Electricity: electrical systems and devices – Safety and protection of systems and devices – With specific quantity comparison means
Patent
1998-03-02
2000-10-31
Jackson, Stephen W.
Electricity: electrical systems and devices
Safety and protection of systems and devices
With specific quantity comparison means
361 931, 361115, 361 62, H02H 300
Patent
active
061411965
ABSTRACT:
A method for obtaining a power system phasor includes sampling a power system signal at instants determined by a nominal power system frequency to provide a plurality of data samples; using the data samples to estimate a phasor having an elliptical trajectory; generating a deviation formula representing a frequency deviation between actual and nominal power system frequencies; and using the deviation formula to perform a coordinate transform of the estimated phasor to provide a scaled phasor having a substantially circular trajectory. If the data samples are unevenly spaced, a method in another embodiment includes minimizing squares of errors between the unevenly spaced data samples and an approximating sinusoidal function of the data samples. Power system phasors can be used to detect turn faults by providing scaled current and voltage phasors; extracting fundamental voltage and current phasors; and applying a symmetrical component transform to the fundamental voltage and current phasors to obtain symmetrical component voltage and current phasors for use in determining the existence of a turn fault. Variance calculations and/or trigonometric function fits can be used to increase sensitivity of fault detection.
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Adamiak Mark Gerald
Esser Albert Andreas Maria
Hoeweler David Jeremiah
Kliman Gerald Burt
Koegl Rudolph Alfred Albert
Agosti Ann M.
Breedlove Jill M.
General Electric Company
Jackson Stephen W.
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