The applicants are interested in establishing a collaboration aimed at the production of a joint paper. Such collaboration will be based on exploring the possibility of extending some control techniques already proposed for point absorbers devices to the ISWEC Wave Energy Converter developed at the Politecnico di Torino. The ISWEC (Inertial Sea Wave Energy Converter) is a system converting wave power into electrical power thanks to the inertial effects produced from a gyroscope. The ISWEC is composed of a floating body with a slack mooring to the seabed. The waves energize the float with a pitching motion that is transmitted to the gyroscopic system that responds with a precession motion used to direct drive the electric generator. Due to the substantial analogy between ISWEC dynamic equations and the ones describing the behaviour of a point absorber in heave it seems promising to apply the techniques developed from Dr. Tedeschi to optimize the PTO usage in order to improve the power extraction while limiting the PTO rated power and thus its cost. More specifically, an adaptive control strategy based on the maximization of the averaged power extraction under the main actual electro and/or mechanical constraints acting in the system will be investigated. The project will be developed remotely from December 2010, but it will include as a main core a one-week visit of Dr. Elisabetta Tedeschi to the Politecnico di Torino (host institution of Dr. Giovanni Bracco), where the ISWEC prototype is available, in order to personally discuss technical issues and finalize the paper preparation.
Publication at EWTEC 2011:
Control Strategies for the ISWEC Wave Energy System
Giovanni Bracco1, Ermanno Giorcelli1, Giuliana Mattiazzo1, Elisabetta Tedeschi2 and Marta Molinas2
1: Politecnico di Torino, Italy
2: Norwegian University of Science and Technology, Trondheim, Norway
Abstract: The control of the motion field of a Wave Energy Converter (WEC) is a key factor for its wave power extraction capabilities. The goal of this paper is the optimization of the power performance of the ISWEC Wave Energy System. The ISWEC is a WEC exploiting the precession of a gyroscopic system to drive the Power Take-Off (PTO). The control of the device aims at exploiting all the available control parameters in order to maximize the extracted power. At first the tuning of PTO stiffness in addition to PTO damping is analysed and then the additional control degree provided by the gyro speed is exploited, too. Application of multi-parameter control strategies, especially when including a reactive component, can however be highly demanding from both the mechanical and electrical standpoint. In order to obtain a sustainable operative condition for the system it is necessary that applied control avoids excessive oscillation and velocity of the device and respect the PTO power and torque limitations as well. In this paper a control strategy that inherently takes into account such limitations and consequently adapts based on the incident waves proves to significantly improve the system performance. In order to test such an adaptive control technique an ISWEC device with rated power of 3 kW and working in the Alghero site is here considered and tested with different floater configurations to derive convenient design trade-off for the considered application.
- Contact information
- Bracco Giovanni and Elisabetta Tedeschi
- Contact email
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