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Advanced Monitoring System for Advanced Monitoring System for Health Assessment of Overhead Health Assessment of Overhead

Transmission LinesTransmission Lines

Prof. Rahmat A. ShoureshiPower Systems Engineering Research

Center (PSERC)Colorado School of Mines

rshoures@mines.edu© 2002 Colorado School of Mines

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AcknowledgementAcknowledgementThis project has been supported by:This project has been supported by:

• Electric Power Research Institute- Ray Lings

• Electric de France- Michele Gaudry

• Nebraska Public Power District- David Wolff

• Tri-State Generation & Transmission- Art Mander

• Western Area Power Administration- Paulette Kaptain

“SENSORS”“SENSORS”

Essential Elements For Enhancing System Intelligence

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PSERC Research PSERC Research Thrusts at CSMThrusts at CSM

Intelligent Control Advanced Sensing

Diagnostics PredictiveMaintenance

Large Scale System Analysis

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Initial Problem: Integrity of Ground RisersInitial Problem: Integrity of Ground Risers

IntelligentData

Analysis

Sensory Inputs

Information

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PowerEquipment

PowerPowerEquipmentEquipment

RiserConnection

RiserRiserConnectionConnection

GroundMat GridGroundGround

Mat GridMat Grid

EMAT’sEMAT’sEMAT’sInitialPulse

Defect

Riser

ReflectionPulse from

Defect

Portion ofPulse which

Passes Defect

ReflectionPulse from

Thermoweld

EMAT Transducer ConceptEMAT Transducer Concept

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Torsional Mode in CylindersTorsional Mode in Cylinders

NSNSNS

FB

I

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Torsional Modes

First Order Second Order

twonodes

singlenode

Zero OrderNodes are zero crossings in a Bessel function

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Trapped Torsional ModeTrapped Torsional Mode

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Experimental SetupExperimental Setup

EMAT Pulser/Receiver

Oscilloscope Signal Generator

ReceiverFilter

Activation Pulse

DrivingCycles

Driving Signal

ReceivedSignal

Signature

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Clean Sample

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

-0.0005 -0.0004 -0.0003 -0.0002 -0.0001 0 0.0001

time (sec)

Volts

TX RX

1

1

2 3 4 5 6

2 TX RX

3 TX RX

4 TX RX

5 TX RX

TX RX6

R. A. SHOURESHI 9-27-99

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Early Experimental ResultsEarly Experimental ResultsSignal from Damaged Conductor

-0.25-0.2

-0.15-0.1

-0.050

0.050.1

0.150.2

0.25

3.00E-04 4.00E-04 5.00E-04

Time (us)

Am

plitu

de (V

)

Transducersapplied Here

Signal moves down conductorand reflects off of damage

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Perpendicular Cut

Clean Sample

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

-0.0005 -0.0004 -0.0003 -0.0002 -0.0001 0 0.0001

time (sec)

Vol

ts

10% Cut Perpendicular to Riser Axis

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

-0.0005 -0.0004 -0.0003 -0.0002 -0.0001 0 0.0001

Time (sec)

Vol

ts

25% Cut Perpendicular to Riser Axis

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

-0.0005 -0.0004 -0.0003 -0.0002 -0.0001 0 0.0001

Time (sec)

Vol

ts

50% Cut Perpendicular to Riser Axis

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

-0.0005 -0.0004 -0.0003 -0.0002 -0.0001 0 0.0001

Time (sec)

Volts

R. A. SHOURESHI 9-27-99

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Broken Strands in ACSRBroken Strands in ACSR

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RESEARCH OBJECTIVE:

The main objective of this study is to develop a robust,

portable, intelligent monitoring and diagnostic system

for the health assessment of ACSR strands

in energized transmission lines.

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A Monitoring System Should Be:A Monitoring System Should Be:• Robust to operating and environmental

conditions• Intelligent to analyze data and provide

useful information • Stable enough as to not set false alarms• Easy to use (user friendly)

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A Monitoring System Should Be:A Monitoring System Should Be:(continued)(continued)

• Portable• Easily attachable and detachable• Capable of providing adequate bandwidth• Inexpensive

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Causes of DamageCauses of Damage

• Aeolian Vibration• Galloping• Turbulent Winds• Ice Loading• Other

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21

22

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Present available tools and techniques suffer from

-Accuracy

-Reliability

-Complexity

-Cost

-Required Training

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Technical ApproachTechnical Approach

• Mathematical Analysis• System Design• Laboratory Experimental Design and

Construction• Field Tests

Mathematical Modeling and Mathematical Modeling and Analysis Analysis

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Analytical Modeling Analytical Modeling ––Equations of MotionEquations of Motion

• Consider a straight section of wire rope loaded simultaneously in both tension and torsion:

• where f is the external force and q is the external moment (both per unit of stressed rope lengths)

C

T + T

C + C

f

q

Tz

uS

S

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Orthotropic Sheet Orthotropic Sheet (Layers of Wires) Model(Layers of Wires) Model

1’

2’

1

Cable Axis

α

Strand Axis

Normal AxisWire Strands 2

Orthotropic Sheet parallelwith the Strand axis

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Interwire/Interlayer Interwire/Interlayer Contact ForcesContact Forces

BB

B

B B

B

A

A

A

A

A

A

Line Contact within Layer

A

A

BA

Cross Section Diagramof Wire Rope

Trellis Contact between Layers

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θ : Angle Disp.P : Axial Force

δ : Axial Disp.

αi : i th Strand Lay Angle

Ri : Herical Radius

T : Torsional Moment

Fs,i : i th Strand Force Component

Fs : Total Force induced by Strandsa i : Net Area of i th StrandE i : Young’ Modulus of i th Strandε s,i : Strain of i th Strand

∑ ∑= =

==n

i

n

iisiiiss EaFF

1 1,, ε

+

=

λλθααδαε iiiiis R cossincos 2

,

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Axial Force, AAxial Force, A11 and Aand A22

∑

∑

∑

=

=

=

=

=

+

==

n

iiiiii

n

iiii

n

iiis

REaA

EaA

AAFP

1

22

1

31

121,

sincos

cos

cos

αα

α

θδαλλ

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Torsional Moment, ATorsional Moment, A33 and Aand A44

+

=

+=∑

= λλλθδθα 43

1, sin AAGJFRT

n

iiiiisi

( )∑

∑

=

=

+=

=

n

iiiiiiii

n

iiiiii

GJREaA

REaA

1

224

1

23

sincos

sincos

αα

αα

Ji : Polar Moment of InertiaGi : Shear Modulus

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Formulas for Formulas for Constitutive ConstantConstitutive Constant

∑

∑

∑

∑

=

=

=

=

=

=

=

+

=

n

iiii

n

iiiii

n

iiiii

corecore

n

iii

kRaA

lkRaA

lkRaA

EakaA

1,66

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1,163

1,612

1,111

4

4

4

4

π

π

π

π

)11(:::

::

::

,66

,16

,61

,11

ordirectionlayWireldirectionShearinStiffnessk

StiffnessCoupledkdirectionShear

AxialinStiffnessCoupledkdirectionAxialinStiffnessk

RadiusHelicalRAreaNetWireEacha

i

i

i

i

i

i

i

−

Experimental Analysis of ACSRExperimental Analysis of ACSR

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Experimental SystemExperimental System

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Armor rod

3 cuts & 2 semi-cuts

6 cuts &4 semi-cuts

Abnormal conductor

Normal conductor

1 foot

Transmitter

Receiver

Shoe Aluminum conductor

Experimental Experimental Setup in the LabSetup in the Lab

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370 2 4 6 8 10 12 14 16 18 20

x 10-4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

Signal of Bare Conductor

Time (sec)

Amplitude

380 2 4 6 8 10 12 14 16 18 20

x 10-4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

Signal of Bare Conductor with Small Cut

Time (sec)

Amplitude

390 2 4 6 8 10 12 14 16 18 20

x 10-4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

Signal of Bare Conductor with Large Cut

Time (sec)

Amplitude

400 2 4 6 8 10 12 14 16 18 20

x 10-4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

Bare Conductor Signal Comparison

Time (sec)

Amplitude

Conductor with Small CutBare Conductor

410 2 4 6 8 10 12 14 16 18 20

x 10-4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

Comparison with Larger Cut

Time (sec)

Amplitude

Conductor with Large CutConductor with Small CutBare Conductor

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Field TestsField Tests

• Tri- State Transmission Lines in Nebraska• EPRI High Voltage/High Current and

Environmental Chamber in Lenox, MA• EPRI High Current, High Temperature

facilities in Haslet, TX

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Field Testing of ACSR Field Testing of ACSR Transmission LineTransmission Line

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ConclusionsConclusions

• A portable, non-invasive, and intelligent sensor system for integrity assessment of transmission lines and other conductors has been developed.

• This system can be used on energized lines.• This monitoring system has passed high

voltage, high current, and temperature performance tests at EPRI facilities.

• Prototypes are being made for beta testing at utility facilities.

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Thank YouThank You

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Questions?Questions?