Defining the Unique Signatures of Loads Using the Currents’ Physical Components Theory and -Transform

A method to extract unique features from measured waveforms of nonlinear loads is presented. These features can be used for the identification of loads connected to the grid. The method is based on the currents´ physical components (CPC) electric power transport theory combined with the Z-transform (for implementation using digital signal processing (DSP). A set of admittance-based Z-transform functions that reflect the current physical components suggested by the CPC is constructed. The resulting transfer functions are shown to reflect the electric physical significance, and are used for electric load and machine identification through its electric characteristics. In this paper, the Z-transform analytic expressions are developed and extended along with their physical comprehension. Moreover, the strength of the theory over more traditional spectral analysis is explained. The method presented in this paper is demonstrated and analyzed using real-world measured waveforms (measured by power quality monitors).