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Fault Location In Distribution Feeders
Containing Distributed Generation
Darla King
IEEE Student Member
Power System 2002 Conference: Impact of Distributed Generation
CLEMSON UNIVERSITY ELECTRIC POWER RESEARCH ASSOCIATION
Adly A. Girgis
IEEE Fellow
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Outline
•
•
•
•
•
Introduction of DG
A Modified Fault Location Method?
Overview of the Modified Zabc Method
Analysis
Future Research
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Distributed Generation
• Microturbine
• Fuel Cell
– Small, high-speed generator
power units
• Consists of a turbine, a
compressor, and a twopole permanent magnet
generator
• Can produce from 25kW100kW of power by
conversion of fossil fuels.
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– Produces energy in the
form of electricity and heat
as long as fuel is supplied
– A fuel cell does not run
down or require recharging
• Consists of two electrodes
around an electrolyte
• Oxygen passes over one
electrode and hydrogen
over the other, generating
electricity, water and heat
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Distributed Generation
• Wind Energy
– Wind generators produce
power depending on wind
speed.
– The wind is an indirect form of
solar energy, and is therefore
“renewable”
• Solar Energy(Photovoltaic)
– Electricity can be produced from
sunlight through a photovoltaics
(PV) process
• Wind passing over the blades
is converted into mechanical
power, which is fed through a
transmission to an electrical
generator
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• solid-state electronic cell produces
direct current electrical energy
from the radiant energy of the sun.
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Why Is There The Need For A
Modified Fault Location Method?
• Introduction of Distributed Generation in
Distribution Systems
– Unidirectional to Multi-directional power flow
– Need modified method to eliminate errors inherent
with using older fault location techniques that do
not account for distributed generation
Power System 2002 Conference: Impact of Distributed Generation
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6
Zabc Method?
• What is Zabc Method?
– Uses Three-phase
components
– Based on Steady-State
Analysis During Fault
Conditions
• Why Choose Zabc Method?
– Can be Applied to Balanced
and Unbalanced Systems
• Does not assume ideally
transposed lines
• Does not assume mutual
coupling between phases
are equal
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Modified Zabc Method
Power System 2002 Conference: Impact of Distributed Generation
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Modified Zabc Method
VsA   Z aa
 =
VsB   Z ba
VsC   Z ca
Z ab
Z bb
Z cb
 I sA  V FA 
Z ac 

 +

Z bc  xDo  I sB  V FB 
 I sC  V FC 
Z cc 
• Solve for Initial Fault Distance: Do
(Without any contributions from the DG’s)
– Example: Single Line-To-Ground Fault
VsA = [Z aa I sA + Z ab I sB + Z ac I sC ]Do + I FA RF
D 
 o =
R F 
 (R I - X I + R I - X I + R I - X I ) I  -1 V 
aa sAi
ab sBr
ab sBi
ac sCr
ac sCi
FAr
 aa sAr
  sAr 
 (R aa IsAi + X aa IsAr + R ab IsBi + X ab IsBr + R ac IsCi + X ac IsCr ) IFAi  VsAi 
(VsAr  I FAi ) - (VsAi  I FAr )
Do =
(a  I FAi ) - (b  I FAr )
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Modified Zabc Method
Dj
Calculate Fault Location Voltage : VFabc
Calculate Currents Fed From the DG’s : IDGj
Update Fault Current : IF(j+1) = IFj + IDGj
Calculate New Distance : D(j+1)
Compare Dj and D(j+1)
| D(j+1) – Dj | < 0.1%
Distance to Fault = D(j+1)
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System
Is
Source
Idg1
Idg2
DG1
L1
Idg3
DG2
L2 – L1
12.47KV System
100MVA Base
L1 = 1.5 miles
L2 – L1 = 0.75 miles
L3 – L2 = 1.2 miles
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DG3
L3 – L2
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Data Preparation
• Pick a Particular Fault Location along the Line
• Fault Analysis
– Find Source Voltages
– Find Source Currents
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Analysis
• Zabc Method
– Solve for Initial Distance to Fault
– Continue Iterative Process until Final Distance
to Fault is Found
– Compare Distance Found to Actual Distance
– Determine Accuracy of Zabc Method
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Analysis
• Single Line-To-Ground Fault
– Zabc Method
• Split System into 4 Sections
–
–
–
–
F
Is
Is+Idg1
Is+Idg1+Idg2
Idg3
Source
Idg1
DG1
L1
Idg2
Idg3
DG2
L2 – L1
DG3
L3 – L2
Do < L1
L1 < Do < L2
L2 < Do < L3
Do > L3
• Solve For VFabc
• Find All DG currents
• Find new fault current :
IF(j+1)=IFj+IDGj
• Calculate new fault distance:D(j+1)
• Repeat until D(j+1) – Dj < 0.1%
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Results
Dactual = 3.05 mi
Dfinal = 3.0426 mi
• Iteration Process Yielded: Dfinal=3.0426 mi
• Compare Dfinal(3.0426 mi) to Dactual(3.05 mi)
• % Error = .243 %
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Results
Source & DG1
DG1 & DG2
DG2 & DG3
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Past DG3
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Future Research
• Reduce Errors in Fault Location Method Due to
the Availability of Fault Data on Distribution
Lines
– Method based on Voltage and Current Data at
Beginning of Faulted Line Segment
• Consider Larger System and Account for Loads
– Test Zabc Method with new system
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Future Research
• Construct Algorithm to convert the voltage and
current waveforms into phasor quantities needed
for fault location method
– Use an Electromagnetic Transients Program to simulate
the voltage and current waveforms during fault
conditions
– Obtain Actual Recorded Data from a Fault Recorder
• Test Zabc Method with Simulated Data and Actual
Data
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18
Questions?
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