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Modelling, survivability, assessment, and control of moored wave energy conversion systems
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Powering Our Lives With the Ocean: From Waves to Electricity
Full text linkWe are surrounded by an incredible amount of energy every day! Energy powers our phones, video games, and even our cars. But where does this energy come from? Did you know it can come from waves? All the waves that you see from the beach carry an enormous amount of clean energy, and we can turn this energy into electricity that powers our days. This is achieved by using devices called wave energy converters. Just like a windmill produces power thanks to the blowing wind, wave energy converters generate electricity by harnessing the energy from incoming waves. Curious to know how it works? Dive into this article and discover the world of wave energy
Input-Unknown Estimation for Arrays of Wave Energy Conversion Systems via LTI Synthesis
Full text linkThe incoming menace of global overheating and depletion of fossil fuels, highlight the need for alternative, renewable, energy sources. In this context, ocean wave energy has a massive potential to contribute towards global decarbonisation. In optimising wave energy converters (WEC) productivity, state-of-the-art, model-based optimal control techniques are fundamental to enhance energy absorption efficiency. However, the vast majority of these optimal approaches inherently require wave excitation force estimators. In particular, in array configurations, the interaction between WEC devices has to be taken into account to achieve a consistent excitation force estimation. In this paper, a linear time-invariant (LTI) estimation approach for a WEC farm is proposed. The technique proposed is based upon the so-called ‘simple and effective estimator’, recently presented in the WEC literature, which reformulates the wave excitation force estimation problem as a traditional tracking loop. The results show that the proposed approach provides accurate estimates of the exciting force for every device in the array, with almost no design effort, and mild computational requirements
Mooring System Design and Analysis for a Floating Offshore Wind Turbine in Pantelleria
Full text linkThe mooring system plays a key role in a floating offshore wind turbine: it connects the floating structure to its anchor on the seabed and it is designed to prevent the platform from drifting under the action of wind, waves and currents. The layout of the mooring system is strictly connected to the installation site: in the first place it depends on the bathymetry and the type of seabed which conditions the type of anchor that can be used; secondly by the wind and waves loads in extreme sea states.
To properly design the mooring system, three different configurations are proposed and discussed, respectively
adapting catenary, taut leg and semi-taut methodologies for a floating offshore wind turbine located near the island of Pantelleria, in Sicily. For each configuration, the Hexafloat foundation, developed by Saipem, is considered. Important design constraints such as how large the nominal sizes are, how long the mooring lines are, how far the anchor points are located, are demonstrated in detail. The material used will range from steel chains and wires to polyester ropes, to grant economically viable solutions
Perspectives on design of floating platforms for offshore airborne wind energy systems
Full text linkThe need for a fast transition towards electricity generation pushed large investments in highrisk, high-impact technologies such as floating Airborne Wind Energy Systems (AWES), which are expected to be highly cost efficient with respect to state-of-the-art offshore wind energy technology. Current research on the matter does not address the design challenge of a tailored floater, necessary to suit at most the unique features of such systems, and foster their industrial and commercial development. The goal of this study is to review the available solutions from traditional floating offshore wind energy systems, and hence to propose a straightforward concept, adapted from current designs, for the deployment of AWESs. Moreover, to provide
insights on how the geometrical parameters influence its motion response, a sensitivity study is performed, testing different design solutions against a wave scatter. In view of a cost-effective solution, a spar-like concept,
adapted to the specific needs of AWESs, is proposed. The sensitivity analysis suggests the need to adopt aspect ratio larger than 4 to effectively mitigate the pitch response; in addition, heave response emerges as a possible design constraint with large impact on the device’s costs
A Comparative study on basic design of hybrid storage architectures for grid-connected arrays of wave energy converters
No full textThe integration of Wave Energy Converters (WECs) into electrical grids remains a technical challenge due to the highly fluctuating nature of wave-induced power. Hybrid Energy Storage Systems (HESS), combining batteries and supercapacitors, offer a promising solution to mitigate power variability and ensure grid compliance. This study presents a modular approach for the preliminary design of HESS in WEC arrays, comparing centralised and decentralised storage configurations. A simplified wave-to-grid simulation model is employed, incorporating energy-maximising control strategies and a dual-filter power-smoothing scheme. Both control and storage systems are evaluated across multiple sea states and wave directions, providing a consistent comparison of sizing requirements. Results highlight that centralised layouts generally reduce total storage needs, particularly for supercapacitors, due to aggregation effects, though at the cost of reduced redundancy. The analysis underlines how resource variability and control strategy influence energy storage design and offers insights for the optimal deployment of WEC arrays with hybrid storage support
Control synthesis via Impedance-Matching in panchromatic conditions: a generalised framework for moored systems
No full textThis study focuses on addressing the challenge of integrating the tangled mathematical model of the mooring system into an effective control synthesis. The presented synthesis framework utilises the impedance-matching technique to achieve the desired controller performance by adapting the control parameters to align with the dynamic characteristics of the moored wave energy device. By leveraging this technique, the simulation framework provides a means to effectively incorporate the intricate mooring dynamics into the control synthesis process. Furthermore, this paper aims to delve into the concept of defining a representative control action by examining the input-exciting force of the feedback-controlled system. Through a straightforward case study, the authors demonstrate the significant impact of the mooring on the system dynamics and underscore the applicability of the proposed simulation framework. Moreover, the paper verifies the importance of considering the controlled system’s exciting input when addressing control synthesis, particularly in panchromatic conditions
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