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8/9/2019 Om Final Word Seminar
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Power System Protection
Using Global Positioning
System
A Seminar reportsubmitted in partial fulfillment of
the requirements for theDegree of Bachelor of Technology
Under Biju Patnaik University of Technology
by
OM PRAKASH
(Reg. N0.-0601222200)
(2009 2010)
INSTITUTE OF ADVANCED COMPUTER AND RESEARCHPrajukti Vihar, Aurobindo marg, Rayagada -765002(Orissa).
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CERTIFICATE
This is to certify that Mr. OM PRAKASH is a final year / 7th
semester B.Tech student of Electrical & Electronics Engineering
bearing university registration number 0601222200 has been found
satisfactory in the continuous internal evaluation of technical Seminar
entitled Power System Protection Using Global Positioning System
for the requirement of B. Tech. Programme in Electrical & Electronics
Engineering underBiju Patnaik University of Technology, Rourkela,
Orissa for the academic year 2008-2009.
Date: Signature of the
Seminar
coordinator
Date: HOD
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ACKNOWLEDGEMENT
It is my proud privilege to epitomize my deepest sense of gratitude and
indebtedness to the seminar coordinator, Mr. B. Rajanarayan Prusty for his
valuable guidance, keen and sustained interest, intuitive ideas and persistent endeavor.
His inspiring assistance, laconic reciprocation and affectionate care enabled me to
complete my work smoothly and successfully.
I express my gratitude to Mr. Padarobindo Panda, H.O.D., Electrical &
Electronics Engineering for giving me the opportunity and creating a nice work
environment for me to complete my technical seminar report within the stipulated
period of time.
I acknowledge with immense pleasure the sustained interest, encouraging
attitude and constant inspiration rendered by Prof. P. Dinakar, Principal. His
continued drive for better quality in everything that happens at IACR and selfless
inspiration has always helped us to move ahead.
At the nib but not neap tide, I bow my head in gratitude at the omnipresent
Almighty for all his kindness. I still seek his blessings to proceed further.
OM PRAKASH
(0601222200)
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ABSTRACT
Turbine
This is a new technique for the protection of transmission systems by using the
global positioning system (GPS) and fault generated transients. In this scheme the
relay contains a fault transient detection system together with a communication unit,
which is connected to the power line through the high voltage coupling capacitors of
the CVT. Relays are installed at each bus bar in a transmission network. These detectthe fault generated high frequency voltage transient signals and record the time
instant corresponding to when the initial traveling wave generated by the fault arrives
at the busbar.
The decision to trip is based on the components as they propagate through the
system. extensive simulation studies of the technique were carried out to examine the
response to different power system and fault condition. The communication unit is
used to transmit and receive coded digital signals of the local information to and from
associated relays in the system.
At each substation relay determine the location of the fault by comparing the
GPS time stay measured locally with those received from the adjacent substations,
extensive simulation studies presented here demonstrate feasibility of the scheme.
OM PRAKASH (0601222200)
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Protection Of Transmission Line Using GPS
INDEX
1 .ABSTRACT
2 INTRODUCTION
3 TRANSMISSION SYSTEM
4. PROTECTION OF TRANSMISSION SYSTEM
5 TRAVELING WAVE FAULT LOCATION
6 BENEFITS OF TRAVELING WAVE FAULT LOCATION
7 TRAVELING WAVE FAULT LOCATION THEORY
8. POSSIBLE CAUSES OF FAULT
9. WHAT IS GPS?
10. HOW IT WORKS?
11. THE GPS SATELLITE SYSTEM
12. IMPLEMENTATION AND TESTING
13. WHATS THE SIGNAL?
14. HOW ACCURATE IS GPS?
15. SOURCES OF GPS SIGNAL ERRORS
16. CONCLUSION
17. REFERENCES
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INTRODUCTION
Accurate location of faults on power transmission systems can save time and
resources for the electric utility industry. Line searches for faults are costly and can be
inconclusive. Accurate information needs to be acquired quickly in a form most
useful to the power system operator communicating to field personnel.
To achieve this accuracy, a complete system of fault location technology,
hardware, communications, and software systems can be designed. Technology is
available which can help determine fault location to within a transmission span of 300
meters. Reliable self monitoring hardware can be configured for installation sites with
varying geographic and environmental conditions. Communications systems can
retrieve fault location information from substations and quickly provide that
information to system operators. Other communication systems, such as Supervisory
Control and Data Acquisition (SCADA), operate fault sectionalizing circuit breakers
and switches remotely and provide a means of fast restoration. Data from SCADA,
such as sequence of events, relays, and oscillographs, can be used for fault location
selection and verification. Software in a central computer can collect fault information
and reduce operator response time by providing only the concise information required
for field personnel communications. Fault location systems usually determine
distance to fault from a transmission line end. Field personnel can use this data to
find fault locations from transmission line maps and drawings. Some utilities have
automated this process by placing the information in a fault location Geographical
Information System (GIS) computer. Since adding transmission line data to the
computer can be a large effort, some utilities have further shortened the process by
utilizing a transmission structures location database. Several utilities have recently
created these databases for transmission inventory using GPS location
technology and handheld computers.
The inventory database probably contains more information than needed for a
fault location system, and a reduced version would save the large data-collection
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effort. Using this data, the power system operator could provide field personnel direct
location information.
TRANSMISSION SYSTEM
GENERATION TRANSMISSION DISTRIBUTION
Electric power transmission, a process in the delivery of electricity to
consumers, is the bulk transfer of electrical power. Typically, power transmission is
between the power plant and a substation near a populated area.Electricity distribution
is the delivery from the substation to the consumers.Electric power transmission
allows distant energy sources (such as hydroelectric power plants) to be connected to
consumers in population centers, and may allow exploitation of low-grade fuel
resources that would otherwise be too costly to transport to generating facilities. Due
to the large amount of power involved, transmission normally takes place at high
voltage (110 kV or above). Electricity is usually transmitted over long distance
through overhead power transmission lines. Underground power transmission is used
only in densely populated areas due to its high cost of installation and maintenance,
and because the high reactive power produces large charging currents and difficultiesin voltage management.A power transmission system is sometimes referred to
colloquially as a "grid"; however, for reasons of economy, the network is not a
mathematical grid.Redundant paths and lines are provided so that power can be routed
from any power plant to any load center, through a variety of routes, based on the
economics of the transmission path and the cost of power. Much analysis is done by
transmission companies to determine the maximum reliable capacity of each line,
which, due to system stability considerations, may be less than the physical or thermal
limit of the line.
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TRANSMISSION LINE PROTECTION
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WHAT IS TRAVELING WAVE FAULT
LOCATION?
Faults on the power transmission system cause transients that propagate along the
transmission line as waves. Each wave is a composite of frequencies, ranging from a
few kilohertz to several megahertz, having a fast rising front and a slower decaying
tail. Composite waves have a propagation velocity and characteristic impedance andtravel near the speed of light away from the fault location toward line ends. They
continue to travel throughout the power system until they diminish due to impedance
and reflection waves and a new power system equilibrium is reached. The location of
faults is accomplished by precisely time-tagging wave fronts as they cross a known
point typically in substations at line ends. With waves time tagged to sub microsecond
resolution of 30 m, fault location accuracy of 300 m can be obtained. Fault location
can then be obtained by multiplying the wave velocity by the time difference in line
ends. This collection and calculation of time data is usually done at a master station.
Master station information polling time should be fast enough for system operator
needs.
BENEFITS OF TRAVELING WAVE FAULT
LOCATIONEarly fault locators used pulsed radar. This technique uses reflected radar energy to
determine the fault location. Radar equipment is typically mobile or located at
substations and requires manual operation. This technique is popular for location of
permanent faults on cable sections when the cable is de-energized. Impedance-based
fault locators are a popular means of transmission line fault locating. They provide
algorithm advances that correct for fault resistance and load current inaccuracies. Line
length accuracies of 5% are typical for single-ended locators and 1-2% for two-
ended locator systems. Traveling wave fault locators are becoming popular where
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higher accuracy is important. Long lines, difficult accessibility lines, high voltage
direct current (HVDC), and series-compensated lines are popular applications.
POSSIBLE CAUSES OF FAULT
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WHAT IS GPS?
The Global Positioning System (GPS) is a satellite-based navigation system
made up of a network of 24 satellites placed into orbit. GPS was originally
intended for military applications, but in the 1980s, the government made the
system available for civilian use. GPS works in any weather conditions,
anywhere in the world, 24 hours a day. GPS Technology allows precise
determination of location, velocity, direction, and time. GPS are space-based
radio positioning systems that provide time and three-dimensional position
and velocity information to suitably equipped users anywhere on or near the
surface of the earth (and sometimes off the earth).Concept of satellite
navigation was first conceived after the launch of Sputnik 1 in 1957 when
scientists realized that by measuring the frequency shifts in the small bleeps
emanating from this first space vehicle it was possible to locate a point on the
earth's surface.The NAVSTAR system, operated by the US Department of
Defense, is the first such system widely available to civilian users. The
Russian system, GLONASS, is similar in operation and may prove
complimentary to the NAVSTAR system. Current GPS systems enable users
to determine their three dimensional differential position, velocity and time.By
combining GPS with current and future computer mapping techniques, we will
be better able to identify and manage our natural resources. Intelligent vehicle
location and navigation systems will let us avoid congested freeways andmore efficient routes to our destinations, saving millions of dollars in gasoline
and tons of air pollution. Travel aboard ships and aircraft will be safer in all
weather conditions. Businesses with large amounts of outside plant (railroads,
utilities) will be able to manage their resources more efficiently, reducing
consumer costs.
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HOW IT WORKS?
GPS satellites circle the earth twice a day in a very precise orbit and transmit
signal information to earth. GPS receivers take this information and use
triangulation to calculate the user's exact location. Essentially, the GPS
receiver compares the time a signal was transmitted by a satellite with the
time it was received. The time difference tells the GPS receiver how far away
the satellite is. Now, with distance measurements from a few more satellites,
the receiver can determine the user's position and display it on the unit's
electronic map. By knowing the distance from another satellite, the possible
positions of the location are narrowed down to two points (Two intersecting
circles have two points in common). A GPS receiver must be locked on to the
signal of at least three satellites to calculate a 2D position (latitude and
longitude) and track movement. With four or more satellites in view, the
receiver can determine the user's 3D position (latitude, longitude and altitude).
Once the user's position has been determined, the GPS unit can calculate
other information, such as speed, bearing, track, trip distance, distance to
destination, sunrise and sunset time and more.Accurate 3-D measurements
require four satellites. To achieve 3-D real time measurements, the receivers
need at least four channels.
CHAPTER 11
THE GPS SATELLITE SYSTEM
The 24 satellites that make up the GPS space segment are orbiting the earth
about 12,000 miles above us. They are constantly moving, making two
complete orbits in less than 24 hours. These satellites are traveling at speeds
of roughly 7,000 miles an hour. GPS satellites are powered by solar energy.
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They have backup batteries onboard to keep them running in the event of a
solar eclipse, when there's no solar power. Small rocket boosters on each
satellite keep them flying in the correct path.
Here are some other interesting facts about the GPS satellites (also called
NAVSTAR, the official U.S. Department of Defense name for GPS):
The first GPS satellite was launched in 1978.
A full constellation of 24 satellites was achieved in 1994.
Each satellite is built to last about 10 years. Replacements are
constantly being built and launched into orbit.
A GPS satellite weighs approximately 2,000 pounds and is about 17feet across with the solar panels extended.
Transmitter power is only 50 watts or less.
CHAPTER 12
IMPLEMENTATION AND TESTING
Evaluation of the fault locator involved the installation of GPS timing receivers at
four 500kV substations, see Figure 2.0. A especially developed Fault Transient
Interface Unit (FTIU) connects to the transmission lines and discriminates for a valid
traveling wave. The FTIU produces a TTL-level trigger pulse that is coincident with
the leading edge of the traveling wave. A time-tagging input function was provided
under special request to the GPS receiver manufacturer. This input accepts the TTL
level logic pulse from the FTIU and time tags the arrival of the fault-generated
traveling wave. The time tag function is accurate to within 300 nanoseconds of UTC -
well within the overall performance requirement of timing to within 1 microsecond.
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DISTORTION AND ATTENUATION
OF TRAVELING WAVES
The accuracy of fault location depends on the ability to accurately time tagging the
arrival of the traveling wave at each line terminal. The traveling wave once generated,
is subject to attenuation and distortion as it propagates along the transmission line.
Attenuation occurs due to resistive and radiated losses. Distortion of the waveform
occurs due to a variety of factors including bandwidth limitations of the transmission
line, dispersion from different propagation constants of phase-to-phase and phase-to-
ground components, etc. These effects combine to degrade the quality of the "leading
edge" of he traveling wave at large distances from the fault inception point. The
accuracy of time tagging the traveling wave diminishes for the substations far away
from the fault. Experience with the evaluation system has shown that the traveling
wave is relatively "undistorted" for distances less than 350 km. To effectively reduce
the effects of attenuation and distortion requires traveling wave detector installations
spaced at regular intervals. For B.C. Hydro, this translates to installing fault location
equipment at fourteen out of nineteen 500 kVsubstations.
Fault Locator System Test
Calculated cumulative arc length from NIC substation to the fault = 13 1,694.5
meters.
Fault Locator Difference
Output from Est. Value
Test (meters) (meters)
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Fault Locator Response to Traveling Waves Generated by Routine Switching ofSubstation Equipment
Line Estimated Tp Measured Tp
The distance to the fault fromthe line terminals is given by:
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Where Vp is the velocity of propagation for the line and
Denotes stations with travelling wavedetector installations
Figure 2.0 Fault Locator Lnstallations and Testing
HOW ACCURATE IS GPS?
Today's GPS receivers are extremely accurate, thanks to their parallel multi-channel
design. 12 parallel channel receivers are quick to lock onto satellites when first turned
on and they maintain strong locks, even in dense foliage or urban settings with tall
buildings. Certain atmospheric factors and other sources of error can affect the
accuracy of GPS receivers. GPS receivers are accurate to within 15 meters on
average. Newer GPS receivers with WAAS(Wide Area Augmentation System)
capability can improve accuracy to less than three meters on average. No additionalequipment or fees are required to take advantage of WAAS. Users can also get better
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accuracy with Differential GPS (DGPS), which corrects GPS signals to within an
average of three to five meters. The U.S. Coast Guard operates the most common
DGPS correction service. This system consists of a network of towers that receive
GPS signals and transmit a corrected signal by beacon transmitters.
CONCLUSION
Thus the use of GPS in protection of transmission systems is beneficial withrespect to
Value regarding programmatic goals:more reliable monitoring using GPSrelated technologies.
Technical merit: new fault location algorithm based on new input data.
Emphasis on transfer of technology:CCET partnership aimed atcommercialization.
Overall performance:on time, with all goals met so far.
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REFERENCES
www.wikipedia.com
www.howstuffworks.com
www.tycho.usno.org
IEEE JOURNAL
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