Technical Review Committee Meeting March 16, 2011 Bri-Mathias Hodge Gregory Brinkman Debra Lew

NREL is a national laboratory of the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy operated by the Alliance for Sustainable Energy, LLC

Technical Review Committee Meeting March 16, 2011

Bri-Mathias HodgeGregory Brinkman

Debra LewNational Renewable Energy Laboratory

Golden, Colorado USA

Western Wind and Solar Integration Study - Phase 2: Proposed Modeling Efforts

Background: WWSIS Phase 1 Modeling

• Production simulation was conducted with GE MAPS

• WECC represented as 14 transmission zones

• 5 balancing areas

• Hourly simulation over three years

• Used 2008 Ventyx database

• WECC database - with updates - used for transmission

National Renewable Energy Laboratory Innovation for Our Energy Future

PLEXOS Overview

• MIP formulation allows the addition of constraints on generator operating regions• Can then explicitly model times when cycling occurs

• Can easily incorporate cycling and ramping costs

• Can consider these costs when making unit commitment and dispatch decisions

• Easily switches between explicit transmission modeling and zonal modeling• Can focus on certain regions to examine interesting areas

more closely

• Allows dispatch at five minute time steps• Can easily examine interesting events in further detail


PLEXOS – Renewable Integration Studies

• CAISO 20% Study

• CAISO 33% Study

• MISO Wind Integration Study


Benchmarking

• No benchmarking with Phase 1 MAPS model runs• Plan on benchmarking with TEPPC 2019 ProMod

simulations• Intended to be qualitative, not quantitative• Only need to verify that high level information is within a

reasonable range• Percentage of capacity by generator type• Percentage of energy by generator type• Total costs• Inter-area flows are of the correct order• etc…


Model Configuration - Timescales

• Timescales• Day-ahead unit commitment • Hourly dispatch

• PLEXOS allows dispatch at the five minute level• Can use this capability to examine a limited number of

interesting events

• Can use PLEXOS medium term horizon (load duration curves) in order to optimize over longer time horizons


Model Configuration – Balancing Area CooperationPossible Ideas

• Balancing authorities• 5 region

• WestConnect, Columbia grid, NTTG, CAISO, Canada

• More regions (14?)

• Cooperation between BAs• High cooperation

• Zero hurdle rates (WWSIS 1)

• Medium cooperation• High hurdle rates between BAs

on commitment

• Low hurdle rates between BAs in hour-ahead and dispatch


Model Configuration - Transmission

• Nodal representation vs. Zonal representation• Plan to use Zonal representation, as

in Phase 1• Avoids the explicit planning of low

voltage transmission for new renewable sites

• New transmission between zones• Plan to use WECC 2019/20 targets

and revise/expand with TRC input


Model Configuration - Policy

• Production Tax Credit• None in phase 1

• Fixed Operating Reserve Levels• 3% of load spinning per BA in

phase 1• Will need to address if problems

occur (e.g., load shedding)

• Carbon Tax• $30/ton in phase 1


Model Configuration - Cycling Costs

• The case that includes cycling costs will include these costs in the unit commitment and dispatch optimization algorithms• Optimize around the cycling costs instead of just adding them to the

otherwise optimal schedule• GE will also add cycling costs to the results of phase 1 study in order to

get a ceiling on maximum costs

• Cycling costs considered:• Additional start-up costs

• Hot start

• Warm start

• Cold start

• Minimum generation level costs• Additional ramping costs for both normal and fast ramp rates


Proposed Scenarios

• Plan to examine the impacts of cycling costs through scenarios that both explicitly consider and neglect the costs of cycling

• Varying levels of renewable penetration• 10%• 20%• 30%

• Mitigation strategies to be included:

• Turning off coal generators in the spring• More flexible thermal generation• etc…



Emissions analysis

Part-load and full-load properties

Data from Continuous Emission Monitors

Run PLEXOS with unit-specific heat rate curves, emission cost sensitivities

50 100 150 200 250 300

6

8

10

12

14

16

18

Ave

rag

e h

ea

tra

te (

mm

btu

/MW

h)

Gen (MWh)

Coal (Martin Drake)

0 100 200 300

6

8

10

12

14

16

18

Ave

rag

e h

ea

tra

te (

mm

btu

/MW

h)

Gen (MWh)

Combined Cycle (Front Range)

12

0 10 20 30 40 50

6

8

10

12

14

16

18

Ave

rag

e h

ea

tra

te (

mm

btu

/MW

h)

Gen (MWh)

Combustion Turbine (Fountain Valley)


NOx emissions vs. heat input, ramp rate

13

0 1000 2000 3000 4000 50000

200

400

600

800

1000

NO

x (lb

s)

HtIn (mmbtu)

Comanche (470), unit 2 (Coal Dry bottom wall-fired boiler)

-200 -100 0 100 200-200

-100

0

100

200

300

NO

x re

sidu

al (

lbs)

RampRate (mw/hr)

Correlation coefficient is 0.00

0 500 1000 1500 20000

50

100

150

200

NO

x (lb

s)

HtIn (mmbtu)

Fort St. Vrain, unit 2 (Pipeline Natural Gas Combined cycle)

-150 -100 -50 0 50 100 150-40

-20

0

20

40

60

80

NO

x re

sidu

al (

lbs)

RampRate (mw/hr)

Correlation coefficient is -0.02

NOx curves vary widely between generators

Little evidence that dynamic ramping impacts emissions

Difficulties


1500 2000 2500 3000 3500 4000200

400

600

800

1000

1200

1400

1600

NO

x (lb

s)

HtIn (mmbtu)

Comanche (470), unit 1 (Coal Tangentially-fired)

-150 -100 -50 0 50 100 150-800

-600

-400

-200

0

200

400

600

NO

x re

sidu

al (

lbs)

RampRate (mw/hr)

Correlation coefficient is -0.03

Poor fits, unexplainable residuals

Possible time lags in the system

Technical Review Committee Meeting March 16, 2011 Bri-Mathias Hodge Gregory Brinkman Debra Lew

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