Ferroresonant oscillations in a transformer terminated line due to an energised parallel line on the same right-of-way

Investigations carried out on ferroresonant oscillations in a transformer-terminated line due to an energised parallel line on the same right-of-way are reported. A nonlinear approach is used for analysis. The magnetic saturation characteristic of the individual phases of the three-phase transformer is represented and modelled by a polynomial. A topological technique is used to formulate the state space model to eliminate redundancy. Time domain simulations have been carried out using fourth-order Runge-Kutta method after corroboration with Microtran. The bifurcation diagram of the steady-state solutions is used to unearth the possible modes of ferroresonant oscillations and multiple solutions. The results reveal that with high saturation levels, chaotic ferroresonant oscillations are a distinct possibility due to the capacitive coupling between the parallel lines. Furthermore, the route to chaos is through a sequence of quasiperiodic oscillations. The sensitivities of the solutions with respect to the length of the de-energised line and the proximity between the parallel lines are analysed and discussed.