Application of the harmonic balance method to study ferroresonance in voltage transformers

The determination of ferroresonant oscillations in circuits with voltage transformers is a highly nonlinear problem due to the possible core saturation. A frequency domain method is proposed, based on the harmonic balance principle, with special precautions taken for the nonlinear circuit elements. Advantages and drawbacks of this method as compared to time-domain methods are discussed for periodic oscillations. The method is then extended to allow for quasi-periodic oscillations to be studied. The damping effect of a tertiary resistor is shown for a typical configuration.