On the principle of impedance-matching for underactuated wave energy harvesting systems

Faedo, Nicolás; Carapellese, Fabio; Pasta, Edoardo; Mattiazzo, Giuliana

doi:10.1016/j.apor.2021.102958

Cited by 37 publications

(33 citation statements)

References 30 publications

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“…the so-called 'reactive control', which is essentially a proportional-integral (PI) control structure K PI achieving impedance-matching (see e.g. [19,74]) at a (suitably selected) single interpolation frequency. To be precise, K PI : C → C, s → K PI (s), is defined as 13 Frequency-response mapping for the optimal control impedance (solid black), and each corresponding K PI (dotted), designed to interpolate I u at each considered peak period T w ∈ [2,4] where the set {θ 1 , θ 2 } ⊂ R can be uniquely selected to interpolate the so-called optimal control impedance I u , at a given interpolation frequency ω I (the reader is referred to "Appendix 3" for the explicit definition of the control impedance I u and the corresponding interpolation procedure).…”

Section: Performance Assessmentmentioning

confidence: 99%

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Optimal control of wave energy systems considering nonlinear Froude–Krylov effects: control-oriented modelling and moment-based control

et al. 2022

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Motivated by the relevance of so-called nonlinear Froude–Krylov (FK) hydrodynamic effects in the accurate dynamical description of wave energy converters (WECs) under controlled conditions, and the apparent lack of a suitable control framework effectively capable of optimally harvesting ocean wave energy in such circumstances, we present, in this paper, an integrated framework to achieve such a control objective, by means of two main contributions. We first propose a data-based, control-oriented, modelling procedure, able to compute a suitable mathematical representation for nonlinear FK effects, fully compatible with state-of-the-art control procedures. Secondly, we propose a moment-based optimal control solution, capable of transcribing the energy-maximising optimal control problem for WECs subject to nonlinear FK effects, by incorporating the corresponding data-based FK model via moment-based theory, with real-time capabilities. We illustrate the application of the proposed framework, including energy absorption performance, by means of a comprehensive case study, comprising both the data-based modelling, and the optimal moment-based control of a heaving point absorber WEC subject to nonlinear FK forces.

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Section: Performance Assessmentmentioning

confidence: 99%

“…The PI control structure in ( 59) is designed so as to interpolate the so-called optimal control impedance I u : C 0 → C, jω → I u ( jω), which can be simply defined [19,31] as…”

Section: Remark 30mentioning

confidence: 99%

Optimal control of wave energy systems considering nonlinear Froude–Krylov effects: control-oriented modelling and moment-based control

et al. 2022

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“…Figure 22b shows a picture of the experimental setup. The WECs were placed in a row layout, with an axis-to-axis separation distance equal to 1.20 m, equivalent to 2 D. Based on SID radiation tests, causal impedance matching proportional (P) and proportional-integral (PI) controllers were designed [70,71]. These controllers, corresponding to resistive and reactive control, respectively, were tested for a selection of irregular long-crested waves.…”

Section: The "Wecfarm" Wec Array Approachmentioning

confidence: 99%

Experimental Modelling of Point-Absorber Wave Energy Converter Arrays: A Comprehensive Review, Identification of Research Gaps and Design of the WECfarm Setup

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et al. 2022

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Commercial wave energy exploitation will be realised by placing multiple wave energy converters (WECs) in an array configuration. A point-absorber WEC consists of a floating or submerged body to capture wave energy from different wave directions. This point-absorber WEC acts as an efficient wave absorber that is also an efficient wave generator. Optimising the WEC array layout to obtain constructive interference within the WEC array is theoretically beneficial, whereas for wind farms, it is only important to avoid destructive interference within an array of wind turbines due to wake effects. Moreover, the WEC array layout should be optimised simultaneously with the applied control strategy. This article provides a literature review on the state of the art in physical modelling of point-absorber WEC arrays and the identification of research gaps. To cover the scientific gap of experimental data necessary for the validation of recently developed (nonlinear) numerical models for WEC arrays, Ghent University has introduced the “WECfarm” project. The identified research gaps are translated into design requirements for the “WECfarm” WEC array setup and test matrix. This article presents the design of the “WECfarm” experimental setup, consisting of an array of five generic heaving point-absorber WECs. The WECs are equipped with a permanent magnet synchronous motor (PMSM), addressing the need for WEC array tests with an accurate and actively controllable power take-off (PTO). The WEC array control and data acquisition are realised with a Speedgoat Performance real-time target machine, offering the possibility to implement advanced WEC array control strategies in the MATLAB-Simulink model. Wave basin testing includes long- and short-crested waves and extreme wave conditions, representing real sea conditions. Within the “WECfarm” project, two experimental campaigns were performed at the Aalborg University wave basin: (a) a testing of the first WEC in April 2021 and (b) a testing of a two-WEC array in February 2022. An experimental campaign with a five-WEC array is under preparation at the moment of writing.

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“…WEC represents the Wave Energy Converters, modeled with reference to the Pendulum Wave Energy Converter (PeWEC) device [44], using potential flow theory [45] and energy maximization control strategies [46]. The rated power of each device is 115 kWp, and its productivity was estimated from its power matrix and hourly sea state values off the coast of San Pietro, whose parameters were taken from the ERA5 database.…”

Section: Scenario Settingsmentioning

confidence: 99%

An Energy Cost Assessment of Future Energy Scenarios: A Case Study on San Pietro Island

et al. 2022

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The need for a clean and affordable energy supply is a major challenge of the current century. The tough shift toward a sustainable energy mix becomes even more problematic when facing realities that lack infrastructures and financing, such as small islands. Energy modeling and planning is crucial at this early stage of the ecological transition. For this reason, this article aims to improve an established long-run energy model framework, known as “OSeMOSYS,” with an add-on tool able to estimate different types of Levelized Cost Of Electricity (LCOE): a real and theoretical LCOE of each technology and a real and theoretical system LCOE. This tool fills a gap in most modeling frameworks characterized by a lack of information when evaluating energy costs and aims at guiding policymakers to the most appropriate solution. The model is then used to predict future energy scenarios for the island of San Pietro, in Sardinia, which was chosen as a case study. Four energy scenarios with a time horizon from 2020 to 2050—the Business-As-Usual (BAU) scenario, the Current Policy Projection (CPP) scenario, the Sustainable Growth (SG) scenario, and the Self-Sufficient-Renewable (SSR) scenario—are explored and ranked according to the efforts made in them to achieve an energy transition. Results demonstrates the validity of the tool, showing that, in the long run, the average LCOE of the system benefits from the installation of RES plants, passing from 49.1 €/MWh in 2050 in the BAU scenario to 48.8 €/MWh in the ambitious SG scenario. On the other hand, achieving carbon neutrality and the island’s energy independence brings the LCOE to 531.5 €/MWh, questioning the convenience of large storage infrastructures in San Pietro and opening up future work on the exploration of different storage systems.

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On the principle of impedance-matching for underactuated wave energy harvesting systems

Cited by 37 publications

References 30 publications

Optimal control of wave energy systems considering nonlinear Froude–Krylov effects: control-oriented modelling and moment-based control

Optimal control of wave energy systems considering nonlinear Froude–Krylov effects: control-oriented modelling and moment-based control

Experimental Modelling of Point-Absorber Wave Energy Converter Arrays: A Comprehensive Review, Identification of Research Gaps and Design of the WECfarm Setup

An Energy Cost Assessment of Future Energy Scenarios: A Case Study on San Pietro Island

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