Houston Import Evaluation
Cross Texas Transmission & Garland Power & Light
ERCOT RPG Meeting
August 27th, 2013
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Agenda
 Houston Import Needs Discussion
 GP&L/TMPA Affected Facilities – Existing N-H
corridor
 Impact of N-H import/solution on Gibbons Creek
 Additional Considerations
 Transmission Options Studied
 Preferred Options
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Houston Import Needs Discussion
• Base case reliability need observed for Houston import for
2018
 Thermal overloads under N-1 + G-1 conditions observed to be key
drivers for the reliability need
 N-H transfer levels modeled at 3100 MW for the 2018 study case
• Houston Import reliability needs and long-term
effectiveness of proposed solutions sensitive to the
following
 N-H transfer levels
 Generation availability within Houston and along the N-H import path
• Long term Houston load deliverability may require
significant re-conductor and/or upgrades of existing N-H
corridors
 Important consideration when evaluating feasibility of import options
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GP&L/TMPA Affected Facilities – Existing N-H Corridor
• Significant history of anticipated congestion on existing N-H
corridors across various ERCOT Houston Import study
efforts
– ERCOT Houston Import Study Update (April 2010) – “2014
benchmark case showed heavy congestion on SingletonZenith 345-kV line for the contingency loss of Roans PrairieKuykendahl/ Singleton-Tomball 345-kV double circuit.
Congestion also observed on Jewett-Singleton and Twin
Oak-Jack Creek 345-kV lines”
– ERCOT 2012 Long Term Study (LTS) – Scenarios of Interest
from Houston Import standpoint
– Scenario #2: Base with All Tech and Retirements
(retirement of legacy natural gas-fired generators)
– Scenario #3: Base with All Tech and Incremental Wind
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GP&L/TMPA Affected Facilities – Existing N-H Corridor
• Significant history of anticipated congestion on existing N-H
corridors across various ERCOT Houston Import study
efforts (Contd.)
– ERCOT 2012 Long Term Study (LTS) – Scenarios of Interest
from Houston Import standpoint
– Scenario #5-a: Drought Scenario
– Summer capabilities of existing water – consuming
resources de-rated
– Increased peak load
– Scenario #7: BAU – Hi Natural Gas
– Characterized by a high natural gas price ($9.55 by
2016, $13.7 by 2022)
– Resources retire in 2018 and 2022 for competitive
reasons
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GP&L/TMPA Affected Facilities – Existing N-H Corridor
Congested Element
ERCOT LTS Scenario Estimated Congestion Rent Total Congestion N-H Corridor
Jewett - Singleton
$21,822,635
Singleton - Zenith
n/a
Scenario 2
$67,961,598
Gibbons Creek - Twin Oak
$18,477,219
Gibbons Creek - Singleton
$27,661,744
Jewett - Singleton
$8,136,557
Singleton - Zenith
$98,370,285
Scenario 3
$162,867,088
Gibbons Creek - Twin Oak
$18,171,816
Gibbons Creek - Singleton
$38,188,430
Jewett - Singleton
$48,989,777
Singleton - Zenith
n/a
Scenario 5-a
$166,595,243
Gibbons Creek - Twin Oak
$64,824,376
Gibbons Creek - Singleton
$52,781,089
Jewett - Singleton
$128,650,263
Singleton - Zenith
$492,051,104
Scenario 7
$778,484,305
Gibbons Creek - Twin Oak
$71,098,392
Gibbons Creek - Singleton
$86,684,546
Estimated Congestion Costs, N-H Constraints, ERCOT LTS Effort
Source: ERCOT DOE Long Term Study (ERCOT POI Site)
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GP&L/TMPA Affected Facilities – Existing N-H Corridor
Houston Import, Congested Elements, ERCOT LTS Effort
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GP&L/TMPA Affected Facilities – Existing N-H Corridor
Medium Impact
High Impact
2015 & 2017 Projected Economic Constraints, ERCOT C&N Report 2012
(Source: ERCOT 2012 Constraints & Needs Report)
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GP&L/TMPA Affected Facilities – Existing N-H Corridor
• All ERCOT Houston Import evaluations indicative of
significant anticipated congestion on existing N-H corridor
• Two key GP&L/TMPA facilities part of the congestion
constraints
 345kV Gibbons Creek – Twin Oak
 345kV Gibbons Creek - Singleton
• Avoiding congestion (and overloads) on existing N-H
corridors will provide significant cost savings to Houston
region
 Provides significant economic benefits to any Houston reliability
project
 Prevent the need to take additional outages to re-conductor 345kV
lines along an already congested N-H corridor
• Critical aspect to be taken into account when evaluating
import project options
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Houston Import – Impact on TMPA/GP&L Facilities
• Need to alleviate congestion/potential overloads on
TMPA/GP&L transmission facilities in existing N-H corridor
as part of Houston Import
• Need to ensure that potential Houston import solutions
divert enough power from existing N-H corridors
 Looping N-H projects via intermediate stations
 South – Houston projects with large enough transfer capability to
offset flows from the north
 Direct solutions with series compensation
• Transmission solutions looped through existing TMPA
facilities may exacerbate over-voltage issues under light
load conditions
 TMPA RPG approved project for 130-150 MVAR reactor on 345kV
Gibbons Creek expected to address this issue
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Additional Considerations
• Recent history of Gibbons Creek unit being requested to
provide VAR support during high N-H transfer levels (at the
cost of active power to TMPA member cities)
 Gibbons Creek unit exempt from PRR830 requirements
 Gibbons location significantly strong with little ability of external
reactive equipment impacting voltage downstream
 Optimal approach would be to reduce impedance between Gibbons &
Houston thereby improving voltage conditions in the region
• Ability to reduce the “N-1” impact created by the proposed
solution itself
 Important to ensure that the proposed solution does not become the
single largest contingency for Houston import
 Utilize existing infrastructure and expansion capability to reduce the
reliability impact for the outage of the proposed option
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Transmission Options Studied
(Source: CTT/GP&L Houston Import RPG Submission)
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Preferred Options
Preferred Options, Houston Import Study
(Source: CTT/GP&L Houston Import RPG Submission)
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Preferred Options
Capital Cost
Reliability benefit
Adjusted for
of test project
Reliability Benefit
($M)
($M)
Production
Cost Savings
($M)
1/6 of
Meet ERCOT
1/6 of Capital Adjusted
Economic
Cost ($M) Capital Cost
Criteria ?
($M)
Test Project
2022 capital
cost ($M)
Limestone-Gibbons CreekZenith
268.4
120.6
147.8
36.6
44.7
24.6
Yes
Watermill-Big Brown
208.2
23.1
185.1
0.1
34.7
30.9
No
Lake Creek – Navarro
104.1
42.1
62.0
1.7
17.3
10.3
No
Lake Creek – Watermill
297.4
19.0
278.4
0.4
49.6
46.4
No
Clear Spring - Hill County
104.1
0.0
104.1
4.1
17.4
17.4
No
Hays - Kendall second 345kV
circuit
41.8
0.0
41.8
3.2
7.0
7.0
No
Sandow - Garfield
133.8
0.0
133.8
4.0
22.3
22.3
No
ERCOT LTS Scenario 3, 2022 Economic Project Assessment
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Preferred Options
• 345kV Limestone – Gibbons Creek - Zenith
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
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
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Most optimal performing option in terms of incremental Houston import
capability vs project cost (across options providing greater than 2500 MW
Houston import capability)
Houston import capability observed to be as high as 3000 MW with MLSE
upgrades on TMPA N-H facilities
Virtually no need to upgrade existing N-H corridor to achieve import capability
Flexibility to achieve close to 3500 MW Houston import capability with upgrades
on N-H corridor in long term
Deemed economic via the ERCOT LTS Study for 2022 (S3) with significant
reliability benefits ($121M)
Provide all the benefits stemming from Gibbons Creek – Zenith
Limestone provides access to significant generation in the North
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Preferred Options
• 345kV Gibbons Creek – Zenith


Provides close to 2000 MW of Houston import capability at significantly high
MW/$M
Requires comparatively less upgrades on existing N-H corridor to achieve
Houston import capability level
• 345kV Gibbons Creek – Tomball
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
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Provides close to 2200 MW of Houston import capability at significantly high
MW/$M
May require reactive equipment enforcements in the long term to result in
Houston import levels greater than 3000 MW
Requires comparatively less upgrades on existing N-H corridor to achieve
Houston import capability level
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Questions
Questions/Discussion
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