Patent US4999565A successfully refreshed from Google Patents.
US4999565A
Expired / Lapsed
US
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Apparatus for controlling the reactive impedance of a transmission line
Assignee: Electric Power Research Institute
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Filing: 1990-01-02
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Granted: 1991-03-12
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Expires: 2010-01-02
Abstract
Abstract Apparatus for controlling the reactive impedance of a transmission line where capacitive reactance is inserted in series in the line to compensate inductive reactance includes a plurality of three or more capacitor modules connected to each other in series to form a series combination of capacitor modules. Each module is individually bypassed by fast acting thyristor bypass switches so that a central automatic control system can selectively place all of the modules in series where a maximum compensation level is achieved (meaning that the total reactive impedance is at a minimum level), or to provide a minimum change with just one capacitor module.
Inventors
- 👤 Stig L. Nilsson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 20:29
CPC Classifications
H; H02; H02J; H02J3/00; H02J3/18; H02J3/1807; Y; Y02; Y02E; Y02E40/00; Y02E40/30
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
198 words
Apparatus for controlling the reactive impedance of a transmission line where capacitive reactance is inserted in series in said line to compensate inductive reactance to a predetermined compensation level where the reactive impedance is lowered, said apparatus comprising: a plurality of three or more capacitor modules, each having a predetermined capacitive reactance, connected to each other in series to form a series combination of capacitor modules having a combined capacitive reactance represented by the arithmetic sum of said predetermined capacitive reactances, said combined capacitive reactance providing a maximum said compensation level where reactive impedance of said line is at a minimum level; said predetermined capacitive reactance of each of said capacitor modules varying in magnitude from a maximum to a minimum in substantially geometric steps for providing modulation of said compensation level from said maximum to a minimum, at least a portion of said modules including solid state bypass switches with control inputs for conductively bypassing a selected module or modules in said series combination; control means connected to the control inputs of substantially all of said modules for automatically varying said combined capacitive reactance in response to a desired change in a parameter of said transmission line.
Claim 2
Dependent Claim
198 words
Apparatus for controlling the reactive impedance of a transmission line where capacitive reactance is inserted in series in said line to compensate inductive reactance to a predetermined compensation level where the reactive impedance is lowered, said apparatus comprising: a plurality of three or more capacitor modules, each having a predetermined capacitive reactance, connected to each other in series to form a series combination of capacitor modules having a combined capacitive reactance represented by the arithmetic sum of said predetermined capacitive reactances, said combined capacitive reactance providing a maximum said compensation level where reactive impedance of said line is at a minimum level; said predetermined capacitive reactance of each of said capacitor modules varying in magnitude from a maximum to a minimum in substantially geometric steps for providing modulation of said compensation level from said maximum to a minimum, at least a portion of said modules including solid state bypass switches with control inputs for conductively bypassing a selected module or modules in said series combination; control means connected to the control inputs of substantially all of said modules for automatically varying said combined capacitive reactance in response to a desired change in a parameter of said transmission line.
Claim 3
Dependent Claim
26 words
Apparatus as in claim 1 where said parameter includes one of line current, voltage, power, frequency and said reactive impedance is adjusted to control transmitted power.
Claim 4
Dependent Claim
21 words
Apparatus as in claim 1 where said parameter is subsynchronous resonance and said reactive impedance is adjusted to eliminate said resonance.
Claim 5
Dependent Claim
15 words
Apparatus as in claim 1 where said parameter is phase shift of said transmission line.
Claim 6
Dependent Claim
18 words
Apparatus as in claim 1 where said solid state bypass switches are a pair of inversely connected thyristors.
Claim 7
Dependent Claim
51 words
Apparatus as in claim 1 where said geometric steps of said capacitive reactances of said modules are: X.sub.n =2.sup.n X.sub.1 where X is capacitive reactance, X 1 is the smallest reactance chosen for a desired minimum compensation and n is an integer varying from 0 to the total number of modules.
Claim 8
Dependent Claim
54 words
Apparatus as in claim 1 where a said series combination of capacitor modules is provided in each line of a three phase transmission line and where said control means is responsive to a fault in one line to temporarily increase impedance in such line and to reduce impedance (increase compensation) in said remaining lines.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-03-11 | 1994-09-10 | 1995-03-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-03-11 | 1998-09-10 | 1999-03-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-03-11 | 2002-09-10 | 2003-03-12 | $7700.00 | Window Closed / Lapsed |