Determining Mechanical Loads for Wind Turbines Grid Pitch Yaw Rotor Speed Blades Tower Geartrain Generator Hub Lift Wind FE Modes Blade Determining Mechanical Loads for Wind Turbines Steve Miller Technical Marketing, Physical Modeling MathWorks http://www.mathworks.com/physical-modeling/

Key Points Key Takeaways Summarize the key points about this release. Blade Efficient development requires the ability to control the tradeoff between model fidelity and simulation speed Creating reusable models of custom physical elements eliminates redundant work Access to different modeling approaches lets you include the right amount of detail FE Modes

Agenda Wind turbine system-level model Modeling the blades and pitch linkage Adding flexible bodies to the system Modeling the geartrain Adding custom mechanical elements Adding aerodynamics loads

Model Blade Pitch Linkage Problem: Model the blade pitch actuation linkage in the Simulink environment Solution: Use SimMechanics to model the mechanical linkage

Agenda Wind turbine system-level model Modeling the blades and pitch linkage Adding flexible bodies to the system Modeling the geartrain Adding custom mechanical elements Adding aerodynamics loads

Flexible Bodies in SimMechanics Lumped parameter approach Chain of rigid elements connected by spring/dampers Finite Element Approach Export eigenmodes from FE program and import into Simulink Superimpose deflection due to flexibility onto rigid body motion Rigid Body FE Software 1 2 3 4 Massless Body Reaction Force State-Space Model Deflection Joint Deflection Motion Rigid Body

Flexible Blades in SimMechanics Model: Problem: Model the blades as flexible cantilevers in the Simulink environment. Solution: Use SimMechanics to model the flexible body with two approaches (lumped parameter, imported FEA modes). Massless Body State-Space Model Deflection Joint Rigid Body

Agenda Wind turbine system-level model Modeling the blades and pitch linkage Adding flexible bodies to the system Modeling the geartrain Adding custom mechanical elements Adding aerodynamics loads

Modeling the Geartrain in SimDriveline Hub Shaft Generator Shaft Helical Gear Helical Gear Planetary Gear Problem: Model the geartrain of the wind turbine within the Simulink environment to determine the torque loads. Solution: Use SimDriveline to model the geartrain.

Agenda Wind turbine system-level model Modeling the blades and pitch linkage Adding flexible bodies to the system Modeling the geartrain Adding custom mechanical elements Adding aerodynamics loads

Creating Custom Models of Physical Components Torque = - Problem: Create a new physical modeling component for use in the Simulink environment using this equation. Solution: Use the Simscape language to model the component. MATLAB based Object-oriented Define implicit equations (DAEs and ODEs)

Extend and Create Libraries Define the physical ports for the Simscape block Reuse existing physical domains to extend libraries Define new physical domains

Define User Interface Parameters, default values, units, and dialog box text all defined in the Simscape file (extension .ssc)

Simscape Language: MATLAB Based Use MATLAB functions and expressions for typical physical modeling tasks: Analyze parameters Perform preliminary computations Initialize system variables Syntax closely follows MATLAB language

Create Reusable Components Equations defined in a text-based language Based on variables, their time derivatives, parameters, etc. Define simultaneous equations Can be DAEs, ODEs, etc. Assignment not required Specifying inputs and outputs n ot required Torque = - Angular Velocity =

Model Components Spanning Additional Physical Domains Electrical Electrochemical and electrical Model components in nearly any physical domain (hydraulic, pneumatic, etc.)

Agenda Wind turbine system-level model Modeling the blades and pitch linkage Adding flexible bodies to the system Modeling the geartrain Adding custom mechanical elements Adding aerodynamics loads

Model the Force of the Wind on the Blades Single Element Model Drag Lift Model: Wind Wind Moment Multiple Element Model Problem: Model the loads on the blades due to the wind and the spinning of the blades Solution: Use Simulink and Embedded MATLAB to create models at varying levels of detail Drag Lift Wind

Modeling the Forces on the Blades: Calculating Lift and Drag Force on blade depends upon wind speed, direction, and rotor speed Lift Drag Lift = 0.5*v2*Area*ρ*CL Drag = 0.5*v2*Area*ρ*CD Where CL&CD= f(Angle of Attack, Re,…) Positive Pitch Angle (θ) Rotation Wind = Rotor Speed(ω)*radius Inflow Angle = atan Pure Wind Rotation Wind Pure Wind (Vinf) α Resultant Wind = Angle of Attack(α) Inflow Angle - Pitch Angle

Modeling the Forces on the Blades: Segmented Blade Approach Wind speed varies along the blade Use Embedded MATLAB to model the force Rotation Wind

Key Points Key Takeaways Summarize the key points about this release. Blade Efficient development requires the ability to control the tradeoff between model fidelity and simulation speed Creating reusable models of custom physical elements eliminates redundant work Access to different modeling approaches lets you include the right amount of detail FE Modes

Automatically Generating C Code Model: Do not use in R2011a P1 P2 Px 10 … 100 Problem: Minimize the simulation time on a parameter sweep to determine controller parameters. Solution: Use Simulink Coder to create standalone executable. Standalone Executable Parameters 1 Parameters 2 Parameters 3 Parameters 4

Parameter Sweep using Code Generation Steps to perform parameter sweep 1) Build standalone executable 2) Generate different parameter sets 3) Run standalone simulation 4) Plot results Do not use in R2011a Standalone Executable >>rtwbuild(Model_Name); Parameters 1 >>[rtpstruct]= rsimgetrtp(Model_Name); Parameters 2 Parameters 3 Parameters 4 >>!<model name> -p <parameters>.mat -o <results>.mat

Parameter Sweep using Code Generation Advantages of using standalone executable Enables rapid simulation with different parameter sets ideal for batch testing or Monte Carlo simulation. Simulations can be run on different computers, reducing analysis time. Do not use in R2011a