Influence of hydraulic power take-off unit parameters on power capture ability of a two-raft-type wave energy converter

Liu, Changhai; Yang, Qingjun; Bao, Gang

doi:10.1016/j.oceaneng.2017.12.063

Cited by 41 publications

(23 citation statements)

References 16 publications

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“…A boost pump is also added in the PTO system to provide the extra fluid flow to the hydraulic motor through check valves during a small hydraulic chamber (rod chamber) operation of a hydraulic actuator. This concept also has been used in attenuator type WEC devices such as Pelamis; however, a different configuration of the actuation module was used because of the different operation of this WEC device as described in [88][89][90].…”

Section: Constant-pressure Hydraulic Pto Based On Four-check Valves Cmentioning

confidence: 99%

Hydraulic Power Take-Off Concepts for Wave Energy Conversion System: A Review

et al. 2019

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Ocean wave energy is one of the most abundant energy sources in the world. There is a wide variety of wave energy conversion systems that have been designed and developed, resulting from the different ways of ocean wave energy absorption and also depending on the location characteristics. This paper reviews and analyses the concepts of hydraulic power take-off (PTO) system used in various types of wave energy conversion systems so that it can be a useful reference to researchers, engineers and inventors. This paper also reviews the control mechanisms of the hydraulic PTO system in order to optimise the energy harvested from the ocean waves. Finally, the benefits and challenges of the hydraulic PTO system are discussed in this paper.

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Section: Constant-pressure Hydraulic Pto Based On Four-check Valves Cmentioning

confidence: 99%

Hydraulic Power Take-Off Concepts for Wave Energy Conversion System: A Review

et al. 2019

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“…(iii) Nonlinear mechanisms have been shown to enhance the bandwidth of high performance of wave energy devices [23,24]. (iv) Flexibility of the absorber may positively contribute (in some cases significantly) to the efficiency of wave energy harnessing devices [25], and (v) optimized geometry, shape, and power take-off mechanism of a wave energy converter play an important role in the overall performance of the device [26][27][28][29][30]. Shape optimization is of relevance in all classes of wave energy conversion techniques such as oscillating water columns where it is found that immersion depth of 0.45 of water depth and chamber diameter of 0.92 of water depth yields the maximum efficiency [31]; and overtopping devices where it is found that the optimum length to opening ratio has to be ∼ 2.5 − 3 [32].…”

Section: Introductionmentioning

confidence: 99%

Shape optimization of wave energy converters for broadband directional incident waves

Esmaeilzadeh

Alam

2019

Ocean Engineering

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Here, through a systematic methodology and the use of high performance computing, we calculate the optimum shape for a wave energy converter under the action of incident waves of (i) monochromatic unidirectional, (ii) monochromatic directional, (iii) polychromatic unidirectional and (iv) polychromatic directional (with both directional symmetry and asymmetry). As a benchmark for our study, without loss of generality, we consider a submerged planar pressure differential wave energy converter, and use Genetic Algorithm to search through a wide range of shapes. A new parametric description of absorber shape based on Fourier decomposition of geometrical shapes is introduced, and for each shape hydrodynamic coefficients are calculated, optimum power take-off parameters are obtained, and overall efficiency is determined. We show that an optimum geometry of the absorber plate can absorb a significantly higher energy (in some cases few times higher) when compared to a circular shape of the same area. Specifically, for a unidirectional incident wave, the optimum shape, as expected, is obtained to be the most elongated shape. For directional incident waves, a butterfly-shape is the optimum geometry whose details depend on not only the amplitude and direction of incident wave components, but also the relative phases of those components. For the latter effect, we find an optimally averaged profile through a statistical analysis.

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“…Although the dynamic characteristics of the analogous HPTO have been studied in Pelamis [10], Wavestar [19], the two-raft-type WEC [16] and so on, the operational stability of HPTO have not been researched deeply. Practically, the existences of the highpressure accumulator, flow control valve and oil tank all have favourable impacts on the stability [28].…”

Section: Introductionmentioning

confidence: 99%

“…Orer and Ozdamar [14] and Zhang et al [15] analysed and optimised the parameters for the high‐pressure accumulator. Furthermore, Liu et al [16] systematically researched the influence of the parameters of the hydraulic cylinder, high‐pressure accumulator, hydraulic motor and generator on the capture width ratio. Ricci et al [17] added control accumulators between a cylinder and four check valves to increase the power generation.…”

Section: Introductionmentioning

confidence: 99%

“…Schematic diagram of the experimental platform. (1)a pump station, (2) a directional control valve, (3) five pressure gages, (4) two single-acting single-rod hydraulic cylinders, (5) a double-acting double-rod hydraulic cylinder, (6) two tension pressure sensors, (7) a displacement sensor, (8) four check valves, (9) three pressure sensors, (10) three three-way valves, (11) a flow control valve,(12) four flow sensors,(13) an overflow valve,(14) two stop valves, (15) a high-pressure accumulator,(16) a temperature sensor,(17) a viscosity sensor,(18) a hydraulic motor,(19) a generator,(20) a rotational speed sensor, (21) a torque sensor,(22) an oil tank Physical structure of the experiment platform…”

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confidence: 99%

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Dynamic performance of key components for hydraulic power take‐off of the wave energy converter

Chen

Wen

Yue

et al. 2019

IET Renewable Power Generation

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Since the input power of the real waves varies continuously and periodically, how to stabilise the operation and generation during wave energy utilisation has become an inevitable and significant topic. This study focuses on the wave energy converter of a hydraulic power takeoff (HPTO) connected to a pendulum and studies the influences of the key components, i.e. the high-pressure accumulator, oil tank and flow control valve, on the operational stability of HPTO by simulations and experiments. Parameters of the high-pressure accumulator are analysed and optimised. The dynamic performance of the HPTO with or without the oil tank is also investigated. Besides, the functions of the flow control valve in the cases of excessive input power and load shedding are given. Results show that the key components play very important roles in the operational stability of HPTO. Reasonable configurations of the high-pressure accumulator and oil tank are significant to improve the quality of output power and stability. Appropriate actions of the flow control valve are beneficial to protection and stability. Therefore, these key components should be considered preferentially during the design of HPTO.

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Influence of hydraulic power take-off unit parameters on power capture ability of a two-raft-type wave energy converter

Cited by 41 publications

References 16 publications

Hydraulic Power Take-Off Concepts for Wave Energy Conversion System: A Review

Hydraulic Power Take-Off Concepts for Wave Energy Conversion System: A Review

Shape optimization of wave energy converters for broadband directional incident waves

Dynamic performance of key components for hydraulic power take‐off of the wave energy converter

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