Generalised harmonic domain analysis for transformer core hysteresis modelling

This work addresses a limitation in power system harmonic analysis due to the challenges of converting complex time domain models to the harmonic domain. A linear approximation, in the form of a Norton equivalent, is the simplest model necessary to describe harmonic coupling. This work expands how the Norton equivalent can be created. A general approach is developed from first principles, where a methodological starting point is established for linearising all models. Its versatility is demonstrated by converting a model of transformer magnetising current hysteresis. For this purpose, a modification is made to the classic Preisach model of hysteresis for time-periodic input and output. A new data driven method fits test results of a small transformer to the Preisach model. Results show an improved accuracy in the Norton equivalent’s frequency coupling matrices over models that only consider magnetic saturation. • Developed general methodology for creating harmonic domain Norton equivalents. • Adapted classical Preisach model of hysteresis for harmonic analysis. • Created approximate method for implementing Preisach model from symmetric test data. • Improved frequency coupling matrix for transformer open-circuit characteristics.