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Partial Discharge Detection and localization
INTRODUCTION
• Partial discharge (PD) phenomenon and features of PD
signals
• Conclusions
• PD localization techniques for Cables
• Localization using Direction of arrival (DOA) of PDs
• DOA based PD localization in branched cable networks
• Sensors for PD diagnostics
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•Localized dielectric breakdown
•Voids, cracks, bubbles or inclusions within insulation
• High voltage stress
Electromagnetic, acoustic, optical and chemical energy emitted away
Partial Discharge (PD) Phenomenon and
Features of PD Signals
•Eletctric field collapses during breakdown and energy is
released
3
Cavity
Cb
Ca
Cc
(a)
Electrode
Healthy
insulation
A
1
2
31
Ua
Uc
di
ds
Metal Plate
Electrodes
Healthy epoxy
resins insulation
Cavity (source
of PD)(b) (c)
Partial Discharge (PD) Phenomenon and
Features of PD Signals
An artificial PD defect Equivalent electrical model
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Partial Discharge (PD) Phenomenon and
Features of PD Signals
i
UaUc
t
t
Ui=Ubc
Ue
• Positive polarity PD pulses during positive cycle of operational voltage
• Negative polarity PD pulses during negative cycle of operational voltage
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Sensors for PD Diagnostics
Electromagnetic, Electrical, acoustic, optical and chemical
Electromagnetic Induction sensor
)(
)(dt
tdiMtV
Here i(t) is the (high frequency)PD current pulse
Sensors should have high bandwidth to detect fast PD pulses 6
PD Localization Techniques for Cables
1- TDR technique uses the reflected pulses from the far end
2- TOA uses incoming pulses captured by two or multiple measuring sensors
3- FAA technique uses attenuation and dispersion features of travelling PD
Frequency and amplitude Distance
Distancetime and velocity
Distancetime and velocity
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Objective of the Paper Objective /Problem of the paper
Multi-section and Multi-path cable network
•Various reflections
•Different interconnected cables separate propagation properties
•Impedance discontinuities for the PD signal
Localization in branched cable networks
i). Identification of the faulty section ii). Localization of fault on identified section
Solution
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Proposed Technique
conventional techniques to locate
the fault point using
TDR, TOA, FAA
Directionally calibrated installed sensors
Polarity of detected pulses
Direction or arrival of PD pulses
Compare with the 2nd consecutive sensor
Identification of the faulty section
Stage I
Identification
of faulty section
Stage II
Localization
Directional of Arrival (DOA)
Polarity of the PD signals
captured by
Directionally calibrated
installed induction sensors
A Bi(t)
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Proposed Technique
A Bi(t)
Determination of DOA of PD pulses
DOA is side A DOA is side B
Positive polarity PD arrival is from face A of the sensor
Negative polarity PD arrival is from face B of the sensor
On-line generated PD pulses
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Proposed Technique
Determination of DOA of PD pulses
Positive polarity PD arrival is from face A of the sensor
Negative polarity PD arrival is from face B of the sensor
PD defect
P2
RC1 RC2
Power
transformer
220 V
220 V / 12 kVP1
L1 L2
CLWound coil for
generating PDs
PA BA B Q
Overhead covered
conductor line
Fault is in between the sensors
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Implementation of Proposed Technique
Experimental setup
Identical sensors
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Implementation of Proposed Technique
100 pF
v
A
A
B
B
B
A
C1_a C1_b
C3_b
C2_b
C3_a
C2_a
Earth screen (copper strips
from shield to ground)
100 pF
Load
PD free MV
transformer
0.230/12KV
0-230V (50 Hz)
variable AC Power
Source
S1S2
S3
PD generating
wound wire
Two cases are experimented on the T-joint cable network
i) The PD fault located at the T-joint area
ii) The PD fault located at one of the branch
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The PD Fault Located at the T-joint Area
Measurement methodology Captured PD pulses
The three sensor shows that the DOA of the PD signal is through face A.
The fault is located at Joint area
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The PD Fault Located at a Cable Branch
Measurement methodology Captured PD pulses
Sensor S2 and S3 detected DOA through their face A and sensor S1
through face B . The PD fault is located at cable C1
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Integration of the PD Localization
Technique
S12
PD defect
J1J2
J3
J4 P5
S21 S22 S31S32 S41
S42 S43
P6
Sensors can be permanently installed around the joints over the whole
Distribution network
Centralized processing of the sensors data, developing the
algorithm, can identify the faulty cable section within the
complex topology network16
Conclusions
Integration of proposed technique as proactive diagnostics of PD
faults can enhance the capabilities of substation and feeder
automation for modern grid of today.
S12
PD defect
J1J2
J3
J4 P5
S21 S22 S31S32 S41
S42 S43
P6
J4 P5
S42 S43
P6
The proposed technique can be integrated over the wider network at suitable
installable locations for network with; cable, CC lines and transformers etc
using low cost induction sensors such as Rogowski coils.
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THANKS
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