Wave absorber ballast optimization based on the analytical model for a pitching wave energy converter

Temiz, Irina; Ekweoba, Chisom; Thomas, Sarah; Kramer, Morten; Savin, Andrej

doi:10.1016/j.oceaneng.2021.109906

Cited by 6 publications

(1 citation statement)

References 24 publications

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“…Finally, in recent years, Têtu et al [11] installed a negative spring mechanism on the Wavestar setup to shift the resonance period. Temiz et al [12] changed the ballast inertia moment by altering ballast compartment locations and mass properties, so as to achieve different resonance frequencies of a pitching WEC. In recent studies, movable mass methods have been introduced to solo Duck WECs [13] or inverse pendulum-type wave energy converters [14][15][16][17] in order to achieve hydrostatic stiffness adjustment and resonant energy capture.…”

Section: Introductionmentioning

confidence: 99%

Implementation Process Simulation and Performance Analysis for the Multi-Timescale Lookup-Table-Based Maximum Power Point Tracking under Variable Irregular Waves

Yue,

Meng,

Tong

et al. 2023

Energies

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The efficacy of the multi-timescale lookup-table-based maximum power point tracking (MLTB MPPT) in capturing energy at various fixed sea states has already been demonstrated. However, it remains imperative to conduct a more comprehensive evaluation of the MPPT tracking performance under varying sea states in practical scenarios. Additionally, it is crucial to engage in an in-depth analysis of the dynamic process and energy loss/consumption associated with MLTB MPPT implementations. This paper focuses on the implementation process simulation and performance analysis for the MLTB MPPT under variable irregular waves. Firstly, the structure of the wave power controller based on a MLTB MPPT algorithm is described in detail, as well as that of a controlled plant, known as a novel inverse-pendulum wave energy converter (NIPWEC). Secondly, mathematical models for the MLTB MPPT are developed, taking into account the efficiency of each link. In this paper, we present simplified modelling methods for both permanent magnet synchronous generator (PMSG) vector control and permanent magnet synchronous motor (PMSM) servo control. Finally, the tracking performance of the MLTB MPPT in the presence of variable irregular waves is comprehensively analyzed by simulating the implementation process and comparing it with two other MPPT algorithms, i.e., the frequency- and amplitude-control-based MPPT and the lookup-table-based internal mass position adjustment combined with the optimal fixed damping search. Results show that the MLTB MPPT (Method 2) is a competitive algorithm. Besides, a significant portion (>12%) of the time-averaged absorbed power is actually lost during the power generation process. On the other hand, the power required for a mass-position-adjusting mechanism is relatively small (approximately 0.2 kW, <1.5%). The research findings can offer theoretical guidance for optimizing the operation of NIPWEC engineering prototypes under actual sea conditions.

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