Automatic Detection of Nonstationary Multiple Oscillations by an Improved Wavelet Packet Transform

Abstract

An automatic detection technique of nonstationary multiple oscillations in industrial control loops is proposed. The technique is based on an improved wavelet packet transform (WPT) which integrates Shannon Entropy, with a proposed non-Gaussianity test and quasi-intrinsic mode function index to automatically generate the wavelet packet decomposition structure. An optimal frequency resolution of the process data for oscillation detection purposes is obtained in a form of a binary tree. Comparative studies on simulated examples as well as industrial cases indicate that the proposed approach is robust to the nonstationary features of oscillations.