prof. joachim reuder, geophysical institute, university of … days sept 19/s3 r… · the...

The potential of lidar technology for wind power meteorology Prof. Joachim Reuder, Geophysical Institute, University of Bergen

NORCOWE days, Bergen 19.09.2012

Outline

• Introduction

• lidar principle

• lidar wind profilers

• scanning lidar systems

• multiple beam systems

J.- Reuder, Geophysical Institute, University of Bergen NORCOWE days, 19.09.2012, Bergen

motivation/fields of research

• wind resource estimates (10 min averages, turbulence intensity, wind shear)

• power curve determination

• monitoring of the incoming wind field for turbine control purposes

• investigation of wake effects

• single turbine

• near wake effects inside wind parks

• far wake effect behind larger wind farms


Introduction

• LIDAR (light detection and ranging)

• acronym was introduced in 1953 in the book “Weather Instruments” (before the invention of lasers)

• laser (light amplification by the stimulated emission of radiation) first used by Gordon Gould in 1958

• main application in the beginning: distance measurements for military applications

• from mid of the 1970s increasing activities for the use of lidars in atmospheric research, now covering a wide range of applications

• determination of tropospheric aerosol concentration and properties

• stratospheric ozone profiles

• temperature and winds in the mesosphere (ca 90 km altitude)

• application of for wind measurements in the lower troposphere are relatively new


Measurement principle

• sending out photons at an

infrared wavelength of

typically around 1.5 mm (in

pulses or continuously)

• the Doppler-shift of photons

backscattered at aerosol

particles moved with the

wind is measured

• measurement in at least 3

different directions enables

the determination of the 3

dimensional wind vector

Source: http://www.leosphere.com/file/leosphere_windcube.pdf


pulsed lidar


Source: http://www.leosphere.com/file/leosphere_windcube.pdf

Vr27

0

V V

V

V

Vr0

Vr18

0

Vr9

0

a

Typical measurement pattern:

• ~ 10000 laser pulses emitted in

each direction (total ca. 0.5 s)

• measuring in different directions

(typically steps of 90 degrees)

Measurement hypothesis :

• Homogeneous and stationary

wind conditions

continuous wave (cw) lidar


Source: http://www.scribd.com/doc/30195938/Natural-Power-ZephIR-Brochure-Ecopy

Typical measurement pattern:

• the laser beam is focussed to a

given altitude

• a certain number of

measurements is taken over a

circular scan pattern (typically 50

measurements of 20 ms each)

• the laser is focussed to the next

altitude

pulsed lidar – continuous wave (cw) lidar


Pulsed lidar Continuous lidar

Pros Measures all altitudes

simultaneously

Fast full profile measurement

No altitude ambiguity

Fast single point measurement

(20ms)

Low minimum altitude (10m)

High vertical resolution at low

altitudes

Cons − Slow single point measurement

(0.5 s)

− Higher complexity and cost

− High minimum altitude (40 m)

and modest vertical resolution

(20 m)

− Slow full profile measurement

− Vertical resolution decreases

with increasing altitude

− Possible altitude ambiguity

− Limited maximum altitude (200-

300 m)

Courtesy: Jon Hellevang, CMR Instrumentation

commercially available wind profilers


Windcube (Leosphere)

ZephIR (Natural Powers)

Gallion (Sgurr Energy)

Vindicator (Catch the Wind)

comparison lidar - mast


Courtesy: Michael Courtney, DTU, Risø

A good sited and good maintained wind lidar can provide wind data with

a quality comparable to cup anemometers; mast effects (wake/speed

up) on the cup measurements have to be excluded

Windcube vs Cup at 80my = 0.9468x + 0.2685

R2 = 0.9071

y = 0.9788x

R2 = 0.9058

0

5

10

15

20

25

0 5 10 15 20 25

Cup speed 80m [m/s]

Lid

ar

sp

ee

d [

m/s

]

Windcube vs Cup at 80my = 0.9969x - 0.0447

R2 = 0.9962

y = 0.9922x

R2 = 0.9962

0

5

10

15

20

25

0 5 10 15 20 25

Cup speed 80m [m/s]L

ida

r s

pe

ed

[m

/s]

scanning lidar systems


Gallion (Sgurr Energy)

range: 4000 m

resolution 40 m

Leosphere

WindCube 100S/200S

range: 3000 - 6000 m

resolution 50 – 100 m

measurement geometries


PPI (plan position indicator): azimuth-scan

E N

W

S height

RHI (range height indicator): elevation scan

N

N

W

height

height

W O S



Source: http://halo-photonics.com/Galion-data-examples.htm

30 minute average over

multiple PPI scans

single PPI scan in an active

wind park



Source: http://presentations.copernicus.org/EGU2012-8708_presentation.pdf courtesy G.V. Iungo



Source: http://www.ifb.uni-stuttgart.de/en/forschung/windenergie/research-projects/296-lidarswe

lidar going offshore


• why?

• poor information on the offshore wind field in the relevant height interval (30..200 m)

• corresponding mast structures are expansive and rather inflexible

• challenges:

• motion avoidance or motion correction

• adaptation to harsh marine environment

• energy for long term deployments

lidar going offshore


SeaZephIR

(Natural Power)

ZephIR lidar on

spare or tension

leg buoy

Flidar

(3E)

Windcube on

industrial buy;

mechanical

stsbilization

WindSentinel

(Axys)

Vindicator on a

boat structure

Wavescan ZephIR

(Fugro Oceanor)

ZephIR on

Wavescan buoy

lidar movement testing


Stewart platform

• R&D project under participation

of several NORCOWE and

NOWITECH partners

• application of 55 different motion

patterns on a 6-DOF motion

platform, 3 hours each

offshore comparison


source: Final Report of the project “Measurements of Wind Profile from a Buoy using Lidar” in cooperation between Fugro OCEANOR, Statoil, University of Bergen, Uni Research, Christian Michelsen Research (CMR) and Marintek

multiple beam systems


source: http://www.risoe.dtu.dk/research/sustainable_energy/wind_energy/projects/vea_wind_scanner.aspx?sc_lang=en/

WindScanner: EU joint

research infrastructures

project under lead of DTU in

Denmark

• 3 beams measuring

simultaneous in one

positionLeosphere

• inststanteneous information

on wind speed (and

turbulence) at one point

without the assumption of

homogeneity of the wind

field

prof. joachim reuder, geophysical institute, university of … days sept 19/s3 r… · the...

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