Estimating Colorado River Storage Project 

Power Economics with the GTMax Model 

Presented by 

 Thomas D. Veselka 

Argonne National Laboratory 

Decision and Information Sciences Division 

Center for Energy, Environmental, and Economic Systems Analysis (CEEESA) 

Grand Canyon Monitoring and Research Center 

Technical Work Group Socioeconomic Workshop 

Arizona Department of Water Resources, Phoenix, AZ 

December 2, 2009 
Presentation Topics 

 Introduc)on*to*the*GTMax*model**

– Methods))

– Approach)

– Features)

 *Salt*Lake*City*Area*Integrated*Project*(SLCA/IP)*monthly*

simula)ons*

– Flaming)Gorge)and)Jensen)Gauge)

– Available)Hydropower)(AHP))

– Pre@schedule)and)future)power)purchases)

 GTMax*knobs*and*levers*

– Affects)on)results)
3)

The Generation and Transmission Maximization 

(GTMax) Model Optimizes Power System Operations 

1. Available Transfer Capability (ATC) 2. Locational Marginal Price (LMP) 
4)

GTMax Uses Linear & Mixed Integer 

Programming to Solve Problems Max.)

Point)

ObjecIve)

AcIvity)

Constraints)

 Scope*and*granularity*

– One)week)is)solved)simultaneously))

– Hourly)Ime)step)

 Electric*u)lity*system*components*

– Hydro)and)thermal)power)plants)

– IntermiMent)technologies)

– Firm)purchase)and)sales)contracts)

– Spot)market)transacIons)(block)&)variable))

– Customers)(electricity)demand))

– Transmission)lines)and)connecIons))

 Hydro*system*

– Reservoirs)

– Water)channels)

– River)gauges)

 Physical*and*ins)tu)onal*constraints*

– Capacity))

– Technical)minimum)

– Ramping)limits))

– Reservoir)limits)

 Grid*services*

– Spinning)reserves)

– RegulaIon)services)

Mon 

Jan 1 

Tue 

Jan 2 

Wed 

Jan 3 

Thu 

Jan 4 

Fri 

Jan 5 

Sat 

Jan 6 

Sun 

Jan 7 

Current Simulation Week 

Mon 

Jan 8 

Tue 

Jan 9 

Wed 

Jan 10 

Thu 

Jan 11 

Fri 

Jan 12 

Sat 

Jan 13 

Sun 

Jan 14 

Next 

Simulation 
SLCA/IP Components Are 

Simulated Using a Systems Approach 

GTMax)Topology)for)Salt)Lake)City)

Area)Integrated)Project)(SLCA/IP))

Monthly)&)Annual)Planning)

Glen%%

Canyon%%

Dam%

Colorado)

Wyoming)

Utah)

New)

Mexico)

Arizona)

Source:%BOR%

%GTMax%Uses%a%Network%Representa>on%of%a%Power%System%

%All%Aspects%Are%Connected%in%Time%&%Space%
6)

Model Operations Reflect Physical Limitations, 

Environmental Restrictions, and Institutional Policies 

Up)Ramp)

Limit) Down))

Ramp)

Limit)

Daily)

Change)

#)of)Ramp)

Cycles)

Load)Following)

Preference)

Maximum%Release%Rate%

Minimum%Release%Rate%
Hydropower Dispatch Is 

Constrained by Reservoir Limitations 

 Maximum*reservoir*eleva)on*level*

 Minimum*reservoir*eleva)on*level*

 Daily*reservoir*eleva)on*change*

 Change*over*a*3Iday*period*

 Eleva)on*levels*are*func)ons*of:*

– IniIal)reservoir)condiIons)

– Hourly)up@stream)reservoir)releases)

– Side)flows)

– Hourly)reservoir)releases)

– ElevaIon/volume)funcIon)

CurecanI)

SubstaIon

Blue))

Mesa

Crystal

Morrow))

Point

To)

Montrose

To)Four)

Corners

RegulaIon)Dam)

Hourly))

FluctuaIons)

Hourly))

FluctuaIons)

Black)

Canyon)
8)

Recent GTMax Model Result 

Aspinall Cascade
9)

Reservoir%

Releases

Yampa%

Inflows

Hourly Powerplant Operations Can also 

Be Constrained by Gauge Limitations 

Capacity:%% %152%MW%

Genera>on:%%767%GWh/yr%

Opera>ons%Are%Restricted%

by%Jensen%Gauge%Limits%

(Releases(

Flaming(Gorge(

Yampa(Flows(

Gauge(Flows(

Jensen((

(GTMax(((((

SSARR((((

WTTD(Model
Transmission Line Losses Are 

Specified as a Step Function 

Line Flow (MW)

Incremental Losses (Percent)

0

2

4

6

8

10

12

75 150 225 300 375

Losses(Must(Increase(as(a((

Func@on(of(Line(Flow((

TH%

100%MW%

Genera@on((

Level(

AZ%

94%%MW%

Energy(Delivered(

to(the(End(Node(

100%MW%to%AZ%

Energy(at(the((

Beginning(of(the(Link(
Units that Provide Ancillary Service Have a 

Reduced Range of Scheduled Operation 

 Spinning*reserves*(SR)*

– Affects*maximum*genera)on*

 Regula)on*services*(RS)*

– Affects*both*the*minimum*&*

maximum*genera)on**

 Minimum*genera)on*

– When*genera)on*is*offIline*the*

unit*cannot*provide*regula)on*

services*

 Glen*Canyon*Dam*excep)on*criteria*

Minimum Load**Following

Minimum Load*Following

Increase**

Minimum*

Decrease**

Maximum*

Regula)on*

Service*

Spinning*

Reserves*

Capability*(MW)*

Up

Down
SLCA/IP Monthly Simulation Topology 

Flat(Flow(

Flat(Flow(

Reservoir(Constraints(

Gen(@(Capacity(

During(Highest((

Priced(Hours(

Min(&(Ramp(

Restric@ons(

Gauge((

Limits(

Min,(Max,(Ramp((

&(Daily(Change(

Restric@ons(

AHP(Load(

Project(Use(

Small(Project(Gen(

Transmission(

(Losses(

Montrose*Opera)ng*Guidelines

%Customer%Load%Following%or%Maximize%Economic%Value%

%On%&%Off%Peak%Periods%

%Block%&%Variable%Spot%Market%Transac>ons%

%Iden>cal%Nightly%Minimum%Releases%at%Glen%Every%Night%

%Maximum%Change%in%Daily%Release%Volumes%

%Blue%Mesa%Daily%Release%Volumes%(Zero%During%Some%Days)%
2nd(GTMax((Simula@on(

Available%Hydropower%(AHP)%

SSARR(Model(

Green%River%Flow%Rates

1st(GTMax(Simula@on(

Flaming%Gorge%Releases%

%Jensen%Gauge%Flows%

Market(Price(Spreadsheet(

Palo%Verde%Market%Hub%

BOR(24UMonth(Study(

%Reservoir%Eleva>on%(MWh)%

%Water%release%(TAF)%

3rd(GTMax((Simula@on(

SLCA/IP%%Dispatch%

Plant(Opera@ng(Criteria

%Daily%Change%(cfs/day)%

%Hourly%Ramp%Limits%(cfs/hr)%

%Maximum%Flow%Limits%(cfs)%

%Minimum%Flow%Limits%(cfs)%

Model(Results(Spreadsheets(

Perform%Calcula>ons,%Create%Tables%&%Graphs

Fixed(Flaming((

Gorge(Opera@ons(

Dispatch(Guidelines

%Load%following%

%Weekend%releases%

Customer(Load(Shaping(

Hourly%Profiles%

GTMax(Input(Spreadsheet(

Process,%Prepare,%&%Format%Data

System(AWributes(

%Plant%Capaci>es%

%Power%Curves%

%Firm%Purchases%

%Etc...%

Monthly and Annual Planning 

Modeling Process 

Final(Decision(

Reclama@on(

Final(Decision(

Western(

Sent(to(SLC(

&(Montrose(
14)

Recent GTMax Model Result 

Flaming Gorge and the Jensen Gauge 1st(GTMax(Simula@on(

Flaming%Gorge%Releases%

%Jensen%Gauge%Flows%
2nd(GTMax((Simula@on(

Available%Hydropower%(AHP)%

Max(

AHP((

Less(

Project(

Use(

35%((Seasonal(CROD(

Contract((

MSR(

Range(

Ceiling(

Seasonal((

CROD(

Monthly(

SHP(

Firming(

Purchases(

CRSP(Firm(

Contract(

Range(

Excess(

Maximum(SLCA/IP(

Less(Losses(&(Project(Use(

Firm(Offer(≥(SHP,(but(

≤(Seasonal(CROD(

Ceiling(

Floor(

Minimum*Schedule*Requirement*(MSR)*

Sustainable Hydropower (SHP),*&*

Available Hydropower (AHP) AHP(Capacity(

AHP(Energy(
Customer(Load(Shaping(

Hourly%Profiles%

Based*on*AHP*Offers*and*the*MSR**

Customer*Hourly*Loads*Are*Approximated*
17)

Recent GTMax Model Result 

Pre-schedules Results

3rd(GTMax((Simula@on(

SLCA/IP%%Dispatch%

Block((

Purchases(
Customer(Scheduling(

Hourly%Energy%Requests%

2nd(GTMax(Simula@on(

Without%BHBH%Scenario%

Contracts(Spreadsheet((((

•%Monthly%Energy%(MWh)%

•%Monthly%Capacity%(MW)%

•%Monthly%MSR%(MW)%

1st(GTMax(Simula@on(

Flaming%Gorge%&%Jensen%

Gauge%

Market(Price(Spreadsheet(

WECC%Market%Hubs%

Monthly(Hydro(Informa@on(

•%Genera>on%(MWh)%%

•%Water%release%(TAF)%

•%Power%Conversion%(MWh/AF)%

3rd(GTMax(Simula@on(

Baseline%Scenario%

ROD(Opera@ng(Criteria

•%Daily%Change%(cfs/day)%

•%Hourly%Ramp%Limits%(cfs/hr)%

•%Maximum%Flow%Limits%(cfs)%

•%Minimum%Flow%Limits%(cfs)%

Financial(Value(Calcula@ons(

Change%in%Glen%Canyon%Dam

%Hydropower%Value%Due%to

%Experiments%

BHBF

•%Water%Release%(cfs)%

•%Genera>on%(MWh)%

Fix(Flaming(Gorge(

Opera@ons(

Fix(All(Opera@ons(

Except(Glen(Canyon(

Monthly(Water(

Adjustments(

Dispatch(Guidelines

•%Load%following%

•%Weekend%releases%

Customer(Loads(

Hourly%Profiles%

All(Hourly(Opera@ons(

Except(Glen(Canyon(

Model Assumptions Matter 

Alternatives: Freezing All but Glen Results 

Optimize Economics or Realistic Operations
GTMax Model Result 

Allow Off-Peak Block Purchases for On-Peak Sales

These%Results%Are%Very%Different%from%Ones%that%Require%Strict%Load%Following%
No One Modeling Process Solves Every Problem 

Future Projections - Shortage Criteria Power Economics Modeling Process 

CRSS%Model%

Trace%Results%by%Month%%

•%Turbine%Release%(AF)%

•%Power%Conversion%%(kWh/cfs)%

•%Physical%Capability%(MW)%

GTMax%

Data%Processor%

Water%Release%Constraints

•%Daily%Change%(cfs/day)%

•%Hourly%Ramp%Limits%(cfs/hr)%

•%Maximum%Flow%Limits%(cfs)%

•%Minimum%Flow%Limits%(cfs)

Weekly%Constraints%%

•%Total%Genera>on%(MWh)%

•%HydroePlant%Opera>ng%Limits%

GTMax%

Dow%Jones%Spot%

Prices%($/MWh)%

AURORA%Model%

Spot%Prices%($/

MWh)%

Spot%Price%

Processor%

Representa>ve%

Spot%Price%%

Profile% •%Infla>on%Rate%(%/yr)%

•%Discount%Rate%(%/yr)%

•%Hourly%Hydro%Produc>on%(MWh)%

•%Hourly%Nominal%Spot%Price%($/MWh)%

•%Monthly%Constrained%Capability%(MW)%

•%Nominal%&%Real%Weekly%Value%($)%

•%Net%Present%Value%($)%

GTMax%

All%other%SLCA/IP%Plants% PRS%Spreadsheet

Customer%Power%Rates%
21)

GTMax-Lite Revenue Risk Assessment

No Action Alternative in 2020
Riverware**

Monthly*Trace*Results***

•*Total*Water*Release*(AF)*

•*Hydropower*plant*capacity*

•*Reservoir*Forebay*Eleva)on*(W)*

•*Power*Conversion**(kWh/cfs)*

GCD*Probability**

Distribu)on*Spreadsheet***

GCD*Opera)onal*Constraints*

•*Daily*Change*(cfs/day)*

•*Hourly*Ramp*Limits*(cfs/hr)*

•*Maximum*Flow*Limits*(cfs)*

•*Minimum*Flow*Limits*(cfs)

GTMax*(PreISchedule)***

Dow*Jones*

Spot*Prices* AURORA*Spot*

Prices*

Spot*Price*

Processor*

Representa>ve%

Spot%Price%Profiles%

•*Infla)on*Rate*(%/yr)*

•*Discount*Rate*(%/yr)*

Hourly*Water**

Release*Matrix***

Other*SLCA/IP*Hydropower*Plants

•*Median*hydropower*condi)ons*

•*Opera)on*rules*

•**Environmental*Constraints*

CRSP*Firm*Contract*Model***

Load*Scaling**

Algorithm***

Historical*CRSP Hourly*

Firm*Load*

Selected%GCD%

Hydrological%States%

Sediment**

Models*

Monthly*Water**

Realloca)on**

Model*(Alt*1,2,*&*3)*

BHBF%

No%

BHBF%

Hourly*Economic**

&*NPV*Calcula)ons*

Sediment**Models*

Hourly*Release* (No*Addi)onal*BHBF)*

Rou)ne*

Hourly*Release*

Rou)ne*

Spike*Flow*

Rules*

GTMaxIAHP*(Other*SLCA/IP)*

Run(Once(

Run(Once(

GCD*

Maintenance*

Reclama)on*

Western*&*Argonne*

Data*

Model/Rou)ne*

Seasonal*CROD**

Monthly*SHP**

Project*Use*Loads*

GTMaxIAHP*(Only*GCD)***

CRSP%Capacity,%%%

Energy,%MSR%

GCD%AHP%%%

Capacity,%Energy,%Min%

Hourly%Firm%%

CRSP%%Loads%

SSARR*

PO&MI59*

Run(Once(

*%Indicates%Scenario%Dependent%

**%Dependent%on%both%Scenario%&%Hydrology%

GCD*

Maintenance*

LTEP(Method
23)

Thank*you*for*your*aben)on*

Source:(BOR(