  Phasor measurement units (PMUs) provide a high-resolution view of the power
system at the locations where they are placed. As such, it is desirable to
place them in bulk in low voltage distribution circuits. However, the power
consumption of a PMU/micro-PMU is in the order of Watts (W) that results in
them requiring an external power supply, which in turn increases the overall
cost. This work details the hardware design of a PMU capable of measuring and
reporting voltage and current phasors for a single-phase system at an average
power consumption of only 30.8 mW -- one to two orders of magnitude lower than
existing academic and commercial PMUs. This enables the proposed PMU to run for
two weeks using an 11-Wh battery or indefinitely if paired with an inexpensive
solar panel. A test-bench developed in accordance with the 2018 IEC/IEEE
60255-118-1 PMU Standard confirms the accuracy of this PMU. Given its low power
consumption, the proposed design is expected to accelerate adoption of PMUs in
modern distribution grids.
