Distinctive Load Feature Extraction Based on Fryze’s Time-Domain Power Theory

The performance of a nonintrusive load monitoring (NILM) system heavily depends on the uniqueness of the preferred load signature (LS) extracted from each appliance. Some electrical characteristics, such as instantaneous current waveform (CW), instantaneous power waveform, current harmonic, and voltage-current (V-I) trajectory have been proposed as appliance features in the literature. However, in some situations, these LSs cannot effectively distinguish different loads apart. In this paper, a time-domainbased advanced power theory is used to decompose the load current into the active and nonactive orthogonal components. Then, two new LSs have been established based on the nonactive component of the load current, namely, the nonactive CW (if) and the voltage-nonactive current (V-If ) characteristics curve. Simulation and experimental tests show that both of these features can distinguish different appliances. Hence, the proposed LSs can significantly enhance the existing NILM systems.