Spectral envelope estimation for transient event detection

Abstract

A Nonintursive Load Monitor (NILM) is a device that determines the operating schedule of electric loads by properly locating and identifying transient events in the spectral envelopes of the current waveform measured at the utility service entry. The spectral envelopes of the current waveform are the coefficients of its time varying Fourier series representation and as such can be estimated by low-pass filtering the current mixed with appropriate basis sinusoids. Spectral envelope estimators have been termed pre-processors. In this thesis, two pre-processors were designed. The first utilizes magic sine waves as the basis functions instead of sinusoids. The second is a digital pre-processor developed on a digital signal processor. The digital design was used in complete NILM platforms and its performance is analyzed to determine the quality of the envelopes produced. Finally, avenues for further work on the digital pre-processing unit are suggested.