ERCOT Staff Facilitator Juan S. Santos Senior Consultant, System Planning Technical Operations WIND GENERATION STABILITY MODELING TASK FORCE UPDATE FOR ROS APRIL 9, 2002

MOTIVATION Large number of new wind plants in West Texas MW & Growing West Texas already is transmission limited Primary is stability limit Secondary is thermal limits Accurate and Appropriate models development is necessary to support transmission planning and operational studies. Model development does have a cost Share the costs More Wind Generation Development is likely !

GENERATOR OUTPUT AND WIND SPEED

TYPES OF STABILITY STUDIES

MODELING REQUIREMENTS Control Block Diagrams Transmission interconnection point “aggregated” wind farm model. Incorporated in the PTI PSSE program and model library. –For use by ERCOT Staff, TSP’s & Stakeholders Validation that the numerical model responds the same as the “real world”. –Monitoring & Testing Flexible Model with ability to incorporate “local” time and seasonal factors –Stochastic Nature of Wind Account for both Real and Reactive power under steady state and dynamic studies Translation into PTI – Source Code

ADDITIONAL MODELING REQUIREMENTS Electro-mechanical interaction between turbines in “wind farms” that are near and with different set points excited by disturbances in power grid? –Soft shafts and different control set points pitch control, variable speed, voltage control etc… Effects of weak system (low X/R ratio) Periodic pulsations due to wind shear, wind speed and turbulence Model voltage, transient and subtransient stability phenomenon

COST SHARING Invoices Sent Out 02/26/02 COMPANYSITE NAME SIZE (MW) % OF COST RECD Cielo WindCapital Hill1008.9% Trent Wind Farm, LPTrent Wind Farm % Indian Mesa Power Partners LPEnron Indian Mesa I & II % FPL Energy Pecos WindWoodward Mt. Wind Ranch % FPL Energy Upton Wind IKing Mt. Wind Ranch % FPL Energy Upton Wind IIKing Mt. Wind Ranch % FPL Energy Upton Wind IIIKing Mt. Wind Ranch % FPL Energy Upton Wind IVKing Mt. Wind Ranch % NWP Indian Mesa Wind Farm, LPIndian Mesa Wind Farm % AEP-WTUFort Davis 160.5% FPL EnergyMesa Wind 1 (SW Mesa) % Delaware Mountain Wind Farm, LPDelaware Mountain Wind Farm % New World Texas Renewable Energy Big Spring Wind power Facility& Westex I Wind power % Wind Power Partners, LPKunitz %

VERY ROUGH COST ESTIMATE –Model Development $125,000 to $200,000 –Travel/Meetings $10, 000 to $20,000 –Validation /Testing $50,000 to $80,000 (?) –Data Research $20,000 to $30,000 (?) –Monitoring Equipment $20,000 to $30,000 (?) –Totals estimated at $225,000 to $360,000

DRAFT TIME TABLE