GPS (Global Positioning System)
its application in protection scheme
J Shanthan Balaji Reddy
TRAVELING WAVE FAULT THEORY
FAULT LOCATION USING GPS
A new technique for the protection of
Relays are installed at each bus bar in a
Relay contains a fault detection system together
with a communication unit.
Relay determine the location of the fault.
LOCATION OF FAULT
Save time and resources for the electric utility
Determine “distance to fault” from a transmission
Aid in fast restoration of power.
Communication systems can retrieve fault
WHAT IS TRAVELING WAVE FAULT
Faults on the power
transmission system cause
transients that propagate
along the transmission line
These waves have a
propagation velocity &
characteristic impedance ,
travel from fault location
towards line ends
The location of faults is accomplished by precisely
time-tagging wave fronts as they cross a known
point typically in substations at line ends.
Fault location can then be obtained by multiplying
the wave velocity by the time difference in line ends.
TRAVELING WAVE FAULT LOCATION
Traveling wave fault locators make use of the transient signals
generated by the fault.
Unlike other fault location systems, the traveling wave fault
locator is unaffected by load conditions.
Precisely synchronized clocks are the key element in the
implementation of this fault location technique.
The required level of clock accuracy has only recently been
available at reasonable cost with the introduction of the Global
BENEFITS OF TRAVELING WAVE FAULT
Early fault locators used radar.
Radar equipment is typically mobile or located
at substations and requires manual operation.
Traveling wave fault locators are becoming popular
where higher accuracy is important.
GPS-based sub microsecond timing system has proven
reliable in several utility traveling wave projects.
FAULT LOCATION USING GPS
Global Positioning System (GPS)
is a satellite-based navigation
system made up of a network of 24
satellites placed into orbit.
Originally intended for military
Allows precise determination of
location, velocity, direction and
HOW GPS WORKS?
GPS satellites circle the earth
twice a day .
Transmit signal information to
Receivers take this information
and calculate the user's exact
Accurate 3-D location require
OPERATION OF THE FAULT
LOCATION SYSTEM(FLS) USING GPS
A fault locator remote is coupled to
each end of line via CPT.
FL is synchronized to the common
timing standard of UTC from GPS.
Fault resulting produces
The FL remote time tag the
transient arrival times.
By knowing the line length
L and the time-of –arrival
difference (tb - ta ) distance
X can be calculated from
the FL equation:
X=[L-C(tb - ta )]/2
ta & tb are end A and
end B arrival time
c-velocity of light
Protection of transmission line using GPS is
Reliability & availability
Uses a dedicated fault detector to extract
transient signal and GPS system to time tag these signals.
Travelling time of the transient signal from the point of fault to
the adjacent substation is used to determine the fault position.
Proposed technique is able to offer a high accuracy
in fault location.
Unlike traditional protection schemes , this technique offers
a new concept in network protection.
Zhiqian Q Bo Weller, Tom Lomas and Miles A, Redfern
“Positional Protection of Transmission system Using
global Positioning System” IEEE Trans. On Power
delivery, vol15 no 4 oct 2008