameters are determined of which the splitnumber is set to24, the diameter of sub-conductors is set to8mm, and the radius ofspacing plate is set to200mm. Wind deviation angle can be strongly influenced by theinterference effect between sub-conductors. At the wind speed of13.8m/s, the winddeviation angle of test conductors can be suppressed under25°and the maximumsurface voltage gradient under27kV/cm. It concludes that the anti-wind andanti-corona24-bundle conductors for800kV DC voltage withstand test possesses anexcellent electrical and mechanical performance to make sure the test procedure insafe.