Ferroresonance in power systems: fundamental solutions

Ferroresonance can occur in power transformers or reactors fed through capacitive coupling from neighbouring phases or lines. Ritz´s method of harmonic balance is used to formulate an analytical solution to the problem of fundamental frequency ferroresonance. A two-term polynomial of order 11 is used to accurately represent the magnetisation characteristic of a typical high-voltage power transformer in the ferroresonance region. The derived closed-form solutions permit construction of a map defining the boundaries between safe and ferroresonant regions as a function of the system parameters. The transformer losses are included in the analysis and are shown to be an important factor in the demarcation of the ferroresonance regions