18-03-2011, 10:54 AM
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introduction
A new technique for the protection of transmission systems.
Relays are installed at each bus bar in a transmission network.
Relay contains a fault detection system together with a communication unit.
Relay determine the location of the fault.
Faults
A fault is any abnormal flow of electric current
Possible causes of faults
Lightning strikes near line
Snow storms/icing on lines (can cause lines to sag)
High winds
Bird or other animal contact
•Conductor clash
Location of faults[/b]
Save time and resources for the electric utility industry.
Determine “distance to fault” from a transmission line end.
Aid in fast restoration of power.
Communication systems can retrieve fault location information.
TRAVELING WAVE FAULT LOCATION THEORY
Traveling wave fault locators make use of the transient signals generated by the fault.
Fault location is determined by accurately time tagging the arrival of the travelling wave at each end of the line and comparing the time difference to the total propagation time.
Precisely synchronized clocks are the key element in the implementation of this fault location technique.
The propagation velocity of the traveling wave is roughly 300 meters per microsecond which in turn requires the clocks to be synchronized with respect to each other by less than one microsecond.
The voltage and current at any point x obey the partial differential Equations
∂e/∂x = - L ∂i/∂t
∂i/∂x = - C ∂e/∂t
Where L and C are the inductance and capacitance of the line per unit length.
The solutions of these equations are
e(x, t)=ef(x-vt) + er(x+vt)
i(x, t)=1/z ef(x-vt) - 1/z er(x+vt)
Where Z = Ö(L/C ) is the characteristic impedance of the transmission line and V=1/Ö(LC) is the velocity of propagation. Forward (ef and if) and reverse (er and ir) waves. Wave amplitudes are represented by reflection coefficients ka and kb which are determined by characteristic impedance ratios at the discontinuities
x = {l – c( τa – τb )}/2
‘X’ is the distance to the fault from a substation,τa and τb represent the travel time from the fault to the discontinuity, ‘l’ is the length of the line, ‘c’ is the wave velocity.
WHAT IS GPS?
Global Positioning System (GPS) is a satellite-based navigation system made up of a network of 24 satellites placed into orbit.
2D & 3D positioning is possible
Allows precise determination of location, velocity, direction and time
introduction
A new technique for the protection of transmission systems.
Relays are installed at each bus bar in a transmission network.
Relay contains a fault detection system together with a communication unit.
Relay determine the location of the fault.
Faults
A fault is any abnormal flow of electric current
Possible causes of faults
Lightning strikes near line
Snow storms/icing on lines (can cause lines to sag)
High winds
Bird or other animal contact
•Conductor clash
Location of faults[/b]
Save time and resources for the electric utility industry.
Determine “distance to fault” from a transmission line end.
Aid in fast restoration of power.
Communication systems can retrieve fault location information.
TRAVELING WAVE FAULT LOCATION THEORY
Traveling wave fault locators make use of the transient signals generated by the fault.
Fault location is determined by accurately time tagging the arrival of the travelling wave at each end of the line and comparing the time difference to the total propagation time.
Precisely synchronized clocks are the key element in the implementation of this fault location technique.
The propagation velocity of the traveling wave is roughly 300 meters per microsecond which in turn requires the clocks to be synchronized with respect to each other by less than one microsecond.
The voltage and current at any point x obey the partial differential Equations
∂e/∂x = - L ∂i/∂t
∂i/∂x = - C ∂e/∂t
Where L and C are the inductance and capacitance of the line per unit length.
The solutions of these equations are
e(x, t)=ef(x-vt) + er(x+vt)
i(x, t)=1/z ef(x-vt) - 1/z er(x+vt)
Where Z = Ö(L/C ) is the characteristic impedance of the transmission line and V=1/Ö(LC) is the velocity of propagation. Forward (ef and if) and reverse (er and ir) waves. Wave amplitudes are represented by reflection coefficients ka and kb which are determined by characteristic impedance ratios at the discontinuities
x = {l – c( τa – τb )}/2
‘X’ is the distance to the fault from a substation,τa and τb represent the travel time from the fault to the discontinuity, ‘l’ is the length of the line, ‘c’ is the wave velocity.
WHAT IS GPS?
Global Positioning System (GPS) is a satellite-based navigation system made up of a network of 24 satellites placed into orbit.
2D & 3D positioning is possible
Allows precise determination of location, velocity, direction and time
