A Non-Intrusive Load Monitoring System Based on A Cascaded Method

Non-intrusive load monitoring (NILM) refers to a method of detecting the current energy consumptions of a house or a building using a single set of sensors at the utility service entry (USE). The voltage of USE in Taiwan can vary within +/- 5%. NILM, which uses active (P) and reactive powers (Q) as the load signatures may suffer from very low detection rates. In this paper, we proposed a new NILM method based on cascaded strategy. The proposed algorithm consists of three stages. In the first stage, the conventional PQ method will be employed. In the second stage, a linearized admittance method will be used to update the fundamental components of the current signals in the database due the voltage variations at USE. Finally, in the third stage, the updated current spectra from the second stage will be used for identifying the loads passed down from the first stage. It is shown via experiments that the proposed method yield better detection rate than the conventional PQ method.