The Mathematics of the Great U.S. Blackout August 14, 2003
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Transcript of The Mathematics of the Great U.S. Blackout August 14, 2003
The Mathematics of the Great U.S. BlackoutAugust 14, 2003
Ralph Fehr, P.E.Engineering Consultant
The Mathematics of the Great U.S. BlackoutAugust 14, 2003
Ralph Fehr, P.E.Engineering Consultant
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!
North American Electric Reliability North American Electric Reliability Council (NERC)Council (NERC)
NERC is a not-for-profit company formed after NERC is a not-for-profit company formed after the 1965 Northeast Blackout to promote the the 1965 Northeast Blackout to promote the reliability of the bulk electrical system that reliability of the bulk electrical system that serves North America.serves North America.
North American Electric Reliability North American Electric Reliability Council (NERC)Council (NERC)
NERC is divided into 10 regional reliability councils.NERC is divided into 10 regional reliability councils.
Each council monitors utilities within its geographic Each council monitors utilities within its geographic area.area.
North American Electric Reliability North American Electric Reliability Council (NERC)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 sagsunder its own weight.
The amount of sag is a function of tension.
where S = span lengthTH = horizontal component of tensionw = conductor weight per unit length
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:
Effects of Ambient Conditions on Ratings
x
y
y = cosh(x)
Mathematical Analysis of Root Cause
Alternate Mathematical Analysis of Root Cause
Cost maintenance > 0
Outage Sequence of EventsTransmission Map Key
O N T A R I O
Transmission Lines
765 kV
500 kV
345 kV
230 kV
Transmission Lines
765 kV
500 kV
345 kV
230 kV
East Lake 5 Trip: 1:31:34 PMONTARIO
2
1
ONTARIO
Stuart Atlanta Trip: 2:02 PM
ONTARIO
MISO State Estimator andReliability 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
Hanna-Juniper 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 xNOT STABLEshould bey = e-x sin x
(3:05:41) Hanna-Juniper(3:32:03)
Hanna Juniper Confirmed as Tree Contact atLess than Emergency Ratings of Line
(3:05:41)(3:32:03)
Star- S. Canton (3:41:35)
Situation after Initial Trips 3:05:41 – 3:41:35
ONTARIO
Canton Central – Tidd(3:45:41)
Anatomy of a Cascading Outage
Source Load
20%
20%
20%
20%
20%
Anatomy of a Cascading Outage
Source Load
0%
25%
25%
25%
25%
Anatomy of a Cascading Outage
Source Load
0%
0%
33%
33%
33%
Anatomy of a Cascading Outage
Source Load
0%
0%
0%
50%
50%
Anatomy of a Cascading Outage
Source Load
0%
0%
0%
0%
100%
138 kV Lines Overload and Cascade Near Akron
Simulated 138 kV Line Loadings
0
20
40
60
80
100
120
140
160
180
200
Outages
% o
f N
orm
al
Rati
ng
s (
Am
ps)
Dale-W.Can138 kV
W.Ak-PVQ22 138 kV
Cham-W.Ak138 kV
E.Lima-N.Fin 138 kV
CantC Xfmr
W.Ak-PVQ21 138 kV
Babb-W.Ak138 kV
E.Lima-N.Lib 138 kV
Clov-Torrey138 kV
Da
le-W
.Ca
n
13
8 k
V
W.A
k 1
38
kV
Bk
r Fa
ilure
E.L
ima
-N.F
in
13
8 k
V
Ca
ntC
Xfm
r
W.A
k-P
V Q
21
13
8 k
V
Ba
bb
-W.A
k
13
8 k
V
E.L
ima
-N.L
ib
13
8 k
V
Clo
v-T
orre
y
13
8 k
V
Sta
r-S.C
an
t
34
5 k
V
Ha
nn
a-J
un
34
5 k
V
Ha
rd-C
ha
mb
34
5 k
V
Ch
am
-W.A
k
13
8 k
V
15
:05
:41
ED
T
15
:32
:03
ED
T
15
:41
:35
ED
T
15
:51
:41
ED
T
16
:05
:55
ED
T
0
20
40
60
80
100
120
140
% o
f N
orm
al R
atin
gs
Can
ton
Cen
tral Tran
sform
er
Bab
b-W
.Akro
n 138 kV
Hard
ing
-C
ham
berlin
Han
na-
Jun
iper
Star-S
.Can
ton
Clo
verdale-T
orrey 138 kV
E.L
ima-N
ew L
iberty 138 kV
W.A
kron
-Pleasan
t Valley 138 kV
E.L
ima-N
.Fin
lay 138 kV
Ch
amb
erlin-W
.Akro
n 138 kV
W.A
kron
138 kV B
reaker
Dale-W
.Can
ton
138 kV
Sammis-Star
138 kV Cascade Contributes Furtherto Overload of Sammis-Star
Sammis-Star(4:05:57.5)
Sammis-Star Zone 3 Relay Operateson Steady State Overload
Operating pointmust lie below bluecurve, or line willtrip.
As loading on lineincreases, operatingpoint moves up andto the left.
Actual Loading on Critical Lines
0
400
800
1200
1600
12:00 13:00 14:00 15:00 16:00
Time - EDT
Flo
ws
(M
W)
Harding - Chamberlin
Hanna - JuniperStar - South Canton
Sammis - Star
East Lake 5 Trip
Harding - Chamberlin Line Trip
Hanna - Juniper Line Trip
Sammis - Star Line Trip
Star - South Canton Line Trip
Actual Voltages Leading to Sammis-Star
250
270
290
310
330
350
370
15:00 16:00Time - EDT
Vo
ltag
e (
kV
)
Star
Hanna
Beaver
Perry
100% Voltage
95% Voltage
90% Voltage
Sammis - Star
345 kV Line Trip
Star - South Canton345 kV Line Trip
Hanna - Juniper345 kV Line Trip
Harding - Chamberlin345 kV Line Trip
Gaps in Data Records
Major Path to Cleveland Blocked after Loss of Sammis-Star 4:05:57.5 PM
RemainingPaths
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) UnstableVoltage 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 PMCleveland 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 BreakupNiagara Generation Stays with Western NY
Generator Trips – After 16:10:44
Areas Affected by the BlackoutService maintained
in some area
Some Local Load Interrupted
End of the Cascade
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