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  1. 1. Paer Id : 142 EFFECT OF HORIZONTAL WIND SHEAR ON FLICKER EMISSION SEVERITY IN WIND FARM. EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM Wednesday, December 11, 2013 1
  2. 2. Power Quality Parameters associated with wind energy ….. Continuity of service Variation in voltage magnitude. Short duration variation. Instantaneous interruption, sag, swell. Momentary interruption, sag, swell. Temporary interruption, sag, swell. Long duration variation. Interruption. Under Voltage. Overvoltage. Transient voltages and currents. Voltage unbalance. Waveform distortion. DC offset. Harmonics. Inter-harmonics. Notching. Noise. Flicker or voltage fluctuations. Power frequency variations. Power failure or blackout. Wednesday, December 11, 2013 EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM 2
  3. 3. Input parameters. Type of generator used for the wind turbine. Squirrel cage induction generator (SQIG). Doubly fed induction generator (DFIG). generator. Slip ring induction generator (SRIG). Permanent magnet synchronous generator (PMSG). DC Type of the turbine according to the axis of rotation. Horizontal axis. Vertical axis. Horizontal axis - Up-Wind Turbines Down-Wind Turbines Shrouded Wind Turbines Vertical axis wind turbines. 1.Windmill With Rotational Sails ( VAWT ) 2.Neo-Aerodynamic ( VAWT ) 3. Darrieus Wind Turbine ( VAWT ) 4. Giromill ( VAWT ) 5. Savonius Wind ( VAWT ) continuous and split blade 6. Windstar Turbines ( VAWT ) 7. Giromill Wind Turbine( VAWT ) 8. Flapping Panel Wind Turbine( VAWT ) 9. The Persian windmill 10. A cup anemometer is a drag-type vertical axis wind turbine Number of blades of the turbine rotor. One. Two. Three. Six. Types of blades and Length of blades Type of turbine according to location of blades - Upwind turbine Downwind turbine. Materials of the blades wood - sensitivity to moisture, high processing costs, low density, low stiffness glass fiber reinforced plastic (GFRP) - moderate stiffness, high strength, and moderate density. carbon fiber reinforced plastic (CFRP) - very high stiffness, high strength, light weight& low density. Aramid fibers - excellent environmental and thermal stability, static and dynamic fatigue resistance steel aluminum - density about a third that of steel, lightweight, weaker and less stiff than steel. nickel alloy steels- good corrosion and oxidation resistance. Types of tower - Steel tubular tower , Lattice tower, Guy wire tower and Height of Tower Speed of the wind 5 m/s. 10m/s. 15m/s 20m/s 25m/s Type of load. - Resistive. Inductive. Capacitive. 3
  4. 4. INFLUENCE OF HORIZONTAL WIND SHEAR ON FLICKER EMISSION SEVERITY IN WIND FARM. Indian Institute of technology Bombay conference presentation Wednesday, December 11, 2013 4
  5. 5. Horizontal wind shear  Horizontal wind shear is a micro scale meteorological phenomenon, in which there is a swift, sweeping alteration or disparity in the wind speed, across the rotor disc, over a comparatively petite horizontal distance, in the atmosphere in a squat span of time Wednesday, December 11, 2013 Indian Institute of technology Bombay conference presentation 5
  6. 6. Parameters stirring flicker emission severity Tower wake effect Type of load Short circuit capacity ratio Grid parameters Grid or network impedance phase angle Dynamics of generator and grid Tower shadow effect Blade pitching . Turbine parameters Wind turbine type or characteristics. Vertical wind shear Vshr, Wind parameters Parameters stirring flicker emission severity Mean wind speed Horizontal wind shear Wind turbulence intensity Wednesday, December 11, 2013 Indian Institute of technology Bombay conference presentation 6
  7. 7. Origins of horizontal wind shear. Low level temperature inversion Shallow lows Thunderstorms Sea breeze Frontal surfaces Microbursts Wednesday, December 11, 2013 Strong surface winds. Turbulent air Snow showers Mountain waves Jet streams Origins of horizontal wind shear. Convective storms Indian Institute of technology Bombay conference presentation 7
  8. 8. Flicker  Tao sun et al. , defined flicker as an imprint of unsteadiness of visual sensation, induced by a light stimulus, whose luminance or spectral distribution fluctuates with time, which can cause clientele’s exasperation.  Flicker is also defined as the measure of voltage deviation, which may cause brouhaha to consumer. Wednesday, December 11, 2013 Indian Institute of technology Bombay conference presentation 8
  9. 9.  A typical 600 kW wind turbine has a rotor diameter of 43-44 meters, i.e. a rotor area of some 1,500 square meters.  The rotor area determines how much energy a wind turbine is able to harvest from the wind.  Since the rotor area increases with the square of the rotor diameter, a turbine which is twice as large will receive 2 2 = 2 x 2 = four times as much energy.  To be considered a good location for wind energy, an area needs to have average annual wind speeds of at least 12 miles per hour.
  10. 10. Effect of Flickers….. Disturbance to photosensitive person. Light flicker and malfunction of electrical equipment and devices. Affect the production environment. Lower work concentration levels. Detrimental effect on electrical and electronic equipment. Nuisance tripping due to mis-operation of relays and contactors. Unwanted triggering of UPS units to switch to battery mode. Affect industrial processes relying on constant electrical power Wednesday, December 11, 2013 EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM 10
  11. 11. Wednesday, December 11, 2013 EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM 11
  12. 12. Vertical Wind Shear Ground Wednesday, December 11, 2013 EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM 12
  13. 13. Horizontal Wind Shear Horizontal Wind Shear ╞ Wind turbine Wind currents from top view Wednesday, December 11, 2013 EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM 13
  14. 14. Type of Wind shear Wind shear per second 0-3 Type of wind shear Weak 4-5 Moderate 6-7 Large Above 8 Extreme Wednesday, December 11, 2013 EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM 14
  15. 15. ESTIMATION OF SHORT TERMFLICKER ( PST) AND LONG TERM FLICKER (PLT) BY POWER QUALITY TEST.      POWER QUALITY TESTS OF WIND TURBINES EXPRESS FLICKER COEFFICIENT. FOR EACH WIND TURBINE. FOR DIFFERENT NETWORK PHASE ANGLE CONDITIONS. FOR DIFFERENT ANNUAL MEAN WIND SPEEDS FOR A WIND FARM. Wednesday, December 11, 2013 EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM 15 15
  16. 16. SHORT-TERM FLICKER EMISSION ( PST ) AND LONG TERM FLICKER EMMISSION (PLT) ARE ASSUMED SAME PST AND PLT ARE ASSUMED SAME BECAUSE IT IS ASSUMED THAT MEAN WIND SPEED AND TURBULENCE WILL BE SAME IN 10 MINUTES AND IN 120 MINUTES. EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM Wednesday, December 11, 2013 16 16
  17. 17. SHORT-TERM FLICKER EMISSION ( PST ) AND LONG TERM FLICKER EMMISSION (PLT) Wind parameters affecting Grid parameters affecting flicker flicker Deterministic parameters Short circuit capacity ratio Mean wind speed / wind (SCR). speed variation. Turbine parameters affecting flicker Blade pitching. Wind shear or gradient. (horizontal and vertical wind shear)., Tower shadow effect, tower wake effect. Stochastic parameters - Wind turbulence intensity. Grid / network impedance angle. Physical dynamics of wind turbine Electrical dynamics of generator and grid , type of load Wind turbine type / characteristics. EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM Wednesday, December 11, 2013 17 17
  18. 18. Wind tunnel for testing Wednesday, December 11, 2013 EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM 18
  19. 19. WORK DONE - DEVELOPMENT OF MATHRMATICAL MODEL FOR FLICKER EMMISSION EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM Wednesday, December 11, 2013 19 19
  20. 20. SHORT-TERM FLICKER EMISSION ( PST ) AND LONG TERM FLICKER EMMISSION (PLT) SK Ci (ΨK) Va --- SHORT CIRCUIT CAPACITY. ------ FLICKER COEFFICIENT OF WIND TURBINE i. ----- SPECIFIC NETWORK IMPEDANCE PHASE ANGLE. ----- ANNUAL AVERAGE WIND SPEED FROM SITE. Sn,i ---- RATED POWER OF WIND TURBINE i. Nwt ---- NUMBER OF WIND TURBINES IN WIND FARM. Wednesday, December 11, 2013 EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM 20 20
  21. 21. SHORT-TERM FLICKER EMISSION ( PST ) AND LONG TERM FLICKER EMMISSION (PLT) SK Ci (ΨK) Va --- SHORT CIRCUIT CAPACITY. ------ FLICKER COEFFICIENT OF WIND TURBINE i. ----- SPECIFIC NETWORK IMPEDANCE PHASE ANGLE. ----- ANNUAL AVERAGE WIND SPEED FROM SITE. Sn,i ---- RATED POWER OF WIND TURBINE i. Nwt ---- NUMBER OF WIND TURBINES IN WIND FARM. Wednesday, December 11, 2013 EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM 21 21
  22. 22. SHORT-TERM FLICKER EMISSION ( PST ) AND LONG TERM FLICKER EMMISSION (PLT) SK Ci (ΨK) Va --- SHORT CIRCUIT CAPACITY. ------ FLICKER COEFFICIENT OF WIND TURBINE i. ----- SPECIFIC NETWORK IMPEDANCE PHASE ANGLE. ----- ANNUAL AVERAGE WIND SPEED FROM SITE. Sn,i ---- RATED POWER OF WIND TURBINE i. Nwt ---- NUMBER OF WIND TURBINES IN WIND FARM. Wednesday, December 11, 2013 EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM 22 22
  23. 23. SHORT-TERM FLICKER t s ) 0.1 0.08 0.06 P ( k lic f m e t r o h S 0.04 Mean wind speed V ( m/s ) 0.02 0 0 5 10 Short term flicker ( pst ) 15 20 25 Poly. (Short term flicker ( pst )) 30 EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM Wednesday, December 11, 2013 23 23
  24. 24. Proposed Model Abbreviation Parameter N Number of blades Nsd Product of number of turbine blades and multiplying factor Pst Short term flicker emission severity (%) Rbt Ratio of twice turbine blade length to tower height. Hshr Horizontal wind shear ( per second ) Wednesday, December 11, 2013 EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM 24
  25. 25. Assumptions in Model  The tower is a tubular type of tower as for larger turbines lattice tower is not favored. Wind turbine considered is of large size ranging from 1 MW to 7 MW.  Wind speed variation is in between cut in and cut out speed. Normally cut in speed is 3 m/s, cut out speed is 25 m/s and rated speed is 11 m/s.  Turbine is upwind turbine fixed speed turbine . Majority of the turbines are upwind turbines and downwind turbines are rarely incorporated.  Temperature is 25 deg. C. The experiment conducted is a t 25 deg. C.. Wednesday, December 11, 2013 EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM 25
  26. 26. Variation of flicker due to Horizontal wind shear Flicker by empirical model for hilly topography and turbine with 2 blades Site Saswad ( India) Flicker by empirical model for flat topography with grass and turbine with 2 blades Site : - Nimgaon Mhalungi ( India) Flicker by empirical model for city region and turbine with 3 blades Site : - Lohagaon ( India) Recorded flicker at hilly topography and turbine with 2 blades Site :- Saswad ( India) Recorded flicker at flat topography with grass and turbine with 2 blades Site :- Nimgaon Mhalungi ( India) Recorded flicker at city region and turbine with 3 blades Site : - Lohagaon ( India) Hor Wednesday, December 11, 2013 EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM 26
  27. 27. Conclusion FLICKER IS NOT A LINEAR SUM OF ALL FLICKERS.  EQUATION TAKES INTO ACCOUNT THE “CANCELLATION” EFFECTS, WHICH COMES FROM WIND DYNAMICS IN WIND FARM THAT IS NOT CORRELATED, SO FLICKER IS NOT A LINEAR SUM OF ALL FLICKER PRODUCED FROM EACH WIND TURBINE.  BECAUSE 3P IS MAIN FLICKER CONTRIBUTION AND THESE RELATIVELY HIGH FREQUENCIES ARE APPROXIMATELY EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM Wednesday, December 11, 2013 UNCORRELATED. 27 27
  28. 28. Mitigations Methods of Flicker elimination Power System Reactive power compensation equipment and energy storage equipment. The Static VAR Compensator (SVC). Static compensator (STATCOM). Unified Power Flow Controller (UPFC). Wednesday, December 11, 2013 EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM 28
  29. 29. References Pedro Rosas, “Dynamic influences of wind power on the power system”, Ph.D. Dissertation, Section of Electric Power Engineering, Orsted Institute, Technical University of Denmark,. Mar. 2003. IEC 61400-21, Measurement and assessment of power quality characteristics of grid connected wind turbines, International Electrotechnical Commission, 2001 Wednesday, December 11, 2013 EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM 29
  30. 30. THANK YOU. EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM Wednesday, December 11, 2013 30 30
  31. 31. LARGE-SCALE INTEGRATION.  LARGE-SCALE INTEGRATION MEANS RELATIVELY HIGH WIND POWER COMPARED TO LOCAL POWER SYSTEM (ABOVE 10 % ).  LARGE-SCALE INTEGRATION PROBLEMS ARE BASED ON SMALL-SCALE ONES. EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM Wednesday, December 11, 2013 31 31
  32. 32. TYPES OF LARGE-SCALE INTEGRATION.  LARGE WIND FARMS CONNECTED TO  SEVERAL SMALL WIND FARMS CONNECTED TRANSMISSION SYSTEM . TO DISTRIBUTION SYSTEMS. EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM Wednesday, December 11, 2013 32 32
  33. 33. POWER QUALITY AND STABILITY ASSESSMENT IN LARGE-SCALE INTEGRATION OF WIND ENERGY.  DEPENDING ON SIZES, THEY DEMAND SPECIAL INVESTIGATIONS OF VOLTAGE AND FREQUENCY VARIATIONS FOR ASSESSMENT OF VOLTAGE STABILITY AND POWER QUALITY.  IN SMALL-SCALE INTEGRATION, FREQUENCY IS ASSUMED CONSTANT. Wednesday, December 11, 2013 EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM 33 33
  34. 34. EFFECTS OF LARGE-SCALE INTEGRATION.  WITH HIGH WIND POWER CAPACITY INSTALLED, LARGE ACTIVE POWER VARIATIONS CAN INTERACT WITH FREQUENCY CONTROLLERS IN THE CONVENTIONAL POWER STATIONS, SO FREQUENCY VARIATIONS CAN OCCUR.  IN ADDITION, LARGE REACTIVE POWER DEMANDED BY WIND FARMS CAN REDUCE REACTIVE POWER SUPPLY.  EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM HENCE VOLTAGE STABILITY LIMITS CAN BE REDUCED. Wednesday, December 11, 2013 34 34
  35. 35. FOCUS- VOLTAGE STABILITY AND DYNAMIC POWER OSCILLATION.  HERE FOCUS IS ON VOLTAGE STABILITY  DYNAMIC POWER OSCILLATIONS DURING AND NORMAL OPERATION OF POWER SYSTEM. EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM Wednesday, December 11, 2013 35 35
  36. 36. SINGLE LINE DIAGRAM OF BASIC STRUCTURE OF POWER SYSTEM. EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM Wednesday, December 11, 2013 36 36
  37. 37. EFFECTR OF MEAN WIND SPEED ON FLICKER FOR FIXED WIND TURBINES .   IN FIXED SPEED WIND TURBINE FLICKER INCREASES WITH INCREAING WIND SPEED FLICKER LEVEL INCREASES THREE TIMES FROM LOWER TO HIGHER WIND SPEEDS. EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM Wednesday, December 11, 2013 37 37
  38. 38. EFFECT WIND SPEED VARIATION ON POWER  VARIATION IN WIND SPEED OF +/- 1 % GIVE POWER FLUCTUATION OF +/-20 % EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM Wednesday, December 11, 2013 38 38
  39. 39. FLICKER FOR FIXED AND VARIABLE SPEED WIND TURBINE  FLICKER IN FIXED SPEED WIND TURBINE IS MORE FLICKER THAN FOR VARIABLE SPEED WIND TURBINE. EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM Wednesday, December 11, 2013 39 39
  40. 40. EFFECT OF GRID IMPEDANCE ANGLE ON FLICKER FOR FIXED WIND TURBINE   FLICKER IN FIXED SPEED IS MORE SENSITIVE TO GRID ANGLE THAN FOR VARIABLE SPEED FOR FIXED SPEED WIND TURBINE FLICKER IS MORE FOR HIGH GRID ANGLES THAN FOR VARIABLE SPEED VARIABLE SPEED WIND TURBINE EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM Wednesday, December 11, 2013 40 40
  41. 41.  ACCEPTABLE FLICKER FOR TRANSMISION NETWORK FOR WIND TURBINES CONNECTED TO TRANSMISSION NETWORK THE FLICKER CONTRIBUTION FROM WIND TURBINE SHALL BE LIMITED TO Pst = 0.3 AND BELOW. EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM Wednesday, December 11, 2013 41 41
  42. 42.  ACCEPTABLE FLICKER FOR DISTRIBUTION NETWORK FOR WIND TURBINES CONNECTED TO TRANSMISSION NETWORK THE FLICKER CONTRIBUTION FROM WIND TURBINE SHALL BE LIMITED TO Pst = 0.35 AND BELOW. EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM Wednesday, December 11, 2013 42 42
  43. 43. WAYS OF ANALYSIS OF FLICKER   CUMULATIVE PROBABILITY P(l) FUNCTION OF INSTANTANEOUS FLICKER LEVEL. SHORT TERM FLICKER SEVERITY VALUE / LONG TERM FLICKER SEVERITY VALUE. EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM Wednesday, December 11, 2013 43 43
  44. 44. WHY SHORT TERM AND LONG TERM FLICKER AR SAME      FLICKER IS A FUNCTION OF WIND SPEED. LOND TERM FLICKER IS MEASURED FOR 2 HOURS I.E. FOR 120 MINUTES. SHORT TERM FLICKER IS MEASURED FOR 10 MINUTES. CALCULATIONS OF 12 CONTINUOUS SHORT TERM FLICKER VALUE IS VERY CLOSE IN 2 HOURS. SO PLT AND PST ARE SAME Wednesday, December 11, 2013 EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM 44 44
  45. 45. INNOVATION IN WORK DONE    FOR FINDING FLICKER FOLLOWING NEW PARAMETER is INTRODUCED VERTICAL WIND SHEAR/ HORIZONTAL WIND SHEAR. FLICKER IS ONE OF THE WAY TO EVALUATE THE DYNAMIC PERFORMANCE OF WIND TURBINE. EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM Wednesday, December 11, 2013 45 45
  46. 46. FLICKER VARIATION WITH MEAN WIND SPEED EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM Wednesday, December 11, 2013 46 46
  47. 47. FLICKER VARIATION WITH TURBULENCE INTENSITY EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM Wednesday, December 11, 2013 47 47
  48. 48. FLICKER VARIATION WITH SHORT CIRCUIT CAPACITY. EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM Wednesday, December 11, 2013 48 48
  49. 49. FLICKER VARIATION WITH GRID IMPEDANCE ANGLE. EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM Wednesday, December 11, 2013 49 49
  50. 50. FLICKER VARIATION TURBULENCE INTENSITY EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM Wednesday, December 11, 2013 50 50
  51. 51. THANK YOU. EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM Wednesday, December 11, 2013 51 51

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