Analysis of a simplified digital filter for the automatic identification of transients contained in oscillographies

摘要

This work shows the development of a simplified digital filter, derived from properties of the Z-transform, with the main goal of the automatic detection and identification of transients presented in oscillographies registered by protection relays. The digital filter purposed works like a sinusoidal predictor and is implemented and compared with a transient detection technique based on the Discrete Wavelet transform. The computational routine developed is capable of detecting the beginning and the end of a transient, the instant time which the circuit breaker is closed in the case of a fault presence and the fault-type, besides the visualization of the estimated impedance along the domain of the protection units based on an offset MHO circumference. The results obtained from the application of the digital filter are consistent and promising, with the advantages of a low computational cost when compared to the Discrete Wavelet transform added to its simple implementation. Furthermore, the elaborated computational routine demonstrated practicality and adequacy for the automated using of transients detection.