Non-intrusive Zigbee power meter for load monitoring in smart buildings

Energy efficiency in smart buildings requires distributed sensing infrastructure to monitor the power consumption of appliances, machines and lighting sources. The analysis of current and voltage waveforms is fundamental for gathering diagnostic information about the power quality and for reducing power wastage. Moreover, it enables Non-intrusive Load Monitoring (NILM), which is the process of disaggregating a household's total electricity consumption into its contributing appliances, by analysing the voltage and current changes. In this paper, an innovative full Energy-neutral (i.e. battery free) and Non-intrusive Wireless Energy Meter (NIWEM) is presented to measure current, voltage and power factor. As key features, the NIWEM is completely non-invasive and it can self-sustain its operations by harvesting energy from the monitored load. It also features a standard (Zigbee) wireless interface for communication with the smart-building system. Experimental results have confirmed that complete energy sustainability can be achieved also with very low-power loads.

I. Introduction

An enormous research effort of the worldwide utility companies is oriented to monitor the energy usage for reducing power consumption, by using smart power meters for industrial, commercial and domestic scenarios. The main aim of smart power metering is to make users aware of the energy consumption in daily activities and then to promote energy saving. Standalone meters are now being replaced by distributed sensing infrastructures, which monitor the power consumption of household's appliances, using various communication strategies. Low-cost, robust and easy-to-use power sensing systems are the most suitable devices to monitor in a pervasive way the 50–60 Hz electricity in smart buildings [1].