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Harnessing high altitude wind power

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Harnessing high altitude wind power

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Harnessing high altitude wind power

  1. 1. HARNESSING HIGH-ALTITUDE WIND POWER Date;19/09/2012 1
  2. 2. . INTRODUCTION MAJOR JET STREAMS - BOTH HEMISPHERES  Sub-Tropical Jet  Polar Front Jet “These enormous energy streams are formed by the combination of falling of the tropical region’s sunlight and Earth’s rotation. This wind resource is invariably available wherever the sun shines and the Earth rotates.” 2
  3. 3. METHODS TO HARNESS HIGH ALTITUDE WINDS  Tethered balloons  Tethered fixed-winged craft  Tether climbing  Descending kites  Rotorcraft 3
  4. 4. UPPER ATMOSPHERIC WINDS  Highest power density for a large renewable energy resource  Total power dissipated =10 W  Power densities >10 kW/m  No adverse environmental consequences. 4 15 2
  5. 5. DESCRIPTION AND ELECTRICAL SYSTEM DETAILS TETHERED CRAFT Four identical rotors mounted in an airframe. TETHERS “single, composite ,electromechanical insulated aluminum conductors of high strength fiber.” Bring power to ground Wound with strong Kelvar family cords. Conductor weight is a critical compromise between power loss and heat generation. Tether transmission voltages is15 kV and higher 5
  6. 6.  Electrical losses b/w tethers & Converted power’s insertion into the commercial grid ≈ 20%.  power transmission ; 4 and 8 km  Rated capacity ; 3–30 MW.  Location much closer to demand load centers. 6
  7. 7. . FOUR-ROTOR ASSEMBLY Four identical rotors  Two forward and two afterward  The plan-form of the rotor centerlines is approximately square  . Adjacent rotors rotate in opposite directions.  Diagonally opposite rotors rotate in the same direction “When operating as an electrical power source rotors are inclined at an adjustable, controllable angle of up to 50◦ to the oncoming wind.” 7
  8. 8. DETAILS OF A 240 KW DEMONSTRATION CRAFT  Sky Wind Power Corporation - 240 kW 8
  9. 9. ROTORS  Connected to four separate gearboxes, -drive four motor/generator units supplied by AC propulsion  High armature speed for satisfactory power-to-weight ratio  Electrically linked for constant rotor speeds  Armature speeds are 24000r/min  Weight of the craft is estimated at around 1140 lb (520 kg)  Four, two bladed - paired counter-rotations  10.7 m in diameter with solidity of 5%  Collective pitch control via electric actuators  Designed for operations up to 15000 ft (4600 m) 9
  10. 10. ELECTROMECHANICAL TETHER  240 kW at a voltage of 15 kV  The electrical transmission efficiency is 90%  Two insulated aluminum conductors embedding a Vectron fiber composite  Specific weight ; 115 kg/km  The electrical ground facility is configured for a dc supply to and from the platform  The motor/generators are series connected 10
  11. 11. CRAFT .  Withstand a wind of 35 m/s at 15 000 ft (4600 m)  The craft’s rated output  Wind speed 18.4m/s  Altitude of 15 000 ft (4600 m) .  Power consumption 15 000 ft (4600 m)=75kW Rotor speeds = 130–300 r/min 11
  12. 12. THE HK DESIGN  The surface of HK -an array of small units 12
  13. 13. THE HK DESIGN  Each unit -four rotors and two generator  Conductive tether  Anchors the kite to the ground station  Transmission of generated electrical power  Drives a ground-based generator. 13
  14. 14.  Four savonious style rotors (SSR) in a frame  Adjacent savonious rotors rotate in opposite direction.  To minimize the turbulence interaction and air friction between rotors  The contra-rotor generators  Have two rotors,  Need two prime movers to rotate  ROTOR  opposite direction  Generator  lower weight  No brush 14
  15. 15. OPERATING MODES OF HK DESIGN  Blocked mode:  Rotor are blocked in vertical position respect to incoming wind,  Drag coefficient = maximum value.  Rotating Mode:  Free rotation of rotors in this mode,  Drag coefficient of unit =minimum value. 15
  16. 16. 16 GENERATORS  Permanent magnet,  Produce direct current  Can be easily connected in parallel or series configurations.  Diode , -avoid reverse flowing of current into the generators.  The generators in each unit are paralleled together,
  17. 17. FLIGHT CONTROL USING GPS AND GYRO DATA  Ideal way to provide the reference data for control.  Error sources  effects through the atmosphere,  satellite orbit and timing errors,  GPS receiver noise  signal reflection (multipath). 17
  18. 18.  Relationship between the achievable GPS-derived heading and pitch accuracy and antenna separation 18
  19. 19. AERODYNAMIC PERFORMANCE  power output Vs αc(constant tip speed ratio μ.) 19  preferred generating conditions C Coefficient of power Control axis angle V Velocity wind Tip speed ratio Ω Rotor speed  power coefficient of around 0.4  control axis ◦ of about 50  tip speed ratio of 0.075.
  20. 20. AERODYNAMIC PERFORMANCE 20
  21. 21. AERODYNAMIC PERFORMANCE Autorotation conditions:  conditions when wind speed is insufficient to support the craft and its tether.  system is on the point of collapse.  minimum wind speed to stay aloft occurs when the craft nose-up attitude is around 24  corresponding tip speed ratio of 0.10  minimum wind speed for autorotation is around 10 m/s-(at 4600m) 21
  22. 22. ENERGY STORAGE ISSUES  Pumped water storage  Compressed air energy storage (CAES)  Hydrogen. 22
  23. 23. COST AND PERFORMANCE PROJECTIONS AT THE LARGE SCALE SCALABILITY CONSIDERATIONS  scalable in size and output- from small prototype configurations of less than 240 kW, ( 3–30 MW per craft.)  Larger sizes are more economical  utilize more than four rotors to maintain economy and manageability of materials. 23
  24. 24. PROJECTED COE  (AOE) = (LLC)+(O&M),+ (LRC).  O&M =$82 000 per year estimate for a 3.4MW  FEG, multiplied by 29.4 FEGs/100 MW plant.  Replacement cost = 80% of the initial capital cost. AOE Annual operating expences LLC Land lease cost O&M Operation and maintance LRC Levalised replacement cost FCR Fixed charge rate ICC Intial capital cost AEP Annual energy production 24
  25. 25. 25 PLACE AOE COE TOPEKA $0.0102/KWH $0.0194/KWH DETROIT $0.0103/KWH, $0.0196/KWH SAN DIEGO $0.0129/KWH $0.0249/KWH
  26. 26. CONCLUSION  FEGs harness powerful & persistent winds –source for grid connection, for hydrogen production.  Main resource is the upper atmospheric winds  Less environmental impacts  Rural/remote area installations 26
  27. 27. REFERENCE [1] K. Caldeira, Seasonal, global wind resource diagrams [Online]. Available: www.skywindpower.com [2] R. J. O’Doherty and B. W. Roberts, “Application of upper wind data in one design of tethered wind energy system,” Solar Energy Res. Inst., Golden, CO,Tech. Rep. TR-211-1400, Feb. 1982, pp. 1–127. [3] J. D. Atkinson et al. , “The use of Australian upper wind data in the design of an electrical generating platform,” Chas. Kolling Res. Lab., Univ. of Sydney, Sydney, Australia, TN D-17, Jun. 1979, pp. 1–19. [4] B. W. Roberts and J. Blackler, “Various systems for generation of elec-tricity using upper atmospheric winds,” in Proc. 2nd Wind Energy Innov. Syst. C onf., Solar Energy Res. Inst., Colorado Springs, CO, Dec. 1980, pp. 67–80. [5] B. W. Roberts and D. H. Shepard, “Unmanned rotorcraft to 27
  28. 28. THANK YOU 28

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