Radial-strength of Transformer Windings Considering the Temperature Effect under Reclosing Short-circuit Conditions

With the rapid growth of capacity in power systems, transformer failure caused by short circuits has become the primary problem in maintaining operational reliability. In addition, with automatic reclosing, transformers may suffer multiple short-circuit impacts within a short time interval, thereby challenging their short-circuit stability. In this study, a comprehensive analysis of the radial strength under reclosing short-circuit conditions is performed on a 50 MV·A transformer considering the influence of temperature. First, a fault model of the power transformer is established to calculate the short-circuit currents under the initial short circuit and reclosing conditions. Three-dimensional (3D) finite element analyses of the short-circuit forces acting on the transformer winding with the initial and reclosing short circuits are then conducted. Finally, the influence of temperature on the windings after reclosing is calculated. The stress characteristics of the windings are calculated by considering the effects of temperature on the self-adhesive transposition wire.