Identification of Ferroresonance on Transformer using Wavelet Transformatio

Abstract

Ferroresonance is a transient phenomenon characterized by overvoltage and waveform mismatches affected by a combination of nonlinear inductances and capacitors. Even though ferroressonance is a transient phenomenon however the impact of the ferroresonance continue for a steady state that causes excess temperature and finaly damage the impacted apparatus . Therefore, this study concern to understand and identify ferroresonance phenomena and at the end to distinguish them from other disturbances such as overvoltage and harmonics. Ferroresonance initiation is carried out on a laboratory scale using a basic circuit of ferroresonance consisting of capacitors and transformers. Two kind of transformer core topologies, namely H type and M type, was used in the experiments. Moreover other disturbances such as harmonics was also simulated in laboratory. The ferroresonance and harmonic waveform then be processed using wavelet transformations and its cumulative energy was also determined. The results shows that for H type transformer the threshold value that distinguishes ferroresonance from other disturbances is about 9.24. On the other hand for M type transformer was about 7.97. Based on these values, the type of transformer core affect the energy level of ferroresonance. Moreover wavelet transformation could identify between ferroresonance and other disturbance under study very well, however further study should be done to investigate the effectivity of wavelet to discriminate all possible mode of ferroresonance.