Identifying Variable-Power Appliances in Non-intrusive Load Monitoring Systems

Abstract

Appliance load monitoring is critical to household energy management. In recent years, non-intrusive load monitoring (NILM) is considered as an attractive method for appliance load monitoring, as it aims to separate household energy consumption data collected from a single point of measurement into appliance-level consumption data. While the NILM idea seems feasible, practical NILM implementation suffers from the problem of accurately tracking the appliance usage. One major issue for the NILM accuracy problem is that not every appliance is with a distinguishable and deterministic signature. Several appliances are with variable power consumption during operation. The presence of the variable power appliances in a NILM system complicates disaggregation in the NILM system, as the NILM system relies on the identification of steady states of individual appliances. In this paper, we address the problem of identifying 220 volts variable-power appliances in NILM systems. We introduce a technique to remove the distortion caused by 220 volts variable-power appliances in NILM systems. The core idea is that the power consumption of the 220 volts appliances is provided by two current supplies in the common single-phase three wires power distribution. By detecting the synchronized status of the two current supplies, the usage of the 220 volts appliance can be identified. This paper summarizes our observation, the idea, and the proposed algorithms. Experiments are made to demonstrate the effectiveness of the proposed techniques.