Understanding ferroresonance

This paper presents a ferroresonant experience involving inductive voltage transformers (VTs) in a 400 kV substation. The origin of the phenomena, the conditions under it may become sustained and its effects on plant equipment are discussed. A very comprehensive analysis is performed using time domain simulations with ATP. Simulation results reproduced satisfactorily the ferroresonant events recorded during the field tests in the 400 kV substation. A number of mitigation options are discussed.