Transcript The Mathematics of the Great U.S. Blackout August 14, 2003 Ralph Fehr, P.E. Engineering Consultant The Mathematics of the Great U.S.

The Mathematics of the Great U.S. Blackout
August 14, 2003
Ralph Fehr, P.E.
Engineering Consultant
The Mathematics of the Great U.S. Blackout
August 14, 2003
Note: The photograph on the preceding slide
has been circulating on the Internet since
shortly after August 14, 2003. It is impressive,
dramatic, and FAKE. But it does attempt to
indicate the huge impact and expanse of the
August 14 event, and most importantly, it
makes for a cool title slide!
Ralph Fehr, P.E.
Engineering Consultant
North American Electric Reliability
Council (NERC)
NERC is a not-for-profit company formed after the
1965 Northeast Blackout to promote the reliability of
the bulk electrical system that serves North America.
North American Electric Reliability
Council (NERC)
NERC is divided into 10 regional reliability councils.
Each council monitors utilities within its geographic area.
North American Electric Reliability
Council (NERC)
3 Interconnections / 10 NERC
Regions
NERC Control Areas
NERC Reliability Coordinators
Footprints of Reliability Coordinators
in Midwest
The August 14, 2003 Blackout was
caused by a cascading series of events.
What started the ball rolling?
A wire attached at two points sags
under its own weight.
The amount of sag is a function of tension.
Tension is a function of wire temperature and weight.
Temperature is a function of several variables – but a
major contributor is electrical loading.
Temperature increases with electrical loading SQUARED.
As the wire temperature INCREASES, the tension DECREASES.
For a level span, the maximum sag D is the y-coordinate at the
midpoint of the line, and is given by:
where S = span length
TH = horizontal component of tension
w = conductor weight per unit length
Effects of Ambient
Conditions on Ratings
Mathematical Analysis of Root Cause
y
Alternate Mathematical Analysis
of Root Cause
y = cosh(x)
Cost maintenance > 0
x
Outage Sequence of Events
Transmission Map Key
ONTARIO
East Lake 5 Trip: 1:31:34 PM
ONTARIO
2
1
Stuart Atlanta Trip: 2:02 PM
ONTARIO
MISO State Estimator and
Reliability Analysis
• MISO state estimator and contingency
analysis ineffective from 12:37 to 16:04
– State estimator not solving due to missing
information on lines out in Cinergy then DPL
– Human error in not resetting SE automatic
trigger
• Using Flowgate Monitoring tool to monitor
conditions on previously identified critical
flowgates
FirstEnergy Computer Failures
• 14:14 Alarm logger fails and operators are not aware
– No further alarms to FE operators
• 14:20 Several remote consoles fail
• 14:41 EMS server hosting alarm processor and other functions
fails to backup
• 14:54 Backup server fails
– EMS continues to function but with very degraded performance
(59 second refresh)
– FE system data passed normally to others: MISO and AEP
– AGC function degraded and strip charts flat-lined
• 15:08 IT warm reboot of EMS appears to work but alarm
process not tested and still in failed condition
• No contingency analysis of events during the day including
loss of East Lake 5 and subsequent line trips
Phone Calls to FirstEnergy
• FE received calls from MISO, AEP, and PJM
indicating problems on the FE system but did not
recognize evolving emergency
– 14:32 AEP calls regarding trip and reclose of Star-S.
Canton
– 15:19 AEP calls again confirming Star-S. Canton trip
and reclose
– 15:35 Calls received about “spikes” seen on system
– 15:36 MISO calls FE regarding contingency overload on
Star-Juniper for loss of Hanna-Juniper
– 15:45 FE tree trimming crew calls in regarding HannaJuniper flashover to a tree
– PJM called MISO at 15:48 and FE at 15:56 regarding
overloads on FE system
The Chamberlin - Harding 345 kV line
sags into a tree at 3:05:41.
Contact with tree causes a ground fault
which results in very high current.
The protective relays on the Chamberlin –
Harding line sense the high current and trip
(de-energize) the line.
A Digital Fault Recorder (DFR) at nearby
Juniper Substation recorded the fault current.
Chamberlin-Harding (3:05:41)
Chamberlin-Harding Indication of Ground Fault Due to
Tree Contact as Measured by DFR at Juniper
y = ex sin x
NOT STABLE
should be
y = e-x sin x
(3:05:41)
Hanna-Juniper
(3:32:03)
Hanna Juniper Confirmed as Tree Contact at
Less than Emergency Ratings of Line
(3:05:41)
Star- S. Canton (3:41:35)
(3:32:03)
Situation after Initial Trips 3:05:41 – 3:41:35
ONTARIO
Canton Central – Tidd
(3:45:41)
Anatomy of a Cascading Outage
20%
20%
Source
20%
20%
20%
Load
Anatomy of a Cascading Outage
0%
25%
Source
25%
25%
25%
Load
Anatomy of a Cascading Outage
0%
0%
Source
33%
33%
33%
Load
Anatomy of a Cascading Outage
0%
0%
Source
0%
50%
50%
Load
Anatomy of a Cascading Outage
0%
0%
Source
0%
0%
100%
Load
138 kV Lines Overload and Cascade Near Akron
Simulated 138 kV Line Loadings
200
Dale-W.Can
138 kV
% of Normal Ratings (Amps)
180
W.Ak-PV
Q22 138 kV
160
Cham-W.Ak
138 kV
140
E.LimaN.Fin 138 kV
120
CantC Xfmr
100
Dale-W.Can
138 kV
W.Ak 138 kV
Bkr Failure
Cham-W.Ak
138 kV
E.Lima-N.Fin
138 kV
Outages
CantC Xfmr
0
W.Ak-PV Q21
138 kV
20
Babb-W.Ak
138 kV
E.LimaN.Lib 138 kV
E.Lima-N.Lib
138 kV
40
Clov-Torrey
138 kV
Babb-W.Ak
138 kV
Star-S.Cant
345 kV
60
Hanna-Jun
345 kV
W.Ak-PV
Q21 138 kV
Hard-Chamb
345 kV
80
Clov-Torrey
138 kV
0
Dale-W.Canton 138 kV
W.Akron 138 kV Breaker
Chamberlin-W.Akron 138 kV
E.Lima-N.Finlay 138 kV
60
16:05:55 EDT
15:51:41 EDT
15:32:03 EDT
Star-S.Canton 15:41:35 EDT
HannaJuniper
20
HardingChamberlin 15:05:41 EDT
40
Sammis-Star
120
Canton Central Transformer
W.Akron-Pleasant Valley 138 kV
Babb-W.Akron 138 kV
E.Lima-New Liberty 138 kV
80
Cloverdale-Torrey 138 kV
100
% of Normal Ratings
138 kV Cascade Contributes Further
to Overload of Sammis-Star
140
Sammis-Star
(4:05:57.5)
Sammis-Star Zone 3 Relay Operates
on Steady State Overload
Operating point
must lie below blue
curve, or line will
trip.
As loading on line
increases, operating
point moves up and
to the left.
Actual Loading on Critical Lines
1600
Harding - Chamberlin
Hanna - Juniper
Star - South Canton
Sammis - Star Line Trip
Sammis - Star
Star - South Canton Line Trip
Hanna - Juniper Line Trip
Flows (MW)
1200
East Lake 5 Trip
800
400
Harding - Chamberlin Line Trip
0
12:00
13:00
14:00
Time - EDT
15:00
16:00
Actual Voltages Leading to Sammis-Star
370
Harding - Chamberlin
345 kV Line Trip
Hanna - Juniper
345 kV Line Trip
Gaps in Data Records
100% Voltage
350
95% Voltage
Voltage (kV)
330
90% Voltage
310
Star
290
270
Hanna
Star - South Canton
345 kV Line Trip
Sammis - Star
345 kV Line Trip
Beaver
Perry
250
15:00
Time - EDT
16:00
Major Path to Cleveland Blocked after Loss
of Sammis-Star 4:05:57.5 PM
Remaining
Paths
345 kV Lines Trip Across Ohio to West
ONTARIO
Generation Trips 4:09:08 – 4:10:27 PM
ONTARIO
345 kV Transmission Cascade Moves North
into Michigan 4:10:36 – 4:10:37 PM
Northern Ohio and Eastern Michigan Served Only
from Ontario after 4:10:37.5 – 4:10:38.6 PM
Power Transfers Shift at 4:10:38.6 PM
Eastern Eastern Michigan (Detroit) Unstable
Voltage and Frequency Collapse and Pole Slipping
Ontario – Michigan Interface Flow and Voltages Beginning 16:10:38
Generator Trips to 16:10:38
Generator Trips – Next 7 Seconds
Overloads on PJM – NY Ties 4:10:39 PM
PJM – NY Separating 4:10:44 PM
Cleveland – Toledo Island 4:10:39 - 4:10:46 PM
Cleveland Blacks Out
Northeast Completes Separation from Eastern
Interconnection 4:10:43 – 4:10:45 PM
Conditions at Niagara Indicate Progressively
Worsening Stability Conditions with Prior Events
Island Breaks Up: 4:10:46 – 4:13 PM
Frequency in Ontario and New York during Breakup
Niagara Generation Stays with Western NY
Generator Trips – After 16:10:44
End of the Cascade
Some Local Load
Interrupted
Areas Affected by the Blackout
Service maintained
in some area
Lessons Learned
Better maintenance practices
Better training for system operators
Better communications between utilities
Can it happen again?
What do you think?
Thank you!
Manhattan skyline with only emergency lighting – August 14, 2003