Patent US3758763A successfully refreshed from Google Patents.
US3758763A
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Method of digitally processing sinusoidal ac signals
Assignee: Hitachi Ltd
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Filing: 1971-11-05
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Granted: 1973-09-11
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Expires: 1991-11-05
Abstract
Abstract A sinusoidal ac signal is subjected to periodic sampling having a period Delta t. There is made a product of one sampled value of the signal taken at a certain sampling point and another sampled value at the next sampling point apart, by an interval of time equal to the period Delta t, from the previous sampling point. If the product is of negative value, a zero point of the signal must lie between the two sampling points. The zero point can equivalently be obtained by drawing a straight line passing the two sampled values. On the basis of the zero points of sinusoidal ac signals obtained in such a manner as above, the frequencies, phase differences, powers and the impedances of the associated transmission lines are obtained by means of a digital computer.
Inventors
- 👤 H Nohara
- 👤 J Makino
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 10:30
CPC Classifications
G; G01; G01R; G01R21/00; G01R21/133; H; H02; H02H; H02H3/00; H02H3/08; H02H3/26; H02H3/265; H02H3/40; H02H3/42; H02H3/46; H03; H03K; H03K5/00; H03K5/153
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
146 words
A method of digitally processing sinusoidal ac quantities for the operation of a power system, said method comprising the steps of: sampling at least one ac input quantity at a constant period and holding the sampled values; converting each of the sampled and held values into a digital quantity; storing said digital quantity; producing, at every sampling, the product of a digital quantity corresponding to the instantly sampled value and the stored digital quantity corresponding to the value sampled at the preceding sampling; judging whether said product is one of a negative value, a positive value and a zero value; and determining a zero point of the sinusoidal ac quantity on the basis of said two digital quantities from which said product has been obtained and the sampling period, if the result of the above judgement is one of a negative value and a zero value.
Claim 2
Independent Claim
146 words
A method of digitally processing sinusoidal ac quantities for the operation of a power system, said method comprising the steps of: sampling at least one ac input quantity at a constant period and holding the sampled values; converting each of the sampled and held values into a digital quantity; storing said digital quantity; producing, at every sampling, the product of a digital quantity corresponding to the instantly sampled value and the stored digital quantity corresponding to the value sampled at the preceding sampling; judging whether said product is one of a negative value, a positive value and a zero value; and determining a zero point of the sinusoidal ac quantity on the basis of said two digital quantities from which said product has been obtained and the sampling period, if the result of the above judgement is one of a negative value and a zero value.
Claim 3
Dependent Claim
58 words
A method according to claim 1, which further includes additional steps of: determining the sine of an angle equivalent to the time of the zero point relative to the sampling point; and deriving the peak value of the sinusoidal ac quantity from the value of said sine and the digital value of the quantity at the sampling point.
Claim 4
Dependent Claim
48 words
A method according to claim 1, which further includes additional steps of: counting the number of the sampling periods contained between two adjacent zero points of the ac quantity; and determining the frequency of said ac quantity from said number of sampling periods and said two sampling points.
Claim 5
Dependent Claim
67 words
A method according to claim 1, which further includes additional steps of: judging the one of lag and lead in phase between two sinusoidal ac quantities from the respective digital values of said two quantities taken at two sampling points; and determining the phase difference between said two ac quantities from the result of the above judgment and the respective zero points of said two ac quantities.
Claim 6
Dependent Claim
160 words
A method according to claim 4, wherein two sinusoidal ac quantities are the voltage and the current in a power transmission line and said method further includes additional steps of: determining the sine value of one of said two ac quantities on the basis of the zero point, and one of lag and lead relation in phase and the phase difference between said two ac quantities, deriving the peak value of said one ac quantitY from said sine value and the digital value of said one ac quantity, determining the sine value of the other of said two ac quantities on the basis of the zero point, the one of lag and lead relation in phase and the phase difference between said two ac quantities, deriving the peak value of said other ac quantity from the sine value thereof and the digital value of said ac quantity, and determining the ratio of the respective peak values of said ac quantities.
Claim 7
Dependent Claim
180 words
A method according to claim 4, wherein two sinusoidal ac quantities are the voltage and the current in a power transmission line and said method further includes additional steps of: determining the sine value of one of said two ac quantities on the basis of the zero point, the one of lag and lead relation in phase and the phase difference between two ac quantities, deriving the peak value of said one ac quantity from said sine value and the digital value of said one ac quantity, determining the sine value of the other of said two ac quantities on the basis of the zero point, the one of lag and lead relation in phase and the phase difference between said two ac quantities, deriving the peak value of said other ac quantity from the sine value thereof and the digital value of said ac quantity, determining the cosine value of an angle corresponding to the phase difference between said two ac quantities, and deriving the product of said cosine value and the peak values of the respective ac quantities.
Claim 8
Dependent Claim
18 words
A method according to claim 1, wherein the step of sampling includes sampling a plurality of ac quantities.
Claim 9
Dependent Claim
235 words
Apparatus for processing sinusoidal ac signals comprising: first means for generating a timing signal for the sampling of at least one ac signal; second means for sampling each said ac signal in synchronism with said timing signal and for holding the sampled values of each said ac signal for a predetermined time; third means for generating at least first, second, third and fourth control signals in accordance with said timing signal; fourth means responsive to the first control signal for selectively passing the outputs of said second means; fifth means responsive to the second control signal for converting the output of said fourth means into a corresponding digital quantity; sixth means responsive to the third control signal for storing the output of said fifth means; seventh means responsive to the fourth control signal for receiving the output of said sixth means; said seventh means including means for providing output of the product A(tn). A(tn 1), A(tn) and A(tn 1) being the sampled values of each said ac signal A(t) at a certain sampling point tn and another sampling point tn 1earlier by one sampling period than tn, respectively, sign means for providing a first output when said product is one of a negative value and a zero value, and means responsive to the first output of said sign means for determining the zero point of each said ac signal in accordance with the sampled values.
Claim 10
Dependent Claim
235 words
Apparatus for processing sinusoidal ac signals comprising: first means for generating a timing signal for the sampling of at least one ac signal; second means for sampling each said ac signal in synchronism with said timing signal and for holding the sampled values of each said ac signal for a predetermined time; third means for generating at least first, second, third and fourth control signals in accordance with said timing signal; fourth means responsive to the first control signal for selectively passing the outputs of said second means; fifth means responsive to the second control signal for converting the output of said fourth means into a corresponding digital quantity; sixth means responsive to the third control signal for storing the output of said fifth means; seventh means responsive to the fourth control signal for receiving the output of said sixth means; said seventh means including means for providing output of the product A(tn). A(tn 1), A(tn) and A(tn 1) being the sampled values of each said ac signal A(t) at a certain sampling point tn and another sampling point tn 1earlier by one sampling period than tn, respectively, sign means for providing a first output when said product is one of a negative value and a zero value, and means responsive to the first output of said sign means for determining the zero point of each said ac signal in accordance with the sampled values.
Claim 11
Dependent Claim
55 words
Apparatus according to claim 8, wherein said sign means provides a second output when said product is a positive value, and counter means responsive to the second output of said sign means for counting the number of sampling pulses occurring during the interval when the second output of said sign means continues to be positive.
Claim 12
Dependent Claim
52 words
Apparatus according to claim 8, wherein two ac signals are sampled, and said seventh means includes means for calculating the phase difference between the two ac signals in accordance with the zero point of one of the two ac signals and the zero point of the other of said two ac signals.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-09-10 | 1977-03-12 | 1977-09-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-09-10 | 1981-03-12 | 1981-09-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-09-10 | 1985-03-12 | 1985-09-11 | $7700.00 | Window Closed / Lapsed |