Calculation Method for the Transient Hot-Spot Temperature Rise of Oil-Immersed Bushing in High-Speed Railway

Traction oil-immersed bushing is the only channel for connecting the high-speed railway system with the external power grid, and its transient hot spot is one of the most important factors reflecting its operation status. Since the traction load of a high-speed railway has obvious impulse characteristics, the existing calculation method for bushing given in IEEE Std C57.19-100-2012 is incompatible, because it is designed for steady electrical loads. Thus, in this article, the equivalent hot-spot temperature rise of the bushing under varying traction loads is calculated by the traction parameters (i.e., operating time
$T_{\mathrm {ot}}$
, interval time
$T_{\mathrm {it}}$
, and per unit transient traction current
$I_{\mathrm {\text {tc}}}$
). Then, the difference value of transient hot-spot temperature rise is modified by analyzing the change of transient hot-spot temperature rise under varying traction loads. Finally, a calculation method is proposed for the transient hot-spot temperature rise of the oil-immersed bushing in high-speed railway under different traction loads. A case study of a 110-kV oil-immersed bushing shows that the proposed method is speedy and accurate.