Comparison of Direct-Drive Power Takeoff Systems for Ocean Wave Energy Applications

Rhinefrank, Ken; Schacher, Al; Prudell, Joseph; Brekken, Ted K. A.; Stillinger, Chad; Yen, John Z.; Ernst, Steven G.; Jouanne, Annette von; Amon, Ean; Paasch, Robert; Brown, Adam; Yokochi, Alex

doi:10.1109/joe.2011.2173832

Cited by 59 publications

(28 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Energies 2017, 10, 114 2 of 15 an attractive technology with advantages of reduced complexity, reduced maintenance and system cost [5][6][7][8][9][10][11][12][13]. At the same time, appropriate control and power conversion methods need to be developed for linear wave energy converters, to increase the efficiency of electrical power extraction and conversion.…”

Section: Introductionmentioning

confidence: 99%

“…Traditional point absorbing wave energy converters employ either a linear electric generator or a linear-to-rotary mechanism. Rack-pinion, slider-crank or ball-screw mechanisms are usually employed in linear-to-rotary systems [8]. Among the linear-to-rotary mechanisms, the ball-screw mechanism is useful in transforming a slow linear motion into a fast rotary motion with a high efficiency (more than 90%), and this is suitable for use in point absorbing wave energy converters [14,15].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Designing and Testing Composite Energy Storage Systems for Regulating the Outputs of Linear Wave Energy Converters

Nie

Xiao

Hiralal³

et al. 2017

Energies

View full text Add to dashboard Cite

Linear wave energy converters generate intrinsically intermittent power with variable frequency and amplitude. A composite energy storage system consisting of batteries and super capacitors has been developed and controlled by buck-boost converters. The purpose of the composite energy storage system is to handle the fluctuations and intermittent characteristics of the renewable source, and hence provide a steady output power. Linear wave energy converters working in conjunction with a system composed of various energy storage devices, is considered as a microsystem, which can function in a stand-alone or a grid connected mode. Simulation results have shown that by applying a boost H-bridge and a composite energy storage system more power could be extracted from linear wave energy converters. Simulation results have shown that the super capacitors charge and discharge often to handle the frequent power fluctuations, and the batteries charge and discharge slowly for handling the intermittent power of wave energy converters. Hardware systems have been constructed to control the linear wave energy converter and the composite energy storage system. The performance of the composite energy storage system has been verified in experiments by using electronics-based wave energy emulators.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Designing and Testing Composite Energy Storage Systems for Regulating the Outputs of Linear Wave Energy Converters

Nie

Xiao

Hiralal³

et al. 2017

Energies

View full text Add to dashboard Cite

show abstract

“…PMLGs for single-body point absorbers were discussed in [20,21] and for two-body floating point absorbers in [22]. Various topologies for PMLG for wave power conversion were summarized in [23], and some generator designs were compared in [23][24][25][26]. The type of magnets in the LG affects the performance and sustainability of the WEC.…”

Section: Introductionmentioning

confidence: 99%

Study of an Altered Magnetic Circuit of a Permanent Magnet Linear Generator for Wave Power

et al. 2017

View full text Add to dashboard Cite

The wave energy converter (WEC) studied and developed at Uppsala University in Sweden is a point absorbing buoy connected to a linear generator (LG) on the seabed. Previous studies have improved the sustainability of the generator, changing its magnets from Nd 2 Fe 14 B-magnets to ferrites. In this paper, the magnetic circuit of the linear generator is further studied. Ferrite magnets of two different types (Y30 and Y40) are studied along with different shapes of pole shoes for the system. The finite element method (FEM) simulations in a program called Ace are performed. The results show that a linear generator including both Y30 and Y40 magnets and shortened T-shaped pole shoes can generate a similar magnetic energy in the airgap as a linear generator only containing Y40 magnets and rectangular pole shoes. This shows that the magnetic circuit can be altered, opening up sizes and strengths of magnets for different retailers, and thereby possibly lowering magnet cost and transportation. This work was previously presented as a conference at the European Wave and Tidal Energy Conference (EWTEC) 2017 in Cork, Ireland; this manuscript has been carefully revised and some discussions, on magnet costs for example, have been added to this paper.

show abstract

“…However, for power rating of several hundred kilowatts the hydraulic system can be complex and expensive. Another option can be connecting a linear electrical generator directly with the oscillating buoy which reduces the system complexity [6]- [8]. However, power to weight ratio of linear generator is very poor compared to the rotary generator due to its low speed and partial utilization of its winding.…”

Section: Introductionmentioning

confidence: 99%

“…However, it requires a linear to rotary motion conversion mechanism. The rack and pinion gear arrangement for point absorber buoy is one such option to accomplish the required transformation of linear to rotary motion [6]. The paddle like WEC devices generally pump fluid which is taken to shore to run a turbine-generator set.…”

Section: Introductionmentioning

confidence: 99%

Operation of doubly fed induction generator in ocean wave energy conversion system by stator phase sequence switching

Hazra

Bhattacharya

2014

2014 IEEE Energy Conversion Congress and Exposition (ECCE)

View full text Add to dashboard Cite

This paper presents operation of a Doubly Fed Induction Generator (DFIG) to extract oscillatory power from ocean wave energy converter (WEC). DFIG has the advantage of generating power at both sub-synchronous and supersynchronous speed with only slip power to be handled by power converter at rotor side. At super-synchronous speed the rotor generates slip power along with the stator to take the net power generation above the generator power rating. Due to power generation capability above its rating, DFIG is a good candidate for WEC system. However, to operate DFIG in an oscillatory system where direction of rotor speed keeps changing it requires controlled supply from stator side as well. In this paper, a rotor side control method is proposed to operate the DFIG in oscillatory system with a low cost stator phase sequence switching circuit to adapt to the change of direction of the rotor speed. A suitable control scheme is proposed to control the machine flux during start up and speed reversal to eliminate current inrush at the stator side. The DFIG current is controlled in vector control method with control axes orientated along stator flux axis. The current controllers are designed to control the rotor side currents to produce power and to regulate machine flux in accordance with the wave energy converter dynamics. The system is modeled and simulated in MATLAB-Simulink platform to validate the proposed scheme. All the corresponding results are presented and discussed.

show abstract

Comparison of Direct-Drive Power Takeoff Systems for Ocean Wave Energy Applications

Cited by 59 publications

References 8 publications

Designing and Testing Composite Energy Storage Systems for Regulating the Outputs of Linear Wave Energy Converters

Designing and Testing Composite Energy Storage Systems for Regulating the Outputs of Linear Wave Energy Converters

Study of an Altered Magnetic Circuit of a Permanent Magnet Linear Generator for Wave Power

Operation of doubly fed induction generator in ocean wave energy conversion system by stator phase sequence switching

Contact Info

Product

Resources

About