1. Intermittent Resources and Demand Response Integration –2016 Long-Term Reliability Assessment Workshop
Bill Bojorquez
VP, System Planning
August 16, 2007

2. NORTH AMERICAN ELECTRIC RELIABILITY CORPORATION (NERC)
North American Interconnected Grids
NORTH AMERICAN ELECTRIC RELIABILITY CORPORATION (NERC)
The ERCOT grid:
Covers 75% of Texas land
Serves 85% of Texas load
38,000 miles of transmission lines
>550 generation units
Physical assets are owned by transmission providers and generators, including municipal utilities and cooperatives
ERCOT connections to other grids are limited to direct current (DC) ties, which allow control over flow of electricity

3. Current Wind Development
~3,300MW installed capacity of wind generation in-service
~2,000MW additional wind development with signed interconnection agreements
Steady build out has allowed for transmission, modeling and operation integration
Additional bulk transmission lines will be
required for > ~5000MW from West Texas
~29,000 MW additional wind development in interconnection study process

4. ERCOT Load 62,339 MW summer peak demand
Majority of load is concentrated in eastern half of state
Dallas
Austin
Houston
San Antonio

5. Effective Load Carrying Capability (ELCC) of Wind
Process:
Run the ERCOT LOLP model with the base set of generating units and a generic thermal generator (550 MW) and determine the expected unserved energy.
Remove the generic thermal generator and add new wind generation with detailed profiles until the same expected unserved energy is achieved.
The amount of new wind generation will have the same effective load-carrying capability as the 550-MW generic thermal generator
Update study every two years
Results:
6,300 MW of wind had the same load carrying capacity as 550 MW of thermal generation (i.e., 8.7%).
Describe the process for wind.

6. Increased renewable energy goal 5,880 MW by 2015 10,000 MW by 2025
TX Senate Bill 20 (2005)
Increased renewable energy goal
5,880 MW by 2015
10,000 MW by 2025
Set up process for the PUC to designate Competitive Renewable Energy Zones (CREZs)
ERCOT contracted AWS Truewind to identify areas with best wind resource potential in Texas
AWS identified highest CF 100MW sites and clustered into 25 areas

7. Potential Wind Resource
12000
Potential Wind Resource
10600
9600
8300
2700
Nearly 100,000 MW above 35% capacity factor (CF)
Concentrated in western half of state
4600
2200
6200
6000
2900
7900
6900
4700
Approximate
west to east transfer
capacity – 3,200MW
3000

8. New Transmission Required
12000
New Transmission Required
10600
9600
8300
2700
Existing system from west Texas fully subscribed
Significant distances and costs associated with adding bulk transmission
4600
2200
200 miles
6200
6000
2900
7900
6900
4700
150 miles
3000

9. Allowed for incremental 1,000 to 5,000 MW of wind capacity
ERCOT Study Results
ERCOT’s 2006 study identified new lines and upgrades to allow transfers from CREZ areas
Allowed for incremental 1,000 to 5,000 MW of wind capacity
In addition to 5,000 MW existing plus planned
Goal was to provide options from which the PUC could designate areas and amounts

10. Draft CREZ PUCT Designations (Scenario 3)
3720
Wind Zone
Planned New Wind Capacity (MW)
1, 2
4,560 4
3,720
5, 6
2,890
9,10
5,215 19
2,051
Total
18,436 4
4560
1, 2
5215
2051
9, 10 19
2890
5, 6

11. Level of wind penetration relative to the size of the interconnection
Challenges
Level of wind penetration relative to the size of the interconnection
Minimum system load dispatch issues (~ 21,000 MW)
Ancillary Services to support large wind changes
Voltage and transient stability modeling and assessments MW
Noon
Midnight
Completing system reviews for the CREZ designations over the next six months

12. Next Steps
Stage 1 (August): Final order in Docket on CREZs and “rough” transmission requirements
Stage 2 (December/January): Completion of “CREZ Transmission Optimization Study”
Stage 3 (December/February): PUC to designate transmission constructors
Stage 4 (December ’08/February ’09): CCNs developed and submitted
Stage 5 (June ’09/August ’09): CCNs approved
Stage 6 (TBD): Completion

13. Demand Response

14. Target for reliability: 12.5%
Reserve Margins
Percentage difference between projections for peak demand and available generation/resources
Target for reliability: 12.5%
Over 65,000 MW of new generation is in planning or under consideration, but not all will be built.
12.5%

15. Interruptible Tariffs in the Regulated World
Prior to 2001, 3200 MW of customer load (mostly industrials) provided an emergency interruptible safety net
Customers’ year-round electric rates were discounted in exchange for this
In May 2000, ERCOT deployed interruptible loads four times during emergency conditions
Unseasonably hot weather
Generation outages
New wave of gas-fired generation had not yet come online
ERCOT began full retail competition on January 1, 2002

16. Interruptible Load in the New (restructured) Market
Loads Acting as a Resource:
Market-based replacement for interruptible tariffs
1,989 MW currently registered and qualified
ERCOT demand forecast is reduced by 1,112 MW of “high confidence” demand response
LaaRs can provide ERCOT Ancillary Services (operating reserves) & receive capacity payments regardless of whether they are actually deployed
LaaRs provide 50% of ERCOT Spinning Reserve requirement (1,150 MW of 2,300 MW total)
Market price: ~$13 per MW per hour
Price-responsive demand is significant in ERCOT – but not yet readily reported
Additional demand response is obtained on coincident peak periods due to Transmission Tariff incentive

17. LaaR Participation
Growth in LaaR registration in MW

18. LaaR Deployments
LaaRs can be deployed in 4 ways:
Automatic trip based on Under Frequency Relay settings
Verbal dispatch by ERCOT during EECP event (deployed as block)
Verbal dispatch by ERCOT during frequency event reportable to NERC (deployed as block)
Verbal dispatch by ERCOT to solve a local congestion issue (location-specific)
LaaRs have been deployed four times in the past 16 months:
April 17, 2006 Emergency Electric Curtailment Plan (manual)
Oct. 3, 2006 frequency event (manual)
Dec. 22, 2006 frequency event (UFR & manual)
July 2, 2007 frequency event (manual)

19. Emergency Interruptible Load Service (EILS)
Service provided by loads (customers) willing to interrupt during an electric grid emergency in exchange for a payment
Last resort prior to firm load shedding (rotating outages)
Deployed ONLY in the late stages of a grid emergency
Goal is 500 MW to 1,000 MW subscription
Minimum subscription not met for spring and summer 2007
New RFP out for fall 2007
‘Another tool for the operator toolbox’

20. Deployment During Emergency Operations
Event/Action
Trigger
ADVISORY
Physical responsive below 3000 MW
ALERT: Start Reliability Must Run units, suspend unit testing, deploy Replacement & Non-spin Reserves
Physical responsive below 2500 MW
Emergency Electric Curtailment Plan
Step 1: Dispatch all generation, issue public media appeal, acquire maximum power thru DC Ties
Physical responsive below 2300 MW
Step 2: Deploy LaaRs
Physical responsive below 1750 MW
Step 3: Deploy EILS Resources
Maintain frequency at 60 Hz
Step 4: Instruct transmission owners to shed firm load
Frequency below 59.8 hz
ERCOT Operators have flexibility to skip Step 3 if frequency is decaying rapidly. In these cases EILS would be deployed immediately after Step 4 to enable faster recovery.

21. Consideration on Demand Response (DR)
Should DR be considered a firm resource? If so what types of DR
Does DR defer transmission investment?
ERCOT concluded it should not
Summer 2006 MISO experience showed DR may not be useful unless transmission additions are made
Does DR stifle development of newer, more efficient, and cleaner generation resources?

22. Q&A
Questions? ON
OFF