US4800509A
Expired / Lapsed
US
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Detection of high resistance faults in electrical power supply network
Assignee: ABB Norden Holding AB
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Filing: 1986-12-18
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Granted: 1989-01-24
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Expires: 2006-12-18
Abstract
Abstract High resistance ground faults on a transmission line of an electrical power transmission network are detected with the aid of a device comprising a travelling wave model of the line located in measuring stations (P, Q) at either end of the line, which permits the voltage distribution along the line, seen both from P and from Q, to be obtained. A voltage ΔU Qp is formed as the difference between a votlage in station P, calculated in the travelling wave model in Q, and the corresponding voltage one period earlier. A voltage ΔU Pp is formed as the difference between a voltage calculated in the travelling wave model at P and the corresponding voltage one period earlier. The corresponding voltage differences ΔU Pq and ΔU Qq are calculated for station Q. The voltage difference ΔP is then formed as the difference between ΔU Qp and ΔU Pp , and the corresponding ΔQ is formed as the difference between ΔU Pq and ΔU Qq . Fault detection is obtained when ΔP>ε p or when ΔQ>ε q , where ⊖ p is the accepted voltage difference at P and ε q is the corresponding value at Q.
Inventors
- 👤 Gunnar Nimmersjo
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 15:25
CPC Classifications
G; G01; G01R; G01R31/00; G01R31/08; G01R31/081; G01R31/085; G01R31/11
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
382 words
A method for detecting a ground fault on an electrical power transmission line located between two stations (P, Q) included in a multi-phase electrical power transmission system, in which at two end points of the transmission line, a value for current and voltage of each phase is measured, which values are supplied to a travelling wave model of the line in the respective station, the travelling wave model being used to obtain a voltage distribution along the power transmission line as seen from each station, comprising: monitoring in each station a difference between a change in voltage on the transmission line at one station calculated with values measured at the other station before and after a suspected fault has occurred, and a change in voltage on the line at the one station calculated with values measured at the one station before and after a suspected fault has occurred, comprising the steps of: determining a value ΔU Pp as a difference between a present line voltage (U' p ), determined in station P and a corresponding line voltage (U" p ) one period earlier; determining a value ΔU Qq as a difference between a present line voltage (U' Q ), determined in station Q and a corresponding line voltage (U" Q ) one period earlier; determining a value ΔU Pq as a difference between a present line voltage (U' Pq ) in station Q, calculated in the travelling wave model in station P with values of currents and voltages measured in station P, and a corresponding voltage (U"Pq) one period earlier; determining a value ΔU Qp as a difference between a voltage (U' Qp ) in station P, calculated in the travelling wave model in station Q with values of currents and voltages measured in station Q, and a corresponding voltage (U"Qp) one period earlier; determining a value ΔP as a difference between ΔU Qp and ΔU Pp ; determining a value ΔQ as a difference between ΔU Pq and ΔU Qq ; and detecting a fault if the measured difference exceeds a preset value and comprising the step of: detecting a fault when at least one of ΔP>ε p and ΔQ>εq is determined, ε p being the accepted voltage difference in station P and ε q the corresponding value in station Q.
Claim 2
Independent Claim
382 words
A method for detecting a ground fault on an electrical power transmission line located between two stations (P, Q) included in a multi-phase electrical power transmission system, in which at two end points of the transmission line, a value for current and voltage of each phase is measured, which values are supplied to a travelling wave model of the line in the respective station, the travelling wave model being used to obtain a voltage distribution along the power transmission line as seen from each station, comprising: monitoring in each station a difference between a change in voltage on the transmission line at one station calculated with values measured at the other station before and after a suspected fault has occurred, and a change in voltage on the line at the one station calculated with values measured at the one station before and after a suspected fault has occurred, comprising the steps of: determining a value ΔU Pp as a difference between a present line voltage (U' p ), determined in station P and a corresponding line voltage (U" p ) one period earlier; determining a value ΔU Qq as a difference between a present line voltage (U' Q ), determined in station Q and a corresponding line voltage (U" Q ) one period earlier; determining a value ΔU Pq as a difference between a present line voltage (U' Pq ) in station Q, calculated in the travelling wave model in station P with values of currents and voltages measured in station P, and a corresponding voltage (U"Pq) one period earlier; determining a value ΔU Qp as a difference between a voltage (U' Qp ) in station P, calculated in the travelling wave model in station Q with values of currents and voltages measured in station Q, and a corresponding voltage (U"Qp) one period earlier; determining a value ΔP as a difference between ΔU Qp and ΔU Pp ; determining a value ΔQ as a difference between ΔU Pq and ΔU Qq ; and detecting a fault if the measured difference exceeds a preset value and comprising the step of: detecting a fault when at least one of ΔP>ε p and ΔQ>εq is determined, ε p being the accepted voltage difference in station P and ε q the corresponding value in station Q.
Claim 3
Dependent Claim
30 words
A method according to claim 1, in which ΔU Pp , ΔU Qq , ΔU Pq and ΔU Qp are formed as sums of phase voltages for the same period.
Claim 4
Dependent Claim
30 words
A method according to claim 1, in which ΔU Pp , ΔU Qq , ΔU Pq and ΔU Qp are formed as sums of principal voltages for the same period.
Claim 5
Dependent Claim
29 words
A method according to claim 1, in which in each travelling wave model used, the voltage distribution along the entire transmission line, seen from the respective station, is calculated.
Claim 6
Dependent Claim
28 words
A method according to claim 1, in which in each travelling wave model used, only the voltage in the respective station and in the remote station is calculated.
Claim 7
Dependent Claim
18 words
A method according to claim 1, in which voltages calculated from the travelling wave models are phase voltages.
Claim 8
Dependent Claim
18 words
A method according to claim 1, in which voltages calculated from the travelling wave models are principal voltages.
Claim 9
Dependent Claim
19 words
A method according to claim 1, in which voltages calculated from the travelling wave models are zero sequence voltages.
Claim 10
Dependent Claim
19 words
A method according to claim 1, in which voltages calculated from the travelling wave models are negative sequence voltages.
Claim 11
Dependent Claim
35 words
A method according to claim 1, in which the voltage differences ΔU Pp , ΔU Qq , ΔU Pq and ΔU Qp are formed as the difference between current values measured in two consecutive half-periods.
Claim 12
Dependent Claim
23 words
A method according to claim 1, in which ΔU Pp and ΔU Qq are determined by measuring the voltages in the respective stations.
Claim 13
Dependent Claim
23 words
A method according to claim 1, in which ΔU Pp and ΔU Qq are determined by calculation using the respective travelling wave model.
Claim 14
Dependent Claim
351 words
A high resistance fault detecting device for use with a power line located between two stations (P, Q), and having in each station, a travelling wave model and a plurality of summators, in one of said stations a transmitter and in the other of said stations, a receiver and comparator elements, comprising: a first summator for forming a difference voltage ΔU Pp equal to a difference between a voltage (U' P ) determined in station P during one period and a corresponding voltage (U" P ) determined one period earlier, a second summator for forming a difference voltage ΔU Qq equal to a difference between a voltage (U' Q ), determined in station Q during one period and a corresponding voltage (U" Q ) determined one period earlier, a third summator for forming a difference voltage ΔU Pq equal to a difference between a voltage (U' Pq ) in station Q, calculated in the travelling wave model in station P with values of voltages and currents measured in station P, and a corresponding voltage (U" Pq ) one period earlier, a fourth summator for forming a difference voltage ΔU' Qp equal to a difference between a voltage (U' Qp ), calculated in the travelling wave model in station Q with values of voltages and currents measured in station Q, and a corresponding voltage (U" Qp ) one period earlier, means to transfer the difference voltages ΔU Qp (ΔU Pp ) and ΔU Qq (ΔU Pq ) view the transmitter and receiver, from station Q to station P (P to Q), a fifth summator for forming a difference ΔP=ΔU Pp -ΔU Qp , a sixth summator for forming a difference ΔQ=ΔU Pq -ΔU Qq , the device delivering, via a first comparator elements, a first signal (F p ) indicating a high resistance ground fault when ΔP is greater than a voltage difference ε p accepted at station P and delivering, via a second comparator element, a second signal (F q ) indicating a high resistance ground fault when ΔQ is greater than a voltage difference ε q accepted at station Q.
Claim 15
Dependent Claim
351 words
A high resistance fault detecting device for use with a power line located between two stations (P, Q), and having in each station, a travelling wave model and a plurality of summators, in one of said stations a transmitter and in the other of said stations, a receiver and comparator elements, comprising: a first summator for forming a difference voltage ΔU Pp equal to a difference between a voltage (U' P ) determined in station P during one period and a corresponding voltage (U" P ) determined one period earlier, a second summator for forming a difference voltage ΔU Qq equal to a difference between a voltage (U' Q ), determined in station Q during one period and a corresponding voltage (U" Q ) determined one period earlier, a third summator for forming a difference voltage ΔU Pq equal to a difference between a voltage (U' Pq ) in station Q, calculated in the travelling wave model in station P with values of voltages and currents measured in station P, and a corresponding voltage (U" Pq ) one period earlier, a fourth summator for forming a difference voltage ΔU' Qp equal to a difference between a voltage (U' Qp ), calculated in the travelling wave model in station Q with values of voltages and currents measured in station Q, and a corresponding voltage (U" Qp ) one period earlier, means to transfer the difference voltages ΔU Qp (ΔU Pp ) and ΔU Qq (ΔU Pq ) view the transmitter and receiver, from station Q to station P (P to Q), a fifth summator for forming a difference ΔP=ΔU Pp -ΔU Qp , a sixth summator for forming a difference ΔQ=ΔU Pq -ΔU Qq , the device delivering, via a first comparator elements, a first signal (F p ) indicating a high resistance ground fault when ΔP is greater than a voltage difference ε p accepted at station P and delivering, via a second comparator element, a second signal (F q ) indicating a high resistance ground fault when ΔQ is greater than a voltage difference ε q accepted at station Q.
Claim 16
Dependent Claim
17 words
A device according to claim 13, in which the members thereof are suitable for analog signal processing.
Claim 17
Dependent Claim
30 words
A device according to claim 13, in which the first and second summators each determine the respective voltage U' P and U' Q by calculation using the travelling wave model.
Claim 18
Independent Claim
96 words
A method of detecting a ground fault on an electrical transmission line extending between two spaced-apart stations comprising (i) monitoring in each station a difference between (a) a change in voltage on the transmission line at one station calculated with values measured at the other station before and after a suspected fault has occurred, and (b) a change in voltage on the line at the one station calculated with values measured at the one station before and after a suspected fault has occurred, and (ii) detecting a fault if the measured difference exceeds a preset value.
Claim 19
Independent Claim
96 words
A method of detecting a ground fault on an electrical transmission line extending between two spaced-apart stations comprising (i) monitoring in each station a difference between (a) a change in voltage on the transmission line at one station calculated with values measured at the other station before and after a suspected fault has occurred, and (b) a change in voltage on the line at the one station calculated with values measured at the one station before and after a suspected fault has occurred, and (ii) detecting a fault if the measured difference exceeds a preset value.
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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) | 1992-01-24 | 1992-07-25 | 1993-01-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-01-24 | 1996-07-25 | 1997-01-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-01-24 | 2000-07-25 | 2001-01-24 | $7700.00 | Window Closed / Lapsed |