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Workshop DNV – NTNU 2011-09-27 Risk and vulnerabilities in power systems in light of climate change 1
What do fault statistics tell us regarding causes resulting in power outages?
Gerd H. Kjølle
Professor II Dept. of Electric Power Eng., NTNU Senior Research Scientist, SINTEF Energy Research
Workshop DNV – NTNU 2011-09-27 Risk and vulnerabilities in power systems in light of climate change 2
Content of presentation
FASIT – The Norwegian standard for reliability data collection and reporting
Faults and interruptions (power outages) – definitions Highlights from the fault statistics 1 – 420 kV
Number of events and energy not supplied 1989 – 2010 Fault causes 2007 – 2010 Component faults and fault rates
Interruptions and cost of energy not supplied (CENS) Large disturbances (high impact) Brief comparison Nordic countries
Workshop DNV – NTNU 2011-09-27 Risk and vulnerabilities in power systems in light of climate change
Standard for collection, calculation and reporting – FASIT
Introduced in 1995 Used by all network
companies in Norway 6 software vendors Software quality
assurance (contracts and acceptance test)
FASIT software
Guidelines for data
collection
Reporting schemes
≥ 33 kV 1 - 22 kV
< 1 kV
Software specification
Basic requirements
www.fasit.no
Workshop DNV – NTNU 2011-09-27 Risk and vulnerabilities in power systems in light of climate change
FASIT – reliability data classes
Fault
Failure cause
• Component
• Voltage level
Interruption
No interruption
Forced outage
Maintenance
Planned disconnection
CENS
• ENS • Affected end-user groups • Responsible company
• End-user
• Network level/type
Workshop DNV – NTNU 2011-09-27 Risk and vulnerabilities in power systems in light of climate change
Interruption – definition (EN 50160)
Condition in which the voltage at the supply terminals is lower than 5 % of the reference voltage.
A supply interruption can be classified as prearranged, when network users are informed in advance,
or accidental, caused by permanent or transient faults, mostly
related to external events, equipment failures or interference. An accidental interruption is classified as: a long interruption (longer than 3 min); a short interruption (up to and including 3 min)
Power outage = interruption in this presentation
Workshop DNV – NTNU 2011-09-27 Risk and vulnerabilities in power systems in light of climate change
Fault – definition
Fault is the state of an item characterized by inability to perform a required function (IEC)
Fault causes may be related to construction, production, installation, use or maintenance causing fault on the unit
Fault causes may be classified in triggering, underlying or contributing causes
Faults are divided in Permanent (corrective maintenance/repair) Transient/ temporary (no corrective maintenance/repair,
reconnection of breaker or replacement of fuse)
Workshop DNV – NTNU 2011-09-27 Risk and vulnerabilities in power systems in light of climate change
Power system levels – Norway
420 kV 300 kV
132 kV 66 kV
22 kV 11 kV
230 V 400 V
Import/Export Import/Export
Generation Transmission Sub-transmission Distribution
G
G
G
G
Workshop DNV – NTNU 2011-09-27 Risk and vulnerabilities in power systems in light of climate change
Number of events 1 – 420 kV
About 25000 events per year > 95 % in the distribution network, ~ 50 % disturbances
0
5000
10000
15000
20000
25000
30000
35000
Planned disconnections 33 - 420 kV
Disturbances 33 - 420 kV
Planned disconnections 1 - 22 kV
Temporary failures 1 - 22 kV
Permanent failures 1 - 22 kV
FASIT introduced Lack of detailed data for 2006
Workshop DNV – NTNU 2011-09-27 Risk and vulnerabilities in power systems in light of climate change
Energy not supplied 1 – 420 kV
~ 80 % caused by faults in the distribution network
0
10000
20000
30000
40000
50000
60000
1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010
ENS due to planned disconnections 33 - 420 kV (from 2001 only)
Sum
ENS due to disturbances 33 - 420 kV
ENS due to planned disconnections 1 - 22 kV
ENS due to disturbances 1 - 22 kV
Lack of detailed data for 2006 Sum 2007 should be 14800 MWh
Revenue regulation CENS
MWh per year
Workshop DNV – NTNU 2011-09-27 Risk and vulnerabilities in power systems in light of climate change
Triggering fault causes 1 – 22 kV 2007 - 2010
10
Operational stress3 %
No triggering fault cause2 %
Construction/maintentance etc
2 %Human errors
6 %
Environment43 %
Technical equipment11 %
Previous faults0 %
Cause not clarified28 %
Unknown5 %
Disturbances 1-22 kV divided in triggering fault cause 2007-2010
No of disturbances: Energy not supplied (ENS):
Operational stress4 % No triggering fault
cause2 % Construction/
maintentance etc3 %
Human errors7 %
Environment45 %
Technical equipment22 %
Previous faults0 %
Cause not clarified14 %
Unknown3 %
ENS due to disturbances 1-22 kV divided in triggering fault cause 2007-2010
34 %
12 %
7 %1 %
18 %
20 %
8 %
Lightning
Wind
Snow/ice
Salt/pollution
Vegetation
Birds/animals
Other/unknown
18 %
15 %
14 %2 %
36 %
5 %
10 %
Lightning
Wind
Snow/ice
Salt/pollution
Vegetation
Birds/animals
Other/unknown
Weather and unknown/not clarified fault causes dominate
Workshop DNV – NTNU 2011-09-27 Risk and vulnerabilities in power systems in light of climate change
Triggering fault causes 33 – 420 kV 2007 – 2010
11
No of disturbances: Energy not supplied (ENS):
Operational stress6 %
Construction/maintentance etc
7 %
Human errors15 %
Environment42 %
Technical equipment
18 %
Previous faults0 %
Cause not clarified10 %
Unknown2 %
Distburbances 33-420 kV divided in triggering fault cause 2007-2010Operational stress
4 %
Construction/maintentance etc
24 %
Human errors15 %
Environment27 %
Technical equipment
22 %
Previous faults1 %
Cause not clarified6 %
Unknown1 %
ENS due to disturbances 33-420 kV divided in triggering fault cause 2007-2010
50 %
16 %
8 %
3 %
12 %
3 %8 %
Lightning
Wind
Snow/ice
Salt/pollution
Vegetation
Birds/animals
Other/unknown
34 %
22 %9 %
3 %
22 %
2 %8 %
Lightning
Wind
Snow/ice
Salt/pollution
Vegetation
Birds/animals
Other/unknown
Weather , technical equipment and human errors dominate
Workshop DNV – NTNU 2011-09-27 Risk and vulnerabilities in power systems in light of climate change
Component faults 1 – 22 kV 2007 – 2010
12
0
500
1000
1500
2000
2500
3000
3500
0
500
1000
1500
2000
2500
3000
3500
4000
4500
Overhead line Underground cable Breaker, disconnector Transformer Other Not identified
No
of fa
ults
per
year
MW
h pe
r yea
r
1-22 kV
No of faults per year 2007-2010
ENS per year år 2007-2010
Workshop DNV – NTNU 2011-09-27 Risk and vulnerabilities in power systems in light of climate change
Component faults 33 – 420 kV 2007 – 2010
13
0
100
200
300
400
500
600
700
800
900
1000
0
50
100
150
200
250
300
Overhead line Underground cable Breaker, disconnector
Transformer Other Not identified Protection Control equipment
MW
h pe
r yea
r
No
of fa
ults
per
year
33-420 kV
No of faults per year 2007-2010
ENS per year 2007-2010
Workshop DNV – NTNU 2011-09-27 Risk and vulnerabilities in power systems in light of climate change
Fault rate for overhead lines 1 – 22 kV 1989 – 2005
0,0
2,0
4,0
6,0
8,0
10,0
12,0
1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006
Year
No.
of f
aults
per
100
km
Temporary faultsPermanent faultsAll faults
FASIT introduced
New version of FASIT
Workshop DNV – NTNU 2011-09-27 Risk and vulnerabilities in power systems in light of climate change
Fault rate overhead lines 1 – 22 kV 2007 – 2010
15
0
1
2
3
4
5
6
7
8
2007 2008 2009 2010
Faul
ts p
er 1
00 km
per
yea
r
Fault frequency overhead line 1-22 kV
Temporary Permanent All faults
1 – 22kV: 6 – 7 faults per 100 km per year
Workshop DNV – NTNU 2011-09-27 Risk and vulnerabilities in power systems in light of climate change
Fault rate overhead lines 33 – 420 kV 1989 – 2005
16
0,0
0,5
1,0
1,5
2,0
2,5
3,0
1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
No o
f fau
lts p
er 1
00 k
m p
er y
ear
År
Fault frequency 33 - 420 kV
420 kV
220 - 300 kV
132 kV
33 - 110 kV
Workshop DNV – NTNU 2011-09-27 Risk and vulnerabilities in power systems in light of climate change
Fault rate overhead lines 33 – 420 kV 2007 – 2010
17
420kV – 33 kV: ~ 0,5 - 1 faults per 100 km per year
0
0,2
0,4
0,6
0,8
1
1,2
1,4
1,6
1,8
2007 2008 2009 2010
No
of fa
ults
per
100
km p
er ye
ar
År
Fault frequency overhead lines 33-420 kV420
300-220
132
110-33
Workshop DNV – NTNU 2011-09-27 Risk and vulnerabilities in power systems in light of climate change
Interruptions 2005 – 2010, long interruptions > 3 minutes
18
0
0,5
1
1,5
2
2,5
3
3,5
2005 2006 2007 2008 2009 2010
No
of in
terr
uptio
ns p
er y
ear
Long interruptions
No of interruptions per delivery point
SAIFI
0
0,5
1
1,5
2
2,5
3
3,5
4
4,5
2005 2006 2007 2008 2009 2010
Hour
s per
year
Long interruptions
Annual interruption duration per delivery point
SAIDI
About 3 long interruptions and 3 – 4 hours per year per delivery point
Workshop DNV – NTNU 2011-09-27 Risk and vulnerabilities in power systems in light of climate change
Interruptions 2006 – 2010, short interruptions ≤ 3 minutes
19
About 2,5 short interruptions and 2 minutes per year per delivery point
0
0,5
1
1,5
2
2,5
3
3,5
2005 2006 2007 2008 2009 2010
No
of in
terr
uptio
ns p
er y
ear
Short interruptions
No of interruptions per delivery point
SAIFI
0
0,5
1
1,5
2
2,5
3
2005 2006 2007 2008 2009 2010
Min
utes
per
yea
r
Short interruptions
Annual interruption duration per delivery point
SAIDI
Workshop DNV – NTNU 2011-09-27 Risk and vulnerabilities in power systems in light of climate change
Cost of energy not supplied caused by different system levels
20
0
100000
200000
300000
400000
500000
600000
2007 2008 2009
NO
K 10
00 Distribution
Regional grids
Main grid
Total
Cost of short interruptions included from 2009
Distribution counts for 78 %
Workshop DNV – NTNU 2011-09-27 Risk and vulnerabilities in power systems in light of climate change 21
Normal/frequent events vs major events (large disturbances, HILP)
Power system failures
Causes Consequences Natural hazard Technical/ operational Human errors Terror, sabotage etc.
Barriers
Minor Moderate
Major Critical Catastrophic
Wide-area interruption/
Blackout
Fault statistics mainly give information about normal/frequent events
Workshop DNV – NTNU 2011-09-27 Risk and vulnerabilities in power systems in light of climate change 22
Examples of large disturbances (blackouts), Nordic, Europe, Canada
0
2000
4000
6000
8000
10000
12000
14000
16000
18000
0,1 1 10 100 1000Hours
Dis
conn
ecte
d lo
ad (M
W)
Sweden 1983
Southern Sweden/ EasternDenmark 2003Western Norway 2004
Helsinki 2003
Southern Sweden 2005(Gudrun)Canada 1998
France 1999
Europe, UCTE 2006
Workshop DNV – NTNU 2011-09-27 Risk and vulnerabilities in power systems in light of climate change
More examples, Norway, US/Canada...
Historic blackouts: Duration and disconnected load
1
10
100
1.000
10.000
100.000
0,1 1 10 100 1000
Stipulated average duration (log h)
Dis
conn
ecte
d lo
ad (l
og M
W)
Gudrun '05
Steigen, Norway '07
Oslo S '07
US /Canada '03
W. Norway '04
Swe/DK '03
Canada '98
Project Vulnerability and security in a changing power system, Nfr/SINTEF Energi, 2009 - 2012
Critical infrastructures
Energiutvalget 25. august 2011
Workshop DNV – NTNU 2011-09-27 Risk and vulnerabilities in power systems in light of climate change 24
Fault causes major events - examples
”Western Norway”, February 2004, 300 kV
Breakage of line joint Delayed protection response
Causes: Construction fault Degradation of components ”Inappropriate” protection
Steigen, January 2007, 66 kV Breakdown of both overhead
lines Causes :
Storm, icing Construction fault Degradation (ageing)
Workshop DNV – NTNU 2011-09-27 Risk and vulnerabilities in power systems in light of climate change
Comparison Nordic countries
25
ENTSO-E Nordic Grid disturbance and fault statistics 2008
Workshop DNV – NTNU 2011-09-27 Risk and vulnerabilities in power systems in light of climate change
Comparison Nordic countries
26
ENTSO-E Nordic Grid disturbance and fault statistics 2008
Workshop DNV – NTNU 2011-09-27 Risk and vulnerabilities in power systems in light of climate change
Comparison Nordic countries
27
ENTSO-E Nordic Grid disturbance and fault statistics 2008
Workshop DNV – NTNU 2011-09-27 Risk and vulnerabilities in power systems in light of climate change 28
Extra slides
Workshop DNV – NTNU 2011-09-27 Risk and vulnerabilities in power systems in light of climate change
Software certification: FASIT test network
LP2
D ~ G1
10/66 kV
BE1
RP1
BE2 BE3
SA1
KL1 KL2
BE4 BE5
BE7
66/22 kV T2
A
C
BE8
KL3
BE6
SA2
LP1
B
BS1
SA4
BE10 T3
RP2
BE9
KL4
BS2
SA5 BE11 T4
RP3
KL5 SA6
BL7 T5
RP4
KA2
SA7
BE13 T6
RP5
KA3 SA8 BE14 T7
RP6
SA3
KA1
SONE 2
BE17
BE15
BS5
BS6
KL6
BS3 KA4 BS4
T1
BE16
E
SONE 1
BS30
G: Generator
SA: Busbar
BE: Circuit breaker
BS: Disconnector
KL: Overhead line
KA: Underground cable
T: Transformer
RP: Delivery (load) point
LP: Delivery point
A, B, C, D: Network companies
Workshop DNV – NTNU 2011-09-27 Risk and vulnerabilities in power systems in light of climate change 30 30
U.S. and Canada, August 14, 2003
Ref.: Final Report on the 2003 Blackout in the United States and Canada: Causes and Recommendations, U.S.-Canada Power System Outage Task Force
Simplified description of the event
1. 12.15-14.54: Malfunctioning software systems limiting the operators situation awareness and control (State Estimator, SCADA alarm and logging, EMS terminals and server)
2. 13.31: Trip of important generation increases loading on lines
3. 14.02-16.05: Tripping of highly loaded lines, with premature tripping of many lines due to inadequate vegetation management
4. 16.06-16.11: This eventually caused instability, triggering cascaded tripping, separating the Eastern Interconnection into two asynchronous areas
5. 16.11-16.13: Large differences between load and generation, led to instability and blackout of the island consisting of parts of Northeastern U.S and Ontario
Time between triggering event and cascaded tripping ~ 4 h
Extraordinary Events – Understanding Sequence, Causes, and Remedies E. Johansson
Workshop DNV – NTNU 2011-09-27 Risk and vulnerabilities in power systems in light of climate change 31 31
Ref.: Final Report on the 2003 Blackout in the United States and Canada: Causes and Recommendations, U.S.-Canada Power System Outage Task Force
U.S. and Canada, August 14, 2003
Threats Malfunction of computer
systems for system operation Overgrown vegetation Inadequate system
understanding, operator training and clarification of responsibility
Inadequate protection system/ scheme
Final consequences for end-users 50 million people affected 61 800 MW lost, 350 000 MWh
lost
US / Canada, August 14 2003 Overview of the course of events.1
The map highlights the affected regions.
Aug 14 System in normal state, within prescribed limits. High, but not abnormally high loads
12:15 Failure (info)
Erroneous input data put the Midwest Independent System Operator’s state estimator and real time contingency analysis tool out of service
13:31 Failure Generator at Eastlake power plant trips – loss of important source of reactive power
14:02 Failure 345 kV line trips due to tree contact caused by high temperature and line-sagging
14:14 Failure (info)
Control room operators at First Energy looses the alarm function (with no one in the control room realising this)
15:05 – 15:41 Failures Three 345 kV lines into the Cleveland-Akron area trips due to tree contact. Loads on other
lines increase
15:42 Operators at First Energy begin to realise that their computer system is out of order and that the network is in serious jeopardy.
Failures Decreased voltage and increased loading of the underlying 138 kV system, causes 16 lines to fail in rapid order
16:06 Failure Loss of the 345 kV Sammis-Star line between eastern and northern Ohio due to overload. Triggers the cascade
Cascade
Uncontrolled power surges and overload causes relays to trip lines and generators. Northeastern US and Ontario form a large electrical island, which quickly becomes unstable due to lack of generation capacity to meet the demand. Further tripping of lines and generators breaks the area into several electric islands, and most of these black out completely. Some smaller islands with sufficient generation manage to stabilize.
16:13 Cascade over. 50 million people deprived of power
Aug 15 Restoration Approx 80 % of the energy restored
Aug 22 Restoration completed
Workshop DNV – NTNU 2011-09-27 Risk and vulnerabilities in power systems in light of climate change 32 32
Ref.: Final Report on the 2003 Blackout in the United States and Canada: Causes and Recommendations, U.S.-Canada Power System Outage Task Force
U.S. and Canada, August 14, 2003
Vulnerabilities Lack of sufficient tools, competence and standards, leading to: Inadequate situational awareness Insufficient diagnostic support from the interconnected grid’s reliability
coordinator (MISO) Barriers to prevent component failure
Vegetation management Monitoring of lines and operation to prevent overload.
Barriers to prevent power system failure Situation awareness and response of TSOs, operator training Computer tools for monitoring, and back-up systems for these Reliability standards and clear areas of responsibility; ensure operation
within secure limits Information sharing between TSOs