US 4,731,689 AGranted

Directional detection in connection with faults in a power supply network

AssigneeAsea AB

InventorsGunnar Nimmersjo, Murari M. Saha

Life of this patent

Estimating the term…

Loading patent…

Abstract

A method and a device for directional detection of a fault on a power transmission line extending between two stations (P, Q). In one of the stations (P) there is a travelling wave model which, by means of currents and voltages measured in the station, calculates the voltage distirbution along the line. The direction to a fault is determined by monitoring changes in calculated voltages in the two stations. If a fault occurs between the stations, the voltage change occurring in a station (Q) between the voltage existing prior to a fault and after a fault can be estimated as .vertline..DELTA.Uq.vertline., and the corresponding voltage change occurring in the other station (P) can be estimated as .vertline..DELTA.Up.vertline., whereby according to the invention the difference .vertline..DELTA.Uq.vertline.-.vertline..DELTA.Up.vertline.>0 signifies a fault on the line side of the station (P), i.e. a fault lying ahead of the measuring point. A fault lying behind station P is evidenced when .vertline..DELTA.Uq.vertline.-.vertline..DELTA.Up.vertline.<0.

Claims5

Dependent claims

A method for directional detection of a fault on a power transmission line extending between two stations (P, Q) included in a multi-phase electrical power transmission system, in which measurement at least one of the stations is carried out, in each phase, of current (i.sub.R, i.sub.S, i.sub.T) and of voltage (u.sub.R, u.sub.S, u.sub.T) and the measured values are supplied to a travelling wave model by means of which the voltages are obtained at least at two points on the line, comprising:

generating .DELTA.u.sub.Opq as the difference between a change in the zero sequence voltage, calculated with the aid of the travelling wave model, between two consecutive time periods in station Q and the corresponding change in the zero sequence voltage in station P,
generating .DELTA.u.sub.RSpq as the difference between a change in the principal voltage, calculated with the aid of the travelling wave model, between phases R and S between two consectutive time periods in station Q and the corresponding change in the principal voltage in station P,
generating .DELTA.u.sub.Stpq as the difference between a change in the principal voltage, calculated with the aid of the travelling wave model, between the phases S and T between two consecutive time periods in station Q and the corresponding change in principal voltage in station P,
generating .DELTA.u.sub.TRpq as the difference between a change in the principal voltage, calculated with the aid of the travelling wave model, between phases T and R between two consectutive time periods in station Q and the corresponding change in principal voltage in station P,
a fault lying ahead (FF) is indicated when .DELTA.u.sub.Opq is greater than u.sub.Od or when either .DELTA.u.sub.RSpq, .DELTA.u.sub.STpq, or .DELTA.u.sub.TRpq is greater than u.sub.d, where u.sub.Od and u.sub.d are selected levels of detection, and a fault lying behind (BB) is indicated when .DELTA.u.sub.Opq is smaller than -u.sub.Ob or when either .DELTA.u.sub.RSpq, .DELTA.u.sub.STpq or .DELTA.u.sub.TRpq is smaller than -u.sub.b, where -u.sub.Ob and -u.sub.b are selected levels of detection.

2 more elements

A device for the directional detection of a fault on an electrical power transmission line extending between two stations (P, Q) included in a multi-phase electrical power transmission system, which device, located in one of the stations, comprises a travelling wave model, comprising:

a first summation member adapted to generate a difference voltage .DELTA.u.sub.Rp equal to the difference between an R-phase voltage in station P, calculated by means of the travelling wave model, and the corresponding voltage one time period earlier,
a second summation member adapted to generate a difference voltage .DELTA.u.sub.Sp equal to the difference between an S-phase voltage in station P, calculated by means of the travelling wave model, and the corresponding voltage one time period earlier,
a third summation member adapted to generate a difference voltage .DELTA.u.sub.Tp equal to the difference between a T-phase voltage in station P, calculated by means of the travelling wave model, and the corresponding voltage one time period earlier,
a fourth summation member adapted to generate a difference voltage .DELTA.u.sub.Rq equal to the difference between an R-phase voltage in station Q, calculated by means of the travelling wave mode, and the corresponding voltage one time period earlier,
a fifth summation member adapted to generate a difference voltage .DELTA.u.sub.Sq equal to the difference between an S-phase voltage in station Q, calculated by means of the travelling wave model, and the corresponding voltage one time period earlier,
a sixth summation member adapted to generate a difference voltage .DELTA.u.sub.Tq equal to the difference between a T-phase voltage in station Q, calculated by means of the travelling wave model, and a corresponding voltage one time period earlier,
a seventh summation member adapted to generate a numerical value of the change in the zero sequence voltage, 3.vertline..DELTA.u.sub.Op .vertline.==.vertline..DELTA.u.sub.Rp +.DELTA.u.sub.Sp +.DELTA.u.sub.Tp .vertline., in station P,
an eighth summation member adapted to generate a numerical value of the change in the zero sequence voltage, 3.vertline..DELTA.u.sub.Oq .vertline.==.vertline..DELTA.u.sub.Rq +.DELTA.u.sub.Sq +.DELTA.u.sub.Tq .vertline. in station Q,
a ninth summation member adapted to generate a numerical value of the change in the principal voltage between phases T and R, .vertline..DELTA.u.sub.TRp .vertline.=.vertline..DELTA.u.sub.Rp -.DELTA.u.sub.Tp .vertline., in station P,
a tenth summation member adapted to generate a numerical value of the change in the principal voltage between phases R and S, .vertline..DELTA.u.sub.RSp .vertline.=.vertline..DELTA.u.sub.Sp -.DELTA.u.sub.Rp .vertline., in station P,
an eleventh summation member adapted to generate a numerical value of the change in the principal voltage between phases S and T, .vertline..DELTA.u.sub.STp .vertline.=.vertline..DELTA.u.sub.Tp -.DELTA.u.sub.Sp .vertline., in station P,
a twelfth summation member adapted to generate a numerical value of the change in the principal voltage between phases T and R, .vertline..DELTA.u.sub.TRq .vertline.=.vertline..DELTA.u.sub.Rq -.DELTA.u.sub.Tq .vertline., in station Q,
a thirteenth summation member adapted to generate a numerical value of the change in the principal voltage between phases R and S, .vertline..DELTA.u.sub.RSq .vertline.=.vertline..DELTA.u.sub.Sq -.DELTA.u.sub.Rq .vertline., in station Q,
a fourteenth summation member adapted to generate a numerical value of the change in the principal voltage between phases T and S, .vertline..DELTA.u.sub.STq .vertline.=.vertline..DELTA.u.sub.Tq -.DELTA.u.sub.Sq .vertline., in station Q,
a fifteenth summation member adapted to generate a mean value .DELTA.u.sub.Opq of the change in the zero sequence voltage .DELTA.u.sub.Opq ==.vertline..DELTA.u.sub.Oq .vertline.-.vertline..DELTA.u.sub.Op .vertline. between stations P and Q,
a sixteenth summation member adapted to generate a mean value .DELTA.u.sub.STpq of the change in the principal voltage between phases S and T, .DELTA.u.sub.STpq =.vertline..DELTA.u.sub.STq .vertline.-.vertline..DELTA.u.sub.STp .vertline., between stations P and Q,
a seventeenth summation member adapted to generate a mean value .DELTA.u.sub.RSpq of the change in the principal voltage between phases R and S, .DELTA.u.sub.RSpq =.vertline..DELTA.u.sub.RSq .vertline.-.vertline..DELTA.u.sub.RSp .vertline., between stations P and Q,
an eighteenth summation member adapted to generate a mean value .DELTA.u.sub.TRpq of the change in the principal voltage between phases T and R, .DELTA.u.sub.TRpq =.vertline..DELTA.u.sub.TRq .vertline.-.vertline..DELTA.u.sub.TRp .vertline.,
a first comparison element adapted to compare .DELTA.u.sub.TRpq with a selected voltage level u.sub.d and, when .DELTA.u.sub.TRpq is greater than said voltage level, to deliver a logical "1"-signal on its output DTR,
a second comparison element adapted to compare .DELTA.u.sub.TRpq with a selected voltage level -u.sub.b and, when .DELTA.u.sub.TRpq is lower than said voltage level, to deliver a logical "1"-signal on its output BTR,
a third comparison element adapted to compare .DELTA.u.sub.RSpq with a selected voltage level u.sub.d and, when .DELTA.u.sub.RSpq is greater than said voltage level, to deliver a logical "1"-signal on its output DRS,
a fourth comparison element adapted to compare .DELTA.u.sub.RSpq with a selected voltage level -u.sub.b and, when .DELTA.u.sub.RSpq is smaller than said voltage level, to deliver a logical "1"-signal on its output BRS,
a fifth comparison element adapted to compare .DELTA.u.sub.STpq with a selected voltage level u.sub.d and, when .DELTA.u.sub.STpq is greater than said voltage level, to deliver a logical "1"-signal on its output DST,
a sixth comparison element adapted to compare .DELTA.u.sub.STpq with a selected voltage level -u.sub.b and, when .DELTA.u.sub.STpq is smaller than said voltage level, to deliver a logical "1"-signal on its output BST,
a seventh comparison element adapted to compare .DELTA.u.sub.Opq with a selected voltage level u.sub.Od and, when .DELTA.u.sub.Opq is greater than said voltage level, to deliver a logical "1"-signal on its output DO,
an eighth comparison element adapted to compare .DELTA.u.sub.Opq with a selected voltage level -u.sub.Ob and, when .DELTA.u.sub.Opq is smaller than said voltage level, to deliver a logical "1"-signal on its output BO,
a first or-element adapted to deliver on its output (FF) a logical "1"-signal indicating a fault lying ahead when any of DRS, DST, DTR or DO consists of a logical "1"-signal, and
a second or-element adapted to deliver on its output (BB) a logical "1"-signal indicating a fault lying behind when any of BRS, BST, BTR or BO consists of a logical "1"-signal.

25 more elements

Dependencies are inferred from the claim text.