Ringwood, John and Ermakov, Andrei (2022) ENERGY-MAXIMISING CONTROL PHILOSOPHY FOR A CYCLOROTOR WAVE ENERGY DEVICE. Proceedings of the ASME 2022 41st International Conference on Ocean, Offshore and Artic Engineering.

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Abstract

Recently, cyclorotors, utilizing lift rather than buoyancy forces for energy extraction, have been proposed and inherit many of the appealing features characteristic of modern wind turbines. In particular, the ability to spill energy though foil pitching allows the device to remain at rated power despite significant variations in input power level, while additional cyclorotor features, including variable submergence depth and rotor radius, also permit a significant degree of modulation of the device structure, and energy absorption characteristics, offering considerable flexibility. These configuration flexibilities, in addition to torque control of the rotor/generator shaft (also characteristic of wind turbines) offers the control engineer considerable freedom in adjusting the device characteristics to maximise the effectiveness of the device in capturing wave power, while maintaining structural integrity and minimizing harmful stresses on system components. However, such flexibility also provides a significant challenge in the form of a multivariable control problem for a system described by significantly nonlinear hydrodynamics. This paper describes a proposed hierarchical control system for a cyclorotor wave energy device, utilizing submergence depth, rotor radius, foil pitch angles, and shaft torque as control inputs. The hierarchy involves the separation of the control actuators into two classes: structural (or slow) control effectors, and wave-by-wave (or fast) control effectors. In particular, the paper will examine the interaction between the two levels of the control hierarchy and the need, if any, for simultaneous optimisation of the control parameters at both levels.

Item Type:	Article
Keywords:	enewable energy; wave energy converter; control system; cyclorotor; hierarchical control; LiftWEC; lift-based wave energy converter;
Academic Unit:	Faculty of Science and Engineering > Electronic Engineering Faculty of Science and Engineering > Research Institutes > Centre for Ocean Energy Research
Item ID:	16314
Depositing User:	Professor John Ringwood
Date Deposited:	15 Jul 2022 08:19
Journal or Publication Title:	Proceedings of the ASME 2022 41st International Conference on Ocean, Offshore and Artic Engineering
Publisher:	ASME
Refereed:	Yes
URI:	Organisation
Use Licence:	This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

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