Overview of January 6 EEA Event

Chad ThompsonManager, Operations Support ROS

ERCOT PublicMarch 6, 2014

2

Event Summary – January 6, 2014

• At 6:52, ERCOT declared Level 1 of its Energy Emergency Alert (EEA) and declared EEA Level 2 at 7:01, primarily due to the loss of a number of generating units

• Non-Spin Reserve Service (NSRS), Load Resources (LR) and Emergency Response Service (ERS) were deployed, but firm load shed was not required

• ERCOT moved from EEA2 to EEA1 at 7:51 and resumed normal operations at 9:12

• Generation outages & derates peaked at 9355 MW just before 07:00, with 3541 MW due to weather

• Hourly peak demand was 55,487 MW for HE08 and instantaneous peak demand was 56,478 MW at 07:08:24

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07:51 AMERCOT recalled EEA Level 2. EEA Level 1 remains in effect07:56 AMERCOT recalled 30 minute ERS07:58 AMERCOT recalled 10 minute ERS.

ERCOT deployed RRS to Generators for frequency below 59.91 Hz

06:37 AM 06:52 AM

ERCOT deployed Non-Spin for 187 MW

ERCOT deployed Group 1 RRS for 546.36 MW

07:43 AMERCOT recalled all Group 2 RRS07:50 AMERCOT recalled all Group 1 RRS

06:42 AM 09:12 AM

07:02 AMERCOT deployed 30 minute ERS for 111.68 MW07:05 AMERCOT deployed 10 minute ERS for 508.72 MW07:13 AMERCOT recalled all RRS from Generators due to frequency above 59.91 Hz

06:57 AM

Watch terminated as PRC was above 3000 MW

09:55 AM

Watch issued due to PRC below 2500 MW

ERCOT issued EEA Level 2 for PRC below 1750 MW

ERCOT deployed Group 2 RRS for 536.24 MW

ERCOT issued EEA Level 1 for PRC below 2300 MW

06:52 AM 07:01 AM

EEA Level 1 cancelled. Watch remains in effect.

08:10 :36 AMERCOT recalled all Non-Spin08:10:48 AMERCOT deployed RRS to Generators for frequency below 59.91 Hz08:17 AMERCOT recalled all RRS from Generators due to frequency above 59.91 Hz

06:42 AM

Timeline – January 6, 2014 EEA

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EEA Steps

Maintain 2,300 MW of on-line reserves1

2

3

Maintain 1,750 MW of on-line reserves. Interrupt loads providing Responsive Reserve Service. Interrupt loads providing Emergency Response Service (ERS).

Maintain System frequency at or above 59.8 Hz and instruct TSPs and DSPs to shed firm load in rotating blocks.

EEA procedure in the ERCOT Protocols defined by levels

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Event Highlights

• Weather was warmer than February 2 2011

• Load and Wind Forecast error were within acceptable margins

• 9355 MW forced out/derated/failed to start by HE07; 3541 MW due to weather, and 2468 MW planned out & 2938 MW forced out going into the operating day (14,761 MW)

• 97 units experienced forced outages/derates, or failure to start from 00:00 to 23:59 on 1/6/14

• 1 unit committed in DRUC, no units committed in HRUC

• Responsive Reserve from generation was deployed in response to low frequency events

• Load Resource performance was 94 %

• SCED was able to manage congestion

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Forecast Comparison

• Weather was warmer than February 2, 2011, and cooler than January 7 when the load was higher (57,277 MW)

• MTLF MAPE was 2.29 % for the day (metric is 3.5-4%)

• WPF Error was 8.1 % for the day (2013 average was 8.3%)Dallas Houston Austin San Antonio Brownsville MidlandTemp Wind Temp Wind Temp Wind Temp Wind Temp Wind Temp Wind

2-Feb-11 5AM 14 17 22 10 18 20 20 13 34 18 9 176AM 14 15 21 14 19 17 20 20 33 13 8 157AM 14 20 21 16 19 18 20 17 33 20 7 168AM 13 20 22 18 19 18 20 16 33 16 7 16

6-Jan-14 5AM 2 7 6 -8 7 3 11 -2 10 3 7 4EEA2 6AM 2 2 7 1 5 2 10 4 10 -2 8 256,031 MW Load HE20 7AM 1 12 6 0 3 3 8 3 9 6 7 3

8AM 4 11 5 9 3 5 7 1 9 -1 7 47-Jan-14 5AM 8 8 1 5 0 20 5 13 5 9 11 1713/14 Winter Peak 6AM 8 6 3 14 -4 13 4 20 7 5 12 957,277 MW Load HE08 7AM 7 11 3 16 -3 18 4 17 8 12 14 9

8AM 8 11 1 14 -4 18 4 16 9 9 14 10

Temperature values shown indicate degrees warmer at this time than same time on 2/2/2011Wind values shown indicate MPH higher wind on 2/1/2011 than at this time

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Generation Outages

Note: This does not include outages which occurred before midnight on January 6

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Generation Outages

Note: This does not include outages which occurred before midnight on January 6

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Reserves

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Frequency & Physical Responsive Capability

59.8

59.85

59.9

59.95

60

60.05

60.1

0

1000

2000

3000

4000

5000

6000

06:00 06:30 07:00 07:30 08:00 08:30 09:00 09:30 10:00

Freq

uenc

y (H

z)

Pyhs

ical

Res

pons

ive

Capa

bilit

y (M

W)

Operating Hour

Physical Responsive Capability Frequency

900 MW @

06:35

214 MW 06:47

900 MW @

08:11

215 MW @

08:50

310 MW 06:59

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Ancillary Services

• ERCOT manually deployed Non-Spin from 6:42 to 8:10

• Load Resources were manually deployed with a 94 % overall performance

• Responsive Reserve from generation was deployed form 6:37 to 7:13 and again from 8:10 to 8:17

• one unit (319 MW) was committed in HRUC

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Congestion

• There were as many as 17 constraints active in SCED between 05:00 and 12:00 on January 6

• SCED was operational and able to manage congestion during this event

Constraint Contingency Description Constrained ElementD_NBCBY5 : HB_TWG66_A Northbelt - King / Cedar Bayou 345 kV Double-Circiut Humble - Treaschwig 138 kV LineDNAVLEG5 : 40__A Navarro - Limestone 345 kV Double-Circuit Big Brown - Jewett 345 KV LineDSAMTHS5 : WHTNY_FMR2 Sam Switch - Tradinghouse 345 kV Double-Circuit Whitney 138/69 kV Autotransformer # 2DTRSTRC5 : TRSES_MR6L Trinidad - Watermill / Tricorner 345 kV Double-Circuit Trinidad 345/138 kV AutotransformerDWH_STP5 : BONIVI_RINCON1_1 White Point - Lon Hill / STP 345 kV Double-Circuit Bonnieview - Rincon 69 kV LineDWLV89N8 : 3410__A West Levee - 800/900 Network 138 kV Double-Circuit East Levee Switch - Reagan Street 138 kV LineSCOLPAW5 : COLETO_KENEDS1_1 Coleto Creek - Pawnee 345 kV Single-Circuit Coleto Creek - Kenedy Switch 138 kV LineSDQNB8 : HB_TWG66_A Drilco - Northbelt 138 kV Single-Circuit Humble - Treaschwig 138 kV LineSI_DI_38 : I_DUPP_I_DUPS1_1 Ingleside Dupont Switch - Dupont PP1 138 kV Single-Circuit Ingleside Dupont Switch - Dupont PP1 Ingleside 138 kV LineSKOCNU28 : GILA_HIWAY_2_1 Gila - Koch Up River 138 kV Single-Circuit Gila - Hiway 9 138 kV LineSLAQLOB8 : BRUNI_69_1 Lobo - La Quinta 138 kV Single-Circuit Bruni 138/69 kV AutotransformerSORNLON8 : LON_HI_SMITH1_1 Lon Hill - Orange Grove 138 kV Single-Circuit Lon Hill - Smith 69 kV LineSPAWCAL5 : COLETO_KENEDS1_1 Calaveras - Pawnee 345 kV Single-Circuit Coleto Creek - Kenedy Switch 138 kV LineSSALSK28 : 6146__A Skywest - Salt Flat 138 kV Single-Circuit East Midland - Midland East 138 kV LineSSHBMLS5 : ELKTN_SD1_1 Martin Lake - Shamburger Switch 345 kV Single-Circuit Elkton Series Reactor 138 kV # 1STRSWTR5 : TRSES_MR6L Watermill Switch - Trinidad 345 kV Single-Circuit Trinidad 345/138 kV AutotransformerXLY2T58 : LYTTON_S_AT1H Lytton Springs 345/138 kV Autotransformer # 2 Lytton Springs 345/138 kV Autotransformer # 1

Operating Day January 6 2014

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Next Steps

• ERCOT and Texas RE requested additional information from generators on causes of generator trips and derates on January 6

• This additional information resulted in outaged/derated MWs changing since the TAC report on Jan 28

• ERCOT has (re)visited 4 of the units who initially reported weather-related issues on January 6 to review winterization plans

• ERCOT had already requested data to improve accuracy of wind forecast during icing and cold weather from wind generators due to November 2013 cold spell; need to add temperature limits to RARF

• Enhance procedures to directly consider increased generating capacity unavailability for unit commitment during severe cold weather events

• Reassess outage calculations used for future SARA reports to ensure derates are appropriately included

• Improve means to get updated information on generation derates and startup failures to ERCOT in near-real time

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Questions

Next Steps