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Assessing the Impact of Distributed Wind Generation

This presentation by Tom McDermott, Ph.D., explores the impact of distributed wind generation technologies and their economic implications on energy production. Funded by multiple organizations, including APPA and NRECA, the discussion includes web-based tools for engineering and flicker evaluation. Key topics include capacity factors, tax incentives like the Production Tax Credit (PTC), and Clean Renewable Energy Bonds (CREBs). The presentation also highlights flicker causes related to wind turbines and provides case studies illustrating successful implementations.

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Assessing the Impact of Distributed Wind Generation

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  1. Assessing the Impact ofDistributed Wind Generation Tom McDermott, Ph.D., P.E. Senior Consulting Engineer www.enernex.com APPA E&O Tech. Conf., April 16, 2007

  2. UWIG’s DistWind Project • Funded by APPA (DEED), NRECA (CRN), EPRI, California Energy Commission, others • Web-based Screening Software Tools • Flicker evaluation • Economics • Web-based Engineering Software Tools • Voltage control • Overcurrent protection • Case studies, application guides, measurements UWIG DistWind

  3. Distributed Wind Economics • Capacity Factor: Determines Energy Production • Look at Wind as an Energy Source, not Capacity • Tax Incentives: Enhance the cash flow • Production Tax Credit (PTC) • Clean Renewable Energy Bonds (CREB) • Plus the usual considerations • Debt and Equity financing • Insurance, O&M, tax requirements • Evaluate by net present value (NPV), internal rate of return (IRR), payback period, etc. UWIG DistWind

  4. Production Tax Credit (PTC) • Energy Policy Act of 1992 – 1.5 ¢/kWhr • Has been extended five times • Adjusted for inflation – currently 1.9 ¢/kWhr • Lasts for 10 years • Must pay federal income taxes in order to use the PTC • Equivalent REPI for non-taxable entity, under-funded • Tax Relief and Health Care Act of 2006 • Extended PTC to December 31, 2008 UWIG DistWind

  5. PTC In WindFinance UWIG DistWind

  6. Clean Renewable Energy Bonds • A “tax credit bond” for municipals, cooperatives, tribal governments, others who can’t use PTC • Issuer pays no interest; instead the bondholder receives a Federal tax credit • Energy Tax Incentives Act of 2005 authorized $800M for CREBs issued in 2006 and 2007 • 786 Applications Filed by April 26, 2006 • 610 Approved; 112 for Wind and 434 for Solar • Tax Relief and Health Care Act of 2006 • Extended CREB another $400M (Total $1.2B) • Extended CREB to December 31, 2008 UWIG DistWind

  7. CREB In WindFinance UWIG DistWind

  8. Capacity Factor • Energy = CF * (8760 hrs/yr) * (kW rating) • Wind speeds are variable • Power depends on speed3 • Actual site measurements are best • Electrical power output depends on the turbine and interface design • Complicated function of aerodynamics and controls • Controls are generally considered proprietary UWIG DistWind

  9. http://www.nrel.gov/wind/wind_map.html UWIG DistWind

  10. Economics: Capacity Factor Module • Wind Data: • Actual Measured Distribution • Measured Average Annual Speed • Average Annual Speed from a Map • Power Curve: • Specific • From Library • Uploaded • Generic UWIG DistWind

  11. What is Flicker? • Short-term Voltage Fluctuations that may cause perceptible, or objectionable, lighting flicker Flicker Period [s] UWIG DistWind

  12. What Causes Flicker? • Motor starting and load variations • Arc furnaces and welders • Wind turbines • Variations in wind speed • Blade pitching • Tower shadowing • Wind shear or gradient • Start and stop UWIG DistWind

  13. Variations in Wind Speed • Inertia and controls help soften the impact UWIG DistWind

  14. Effect of Blade Pitching • Pitch control affects power curve, but doesn’t respond instantly • Stall-regulated blades more closely maintain rated output UWIG DistWind

  15. Tower Shadowing • Sometimes called 3-P Effect, 0.5 – 1.5 Hz UWIG DistWind

  16. Wind Shear or Gradient • Blade torque varies with position because the wind speed varies with height UWIG DistWind

  17. Turbine Start and Stop • Similar to motor starting, but advanced controls and interface may soften the impact UWIG DistWind

  18. Old-Style GE Curve • Rectangular Voltage Change, 50% Duty Cycle UWIG DistWind

  19. Measurement is Complicated! UWIG DistWind

  20. Flicker Evaluation • IEEE Std. 1453-2004 follows the IEC approach • If PST = 1, 50% of the people will complain • Measured every 10 minutes (144 times per day) • Planning Level: PST > 0.9 only 1% of the time • Flicker varies along the feeder UWIG DistWind

  21. Flicker Calculator • Quick Answers • On Web Site: • NEG Micon • Nordex • Vestas • GE • Requested: • Mitsubishi • Clipper • others UWIG DistWind

  22. Estimating Short-Circuit Strength • Same Data as Used for Harmonic Studies • Estimate the System Impedance at Point of Common Coupling (PCC) at Primary Voltage UWIG DistWind

  23. Feeder Simulator for Engineering • Imports MultiSpeak • Shortcuts • Sample Files • On-line Help UWIG DistWind

  24. Voltage Control Outputs Checks ANSI C84.1 UWIG DistWind

  25. Overcurrent Protection Outputs CB1 should not lock open UWIG DistWind

  26. Case Study #1: TVA Buffalo Mountain • Three Vestas V47 WTGs, Total 2 MW • 13.2-kV Feeder, 9.6 miles long, 69-kV Source • No Voltage Control Problems • Removed the High-Speed Reclose Operation • No Reduction of Reach or Sympathetic Trip UWIG DistWind

  27. Case Study #2: PGE Hunter’s Point • 12-kV Feeder, 6.4 miles long • One GE 1.5xle Turbine, 1500 kW • Use high-efficiency turbine, greater hub height, and higher wind shear factor than in CEC study • No Flicker Problems or Limits • Voltage Control and Overcurrent Protection limit the total WTG to 7500 kW UWIG DistWind

  28. Case Study #3: Illinois Rural Electric • One NM82 Vestas/NEG Micon Turbine, 1.65 MW • Operating since May 2005 • 12.47-kV Feeder, 34.5-kV Transmission Source • IREC Filled out the Feeder Simulator Data Sheet • Overvoltage and Undervoltage Trip Functions are Essential • Evaluated Use of CREB (actual project had 46% grant funding, before CREB available) • Two Turbines → Flicker and Tap Changer Issues UWIG DistWind

  29. East River Coop, Chamberlain, SD • Two Nordex N60/1300 Turbines • 69/12.47-kV Substation Transformer, 3750 kVA • 4/0 Cable, 1/3 Concentric Neutral, 12 kft from Substation • On a Dedicated Feeder, but Still had Flicker Complaints • Solutions implemented by Basin Electric: • Turbine Vendor adjusted Controls • Dynamic VAR Compensation • Dedicated Transformer (2500 kVA Mobile) UWIG DistWind

  30. Members-Only Index Page(www.uwig.org/distwind) DEED members please contact Michele Ghosh Suddleson for password; msuddleson@APPAnet.org Demos at the UWIG Booth in Vendor Showcase UWIG DistWind

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