FREQUENCY-LOCKED AND QUASI-PERIODIC (QP) OSCILLATIONS IN POWER-SYSTEMS

It is known that quasiperiodic (QP) oscillations can occur when an unl oaded power transformer at the end of a long line is energised [10]. T his occurs when the effect of the core loss of the transformer 'become s negligible' due to stiff nonlinear characteristic of the core [4]. U sually such a system is known to exhibit periodic or frequency-locked behaviour. Such a system is an equivalent form of 'two nonlinearly cou pled oscillators' and the transition from frequency-locked to quasiper iodic behaviour and vice versa depends on the strength of nonlinear co upling between the oscillators. This aspect is being examined in this paper.