Analysis of power extraction from irregular waves by all-electric power take off

Tedeschi, Elisabetta; Molinas, Marta; Carraro, Matteo; Mattavelli, Paolo

doi:10.1109/ecce.2010.5617893

Cited by 24 publications

(12 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The WEC system is reactively controlled. It is important to keep in mind the fact that losses do not behave bidirectionally [20] and that the accumulated average of the losses can become even larger than the average extracted mechanical power. The performed simulation is an example of this; the average extracted mechanical power is 2.57 kW, while the average losses are 2.72 kW.…”

Section: Simulation Results For a Reactive Controlled Systemmentioning

confidence: 99%

See 1 more Smart Citation

Exploring the Potential for Increased Production from the Wave Energy Converter Lifesaver by Reactive Control

et al. 2013

Self Cite

View full text Add to dashboard Cite

Fred Olsen is currently testing their latest wave energy converter (WEC), Lifesaver, outside of Falmouth Bay in England, preparing it for commercial operation at the Wavehub test site. Previous studies, mostly focusing on hydrodynamics and peak to average power reduction, have shown that this device has potential for increased power extraction using reactive control. This article extends those analyses, adding a detailed model of the all-electric power take-off (PTO) system, consisting of a permanent magnet synchronous generator, inverter and DC-link. Time domain simulations are performed to evaluate the PTO capabilities of the modeled WEC. However, when tuned towards reactive control, the generator losses become large, giving a very low overall system efficiency. Optimal control with respect to electrical output power is found to occur with low added mass, and when compared to pure passive loading, a 1% increase in annual energy production is estimated. The main factor reducing the effect of reactive control is found to be the minimum load-force constraint of the device. These results suggest that the Lifesaver has limited potential for increased production by reactive control. This analysis is nevertheless valuable, as it demonstrates how a wave-to-wire model can be used for investigation of PTO potential, annual energy production estimations and evaluations of different control techniques for a given WEC device.

show abstract

Section: Simulation Results For a Reactive Controlled Systemmentioning

confidence: 99%

“…To obtain unity closed-loop gain, K p >> L s ω, as shown in Equation (20). As the value for L s = 1.4 mH and ω e,max < n max 2π 60 n pp ≈ 5, 000, it is considered that K p = 25 is sufficiently large for all operation areas.…”

Section: Ls Rsmentioning

confidence: 99%

Exploring the Potential for Increased Production from the Wave Energy Converter Lifesaver by Reactive Control

et al. 2013

Self Cite

View full text Add to dashboard Cite

show abstract

“…The peak power limit is still assumed to be P lim = 500 kW and the point absorber velocity remains the reference value for control tuning. In this case the control technique behaves as an equivalent saturation [7][8] (thick trapezoidal waveform in the zoom of Fig. 3) and the corresponding control algorithm is very straightforward:…”

Section: B Equivalent Saturation Controlmentioning

confidence: 99%

Grid Connection Improvements by Control Strategy Selection for Wave Energy Converters

Santos¹,

Tedeschi²,

Ricci

et al. 2024

RE&PQJ

View full text Add to dashboard Cite

In this paper a wave-to-wire approach to model the exploitation of ocean energy by point absorbers in heave is presented. Attention is focused on the impact that the control strategy of the Wave Energy Converter (WEC) has both on the power performance of the single device and on the grid power quality at the connection point, when point absorbers are arranged in wave farms. Two different control strategies are proposed and compared to theoretical ones such as the complex-conjugate method. Their effectiveness in improving the system overall power extraction while reducing each Power Take-Off's rating and easing the Wave Farm grid integration is proved by time domain simulations, developed both at singledevice level and at farm level.

show abstract

“…The first one is related to the limited PTO rating, which is a limit to the maximum power that the PTO can output. The power limit is enforced by a flux weakening control system that works in the following way; when operating close to the power limit, the torque applied to the point absorber is decreased proportionally to the point absorber velocity so that the instantaneous power limit is never exceeded (Tedeschi et al, 2010). Moreover, under this operating condition, the applied torque is kept constant only when the extracted power is lower than the power limit.…”

Section: Power Capture With Constrained Ptomentioning

confidence: 99%

Impact of technical power take-off constraints on the power extraction of unidirectional and bidirectional point absorbers

Bozzetto

Spro

Tedeschi

2015

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering

Self Cite

View full text Add to dashboard Cite

Purpose – The purpose of this paper is to quantify the impact of the constraints of the power take-off system (PTO) on the power extraction of a point absorber wave energy converter (WEC). Such constraints include power, torque and maximum stroke limitations. Two different concepts, unidirectional and bidirectional point absorbers, are analysed, which both are relevant for practical applications in the wave energy industry. Design/methodology/approach – The two different cases of unidirectional and bidirectional point absorbers are analysed and directly compared. Moreover, a simplified control strategy is considered for the point absorber, which is based on a constant torque reference. The WEC performance is first evaluated in selected sea states and then the analysis is extended to assess the impact of the different solutions on the expected yearly wave energy production of the point absorber, when deployed at a specific location. The European Marine Energy Center (EMEC) is selected as the target site for the analysis. Findings – The analysis was performed in selected sea states and then it was extended to all the sea conditions occurring at the EMEC test site. The comparison between unidirectional and bidirectional operated devices suggested a clear superiority of the latter, ensuring similar power extraction at the expense of a halved required torque by the PTO. Moreover, a selective control strategy was implemented, and the results showed an increase in yearly energy production for the bidirectional device. Research limitations/implications – The study proved the importance of including the actual PTO constraints in the preliminary power assessment in order to avoid unrealistic overestimation of the expected power performance. Originality/value – The paper quantifies the power performance obtained with the application of such control strategy considering both unidirectional and bidirectional point absorbers. This analysis and comparison is extremely relevant since both unidirectional and bidirectional devices are reaching the market.

show abstract

Analysis of power extraction from irregular waves by all-electric power take off

Cited by 24 publications

References 12 publications

Exploring the Potential for Increased Production from the Wave Energy Converter Lifesaver by Reactive Control

Exploring the Potential for Increased Production from the Wave Energy Converter Lifesaver by Reactive Control

Grid Connection Improvements by Control Strategy Selection for Wave Energy Converters

Impact of technical power take-off constraints on the power extraction of unidirectional and bidirectional point absorbers

Contact Info

Product

Resources

About