Variational mode decomposition method (VMD) applied to Decay Ratio (DR) calculation for instabilities identification in BWR

Abstract

Decay Ratio (DR) is the stability indicator most used in Boiling Water Reactors. Its calculation can be performed by several methods which can lead to errors due to the fact that instability time series are not stationary. In the last years, several authors have proposed to use decomposition methods such Empirical Mode Decomposition (EMD) or Ensemble Empirical Mode Decomposition (EEMD) to obtain mono-frequency modes from the original signal. These techniques, although useful, produce mode mixing and they are not completely valid for an on-line implementation. Variational Mode Decomposition (VMD) is a recently developed algorithm which solves the mode mixing problem. In this work it has been used to improve the estimation of DR: Comparisons with traditional methods are also included.