validation of offshore load simulations using measurement data from the downvind project
DESCRIPTION
Validation of Offshore load simulations using measurement data from the DOWNVInD project. M. Seidel, F. Ostermann – REpower Systems AG Curvers, A.P.W.M. – Energy research Centre of the Netherlands (ECN), Petten, The Netherlands - PowerPoint PPT PresentationTRANSCRIPT
Validation of Offshore load
simulations using
measurement data from the
DOWNVInD project
Stand 06/09
M. Seidel, F. Ostermann – REpower Systems AG
Curvers, A.P.W.M. – Energy research Centre of the Netherlands (ECN), Petten, The Netherlands
Kühn, M.; Kaufer, D. – Endowed Chair of Wind Energy, University of Stuttgart, Germany
Böker, C. – ForWind, Institute for Steel Construction, Leibniz University Hannover, Germany
REpower Systems AG I 2
Agenda
Introduction
DOWNVInD measurements
Comparison of measurements with simulation
Coupling methods
Summary and outlook
REpower Systems AG I 3
Introduction
What is integrated analysis and why is it important?
(Turbulent) wind field
(Stochastic) wave loading on substructure
Complete turbine model (incl. e.g. electrical
system and controller)
Blade aerodynamics
Structural dynamics
Blade modes (flap & edge)
Global support structure mode
Local bracing mode
REpower Systems AG I 4
DOWNVInD measurements
The DOWNVInD Project has received funding from the Scottish Executive, the UK Department of Trade and Industry, and the European Commission. The support of these organizations is gratefully acknowledged.
DOWNVInD (Beatrice Demonstrator):
REpower Systems AG I 5
DOWNVInD measurements
Aim of the measurement programme:
Gain knowledge of the real load spectrum to assess fatigue lifetime of the main
components: substructure, tower and rotor blades;
To validate the load prediction models to increase the reliability of the future 1.000
MW wind farm.
Measurement programme has been drafted in close cooperation between
ECN (NL) and Teknikgruppen (SE); both involved in the evaluation programme
REpower Systems AG I 6
DOWNVInD measurements
Instrumentation plan:
Nacelle • wind speed
• Wind speed with Lidar on Beatrice A • Wave measurements with buoy
Dante systemsIn nacelle and tower base
Rotor blades• bending moments
Nacelle• main shaft bending and torsion• accelerations (5)• rotor position• rotor rotational speed• pitch angle• turbine status
Tower top• bending moments• shear forces
Tower base• bending moments• accelerations (3)• electric power
Substructure/Jacket• bending moments• axial forces
Total: 60 signals1,2 Gb per day
REpower Systems AG I 7
Coupling methods
Sequential coupling:
Substructure is reduced to 6x6 DOFs by Guyan reduction (static reduction)
System matrices (mass, stiffness, damping) and (wave) load time histories are generated inASAS(NL) and used in Flex 5
Retrieval run generates member forces in complete substructure
Integrated linearized Flex 5 - ASAS(NL) load calculations
ASAS(NL) Flex 5Excel
Generate model and load cases
Write ASAS(NL) input files and
batch files
Init deflection shapes
Flex 5 files generation run
(stiffness, damping, mass
matrix and loading history)
Integrated wind-wave loading
analysis
Retrieval run
Extract time series of member forces
Rainflow counting
Seidel, M. et. al.: Integrated analysis of wind and wave loading for complex support structures of Offshore Wind Turbines. Conference Proceedings Offshore Wind 2005, Copenhagen 2005.
REpower Systems AG I 8
Coupling methods
Full coupling:
Flex 5 and ASAS(NL) or Poseidon are running simultaneously Information is exchanged in each time step NO reduction of substructure is employed – system matrices are fully
retained
Flex5
FE-Code NewmarkSolver
NewmarkSolver
tn+1
tn+1
MFlex, DFlex, SFlex, FAero
, , x x x
tn-1
tn-1
tn
tn
Kaufer, D. et. al.: Integrated Analysis of the Dynamics of Offshore Wind Turbines with Arbitrary Support Structures. Proc. of EWEC 2009. Marseille: EWEC, 2009.
REpower Systems AG I 9
Coupling methods
19018017016015014013012011010090
48 000
46 000
44 000
42 000
40 000
38 000
36 000
34 000
32 000
30 000
28 000
26 000
24 000
22 000
20 000
18 000
MyTBf [kNm]
BendMomLng, TwrBse, fix
48 000
46 000
44 000
42 000
40 000
38 000
36 000
34 000
32 000
30 000
28 000
26 000
24 000
22 000
20 000
18 000
MyTBf [kNm] BendMomLng, TwrBse, fix
REpower Systems AG I 10
Comparison of sequential to full coupling
1
1 100
1 000
900
800
700
600
500
400
300
200
100
MyTBf [kNm]
BendMomLng, TwrBse, fix
1 100
1 000
900
800
700
600
500
400
300
200
100
MyTBf [kNm] BendMomLng, TwrBse, fix
Comparison at tower bottom (global response):
REpower Systems AG I 11
Comparison of sequential to full coupling
4321
1
MY [kNm ]
Element0009_Node0009
1
MY [kNm ] Element0009_Node0009
Comparison at a jacket brace (local response):
Full coupling: Red
Sequential coupling: Black
REpower Systems AG I 12
Comparison of measurements with simulation
Comparison for local member force in a jacket leg:
4321
0.75
0.7
0.65
0.6
0.55
0.5
0.45
0.4
0.35
0.3
0.25
0.2
0.15
0.1
0.05
mz [kNm]
B5 S4 B D L 1.45; MIP_TB_4_A2_C
0.75
0.7
0.65
0.6
0.55
0.5
0.45
0.4
0.35
0.3
0.25
0.2
0.15
0.1
0.05
MZ [kNm ] Element0010_Node0010
Measurement: Red
Simulation (full coupling): Black
REpower Systems AG I 13
Comparison of measurements with simulation
Comparison for an in-plane moment in a jacket brace:
4321
0.45
0.4
0.35
0.3
0.25
0.2
0.15
0.1
0.05
mz [kNm]
B5 S4 B U L 8.142; MIP_TB_6_A2_A
0.45
0.4
0.35
0.3
0.25
0.2
0.15
0.1
0.05
MZ [kNm ] Element0011_Node0011
Measurement: Red
Simulation (full coupling): Black
REpower Systems AG I 14
Summary and outlook
Summary:
Coupling methods work well for design calculations
Sequential coupling conservative compared to full coupling
Comparison with measurements indicates good performance
Outlook:
Further validation required with more complete measurements
Measurements to be used: RAVE (alpha ventus), about to be installed
now