Transcript On-Line Monitoring of Bushings and PD

New Diagnostic Tools for
High Voltage Bushings
Dr. Michael Krüger, OMICRON Austria
Cigre A2.37 Transformer Failure Statistics
2690 Transformers with 23800 service hours in Germany,
Austria, Switzerland and the Netherlands
Bushings
11.6%
Source: Tenbohlen et. al.: „ ASSESSMENT OF POWER TRANSFORMER RELIABILITY” ISH 2011
Annual Convention 2012 – Eilat, Israel
PAGE 2
Isolation Systems of High Voltage Bushings
RBP
OIP
1913 to 1974
RIP
since 1950
since 1960
Recommended measures
Time schedule
Visual check – leakage and mechanical damage
In case of maintenance work
Measurement of capacitance and
dielectric dissipation factor
- after installation as reference for later measurements
(fingerprint)
- 10 years after commissioning
- dependend on results after each 5 years
(uncritical values) or shorter
Source: B. Heil (HSP Troisdorf, Germany), „Diagnose und Bewertung von Durchführungen“, OMICRON AWT Germany 2010
Annual Convention 2012 – Eilat, Israel
PAGE 3
Definitions of Dielectric Losses
Dielectric losses are caused by
Parallel
Serial
Serial
Parallel
Parallel
Serial
Sum
2.50E-03
2.50E-03
• Conductive losses
2.00E-03
2.00E-03
• Polarization losses
1.50E-03
1.50E-03
• Partial discharges
1.00E-03
1.00E-03
1.00E-03
5.00E-04
5.00E-04
5.00E-04
0.00E+00
0.00E+00
0.00E+00
0
00
50
50
50
100
100
100
Parallel circuit
P F: cos 
| I RP |
1

| I CP | RP    CP
| I RP |
| I tot |
CP
Annual Convention 2012 – Eilat, Israel
200
200
200
250
250
250
300
300
300
350
350
350
Serial circuit
•
DF : t an 
150
150
150
RP
PAGE 5
DF : tan 
UR
 RS    CS
UC
PF: cos 
UR
U tot
RS
CS
400
400
Standards
Type
Main insulation
RIP
Resin
impregnated
paper
DF / tan delta (20°C,
< 0.7 %
IEC60137)
OIP
Oil
impregnated
paper
< 0.7 %
RBP
Resin bonded
paper
< 1.5 %
PF cos phi (20°C,
IEEE C57.19.01)
< 0.85 %
< 0.5 %
<2%
Typical new values
0.3-0.4 %
0.2-0.4 %
0.5-0.6 %
PD (IEC60137) at Um
1.5 Um /3
1.05 Um /3
< 10 pC
< 5 pC
< 5 pC
< 10 pC
< 5 pC
< 5 pC
< 300 pC
Annual Convention 2012 – Eilat, Israel
PAGE 6
Cigre WG A2.34 Brochure 445
Guide for Transformer Maintenance
www.e-cigre.org
Frequency
Annual Convention 2012 – Eilat, Israel
PAGE 10
RBP - Bushings
• Not free of cavities – Partial Discharges
possible also at rated voltage
• Higher dielectric losses can feed to thermal
instability
• RPB has cavities and cracks in the
paper which are normally filled
with the surrounding oil
• Increase of capacitance
• After a longer storage period this oil is running
out. The PD level is increasing and the
capacitance is getting smaller
Annual Convention 2012 – Eilat, Israel
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Mesurement on 220kV RBP Bushings (1971)
Annual Convention 2012 – Eilat, Israel
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TanDelta 15-400Hz
Annual Convention 2012 – Eilat, Israel
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RBP Bushing Oil-filled Cracks
Annual Convention 2012 – Eilat, Israel
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RBP Bushing 123kV (1963)
•PF (f) A, B, C
•1.2%
Influence of
Moisture
•1.0%
•0.8%
•A
•0.6%
•0.4%
Annual Convention 2012 – Eilat, Israel
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•450.0Hz
•400.0Hz
•350.0Hz
•300.0Hz
•250.0Hz
•200.0Hz
•150.0Hz
•100.0Hz
•0.0Hz
•0.0%
•50.0Hz
•0.2%
RBP Bushing 123kV
?
Annual Convention 2012 – Eilat, Israel
PAGE 16
RBP Bushing 123kV
PF (V) A, B, C
1.1%
1.0%
0.9%
A
B
0.8%
C
0.7%
Annual Convention 2012 – Eilat, Israel
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14000.0V
12000.0V
10000.0V
8000.0V
6000.0V
4000.0V
2000.0V
0.5%
0.0V
0.6%
RBP Bushing 123kV
PF (f) A, B, C
2.5%
2.0%
A
1.5%
B
1.0%
C
Annual Convention 2012 – Eilat, Israel
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450.0Hz
400.0Hz
350.0Hz
300.0Hz
250.0Hz
200.0Hz
150.0Hz
100.0Hz
50.0Hz
0.0%
0.0Hz
0.5%
RBP Bushing 123kV
Bushing has to be
exchanged
defective contact on the
measuring tap or
defective connection between the
innermost layer and the HV
conductor or
partial breakdown between layers
Annual Convention 2012 – Eilat, Israel
PAGE 19
Innermost Layer Was Not Properly
Connected to the HV Conductor.
Annual Convention 2012 – Eilat, Israel
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123kV RBP Bushing
Annual Convention 2012 – Eilat, Israel
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Dissipation Factor Measurement
DF (f) A, B, C
8.0%
7.0%
A
6.0%
5.0%
4.0%
B
3.0%
2.0%
C
1.0%
Annual Convention 2012 – Eilat, Israel
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450.0Hz
400.0Hz
350.0Hz
300.0Hz
250.0Hz
200.0Hz
150.0Hz
100.0Hz
50.0Hz
0.0Hz
0.0%
Aktivteil
Annual Convention 2012 – Eilat, Israel
PAGE 26
OIP Bushings
•
Paper of the OIP bushings ages particularly
at high temperatures
•
Through aging the dielectric losses will
increase
-> this increases the power factor
•
Temperature dependent aging decomposes
the Paper and produces additional water
-> this accellerates the aging
Annual Convention 2012 – Eilat, Israel
PAGE 27
Breakdown in a OIP Bushing
Source: B. Heil, „Diagnose und Bewertung von Durchführungen”, OMICRON AWT Dresden 2010
Annual Convention 2012 – Eilat, Israel
PAGE 28
33kV OIP Bushings
Removed
bushings
New bushings
C-Tan-Delta Meas.
Annual Convention 2012 – Eilat, Israel
PAGE 29
Tan Delta (T) at 50Hz (OIP DF)
10.00
0.1-0.3% Water in paper
[%]
0.4-0.6% Water in paper
1% Water in paper
1.00
0.10
20
30
40
50
60
Source: ABB, Bushing diagnostics and conditioning
Annual Convention 2012 – Eilat, Israel
PAGE 30
70
80
°C
90
Tan Delta (f) at 30°C (33kV OIP DF)
Tan Delta (f) A, B, C
%
1.8
A
B
C
A Removed
B Removed
C Removed
1.6
1.4
1.2
1.0
0.8
0.6
0.4
Annual Convention 2012 – Eilat, Israel
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Hz
450
400
350
300
250
200
150
100
50
0.0
0
0.2
123kV OIP Bushings TanDelta = f(U)
PF (V) A, B, C
1.3%
1.2%
1.1%
1.0%
A
B
C
0.9%
0.8%
0.7%
0.6%
0.5%
Annual Convention 2012 – Eilat, Israel
PAGE 32
14000.0V
12000.0V
10000.0V
8000.0V
6000.0V
4000.0V
2000.0V
0.0V
0.4%
123kV OIP Bushings TanDelta = f(f)
Annual Convention 2012 – Eilat, Israel
PAGE 33
123kV OIP DF Corroded Measuring Tap
Annual Convention 2012 – Eilat, Israel
PAGE 34
Aging of RIP Bushings
•
Partial breakdowns between capacitive layers are rather
seldom
•
Decrease of the power factor with increasing test voltage
can be an indicator for partial breakdowns
•
Also defective connections of the measurement layer to
the test tap or of the innermost layer to the high voltage
conductor may be the reason for a decrease of the power
factor with increasing test voltage
•
Increase of the capacitance after a partial breakdown
between two layers:
•
Cnew = Cold x n / (n-1)
n= number of layers approx. 4-7 kV per layer
Annual Convention 2012 – Eilat, Israel
PAGE 35
RIP Bushing on a HVDC Transformer
Source: SIEMENS AG
Annual Convention 2012 – Eilat, Israel
PAGE 36
RIP Bushing
Annual Convention 2012 – Eilat, Israel
PAGE 37
Partial Breakdown on a RIP Bushing
Source: B. Heil, „Diagnose und Bewertung von Durchführungen”, OMICRON AWT Germany 2010
Annual Convention 2012 – Eilat, Israel
PAGE 38
220kV RIP Bushing, Stored Outside
Annual Convention 2012 – Eilat, Israel
PAGE 39
220kV RIP Bushing, Stored Outside
0.85 %
after removing from TR
3 months after removing
0.75 %
Tan Delta
0.65 %
Minimum
6 months afetr removing
0.55 %
0.45 %
Minimum
0.35 %
0.25 %
0.0 Hz
Minimum
100.0 Hz
Annual Convention 2012 – Eilat, Israel
200.0 Hz
PAGE 40
300.0 Hz
400.0 Hz
500.0 Hz
Moisture in RBP and RIP Bushings
• The oil side of RBP and RIP bushings
doesn't need a housing
• Cellulose near to the surface can absorb
water, if bushings are not stored properly
• Incoming water, also from the ambient air
reduces the dielectric strength – this
causes an increase of the dielectric
dissipation factor
Annual Convention 2012 – Eilat, Israel
PAGE 41
Water in RBP and RIP Bushings
•Drying of RBP
and RIP bushings
is limited
RIP wet
Annual Convention 2012 – Eilat, Israel
RIP dry
PAGE 42
Measurement of the Dielectric Response
with FDS und PDC
PDC
FDS
Combination of
PDC und FDS
reduces
measurement time
Annual Convention 2012 – Eilat, Israel
PAGE 43
Combined FDS-PDC Measurement
on a RIP Bushing
Annual Convention 2012 – Eilat, Israel
PAGE 44
FDS Results on RIP, RBP and OIP Bushings
RIP
OIP
Annual Convention 2012 – Eilat, Israel
PAGE 45
RBP
FDS/PDC on a RIP Bushing at Different
Temperatures
60°C
50Hz tanδ
25°C
Source: G. Kopp, „Measurement of the dielectric response on HV bushings “
Annual Convention 2012 – Eilat, Israel
PAGE 46
FDS/PDC with Dry and Wet Surface
wet surface
50Hz tanδ
equal
dry surface
Source: G. Kopp, „ Measurement of the dielectric response on HV bushings “
Annual Convention 2012 – Eilat, Israel
PAGE 47
Drying of a 145kV RBP Bushing
TanDelta Measurement
Annual Convention 2012 – Eilat, Israel
PAGE 48
Drying of a 145kV RBP Bushing
TanDelta (V)
2.5%
2.0%
•1. Measurement before drying
Drying:
1.5%
1200h at 90°C / 200°F
1.0%
•2. Measurement after drying
0.5%
0.0%
0
2
4
6
8
10
12
14
TanDelta (f)
kV
3.5%
3.0%
2.5%
2.0%
•1. Measurement before drying
1.5%
1.0%
0.5%
•2. Measurement after drying
0.0%
0
50
100
150
200
250
Hz
Annual Convention 2012 – Eilat, Israel
PAGE 49
300
350
400
450
High Voltage Test with PD Measurement
Annual Convention 2012 – Eilat, Israel
PAGE 50
PD Measurement - Phase Resolved
Pattern @ 157kV
Annual Convention 2012 – Eilat, Israel
PAGE 51
Separation of PD Sources in 3CFRD
3CFRD
A(fL)>A(fC)>A(fR)
500kHz
fL
fC
fR
2MHz
•timeframe
1 µs
8 MHz
2 MHz
500 kHz
8MHz
3CFRD = 3 Center Frequency Relation Diagram
Annual Convention 2012 – Eilat, Israel
PAGE 52
PD Measurement Cluster 1
•8 MHz
•2.8 MHz
•500 kHz
•500 kHz
•8 MHz
•2.8 MHz
Annual Convention 2012 – Eilat, Israel
•
PAGE 53
PD Measurement Cluster 2
•8 MHz
•2.8 MHz
•500 kHz
•500 kHz
•8 MHz
•2.8 MHz
Annual Convention 2012 – Eilat, Israel
•
PAGE 54
PD Measurement Cluster 3
•8 MHz
•2.8 MHz
•500 kHz
•500 kHz
•8 MHz
•2.8 MHz
Annual Convention 2012 – Eilat, Israel
•
PAGE 55
On-Line Measurements
Advantages:
• Early fault recognition
• tan δ and PD measurement at rated temperature
• tan δ and PD measurement at rated voltage
Drawbacks:
• tan δ Measurement only at 50/60 Hz
• Problems with interference
Annual Convention 2012 – Eilat, Israel
PAGE 56
Tan δ – In-Service Measurements
Existing Solutions for tan δ
Sum of the Currents of 3 Bushings U, V, W
Sum of the currents = 0 ?
Annual Convention 2012 – Eilat, Israel
PAGE 57
Sum is not Constant
Record of One week
Annual Convention 2012 – Eilat, Israel
PAGE 58
3Phase Comparison - Comparison
of the Same Phase
Patric Picher, Claude
Rajotte, Denis Nadeau
“Integration of New
Transformer Monitoring
Technologies into a
Modern IT Infrastructure”,
TechCon Asia-Pazific 2011
Annual Convention 2012 – Eilat, Israel
PAGE 59
Voltage Transformer as Reference
Annual Convention 2012 – Eilat, Israel
PAGE 60
On-Line Measurement
Pilot Project Transformer 405kV / 450MVA
Annual Convention 2012 – Eilat, Israel
PAGE 61
HSP Adaptor at a 400kV Bushing
Annual Convention 2012 – Eilat, Israel
PAGE 62
RFCT at the Neutral
Annual Convention 2012 – Eilat, Israel
PAGE 63
400kV Voltage Transformer
as TanDelta Reference
Annual Convention 2012 – Eilat, Israel
PAGE 64
C-Tandelta Measurement Phase U
Record of Nine Days
•+/- 0.02%
•+/0.7pF
Annual Convention 2012 – Eilat, Israel
PAGE 65
UHF Gating for Interference Suppression
•Corona
•Electr. PD
•Internal
PD
•UHF PD
Annual Convention 2012 – Eilat, Israel
•EM Field
PAGE 66
UHF Sensor in the Transformer Tank
•
UHF-Sensor
•July 15
on-site
in the
factory
Annual Convention 2012 – Eilat, Israel
PAGE 67
Synchronuous elektrical and
UHF Measurement
333 MVA 1-Phase TR
Abnormal DGA
Annual Convention 2012 – Eilat, Israel
PAGE 68
Combination of Methods
IEC
UHF
&
Annual Convention 2012 – Eilat, Israel
PAGE 69
[email protected]
Annual Convention 2012 – Eilat, Israel
Questions and Remarks?