Numerical and experimental studies of excitation force approximation for wave energy conversion

Guo, Bingyong; Patton, Ron J.; Jin, Siya; Lan, Jianglin

doi:10.1016/j.renene.2018.03.007

Cited by 55 publications

(45 citation statements)

References 30 publications

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“…3(b)), the wave-to-excitation-force process is non-causal. Approximation approaches of the non-causal wave-toexcitation-force process were investigated numerically and experimentally in [30], [31], and a critical comparison of excitation force estimations is given in [32]. Hence, this paper only gives a brief overview of the excitation force approximation.…”

Section: Excitation Force Approximationmentioning

confidence: 99%

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Non-Linear Modeling of a Vibro-Impact Wave Energy Converter

Guo

Ringwood

2021

IEEE Trans. Sustain. Energy

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This paper proposes a non-linear vibro-impact mechanism, integrated inside a semi-submerged cylindrical buoy to form a self-contained and self-referenced vibro-impact wave energy converter (VIWEC), for performance enhancement. A non-linear mathematical model of the VIWEC is derived, considering linear wave-buoy interaction and non-linear vibro-impact mechanics. Numerical simulations are conducted to investigate the influence of the vibro-impact mechanism on the VIWEC's dynamics and performance. Numerical results conclude that the VIWEC is characterised by a band-pass frequency response and inherently decoupled from ocean waves of low frequencies, indicating high survivability under extreme sea states. The vibroimpact mechanism can also broaden the VIWEC's power capture bandwidth and limit the VIWEC's motion within its physical constraint. On the other hand, the VIWEC's dynamics are sensitive to design parameters, and an improper design may lead to rich and complex non-linear dynamics of the VIWEC, e.g. chaos and multi-stability. The proposed non-linear model can provide a platform for design optimisation and control development of the VIWEC.

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Section: Excitation Force Approximationmentioning

confidence: 99%

“…n is the approximation order. t c and n are selected by trial and error by evaluating the truncation error and the goodness of fit defined in [31]. In this study, t c = 3.2 s and n = 6 are used, and the identified excitation IRF is compared with its counterpart in Fig.…”

Section: Excitation Force Approximationmentioning

confidence: 99%

Non-Linear Modeling of a Vibro-Impact Wave Energy Converter

Guo

Ringwood

2021

IEEE Trans. Sustain. Energy

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“…In some cases, theoretical difficulties arise in investigating the response of floating WECs, especially when it comes to complex wave theories and non-linearities, therefore it would be more convenient to conduct such investigations in wave tank experiments. Guo, et al [80] compared three different methods to experimentally estimate the incoming wave forces on the buoy in order to optimize the control algorithms. In general, all these methods gave a good approximation of the wave excitation force, as their results were close to each other, but the more advanced approximation methods which require more inputs were found to be more appropriate for short waves with quickly varying conditions.…”

Section: Experimental Investigationmentioning

confidence: 99%

Point Absorber Wave Energy Harvesters: A Review of Recent Developments

2018

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Even though ocean waves around the world are known to contain high and dense amounts of energy, wave energy harvesters are still not as mature as other forms of renewable energy harvesting devices, especially when it comes to commercialization, mass production, and grid integration, but with the recent studies and optimizations, the point absorber wave energy harvester might be a potential candidate to stand out as the best solution to harvest energy from highly energetic locations around the world’s oceans. This paper presents an extensive literature review on point absorber wave energy harvesters and covers their recent theoretical and experimental development. The paper focuses on three main parts: One-body point absorbers, two-body point absorbers, and power take-offs. This review showcases the high amount of work being done to push point absorbers towards technological maturity to eventually kick off commercialization and mass production. It should also provide a good background on the recent status of point absorber development for researchers in the field.

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“…The proposed estimator requires numerous pressure transducers, which might exacerbate the computational complexity of the estimator. An estimation technique based on floater hull pressure measurements along with the floater's heave displacement and acceleration measurements is introduced in [7]. The reported method lacks an explicit mechanism to handle measurement noise.…”

Section: Introductionmentioning

confidence: 99%

“…The method generally produced satisfactory results in nominal condition; however, the performance deteriorated significantly when parameter perturbations were applied. Another UIO technique, in which only the position measurement is required, has been reported in [7]. The method uses a linearized model of the WEC, and a linear matrix inequality (LMI) formulation of the H ∞ optimization technique -previously deployed in [11] -is used in an attempt to minimize the effect of the derivative operator on the estimation accuracy.…”

Section: Introductionmentioning

confidence: 99%

Wave Excitation Force Estimation Using an Electrical-Based Extended Kalman Filter for Point Absorber Wave Energy Converters

2020

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Accurate real-time knowledge of the wave excitation force affecting a wave energy converter (WEC)-either through measurement or by estimation-is crucial for implementing effective control strategies that ensure optimum power absorption, system reliability, and durability. The estimation of the excitation force using other readily available measurements is deemed a cost-effective solution given the technical difficulties associated with directly measuring the excitation force on the WEC's floater hull. In this study, an electrical-based extended Kalman filter (E-EKF) estimator for estimating the wave excitation force, floater's heave displacement, and velocity is proposed. The estimator is derived using a holistic nonlinear wave-to-wire model of a direct-drive heaving WEC. A continuous and differentiable approximation of the well-known Tustin friction model is utilized to incorporate the friction force model into the estimator. The proposed E-EKF estimator requires only the measurement of the three-phase permanent magnet linear generator stator currents using current transducers. A practical approach is provided to overcome the need for measuring the wave surface elevation and velocity. Simulations are conducted to assess the goodness of the proposed E-EKF under various sea-state conditions, modeling mismatches, and electric loading scenarios. For the sake of comparison, the performance of the E-EKF estimator is measured against mechanical-based extended Kalman filter and linearized mechanical Kalman filter estimators. The E-EKF estimator exhibits superior performance in terms of nearly all performance metrics, with an excitation energy percentage error score not exceeding 9 %, while being immune to measurement noise.

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Numerical and experimental studies of excitation force approximation for wave energy conversion

Cited by 55 publications

References 30 publications

Non-Linear Modeling of a Vibro-Impact Wave Energy Converter

Non-Linear Modeling of a Vibro-Impact Wave Energy Converter

Point Absorber Wave Energy Harvesters: A Review of Recent Developments

Wave Excitation Force Estimation Using an Electrical-Based Extended Kalman Filter for Point Absorber Wave Energy Converters

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