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CREZ Shunt Switching

CREZ Shunt Switching. John Adams Principal Engineer. Outline. Review of Section 14 of the ABB CREZ Reactive Study Purpose = check breaker duty cycles and confirm bank sizes Full-year 8760 hour chronological analysis Intra-hour chronological analysis for maximum variability. Methodology.

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CREZ Shunt Switching

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  1. CREZ Shunt Switching John Adams Principal Engineer Regional Planning Group

  2. Outline • Review of Section 14 of the ABB CREZ Reactive Study • Purpose = check breaker duty cycles and confirm bank sizes • Full-year 8760 hour chronological analysis • Intra-hour chronological analysis for maximum variability RPG

  3. Methodology • Based on 2009 operating data of existing windfarms in CREZ areas • Scaled up from 1269 MW nameplate (representative windfarms) to 16092 MW nameplate, “Initial Build” level, per area profile • Variation in wind generation offset by non-wind generation in the east • No contingencies applied RPG

  4. Reactive Assumptions • Var limits of future CREZ windfarms were reduced to preserve reactive capabilities for disturbances • All switchable shunts were enabled • CREZ switchable shunts were set to control their own bus voltages, +/- 2% except where the TSPs requested different ranges • CREZ SVCs not modeled, also to preserve reactive capabilities for disturbances RPG

  5. Full-Year Results • Proposed reactor banks sizes were reduced at Hereford and at Edison substations to reduce the bus voltage change per switching operation • Total number of switch operations per CREZ reactive bank for the year varied from very few to 700. RPG

  6. Full-Year Results • Analysis repeated with the Oklaunion plant brought on-line • Drastically reduced the total number of switch operations per bank at Hereford, Oklaunion, and Riley • Analysis repeated for wind dispatch biased towards new CREZ generators and away from existing windfarms • Almost no change from base analysis RPG

  7. Intra-hour Results, Sample Hour RPG

  8. Intra-hour Results, Wind Ramp Down • On April 30, 2009, from 21:30 to 22:30 total ERCOT load decreased 3131 MW, about 8% • From 21:47 to 22:16, total ERCOT wind generation decreased 2437 MW, about 53% • The simulation for this sample hour produced 25 individual switch operations RPG

  9. Intra-Hour Results, Wind Ramp Down • Riley, 5 switch operations from +158.2 to 0 to -50 to -100 to -150 to -200 Mvar • Hereford, 3 switch operations from -100 to -150 to -200 to -150 Mvar • Clear Crossing, 2 switch operations from -200 to -250 to -300 Mvar RPG

  10. Intra-Hour Results, Wind Ramp Down • Red Creek, 2 switch operations from 0 to -100 to 0 Mvar • Brown, 2 switch operations from +100 to 0 to -100 Mvar • Edison1 and Edison2, 2 switch operations each from 0 to -50 to -100 Mvar for a total of four operations RPG

  11. Intra-Hour Results, Wind Ramp Down • Single switch operation of -100 Mvar at Tonkawas • Single switch operations of -50 Mvar at Nazareth, Edith Clarke, Tesla, Tonkawas North, and Gillespie • Single switch operation of -30 Mvar at Oklaunion RPG

  12. Conclusion • TSPs have the information they need to specify the breakers they are ordering. • Coordination of the operations of nearby shunts will be necessary to prevent hunting. • ERCOT will coordinate a TSP operator meeting to develop voltage control procedures for the CREZ regions. RPG

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