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Transcript of Medida de Descargas Parciais Omicron
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7/27/2019 Medida de Descargas Parciais Omicron
1/10
iagnostic Measurements on Powerransformers
Michael Krger e Marcelo Paulino - Soaulo maio/2010 1
INTRODUCTION INTO PARTIAL DISCHARGE (PD)PHENOMENA AND PD MEASUREMENT
Dr. Michael Krger
May 10 PAGE 2
Introduction
Partial Discharges (PD)
"localized electrical discharges that only partially
bridge the insulation between conductors" [IEC 60270:2000]
can harm insulation systems generate electromagnetic signals
PD Measurement
General specifications: IEC 60270:2000o Transformers: IEC 60076 (and others)
detection of critical defects
recognition of defects
assessment of risk
measurable
May 10 PAGE 3
PD Inception and Extinction Voltage
Internal PD hashystersis
External coronahas normally nohysteresis
IEC 60034-27
May 10 PAGE 4
PD Classification
a) corona discharge b) surface discharges
c) discharge in laminated material d) cavity discharge
e) treeing
May 10 PAGE 5
Electrical Treeing in PE
May 10 PAGE 6
Electrical Treeing in PE
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iagnostic Measurements on Powerransformers
Michael Krger e Marcelo Paulino - Soaulo maio/2010 2
May 10 PAGE 7
Chemical (DGA)
Optical (e.g. UV camera for corona)
Electrical (narrow band or wide band)according to IEC 60270
Acoustical
UHF
Detection of PD
May 10 PAGE 8
Equivalent Circuit Diagram
Uz
U1(t)
Ut(t)
U'1(t)-Uz
tUL-UL
FCUq .1=
I1(t)
t
B
A
CP
CS
CF
R1
SI1(t)
Ut
U1
Is(t)
I2(t)I3(t)
B
A
r0CP/2 CP/2
2CS
2CS
CF
= dttiq ).(1
May 10 PAGE 9
Apparent Charge
Apparent charge q, of a pulse is that charge
which, if injected between the terminals of the
test object, would give the same reading on
the measuring instrument as the PD current
pulse itself.
Expressed usually in pC.
The apparent charge is not equal to theamount of charge locally involved at the site
of the discharge, which can not measured
directly.
May 10 PAGE 10
When to measure?
Factory test:
Standard measurement during the AC withstand testfor every new (or repaired) transformer. Usually lowground noise level.
On-site test:
After indication of DGA results.
Usually high ground noise level and other disturbances.
May 10 PAGE 11
The classical visualization
May 10 PAGE 12
PRPD Phase Resolved Histogram
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iagnostic Measurements on Powerransformers
Michael Krger e Marcelo Paulino - Soaulo maio/2010 3
May 10 PAGE 13
Calibration of the PD Instrument
CK
Z
CtU ~A
B
I(t)
U0
C0
Calibrator
Cc
ZmUmMeasuringImpedanc
e
M
Amp. Filter
qks .max
=
Smax
Q = C * U
May 10 PAGE 14
Transformerunder test
Couplingcapacitor
Conventional Coupling of the MeasuringDevice
Testingtransformer
IPD
PD
Fault (discharge)
May 10 PAGE 15
Typical PD Measurement in a Test Lab
Testing transformer
Test object
Coupling capacitor
Faraday cage
PD instrument
May 10 PAGE 16
NoiseFiltering
- High bandwidth desirable for sensitive measurement andhigh pulse repetition rates
- Low bandwidth improves interference rejection
- Always use the highest possible bandwidth
- Only a variable filter is suitable for on-site measurements
May 10 Page: 17
Analogue and Digital PD measuring instruments
PD systems
Analogue PD measuringinstrument
May 10 PAGE 18
Traditional PD Measurement
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iagnostic Measurements on Powerransformers
Michael Krger e Marcelo Paulino - Soaulo maio/2010 4
May 10 PAGE 19
"Digital" PD Measurement withAnalogue Filter
May 10 PAGE 20
"Digital" PD Measurement with Multi-Channels and MUX
May 10 PAGE 22
MPD 600 True Digital Measurement withDigital Filtering
May 10 Page: 24
Synchronous Multi-Channel PD MeasurementSystem MPD600
May 10 PAGE 26
Synchronous multi-channel
measurement
May 10 PAGE 27
Separation of PD and Corona Sources at
Different Locations with 3PARD
3PARD = Three Phase Amplitude Relation Diagram
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iagnostic Measurements on Powerransformers
Michael Krger e Marcelo Paulino - Soaulo maio/2010 5
May 10 PAGE 28
Inner PD source in L1 in 3PARD
L1
L2
L3
L1
L2
L3
Inner PD SourceL1>L2>L3
3PARD
timeframe1 s
Inner PD Source in
L1
5
3PARD = Three Phase Amplitude Relation Diagram
May 10 PAGE 29
L2
L3
3PARD
L1
L1
L2
L3
Outer NoiseL1 L2 L3
timeframe1 s
Outer Noise
6
Outer noise in 3PARD
3PARD = Three Phase Amplitude Relation Diagram
May 10 PAGE 30
3PARD
May 10 PAGE 31
Back Transformation
May 10 PAGE 32
PD source 1 PD source 2 PD source 3
FFT pulse 1
FFT pulse 2
FFT pulse 3
FFT of all three impulses
MPD600
Frequency 2
Frequency 1Frequency 3
PD source 2
PD source 3
PD source 1Frequency 3F re qu en cy 1 F re qu en cy 2
3CFRD 3 Center Frequency
Relation Diagram
May 10 PAGE 33
Measurement at Three Different Frequencies
with 3CFRD
Faulty joint
Needle
Surfacedischarge
22kV_Corona_Surface_Joint
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iagnostic Measurements on Powerransformers
Michael Krger e Marcelo Paulino - Soaulo maio/2010 6
May 10 PAGE 34
Case Studies
PD Measurements on Power Transformers
Coupling of the Measuring System
May 10 PAGE 37
Coupling of the PD Measurement Instrumentto the HV Bushing Measuring Tap
MPD600
May 10 PAGE 38
Power Transformer 132kV/32kV inthe Factory
May 10 PAGE 39
PD Decoupling at the Measuring Tap ofthe HV Bushing
May 10 PAGE 40
PD Decoupling at the Measuring Tap
of the HV Bushing
Advantage
Little constructive effort
No coupling capacitors necessary
Drawback
Measuring tap not always
accessible / existing
May 10 PAGE 41
PD Decoupling by Coupling
Capacitors
MPD600
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iagnostic Measurements on Powerransformers
Michael Krger e Marcelo Paulino - Soaulo maio/2010 7
May 10 PAGE 42
PD Decoupling by CouplingCapacitors
May 10 PAGE 43
PD Decoupling by CouplingCapacitors
May 10 PAGE 44
HV Connections PD free!
May 10 PAGE 45
Inductive PD Decoupling at Cable Screen
May 10 PAGE 46
Capacitive Sensors
Sensor for capacitive coupling(Patented by the University of Hannover)
MPD 600
MPD 600
MPD 600
May 10 PAGE 47
Practical Examples
PD Measurements on Power Transformers
Measuring Results
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iagnostic Measurements on Powerransformers
Michael Krger e Marcelo Paulino - Soaulo maio/2010 8
May 10 PAGE 48
Measuring Results
30 MVA Transformer, 115 kV / 11.3 kV
May 10
Page 49
Synchronous Multi-Channel PD Measurementon a 30MVA 115 / 11.3 kV Transformer
May 10 PAGE 50
Decoupling of PD at the Neutral
May 10 PAGE 51
Measuring Results
30 MVA Transformer, 115 kV / 11.3 kV
Statistical Noise
External Disturbance
PD Fault
May 10
Page 52
Transformer with Coupling Capacitors,
Step-up Transformer and Diesel Generator
Coupling capacitorwith MPD 600 on U
Step-up transformer400V / 21kV
DieselGenerator
Transformer
UVW
May 10
Page 53
Simultaneous PD Measurement on
3 Phases
without 3PARDfiltering
with3PARD
filtering
U
V
W
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iagnostic Measurements on Powerransformers
Michael Krger e Marcelo Paulino - Soaulo maio/2010 9
May 10
Page 54
PD source 1 PD source 2 PD source 3
FFT pulse 1
FFT pulse 2
FFT pulse 3
FFT of all three impulses
MPD600
Frequency 2
Frequency 1Frequency 3
PD source 2
PD source 3
PD source 1Frequency 3F re qu en cy 1 F re qu en cy 2
3CFRD 3 Center FrequencyRelation Diagram
May 10
Page 55
Simultaneous PD Measurement at 3Different Center Frequencies, Phase U
3MHz
300kHz10MHz
withoutfiltering
withfiltering
3MHz
300kHz
10MHz
May 10
Page 56
Decrease of the PD Amplidude withIncreasing Frequencies
PD is not close to themeasurement point (bushing)
10MHz3MHz
May 10 PAGE 6114.05.2010OMICRON Energy Page 61
Combined UHF and IEC Measurements
May 10 PAGE 6214.05.2010OMICRON Energy Page 62
Connection to
the MeasuringTap of theBushing
May 10 PAGE 6314.05.2010OMICRON Energy Page 63
UHF Sensor at the Main Valve
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iagnostic Measurements on Powerransformers
Michael Krger e Marcelo Paulino - So
May 10 PAGE 64
The OMICRON mtronix Solution
May 10 PAGE 65
The OMICRON mtronix Solution
May 10 PAGE 66
Combined UHF and IEC measurement
IEC PD Measurement UHF PD Measurement
Corrected IEC PD Measurement
+
May 10 PAGE 67
Summary
Partial Discharges (PD) can lead to outages
PD measurement is reasonable tool for
diagnosis and quality control
Sensitive PD measurements: High demands on
PD measuring system
MPD600: a variable tool for all kind of
application electrical equipment (cable, transformer, rot.
machines, )
measuring condition (laboratory, factory, on-site)
May 10 PAGE 68
T
hankYouforYourkind
a
ttention!
