Wave flume testing of an oscillating-body wave energy converter with a tuned inerter

Sugiura, Keita; Sawada, Ryoko; Nemoto, Yudai; Haraguchi, Ruriko; Asai, Takahiro

doi:10.1016/j.apor.2020.102127

Cited by 31 publications

(17 citation statements)

References 26 publications

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“…In addition, algorithms to control the stiffness and damping of the PTO system with regard to the change of the sea state are desired. Furthermore, experimental investigation [39] to assess the feasibility of the device under real sea condition is required. This includes the consideration of locking the PTO system in survival mode and understanding the buoy response to highly non-linear extreme waves.…”

Section: Discussionmentioning

confidence: 99%

Enhanced power absorption of a point absorber wave energy converter using a tuned inertial mass

Haraguchi¹,

Asai²

2020

Preprint

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A novel point absorber wave energy converter with a tuned inertial mass (TIM), which is capable of significantly increasing the energy absorption and broadening the effective bandwidth, is proposed in this paper. The mechanism of the TIM has originally been introduced in the field of civil engineering as a passive energy absorber for structures subjected to external loadings such as earthquakes. It relies on attaching an additional tuning spring and a rotational inertial mass to the primary system, to improve the energy absorption performance by amplifying the displacement of the damper. Thus, considering typical point absorbers modeled as a mass-spring-dashpot system similar way to civil structures, the application of the TIM to wave energy converters can be expected to have a significant effect. In this paper, numerical investigation on the power generation performance of a point absorber with the TIM is conducted under random sea waves. The amplitude response and power generation performance are compared with the conventional point absorber, considering both non-resonant and resonant buoy cases. It is shown that by properly designing the tuning spring stiffness and generator damping, the rotation of the generator can be amplified compared to the buoy, increasing the power absorption drastically.

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Section: Discussionmentioning

confidence: 99%

Enhanced power absorption of a point absorber wave energy converter using a tuned inertial mass

Haraguchi¹,

Asai²

2020

Preprint

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“…To improve the power generation performance of a conventional singlebody point absorber WEC, which has one floating buoy, the authors employed a tuned inerter mechanism [14,15]. Originally, the tuned inerter mechanism was proposed by [16] as a structural control device to absorb vibration energy effectively from vibrating civil structures such as buildings induced by seismic disturbances and to mitigate damage.…”

Section: Introductionmentioning

confidence: 99%

“…The authors employed a generator or a motor as the linear damping element in the tuned inerter mechanism and showed that the mechanism enhances the ability to extract energy from vibrating structures at a low frequency of less than 10 Hz [18,19]. In addition, the authors proposed a single-body point absorber WEC with a tuned inerter and the efficacy of the present device was shown through numerical simulation studies [14] and wave flume testing using a small-scale prototype model [15]. However, generally, the single-body point absorber WEC needs to be connected directly to the ocean floor.…”

Section: Introductionmentioning

confidence: 99%

Numerical evaluation of a two-body point absorber wave energy converter with a tuned inerter

Asai

Sugiura

2021

Renewable Energy

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To increase the amount of energy captured from a vibrating buoy in the ocean with a simple mechanism, this paper proposes a two-body point absorber wave energy converter (WEC) with a tuned inerter. The tuned inerter mechanism consists of a spring, a linear damping element, and a component called inerter. This mechanism was originally proposed in the field of civil engineering as a structural control device which can absorb energy from vibrating structures effectively by taking advantage of the resonance effect of the inerter part. In addition to this mechanism where a generator is used as the linear damping element, the current of the generator for the power take-off system is controlled based on the algorithms proposed in literature to achieve further improvement of the power generation capability. In this research, a detailed analytical model of the proposed WEC is introduced and developed. Then the power generation performances of full-scale WEC models are assessed through numerical simulation studies using WAMIT software and it is shown that the current-controlled WEC with the proposed mechanism achieves an 88% increase compared to the conventional one for the JONSWAP spectrum with 6 s peak period and 1 m significant wave height.

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“…A self-sensing harvester, which measures temperature [3], displacement [4], and body motions [5] without the use of specific sensors and batteries, has also been proposed for advanced applications. Transducers for vibration energy harvesting include tuned mass dampers [6,7], magnetorheological elastomers [8], electromagnetic devices [9,10], electrets [11,12], magnetostrictive elements [13][14][15], and piezoelectric elements [16]. Piezoelectric transducers convert mechanical energy into electrical energy and vice versa as direct and inverse piezoelectric effects [17,18].…”

Section: Introductionmentioning

confidence: 99%

Adaptive and Robust Operation with Active Fuzzy Harvester under Nonstationary and Random Disturbance Conditions

Hara

Otsuka

Makihara

2021

Sensors

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The objective of this paper is to amplify the output voltage magnitude from a piezoelectric vibration energy harvester under nonstationary and broadband vibration conditions. Improving the transferred energy, which is converted from mechanical energy to electrical energy through a piezoelectric transducer, achieved a high output voltage and effective harvesting. A threshold-based switching strategy is used to improve the total transferred energy with consideration of the signs and amplitudes of the electromechanical conditions of the harvester. A time-invariant threshold cannot accomplish effective harvesting under nonstationary vibration conditions because the assessment criterion for desirable control changes in accordance with the disturbance scale. To solve this problem, we developed a switching strategy for the active harvester, namely, adaptive switching considering vibration suppression-threshold strategy. The strategy adopts a tuning algorithm for the time-varying threshold and implements appropriate intermittent switching without pre-tuning by means of the fuzzy control theory. We evaluated the proposed strategy under three realistic vibration conditions: a frequency sweep, a change in the number of dominant frequencies, and wideband frequency vibration. Experimental comparisons were conducted with existing strategies, which consider only the signs of the harvester electromechanical conditions. The results confirm that the presented strategy achieves a greater output voltage than the existing strategies under all nonstationary vibration conditions. The average amplification rate of output voltage for the proposed strategy is 203% compared with the output voltage by noncontrolled harvesting.

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Wave flume testing of an oscillating-body wave energy converter with a tuned inerter

Cited by 31 publications

References 26 publications

Enhanced power absorption of a point absorber wave energy converter using a tuned inertial mass

Enhanced power absorption of a point absorber wave energy converter using a tuned inertial mass

Numerical evaluation of a two-body point absorber wave energy converter with a tuned inerter

Adaptive and Robust Operation with Active Fuzzy Harvester under Nonstationary and Random Disturbance Conditions

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