fault location in distribution feeders containing distributed generation

Power System 2002 Conference: Impact of Distributed GenerationCLEMSON UNIVERSITY ELECTRIC POWER RESEARCH ASSOCIATION

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Fault Location In Distribution Feeders Containing Distributed Generation

Darla King Adly A. Girgis IEEE Student Member 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– Small, high-speed generator

power units• Consists of a turbine, a

compressor, and a two-pole permanent magnet generator

• Can produce from 25kW-100kW of power by conversion of fossil fuels.

• Fuel Cell– 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

http://www.buildinggreen.com/products/prod_rev_images/capstone.jpg


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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”

• Wind passing over the blades is converted into mechanical power, which is fed through a transmission to an electrical generator

• Solar Energy(Photovoltaic)– Electricity can be produced from

sunlight through a photovoltaics (PV) process

• 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


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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


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Modified Zabc Method

• Solve for Initial Fault Distance: Do (Without any contributions from the DG’s)– Example: Single Line-To-Ground Fault

FC

FB

FA

sC

sB

sA

o

cccbca

bcbbba

acabaa

sC

sB

sA

VVV

III

xDZZZZZZZZZ

VVV

FFAosCacsBabsAaasA RIDIZIZIZV

sAi

sAr

FAisCracsCiacsBrabsBiabsAraasAiaa

FArsCiacsCracsBiabsBrabsAiaasAraa

F

o

VV

IIXIRIXIRIXIRIIXIRIXIRIXIR

RD 1

)()(

)()()()(

FArFAi

FArsAiFAisAro IbIa

IVIVD


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Modified Zabc MethodDj

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

Source

DG3DG2DG1

Idg1

Is

Idg2 Idg3

L1

12.47KV System100MVA BaseL1 = 1.5 milesL2 – L1 = 0.75 milesL3 – L2 = 1.2 miles

L2 – L1 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

– 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%

Source

DG3DG2DG1

Idg1

Is

Idg2 Idg3

Is+Idg1F

Is+Idg1+Idg2 Idg3

L1 L2 – L1 L3 – L2


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Results

• Iteration Process Yielded: Dfinal=3.0426 mi• Compare Dfinal(3.0426 mi) to Dactual(3.05 mi)• % Error = .243 %

Dactual = 3.05 mi

Dfinal = 3.0426 mi


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Results

Source & DG1 DG1 & DG2 DG2 & DG3 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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Questions?

fault location in distribution feeders containing distributed generation

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