Load Assumptions for the Design of electro mechanic Pitch Systems

Andreas ManjockGermanischer Lloyd Industrial Services GmbH, Business Segment Wind Energy

Andreas.Manjock@gl-group.com, www.gl-group.com/glwind

EWEC 2007 No. 2

Load Assumptions for the Design of electro mechanic Pitch Systems

1. Design of electro mechanic Pitch System

2. Simulation Model

3. Design Load Cases (DLCs)

4. Data Postprocessing

5. Conclusion and Outlook

Source: ENERCON

EWEC 2007 No. 3

Blade Bearing

1.1 Pitch System Components

Control Unit

Rotor Blade

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

PitchController

Drive MotorGear Box

iP

JPD

JRB

iPB

iPD

EWEC 2007 No. 4

Source: ENERCON

1. Design of electro mechanic Pitch System

2. Simulation Model2.1 Load Components2.2 System Model2.3 Local Model for Mesh Moment2.4 Drive Motor Characteristics2.5 Drive Motor Limitations2.6 Drive Control Scheme

3. Design Load Cases (DLCs)

4. Data Postprocessing

5. Conclusion and Outlook

Load Assumptions for the Design of electro mechanic Pitch Systems

EWEC 2007 No. 5

2.1 Load Components

Symbol Definition

αP Pitch Angle

MPDA Pitch Drive Actuator Torque

MZB Pitch Torque Rotor Blade

MR Friction Torque Blade Bearing

αP

Blade Root Coordinate System

MZB

MPDA

MR

Source: GL „Guideline for the Certification of Wind Turbines“, 2003

MR = M0 + µbend∙ Mres+ µaxial∙ Faxial+ µradial∙ Fradial

EWEC 2007 No. 6

2.2 System Model

Structural Model Global Simulation Model

Source: GH Bladed 3.67

iP2•JPD+JRB

α P

iP•M PDA

M R

M ZB

JPD•i P2•α P** JRB•α P**

EWEC 2007 No. 7

2.3 Local Model for Mesh Moment

Local MM - Assumption“

Mass System Pitch Drive

iP2•JPD

α P

iP•M PDA M M

JPD•i P2•α P**

Mass System Rotor Blade

+JRB

•M M

M R

M ZB

JRB •α P**

Split of Mass System provides Loads for Drive Train Components

α P

MM = MZB+ JRB ∙ αP** - MR

EWEC 2007 No. 8

2.4 Drive Motor Characteristics

MPDAiP P

PitchController

Control Unit

Drive Motor

Source: OAT Osterholz Antriebstechnik GmbH

EWEC 2007 No. 9

Source: OAT Osterholz Antriebstechnik GmbH

2.5 Drive Motor Limitations

EWEC 2007 No. 10

2.6 Drive Motor Control Scheme

PitchController

EWEC 2007 No. 11

1. Design of electro mechanic Pitch System

2. Simulation Model

3. Design Load Cases (DLCs)3.1 Identified Load Cases 3.2 Fatigue DLCs3.3 Extreme DLCs

4. Data Postprocessing

5. Conclusion and Outlook

Load Assumptions for the Design of electro mechanic Pitch Systems

Source: ENERCON

EWEC 2007 No. 12

3.2 Identified Load Cases

DLC1.2 Turbulence State

1 2 m/s 57.0% idling

2 5 m/s 30.0% power production

3 7 m/s 24.9% power production

4 9 m/s 22.0% power production

5 11 m/s 20.2% power production

6 13 m/s 18.9% power production

7 15 m/s 18.0% power production

8 17 m/s 17.3% power production

9 19 m/s 16.7% power production

10 21 m/s 16.3% power production

11 23 m/s 15.9% power production

12 25 m/s 15.6% power production

13 28 m/s 15.2% idling

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 25 m/s constant Pitch Runaway

Fatigue Load Cases Extreme Load Cases

Wind

EWEC 2007 No. 13

3.3 Fatigue DLCsControl Variables Load Variables

EWEC 2007 No. 14

3.4 Extreme DLCsControl Variables Load Variables

EWEC 2007 No. 15

1. Design of electro mechanic Pitch System

2. Simulation Model

3. Design Load Cases (DLCs)

4. Data Postprocessing4.1 Design Driver4.2 Loads for Drive Motor4.3 Loads for Gearbox4.4 Loads for Blade Bearing Mesh

5. Conclusion and Outlook

Load Assumptions for the Design of electro mechanic Pitch Systems

Source: ENERCON

EWEC 2007 No. 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 BladeBearing

LDD of MM - Mesh Torque

Distribution of MM vs. αP

(Pitch Angle Duration Distribution)

EWEC 2007 No. 17

4.2.1 Loads for Drive Motor• Operation States of Drive Motor, Confirmation of global Wind Turbine Simulation

EWEC 2007 No. 18

4.2.2 Thermal Loads for Drive Motor

Thermische Belastung des Pitchantrieb

MP

DA

rms [

Nm

]

normales Lagerreibmoment erhöhtes Lagerreibmoment

Normal bearing friction Increased bearing friction (+50%)

• Standard Deviation (RMS) of pitch actuator torque for thermal impact

• Efficiency of gear box and has to be considered

EWEC 2007 No. 19

4.3 Loads for Gearbox

Load Duration Distribution of Mesh Torque M_M, Variation of Blade Bearing Friction Level

1 2 3 4 5 6 7 8 9 10 11 12 13 14

Load Level Mesh Torque M_M

Dur

atio

n

No Friction

Low Friction

Medium Friction

High Friction

M_M > 0 M_M < 0

• Load Duration Distribution counting for Mesh Torque M_M

• Influence of Blade Bearing Friction Level comparatively low

EWEC 2007 No. 20

4.4 Loads for Blade Bearing Mesh• Load Duration Distribution counting for Mesh Torque M_M

• Pitch Angle Duration Distribution counting

EWEC 2007 No. 21

1. Design of electro mechanic Pitch System

2. Simulation Model

3. Design Load Cases (DLCs)

4. Data Postprocessing

5. Conclusion and Outlook

Load Assumptions for the Design of electro mechanic Pitch Systems

Source: ENERCON

EWEC 2007 No. 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 No. 23

Keep in Contact

Andreas ManjockGermanischer Lloyd Industrial Services

Andreas.Manjock@gl-group.com, www.gl-group.com/glwind