US4661769A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Measurement of magnitude and phase angle of voltage and current phasors and frequency deviation in power systems
Assignee: University of North Carolina at Chapel Hill
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Filing: 1985-01-23
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Granted: 1987-04-28
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Expires: 2005-01-23
Abstract
Abstract Methods for determining magnitude, phase angle and frequency deviation in the sinusoid waveform output of electrical power generation equipment are disclosed. The first method uses a two-state linear Kalman filter to calculate the magnitude and phase angle from which the frequency deviation is calculated using the linear relationship between frequency deviation and the average rate of change of phase angle. In a second method, a three-state extended Kaman filter is employed. The frequency deviation is considered a third state variable and is recursively computed on-line.
Inventors
- 👤 Adly A. Girgis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 08:55
CPC Classifications
G; G01; G01R; G01R25/00; G01R23/00; G01R23/02; G01R23/12
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
122 words
A method of determining frequency deviation in the sinusoid wavefrom output of electrical power generation apparatus characterized by the fact that the method is accurate in the presence of noise and that it minimizes error introudced by such noise comprisng the steps of: successively sampling the voltage output of the sinusoid waveform of an electrical power generation apparatus; recursively electronically calculating in response to said successive sampling a voltage waveform sinusoid estimate by optimal estimation using state variables, said optimal estimation including electronically calculating the magnitude and phase angle of said sample from said state variables; and electronically calculating the frequency deviation of said voltage waveform by linearly relating the frequency deviation to the average rate of change of said phase angle.
Claim 2
Independent Claim
122 words
A method of determining frequency deviation in the sinusoid wavefrom output of electrical power generation apparatus characterized by the fact that the method is accurate in the presence of noise and that it minimizes error introudced by such noise comprisng the steps of: successively sampling the voltage output of the sinusoid waveform of an electrical power generation apparatus; recursively electronically calculating in response to said successive sampling a voltage waveform sinusoid estimate by optimal estimation using state variables, said optimal estimation including electronically calculating the magnitude and phase angle of said sample from said state variables; and electronically calculating the frequency deviation of said voltage waveform by linearly relating the frequency deviation to the average rate of change of said phase angle.
Claim 3
Dependent Claim
19 words
The method of determining frequency deviation claimed in claim 1 wherein said optimal estimation procedure uses two state variables.
Claim 4
Dependent Claim
20 words
The method of determining frequency deviation claimed in claim 1 wherein said successive sampling uses successive pairs of successive samples.
Claim 5
Dependent Claim
28 words
The method of determining frequency deviation claimed in claim 2 wherein the two state variables of said frequency deviation estimation procedure correspond to the amplitudes in-phase and quadrature-phase.
Claim 6
Dependent Claim
21 words
The method of determining frequency deviation claimed in claim 1 wherein said estimation procedure is in accordance with discrete Kalman Filtering.
Claim 7
Independent Claim
98 words
A method of determining frequency deviation in the sinusoid waveform output of electrical power generation apparatus characterized by the fact that the method is accurate in the presence of noise and that it minimizes error introduced by such noise comprising the steps of: successively sampling the voltage output sinusoid waveform of an electrical power generation apparatus; recursively electronically calculating in response to said successive sampling, a voltage waveform sinusoid estimate by means of an estimation procedure having three state variables and wherein one of said three state variables corresponds to the frequency deviation of said output sinusoid waveform.
Claim 8
Independent Claim
98 words
A method of determining frequency deviation in the sinusoid waveform output of electrical power generation apparatus characterized by the fact that the method is accurate in the presence of noise and that it minimizes error introduced by such noise comprising the steps of: successively sampling the voltage output sinusoid waveform of an electrical power generation apparatus; recursively electronically calculating in response to said successive sampling, a voltage waveform sinusoid estimate by means of an estimation procedure having three state variables and wherein one of said three state variables corresponds to the frequency deviation of said output sinusoid waveform.
Claim 9
Dependent Claim
20 words
The method of determining frequency deviation claimed in claim 6 wherein said successive sampling uses successive pairs of successive samples.
Claim 10
Dependent Claim
31 words
The method of determining frequency deviation claimed in claim 6 wherein the three state variables of said frequency deviation estimation procedure correspond to the amplitudes in-phase and quadrature-phase and frequency deviation.
Claim 11
Dependent Claim
21 words
The method of determining frequency deviation claimed in claim 6 wherein said estimation procedure is in accordance with discrete Kalman Filtering.
Claim 12
Dependent Claim
21 words
The method of determining frequency deviation claimed in claim 6 wherein said estimation procedure is in accordance with extended Kalman Filtering.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1990-04-27 | 1990-10-27 | 1991-04-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-04-27 | 1994-10-27 | 1995-04-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-04-27 | 1998-10-27 | 1999-04-28 | $7700.00 | Window Closed / Lapsed |