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
1
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
2
Standard for collection, calculation and
reporting – FASIT
FASIT
software
 Introduced in 1995
 Used by all network
companies in Norway
 6 software vendors
 Software quality
assurance (contracts
and acceptance test)
Reporting
schemes
≥ 33 kV
1 - 22 kV
< 1 kV
Basic
requirements
Guidelines
for data
collection
Software
specification
www.fasit.no
Workshop DNV – NTNU 2011-09-27
Risk and vulnerabilities in power systems in light of climate change
FASIT – reliability data classes
• Component
Failure cause
Maintenance
Fault
Planned
disconnection
Forced outage
Interruption
• Voltage level
No
interruption
• End-user
• Network
level/type
CENS
• ENS
• Affected enduser groups
• Responsible
company
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
Generation Transmission Sub-transmission
Import/Export
G
420 kV
300 kV
G
Distribution
Import/Export
132 kV
66 kV
22 kV
11 kV
G
G
Workshop DNV – NTNU 2011-09-27
Risk and vulnerabilities in power systems in light of climate change
230 V
400 V
Number of events 1 – 420 kV
35000
30000
25000
Planned disconnections 33 - 420 kV
20000
Disturbances 33 - 420 kV
Planned disconnections 1 - 22 kV
15000
Temporary failures 1 - 22 kV
Permanent failures 1 - 22 kV
10000
5000
0
FASIT introduced
Lack of detailed data for 2006
About 25000 events per year > 95 % in the distribution network, ~ 50 % disturbances
Workshop DNV – NTNU 2011-09-27
Risk and vulnerabilities in power systems in light of climate change
Energy not supplied 1 – 420 kV
60000
ENS due to planned disconnections 33 - 420 kV (from 2001 only)
50000
Sum
ENS due to disturbances 33 - 420 kV
ENS due to planned disconnections 1 - 22 kV
40000
MWh
per
year
ENS due to disturbances 1 - 22 kV
30000
20000
10000
0
1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010
Sum 2007 should be 14800 MWh
Revenue regulation
CENS
Lack of detailed data for 2006
~ 80 % caused by faults in the distribution network
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
Weather and
unknown/not
clarified fault
causes dominate
Energy not supplied (ENS):
No of disturbances:
Disturbances 1-22 kV divided in triggering fault cause 2007-2010
No triggering fault
Operational stress
cause
Unknown
3%
2%
5%
Construction/
maintentance etc
2%
Human errors
6%
Cause not clarified
28 %
ENS due to disturbances 1-22 kV divided in triggering fault cause 2007-2010
Unknown Operational stress
No triggering fault
3%
4%
cause
Cause not clarified
2%
Construction/
14 %
maintentance etc
3%
Previous faults
0%
Human errors
7%
Technical equipment
22 %
Environment
43 %
Previous faults
0%
Environment
45 %
Technical equipment
11 %
10 %
8%
18 %
5%
34 %
20 %
Lightning
Lightning
Wind
Wind
Snow/ice
Snow/ice
Salt/pollution
15 %
Birds/animals
Other/unknown
18 %
Birds/animals
36 %
Other/unknown
12 %
1%
7%
Salt/pollution
Vegetation
Vegetation
14 %
2%
Workshop DNV – NTNU 2011-09-27
Risk and vulnerabilities in power systems in light of climate change
10
Triggering fault causes 33 – 420 kV
2007 – 2010
Weather , technical
equipment and
human errors
dominate
Energy not supplied (ENS):
No of disturbances:
Distburbances 33-420 kV divided in triggering fault cause 2007-2010
Cause not clarified
10 %
Previous faults
0%
UnknownOperational stress
Construction/
2%
6%
maintentance etc
7%
Human errors
15 %
Technical
equipment
18 %
ENS due to disturbances 33-420 kV divided in triggering fault cause 2007-2010
Cause not clarified Unknown Operational stress
1%
4%
Previous faults 6 %
1%
Construction/
maintentance etc
24 %
Technical
equipment
22 %
Human errors
15 %
Environment
27 %
Environment
42 %
3%
8%
2%
8%
Lightning
12 %
Wind
Snow/ice
3%
50 %
8%
22 %
Lightning
Wind
Snow/ice
Salt/pollution
Salt/pollution
Vegetation
Vegetation
Birds/animals
Other/unknown
16 %
34 %
Birds/animals
3%
Other/unknown
9%
22 %
Workshop DNV – NTNU 2011-09-27
Risk and vulnerabilities in power systems in light of climate change
11
Component faults 1 – 22 kV
2007 – 2010
1-22 kV
4500
3500
No of faults per year 2007-2010
4000
ENS per year år 2007-2010
3000
3500
2500
2000
2500
2000
1500
MWh per year
No of faults per year
3000
1500
1000
1000
500
500
0
0
Overhead line
Underground cable
Breaker, disconnector
Transformer
Other
Not identified
Workshop DNV – NTNU 2011-09-27
Risk and vulnerabilities in power systems in light of climate change
12
Component faults 33 – 420 kV
2007 – 2010
33-420 kV
300
1000
900
No of faults per year 2007-2010
ENS per year 2007-2010
250
800
No of faults per year
600
150
500
400
100
MWh per year
700
200
300
200
50
100
0
Overhead line
Underground cable
Breaker,
disconnector
Transformer
Other
Not identified
Protection
Control equipment
Workshop DNV – NTNU 2011-09-27
Risk and vulnerabilities in power systems in light of climate change
0
13
Fault rate for overhead lines 1 – 22 kV
1989 – 2005
12,0
No. of faults per 100 km
Temporary faults
Permanent faults
10,0
All faults
8,0
6,0
4,0
2,0
0,0
1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006
Year
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
Fault frequency overhead line 1-22 kV
Temporary
Permanent
All faults
Faults per 100 km per year
8
7
6
5
4
3
2
1
0
2007
2008
2009
2010
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
15
Fault rate overhead lines 33 – 420 kV
1989 – 2005
Fault frequency 33 - 420 kV
3,0
No of faults per 100 km per year
2,5
420 kV
220 - 300 kV
2,0
132 kV
33 - 110 kV
1,5
1,0
0,5
0,0
1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
År
Workshop DNV – NTNU 2011-09-27
Risk and vulnerabilities in power systems in light of climate change
16
Fault rate overhead lines 33 – 420 kV
2007 – 2010
Fault frequency overhead lines 33-420 kV
No of faults per 100 km per year
1,8
420
300-220
1,6
132
1,4
110-33
1,2
1
0,8
0,6
0,4
0,2
0
2007
2008
År
2009
2010
420kV – 33 kV: ~ 0,5 - 1 faults per 100 km per year
Workshop DNV – NTNU 2011-09-27
Risk and vulnerabilities in power systems in light of climate change
17
Interruptions 2005 – 2010,
long interruptions > 3 minutes
3,5
4,5
Long interruptions
No of interruptions per
delivery point
2,5
3,5
SAIFI
Hours per year
No of interruptions per year
3
2
1,5
1
Long interruptions
4
3
Annual interruption
duration per delivery
point
2,5
2
SAIDI
1,5
1
0,5
0,5
0
2005
2006
2007
2008
2009
2010
0
2005
2006
2007
2008
2009
2010
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
18
Interruptions 2006 – 2010,
short interruptions ≤ 3 minutes
3,5
3
2,5
SAIFI
2
1,5
1
Short interruptions
2,5
No of interruptions per
delivery point
Minutes per year
No of interruptions per year
3
Short interruptions
2
Annual interruption
duration per delivery
point
1,5
SAIDI
1
0,5
0,5
0
0
2005
2006
2007
2008
2009
2010
2005
2006
2007
2008
2009
2010
About 2,5 short interruptions and 2 minutes per year per delivery point
Workshop DNV – NTNU 2011-09-27
Risk and vulnerabilities in power systems in light of climate change
19
Cost of energy not supplied caused
by different system levels
Cost of short
interruptions
included from
2009
600000
500000
NOK 1000
400000
Distribution
Regional grids
300000
Main grid
200000
Total
100000
0
2007
2008
2009
Distribution counts for 78 %
Workshop DNV – NTNU 2011-09-27
Risk and vulnerabilities in power systems in light of climate change
20
Normal/frequent events vs major events
(large disturbances, HILP)
Causes
Consequences
Minor
Moderate
Natural hazard
Technical/
operational
Human errors
Terror,
sabotage etc.
Power system
failures
Wide-area
interruption/
Blackout
Barriers
Major
Critical
Catastrophic
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
21
Examples of large disturbances
(blackouts), Nordic, Europe, Canada
18000
Sweden 1983
Southern Sweden/ Eastern
Denmark 2003
Western Norway 2004
16000
Helsinki 2003
14000
Southern Sweden 2005
(Gudrun)
Canada 1998
Disconnected load (MW)
12000
France 1999
Europe, UCTE 2006
10000
8000
6000
4000
2000
0
0,1
1
10
100
1000
Hours
Workshop DNV – NTNU 2011-09-27
Risk and vulnerabilities in power systems in light of climate change
22
More examples, Norway, US/Canada...
Historic blackouts: Duration and disconnected load
Canada '98
10.000
Swe/DK '03
W. Norway '04
Gudrun '05
1.000
100
Steigen, Norway '07
Oslo S '07
0,1
1
10
Stipulated average duration (log h)
10
1
1000
100
Critical
infrastructures
Project Vulnerability and security in a changing power system, Nfr/SINTEF Energi, 2009 - 2012
Energiutvalget
august
2011
Workshop DNV25.
– NTNU
2011-09-27
Risk and vulnerabilities in power systems in light of climate change
Disconnected load (log MW)
100.000
US /Canada '03
Fault causes major events - examples
 ”Western Norway”, February
2004, 300 kV
 Breakage of line joint
 Delayed protection response
 Causes:
 Steigen, January 2007, 66 kV
 Breakdown of both overhead
lines
 Causes :
 Storm, icing
 Construction fault
 Construction fault
 Degradation of components
 Degradation (ageing)
 ”Inappropriate” protection
Workshop DNV – NTNU 2011-09-27
Risk and vulnerabilities in power systems in light of climate change
24
Comparison Nordic countries
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
25
Comparison Nordic countries
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
26
Comparison Nordic countries
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
27
Extra slides
Workshop DNV – NTNU 2011-09-27
Risk and vulnerabilities in power systems in light of climate change
28
Software certification: FASIT test
network
E
~ G1
RP4
D
T1
10/66 kV
BL7
BE17
BE1
KL6
BS5
SA6
SA1
BE2
T5
KL5
BE3
BS6
RP3
B
KL1
BE11
SA5
KL2
BE4
LP1
BE5
BE14
RP2
BS1
A
BE1
0
BS3
RP5
BE13
T3
T6
BS4
KA4
KL3 SA4
KA1
T7
SA8
KA3
BE6
BE7
T4
KL4
SA2
BE15
RP6
BS2
KA2
SONE 1
T2
66/22 kV
BE8
BE9
SA7
SONE 2
RP1
SA3
C
BE16
G: Generator
BS: Disconnector
SA: Busbar
KL: Overhead line
BE: Circuit
breaker
KA: Underground
cable
T: Transformer
LP2
RP: Delivery (load) point
BS30
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
Extraordinary Events – Understanding Sequence, Causes, and Remedies
E. Johansson
U.S. and Canada, August 14, 2003
 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)
Time between triggering event
and cascaded tripping ~ 4 h
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
Ref.: Final Report on the 2003 Blackout in the United States and Canada: Causes and Recommendations, U.S.-Canada Power System Outage Task Force
Workshop DNV – NTNU 2011-09-27
Risk and vulnerabilities in power systems in light of climate change
30
U.S. and Canada, August 14, 2003
US / Canada, August 14 2003
Overview of the course of events.1
The map highlights the affected regions.
 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 endusers
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
Operators at First Energy begin to realise that their computer system is out of order and
that the network is in serious jeopardy.
15:42
16:06
Failures
Decreased voltage and increased loading of the underlying 138 kV system, causes 16 lines
to fail in rapid order
Failure
Loss of the 345 kV Sammis-Star line between eastern and northern Ohio due to overload.
Triggers the 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.
 50 million people affected
 61 800 MW lost, 350 000 MWh
lost
System in normal state, within prescribed limits. High, but not abnormally high loads
Aug 14
Cascade
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.
Cascade over. 50 million people deprived of power
16:13
Aug 15
Restoration
Approx 80 % of the energy restored
Ref.: Final Report on the 2003 Blackout in the United States and Canada: Causes
U.S.-Canada Power System Outage Task Force
Augand
22 Recommendations,
Restoration completed
Workshop DNV – NTNU 2011-09-27
Risk and vulnerabilities in power systems in light of climate change
31
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
Ref.: Final Report on the 2003 Blackout in the United States and Canada: Causes and Recommendations, U.S.-Canada Power System Outage Task Force
Workshop DNV – NTNU 2011-09-27
Risk and vulnerabilities in power systems in light of climate change
32