US3906335A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Frequency regulating device for A.C. systems interconnected through D.C. systems
Assignee: Hitachi Ltd
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Filing: 1974-03-11
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Granted: 1975-09-16
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Expires: 1994-03-11
Abstract
Abstract In a system interconnection composed of two a.c. systems, two converters connected with the respective a.c. systems and a d.c. power transmission system, one of the converters or rectifier is subject to constant current control and the other or inverter is subject to constant margin angle control. In the control system, the difference between the frequencies of the a.c. systems to which the respective converters are connected is utilized for modifying the set point of control. The greater the frequency difference, the rate of modification of the set point is increased so as to minimize the frequency difference between the a.c. systems remaining after control.
Inventors
- 👤 Atsumi Watanabe
- 👤 Hisao Amano
- 👤 Akira Isono
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 03:53
CPC Classifications
H; H02; H02J; H02J3/00; H02J3/36; Y; Y02; Y02E; Y02E60/00; Y02E60/60
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
226 words
A control system for a system interconnection consisting of two a.c. systems interconnected by a d.c. power transmission system, comprising a rectifier and an inverter in said d.c. power transmission system, means including at least constant current control means associated with said rectifier for controlling the current in said d.c. power transmission system to a constant value, and means for modifying the set point of said constant current control means depending on the frequency difference between the two a.c. systems so that the set point of said constant current control means can be greatly modified with the increase in the frequency difference, said means for modifying including first means for detecting the frequencies of the respective a.c. systems to convert the same into corresponding voltage signals, second means for seeking the difference between the frequencies of the two a.c. systems on the basis of the voltage signal outputs of said first means, third means for amplifying the output of said third means representing the frequency difference, and fourth means connected to said third means for delivering a signal for modifying the current setting of the d.c. power transmission system, said third means having a non-linear characteristic so that the rate of increase or decrease in the power being tramsmitted through the d.c. power transmission system can be greatly increased with the increase in the frequency difference.
Claim 2
Dependent Claim
226 words
A control system for a system interconnection consisting of two a.c. systems interconnected by a d.c. power transmission system, comprising a rectifier and an inverter in said d.c. power transmission system, means including at least constant current control means associated with said rectifier for controlling the current in said d.c. power transmission system to a constant value, and means for modifying the set point of said constant current control means depending on the frequency difference between the two a.c. systems so that the set point of said constant current control means can be greatly modified with the increase in the frequency difference, said means for modifying including first means for detecting the frequencies of the respective a.c. systems to convert the same into corresponding voltage signals, second means for seeking the difference between the frequencies of the two a.c. systems on the basis of the voltage signal outputs of said first means, third means for amplifying the output of said third means representing the frequency difference, and fourth means connected to said third means for delivering a signal for modifying the current setting of the d.c. power transmission system, said third means having a non-linear characteristic so that the rate of increase or decrease in the power being tramsmitted through the d.c. power transmission system can be greatly increased with the increase in the frequency difference.
Claim 3
Dependent Claim
50 words
A control system as claimed in claim 1, comprising a plurality of comparators for comparing the frequency difference with a plurality of different settings, and an adder for seeking the sum of the frequency difference and the outputs of said comparators, the output of said adder providing said modifying signal.
Claim 4
Dependent Claim
27 words
A control system as claimed in claim 2, wherein said comparators are set to have a hysteresis characteristic in providing the outputs relative to the frequency difference.
Claim 5
Dependent Claim
23 words
A control system as claimed in claim 3, wherein said hysteresis characteristic is obtained by provision of timer means in said control system.
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) | 1978-09-15 | 1979-03-17 | 1979-09-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-15 | 1983-03-17 | 1983-09-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-15 | 1987-03-17 | 1987-09-16 | $7700.00 | Window Closed / Lapsed |