Wave energy plants: Control strategies for avoiding the stalling behaviour in the Wells turbine

Amundarain, Modesto; Alberdi, Mikel; Garrido, Aitor J.; Garrido, Izaskun; Maseda, Javier

doi:10.1016/j.renene.2010.04.009

Cited by 55 publications

(19 citation statements)

References 17 publications

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“…The wells turbine is designed in such a way that it converts bidirectional air flow into unidirectional rotatory motion which drives the generator [26][27][28][29].…”

Section: Wells Turbinementioning

confidence: 99%

“…The d-q equivalent generator model has been considered in this paper [27,30]. The mathematical equations of the stator and rotor voltages are:…”

Section: Wound Rotor Induction Generator Equationsmentioning

confidence: 99%

“…Now, in Equation (13), replacing R r by (R r + R ext ) and putting V dr = 0 gives: From Equations (7)- (27), the expression for flow coefficient can be written as:…”

Section: Performance Indexmentioning

confidence: 99%

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Maximizing Output Power in Oscillating Water Column Wave Power Plants: An Optimization Based MPPT Algorithm

2018

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This paper proposes an optimization based maximum power point tracking (MPPT) algorithm for selection of appropriate external rotor resistances of wound rotor induction generator (WRIG). The generator coupled with a Wells turbine is used in oscillating water column (OWC) wave power plants. The Wells turbine suffers with stalling behaviour that reduces the average output power significantly. Hence, the objective is to prevent aerodynamic stalling of the Wells turbine and hence maximizing the output power simultaneously. But inappropriate selection of rotor resistance leads to excessive power loss. Therefore, two approaches have been applied: (i) the rotor resistance values are selected manually by trial and error method or non-optimized approach (ii) a performance index has been derived and minimized using particle swarm optimization technique to obtain the optimized values of rotor resistance. Simulation results have been performed for turbine efficiency, output power and power loss in external rotor resistance. Finally, the proposed control approach is illustrated for two particular cases of regular and irregular waves.

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“…The wells turbine is designed in such a way that it converts bidirectional air flow into unidirectional rotatory motion which drives the generator [26][27][28][29].…”

Section: Wells Turbinementioning

confidence: 99%

“…The d-q equivalent generator model has been considered in this paper [27,30]. The mathematical equations of the stator and rotor voltages are:…”

Section: Wound Rotor Induction Generator Equationsmentioning

confidence: 99%

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Maximizing Output Power in Oscillating Water Column Wave Power Plants: An Optimization Based MPPT Algorithm

2018

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“…This reduced rating for the frequency converter implies an important cost saving, compared with a fully rated converter [40,41]. It works as a motor when running below synchronous speed, and as a generator above synchronous speed.…”

Section: Operation Cyclementioning

confidence: 99%

“…Two control strategies of an OWC-W-T generator module are proposed and compared in order to study the stalling behavior in the W-T by [41]. In the first one, a rotational speed control system is employed to appropriately adapt the speed of the double-fed induction generator coupling to the turbine, according to the pressure drop entry.…”

Section: Electricity Generationmentioning

confidence: 99%

Wells turbine for wave energy conversion: a review

Shehata

Xiao

Saqr

et al. 2016

Int. J. Energy Res.

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Summary In the past 20 years, the use of wave energy systems has significantly increased, generally depending on the oscillating water column concept. Wells turbine is one of the most efficient oscillating water column technologies. This article provides an updated and a comprehensive account of the state‐of‐the‐art research on Wells turbine. Hence, it draws a roadmap for the contemporary challenges, which may hinder future reliance on such systems in the renewable energy sector. In particular, the article is concerned with the research directions and methodologies, which aim at enhancing the performance and efficiency of Wells turbine. The article also provides a thorough discussion of the use of CFD for performance modeling and design optimization of Wells turbine. It is found that a numerical model using the CFD code can be employed successfully to calculate the performance characteristics of W‐T as well as other experimental and analytical methods. The increase of research papers about CFD, especially in the last 5 years, indicates that there is a trend that considerably depends on the CFD method. Copyright © 2016 John Wiley & Sons, Ltd.

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Numerical optimization of axial turbine with self-pitch-controlled blades used for wave energy conversion

Mohamed

Shaaban

2013

Int. J. Energy Res.

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SUMMARY Wells turbines are among the most practical wave energy converters despite their low aerodynamic efficiency and power produced. It is proposed to improve the performance of Wells turbines by optimizing the blade pitch angle. Optimization is implemented using a fully automated optimization algorithm. Two different airfoil geometries are numerically investigated: the standard NACA 0021 and an airfoil with an optimized profile. Numerical results show that each airfoil has its own optimum blade pitch angle. The present computational fluid dynamics optimization results show that the optimum blade pitch angle for NACA 0021 is +0.3° while that of the airfoil with an optimized profile equals +0.6°.The performance of the investigated airfoils is substantially improved by setting the blades at the optimum blade pitch angle. Both the turbine efficiency and tangential force coefficient are improved, especially at low flow rate and during turbine startup. Up to 4.3% average increase in turbine efficiency is achieved by optimizing the blade pitch angle. A slight improvement of the tangential force coefficient and decrease of the axial force coefficient are also obtained. A tangible increase of the stall‐free operating range is also achieved by optimizing the blade pitch angle. Copyright © 2013 John Wiley & Sons, Ltd.

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Wave energy plants: Control strategies for avoiding the stalling behaviour in the Wells turbine

Cited by 55 publications

References 17 publications

Maximizing Output Power in Oscillating Water Column Wave Power Plants: An Optimization Based MPPT Algorithm

Maximizing Output Power in Oscillating Water Column Wave Power Plants: An Optimization Based MPPT Algorithm

Wells turbine for wave energy conversion: a review

Numerical optimization of axial turbine with self-pitch-controlled blades used for wave energy conversion

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