A NILM algorithm with enhanced disaggregation scheme under harmonic current vectors

• Published in: Energy and buildings 2019-01, Vol.183, p.392-407
• Main Authors: Bouhouras, Aggelos S., Gkaidatzis, Paschalis A., Panagiotou, Evangelos, Poulakis, Nikolaos, Christoforidis, Georgios C.
• Format: Article
• Language: English
• Subjects: Algorithms; Amplitudes; Appliances; Disaggregation; Electric appliances; Household appliances; Load identification; Load signatures; Measuring instruments; NILM; Odd harmonic currents; Plugs; Signatures; Smart buildings
• ISSN: 0378-7788; 1872-6178
• DOI: 10.1016/j.enbuild.2018.11.013

•Load signatures are formulated based on first three odd harmonic currents.•Harmonic currents’ phase angles are measured and taken into account.•Measurements in a real residential installation have been performed.•Three alternative load signatures formations are examined.•Results indicate high NILM performance under the consideration of the phase angles. In the smart home context, one of the features that most users would desire is the knowledge of the operation of each electrical appliance without the need to install expensive smart plugs or measuring equipment at each outlet-appliance. The Non-Intrusive Load Monitoring (NILM) idea is an alternative method where only one meter is utilized. However, the accuracy and simplicity of NILM approaches are still under improvement and evolvement. In this paper we propose the development of load signatures by a limited number of harmonic current vectors. The rationale behind this is that simultaneously operating appliances may have opposite or displaced harmonic current vectors, which means that using only current amplitudes as load signatures will not result in reliable identification. Three alternative formations are examined aiming to highlight the contribution of the harmonic current phase angles to the robustness of the load signatures. The first formation considers only the current amplitude, the second takes into account the phase angles in the form of vector projection on the x-axis, and the third is based on harmonic current vectors. The respective disaggregation schemes are also proposed considering either amplitude summations or vector aggregations, in order to examine the correct appliance combination that matches the actual operating one. Measurements have been performed in a typical residential installation considering both stand-alone operation of appliances and scenarios with appliance combinations. The results indicate that disaggregation performance is significantly improved when relying on harmonic current vectors in respect to the case with only current amplitudes, which makes the methodology potentially suitable for the new smart meters that are expected to be widely installed.