A New Hyperbolic S-Transform Based Denoising Method of Power Quality Signals
Qing Zhang · Power System Technology · 2011
To better analyze and detect power quality of power system,firstly it is necessary to reduce the noise in power quality signals.In view of the advantages of S-transform that it possesses the ability of perfectly unfolding time-frequency characteristics and high time-frequency resolution,by use of hyperbolic window function the useful signals and noise signals of power quality are transformed into phase space and the signals containing noise are decomposed into time-domain and frequency domain,then in a given time interval the freqeuency of the signals is suppressed when the given weight is within the range from 0 to 1,and then the boundary is smoothed by interpolation method.Then by means of inverse S-transform the denoised power quality signals which is demanded is attained finally.The simulation experiments of four kinds of power quality signals containing noise,i.e.,the harmonic singals,voltage sag signals,voltage interrupt signals and transient disturbance signals of voltage,are performed.The effectivenss of the proposed method is verified by comparing the results of simulation experiments with the denoising results by improved S-transform.