Continuous, Low Cost Cancellation of Harmonics at Power Grid Nodes

"Higher order harmonics of 60 Hz in electrical power distribution systems have been shown to significantly impact the operating life and performance characteristics of equipment vital to mission success for military facilities. To reduce unexpectedequipment failures and equipment downtime, these higher order harmonics must be prevented from entering equipment. On a facility wide basis, though, every power grid node must be protected. Because of the large number of such nodes, technologies toeliminate harmonics must be sensitive to cost considerations and must utilize a minimum of components which are susceptible to failure or faulty operation. SARA, Inc. proposes a unique and innovative method for removing higher order harmonics fromelectrical power used by mission critical equipment that is both low-cost and technologically simple. SARA's technique utilizes a single-phase core-form transformer and is based on continuously sampling the input electrical waveform, extracting the higherorder harmonic component present in the sample, amplifying and phase shifting the sample, and using the sample to drive a tertiary coil installed on the transformer core. In this manner, higher order harmonics are cancelled at the secondary coil locationby magnetic flux cancellation, and only the desired 60 Hz component is transmitted through. The proposed harmonic cancellation technique will protect critical militaryequipment from the damaging effe