  This paper describes the application of the adaptive whitening filter and the
wavelet transform used to detect the abrupt changes in the signals recorded
during disturbances in the electrical power network in South Africa. Main focus
has been to estimate exactly the time-instants of the changes in the signal
model parameters during the pre-fault condition and following events like
initiation of fault, circuit-breaker opening, auto-reclosure of the
circuit-breakers. The key idea is to decompose the fault signals, de-noised
using the adaptive whitening filter, into effective detailed and smoothed
version using the multiresolution signal decomposition technique based on
discrete wavelet transform. Then we apply the threshold method on the
decomposed signals to estimate the change time-instants, segmenting the fault
signals into the event-specific sections for further signal processing and
analysis. This paper presents application on the recorded signals in the power
transmission network of South Africa.
