Denton Municipal Electric

Distribution Modeling Considerations

DREAM Task Force

Lance Cunningham, Ph.D., PENovember 2015

Frisco, TX

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Transmission Modeling

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Transmission Modeling

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Distribution Substation

5This document and that is confidential, commercially-sensitive, proprietary, and/or public power utility competitive and financial information in accordance with the provisions of Texas Government Code, Section 552.101, 552.104, 552.110 and/or 552.133, and may be protected from required public disclosure.

Load Serving Transformers

Distribution Circuits

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The distribut-ion system is much more complex.

FRISCO

Panther Creek

Roman Juarez

Bridges

Yellow might equal blue

Distribution Operations

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Pole top switches to balance circuits, back-feed or sectionalize for problems, etc.

Direction ….. ?

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• If the direction is to reflect all distributed resources back to their respective transmission buses, then all is done.

Direction ….. ?

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• If the direction is to model all distributed resources to a distribution bus AND to compute a “distribution based locational marginal price” …….

• Then the following modeling and operational parameters need to be overcome.

Distributed Resources modeled at the distribution level

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• How should an effective “Transmission Constraint Shadow Price Cap in SCED” be reflected to the distribution level? Existing N-1 Constraint Violation Caps

o 345 kV: $4,500/MWo 138 kV: $3,500/MWo 69 kV: $2,800/MWo <69 kV: $????

Distributed Resources modeled at the distribution level

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• How should the “Texas Two Step” locational market power test be applied at the distribution level?

• DERs modeled in ERCOT and receiving price signals from SCED should be subject to the Constraint Competitiveness Test in SCED (Protocols section 3.19) Non-Competitive Constraint Definition

A contingency and limiting Transmission Element pair or group of Transmission Elements associated with a GTC that is not determined to be a Competitive Constraint under the process defined in Section 3.19, Constraint Competitiveness Tests.

Current CIM and Planning Models

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CIM # of Switches

CIM # of breakers

CIM # of Settlement Points

33,928 13,293 599

Planning Case# of

Loads

Planning Case# of

Substations with Loads

Planning Case# of Buses with an Area Loads

5,649 3,164 3,782

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• Additional modeling considerations 1,000 DERs could result in 1,000 more modeling

points More SCADA points communicating with ERCOT Define distribution level contingencies? More automatic distribution switching schemes

o Automatic load rollover schemeso Automatic sectionalizing schemes

Outage scheduling of distribution level equipment Potentially longer SCED solution times

Distributed Resources modeled at the distribution level

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How much time AND money do we want to take for implementation?

• Generally, that is directly related to the level of complexity. How much personnel & equipment? Regulatory impacts? Staffing impacts?