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Houston Import Evaluation Cross Texas Transmission & Garland Power & Light ERCOT RPG Meeting August 27 th , 2013. 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
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Houston Import EvaluationCross Texas Transmission & Garland Power & LightERCOT RPG Meeting August 27th, 2013
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
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
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 Singleton-Zenith 345-kV line for the contingency loss of Roans Prairie-Kuykendahl/ 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
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
GP&L/TMPA Affected Facilities – Existing N-H Corridor Estimated Congestion Costs, N-H Constraints, ERCOT LTS Effort Source: ERCOT DOE Long Term Study (ERCOT POI Site)
GP&L/TMPA Affected Facilities – Existing N-H Corridor Houston Import, Congested Elements, ERCOT LTS Effort
GP&L/TMPA Affected Facilities – Existing N-H Corridor 2015 & 2017 Projected Economic Constraints, ERCOT C&N Report 2012 (Source: ERCOT 2012 Constraints & Needs Report)
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
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
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
Transmission Options Studied (Source: CTT/GP&L Houston Import RPG Submission)
Preferred Options Preferred Options, Houston Import Study (Source: CTT/GP&L Houston Import RPG Submission)
Preferred Options ERCOT LTS Scenario 3, 2022 Economic Project Assessment
Preferred Options • 345kV Limestone – Gibbons Creek - Zenith • 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 ($121M) • Provide all the benefits stemming from Gibbons Creek – Zenith • Limestone provides access to significant generation in the North
Preferred Options • 345kV Gibbons Creek – Zenith • Provides close to 2000 MW of Houston import capability at significantly high MW/$M • Requires comparatively less upgrades on existing N-H corridor to achieve Houston import capability level • 345kV Gibbons Creek – Tomball • 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
Questions • Questions/Discussion