The Texas Blackout of February 2021 - Thomas Overbye O'Donnell Foundation Chair III Electrical and Computer Engineering IEEE PES ...
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The Texas Blackout of
February 2021
Thomas Overbye
O’Donnell Foundation Chair III
Electrical and Computer Engineering
overbye@tamu.edu
IEEE PES Chicago Chapter
May 26, 2021
Our Energy Future Could be Quite Bright!
• My professional goal is to help in the development of
a sustainable and resilient electric infrastructure for
the entire world.
• Electric grids are in a time of rapid transition, with
lots of positive developments.
• I think our electric energy future could be quite bright!
But there are lots of challenges with this transition,
including maintaining human situational awareness,
particularly during times of stress.
• This presentation covers the Texas 2021 blackout
and related resiliency issues
22
North America Grid Interconnections
Lubbock Power and
Light is joining
ERCOT by 6/1/21
3
US Generation by Fuel Type
Oval size is proportional to the substation generation capacity, and color indicates primary fuel type (red
nuclear, black coal, brown natural gas, blue hydro, green wind, yellow solar). Image shows public data
from EIA Form 860; image created using PowerWorld Simulator.
4
JM Shaf er Gener at ing St at ion Nodaway Tilt on Geor get own
Calif or nia Ridge Wind Ener gy LLC
Spindle Hil Ener gy Cent er
Rocky M ount ain Ener gy Cent er Henr y Count y
Beat r ic e Clint on Power St at ion Ric hm ond
M anchief Elect r ic Gener at ing St at ion
For t Lupt on Cooper Nuclear St at ion Yankee St r
Pr oj ect
Hilt opper Wind Pr oj ect Goose Cr eek Ener gy Cent er
Cayuga Madison
Huntington Fr ank Knut son
Ver m ilon Ener gy Facilit y
I nt er st at e Radf or ds Run Wind Far m Har ding St r eet M iddlet own Ener gy
Plains End
Lake Road ( M O) Ham ilt on ( OH) Wo o d sd a l e
Cherokee Chilic ot he Dallman Ar cher Daniels M idland Decat ur
Osbor n Wind Ener gy
Cabin Cr eek
Wabash Valley Power I GCC Dic ks Cr eek
Als ey
Blue Spr uce Ener gy Cent er
Sugar Cr eek Power Eagle Valley ( I N)
Thomas Hill Lawr encebur g Power , LLC
Cedar Point Wind Lim on Wind I Clif t on Miami Fort
Hunter
Iatan Peno Cr eek
Kincaid Gener at ion LLC
Ener gy Shelby Count y
Bur lingt on ( CO) Audr ain Gener at ing St at ion Wor t hingt on Gener at ion LLC
Cloud Count y Wind Far m
Lim on Wind I I Lim on I I I Wind LLC
Holland Ener gy Facilit y
Solom on For ks Wind Pr oj ect , LLC
Hawthorn Merom W H Zim
Clifty Creek
2019 US Generation by Capacity
M ount Elber t
Je ffre y E n e rg y Ce n te r Quindar o
East Bend
Sioux Edwardsport
Rush Cr eek Wind
M ar kland
Near m an Cr eek
Newton Lawr ence Count y St at ion
Buckeye Wind Ener gy Cent er Blue Valley
M ar t in Dr ake
Nor t heast ( M O)
Golden West Power Par t ner s LLC Wheat land Gener at ing Facilit y
Lawr ence Ener gy Cent er
Kaw
Kinm undy
Ray D Nixon
Gr eenwood ( M O)
Ve n i ce Ghent
Raccoon Cr eek Ener gy Cent er
AES Petersburg Trimble County
M or r ow Point Blue M esa
Fr ont Range Power Plant
Cedar Bluf f Wind, LLC
Ralph Gr een Callaway R Gallagher
West Gar dner
Fount ain Valley Power Facilit y
Dogwood Ener gy Facilit y
Holden
Labadie
G ibson
Sout h Har per
Diam ond Vis t a Wind Pr oj ect , LLC Fair gr ounds
Pr air ie St at e Gener at ing St at ion
Pueblo Air por t Gener at ing St at ion
Em por ia Ener gy Cent er
Osawat om ie
Meramec Cane Run
Ohio Falls
M cPher son 3
M cPher son 2 Bluegr ass Gener at ing St at ion
Paddys Run
Har r y Tr um an
Comanche ( CO) Com anche Solar
JK
Rockport
Kennet h C Colem an
Gar den Cit y Waver ly Wind Far m LLC
Wolf Cr eek Gener at ing St at ion
La Cygne Osage Dam
Pinckneyvile
Warrick
Hut chinson Ener gy Cent er Baldwin Ener gy Com plex
and Fuel Type (Zoomed on Texas
Spear vile
Holc om b Mill Creek ( KY) E W Brown
Spear vile 3 LLC Rush I sland Kent ucky M ils
West er n Plains Wind Far m
A B Brown
F B Culley
Pr air ie Queen Wind Far m
Gor don Evans Ener gy Cent er Ma ri o n
I r onwood Wind
For t Dodge Ninnescah Wind Ener gy, LLC Elm er Sm it h
Rober t A Reid
Buf f alo Dunes Wind Pr oj ect
Chanut e 2 Gr and Tower Ener gy Cent er LLC
Elk River Wind
Ensign Wind LLC
Kingm an Wind M EPI GT Facilit y R D Gre e n D B Wi l so n
Gl e n Ca n y o n Da m CP Bloom Wind LLC
Pr at t Wind, LLC
Rubar t Shoot ing St ar
Caney River Wind Pr oj ect Asbur y Taum Sauk
San Juan Flat Ridge 2 Wind Ener gy LLC M cCar t ney
Cooper Laur el Dam
Cim ar r on Bend Wind Pr oj ect I , LLC
John Twit t y Ener gy Cent er
Jo p p a S te a m
Shawnee
Bar kley
Paradise
Wolf Cr eek
Kay Wind, LLC River t on
Em pir e Ener gy Cent er
Kent ucky Dam
St at e Line Com bined Cycle
Jam es River Power St at ion
Bluf f view Essex Sikest on Power St at ion
M ar shall Ener gy Facilit y
Four Corners Gr ant Wind, LLC
Fr ont ier Windpower
Ponca Cit y
Osage Wind, LLC
KODE Novus I Thunder Ranch Wind Pr oj ect Northeastern St Fr ancis Ener gy Facilit y
Goodwell Wind Pr oj ect LLC Chis holm View Wind Pr oj ect Pensacola
Cor dell Hull
Balko Wind LLC
Bluest em Table Rock
New Madrid
M oor eland
Chouteau Cumberland (TN)
Old Hic kor y
Gallatin (TN) Kingston
Sooner
Beaver Dam
Salina
Bull Shoals
Cent er Hil
Gleason Gener at ing Facilit y
Tuls a F l i n t Cre e k
Ar m adilo Flat s Wind Pr oj ect , LLC
Palo Dur o Wind Nor f or k M
Wat t s Bar Hydr o
Seiling Wind I M ar kham
Red Dir t Wind Pr oj ect
Cr ossr oads Wind Far m
GREC
Har r y D M at t is on Gas Plant
Gr eat West er n Wind Ener
Per sigy,
m m LLC
on Cr eek Wind Far m 1, LLC
Dell Power St at ion
Seiling Wind I I
Ri v e rsi d e (OK) Johnsonville Wa tts Ba r Nu cl e a r P l a n t
Jonesbor o Cit y Wat er & Light Plant
Onet a Ener gy Cent er
M am m ot h Plains
Black Hawk St at ion
Kingf is her Wind LLC
Taloga Wind LLC Spr ing Cr eek Ener gy Cent er Lagoon Creek
I ndependence St eam Elect r ic St at ion
Redbud Power Plant
Escalant e
Plum Point Ener gy St at ion
M iam i Wind Ener gy Cent er
Canadian Hils Wind
Harrington
Pat t er n Panhandle Wind 2 LLC
Gr een Count r y Ener gy LLC
Ozar k
Sequoyah
Muskogee
Spinning Spur Wind I I I Br ownsvile Peaking Power
M uskogee M il
Cholla Reeves
Pat t er n Panhandle Wind LLC
Mu sta n g
Elk Cit y LLC
Ar kansas Nuclear One
Fr ont ier Thom as Fit zhugh
Ra cco o n Mo u n ta i n
Tinker Hor seshoe Lake
Pic kwic k Landing Dam
Canadian Br eaks, LLC Wheeler Dam
Colbeck's Cor ner , LLC Webber s Falls Rober t S Ker r Car l Bailey
Rio Br avo
Chic kam auga
Gr andview Wind Far m , LLC Weleet ka
Ni ch o l s
Coronado
S o u th we ste rn
Euf aula Dam
Dar danelle
Allen Browns Ferry Nic kaj ack
Thom as A Sm it h Ener gy Facilit y
M cClain Ener gy Facilit y C
Anadar ko Plant River Valley
Br oadview Ener gy JN, LLC
Wi l so n Da m
TVA Sout haven Com bined Cycle
TX Her ef or d Wind
M ar iah del Nor t e M agnolia Power Plant
Har r y L. Oswald
El Cabo Wind
Seminole
TX Jum bo Road Wind
Gr ady Wind Ener gy Cent er , LLC
New M exic o Wind Ener gy Cent er
Ast r a Wind Far m
Decat ur Ener gy Cent er Rocky M ount ain Hydr oelect r ic Plant
Co l b e rt
Allat oona
Springerville
Bow en
Blakely M ount ain Gunt er svile
Bet hel Wind Far m LLC
Br is coe Wind Far m M or gan Ener gy Cent er
Kiam ic hi Ener gy Facilit y
Rush Spr ings Wind Lake Cat her ine Ma g n e t Co v e
St ut t gar t Solar
Weis s Dam
White Bluff
Com anche ( OK)
Longhor n Wind
Ocotillo Sout h Plains I I
Or igin Wind
Gadsden
Bat esvile Gener at ion Facilit y
Ja
M or m on Flat
Hor se M esa
Tolk Pla nt X Blue Sum m it I I I Wind Elect r a Wind Far m
Lewis Sm it h Dam
Sewell Cr eek Ener gy
Degr ay
Old Set t ler Wind Cr ossr oads Ener gy Cent er
Hot Spr ing Gener at ing Facilit y
Hale Com m unit y Wind Far m
Sout h Plains Wind Phase I
Locket t Windf ar m Hu g o Pine Bluf f Ener gy Cent er
Pine Bluf f M il
Roosevelt Count y
Oklaunion Dam 2
Denis on
Santan Elk Station Foar d Cit y Wind
Par is Ener gy Cent er
Calhoun Ener gy Cent er
Wansley Unit 9 Wansley
Ant elope St at ion
Wake Wind Ener gy Cent er
Wolf Ridge Wind
Caledonia James H Miller Jr
Ya
John W Tur k Jr Power Plant
Lor enzo Wind
Shannon Wind Panda Sher m an Power St at ion
Ashdown
M cClelan ( AR)
Chat t ahoochee Ener gy Facilit y
Lam ar Power Pr oj ect
Red Hils Gener at ing Facilit yQuant um Choct aw Power LLC
Jones
Hawk Road Facilit y
Windt hor st - 2
Ty Cooke
Tr init y Hils
Fult on ( AR)
Colum bus M S
E C Gaston Har r is Dam
Wansley Com bined Cycle
Sundance Jack County Dent on Ener gy Cent er Ge ra l d An d ru s AM EA Peaking
Wilow Spr ings Wind Far m Choct aw Count y
Hor se Cr eek Wind Far m Spencer
Coolidge Gener at ion St at ion
Senat e Wind LLC
Ray Olinger
Union Power Station Tenaska Geor gia Gener at ion Facilit y
M ust ang St at ion Unit 4
Tahoka Wind
Br azos Wind Far m
Power lane Plant Welsh
Hilabee Ener gy Cent er
Graham
Lay Dam
Keechi Wind
Der m ot t Wind
L a k e Hu b b a rd
Fluvanna
Wis e Count y Power LLC
Wilkes Kem per Count y
Bull Cr eek Wind Atta l a M it chell Dam
Bar t let t s Fer r y
Saguar o M ust ang St at ion
Handley
Hobbs Gener at ing St at ion
St ephens Ranch Wind Ener gy LLC Tenaska Lindsay Hil Gener at ing St at ion
Nor t h Loop
EG178 Facilit y
Hackber r y Wind Far m
Lieber m an
Ouachita Jor dan Dam
M ar t in Dam
Red Hor se 2
Pyr on Wind Far m LLC Hybr id
Lam esa Solar
Mo u n ta i n Cre e k Gre e n e Co u n ty
Dem oss Pet r ie Cunningham
For ney Ener gy Cent er
Ratcliffe Talb
Tenaska Cent r al Alabam a Gener at ing St n Walt er Bouldin Dam
M esquit e Cr eek Wind
Luna Ener gy Facilit y
M addox
M esquit e Wind Power LLC
R W Miller East m an Cogener at ion Facilit y
Pirkey Per r yvile Power St at ion
H Allen Fr anklin Com bined Cycle
I nadale Wind Far m LLC Hybr id J Lam ar St all Unit
Thur low Dam
Pyr am id
Lapet us Roscoe Wind Far m LLC
H Wils on Sundt Gener at ing St at ion
Wo l f Ho l l o w IIDeCor dova St eam Elect r ic St at ion
NRG St er lingt on Power
Post Oak Wind LLC
Baxt er Wils on Hinds Ener gy Facilit y
Ap a ch e S ta ti o n Af t on Gener at ing St at ion
C R Wing Cogen Plant
Johnson Count y Har r is on Count y Power Pr oj ect Ar senal Hil
Buf f alo Gap 2 Wind Far m
Kn o x L e e
Newman
Jones Bluf f
E B Har r is Elect r ic Gener at ing Plant
M or gan Cr eek
M idlot hian Ener gy Facilit y M iler s Fer r y
Ect or Count y Ener gy Cent er
Tr inidad ( TX) M ansf ield M il
Sweet wat er Wind 4 LLC
Martin Lake
Ennis Power Com pany LLC
Not r ees Windpower Hybr id
Wolf Hollow I LP Sylvar ena
M ont ana Power St at ion Comanche Peak Grand Gulf Walt er F Geor ge
Pant her Cr eek Wind Far m Thr ee Hor se Hollow Wind Ener gy Cent er
Rio Gr ande
Quail Run Ener gy Cent er Fr eest one Ener gy Cent er
Dolet Hills
Phoebe Solar
Char les R Lowm an
Valencia Goat Wind LP
Copper
Odessa- Ect or Power Plant S try k e r Cre e k
SR
Capr ic or n Ridge Wind LLC Logans Gap Wind LLC
Silver Cr eek Mo se l l e
Bosque Count y Peaking
Bear kat Tenaska Gat eway Gener at ing St at ion
Rat t lesnake Den M cI nt osh ( AL)
McWi l l i a m s
Per m ian Basin Flat Top Wind I
Br am e Ener gy Cent er
Jo se p h M F a rl e y
Sandy Cr eek Ener gy St at ion
Limestone D G Hunt er
Sidney A M ur r ay Jr Hydr oelect r ic
Cast le Gap Solar Hybr id
Upt on Count y Solar
King M ount ain Wind Ranch 1
Sant a Rit a East
Toledo Bend
River Bend
Barry
Sant a Rit a Wind Ener gy
Oak Grove ( TX)
Panda Tem ple Power St at ion
Alam o 6
Big Cajun 2
Coughlin Power St at ion
RE Roser ock
M idway Solar - TX
M aj or Oak Power
Live Oak Wind Pr oj ect
Hog Bayou Ener gy Cent er Sant a Rosa Ener gy Cent er
Deser t Sky
Tenaska Fr ont ier Gener at ion St at ion Lewis Cr eek
Sher bino I I
Louis iana 2
Dansby
Cot t onwood Ener gy Pr oj ect Big Caj un 1 Victor J Daniel Jr Theodor e Cogen Facilit y
Thom as C Fer guson
R S Nelson
Louis iana 1
Crist
M ar shall For d
De ck e r Cre e k L a n si n g S m i th
Rancher o Wind Far m LLC
Ja ck Wa tso n
St . Char les Power St at ion ( LA)
Buckt hor n West ex
Acadia Ener gy Cent er Chevr on Oil
Geis m ar Cogen
Lost Pines 1 Power Pr oj ect Channelview Cogener at ion Plant
ExxonM obil Beaum ont Ref iner y
LaO Ener gy Syst em s
T H Wh a rto n Shell Chem ic al
Sand Hill
Plaquem ine Cogener at ion Plant
Opt im Ener gy Alt ur a Cogen LLC PPG Power house C
Winchest er Power Par k PPG River side
Gr eens Bayou
Geis m ar
Wat er f or d 1 & 2 Little Gypsy
Bast r op Ener gy Cent er
S i m Gi d e o n
Pasadena Cogener at ion
Shell Deer Par k
Bayt own Ener gy Cent er
Sabine RS Co g e n
Bayou Cove Peaking Power
Axial Plaquem ine
Car vile Ener gy LLC
ExxonM obil Bayt own Tur bine
Fayet t e Power Pr oj ect
Hays Ener gy Pr oj ect
Guadalupe Gener at ing St at ion
Dow St Char les Oper at ions
Sabine River Wor ks
Nine Mile Point
Rockspr ings Calc asieu Te ch e
Sabine Cogen
Channel Ener gy Cent er LLC
Cedar Bayou M ot iva Ent er pr is es Por t Ar t hur Ref iner y Wa te rfo rd 3
Rio Nogales Power Pr oj ect
W A Parish Exelon LaPor t e Gener at ing St at ion
Cedar Bayou 4
LEPA Unit No. 1
Taf t Cogener at ion Facilit y
O W S o m m e rs Ba cl i ff
Leon Cr eek
J K Spruce Deer Par k Ener gy Cent er
Power St at ion 4
Houm a
Bayou Cogen Plant
Color ado Bend I I Gre e n P o we r 2
Jack Fusco Ener gy Cent er
Ar t hur Von Rosenber g Texas Cit y Power Plant
Newgulf Cogen
J T Deely Sam Raybur n Color ado Bend Ener gy Cent er
Oyst er Cr eek Unit VI I I
Pear sall
V H Braunig Sweeny Cogen Facilit y
Fr eepor t Ener gy Cent er
Vi cto ri a
ERCOT sometimes gets
Fr eepor t Ener gy
For m osa Ut ilt y Vent ur e Lt d
Co l e to Cre e k CFB Power Plant
South Texas Project
San M iguel
Papalot e Cr eek I I LLC
Kar ankawa Wind LLC
more than half its electric
M idway Wind, LLC
Papalot e Cr eek I LLC
Gr egor y Power Plant
Nueces Bay
I ngleside Cogener at ion
Cedr o Hil Wind LLC
Tor r ecilas Wind Ener gy, LLC
Cor pus Chr is t i Ener gy Cent er
Lar edo
Ba rn e y M Da v i s
Whit et ail
energy from wind!
Pat r iot Wind Far m
Javelina Wind Ener gy I I , LLC
Chapm an Ranch Wind I
Javelina Wind Ener gy, LLC
Baf f in Wind
Sender o
Penascal I I Wind Pr oj ect LLC
Penascal Wind Power LLC
St ella Wind Far m Pat t er n Gulf Wind
Rio Br avo Windpower , LLC
M est eno
Br uennings Br eeze Wind Far m
Hidalgo Wind Far m LLC Red Gat e Power Plant
M agic Valley Wind Far m I LLC
Los Vient os Windpower I I I
Los Vient os Wind 1A
Hidalgo Ener gy Cent er
Los Vient os Windpower I V
Los Vient os Wind 1B
M agic Valley Gener at ing St at ion
Cam er on Wind 1 LLC
Silas Ray
5
Texas Generation Sources and Home
Heating Sources
Image Source: www.eia.gov/todayinenergy/detail.php?id=47116
Texas population is growing, increasing 16% from 25.1 million in 2010
to 29.2 million on 2020
6
Texas Population Density
85% of population
is along or east of
the I35 corridor
(DFW to Waco to
Austin to San
Antonio to Laredo)
7
Texas Near Total Blackout,
February 14-18, 2021
• Unfortunately electric grids often make the news for
all the wrong reasons!
• Starting on Feb 14, 2021 statewide
Texas had temperatures much
below avg., though not record cold
– In College Station on Feb 15 is low was 9F and very windy
(and 5F on Feb 16); avg. high is 65F and low of 45F
– Our record low is -3F (1/31/1949), our
coldest February temperature was 5F
(2/5/1951) and last single digit was 9F
(12/22/1989)
• This stressed many infrastructures
including the ERCOT electric grid
8
ERCOT Generation Feb 11-18, 2021
Image source: New York Times, Feb 23, 2021
9
Important Electric Grid Considerations
• Electricity cannot be economically stored
– Generation must be continually adjusted to match changes
in electric load and losses
• Electric power flows on high
voltage transmission lines
cannot usually be
directly controlled
– Control is mostly indirect,
by changing generation
• Customers have been in control of their load
• Transmission system has finite limits; often operated
close to its limit for economic reasons
10Electric Grid Time Frames
Image: Sauer, P.W., M. A. Pai, Power System Dynamics and Stability, Stripes Publishing, 2007
11Quick Aside: Power System Dynamic
Response to Load/Gen Mismatch
• An electric grid frequency is constantly changing, but it
usually within a few mHz of desired (e.g., 60 Hz)
• Too much generation increases the frequency and
too little decreases it
• All grid elements
have the same
average frequency
but during
disturbances the
frequency can
oscillate
12ERCOT Frequency, Feb 15, 2021
Image source: ERCOT Presentation by Bill Magness, February 25, 2021
13ERCOT Load Shed and
Rotating Blackouts
• The vast majority of the lost load was due to load
shed and then rotating blackouts
ERCOT peak load is
74.8 GW (summer);
winter peak of 69.2 GW
was set on 2/14/21
Image source: ERCOT Presentation by Bill Magness, February 25, 2021
(previous winter peak
was 65.9 GW)
14How can Grids Cascade?
• ERCOT reported that they were minutes away from
a catastrophic blackout that would have taken down
the entire grid, requiring many days to restore
• Grids can cascade due to a number of different
reasons with many related to the transmission grid
flows and voltages
• For ERCOT the situation was the
prolonged (minutes) low frequency
would have result in generators
tripping due to under frequency
resulting in a cascading collapse
in the frequency and hence the entire system
15How Much Generation Capacity was Lost?
This and following images are from a 4/27/21 ERCOT presentation
16How Much Generation was Lost?
This slide
recognizes
what would
actually have
been available
17Lost Natural Gas Generation
Sunday Monday Tuesday Wednesday Thursday Friday
30 (2/14) (2/15) (2/16) (2/17) (2/18) (2/19) Existing
GW
Outages Fuel
25 Limitations
GW Miscellaneous
Equipment
20
GW Issues
Transmission
15 Loss
GW
Weather
Related
10
GW Frequency
Related
5
GW
0
GW
18Winterizing Wind Turbines
• In general wind turbines can operate in quite low
temperatures
• However, most of the wind turbines in Texas were
not configured with the systems needed to deal with
low temperatures
– They mostly were not available because of turbine blade
icing
• Wind turbines can be winterized with systems such
as heated blades or coatings; packages can also be
installed to protect the gearbox and motors, such as
adding heating to the nacelle
19Why Were Electric Prices High?
• In ERCOT, like much of the rest of the country,
electricity is priced using a locational marginal price
(LMP) market, that has both day-ahead and real-time
markets
– The price of electric varies by
location and time of day
• Usually the price is relatively low
say $30/MWh (or $0.03 by kWh)
• It had been capped at $9000/MWh
but this was recently lowered in
March 2021 to $2000/MWh
• Operating for days at price was considered unlikely!
20Background: Why is ERCOT Separate
• ERCOT operates asynchronous from the rest of
North America, but has high voltage dc (HVDC) ties
with the Eastern Interconnect and Mexico
• The advantage is ERCOT avoids some federal
regulation. The legal basis for this is complex,
based on the US Constitution,
the Federal Power Act,
the 5/4/76 midnight
connection, other
legislation, court rulings,
and FERC decisions
Image Source: aect.net/documents/2017/AECT%20LSB%20012617.pdf
21High Voltage Direct Current
(HVDC) Transmission
• Most electricity is transmitted in ac form, at either 60
or 50 Hz (with 60 Hz in North America)
• HVDC is sometimes used to transmit electricity
either within an interconnect or between
interconnects (back-to-back HVDC)
– Within an interconnect, HVDC is usually used for long
distance transfer, or in underground or undersea cables
• HVDC avoids issues with reactive power, but incurs
the costs associated with the rectification (ac to dc)
and inversion (dc to ac)
• HVDC power flow can be quickly controlled
(milliseconds)
22Southern Cross HVDC
Transmission Project
• The Texas Public Utility Commission has approved
an application to build a 38 mile, 345 kV ac
transmission line to connect to a 400 mile long, 500
kV HVDC between the Mississippi/Alabama and the
Louisiana/Texas borders
– As planned it would have a capacity
of 2000 MW
– It could be operational in 2022 with a
cost that might be more than $1 billion
– Up-to-date information on the project is
available at
www.ercot.com/mktrules/puctDirectives/southernCross
Image source: southerncrosstransmission.com/wp-content/uploads/2021/03/SC_factsheet_2021_V3.pdf
23Joining the East and West Grids
• In 2020 we did a research project for SPP looking at
an ac interconnection of the East and West grids
– This did not include ERCOT, but did include parts of Texas
• There are nine locations where the grids are close
and could be tied together
• The study required lots of dynamic simulations using
quite detailed full system models (transient stability
level, 110,000 buses)
• The result was there are no show stoppers to doing
this, and there could be good benefits!
24East-West Combined Grid
The study included Canada but we did not consider any ac
interconnections between the grids in Canada; the grids were
connected at nine points from Montana to New Mexico
25WECC Frequency Response:
With and Without the AC Interconnection
The graph
compares the
frequency
response for three
WECC buses for
a severe
contingency with
the interface
(thick lines) and
without (thin
lines)
26AC-Tie Interface, Severe Contingency
Interface 2001 (EI_To_WECC_AC) MW
2,600
The large, and
2,400 seemingly
2,200 persistent,
Interface 2001 (EI_To_WECC_AC) MW
2,000
change in the
1,800
1,600
interface flow
1,400 required the
1,200 need for
1,000
modeling the
system’s longer
800
600
400 term AGC
200 response.
0 5 10 15 20 25 30
Time
Interface 2001 (EI_To_WECC_AC) MW
27Adding AGC Modeling
• As noted following any disturbance about 80% of
the governor response will occur in the East, with
the change in flow going across the new ac interface
if the disturbance is in the West.
• The governors don’t restore the system frequency to
its setpoint value; rather this is done by the
automatic generation control (AGC) utilizing the
balancing authority area control error (ACE) signal
• The ACE has a frequency component
ACE = Pactual - Psched – 10b(freqact - freqsched)
b is the frequency bias; it has a negative sign, units of
MW/0.1 Hz and is about 1% of the peak load/generation
28Interface Flow with AGC Modeling
The AGC studies were
2,600
2,400
run for up to six minutes
2,200
with emergency
Flow (East to West) MW
2,000
1,800 transactions
1,600
1,400
implemented. Graph
1,200
shows a WECC
1,000
800 generator loss
600
400
contingency with the
200 emergency transactions
0
0 30 60 90 120 150 180
Time (Seconds)
210 240 270 300 330 360 between WECC utilities.
MW, Interface 2001 (EI_To_WECC_AC)
How fast the interface
b
c
d
e
f
g
flow returns to normal
depends on how fast the
MW transactions ramp.
29Situational Awareness
• A key challenge with this project was understanding
the results of these dynamic studies
– Even a 30 second study produced many GBs of results
• Situational awareness (SA) is defined informally as
“knowing what’s going on” and more formally as “the
perception of the elements in the environment within
a volume of time and space, the comprehension of
their meaning and the projection of their status in
the near future”
• In this study we wanted to have good SA to make
sure we didn’t miss something
30Situational Awareness Techniques
• For this project we leveraged a number of different
techniques and developed some new ones including
– Time-domain graphs
– Geographic data views including planar flow visualizations
– Contours
– Animation (movies)
31Results Example at 2.0 Seconds
This
visualization is
using geographic
data views and a
contour to show
the response of
the 110,000 bus
model; red
values are
frequencies less
than 60 Hz
32Results Example at 12 Seconds and
Three Minutes
Bottom image shows the
results after three minutes,
with the AGC response
allowing the generator loss
to be picked up with WECC
33ERCOT-East-West Transmission
Orange is
345 kV,
Red is 500
kV
An ac interconnection would probably be the least expensive approach
to greatly increase the ERCOT import/export capability
Public Source Map: www.nerc.com/comm/CIPC/Agendas%20Highlights%20and%20Minutes%202013/2015%20December%20Compiled%20Presentations.pdf
34Broadening to Electric Grid Resiliency
• The ability of electric grids to resiliently respond to
high impact, low frequency events is an important
but often overlooked aspect of operation, design
and research
– There is always a tradeoff between risk and mitigation cost
• The best reference we know of is the free 2017
report from the US National Academies titled,
“Enhancing the Resilience of the Nation’s Electricity
System”
– It does mention the threat of cold weather, and specifically
mentions the February 2011 Texas cold snap
35The Grid Needs to Be Resilient to Lots of
Disturbances on Different Time Frames
• Events short and long-term
– Lightning strikes can usually be
cleared within seconds
– But ice, tornados and hurricanes can
bring large-scale damage over long
timer periods
• Need to consider all operating
conditions
Image Derived From L.H. Fink and K. Carlsen, Operating under stress and strain, IEEE Spectrum, March 1978, pp. 48-53
36Some Electric Grid Risks
(National Academies 2017 Report)
37Some Electric Grid Risks
Ice storms
Earthquakes
And many more! But all
need to be considered from
a risk/benefit perspective
Hurricanes Hurricane risk image source: USGSHigh-Impact, Low-Frequency Events
• In order to enhance electric grid resiliency we need
to consider the almost unthinkable events
• These include what the
North American Electric
Reliability Corporation
(NERC) calls High-Impact,
Low-Frequency Events
(HILFs); others call them Image Source: NERC, 2012
black sky days
– Large-scale, potentially long duration blackouts
– HILFs identified by NERC were 1) a coordinated cyber,
physical or blended attacks, 2) pandemics, 3) geomagnetic
disturbances (GMDs), and 4) HEMPs
39Cyber-Physical Considerations • Effectively operating the grid involves a heavy interaction between humans, the cyber and the physical; maintaining situational awareness will be key and is a crucial area for more research • This is an often overlook area of research because it is so challenging. • The number of couplings between the grid and other infrastructures is growing – Electrification of transportation • We need realistic simulations that can consider key aspects of the electric grid and coupled infrastructures
Increasing Resiliency
• The National Academies 2017 report has lots of
specific recommendations
• All recommendations need to be considered from a
cost-benefit point of view
– we can’t prevent all blackouts, but we need to mitigate the
effects of severe HILF events
• Electric grid analysis tools need to be designed to
handle severe events, allowing events to be
simulated and appropriate mitigation plans to be
developed
– What would we do if “?” Example, if temperatures in
College Station went to -3F (like in 1949)?Conclusion
• The electric grid is crucial to our society, and for
decades into the future we will be relying on it
• The Texas 2021 event illustrates a vulnerability
• A perfect electric grid is impossible, and we need to
be prepared for long-term, wide-area blackouts
• However, much can and should be done to reduce
to reduce this risk
• A broad, sustained effort is needed in this area
including the entire electric grid sector
• Focusing on the interaction between the cyber,
physical and the humans will be key
42Thank you and Questions
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