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This paper investigates a passive control method of a point absorbing wave energy converter by considering the displacement and velocity constraints under irregular waves in the time domain. A linear generator is used as a power take-off unit, and the equivalent damping force is optimized to improve the power production of the wave energy converter. The results from nonlinear and linear passive control methods are compared, and indicate that the nonlinear passive control method leads to the excitation force in phase with the velocity of the converter that can significantly improve the energy production of the converter.

Ocean waves have huge amounts of energy, even larger than wind or solar, which can be extracted by some mechanical device. This can be done by creating a system of reacting forces, in which two or more bodies move relative to each other, while at least one body interacts with the waves. This moves the floater up and down. The floaters are connected to an arm structure, which are mounted on a fixed hull structure. Hence, the structure of the floater is very important. A static structural analysis with FSI (Fluid-Structure Interaction) analysis is conducted. To achieve the pressure load for the FSI analysis, the floater is simulated on a wave generator using rigid body motion. The structural analysis is done to examine the stresses on the whole system, and four types of flange and floater are optimized. The result shows that the structure of floater with wood support is the safest.

In Brasil, Sao Marcos Bay has a highly promising potential for the generation of electricity through the conversion of tidal current energy. This paper presents a methodology to study impacts of Hydrokinetic Energy Converter Farms (HECF) in coastal regions. Their location, power production and hydrodynamic, sedimentological and morphological processes are considered. For this purpose, idealized hydrosedimentological scenarios were modeled using the Base System for Environmental Hydrodynamics (SisBaHiA®) developed at COPPE/UFRJ. Three zones were identified for exploration. When an analytical power model was applied to these zones it yielded an annual potential output in the range of 134 GWh. Results of the hydrosedimentological model show alterations in sediment movement, as well as positive and negative interferences in power production. Interactions between HECF must be well understood to maximize power production and minimize adverse environmental impacts

In this paper the mathematical model of the rectifier AC voltage, built on the basis of thermoelectric energy converter. The model is divided into three main parts, including the calculation of inflow and outflow of heat to the junctions of the thermoelectric structure and calculation characteristics directly thermoelectric converter. Obtained plots, reflecting the basic properties of the thermoelectric rectifier AC voltage.

The paper presents a new array of oscillating wave energy converter, which is in accordance with nowadays’ research tendency of China: high power, high efficiency, high reliability and low cost. The paper gives the design scheme and design parameters of the new wave energy converter. It's composed of the wave energy converter unit, which can be assembled to arrays based on demand. Besides, the paper analyzes the power generation principle and advantages of the device. The research results could be a reference for wave energy’s exploration and utilization.

The aim of this paper to present the modeling of electronic energy converter in the popular development system LabVIEW. Using the various extensions and hardware capabilities it allows an intuitive, easy and comfortable way to examine, study and prototype these kind of devices. For example is reviewed an induction heating energy converter — parallel current source thyristor inverter. In the formalization and analysis of the power circuit are used interconnected parameters with which are described the behavior and operating regimes. The model is verified using the specialized simulation software LT Spice® and data taken from real electrothermic plants for induction heating.

In order to produce a large amount of electricity at a competitive cost, farms of Wave Energy Converters (WECs) will need to be deployed in the ocean. Due to hydrodynamic interaction between the devices, the geometric layout of the farm will influence the power production and affect the surrounding area around the WECs. Therefore it is essential to model both the near field effects and far field effects of the WEC farm. It is difficult, however, to model both, employing a single numerical model that offers the desired precision at a reasonable computational cost. The objective of this paper is to present a coupling methodology that will allow for the accurate modelling of both phenomena at a reasonably low computational cost. The one-way coupling proposed is between the Boundary Element Method (BEM) solver NEMOH, and the depth-averaged mild-slope wave propagation model, MILDwave. In the presented cases, NEMOH is used to resolve the near field effects whilst MILDwave is used to determine the far field effects.

The results of four phase switched reluctance motor tests were presented in this paper. Torque versus speed characteristics were executed for different control parameters. The energy converter designed to this motor allows to control phase current and switching angles independently. The experimental results show that the shape of the mechanical characteristics heavily depends of the switching angles and maximum phase current. It has been found through tests, that efficiency characteristics of the drive can be improved by the right adjustment of the switching angles, even in the low load conditions.

For generating performance analysis and experimental verification of a double-sided permanent magnet linear synchronous generator (PMLSG) with a slotless stator as shown in Fig. 1(a), this paper utilized a three-dimensional (3D) analysis method and manufactured model.

The power take-off (PTO) of a wave energy converter is defined as the mechanism with which the absorbed energy by the primary converter is transformed into useable electricity.

This paper uses experimental data to validate a wave energy converter (WEC) array hydrodynamics tool developed within the context of linearized potential flow theory. To this end, wave forces and power absorption by an array of five-point absorber WECs in monochromatic and panchromatic waves were measured from a set of deep-water wave basin experimental tests. Unlike the few other examples of WEC array experimental campaigns, the power take-off (PTO) system of each WEC was simulated by means of advanced equipment capable of accurately reproducing linear control strategies and, thereby, reducing the uncertainty in the physical model. Experimental measurements are then compared with numerical predictions showing reasonable agreement; the measured trends are, in the same way, well captured by the numerical predictions. Further analysis demonstrates that the developed tool can predict, on the safe side, wave forces and power absorption with less than 17.5% and 23.0% error, respectively, for more than 68% of the predictions.

In this paper, preliminarily a proposal for design guidelines for a “good” design of wave energy converter is presented and successively a small scale prototype of a wave energy converter including the buoyant electrical generator, the power electronics equipment and a sea water electrolyzer is designed on the basis of these guidelines and presented.

Purpose – The purpose of this paper is to describe the design and function of Fred. Olsen's wave energy converter (WEC) system Lifesaver with special focus on the stand-alone electrical system that is implemented for operation without grid-connection. Design/methodology/approach – The paper focus on the detailed design of the DC-Link system that drives the industrial 400 VAC inverters and generators for the production system. The DC-Link is stabilized by an ultra capacitor bank and has no external source or grid-connection. Findings – The system has been tested through extensive sea trials since April 2012 and has proved its function. Some results from real sea testing are presented. Practical implications – This paper proves the viability of the specified design and may serve as a basis for the design if similar systems in the future. Originality/value – This paper presents a WEC system that has proven successful operation through practical tests, and is therefore regarded as a high-value paper as there is limited experience on this subject.

Theoretical results are presented, mathematical model formation by means of inheritance from a generalized class template is shown for a general electromechanical energy converter., Приведены результаты теоретических исследований, показано формирование математической модели произвольного электромеханического преобразователя энергии путем наследования от обобщенного классового шаблона., Приведені результати теоретичних досліджень, показано формування математичної моделі довільного електромеханічного перетворювача енергії шляхом наслідування від узагальненого класового шаблону.

Ocean current near Miyake Island was measured by an Acoustic Doppler Current Profiler equipped on a moored buoy system from March 2013 to March 2014 for an ocean current energy converter development project. Current variations associated with the Kuroshio,tide and wind,were found in the observed record and are described in the paper. Based on the Kuroshio axis location, periods with and without the Kuroshio intrusion into the island were identified. Spectral analysis of the current speed revealed that the diurnal variation is enhanced when the Kuroshio does not intrude. This enhancement of diurnal current variation is possibly related to the generation of the Island-Trapped Waves. By combining the fine-scale observation data and the long-term coarse-resolution Kuroshio axis data, inter-annual variability of the current power was estimated. The estimated current power is about three times larger than the one estimated from an ocean reanalysis. The result implies that coarse-resolution non-tidal numerical models possibly underestimate current power in coastal ocean.

Understanding the hydrodynamics of waves and the wave energy resource is fundamental to the good design of wave energy converters. The wave energy resource can be defined by its temporal, directional and spectral characteristics, although many representations of the wave energy resource result in the removal of this information, with a consequential distortion of the apparent resource. This chapter discusses how wave energy resource data may be generated using numerical model and validated using site measurements. The chapter also discusses the processes that afffect wave propagation and lead to wave transformation. In its totality, the chapter provides sufficient details of the wave resource to allow an assessment of any particular wave resource assessment to be made, together wtith its potential impact on the performance of a wave energy converter.

This article is about one of the alternative forms of energy — the algorithm for the development of a sea wave energy converter, which is based on reflection, refraction, diffraction and interference analysis between waves and their energy transformers. This article provides information to the placement of a wave energy converter receiver, specially calculated parallel to the surface, thereby allowing obtaining wave energy step by step. It provides an insight into wave power plant optimization principles.

Energy harvesting in uniflow fluid environment aims at ambient energy that can be used in water environment for monitor equipment. In this paper, we focus on coupling both bending vibration and torsional vibration to gain better power generation. A novel structure of energy converter(arc-shaped) was designed and manufactured. Meanwhile the influence of vibrator with and without a pelvic fin was tested. Mathematical analyse due to vibration phenomenon and experimental result are reported. The 270-degree arc-shaped ring size piezoelectric ceramic is verified capable of producing an effective voltage over 10 V with the power of 0.5 mW.

The analyses of exergy and exergoeconomic calculations have been carried out at the Sarulla Geothermal Power Plant (SGPP) unit 1 which has a capacity of 110 MW. The evaluation and modelling process uses Engineering Equation Solver (EES) software commercial version v9.430. This research was conducted to identify exergy lost in certain components to provide suggestions for further development. Both energy efficiency and exergy are calculated based on the thermal fluid flow process on the SGPP. The calculations showed that energy efficiency for Ormat Energy Converter (OEC) Brine, OEC Bottoming, and overall SGPP are obtained in the amount of 13.4%, 7.67% and 10.57%, respectively. Meanwhile, efficiency exergy of OEC Brine, OEC Bottoming, and overall SGPP were obtained respectively at 38.94%, 33.51% and 39.97% with each exergy destruction flow rate at 32,935 kW, 34,726 kW, and 1,644,686 kW, respectively. The highest exergy destruction was obtained at reinjection wells of 58,263 kW, around 21.25% of the production wells exergy. Exergoeconomic analysis was also carried out through consideration of capital costs. The ratio of exergy and energy lost to capital costs is 6.14 Watt/US $ and 0.29 Watt/US $

In the recent years, the potential impact of wave energy converter (WEC) arrays on the surrounding wave field has been studied using both phase-averaging and phase-resolving wave propagation models. Obtaining understanding of this impact is important because it may affect other users in the sea or on the coastline. However, in these models a parametrization of the WEC power absorption is often adopted. This may lead to an overestimation or underestimation of the overall WEC array power absorption, and thus to an unrealistic estimation of the potential WEC array impact. WEC array power absorption is a result of energy extraction from the incoming waves, and thus wave height decrease is generally observed downwave at large distances (the so-called &ldquo, wake&rdquo, or &ldquo, far-field&rdquo, effects). Moreover, the power absorption depends on the mutual interactions between the WECs of an array (the so-called &ldquo, near field&rdquo, effects). To deal with the limitations posed by wave propagation models, coupled models of recent years, which are nesting wave-structure interaction solvers into wave propagation models, have been used. Wave-structure interaction solvers can generally provide detailed hydrodynamic information around the WECs and a more realistic representation of wave power absorption. Coupled models have shown a lower WEC array impact in terms of wake effects compared to wave propagation models. However, all studies to date in which coupled models are employed have been performed using idealized long-crested waves. Ocean waves propagate with a certain directional spreading that affects the redistribution of wave energy in the lee of WEC arrays, and thus gaining insight wake effect for irregular short-crested sea states is crucial. In our research, a new methodology is introduced for the assessment of WEC array wake effects for realistic sea states. A coupled model is developed between the wave-structure interaction solver NEMOH and the wave propagation model MILDwave. A parametric study is performed showing a comparison between WEC array wake effects for regular, long-crested irregular, and short-crested irregular waves. For this investigation, a nine heaving-point absorber array is used for which the wave height reduction is found to be up to 8% lower at 1.0 km downwave the WEC array when changing from long-crested to short-crested irregular waves. Also, an oscillating wave surge WEC array is simulated and the overestimation of the wake effects in this case is up to 5%. These differences in wake effects between different wave types indicates the need to consider short-crested irregular waves to avoid overestimating the WEC array potential impacts. The MILDwave-NEMOH coupled model has proven to be a reliable numerical tool, with an efficient computational effort for simulating the wake effects of two different WEC arrays under the action of a range of different sea states.

The purpose of this study was to improve the design construction of a float type wave micro energy converter. Especially we emphasized on the modelling of a metal capsule float type converter in order for better performance of its kind. At the same time we discussed some parameters on the basis of experimental study. Data concerning on the status of wave energetics and the process of development were discussed. The operating principle, advantages of the wave plant and its benefits as compared to the existing technology were reported. The project of a test installation of wave simulator and the research results were presented. The authors also investigated the electro technical characteristics of the generating unit. The developed micro unit of WMPP showed the possibility of energy generation at wave amplitude from 20cm and more when the wave oscillation period T within 1-5sec. The field research with the wave oscillation simulator confirmed the generation values of one micro unit within the capacity limits from 20 to 60W. It will broaden the possible opportunities and increase the WMPP capacity by a certain level if the micro units are constructed in cluster systems. © 2019 Published under licence by IOP Publishing Ltd.

This paper introduces the analysis and design of a wave energy converter (WEC) that is equipped with a novel kind of electrostatic power take-off system, known as dielectric elastomer generator (DEG). We propose a modelling approach which relies on the combination of nonlinear potential-flow hydrodynamics and electro-hyperelastic theory. Such a model makes it possible to predict the system response in operational conditions, and thus it is employed to design and evaluate a DEG-based WEC that features an effective dynamic response. The model is validated through the design and test of a small-scale prototype, whose dynamics is tuned with waves at tank-scale using a set of scaling rules for the DEG dimensions introduced here in order to comply with Froude similarity laws. Wave-tank tests are conducted in regular and irregular waves with a functional DEG system that is controlled using a realistic prediction-free strategy. Remarkable average performance in realistically scaled sea states has been recorded during experiments, with peaks of power output of up to 3.8 W, corresponding to hundreds of kilowatts at full-scale. The obtained results demonstrated the concrete possibility of designing DEG-based WEC devices that are conceived for large-scale electrical energy production.

To construct beta converters with maximum efficiency it is necessary to carry out the theoretical calculation in order to determine their optimal parameters - the geometry of the structure, the thickness of the deposition of the radioisotope layer, the depth and the width of the p-n junction, and others. To date, many different theoretical models and calculations methods had been proposed. There are fairly simple theoretical models based on the Bethe-Bloch formula and the calculation of the rate of generation of electron-hole pairs, and on calculations by equivalent circuits. Also, the Monte-Carlo method is used for theoretical modeling of beta converters. This paper explores beta converter optimization using the Monte-Carlo method. The purpose of the study is to conduct Monte-Carlo simulation of the beta converter to determine its optimal parameters.

The wave absorbing control using wave sensors was theorized and developed by the authors, about 30 years ago. It was originally for absorbing wavemakers for tank tests in laboratories. This control enables wavemakers to generate the desired incident waves while absorbing undesirable reflected waves from the tank wall. When waves are absorbed by the wavemaker, the energy of the waves are also absorbed, that is, the energy is regenerated to electric power with the wavemaker drivemotor. According to this theory, in case that certain waves are generated by an oscillating body, these waves can be absorbed by the same body. Therefore, we can design a wave energy converter as a kind of absorbing wavemaker.

The free piston energy converter (FPEC) is a combination of a combustion engine and a linear electrical machine which develops a new type of power unit for hybrid electric vehicle. The movement component of the FPEC is a multi-input multi-output coupling nonlinear system. As a consequence, an adaptive decoupling control strategy is presented in this paper for controlling the piston motion. Two neural PID controllers in parallel are employed as the decoupling controller, in which PID gains are auto adjusted by supervised Hebbs learning rule. Simulation results show that the utilization of the neural adaptive PID decoupling controller gives rise to stabilize the piston motion.

This article proposes a simple and reliable damping strategy for wave powerfarm operation of small-scale point-absorber converters. The strategy is based on passiverectification onto a constant DC-link, making it very suitable for grid integration of the farm.A complete model of the system has been developed in Matlab Simulink, and uses real sitedata as input. The optimal constant DC-voltage is evaluated as a function of the significantwave height and energy period of the waves. The total energy output of the WEC is derivedfor one year of experimental site data. The energy output is compared for two cases, onewhere the optimal DC-voltage is determined and held constant at half-hour basis throughoutthe year, and one where a selected value of the DC-voltage is kept constant throughout theyear regardless of sea state.