US4352137A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Methods and apparatus for fault detection
Assignee: The General Electric Company PLC
•
Filing: 1981-02-25
•
Granted: 1982-09-28
•
Expires: 2001-02-25
Abstract
Abstract This invention relates to methods and apparatus for detecting the occurrence of a fault on a conductor or transmission line and for protecting the conductor or line in accordance with the determination of fault. The instantaneous value of the voltage (V) and current (i), or the modal components of that voltage and current in the case of a polyphase line, are formed into two functions S 1R and S 2R , which are of the general form V-iR and V+iR respectively where R is a replica of the surge impedance of the line. Superimposed components of these functions are derived by continuously subtracting the steady-state value of each function from its instantaneous value. The sequence in which the functions obtain a value outside a predetermined band of values is monitored to provide an indication of the existence and direction of a fault with respect to the measuring point. Trip and block signals are generated for operating circuit breakers.
Inventors
- 👤 Allan T. Johns
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 08:06
CPC Classifications
H; H02; H02H; H02H7/00; H02H7/26; H02H7/265; G; G01; G01R; G01R27/00; G01R27/02; G01R27/16; G01R27/18; G01R31/00; G01R31/50; G01R31/58; H02H7/261; H02H7/262
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
159 words
A method of determining the direction of a fault on an electrical conductor from a monitoring position along the length of the conductor comprising: forming first and second signals S 1R and S 2R of the form: S.sub.1R =K.sub.1 V.sub.fr (t)-K.sub.2 Ri.sub.R (t) S.sub.2R =K.sub.3 V.sub.fr (t)+K.sub.4 Ri.sub.R (t) where V fr (t) is a signal proportional to the difference between the steady-state voltage and the instantaneous voltage on the conductor at the monitoring position; Ri R (t) is a signal proportional to the product of the difference between the steady-state current and the instantaneous current on the conductor at the monitoring position and a constant (R) which is related to the surge impedance of the conductor; and each of K 1 ,K 2 ,K 3 and K 4 is a positive or negative constant; and determining the sequence in which the signals S 1R and S 2R vary from selected values, and thereby the direction of the fault.
Claim 2
Independent Claim
159 words
A method of determining the direction of a fault on an electrical conductor from a monitoring position along the length of the conductor comprising: forming first and second signals S 1R and S 2R of the form: S.sub.1R =K.sub.1 V.sub.fr (t)-K.sub.2 Ri.sub.R (t) S.sub.2R =K.sub.3 V.sub.fr (t)+K.sub.4 Ri.sub.R (t) where V fr (t) is a signal proportional to the difference between the steady-state voltage and the instantaneous voltage on the conductor at the monitoring position; Ri R (t) is a signal proportional to the product of the difference between the steady-state current and the instantaneous current on the conductor at the monitoring position and a constant (R) which is related to the surge impedance of the conductor; and each of K 1 ,K 2 ,K 3 and K 4 is a positive or negative constant; and determining the sequence in which the signals S 1R and S 2R vary from selected values, and thereby the direction of the fault.
Claim 3
Dependent Claim
32 words
A method according to claim 1 wherein the direction of the fault is determined by determining which of the signals S 1R and S 2R first varies from the relevant selected value.
Claim 4
Dependent Claim
29 words
A method according to claim 1 wherein the direction of the fault is determined by determining the sequence in which the signals S 1R and S 2R become finite.
Claim 5
Dependent Claim
26 words
A method according to claim 3 wherein a signal S 1R or S 2R is taken to be finite when it exceeds a predetermined setting level.
Claim 6
Dependent Claim
25 words
A method according to claim 1 wherein the signals S 1R and S 2R are formed from modal components of the conductor voltage and current.
Claim 7
Dependent Claim
41 words
A method of determining the direction of a fault in a polyphase alternating current electric power supply system wherein the direction of a fault on each phase conductor of the system is individually determined by a method according to claim 5.
Claim 8
Dependent Claim
157 words
Apparatus for determining the direction of a fault on an electrical conductor from a monitoring position along the length of the conductor comprising: means for forming first and second signals S 1R and S 2R of the form: S.sub.1R =K.sub.1 V.sub.fr (t)-K.sub.2 Ri.sub.R (t) S.sub.2R =K.sub.3 V.sub.fr (t)+K.sub.4 Ri.sub.R (t) where V fr (t) is a signal proportional to the difference between the steady-state voltage and the instantaneous voltage on the conductor at the monitoring position; Ri R (t) is a signal proportional to the product of the difference between the steady-state current and the instantaneous current on the conductor at the monitoring position and a constant (R) which is related to the surge impedance of the conductor; and each of K 1 ,K 2 ,K 3 and K 4 is a positive or negative constant; and sequence detector means for determining the sequence in which the signals S 1R and S 2R vary from selected values.
Claim 9
Dependent Claim
157 words
Apparatus for determining the direction of a fault on an electrical conductor from a monitoring position along the length of the conductor comprising: means for forming first and second signals S 1R and S 2R of the form: S.sub.1R =K.sub.1 V.sub.fr (t)-K.sub.2 Ri.sub.R (t) S.sub.2R =K.sub.3 V.sub.fr (t)+K.sub.4 Ri.sub.R (t) where V fr (t) is a signal proportional to the difference between the steady-state voltage and the instantaneous voltage on the conductor at the monitoring position; Ri R (t) is a signal proportional to the product of the difference between the steady-state current and the instantaneous current on the conductor at the monitoring position and a constant (R) which is related to the surge impedance of the conductor; and each of K 1 ,K 2 ,K 3 and K 4 is a positive or negative constant; and sequence detector means for determining the sequence in which the signals S 1R and S 2R vary from selected values.
Claim 10
Dependent Claim
26 words
Apparatus according to claim 7 wherein said detector means determines which of the signals S 1R and S 2R first varies from the relevant selected value.
Claim 11
Dependent Claim
23 words
Apparatus according to claim 7 wherein said detector means determines the sequence in which the signals S 1R and S 2R become finite.
Claim 12
Dependent Claim
25 words
Apparatus according to claim 9 wherein a signal S 1R or S 2R is taken to be finite when it exceeds a predetermined setting level.
Claim 13
Dependent Claim
71 words
Apparatus according to claim 7 wherein the means for forming the signals S 1R and S 2R comprises: means for sensing the voltage and current on the conductor; means for forming modal components of the conductor voltage and current; and means for utilizing said voltage and current modal components and a replica impedance representative of the surge impedance of the conductor to form said signals S 1R and S 2R .
Claim 14
Dependent Claim
37 words
Apparatus for determining the direction of a fault in a polyphase electric power transmission line comprising an individual apparatus according to claim 11 for determining the direction of a fault on each phase conductor of the system.
Claim 15
Dependent Claim
117 words
Apparatus according to claim 7 for determining the direction of a fault in an alternating current electric power supply system wherein said means for forming said signals S 1R and S 2R incorporates means for producing an output signal representative of the difference between the steady state and instantaneous values of an input signal comprising: subtracting means having first and second inputs; means for applying said input signal to one input of the subtracting means; a delay means; and means for applying said input signal to the second input of the subtracting means via said delay means, the delay means providing a delay which is an integral multiple of half the period of the alternating current waveform.
Claim 16
Dependent Claim
13 words
Apparatus according to claim 13 wherein said delay means comprises a charge-coupled device.
Claim 17
Dependent Claim
78 words
A power line protection system comprising: an apparatus for determining the direction of a fault according to claim 7 at each end of a section of power line to be protected; switching apparatus for protecting said line section in the event of a fault; and decision means responsive to the outputs of both said fault direction determining apparatuses to determine whether a fault has occurred within or without said line section, and to activate said switching apparatus accordingly.
Claim 18
Dependent Claim
33 words
A system according to claim 15 wherein said decision means activates said switching apparatus only when both said fault determining direction apparatuses detect a fault in a direction looking into said line section.
References Cited (Backward Citations)
US3524075A
Cited
US3931502A
Cited
US3983456A
Cited
US4128805A
Cited
US4251766A
Cited
US4234901A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-09-27 | 1986-03-29 | 1986-09-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-09-27 | 1990-03-29 | 1990-09-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-09-27 | 1994-03-29 | 1994-09-28 | $7700.00 | Window Closed / Lapsed |