Quasi-Periodic Oscillations in a Three Phase Ferro-Resonant Circuit

When a three-phase voltage is applied to ferro-resonant circuits connected in a Y-connection, the third harmonic voltage can be obtained in the zero-phase-sequence circuit. Usually, the waveform of this voltage is almost sinusoidal and the oscillation is stable, but under some conditions the voltage changes to a state of quasi-periodic oscillations. This paper deals with the analysis of the mechanism of the quasi-periodic oscillations in a three-phase ferro-resonant circuit.