Application of united EMD and CWD to detection of disturbance to transient power quality
Jian Li · Journal of Lanzhou University of Technology · 2012
In order to suppress the cross term interference in the Cohen-class quadratic time-frequency distribution,a method was proposed based on empirical mode decomposition(EMD) and Choi-Williams distribution.In this method,several intrinsic mode functions(IMFs) of the signals were separated from the frequency domain by using EMD.The time-frequency transformation of Cohen-class distribution was carried out after deleting the false components generated by EMD,and then the Cohen-class time-frequency distribution of original signal was reconstructed by means of linear superposition of the IMFs Cohen-class distribution results.Simulation results showed that the method could be used to suppress effectively the cross terms of Cohen-class distribution,ensure Cohen-class distribution time-frequency concentration,and extract disturbance features.