Discharge Test and Vertical Safe Distance of ±800kV UHVDC Line and 500kV Line in Crossing Area

Abstract:
UHV lines crossing over other lines is the situation that often occurs in the construction of ultra-high voltage line engineering, UHV lines above the crossing section can play the role of lightning shielding equivalent to the ground wire on the line under crossing sections. The vertical safe distance between lines in the crossing area needs to be obtained through the external insulation test. In this paper, a phase-to-phase gap discharge test platform is built to simulate the situation of a ±800kV UHVDC line crossing the 500kV AC line below. The study of the vertical safe distance between UHV lines and 500kV lines crossed by the ground line was carried out. The influencing factors of the phase-to-phase discharge voltage of the cross-crossing line were analyzed. The results show that the smaller the crossing angle, the smaller the discharge voltage of the air gap. By fitting the discharge characteristics of the phase-to-phase discharge voltage and air gap distance, considering the maximum voltage and safety margin, it is concluded that the vertical safety distance between ± 800kV and the 500kV line below is 12.8m.