Meter any wire, anywhere by virtualizing the voltage channel

AC power meters require both voltage and current to be sampled concurrently to obtain real, reactive, and apparent power. Typically, the two measurements are taken in close physical proximity and fed into a single power metering device. In this paper, we explore the viability of decoupling the voltage and current channels, and placing them in physically disparate locations. Such decoupling could ease the installation of metering infrastructure and enable new sensing scenarios. However, decoupling the voltage and current channels raises a new question: how should they be recombined? Of the various approaches, we propose the voltage channel be virtualized: a voltage sensor measures the voltage magnitude, frequency, and phase, typically near the root of a circuit branch. The extracted phase is time-stamped relative to a global clock and disseminated wirelessly, along with the magnitude and frequency measurements, to power meters throughout the network. The power meters synthesize a suitably scaled replica of the voltage waveform locally, based on the parameters reported by the voltage sensor, and combine it with locally-measured current readings. This paper demonstrates - through empirical characterization of the line voltages, a proof-of-concept power meter implementation, and house-scale evaluation - that the design holds promise and offers substantially lower measurement errors than other distributed power metering approaches for non-resistive loads.