Study of Transient Interaction in a System with Transformer Supplied from Network through a Cable: Assessment of Interaction Frequencies and Resonance Evolvement
Keywords:Transformer windings, resonance overvoltages, winding natural oscillation frequencies, frequency response analysis, FRA, voltage measurement in transformer windings
Transformer together with its windings is a complex oscillatory system. The interaction between the transformer and an electric network during transients can cause the development of resonance phenomenon in the windings leading to overvoltages and the risk of transformer fault. This report presents the results of studies of resonance phenomena in transformer windings, caused by interaction with an electric network containing the feeder cable. The approach to a simple assessment of dominant oscillation frequency of a voltage in the system “feeder cable – transformer” and estimation of the resonant frequencies of transformer winding is considered. The report also describes the technique for measurement of winding resonance voltages. The resonance phenomenon evolvement in transformer windings is considered and the impact of decaying oscillating applied voltage on maximum ratio of resonance overvoltages is estimated.