142 k datta

Paer Id : 142EFFECT OF HORIZONTAL WIND SHEAR ON FLICKER

EMISSION SEVERITY IN WIND FARM.

Friday, April 7, 2023

EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM

Friday, April 7, 2023EFFECT OF VERTICAL WIND SHEAR

ON FLICKER IN WIND FARM2

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.

Power Quality Parameters associated with wind energy …..

Input parameters.Type of generator used for the wind turbine.Squirrel cage induction generator (SQIG). Slip ring induction generator (SRIG).Doubly fed induction generator (DFIG). Permanent magnet synchronous generator (PMSG). DC generator.Type of the turbine according to the axis of rotation. - Horizontal axis. Vertical axis.Horizontal axis - Up-Wind Turbines Down-Wind Turbines Shrouded Wind TurbinesVertical 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 turbineNumber of blades of the turbine rotor. One. Two. Three. Six.Types of blades and Length of bladesType of turbine according to location of blades - Upwind turbine Downwind turbine.Materials of the bladeswood - sensitivity to moisture, high processing costs, low density, low stiffnessglass 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/sType of load. - Resistive. Inductive. Capacitive.

INFLUENCE OF HORIZONTAL WIND SHEAR ON FLICKER EMISSION SEVERITY IN WIND FARM.

Indian Institute of technology Bombay conference presentation

Horizontal wind shear

Friday, April 7, 2023Indian Institute of technology Bombay

conference presentation 5

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

Parameters stirring flicker emission severity

Short circuit capacity ratio

Type of load

Blade pitching

Dynamics of generator and grid

Grid or network impedance phase angle Wind turbine type or characteristics.

Parameters stirring flicker

emission severity

Horizontal wind shear

Tower shadow effect

Wind parameters Grid parameters . Turbine parameters

Mean wind speed

Vertical wind shear Vshr,

Tower wake effect

Wind turbulence intensity

Origins of horizontal wind shear.

Shallow lows

Low level temperature inversion

Sea breeze Turbulent air

Strong surface winds.

Thunderstorms

Microbursts

Frontal surfaces

Convective storms

Mountain waves

Origins of horizontal

wind shear. Jet streams

Snow showers

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.

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 22 = 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.

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

Effect of Flickers…..

Vertical Wind Shear

Ground

Horizontal Wind Shear Horizontal Wind Shear

Wind currents from top view

╞Wind turbine

Type of Wind shear

Wind shear per second

Type of wind shear

0-3 Weak

4-5 Moderate

6-7 Large

Above 8 Extreme

ESTIMATION OF SHORT TERMFLICKER ( PST) AND LONG TERM FLICKER (PLT) BY POWER QUALITY TEST.

Friday, April 7, 2023 EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM 15

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.

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.

SHORT-TERM FLICKER EMISSION ( PST ) AND LONG TERM FLICKER EMMISSION (PLT)

Friday, April 7, 2023EFFECT OF VERTICAL WIND SHEAR ON FLICKER IN WIND FARM

Wind parameters affecting flicker

Grid parameters affecting flicker

Turbine parameters affecting flicker

Deterministic parameters -Mean wind speed / wind speed variation.

Short circuit capacity ratio (SCR).

Blade pitching.

Wind shear or gradient. (horizontal and vertical wind shear)., Tower shadow effect, tower wake effect.

Grid / network impedance angle.

Physical dynamics of wind turbine

Stochastic parameters - Wind turbulence intensity.

Electrical dynamics of generator and grid , type of load

Wind turbine type / characteristics.

Wind tunnel for testing

WORK DONE - DEVELOPMENT OF MATHRMATICAL MODEL FOR FLICKER EMMISSION

SK --- SHORT CIRCUIT CAPACITY.

Ci ------ FLICKER COEFFICIENT OF WIND TURBINE i.

(ΨK) ----- SPECIFIC NETWORK IMPEDANCE PHASE ANGLE.

Va ----- ANNUAL AVERAGE WIND SPEED FROM SITE.

Sn,i ---- RATED POWER OF WIND TURBINE i.

Nwt ---- NUMBER OF WIND TURBINES IN WIND FARM.

SHORT-TERM FLICKER

0 5 10 15 20 25 30Short term flicker ( pst ) Poly. (Short term flicker ( pst ))

Mean wind speed V ( m/s )

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 )

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..

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)

ConclusionConclusionFLICKER 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

UNCORRELATED. 27

Reactive power compensation equipment and energy storage equipment.

The Static VAR Compensator (SVC).

Static compensator (STATCOM).

Unified Power Flow Controller (UPFC).

Mitigations Methods of Flicker elimination Power System

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

THANK YOU.

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.

TYPES OF LARGE-SCALE INTEGRATION.

LARGE WIND FARMS CONNECTED TO

TRANSMISSION SYSTEM .

SEVERAL SMALL WIND FARMS CONNECTED

TO DISTRIBUTION SYSTEMS.

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. 33

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.

HENCE VOLTAGE STABILITY LIMITS CAN BE REDUCED.

FOCUS- VOLTAGE STABILITY AND DYNAMIC POWER OSCILLATION.

HERE FOCUS IS ON VOLTAGE STABILITY

DYNAMIC POWER OSCILLATIONS DURING

NORMAL OPERATION OF POWER SYSTEM.

SINGLE LINE DIAGRAM OF BASIC STRUCTURE OF POWER SYSTEM.

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 WIND SPEED VARIATION ON POWER

VARIATION IN WIND SPEED OF +/- 1 % GIVE

POWER FLUCTUATION OF +/-20 %

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 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

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.

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.

WAYS OF ANALYSIS OF FLICKER

CUMULATIVE PROBABILITY P(l) FUNCTION OF

INSTANTANEOUS FLICKER LEVEL.

SHORT TERM FLICKER SEVERITY VALUE / LONG

TERM FLICKER SEVERITY VALUE.

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

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.

FLICKER VARIATION WITH MEAN WIND SPEED

FLICKER VARIATION WITH TURBULENCE INTENSITY

FLICKER VARIATION WITH SHORT CIRCUIT CAPACITY.

FLICKER VARIATION WITH GRID IMPEDANCE ANGLE.

FLICKER VARIATION TURBULENCE INTENSITY

THANK YOU.

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