Simplified modelling of an air-core reactor for lightning impulse transient studies

This paper presents a methodology that can be used to model the electromagnetic behaviour of large disk type air-core reactors when excited by fast transient voltages having a frequency content ranging from 10 kHz to 500 kHz. The subject of transient voltages in complex winding structures has been extensively studied for more than a century resulting in increasingly complex model synthesis and parameter acquisition methods to increase accuracy. The novelty in this work however, lies in the study of a particular composition of simple well-known methodologies and an analysis of its suitability this context. A lumped parameter white-box model is generated using the design details of the reactor. The model parameters are calculated analytically and frequency dependency is mostly omitted for the sake of simplification in the methodology. The parameters are verified by measurements and finite element method simulations. The modelling methodology is applied to an actual case study and the simulation results are compared to the measured results. The model response varies in its performance. The results are good when evaluating the voltages to ground in the frequency domain. However with evaluation in the time domain it becomes clear than the methodology still needs improvement. Restrictions and limitations of the simplified model are discussed.