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