Application of Vector Fitting in Modelling Power System Components

Abstract

In this thesis, the application of vector fitting is presented for modelling frequencydependent behavior of power system components. The vector fitting process was applied to components such as current transformers (CTs), capacitive voltage transformers (CVTs), and different filter circuits, all of which are largely frequency-dependent with multiple resonances present in the frequency domain. To be sure that the developed models are physically realistic, passivity enforcement was applied that the models do not generate energy while being used in simulations. The significance of these models stems from their ability to compensate for distortions that occur in high-frequency ranges due to the reason of internal resonances of instrument transformers and capacitive dividers. Vector fitting is suitable for both frequency domain and time domain applications because it precisely follows the resonant behavior of components, which enables the precise approximation of rational functions. The created models can be used in simulations and in real-world measurement tasks to compensate for distortions in instrument transformers, especially under resonance and noisy measurement conditions. The results of this thesis show high accuracy, as well as proofs that vector fitting is an excellent method for constructing compact and passive models. These contributions will support future work and applications with real-world restrictions in power system analysis, measurement correction and simulation of components with resonance characteristics.

Date of Award	2025
Original language	English
Supervisor	Rastko Zivanovic (Supervisor)