Comparative Study of Single-phase Shell & Core Type Transformers in GIC Temperature Rise Effect

Abstract

Geomagnetically induced currents (GICs) flowing through transformers may cause temperature rise which could result in permanent damage. As the single-phase-set transformers are widely used in the bulk power transmission, this paper investigates the temperature rise effect both in shell type transformers and core type transformers. Based on the designing parameters of the 500kV single-phase shell type and core type transformer, a 3D finite element model including the transformer iron core, tank and supporting parts has been established, so that the temperature rises in the iron cores and supporting parts are all taken into account. Through calculation with different values of GIC excitations, the different temperature rise characteristics between shell transformer and core transformer are investigated. The simulation results of the temperature rise at different positions in the supporting parts can provide references for the designing of Chinese UHV (ultrahigh voltage) transformers to mitigate the temperature rise due to DC bias.