Environmental Engineering Reference
In-Depth Information
Chapter 11
Structural Load Analysis of Floating
Wind Turbines Under Blade Pitch System
Faults
Rannam Chaaban, Daniel Ginsberg and Claus-Peter Fritzen
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 con-
cept, 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
