DefinePK

Abstract

In a transformer energisation study, transformer modeling is one of the major challenges. The representation of windings, the modeling of the magnetic iron core and the ability to specify flux are the main focuses. Other than that, the interfacing network, iron saturation, losses, transformer data and the connection should also be taken into account. This paper presents a transformer model for slow-front transients caused by 50 Hz line energisation. Three single-phase 16 kVA, 11 kV/ 250 V distribution transformer models are used. This classic transformer model (include the leakage reactance and magnetising branch) are adopted from PSCAD/EMTDC master library and further modeled by combination of analytical analysis and measurements. Core saturation is modeled using an ideal current source across the specified winding; the saturation curve is constructed using curve-fitting method, generated by MATLAB Optimization. The circuit breaker is modeled using Maximum Closing Time Span (MCTS). For modeling validation, a transformer of same rating was employed as the test object. Since the PSCAD simulation and experimental measurements give similar results, it demonstrates the capability of the model to accurately represent the energisation transient of a distribution transformer.