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Optimization of floating current turbines
Citation Link: https://doi.org/10.15480/882.4498
Publikationstyp
Doctoral Thesis
Date Issued
2022
Sprache
English
Author(s)
Advisor
Referee
Title Granting Institution
Technische Universität Hamburg
Place of Title Granting Institution
Hamburg
Examination Date
2022-06-20
Institut
TORE-DOI
Citation
Technische Universität Hamburg (2022)
This dissertation documents and explains the development and optimization of a floating-type tidal current turbine system that is capable to improve the power output in underrated inflow conditions by induced motion. The motion is induced by the floating platform on which the turbine is mounted. Two motion patterns are considered in the work: the one-dimensional sway motion and the motion flying on the spherical surface defined by the tether.
A tandem counter-rotating turbine is used as the turbine model. The in-house panel method code \textit{pan}MARE is applied to develop the full-scale turbine model and to derive the coefficients for the following dynamic simulations. And the interactions between the two tandem rotors in the turbine is simulated by the multi-solver method. Due to the different motion patterns, two platforms are developed accordingly. Each platform consists of a hydrofoil system for the motion drive, a hull to house equipment and a cross-form rudder system to maintain heading and provide control moments. The hydrodynamic coefficients of these components are derived primarily from analytical and empirical equations.
An equation of motion system is developed to carry out dynamic simulations. A control system is built to manoeuvre the platform for flying motion in 6-DOF. A controller is developed with the control law extended from the integrator backstepping algorithm with the consideration of a constant tidal current flow, which is compared with a proportional-derivative controller. The attitude of the platform is the objective of the controller, making the Euler angles the control input. On top of the controller, a simple guidance system was built, replacing the non-intuitive Euler angles with a heading angle as input. In addition, the guidance system tries to reduce the drift of the platform. After the control moments are given by the control law, the desired moments are converted into the deflection angles of the control surfaces by a control allocation system.
Dynamic simulations are carried out to validate the performance of the platforms. Both platforms are capable of operating in either stationary or induced motion conditions, and the motion does increase the power output. The platform in flying motion outperforms the other platform in terms of static stability and power fluctuations. The performance of the control system has also been verified.
A tandem counter-rotating turbine is used as the turbine model. The in-house panel method code \textit{pan}MARE is applied to develop the full-scale turbine model and to derive the coefficients for the following dynamic simulations. And the interactions between the two tandem rotors in the turbine is simulated by the multi-solver method. Due to the different motion patterns, two platforms are developed accordingly. Each platform consists of a hydrofoil system for the motion drive, a hull to house equipment and a cross-form rudder system to maintain heading and provide control moments. The hydrodynamic coefficients of these components are derived primarily from analytical and empirical equations.
An equation of motion system is developed to carry out dynamic simulations. A control system is built to manoeuvre the platform for flying motion in 6-DOF. A controller is developed with the control law extended from the integrator backstepping algorithm with the consideration of a constant tidal current flow, which is compared with a proportional-derivative controller. The attitude of the platform is the objective of the controller, making the Euler angles the control input. On top of the controller, a simple guidance system was built, replacing the non-intuitive Euler angles with a heading angle as input. In addition, the guidance system tries to reduce the drift of the platform. After the control moments are given by the control law, the desired moments are converted into the deflection angles of the control surfaces by a control allocation system.
Dynamic simulations are carried out to validate the performance of the platforms. Both platforms are capable of operating in either stationary or induced motion conditions, and the motion does increase the power output. The platform in flying motion outperforms the other platform in terms of static stability and power fluctuations. The performance of the control system has also been verified.
DDC Class
600: Technik
620: Ingenieurwissenschaften
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