November 12, 2010 Regional Planning Group Long-Term System Assessment Project Update Warren Lasher...

November 12, 2010

Regional Planning Group

Long-Term System AssessmentProject Update

Warren LasherManager, Long-Term Planning and Policy

Jonathan RosePlanning Engineer

2 Regional Planning GroupNovember 12, 2010

Purpose of the Long-Term Plan

To Inform Near-Term Planning with Potential Solutions that Meet Long-Range System Needs

• Intent is not to select new circuits to recommend

• Rather, the intent is to provide a selection of alternatives through scenario analysis that can be considered when developing solutions for near-term congestion or reliability needs

• To meet the NERC TPL Requirements for development of 10-year transmission plan


Specific Focus

The focus of this study is to look for:• Long-Lead-Time Projects – projects that may

require 5 or more years to bring on-line• Large Projects – short-term analyses tend to

focus on short-term solutions. A long-term perspective can indicate larger projects that both solve short-term issues but also meet long-term system needs more cost-effectively.

• This analysis will also provide implementation experience for some of the new tools and processes being developed for long-term planning.


Scope

• Study Years: 2020 – 2030• Load growth based on extrapolating current

ERCOT Long-Term Load Forecast• 2020 Peak Load: ~86,500 MW• 2030 Peak Load: ~102,000 MW

• All generation currently on-line (and expected to maintain operation) plus all units with signed IAs as of 9/1/2010

• Generation Expansion by Scenario• Report will be submitted to PUCT by end of 2010


Methodology

First Step: Simplify the ERCOT Transmission Network

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Motivation

• LTSA and DOE project are long-range studies.

• Due to uncertainties over a long time scale, different focus from near-term planning:– Scenario-based rather than typical year– Simplified model to highlight long-term

concerns while de-emphasizing issues better dealt with as they arise in the near-term.

November 12, 2010 Regional Planning Group

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Example: A 2030 Load-Flow Case

• Starting from the latest ERCOT five-year planning case

• Increase loads from 70+GW to ~102 GW• For initial testing purposes, add proxy generators to

fulfill load at existing sites and other obvious transmission locations

• Resulting case has 1400 N-1 overloads.• Why? Twenty years of transmission upgrades have

not been modeled.


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Example of 2030 Case

• Such a high number of overloads is prohibitively large to examine manually.

• Case simplification helps “filter” the overloads.

• Many overloads are on easily upgradable lines (generally short 69 kV). These aren’t the study’s focus, thus should be hidden from view.


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Case Simplification Steps

• Process Code written by Dave Matthews (AEP) and Jonathan Rose (ERCOT)

• Remove 69-kV network.• Remove 138-kV radial buses.• Remove 138-kV inline buses.• Raise rating of “short” rural lines.

– Definition of “short” is subject to tuning.


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Remove 69-kV Network

• Move all generators to nearest 138-kV bus.– POI bus is also moved, so bus number and name are

preserved for recognition.

• “Move loads”: Measure flow at the 138 / 69 kV autos and represent these flows by loads at the 138-kV buses.

• Remove 69-kV network.


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Remove Radials and Inlines

• Move load and switched shunts to neighboring bus.

• Three-winding transformers with a radial leg are converted to two-winding transformers. Radial load and switched shunt moved to high side.


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After Simplification

• Bus count reduced 6000 2000 (approx)• Line count reduced 6000 2000 (approx)• Flows on 138-kV and 345-kV bulk

transmission network mostly unchanged.• Example simplified system will be posted on

the Planning and Operations web-site



Methodology

Next Steps:• Generation Expansion Analysis

– Scenarios being evaluated:• Business as Usual• Coal Generation Expansion• Gas Generation Expansion• High Renewables

• Evaluate transmission projects that meet system needs


Summary

• Study focus is on identification of long-lead-time projects through scenario analysis that can be considered when developing solutions for near-term congestion or reliability needs

• Designed to meet the NERC TPL Requirements for development of 10-year transmission plan

• This analysis will provide implementation experience for some of the new tools and processes being developed for long-term planning.


Questions?

November 12, 2010 Regional Planning Group Long-Term System Assessment Project Update Warren Lasher...

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