A Kalman-Filter Spectral Envelope Preprocessor

This paper presents a Kalman-filter approach for computing spectral envelopes of current waveforms for nonintrusive load monitoring on the electric utility. Spectral envelopes represent time-varying frequency content and phase of the current relative to the voltage. Thus, the techniques presented in this paper may be applicable to a variety of lock-in measurement and signal processing techniques. The lock-in and computational performance of the proposed method favorably compares to previous efforts. The performance is demonstrated with data from the field.