Patent US4743827A successfully refreshed from Google Patents.
US4743827A
Expired / Lapsed
US
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Variable speed pumping-up electrical power system
Assignee: Hitachi Ltd
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Filing: 1987-04-29
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Granted: 1988-05-10
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Expires: 2007-04-29
Abstract
Abstract Disclosed in a variable speed pumping-up electrical power system comprising a variable speed generator/motor, a frequency converter connected between the generator/motor and an a.c. power system, a controller controlling an effective power input to the generator/motor by controlling the frequency converter on the basis of the difference between an actual effective power input from the a.c. power system and an externally-applied effective power command, and a correction circuit correcting the effective power command on the basis of the difference between the frequency of the a.c. power system and a frequency setting.
Inventors
- 👤 Junichi Shiozaki
- 👤 Takao Kuwabara
- 👤 Akira Bando
- 👤 Kenichi Ono
- 👤 Akihiro Sakayori
- 👤 Ichiro Hitomi
- 👤 Masahiro Minato
- 👤 Shigeaki Hayashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 18:07
CPC Classifications
H; H02; H02J; H02J15/00; H02J15/10; H02P; H02P9/00; H02P9/42; Y; Y02; Y02E; Y02E10/00; Y02E10/20; Y02E60/00; Y02E60/16
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
158 words
A variable speed pumping-up electrical power system comprising: a variable speed electrical machine; a frequency converter connected between said variable speed electrical machine and an a.c. power system; a pump/turbine driven by said variable speed electrical machine; a speed detector detecting the rotation speed of said pump/turbine; a power detector detecting effective power supplied to said variable speed electrical machine from said a.c. power system; a frequency converter controller controlling said frequency converter so as to eliminate any error between the value of effective power detected by said power detector and the value of effective power commanded by an externally-applied effective power command signal, a frequency detector detecting the frequency of said a.c. power system, a frequency controller comparing the frequency detected by said frequency detector with a frequency setting to generate a correction signal for correcting said effective power command signal, and means for correcting the value of the externally commanded effective power by said correction signal.
Claim 2
Dependent Claim
158 words
A variable speed pumping-up electrical power system comprising: a variable speed electrical machine; a frequency converter connected between said variable speed electrical machine and an a.c. power system; a pump/turbine driven by said variable speed electrical machine; a speed detector detecting the rotation speed of said pump/turbine; a power detector detecting effective power supplied to said variable speed electrical machine from said a.c. power system; a frequency converter controller controlling said frequency converter so as to eliminate any error between the value of effective power detected by said power detector and the value of effective power commanded by an externally-applied effective power command signal, a frequency detector detecting the frequency of said a.c. power system, a frequency controller comparing the frequency detected by said frequency detector with a frequency setting to generate a correction signal for correcting said effective power command signal, and means for correcting the value of the externally commanded effective power by said correction signal.
Claim 3
Dependent Claim
55 words
A variable speed pumping-up electrical power system according to claim 1, further comprising means for correcting the value of the externally commanded effective power on the basis of a deviation of the rotation speed of said pump/turbine detected by said speed detector from an upper limit and a lower limit of a predetermined speed range.
Claim 4
Dependent Claim
50 words
A variable speed pumping-up electrical power system according to claim 1, further comprising means for generating a control signal controlling the opening of guide vanes of said pump/turbine as a function of a pumping-up head of said pump/turbine and the rotation speed of said pump/turbine detected by said speed detector.
Claim 5
Dependent Claim
55 words
A variable speed pumping-up electrical power system according to claim 3, further comprising means for correcting the value of the externally commanded effective power on the basis of a deviation of the rotation speed of said pump/turbine detected by said speed detector from an upper limit and a lower limit of a predetermined speed range.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-05-10 | 1991-11-09 | 1992-05-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-05-10 | 1995-11-09 | 1996-05-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-05-10 | 1999-11-09 | 2000-05-10 | $7700.00 | Window Closed / Lapsed |