1. Load Assumptions for the Design of electro mechanic Pitch Systems
Andreas Manjock
Germanischer Lloyd Industrial Services GmbH, Business Segment Wind Energy

2. Load Assumptions for the Design of electro mechanic Pitch Systems
Simulation Model
Design Load Cases (DLCs)
Data Postprocessing
Conclusion and Outlook
Source: ENERCON
EWEC 2007

3. 1.1 Pitch System Components
Blade Bearing
Gear Box
Rotor Blade
Drive Motor
Symbol
Definition
JPD
Moment of Inertia, Pitch Motor
JRB
Moment of Inertia, Rotor Blade
iPD
Ratio of Pitch Drive Gearbox
iPB
Ratio of Pitch Bearing Mesh iP
Ratio of entire Pitch System iP
JPD
JRB
iPB
iPD
Control Unit
Pitch Controller
EWEC 2007

4. Load Assumptions for the Design of electro mechanic Pitch Systems
Simulation Model 2.1 Load Components 2.2 System Model 2.3 Local Model for Mesh Moment 2.4 Drive Motor Characteristics 2.5 Drive Motor Limitations 2.6 Drive Control Scheme
Design Load Cases (DLCs)
Data Postprocessing
Conclusion and Outlook
Source: ENERCON
EWEC 2007

5. Blade Root Coordinate System
2.1 Load Components αP
Blade Root Coordinate System
MZB
Symbol
Definition αP
Pitch Angle
MPDA
Pitch Drive Actuator Torque
MZB
Pitch Torque Rotor Blade MR
Friction Torque Blade Bearing MR
MPDA
MR = M0 + µbend∙ Mres+ µaxial∙ Faxial+ µradial∙ Fradial
Source: GL „Guideline for the Certification of Wind Turbines“, 2003
EWEC 2007

6. Global Simulation Model
2.2 System Model
Structural Model
Global Simulation Model
Source: GH Bladed 3.67 i P 2 • J PD +J RB α •M
PDA M R ZB •i **
EWEC 2007

7. 2.3 Local Model for Mesh Moment
Local MM - Assumption“ α +J RB •M M R ZB J •α P ** α P P i P •M
PDA M J PD •i P 2 • α ** i 2 • J P PD
Mass System Pitch Drive
Mass System Rotor Blade
Split of Mass System provides Loads for Drive Train Components
MM = MZB+ JRB ∙ αP** - MR
EWEC 2007

8. 2.4 Drive Motor Characteristics
iP  P
MPDA
Control Unit
Pitch Controller
Source: OAT Osterholz Antriebstechnik GmbH
EWEC 2007

9. 2.5 Drive Motor Limitations
Source: OAT Osterholz Antriebstechnik GmbH
EWEC 2007

10. 2.6 Drive Motor Control Scheme
Pitch Controller
EWEC 2007

11. Load Assumptions for the Design of electro mechanic Pitch Systems
Simulation Model
Design Load Cases (DLCs) Identified Load Cases Fatigue DLCs Extreme DLCs
Data Postprocessing
Conclusion and Outlook
Source: ENERCON
EWEC 2007

12. 3.2 Identified Load Cases Fatigue Load Cases Extreme Load Cases DLC1.2
Turbulence
State 1 2
m/s
57.0%
idling 5
30.0%
power production 3 7
24.9% 4 9
22.0% 11
20.2% 6 13
18.9% 15
18.0% 8 17
17.3% 19
16.7% 10 21
16.3% 23
15.9% 12 25
15.6% 28
15.2%
Wind
Load Case
Wind
Gust Type
Event
DLC1.5
12 m/s
EOG1
Grid Loss
DLC1.6
25 m/s
EOG50
Active Safety Syst.
DLC2.2
constant
Pitch Runaway
EWEC 2007

13. 3.3 Fatigue DLCs
Control Variables
Load Variables
EWEC 2007

14. 3.4 Extreme DLCs
Control Variables
Load Variables
EWEC 2007

15. Load Assumptions for the Design of electro mechanic Pitch Systems
Simulation Model
Design Load Cases (DLCs)
Data Postprocessing 4.1 Design Driver 4.2 Loads for Drive Motor 4.3 Loads for Gearbox 4.4 Loads for Blade Bearing Mesh
Conclusion and Outlook
Source: ENERCON
EWEC 2007

16. 4.1 Design Driver Pitch System Component Type of Load Drive Motor
MPDA - Pitch Actuator Torque
αP* - Speed of Pitch Actuator
RMS(MPDA ) - Thermal Loading
Gearbox
LDD of MM - Mesh Torque
(Load Duration Distribution)
Mesh of Blade Bearing
Distribution of MM vs. αP
(Pitch Angle Duration Distribution)
EWEC 2007

17. 4.2.1 Loads for Drive Motor
Operation States of Drive Motor, Confirmation of global Wind Turbine Simulation
EWEC 2007

18. 4.2.2 Thermal Loads for Drive Motor
Standard Deviation (RMS) of pitch actuator torque for thermal impact
Efficiency of gear box and has to be considered
Normal bearing friction Increased bearing friction (+50%)
EWEC 2007

19. 4.3 Loads for Gearbox
Load Duration Distribution counting for Mesh Torque M_M
Influence of Blade Bearing Friction Level comparatively low
M_M > 0
M_M < 0
EWEC 2007

20. 4.4 Loads for Blade Bearing Mesh
Load Duration Distribution counting for Mesh Torque M_M
Pitch Angle Duration Distribution counting
EWEC 2007

21. Load Assumptions for the Design of electro mechanic Pitch Systems
Simulation Model
Design Load Cases (DLCs)
Data Postprocessing
Conclusion and Outlook
Source: ENERCON
EWEC 2007

22. 5 Conclusion and Outlook
Aerodynamic pitch Moment MZB is not sufficient for the design of pitch systems drive train Pitch Actuator Torque is inevitable
Blade bearing friction model included in the global simulation model
Integration of drive control unit into the global simulation model, e.g. limitations in speed and torque of pitch drive actuator
80% damage within first 20°- 25° of blade bearing mesh
Measurements on drive trains of pitch systems to validate MM-assumption
EWEC 2007

23. Keep in Contact
Andreas Manjock Germanischer Lloyd Industrial Services
EWEC 2007