Modelling of a voltage transformer for transients

This paper presents the modelling of a 110 kV inductive voltage transformer for transients. The inductive voltage transformer ratio typically changes a lot for frequencies up to the 50^th harmonic. To make a good model in this frequency range is the main task of this paper. A traditional lumped, linear model that includes capacitances gives satisfactory results. A new method of model capacitance estimation has been developed and is presented. The capacitance estimation is based on a real transformer measurement and recalculations. The model response was tested in EMTP/ATP and compared to the real transformer. This method can be used for simple and accurate modelling of inductive voltage transformers up to 10 kHz.