Core form transformer topological duality based transient model validation for exciting current calculation within DC bias

Transformer topological duality-based transient model (TDuM) has been widely used in the electromagnetic transient (EMT) simulation to consider the impact of core non-linear features and windings arrangement on exciting current. In this study, the transformer TDuMs that specialized for geomagnetically induced current events studying were validated. After a summary of the transformer TDuMs' derivation and their parameters estimation methodologies, the numerical experiments were carried out to investigate the transformer TDuMs and their related key issues such as core's material types, loss factor of hysteresis model, linear leakage inductance, tank wall with EMT analysis software. The numerical results show a good agreement with the measured data in the field experiments with DC bias applied, which mean that using the transformer TDuM to calculate the exciting current under DC bias condition is feasible. Besides, some practical tips were proposed based on the parameters sensitivity analysis for estimating the transformer TDuMs' parameters to study the transformers' dynamics under DC bias condition.