Back to results
US 11,231,449 B2Granted
Frequency sensing systems and methods
AssigneeSchweitzer Engineering Laboratories, Inc.
InventorsMarcos A. Donolo, Jay Hartshorn
Life of this patent
Estimating the term…
Abstract
Systems and methods may be used to measure a frequency of a power delivery system and/or of a supply signal transmitted to a load. A system may record an input waveform, determine a frequency of the input waveform at a present time based at least in part on the input waveform and a derivative of the input waveform, and control an operation of a power delivery system based at least in part on the determined frequency.
Claims22
A system comprising:
- sensing circuitry configured to periodically sense, at a defined interval, a value of an electrical waveform on a transmission line of an electrical power transmission system;
- and
- processing circuitry configured to determine a frequency of the electrical waveform at least in part by:
- receiving a plurality of values of the electrical waveform sensed by the sensing circuitry, wherein the plurality of values comprises:
- a first value sensed by the sensing circuitry at a first time;
- and
- a plurality of previous values sensed by the sensing circuitry at times before the first time;
- determining a scaled derivative of the electrical waveform based on one or more of the plurality of values of the electrical waveform and a time to the first time;
- determining a second time corresponding to a time before the first time at which the scaled derivative of the electrical waveform has a value substantially equal to the first value of the electrical waveform at least in part by:
- determining a first time difference between the scaled derivative at a third time and the first time;
- determining a second time difference between the scaled derivative at a fourth time and the first time;
- and
- interpolating a zero crossing time as the second time using the third time and the fourth time from the first and second time differences;
- and
- determining the frequency based at least in part on a time duration between the second time and the first time;
- wherein the processing circuitry is configured to cause an operation of the electrical power transmission system to be controlled based at least in part on the frequency.
13 more elements
A method, comprising:
- receiving an input waveform comprising a plurality of sampled values each respectively sampled at time intervals equal to a defined period, wherein a first sensed value is received at a first time, and wherein the input waveform is a set of sampling values of an electrical waveform on a power line of an electrical power delivery system;
- determining a frequency of the input waveform at the first time based at least in part on a relationship between the input waveform and a derivative of the input waveform at least in part by:
- determining a second time of a scaled derivative of the input waveform at least in part by:
- determining a first time difference between the scaled derivative at a third time and the first time;
- determining a second time difference between the scaled derivative at a fourth time and the first time;
- and
- interpolating a zero crossing time as the second time based at least in part on the first and second time differences;
- and
- controlling an operation of an electric power delivery system based at least in part on the frequency of the input waveform.
6 more elements
A tangible, non-transitory, computer-readable medium comprising instructions that, when executed by a processor, cause the processor to:
- receive input waveform data sampled at a first time from sensing circuitry configured to periodically sense, at a defined interval, a value of an input waveform on a power line of an electrical power delivery system;
- determine a second time to be a time at which a scaled derivative of the input waveform data at the second time substantially equals the input waveform data at the first time at least in part by:
- determining a first time difference between the scaled derivative at a third time and the first time;
- determining a second time difference between the scaled derivative at a fourth time and the first time;
- and
- interpolating a zero crossing time as the second time using the third time and the fourth time from the first and second time differences;
- determine a time difference between the first time and the second time;
- and
- calculate a frequency of the input waveform data based at least in part on the time difference between the first time and the second time, wherein the frequency is calculated before a waveform comprising the input waveform data completes a frequency cycle.
6 more elements
Dependencies are inferred from the claim text.