Determination of a New Model for Investigating Ultra-Saturation Phenomenon during the Enegization of the Loaded Three-Phase Power Transformer and Its Effect on Differential Protection

One of the mal-operation of the power transformer differential protection that may occur during the energization of a loaded power transformer is the ultra-saturation phenomenon. In this paper, a new model to study the ultra-saturation phenomenon during the energizaton of a loaded three-phase power transformer is presented and its effect on the differential protection of the power transformer is considered. For modeling of the ultra-saturation phenomenon, the nonlinear characteristic of the transformer core and the saturation effect of current transformers are considered. It is assumed that the load of the power transformer is a resistive and an inductive load. The mal-operation of the differential protection depends on a variety of factors the most important parameters of which are inception angle and residual flux. In this paper the parameters mentioned will study in different cases. In this paper, simulation is done by MATLAB program.