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This article discusses the weather and nature challenges faced by ERCOT during the summer of 2011, as well as the variables leading to Energy Emergency Alerts (EEAs) and the mitigating actions taken. It also provides an outlook and changes for Summer 2012.
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ERCOT Experiences During Summer 2011 Joel Koepke, P.E. ERCOT Operations Support Engineer
Objectives • Identify weather and nature challenges • Identify variables leading to EEAs • Identify mitigating actions of August 4th EEA • Identify outlook and changes for Summer 2012
Wildfires West Texas fires in March through May
Average Min/Max Load Values June – August of 2009 - 2011
2011 EEA Procedure 1 2A 2B 3
PRC • Physical Responsive Capability (PRC) • A representation of the total amount of system wide On-Line capability that has a high probability of being able to quickly respond to system disturbances
June 27th EEA Highlights • 3 unit trips in less than 2 hours • Total of 1,800 MW • Large wind decline • Drop of 4,200 MW in 4 hours • Large load increase • Increase of 4,000 MW in 2 hours • Below 2,300 MW of Reserves for 1 minute • EEA lasted for 1 hour and 25 minutes
June 27th EEA- Wind and Load Unit Trips
August Peak Loads 8/3: Record Peak
Variables Affecting Physical Responsive Capability • Online generation • System load magnitude • Resource outages and derates • Wind output • DC tie imports
August 4th EEA Level 2B Load Resources and EILS deployed
August 04, 2011 - EEA Level 2B • Issued OCN • Projected reserve capacity shortage for hours 14:00 through 21:00 Cancelled EEA 1 Issued Watch Reserves below 2,500 MW ERCOT ran out of regulation and issued manual Responsive Reserve deployment Move to EEA 2A From EEA 2B Cancelled OCN Load Resources Recalled 1,392 MW Non-Spin deployed August 4 Watch for extreme heat still in effect 2:15 PM 0:06 AM 1:25 PM 3:44 PM 5:53 PM 6:52 PM 8:49 PM 12:38 PM 1:45 PM 2:32 PM 4:05 PM 6:09 PM 8:38 PM 10:17 PM Cancelled Advisory EILS Recalled EILS deployment Business Hours 3 Issued EEA 1 Reserves below 2,300 MW • Issued EEA 2A • Reserves below 1,750 MW • Load Resources deployed • Issued EEA 2B • EILS Deployed • Business Hours 2 Cancelled Watch • Note:Watch also include: • Qualified Scheduling Entity Hotline Call • Transmission Operator Hotline Call • Postings on the Market Information System and ERCOT website Issued Advisory Reserves below 3,000 MW Move to EEA 1 From EEA 2A
DC Tie Imports: 8/4/2011 216 MW • ERCOT had a max import of 1,039 MW across the DC Ties • East DC Tie= 594 MW • North DC Tie= 216 MW • South DC Tie=229 MW 229 MW 594 MW 1,039 MW
ERCOT Load, Online Capacity, Offline Non-Spin and Net DC flow
ERCOT CDR - Report on the Capacity, Demand, and Reserves in the ERCOT Region • Long-term planning tool • Uses normalized assumptions • Normal weather basis • Does not include Resource outages • Summer Summary released in December of 2011. • Peak Demand – 66,195 MW • 64,618 MW firm load • 738 MW of firm load added since June CDR • Available Capacity – 72,444 MW • Reserve Margin – 12.11%
Seasonal Assessment of Resource Adequacy (SARA) • New report • Evaluates near-term Reserve adequacy • Uses more recent seasonal climate forecast • Accounts for specific events (e.g. Drought) • Evaluate the range of reserves usage in a deterministic manner • Uses of reserves: • Higher peak demands due to above normal weather • Forced generation outages • Planned generation outages • Atypical issues like drought • Lower wind availability • Determines the likelihood of Reserves dropping below the 2,300 MW threshold.
Emergency Interruptible Load Service (EILS) • Proposed Changes • Allow Distributed Generation and unregistered generation to participate • New capacity • Remove the 1 MW minimum offer • Improve QSE flexibility • Increase participation • Explore the possibility of a 30-min product • Increase participation