# Inverse Load Calculation of Wind Turbine Support Structures - A Numerical Verification Using the Comprehensive Simulation Code FAST: Preprint (Revised)

## Abstract

Physically measuring the dynamic responses of wind turbine support structures enables the calculation of the applied loads using an inverse procedure. In this process, inverse means deriving the inputs/forces from the outputs/responses. This paper presents results of a numerical verification of such an inverse load calculation. For this verification, the comprehensive simulation code FAST is used. FAST accounts for the coupled dynamics of wind inflow, aerodynamics, elasticity and turbine controls. Simulations are run using a 5-MW onshore wind turbine model with a tubular tower. Both the applied loads due to the instantaneous wind field and the resulting system responses are known from the simulations. Using the system responses as inputs to the inverse calculation, the applied loads are calculated, which in this case are the rotor thrust forces. These forces are compared to the rotor thrust forces known from the FAST simulations. The results of these comparisons are presented to assess the accuracy of the inverse calculation. To study the influences of turbine controls, load cases in normal operation between cut-in and rated wind speed, near rated wind speed and between rated and cut-out wind speed are chosen. The presented study shows that the inverse load calculation is capable ofmore »

- Authors:

- Publication Date:

- Research Org.:
- National Renewable Energy Lab. (NREL), Golden, CO (United States)

- Sponsoring Org.:
- USDOE Office of Energy Efficiency and Renewable Energy Wind and Water Power Program

- OSTI Identifier:
- 1038322

- Report Number(s):
- NREL/CP-5000-54675

TRN: US201208%%422

- DOE Contract Number:
- AC36-08GO28308

- Resource Type:
- Conference

- Resource Relation:
- Conference: Presented at the 53rd Structures, Structural Dynamics, and Materials Conference, 23-26 April 2012, Honolulu, Hawaii

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 17 WIND ENERGY; ACCURACY; AERODYNAMICS; ELASTICITY; ROTORS; SIMULATION; TURBINES; VELOCITY; VERIFICATION; WIND TURBINES; WIND; WIND TURBINE SUPPORT STRUCTURES; DYNAMIC RESPONSE; Wind Energy

### Citation Formats

```
Pahn, T., Jonkman, J., Rolges, R., and Robertson, A.
```*Inverse Load Calculation of Wind Turbine Support Structures - A Numerical Verification Using the Comprehensive Simulation Code FAST: Preprint (Revised)*. United States: N. p., 2012.
Web. doi:10.2514/6.2012-1735.

```
Pahn, T., Jonkman, J., Rolges, R., & Robertson, A.
```*Inverse Load Calculation of Wind Turbine Support Structures - A Numerical Verification Using the Comprehensive Simulation Code FAST: Preprint (Revised)*. United States. doi:10.2514/6.2012-1735.

```
Pahn, T., Jonkman, J., Rolges, R., and Robertson, A. Thu .
"Inverse Load Calculation of Wind Turbine Support Structures - A Numerical Verification Using the Comprehensive Simulation Code FAST: Preprint (Revised)". United States. doi:10.2514/6.2012-1735. https://www.osti.gov/servlets/purl/1038322.
```

```
@article{osti_1038322,
```

title = {Inverse Load Calculation of Wind Turbine Support Structures - A Numerical Verification Using the Comprehensive Simulation Code FAST: Preprint (Revised)},

author = {Pahn, T. and Jonkman, J. and Rolges, R. and Robertson, A.},

abstractNote = {Physically measuring the dynamic responses of wind turbine support structures enables the calculation of the applied loads using an inverse procedure. In this process, inverse means deriving the inputs/forces from the outputs/responses. This paper presents results of a numerical verification of such an inverse load calculation. For this verification, the comprehensive simulation code FAST is used. FAST accounts for the coupled dynamics of wind inflow, aerodynamics, elasticity and turbine controls. Simulations are run using a 5-MW onshore wind turbine model with a tubular tower. Both the applied loads due to the instantaneous wind field and the resulting system responses are known from the simulations. Using the system responses as inputs to the inverse calculation, the applied loads are calculated, which in this case are the rotor thrust forces. These forces are compared to the rotor thrust forces known from the FAST simulations. The results of these comparisons are presented to assess the accuracy of the inverse calculation. To study the influences of turbine controls, load cases in normal operation between cut-in and rated wind speed, near rated wind speed and between rated and cut-out wind speed are chosen. The presented study shows that the inverse load calculation is capable of computing very good estimates of the rotor thrust. The accuracy of the inverse calculation does not depend on the control activity of the wind turbine.},

doi = {10.2514/6.2012-1735},

journal = {},

number = ,

volume = ,

place = {United States},

year = {2012},

month = {11}

}