Autonomous Calibration of Non-Contact Power Monitors

Abstract

Non-contact power monitors use electromagnetic field sensors to measure voltage and current in multiphase power lines without any ohmic contact or geometric isolation of the conductors. The complex field geometry requires these sensors to be calibrated before use. Existing work has focused on manual calibration procedures requiring a service interruption, additional loads, or other intrusive techniques. This paper introduces an autonomous calibration technique that can be used to bootstrap additional non-contact power monitors from an existing power monitor located elsewhere in the distribution network. This provides the flexibility to “zoom-in” with downstream monitors or “zoom-out” with upstream monitors and efficiently target the loads of interest. Laboratory benchmarks and installations on the U.S. Coast Guard and Naval vessels show that autonomous calibration is accurate and robust with non-contact monitors reading within 1% of commercial power meters.