1

• DRAFT
• RMATS 2008 Base Case
• (To be presented at the RMATS Stakeholders
  Meeting)

March 17, 2004
2
Overview

• Modeling Approach
• Purpose Scope Base Case
• Key Assumptions
• Base Case Results

3
Modeling Approach

• Modeled with ABB Market Simulator
• Production cost model
• West-wide scope with a particular focus on the
  RMATS region
• Detailed transmission representation
• Calculates nodal / bus prices (LMPs)
• Hourly resolution
• LP dispatch optimization is based on
• Treatment of hydro and wind generation
• Single test year 2008

4
LMPs Marginal Costs at the Nodal Bus Level

• The cost of delivering the next 1 MW of power to
  a particular location, or the savings from
  reducing load by 1 MW at that location (sometimes
  called shadow price)
• In concept, transmission congestion (bottlenecks)
  an losses cause differences in marginal prices at
  the nodal/bus level
• LMPs are calculated separately for loads and
  generation
• LMPs tend to decrease as relatively low cost
  resources are added
• High wind capacity sensitivity is an example
• Targeted transmission investments
  levelize/stabilize marginal prices because
  congestion is relieved but the investment cost
  may outweigh the benefit

5
Modeling Limitations

• Modeling assumes a single, seamless west-wide
  market with no rate or loss pancaking
• LP optimizes dispatch on a west-wide basis
  (perfect knowledge)
• Not modeled
• Must-run generation
• Unit commitment
• Transmission wheeling and loss charges
• Generator forced outages
• Contractual / tariff constraints
• Bid behavior
• Sub-hourly operations
• Actual heat rate curves- approximate only

6
Implications of Modeling Approach

• Tends to make fuller, more optimal use of
  transmission than operations currently allow
• Analogous to a seamless, single RTO world
• Tends to mask the tariff and contractual
  constraints of today
• Makes wind appear more economic because fewer
  constraints lead to greater dispatch
• Fifteen percent planning margin used may be
  conservative
• Margin is calculated off nameplate
• Covers generator forced outages and operating
  reserves that ABB MS does not model

7
Base Case Objectives

• Focus on congestion and congestion costs
• Assess the current system
• Include existing system, plus new, viable
  investment already in progress
• Identify incidence and duration of congestion
• Estimate the resulting congestion costs
• Include several load, gas price, and hydro
  sensitivities
• Review plant performance
• Illuminate opportunities for cost-effective
  projects
• Estimate the incremental value of expansion on
  congested paths

Base Case Runs
2008 Load 2008 Load w/ additional wind High Load
4 Gas X X X
5 Gas X X X
2013 loads applied to 2008 resources and
transmission
8

• Key Assumptions

9
Key Assumption Summary
http//psc.state.wy.us/htdocs/subregional/home.htm

10
System Balloon Diagram
11
Loads 2008 Base Case Based on WECC LR
Forecast issued in 2003, with updates for Rocky
Mountain States
Annual GWh with Coincidental Summer Winter
Peaks (GW)
Mexico - CFE
Summer 2.5 Winter 2.2
NWPP-Canada
Summer 16.6 Winter 20.3
14,425
California
130,743
Summer 58.4 Winter 44.8
NWPP-US
165,719
309,324
Summer 24.1 Winter 30.8
156,763
143,595
AZ, NM S. NV
Rocky Mt. States
Summer 24.6 Winter 21.4
Summer 31.2 Winter 24.7
Load 920,569 GWh Summer Peak 157 GW
12
Resource Additions- 2008 Base Case
Incremental Additions
2008 Rocky Mountain Area Total Resources (MW)
Total Capacity 29,121 MW

• All plants in service by 2006
• Does not include additional wind capacity of
  1750 MW

13
Hydro, DSM, Wind 2008 Base Case

• Hydro
• Hydro generation is simulated for median water
  conditions
• Used SSG-WI hourly shapes for Canada and the
  Northwest
• DSM
• For the 2008 Base Case, efficiency and DSM
  programs are decremented against loads in the
  WECC forecast
• Wind
• High wind sensitivity - added 1742 MW nameplate
  to the 508 MW in the base case, bringing the
  total to 2250 MW of wind in the Rocky Mountain
  Area
• Did not consider transmission impacts other than
  on monitored interfaces (feasibility may require
  significant transmission additions)

14

• Base Case Results

15
Base Case Observations

• The top 5 congested paths in the Rocky Mountain
  sub-region are also export-related paths
• Idaho to Montana
• TOT 2C
• Bridger West
• IPP DC
• TOT 3

16
LMP PricesAverage Annual
Load LMP Generation LMP
4 Gas/ 2008 Load 4 Gas/ 2008 Load
4 Gas/ High Wind 4 Gas/ High Wind
4 Gas/ High Load 4 Gas/ High Load
5 Gas/ 2008 Load 5 Gas/ 2008 Load
17
January 2008 Monthly Average LMP4 Gas
18
June 2008 Monthly Average LMP4 Gas
Congested Paths

• Northwest to Canada

Idaho to Montana
Bridger West
COI
Significant N-S Congestion
19
June 12, 2008 hr 064 Gas
Significant S-N Congestion
20
June 12, 2008 hr 124 Gas
Significant N-S Congestion
21
June 12, 2008 hr 154 Gas
Significant N-S Congestion
22
Key RM Transmission Constraints4 gas, 2008
loads, base wind
Interface Location Direction Forward limit (MW) Reverse limit (MW) Opportunity cost of next MW hours congested
Idaho to Montana E. Idaho to W. Montana S N 337 337 28,324 5
TOT 2C S. Utah to S.E. Nevada N S 300 300 11,706 15
Bridger West S.W. Wyoming to S.E. Idaho to Northwest E W 2,200 N/A 10,749 19
IPP DC C. Utah to S. California NE SW 1,920 300 10,141 72
TOT 3 S.E. Wyoming to N.E. Colorado N S 1,424 N/A 5,649 8
SW Wyoming to Bonanza S.W. Wyoming to E. Utah N S 200 200 2,590 3
4 Gas- H load- 26,325 12
23
Key Transmission Constraints 4 gas, 2008
loads, base case wind
Top Congested Paths
24
Western Interconnect Impact for 20084 gas, 2008
loads, high wind
Interface limitation Annual VOM (000) Delta from Base Annual VOM (000) Annual average LMP Annual average LMP Delta from base annual average LMP Delta from base annual average LMP
Interface limitation Annual VOM (000) Delta from Base Annual VOM (000) Load (/MW) Generator (/MW) Load (/MW) Generator (/MW)
Base Case 13,683,646 37.97 37.24
All interfaces unconstrained 13,562,347 (121,299) 38.09 38.08 .12 .84
Only internal RM interfaces are unconstrained 13,642,615 (41,031) 38.01 37.41 .04 .17
Only top 5 congested interfaces are unconstrained 13,691,688 (8,042) 38.03 37.41 .06 .17
25
Evaluation of PotentialSolutions
26
Idaho to Montana (4 gas, 2008 loads, base case
wind)Potential solution

• Potential Solution
• Added phase shifter at Peterson Flats to Amps
• Results
• System-wide VOM cost decreases by 5 million
  in 2008
• Decreases binding congestion to 1 from 5 of the
  time
• Path loading increases by 1,673 MWh

1,102,119 MWh
BEFORE
5
S
N
1,103,792 MWh
AFTER
1
S
N
27
IPP DC (4 gas, 2008 loads, base case
wind)Potential solution

• Potential Solution
• Increased line rating by 500 MW NE to SW (Forward
  limit 2400 MW)
• Results
• System wide VOM cost decreases by 4.6 million
• Line loading increases by 2,863,577 MWh
• Decreases binding congestion to 57 from 72 of
  the time

BEFORE
72
14,952,799 MWh
NE
SW
57
17,816,376 MWh
AFTER
NE
SW
28
SW Wyoming to Bonanza (4 gas, 2008 loads, base
case wind)Potential solution

• Potential Solution
• Increased line rating by 100 MW (increase line
  limit to 300 MW from 200MW) this can be
  accomplished by adding a transformer and possibly
  line compensation.
• Results
• System wide cost decreases by 4.3 million
  hydro model does not allow hydro redispatch.
• Line loading increases by 7,170 MWh
• Alleviates binding congestion, which now occur 3
  of the time

909,604 MWh
BEFORE
3
N
S
AFTER
902,434 MWh
N
S