A METHOD FOR MODELING NONLINEAR CORE CHARACTERISTICS OF TRANSFORMERS DURING TRANSIENTS

An EHV transformer's insulation system must be designed to withstand s tresses generated during transient events. Computer models are employe d for predetermination of these stresses. The lack of accurate and con sistent computer models for use by both utilities and manufacturers, i s felt to contribute to the relatively high failure rate of EHV transf ormers. This paper develops a detailed nonlinear transformer model and a solution method that improves the accuracy with which the effect of the nonlinear characteristic of the magnetic core during transients c an be predicted. This model is based on linearization of the core's sa turable characteristic during solution time intervals. This paper desc ribes a nonlinear, single phase, detailed transformer model and its ve rification against measured data.