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Structural Load Analysis of Floating Wind Turbines Under Blade Pitch System Faults

  • Rannam ChaabanEmail author
  • Daniel Ginsberg
  • Claus-Peter Fritzen
Chapter
Part of the Advances in Industrial Control book series (AIC)

Abstract

High performance and reliability are required for floating wind turbines due to the fact that they operate under hard conditions with minimum access for maintenance and high cost of repair. Therefore, the assessment of the severity of possible faults on the floating turbine structure will provide good guidelines once they occur either to employ the appropriate protective strategies such as turbine shutdown, or to continue power operation at reduced or full capacity. Furthermore, it will motivate the development of fault-oriented identification algorithms and fault-tolerant control systems that enhance the floating turbine reliability. As the pitch system has the highest failure rate, the faults of such system are of great interest. Several pitch system faults are considered and compared in this chapter including blade pitch sensor bias and gain faults, in addition to the performance degradation of the pitching mechanism, actuator stuck, and actuator runaway. Regardless of the origin of the fault inside the pitch system, these faults lead to an increased rotor imbalance which has different effects on the turbine structure and the platform motion. A utility-scale turbine mounted on the barge platform concept, and modeled using an aero-hydro-servo-elastic simulation tool is used to simulate these faults, and to study their effects as function of the fault magnitude and the mean wind speed in the full load region.

Keywords

Floating wind turbines Structural load analysis Pitch system faults Damage equivalent loading Fault modeling 

Nomenclature

β

Blade pitch angle

\(\beta_{\text{ref}}\)

Reference blade pitch angle

C

Damping coefficient

\(C_{{P,{ \hbox{max} }}}\)

Maximum power coefficient

e(t)

Error signal

\(\eta\)

Generator efficiency

h

Hub height

ID

Drive-train inertia

J

Turbine inertia term about platform pitch axis

K

Stiffness coefficient

KP

Proportional gain

KI

Integral gain

\(\lambda\)

Tip speed ratio

N

Gearbox ratio

\(\varOmega_{g}\)

Generator speed

\(\varOmega_{{g,{\text{rated}}}}\)

Rated generator speed

\(\varOmega_{r}\)

Rotor speed

\(\varOmega_{{r,{\text{rated}}}}\)

Rated rotor speed

\(\omega_{n}\)

Natural frequency

\(P_{\rm{rated}}\)

Rated output power of the generator

\(\frac{\delta P}{\delta \theta }\)

Sensitivity of the rotor aerodynamic power to the scheduling parameter

R

Rotor radius

\(\rho\)

Air density

T

Aerodynamic rotor thrust

\(T_{0}\)

Aerodynamic thrust over the rotor at the linearization point

\(T_{g}\)

Generator torque

\(t_{d}\)

Time delay

\(\theta\)

Scheduling parameter

V

Average wind speed over the rotor disk

w(t)

Noise

\(\dot{x}\)

Tower top (hub) velocity

\(\xi\)

Platform pitch angle

\(\dot{\xi }\)

Platform pitch angular velocity

\(\ddot{\xi }\)

Platform pitch angular acceleration

\(\zeta\)

Damping ratio

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Copyright information

© Springer International Publishing Switzerland 2014

Authors and Affiliations

  • Rannam Chaaban
    • 1
    Email author
  • Daniel Ginsberg
    • 2
  • Claus-Peter Fritzen
    • 1
  1. 1.Center of Sensor Systems (ZESS), Institute of Mechanics and Control Engineering-MechatronicsUniversity of SiegenSiegenGermany
  2. 2.Department of Mechanical Engineering, Institute of Mechanics and Control Engineering-MechatronicsUniversity of SiegenSiegenGermany

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