WorldWideScience

Sample records for in-stream energy converters

  1. Thermionic photovoltaic energy converter

    Science.gov (United States)

    Chubb, D. L. (Inventor)

    1985-01-01

    A thermionic photovoltaic energy conversion device comprises a thermionic diode mounted within a hollow tubular photovoltaic converter. The thermionic diode maintains a cesium discharge for producing excited atoms that emit line radiation in the wavelength region of 850 nm to 890 nm. The photovoltaic converter is a silicon or gallium arsenide photovoltaic cell having bandgap energies in this same wavelength region for optimum cell efficiency.

  2. SSG Wave Energy Converter

    DEFF Research Database (Denmark)

    Margheritini, Lucia; Vicinanza, Diego; Frigaard, Peter

    2008-01-01

    head hydroturbines are converting the potential energy of the stored water into power. A key to success for the SSG will be the low cost of the structure and its robustness. The construction of the pilot plant is scheduled and this paper aims to describe the concept of the SSG wave energy converter...... and the studies behind the process that leads to its construction. The pilot plant is an on-shore full scale module in 3 levels with an expected power production of 320 MWh/y in the North Sea. Location, wave climate and laboratory tests results will be used here to describe the pilot plant and its characteristics.......The SSG (Sea Slot-cone Generator) is a wave energy converter of the overtopping type. The structure consists of a number of reservoirs one on the top of each others above the mean water level, in which the water of incoming waves is stored temporary. In each reservoir, expressively designed low...

  3. Cycloidal Wave Energy Converter

    Energy Technology Data Exchange (ETDEWEB)

    Stefan G. Siegel, Ph.D.

    2012-11-30

    This program allowed further advancing the development of a novel type of wave energy converter, a Cycloidal Wave Energy Converter or CycWEC. A CycWEC consists of one or more hydrofoils rotating around a central shaft, and operates fully submerged beneath the water surface. It operates under feedback control sensing the incoming waves, and converts wave power to shaft power directly without any intermediate power take off system. Previous research consisting of numerical simulations and two dimensional small 1:300 scale wave flume experiments had indicated wave cancellation efficiencies beyond 95%. The present work was centered on construction and testing of a 1:10 scale model and conducting two testing campaigns in a three dimensional wave basin. These experiments allowed for the first time for direct measurement of electrical power generated as well as the interaction of the CycWEC in a three dimensional environment. The Atargis team successfully conducted two testing campaigns at the Texas A&M Offshore Technology Research Center and was able to demonstrate electricity generation. In addition, three dimensional wave diffraction results show the ability to achieve wave focusing, thus increasing the amount of wave power that can be extracted beyond what was expected from earlier two dimensional investigations. Numerical results showed wave cancellation efficiencies for irregular waves to be on par with results for regular waves over a wide range of wave lengths. Using the results from previous simulations and experiments a full scale prototype was designed and its performance in a North Atlantic wave climate of average 30kW/m of wave crest was estimated. A full scale WEC with a blade span of 150m will deliver a design power of 5MW at an estimated levelized cost of energy (LCOE) in the range of 10-17 US cents per kWh. Based on the new results achieved in the 1:10 scale experiments these estimates appear conservative and the likely performance at full scale will

  4. Gallium phosphide energy converters

    Energy Technology Data Exchange (ETDEWEB)

    Sims, P.E.; Dinetta, L.C.; Goetz, M.A.

    1995-10-01

    Gallium phosphide (GaP) energy converters may be successfully deployed to provide new mission capabilities for spacecraft. Betavoltaic power supplies based on the conversion of tritium beta decay to electricity using GaP energy converters can supply long term low-level power with high reliability. High temperature solar cells, also based on GaP, can be used in inward-bound missions greatly reducing the need for thermal dissipation. Results are presented for GaP direct conversion devices powered by Ni-63 and compared to the conversion of light emitted by tritiarated phosphors. Leakage currents as low as 1.2 x 10(exp {minus}17) A/sq cm have been measured and the temperature dependence of the reverse saturation current is found to have ideal behavior. Temperature dependent IV, QE, R(sub sh), and V(sub oc) results are also presented. These data are used to predict the high-temperature solar cell and betacell performance of GaP devices and suggest appropriate applications for the deployment of this technology.

  5. Electromagnetic wave energy converter

    Science.gov (United States)

    Bailey, R. L. (Inventor)

    1973-01-01

    Electromagnetic wave energy is converted into electric power with an array of mutually insulated electromagnetic wave absorber elements each responsive to an electric field component of the wave as it impinges thereon. Each element includes a portion tapered in the direction of wave propagation to provide a relatively wideband response spectrum. Each element includes an output for deriving a voltage replica of the electric field variations intercepted by it. Adjacent elements are positioned relative to each other so that an electric field subsists between adjacent elements in response to the impinging wave. The electric field results in a voltage difference between adjacent elements that is fed to a rectifier to derive dc output power.

  6. A thermochemical energy converter

    Energy Technology Data Exchange (ETDEWEB)

    Toyeguti, K.; Indzima, T.

    1982-08-09

    Mercury is used as the active mass of the anode in the converter and 0/sub 2/ is used as the active cathode material. The reaction of Mercury + 1/2 0/sub 2/-Hg0 occurs with a discharge. With heating to 500/sup 0/C the regeneration of the Mercury, Hg0 yields Mercury + 1/2 0/sub 2/, occurs. The device for performing the thermochenical conversion of energy contains an element body, an oxygen chamber, an oxygen electrode, a chamber with an alkaline liquid electrolyte, a separator, an auxiliary separator, an electrode and a chamber with the Mercury. The thermochemical reaction occurs in the reactor to which the Hg0 is transported along a pipe which has a refrigerator and a valve. The Mercury is fed into the element from a reservoir. The Mercury reduced in the reactor and in a reaction tower is fed into it through a closed cycle. The bellows is connected with the reactor by a pipe with a refrigerator. Through it the 0/sub 2/ goes in a closed cycle to the chamber. The current forming reactions are Hg + 20H-anion yields Hg0 + H/sub 2/0 + 2e and 1/2 0/sub 2/ + H/sub 2/0 + 2e yields 20H-anion. The voltage on the outleads of the element is approximately 0.3 volts.

  7. Proposed electromagnetic wave energy converter

    Science.gov (United States)

    Bailey, R. L.

    1973-01-01

    Device converts wave energy into electric power through array of insulated absorber elements responsive to field of impinging electromagnetic radiation. Device could also serve as solar energy converter that is potentially less expensive and fragile than solar cells, yet substantially more efficient.

  8. Wave energy converter test application

    OpenAIRE

    Hottola, Niko

    2016-01-01

    This thesis was made for wave energy company Wello Oy. Given assignment was to find the suitable generator and frequency converter for a wave energy converter test application. The primary objective was to find a suitable generator for direct drive, in order to avoid the weight of the test application rising too high. In this thesis the possible machine types for test application are presented and what are their advenatages and disadvantages. In addition, the operation of the frequency co...

  9. Reliability of Wave Energy Converters

    DEFF Research Database (Denmark)

    Ambühl, Simon

    . Structural reliability considerations and optimizations impact operation and maintenance (O&M) costs as well as the initial investment costs. Furthermore, there is a control system for WEC applications which defines the harvested energy but also the loads onto the structure. Therefore, extreme loads but also...... WEPTOS. Calibration of safety factors are performed for welded structures at theWavestar device including different control systems for harvesting energy from waves. In addition, a case study of different O&M strategies for WECs is discussed, and an example of reliability-based structural optimization......There are many different working principles for wave energy converters (WECs) which are used to produce electricity from waves. In order for WECs to become successful and more competitive to other renewable electricity sources, the consideration of the structural reliability of WECs is essential...

  10. Reliability of Wave Energy Converters

    DEFF Research Database (Denmark)

    Ambühl, Simon

    for welded structures at the Wavestar device includingdifferent control systems for harvesting energy from waves. In addition, a casestudy of different O&M strategies for WECs is discussed, and an example ofreliability-based structural optimization of the Wavestar foundation ispresented. The work performed......There are many different working principles for wave energy converters (WECs) which are used to produce electricity from waves. In order for WECs tobecome successful and more competitive to other renewable electricity sources,the consideration of the structural reliability of WECs is essential.......Structural reliability considerations and optimizations impact operation andmaintenance (O&M) costs as well as the initial investment costs.Furthermore, there is a control system for WEC applications which defines theharvested energy but also the loads onto the structure. Therefore, extremeloads but also fatigue loads...

  11. The SSG Wave Energy Converter

    DEFF Research Database (Denmark)

    Vicinanza, Diego; Margheritini, Lucia; Kofoed, Jens Peter

    2012-01-01

    The Sea-wave Slot-cone Generator concept (SSG) is a Wave Energy Converter based on the wave overtopping principle utilizing several reservoirs placed on top of each other, in which the energy of the incoming wave will be stored as potential energy. The water captured in the reservoirs will then run...... through turbines for electricity production. The system utilizes a wide spectrum of different wave conditions by means of multiple reservoirs, located at different levels above the still water level. Thereby, it obtains a high overall efficiency and it can be suitable for shoreline and breakwater...... applications, presenting particular advantages such as: sharing structure costs, availability of grid connection and infrastructures, recirculation of water inside the harbor, as the outlet of the turbines is on the rear part of the system. Recently, plans for the SSG pilot installation were in progress...

  12. Reliability of Wave Energy Converters

    DEFF Research Database (Denmark)

    Ambühl, Simon

    There are many different working principles for wave energy converters (WECs) which are used to produce electricity from waves. In order for WECs to become successful and more competitive to other renewable electricity sources, the consideration of the structural reliability of WECs is essential....... Structural reliability considerations and optimizations impact operation and maintenance (O&M) costs as well as the initial investment costs. Furthermore, there is a control system for WEC applications which defines the harvested energy but also the loads onto the structure. Therefore, extreme loads but also...... of the Wavestar foundation is presented. The work performed in this thesis focuses on the Wavestar and WEPTOS WEC devices which are only two working principles out of a large diversity. Therefore, in order to gain general statements and give advice for standards for structural WEC designs, more working principles...

  13. Radiant energy to electric energy converter

    Science.gov (United States)

    Sher, Arden (Inventor)

    1980-01-01

    Radiant energy is converted into electric energy by irradiating a capacitor including an ionic dielectric. The dielectric is a sintered crystal superionic conductor, e.g., lanthanum trifluoride, lanthanum trichloride, or silver bromide, so that a multiplicity of crystallites exist between electrodes of the capacitor. The radiant energy cyclically irradiates the dielectric so that the dielectric exhibits a cyclic photocapacitive like effect. Adjacent crystallites have abutting surfaces that enable the crystallites to effectively form a multiplicity of series capacitor elements between the electrodes. Each of the capacitor elements has a dipole layer only on or near its surface. The capacitor is initially charged to a voltage just below the dielectric breakdown voltage by connecting it across a DC source causing a current to flow through a charging resistor to the dielectric. The device can be utilized as a radiant energy detector or as a solar energy cell.

  14. Ocean floor mounting of wave energy converters

    Science.gov (United States)

    Siegel, Stefan G

    2015-01-20

    A system for mounting a set of wave energy converters in the ocean includes a pole attached to a floor of an ocean and a slider mounted on the pole in a manner that permits the slider to move vertically along the pole and rotate about the pole. The wave energy converters can then be mounted on the slider to allow adjustment of the depth and orientation of the wave energy converters.

  15. State estimation for wave energy converters

    Energy Technology Data Exchange (ETDEWEB)

    Bacelli, Giorgio; Coe, Ryan Geoffrey

    2017-04-01

    This report gives a brief discussion and examples on the topic of state estimation for wave energy converters (WECs). These methods are intended for use to enable real-time closed loop control of WECs.

  16. Underwater noise from a wave energy converter

    DEFF Research Database (Denmark)

    Tougaard, Jakob

    A recent addition to the anthropogenic sources of underwater noise is offshore wave energy converters. Underwater noise was recorded from the Wavestar wave energy converter located at Hastholm, Denmark (57°7.73´N, 8°37.23´E). The Wavestar is a full-scale test and demonstration converter...... in full operation and start and stop of the converter. Median broad band (10 Hz – 20 kHz) sound pressure level (Leq) was 123 dB re. 1 Pa, irrespective of status of the wave energy converter (stopped, running or starting/stopping). The most pronounced peak in the third-octave spectrum was in the 160 Hz...... significant noise above ambient could be detected above the 250 Hz band. The absolute increase in noise above ambient was very small. L50 third-octave levels in the four bands with the converter running were thus only 1-2 dB above ambient L50 levels. The noise recorded 25 m from the wave energy converter...

  17. Solar energy converter using surface plasma waves

    Science.gov (United States)

    Anderson, L. M. (Inventor)

    1984-01-01

    Sunlight is dispersed over a diffraction grating formed on the surface of a conducting film on a substrate. The angular dispersion controls the effective grating period so that a matching spectrum of surface plasmons is excited for parallel processing on the conducting film. The resulting surface plasmons carry energy to an array of inelastic tunnel diodes. This solar energy converter does not require different materials for each frequency band, and sunlight is directly converted to electricity in an efficient manner by extracting more energy from the more energetic photons.

  18. Aquabuoy Wave Energy Converter

    DEFF Research Database (Denmark)

    Vicinanza, Diego; Margheritini, Lucia; Frigaard, Peter

    The work reported here is part of the contract agreement between the Finavera Renewables Ocean Energy Ltd. and the Department of Civil Engineering Hydraulics and Coastal Engineering Laboratory to instrument a model in scale 1:10 to prototype of the AquaBuOY (AB) wave energy converter and to analyse...

  19. Near-Shore Floating Wave Energy Converters

    DEFF Research Database (Denmark)

    Ruol, Piero; Zanuttigh, Barbara; Martinelli, Luca

    2011-01-01

    Aim of this note is to analyse the possible application of a Wave Energy Converter (WEC) as a combined tool to protect the coast and harvest energy. Physical model tests are used to evaluate wave transmission past a near-shore floating WEC of the wave activated body type, named DEXA. Efficiency...

  20. Semiconductor electrolyte photovoltaic energy converter

    Science.gov (United States)

    Anderson, W. W.; Anderson, L. B.

    1975-01-01

    Feasibility and practicality of a solar cell consisting of a semiconductor surface in contact with an electrolyte are evaluated. Basic components and processes are detailed for photovoltaic energy conversion at the surface of an n-type semiconductor in contact with an electrolyte which is oxidizing to conduction band electrons. Characteristics of single crystal CdS, GaAs, CdSe, CdTe and thin film CdS in contact with aqueous and methanol based electrolytes are studied and open circuit voltages are measured from Mott-Schottky plots and open circuit photo voltages. Quantum efficiencies for short circuit photo currents of a CdS crystal and a 20 micrometer film are shown together with electrical and photovoltaic properties. Highest photon irradiances are observed with the GaAs cell.

  1. Development of the Wave Energy Converter

    DEFF Research Database (Denmark)

    Kofoed, Jens Peter; Frigaard, Peter; Sørensen, Hans Christian

    2000-01-01

    The development of the wave energy converter Wave Dragon (WD) is presented. The WD is based on the overtopping principle. Initially a description of the WD is given. Then the development over time in terms of the various research and development projects working with the concept is described...

  2. Performance Evaluation of Wave Energy Converters

    DEFF Research Database (Denmark)

    Pecher, Arthur

    Ocean waves provide a sustainable, power-dense, predictable and widely available source of energy that could provide about 10 % of worlds energy needs. While research into wave energy has been undertaken for decades, a significant increase in related activities has been seen in the recent years......, with more than 150 concepts currently being developed worldwide. Wave energy conversion concepts can be of many kinds, as the energy in the waves can be absorbed in many different ways. However, each concept is expected to require a thorough development process, involving different phases and prototypes....... Guidelines for the development of wave energy converters recommend the use of different prototypes, having different sizes, which have to perform tank tests or sea trials. This implicates the need of different testing environment, which shifts from being controllable to uncontrollable with the development...

  3. Coordinated Control of Wave Energy Converters Subject to Motion Constraints

    OpenAIRE

    2016-01-01

    In this paper, a generic coordinated control method for wave energy converters is proposed, and the constraints on motion amplitudes and the hydrodynamic interaction between converters are considered. The objective of the control problem is to maximize the energy converted from ocean waves, and this is achieved by coordinating the power take-off (PTO) damping of each wave energy converter in the frequency domain in each sea state. In a case study, a wave energy farm consisting of four convert...

  4. Performance Evaluation of Wave Energy Converters

    DEFF Research Database (Denmark)

    Pecher, Arthur

    Ocean waves provide a sustainable, power-dense, predictable and widely available source of energy that could provide about 10 % of worlds energy needs. While research into waveenergy has been undertaken for decades, a significant increase in related activities has been seen in the recent years......, with more than 150 concepts currently being developed worldwide. Wave energy conversion concepts can be of many kinds, as the energy in the waves can be absorbed in many different ways. However, each concept is expected to require a thorough development process, involving different phases and prototypes....... Guidelines for the development of wave energy converters recommend the use of different prototypes, having different sizes, which have to perform tank tests or sea trials. Thisimplicates the need of different testing environment, which shifts from being controllable to uncontrollable with the development...

  5. Levelized Cost of Energy of the Weptos wave energy converter

    DEFF Research Database (Denmark)

    Pecher, Arthur; Kofoed, Jens Peter

    This report presents the cost of energy calculations of a wave energy array of 90 MW, consisting of 25 x 3.6 MW Weptos wave energy converters. The calculation has been made in analogy with a publically available document presented by the UK government, covering the case of a similar size wind...

  6. Power Generation Using Mechanical Wave Energy Converter

    Directory of Open Access Journals (Sweden)

    Srinivasan Chandrasekaran

    2012-03-01

    Full Text Available Ocean wave energy plays a significant role in meeting the growing demand of electric power. Economic, environmental, and technical advantages of wave energy set it apart from other renewable energy resources. Present study describes a newly proposed Mechanical Wave Energy Converter (MEWC that is employed to harness heave motion of floating buoy to generate power. Focus is on the conceptual development of the device, illustrating details of component level analysis. Employed methodology has many advantages such as i simple and easy fabrication; ii easy to control the operations during rough weather; and iii low failure rate during normal sea conditions. Experimental investigations carried out on the scaled model of MWEC show better performance and its capability to generate power at higher efficiency in regular wave fields. Design Failure Mode and Effect Analysis (FMEA shows rare failure rates for all components except the floating buoy.

  7. Clustering of cycloidal wave energy converters

    Science.gov (United States)

    Siegel, Stefan G.

    2016-03-29

    A wave energy conversion system uses a pair of wave energy converters (WECs) on respective active mountings on a floating platform, so that the separation of the WECs from each other or from a central WEC can be actively adjusted according to the wavelength of incident waves. The adjustable separation facilitates operation of the system to cancel reactive forces, which may be generated during wave energy conversion. Modules on which such pairs of WECs are mounted can be assembled with one or more central WECs to form large clusters in which reactive forces and torques can be made to cancel. WECs of different sizes can be employed to facilitate cancelation of reactive forces and torques.

  8. Converting energy from fusion into useful forms

    CERN Document Server

    Kovari, M; Jenkins, I; Kiely, C

    2014-01-01

    If fusion power reactors are to be feasible, it will still be necessary to convert the energy of the nuclear reaction into usable form. The heat produced will be removed from the reactor core by a primary coolant, which might be water, helium, molten lithium-lead, molten lithium-containing salt, or CO2. The heat could then be transferred to a conventional Rankine cycle or Brayton (gas turbine) cycle. Alternatively it could be used for thermochemical processes such as producing hydrogen or other transport fuels. Fusion presents new problems because of the high energy neutrons released. These affect the selection of materials and the operating temperature, ultimately determining the choice of coolant and working cycle. The limited temperature ranges allowed by present day irradiated structural materials, combined with the large internal power demand of the plant, will limit the overall thermal efficiency. The operating conditions of the fusion power source, the materials, coolant, and energy conversion system w...

  9. Wind Energy Conversion Based on Matrix Converter

    Directory of Open Access Journals (Sweden)

    Mutharasan Anburaj

    2014-07-01

    Full Text Available In recent years renewable sources such as solar, wave and wind are used for the generation of electricity. Wind is one of the major renewable sources. The amount of energy from a Wind Energy Conversion System (WECS depends not only on the wind at the site, but also on the control strategy used for the WECS. In assistance to get the appropriate wind energy from the conversion system, wind turbine generator will be run in variable speed mode. The variable speed capability is achieved through the use of an advanced power electronic converter. Fixed speed wind turbines and induction generators are often used in wind farms. But the limitations of such generators are low efficiency and poor power quality which necessitates the variable speed wind turbine generators such as Doubly Fed Induction Generator (DFIG and Permanent Magnet Synchronous Generator (PMSG. A high-performance configuration can be obtained by using Scherbius drive composed of a DFIG and a converter in combination AC-DC-AC connect between stator & rotor points for providing the required variable speed operation

  10. Mechanical vibration to electrical energy converter

    Science.gov (United States)

    Kellogg, Rick Allen; Brotz, Jay Kristoffer

    2009-03-03

    Electromechanical devices that generate an electrical signal in response to an external source of mechanical vibrations can operate as a sensor of vibrations and as an energy harvester for converting mechanical vibration to electrical energy. The devices incorporate a magnet that is movable through a gap in a ferromagnetic circuit, wherein a coil is wound around a portion of the ferromagnetic circuit. A flexible coupling is used to attach the magnet to a frame for providing alignment of the magnet as it moves or oscillates through the gap in the ferromagnetic circuit. The motion of the magnet can be constrained to occur within a substantially linear range of magnetostatic force that develops due to the motion of the magnet. The devices can have ferromagnetic circuits with multiple arms, an array of magnets having alternating polarity and, encompass micro-electromechanical (MEM) devices.

  11. Parametric study of laser photovoltaic energy converters

    Science.gov (United States)

    Walker, G. H.; Heinbockel, J. H.

    1987-01-01

    Photovoltaic converters are of interest for converting laser power to electrical power in a space-based laser power system. This paper describes a model for photovoltaic laser converters and the application of this model to a neodymium laser silicon photovoltaic converter system. A parametric study which defines the sensitivity of the photovoltaic parameters is described. An optimized silicon photovoltaic converter has an efficiency greater than 50 percent for 1000 W/sq cm of neodymium laser radiation.

  12. Image processing to optimize wave energy converters

    Science.gov (United States)

    Bailey, Kyle Marc-Anthony

    The world is turning to renewable energies as a means of ensuring the planet's future and well-being. There have been a few attempts in the past to utilize wave power as a means of generating electricity through the use of Wave Energy Converters (WEC), but only recently are they becoming a focal point in the renewable energy field. Over the past few years there has been a global drive to advance the efficiency of WEC. Placing a mechanical device either onshore or offshore that captures the energy within ocean surface waves to drive a mechanical device is how wave power is produced. This paper seeks to provide a novel and innovative way to estimate ocean wave frequency through the use of image processing. This will be achieved by applying a complex modulated lapped orthogonal transform filter bank to satellite images of ocean waves. The complex modulated lapped orthogonal transform filterbank provides an equal subband decomposition of the Nyquist bounded discrete time Fourier Transform spectrum. The maximum energy of the 2D complex modulated lapped transform subband is used to determine the horizontal and vertical frequency, which subsequently can be used to determine the wave frequency in the direction of the WEC by a simple trigonometric scaling. The robustness of the proposed method is provided by the applications to simulated and real satellite images where the frequency is known.

  13. A New Modular Multilevel Converter with Integrated Energy Storage

    DEFF Research Database (Denmark)

    Trintis, Ionut; Munk-Nielsen, Stig; Teodorescu, Remus

    2011-01-01

    This paper introduces a new modular converter with integrated energy storage based on the cascaded half-bridge modular multilevel converter with common DC bus. It represents a complete modular solution with power electronics and energy storage building blocks, for medium and high voltage...... in the future HVDC meshed grids. Its functionality and flexibility makes the converter independent on the energy storage unit characteristic. The converter concept with its basic functions and control schemes are described and evaluated in this paper....

  14. Bidirectional converter interface for a battery energy storage test bench

    DEFF Research Database (Denmark)

    Trintis, Ionut; Thomas, Stephan; Blank, Tobias;

    2011-01-01

    This paper presents the bidirectional converter interface for a 6 kV battery energy storage test bench. The power electronic interface consists a two stage converter topology having a low voltage dc-ac grid connected converter and a new dual active bridge dc-dc converter with high transformation...... ratio. The dc-dc converter controls the battery charge/discharge current while the grid converter controls the common dc-link voltage and the grid current. The applied control structures and the hardware implementation of both converters are presented, together with their interaction. Experimental...

  15. Bidirectional converter interface for a battery energy storage test bench

    DEFF Research Database (Denmark)

    Trintis, Ionut; Thomas, Stephan; Blank, Tobias

    2011-01-01

    This paper presents the bidirectional converter interface for a 6 kV battery energy storage test bench. The power electronic interface consists a two stage converter topology having a low voltage dc-ac grid connected converter and a new dual active bridge dc-dc converter with high transformation...... ratio. The dc-dc converter controls the battery charge/discharge current while the grid converter controls the common dc-link voltage and the grid current. The applied control structures and the hardware implementation of both converters are presented, together with their interaction. Experimental...

  16. Operation and maintenance strategies for wave energy converters

    DEFF Research Database (Denmark)

    Ambühl, Simon; Marquis, Laurent; Kofoed, Jens Peter;

    2015-01-01

    Inspection and maintenance costs are a significant contributor to the cost of energy for wave energy converters. There are different operation and maintenance strategies for wave energy converters. Maintenance can be performed after failure (corrective) or before a breakdown (preventive) occurs...... and maintenance costs estimations for wave energy converter applications including real weather data and damage accumulation. Furthermore, uncertainties related with costs, structural damage accumulation, inspection accuracy and different maintenance strategies can be included. This article contains a case study...

  17. Research on Energy Conversion System of Floating Wave Energy Converter

    Institute of Scientific and Technical Information of China (English)

    张亚群; 盛松伟; 游亚戈; 吴必军; 刘洋

    2014-01-01

    A wave power device includes an energy harvesting system and a power take-off system. The power take-off system of a floating wave energy device is the key that converts wave energy into other forms. A set of hydraulic power take-off system, which suits for the floating wave energy devices, includes hydraulic system and power generation system. The hydraulic control system uses a special“self-hydraulic control system”to control hydraulic system to release or save energy under the maximum and the minimum pressures. The maximum pressure is enhanced to 23 MPa, the minimum to 9 MPa. Quite a few experiments show that the recent hydraulic system is evidently improved in efficiency and reliability than our previous one, that is expected to be great significant in the research and development of our prototype about wave energy conversion.

  18. Grid Converters for Stationary Battery Energy Storage Systems

    DEFF Research Database (Denmark)

    Trintis, Ionut

    to hours, rated at MW and MWh, battery energy storage systems are suitable and ecient solutions. Grid connection of the storage system can be done at dierent voltage levels, depending on the location and application scenario. For high power and energy ratings, increase in the battery and converter voltage...... was realized for a 100 kW active rectier to be used in a 6 kV battery energy storage test bench. In the second part, dierent solutions for power converters to interface energy storage units to medium voltage grid are given. A new modular multilevel converter concept is introduced, where the energy storage......-voltage 100 kW bidirectional grid converter, to be used in a high voltage battery energy storage test bench. The control structure proved to be stable without damping. The converter was tested in the test bench and the experimental results are presented. Multilevel converters are replacing the classical two...

  19. Symmetry Analysis of Thermoelectric Energy Converters with Inhomogeneous Legs

    Science.gov (United States)

    Korzhuev, M. A.

    2010-09-01

    Symmetry analysis has been applied to thermoelectric energy converters [thermoelectric generators (TEG), coolers (TEC), and heaters (TEH)] with inhomogeneous legs. The features of the crystallographic symmetry of thermoelectric materials and the symmetry of legs, thermocouples, and modules are studied. The effect of symmetry on the figure of merit Z of thermoelectric energy converters is considered. A general rule for proper placement of legs in thermoelectric converters is developed. A modified tetratomic classification for thermoelectric energy converters with inhomogeneous legs (TEGa, TEGb, TEC, and TEH) is proposed. An increase in Z for thermoelectric energy converters with inhomogeneous legs is due to the bulk thermoelectric effect. An increase in Z gives the reduction of irreversible processes in the modules (Joule heating and thermal conductivity), accompanying breaking of the symmetry of the legs. It is found that violations of the symmetry requirements can lead to significant energy losses in converters.

  20. Wave Dragon Wave Energy Converters Used as Coastal Protection

    DEFF Research Database (Denmark)

    Nørgaard, Jørgen Harck; Andersen, Thomas Lykke; Kofoed, Jens Peter

    2011-01-01

    This paper deals with wave energy converters used to reduce the wave height along shorelines. For this study the Wave Dragon wave energy converter is chosen. The wave height reduction from a single device has been evaluated from physical model tests in scale 1:51.8 of the 260 x 150 m, 24 kW/m model...

  1. Combination solar photovoltaic heat engine energy converter

    Science.gov (United States)

    Chubb, Donald L.

    1987-01-01

    A combination solar photovoltaic heat engine converter is proposed. Such a system is suitable for either terrestrial or space power applications. The combination system has a higher efficiency than either the photovoltaic array or the heat engine alone can attain. Advantages in concentrator and radiator area and receiver mass of the photovoltaic heat engine system over a heat-engine-only system are estimated. A mass and area comparison between the proposed space station organic Rankine power system and a combination PV-heat engine system is made. The critical problem for the proposed converter is the necessity for high temperature photovoltaic array operation. Estimates of the required photovoltaic temperature are presented.

  2. Strained quantum well photovoltaic energy converter

    Science.gov (United States)

    Freundlich, Alexandre (Inventor); Renaud, Philippe (Inventor); Vilela, Mauro Francisco (Inventor); Bensaoula, Abdelhak (Inventor)

    1998-01-01

    An indium phosphide photovoltaic cell is provided where one or more quantum wells are introduced between the conventional p-conductivity and n-conductivity indium phosphide layer. The approach allows the cell to convert the light over a wider range of wavelengths than a conventional single junction cell and in particular convert efficiently transparency losses of the indium phosphide conventional cell. The approach hence may be used to increase the cell current output. A method of fabrication of photovoltaic devices is provided where ternary InAsP and InGaAs alloys are used as well material in the quantum well region and results in an increase of the cell current output.

  3. Coordinated Control of Wave Energy Converters Subject to Motion Constraints

    Directory of Open Access Journals (Sweden)

    Liguo Wang

    2016-06-01

    Full Text Available In this paper, a generic coordinated control method for wave energy converters is proposed, and the constraints on motion amplitudes and the hydrodynamic interaction between converters are considered. The objective of the control problem is to maximize the energy converted from ocean waves, and this is achieved by coordinating the power take-off (PTO damping of each wave energy converter in the frequency domain in each sea state. In a case study, a wave energy farm consisting of four converters based on the concept developed by Uppsala University is studied. In the solution, motion constraints, including constraints on the amplitudes of displacement and velocity, are included. Twelve months of sea states, based on measured wave data at the Lysekil test site on the Swedish west coast, are used in the simulation to evaluate the performance of the wave energy farm using the new method. Results from the new coordinated control method and traditional control method are compared, indicating that the coordinated control of wave energy converters is an effective way to improve the energy production of wave energy farm in harmonic waves.

  4. Parametric study of minimum converter loss in an energy-storage dc-to-dc converter

    Science.gov (United States)

    Wong, R. C.; Owen, H. A., Jr.; Wilson, T. G.

    1982-01-01

    Through a combination of analytical and numerical minimization procedures, a converter design that results in the minimum total converter loss (including core loss, winding loss, capacitor and energy-storage-reactor loss, and various losses in the semiconductor switches) is obtained. Because the initial phase involves analytical minimization, the computation time required by the subsequent phase of numerical minimization is considerably reduced in this combination approach. The effects of various loss parameters on the optimum values of the design variables are also examined.

  5. Concept Study of Foundation Systems for Wave Energy Converters

    DEFF Research Database (Denmark)

    Molina, Salvador Devant; Vaitkunaite, Evelina; Ibsen, Lars Bo

    Analysis of possible foundation solution for Wave Energy Converters (WEC) is presented by investigating and optimizing novel foundation systems recently developed for offshore wind turbines. Gravity based, pile and bucket foundations are innovative foundation systems that are analyzed. Concept...

  6. Generators for gearless wind energy converters

    Energy Technology Data Exchange (ETDEWEB)

    Grauers, A. [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Electric Power Engineering

    1996-12-01

    This paper discusses some design alternatives for directly driven generators, and one specific generator type is investigated for a wide range of rated power. First, the specification for a directly driven generator is presented, then different design alternatives are discussed. A radial-flux permanent magnet generator for frequency converter connection has been chosen for a more detailed investigation. The design, optimization and performance of that generator type are presented. Generators from 30 kW to 3 MW are designed and compared with conventional four-pole generators with gear. It is found that a directly driven generator can be more efficient than a conventional generator and gear and have a rather small diameter and a low active weight. 8 refs, 7 figs, 2 tabs

  7. Experimental Study on the Langlee Wave Energy Converter

    DEFF Research Database (Denmark)

    Lavelle, John; Kofoed, Jens Peter

    This report concerns the experimental study of the 1:20 scale model of the Langlee Wave Energy Converter (WEC) carried out at Aalborg University’s wave basin during the summer of 2010.......This report concerns the experimental study of the 1:20 scale model of the Langlee Wave Energy Converter (WEC) carried out at Aalborg University’s wave basin during the summer of 2010....

  8. Wave Dragon Wave Energy Converters Used as Coastal Protection

    DEFF Research Database (Denmark)

    Nørgaard, Jørgen Harck; Andersen, Thomas Lykke; Kofoed, Jens Peter

    2011-01-01

    This paper deals with wave energy converters used to reduce the wave height along shorelines. For this study the Wave Dragon wave energy converter is chosen. The wave height reduction from a single device has been evaluated from physical model tests in scale 1:51.8 of the 260 x 150 m, 24 kW/m model...... Spain, to evaluate the potential for reducing wave heights close the shore by means of Wave Dragons....

  9. Moving core beam energy absorber and converter

    Science.gov (United States)

    Degtiarenko, Pavel V.

    2012-12-18

    A method and apparatus for the prevention of overheating of laser or particle beam impact zones through the use of a moving-in-the-coolant-flow arrangement for the energy absorbing core of the device. Moving of the core spreads the energy deposition in it in 1, 2, or 3 dimensions, thus increasing the effective cooling area of the device.

  10. Practical performances of MPC for wave energy converters

    DEFF Research Database (Denmark)

    Ferri, Francesco; Tetu, Amelie; Hals, J.

    2016-01-01

    Maximising the efficiency of Wave Energy Converter (WEC) is one of the important tasks toward the exploitation of the wave energy resource. Along with a proper design of the device, an important way to achieve better energy performances is to improve the wave-body interaction by applying an appro...

  11. Experimental Study of the Weptos Wave Energy Converter

    DEFF Research Database (Denmark)

    Pecher, Arthur; Kofoed, Jens Peter; Larsen, Tommy

    2012-01-01

    This paper presents the power performance results of the experimental study of the WEPTOS wave energy converter (WEC). This novel device combines an established and efficient wave energy absorbing mechanism with an adjustable structure that can regulate the amount of incoming wave energy and redu...

  12. Wave-to-wire Modelling of Wave Energy Converters

    DEFF Research Database (Denmark)

    Ferri, Francesco

    , but talking about renewable energy partially ravels the problem out. Wave energy is a large, mostly untapped, renewable energy resource. It has the potential to contribute significantly to the future energy mix, but the sector has not yet rolled off into the market in consequence of a number of technical...... and non-technical issues. These can be efficiently summarised in the cost of the energy produced by the various wave energy converters: If compared with other renewable energy technologies the cost of energy from the ocean waves is still significantly higher. Holding the comparison it also important...... to noticed that there is not a clear front runner in the wave energy sector, which fades effort and funding over a too broad frame. In order to assist efficient development and analysis of wave energy converters and therefore to accelerate the sector progression towards commercialisation, a generally...

  13. International Energy Agency Ocean Energy Systems Task 10 Wave Energy Converter Modeling Verification and Validation

    DEFF Research Database (Denmark)

    Wendt, Fabian F.; Yu, Yi-Hsiang; Nielsen, Kim

    2017-01-01

    This is the first joint reference paper for the Ocean Energy Systems (OES) Task 10 Wave Energy Converter modeling verification and validation group. The group is established under the OES Energy Technology Network program under the International Energy Agency. OES was founded in 2001 and Task 10 ...

  14. Single stage grid converters for battery energy storage

    DEFF Research Database (Denmark)

    Trintis, Ionut; Munk-Nielsen, Stig; Teodorescu, Remus

    2010-01-01

    Integration of renewable energy systems in the power system network such as wind and solar is still a challenge in our days. Energy storage systems (ESS) can overcome the disadvantage of volatile generation of the renewable energy sources. This paper presents power converters for battery energy...... storage systems (BESS) which can interface mediumvoltage batteries to the grid. Converter topologies comparison is performed in terms of efficiency, common mode voltage and redundancy for a 6kV series connected medium voltage batteries with a nominal power of 5MVA to act as a battery charger/discharger....

  15. Modeling In-stream Tidal Energy Extraction and Its Potential Environmental Impacts

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zhaoqing; Wang, Taiping; Copping, Andrea; Geerlofs, Simon H.

    2014-09-30

    In recent years, there has been growing interest in harnessing in-stream tidal energy in response to concerns of increasing energy demand and to mitigate climate change impacts. While many studies have been conducted to assess and map tidal energy resources, efforts for quantifying the associated potential environmental impacts have been limited. This paper presents the development of a tidal turbine module within a three-dimensional unstructured-grid coastal ocean model and its application for assessing the potential environmental impacts associated with tidal energy extraction. The model is used to investigate in-stream tidal energy extraction and associated impacts on estuarine hydrodynamic and biological processes in a tidally dominant estuary. A series of numerical experiments with varying numbers and configurations of turbines installed in an idealized estuary were carried out to assess the changes in the hydrodynamics and biological processes due to tidal energy extraction. Model results indicated that a large number of turbines are required to extract the maximum tidal energy and cause significant reduction of the volume flux. Preliminary model results also indicate that extraction of tidal energy increases vertical mixing and decreases flushing rate in a stratified estuary. The tidal turbine model was applied to simulate tidal energy extraction in Puget Sound, a large fjord-like estuary in the Pacific Northwest coast.

  16. Wave Energy Converter Annual Energy Production Uncertainty Using Simulations

    Directory of Open Access Journals (Sweden)

    Clayton E. Hiles

    2016-09-01

    Full Text Available Critical to evaluating the economic viability of a wave energy project is: (1 a robust estimate of the electricity production throughout the project lifetime and (2 an understanding of the uncertainty associated with said estimate. Standardization efforts have established mean annual energy production (MAEP as the metric for quantification of wave energy converter (WEC electricity production and the performance matrix approach as the appropriate method for calculation. General acceptance of a method for calculating the MAEP uncertainty has not yet been achieved. Several authors have proposed methods based on the standard engineering approach to error propagation, however, a lack of available WEC deployment data has restricted testing of these methods. In this work the magnitude and sensitivity of MAEP uncertainty is investigated. The analysis is driven by data from simulated deployments of 2 WECs of different operating principle at 4 different locations. A Monte Carlo simulation approach is proposed for calculating the variability of MAEP estimates and is used to explore the sensitivity of the calculation. The uncertainty of MAEP ranged from 2%–20% of the mean value. Of the contributing uncertainties studied, the variability in the wave climate was found responsible for most of the uncertainty in MAEP. Uncertainty in MAEP differs considerably between WEC types and between deployment locations and is sensitive to the length of the input data-sets. This implies that if a certain maximum level of uncertainty in MAEP is targeted, the minimum required lengths of the input data-sets will be different for every WEC-location combination.

  17. Energy Savings Assessment for Digital-to-Analog Converter Boxes

    Energy Technology Data Exchange (ETDEWEB)

    Cheung, Hoi Ying Iris; Meier, Alan; Brown, Richard

    2011-01-18

    The Digital Television (DTV) Converter Box Coupon Program was administered by the U.S. government to subsidize purchases of digital-to-analog converter boxes, with up to two $40 coupons for each eligible household. In order to qualify as Coupon Eligible Converter Boxes (CECBs), these devices had to meet a number of minimum performance specifications, including energy efficiency standards. The Energy Star Program also established voluntary energy efficiency specifications that are more stringent than the CECB requirements. In this study, we measured the power and energy consumptions for a sample of 12 CECBs (including 6 Energy Star labeled models) in-use in homes and estimated aggregate energy savings produced by the energy efficiency policies. Based on the 35 million coupons redeemed through the end of the program, our analysis indicates that between 2500 and 3700 GWh per year are saved as a result of the energy efficiency policies implemented on digital-to-analog converter boxes. The energy savings generated are equivalent to the annual electricity use of 280,000 average US homes.

  18. Minimising the lifetime carbon and energy intensities of the Oyster wave energy converter

    OpenAIRE

    Steynor, Jeffrey Robert

    2014-01-01

    Converting energy from ocean waves is an exciting concept aimed at reducing our dependency on fossil fuels. Ocean energy devices must convert the large forces and relatively small movements from ocean waves into electrical power with a minimum carbon and energy intensity in order to be economically viable. The research herein focuses on the Oyster, a flap-type pitching wave energy converter developed by Aquamarine Power. A device that has the minimal carbon or energy intensi...

  19. Model Predictive Control of Buoy Type Wave Energy Converter

    DEFF Research Database (Denmark)

    Soltani, Mohsen N.; Sichani, Mahdi T.; Mirzaei, Mahmood

    2014-01-01

    The paper introduces the Wavestar wave energy converter and presents the implementation of model predictive controller that maximizes the power generation. The ocean wave power is extracted using a hydraulic electric generator which is connected to an oscillating buoy. The power generator...... is an additive device attached to the buoy which may include damping, stiffness or similar terms hence will affect the dynamic motion of the buoy. Therefore such a device can be seen as a closed-loop controller. The objective of the wave energy converter is to harvest as much energy from sea as possible....... This approach is then taken into account and an MPC controller is designed for a model wave energy converter and implemented on a numerical example. Further, the power outtake of this controller is compared to the optimal controller as an indicator of the performance of the designed controller....

  20. Nanogenerators Convert Mechanical Energy into Electricity

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ Nano-devices are at the most active research frontier in today's world thanks to their unmatched features such as miniature dimension, lowenergy consumption, high sensitivity in performance. Researchers have developed a broad range of nanodevices with various applications including in situ, real-time biomedical monitoring and detection,but their use has been limited by the sources of energy available to power them. Conventional batteries make the nanoscale systems too large, and the toxic contents of batteries limit their use in human body.

  1. Converting energy to medical progress [nuclear medicine

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-04-01

    For over 50 years the Office of Biological and Environmental Research (BER) of the United States Department of Energy (DOE) has been investing to advance environmental and biomedical knowledge connected to energy. The BER Medical Sciences program fosters research to develop beneficial applications of nuclear technologies for medical diagnosis and treatment of many diseases. Today, nuclear medicine helps millions of patients annually in the United States. Nearly every nuclear medicine scan or test used today was made possible by past BER-funded research on radiotracers, radiation detection devices, gamma cameras, PET and SPECT scanners, and computer science. The heart of biological research within BER has always been the pursuit of improved human health. The nuclear medicine of tomorrow will depend greatly on today's BER-supported research, particularly in the discovery of radiopharmaceuticals that seek specific molecular and genetic targets, the design of advanced scanners needed to create meaningful images with these future radiotracers, and the promise of new radiopharmaceutical treatments for cancers and genetic diseases.

  2. Converting Energy to Medical Progress [Nuclear Medicine

    Science.gov (United States)

    2001-04-01

    For over 50 years the Office of Biological and Environmental Research (BER) of the United States Department of Energy (DOE) has been investing to advance environmental and biomedical knowledge connected to energy. The BER Medical Sciences program fosters research to develop beneficial applications of nuclear technologies for medical diagnosis and treatment of many diseases. Today, nuclear medicine helps millions of patients annually in the United States. Nearly every nuclear medicine scan or test used today was made possible by past BER-funded research on radiotracers, radiation detection devices, gamma cameras, PET and SPECT scanners, and computer science. The heart of biological research within BER has always been the pursuit of improved human health. The nuclear medicine of tomorrow will depend greatly on today's BER-supported research, particularly in the discovery of radiopharmaceuticals that seek specific molecular and genetic targets, the design of advanced scanners needed to create meaningful images with these future radiotracers, and the promise of new radiopharmaceutical treatments for cancers and genetic diseases.

  3. Experiments on the WavePiston, Wave Energy Converter

    DEFF Research Database (Denmark)

    Angelelli, E.; Zanuttigh, B.; Kofoed, Jens Peter

    2011-01-01

    This paper analyses the performance of a new Wave Energy Converter (WEC) of the Oscillating Water Column type (OWC), named WavePiston. This near-shore floating device is composed of plates (i.e. energy collectors) sliding around a cylinder, that is placed perpendicular to the shore. Tests...

  4. An Appraisal of the DEXA Wave Energy Converter

    DEFF Research Database (Denmark)

    Pecher, Arthur; Kofoed, Jens Peter

    This report has been requested by VækstFonden and aims at giving an overview of the experimental tests and a general appraisal of the DEXA wave energy converter (WEC). The reported results and findings were obtained during previously performed experimental tests by the Wave Energy Research Group...

  5. EB Frond wave energy converter - phase 2

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-07-01

    The EB Frond project is a wave energy programme developed by The Engineering Business (EB) from an original idea at Lancaster University. The EB Frond is a wave generator with a collector vane on top of an arm that pivots near the seabed. Phase 1 of the project demonstrated the technical feasibility of the project and provided proof of concept. Phase 2 involved further assesment of the technical and commercial viability of the concept through the development of mathematical and physical modelling methods. The work involved small-scale (1/25th) testing in wave tanks at Newcastle and Lancaster Universities and the development, verification and validation of a time domain mathematical model. The decision by EB to put on hold its renewable generation programme meant that plans to test at an intermediate scale (1/16th), assess different survival strategies in extreme wave conditions, carry out site characterisation for full-scale systems and to produce a robust economic model were not fulfilled. However, the mathematical and physical modelling work was used to develop an economic model for the Frond system. This produced a predicted unit cost of electricity by a pre-commercial 5 MW demonstration farm of about 17 pence/kWh. The report discusses the small-scale testing, test results, mathematical modelling, analysis and interpretation, survivability, the economic model and the development route to full-scale production.

  6. On the dynamics of a novel ocean wave energy converter

    KAUST Repository

    Orazov, B.

    2010-11-01

    Buoy-type ocean wave energy converters are designed to exhibit resonant responses when subject to excitation by ocean waves. A novel excitation scheme is proposed which has the potential to improve the energy harvesting capabilities of these converters. The scheme uses the incident waves to modulate the mass of the device in a manner which amplifies its resonant response. To illustrate the novel excitation scheme, a simple one-degree of freedom model is developed for the wave energy converter. This model has the form of a switched linear system. After the stability regime of this system has been established, the model is then used to show that the excitation scheme improves the power harvesting capabilities by 2565 percent even when amplitude restrictions are present. It is also demonstrated that the sensitivity of the device\\'s power harvesting capabilities to changes in damping becomes much smaller when the novel excitation scheme is used. © 2010 Elsevier Ltd. All rights reserved.

  7. Prototype Testing of the Wave Energy Converter Wave Dragon

    DEFF Research Database (Denmark)

    Kofoed, Jens Peter; Frigaard, Peter; Friis-Madsen, Erik

    2006-01-01

    The Wave Dragon is an offshore wave energy converter of the overtopping type. It consists of two wave reflectors focusing the incoming waves towards a ramp, a reservoir for collecting the overtopping water and a number of hydro turbines for converting the pressure head into power. In the period...... from 1998 to 2001 extensive wave tank testing on a scale model was carried at Aalborg University. Then, a 57!27 m wide and 237 tonnes heavy (incl. ballast) prototype of the Wave Dragon, placed in Nissum Bredning, Denmark, was grid connected in May 2003 as the world’s first offshore wave energy...

  8. Prototype Testing of the Wave Energy Converter Wave Dragon

    DEFF Research Database (Denmark)

    Kofoed, Jens Peter; Frigaard, Peter Bak; Friis-Madsen, Erik

    2004-01-01

    The Wave Dragon is an offshore wave energy converter of the overtopping type. It consists of two wave reflectors focusing the incoming waves towards a ramp, a reservoir for collecting the overtopping water and a number of hydro turbines for converting the pressure head into power. In the period...... from 1998 to 2001 extensive wave tank testing on a scale model was carried at Aalborg University. Then, a 57 x 27 m wide and 237 tonnes heavy (incl. ballast) prototype of the Wave Dragon, placed in Nissum Bredning, Denmark, was grid connected in May 2003 as the world's first offshore wave energy...

  9. Structural Modeling and Analysis of a Wave Energy Converter

    DEFF Research Database (Denmark)

    Zurkinden, Andrew Stephen; Lambertsen, Søren Heide; Damkilde, Lars

    2012-01-01

    A fatigue analysis is being carried out for a wave energy converter subjected to ocean wave loads. The device is a bottom fixed structure, located in a shallow water environment. Interest is focused on the local stress response of a structural detail and a subsequent calculation of its fatigue life...... by using the rainflow counting approach. The wave energy converter is characterized by its ability to enter in a storm protection mode which - whenever extreme conditions occur - will drastically reduce the exposure to wave loads. The predicted fatigue life is calculated for two different control cases...

  10. Meta-analysis: abundance, behavior, and hydraulic energy shape biotic effects on sediment transport in streams.

    Science.gov (United States)

    Albertson, L K; Allen, D C

    2015-05-01

    An increasing number of studies have emphasized the need to bridge the disciplines of ecology and geomorphology. A large number of case studies show that organisms can affect erosion, but a comprehensive understanding of biological impacts on sediment transport conditions is still lacking. We use meta-analysis to synthesize published data to quantify the effects of the abundance, body size, and behavior of organisms on erosion in streams. We also explore the influence of current velocity, discharge, and sediment grain size on the strength of biotic effects on erosion. We found that species that both increase erosion (destabilizers) and decrease erosion (stabilizers) can alter incipient sediment motion, sediment suspension, and sediment deposition above control conditions in which the organisms were not present. When abundance was directly manipulated, these biotic effects were consistently stronger in the higher abundance treatment, increasing effect sizes by 66%. Per capita effect size and per capita biomass were also consistently positively correlated. Fish and crustaceans were the most studied organisms, but aquatic insects increased the effect size by 550 x compared to other types of organisms after accounting for biomass. In streams with lower discharge and smaller grain sizes, we consistently found stronger biotic effects. Taken collectively, these findings provide synthetic evidence that biology can affect physical processes in streams, and these effects can be mediated by hydraulic energy. We suggest that future studies focus on understudied organisms, such as biofilms, conducting experiments under realistic field conditions, and developing hypotheses for the effect of biology on erosion and velocity currents in the context of restoration to better understand the forces that mediate physical disturbances in stream ecosystems.

  11. Hydraulic Evaluation of the Crest Wing Wave Energy Converter

    DEFF Research Database (Denmark)

    Kofoed, Jens Peter; Antonishen, Michael Patrick

    This report presents the results of an experimental study of the wave energy converting abilities of the Crest Wing wave energy converter (WEC). The Crest Wing is a WEC that uses its movement in matching the shape of an oncoming wave to generate power. Model tests have been performed using a scale...... model (length scale 1:30), provided by WaveEnergyFyn, in regular and irregular wave states that can be found in Assessment of Wave Energy Devices. Best Practice as used in Denmark (Frigaard et al., 2008). The tests were carried out at Dept. of Civil Engineering, Aalborg (Frigaard et al., 2008......). The tests were carried out at Dept. of Civil Engineering, Aalborg University (AAU) in the 3D deep water wave tank. The displacement and force applied to a power take off system, provided by WaveEnergyFyn, were measured and used to calculate total power take off....

  12. Experimental Study of the WEPTOS Wave Energy Converter

    DEFF Research Database (Denmark)

    Pecher, Arthur; Kofoed, Jens Peter; Marchalot, Tanguy

    This report presents the results of an experimental study on the power conversion capabilities and structural loads of the WEPTOS wave energy converter. The investigation focuses mainly at identifying the performance of the WEPTOS prototype in a wide range of production wave states and at the moo...

  13. Experimental Study on a Rotor for WEPTOS Wave Energy Converter

    DEFF Research Database (Denmark)

    Pecher, Arthur; Kofoed, Jens Peter; Marchalot, Tanguy

    This report presents the results of an experimental study of the power conversion capabilities of one single rotor of the WEPTOS wave energy converter. The investigation focuses mainly on defining the optimal weight distribution in the rotor in order to improve the hydraulic performance through...

  14. Hydraulic Evaluation of the LEANCON Wave Energy Converter

    DEFF Research Database (Denmark)

    Kofoed, Jens Peter; Frigaard, Peter

    This report is a product of the co-operation agreement between Aalborg University and LEANCON (by Kurt Due Rasmussen) on the evaluation and development of the LEANCON wave energy converter (WEC). The work reported here has focused on evaluation of the power production of the device, based...

  15. Experimental testing of moorings for large floating wave energy converters

    DEFF Research Database (Denmark)

    Thomsen, Jonas Bjerg; Ferri, Francesco; Kofoed, Jens Peter

    2016-01-01

    This paper presents the outcome of a test campaign, which investigates the behaviour of a synthetic mooring system applied to the Floating Power Plant wave energy converter. The study investigates the motion and tension response under operational and extreme sea states expected at the deployment...

  16. Optimization of Overtopping Wave Energy Converters by Geometry Control

    DEFF Research Database (Denmark)

    Victor, L.; Troch, P.; Kofoed, Jens Peter

    2011-01-01

    In this paper, the results of a study on the effects of geometry control on the performance of overtopping wave energy converters with a simple geometry built in coastal structures (simple OWECs) are presented. Empirical formulae, derived based on experimental tests on simple OWECs with varying...

  17. Experimental testing of moorings for large floating wave energy converters

    DEFF Research Database (Denmark)

    Thomsen, Jonas Bjerg; Ferri, Francesco; Kofoed, Jens Peter

    2016-01-01

    This paper presents the outcome of a test campaign, which investigates the behaviour of a synthetic mooring system applied to the Floating Power Plant wave energy converter. The study investigates the motion and tension response under operational and extreme sea states expected at the deployment ...

  18. Rectenna that converts infrared radiation to electrical energy

    Science.gov (United States)

    Davids, Paul; Peters, David W.

    2016-09-06

    Technologies pertaining to converting infrared (IR) radiation to DC energy are described herein. In a general embodiment, a rectenna comprises a conductive layer. A thin insulator layer is formed on the conductive layer, and a nanoantenna is formed on the thin insulator layer. The thin insulator layer acts as a tunnel junction of a tunnel diode.

  19. Experimental Study on A Pendulum Wave Energy Converter

    Institute of Scientific and Technical Information of China (English)

    QIU Shou-qiang; YE Jia-wei; WANG Dong-jiao; LIANG Fu-lin

    2013-01-01

    Many of the existing wave energy converters (WEC) are of oscillating water column (OWC) and point absorber (PA) types.Fewer references have been published in public on the pendulum type WEC.A series of experimental tests on a bottom-hinged pendulum WEC model are carried out and some results are revealed in the present study.The purpose of this paper is to present a detailed description of the tests.It is found that wave energy conversion efficiency varies with the applied damping and wave conditions.In addition,special attention is given to the effect of the water ballast on the efficiency of the wave energy converter.It is demonstrated that the ballast plays an important role in energy extraction.Better understanding on how the performance of the device is influenced by damping,wave height,wave period and ballast is shown.

  20. On Mooring Solutions for Large Wave Energy Converters

    DEFF Research Database (Denmark)

    Thomsen, Jonas Bjerg; Kofoed, Jens Peter; Ferri, Francesco

    2017-01-01

    The present paper describes the work carried out in the project ’Mooring Solutions for Large Wave Energy Converters’, which is a Danish research project carried out in a period of three years from September 2014, with the aim of reducing cost of the moorings for four wave energy converters......-model based optimization process with the aim of optimizing the mooring layout for each WEC according to cost of the systems....

  1. Energy Capture Optimization for an Adaptive Wave Energy Converter

    NARCIS (Netherlands)

    Barradas Berglind, Jose de Jesus; Meijer, Harmen; van Rooij, Marijn; Clemente Pinol, Silvia; Galvan Garcia, Bruno; Prins, Wouter; Vakis, Antonis I.; Jayawardhana, Bayu

    2016-01-01

    Wave energy has great potential as a renewable energy source, and can therefore contribute significantly to the proportion of renewable energy in the global energy mix. This is especially important since energy mixes with high renewable penetration have become a worldwide priority. One solution to f

  2. Development of the Wave Energy Converter -Wave Dragon

    DEFF Research Database (Denmark)

    Kofoed, Jens Peter; Frigaard, Peter; Sørensen, Hans Christian;

    2000-01-01

    2Over the years wave energy has gradually been brought into focus, as it has become clear that the fossil energy resources are limited, and cause large environmental problems, e.g. CO2 pollution. On this background a number of different wave energy converters have been proposed. In Denmark...... the government have decided to appropriate 20 mill. DKK (approx. 2,7 mill. EUR) to the development of wave energy devices over two years, 1998-1999, and the European Community (EC) also supports the development through the JOULECRAFT program....

  3. Model Predictive Control of a Wave Energy Converter

    DEFF Research Database (Denmark)

    Andersen, Palle; Pedersen, Tom Søndergård; Nielsen, Kirsten Mølgaard;

    2015-01-01

    In this paper reactive control and Model Predictive Control (MPC) for a Wave Energy Converter (WEC) are compared. The analysis is based on a WEC from Wave Star A/S designed as a point absorber. The model predictive controller uses wave models based on the dominating sea states combined with a model...... connecting undisturbed wave sequences to sequences of torque. Losses in the conversion from mechanical to electrical power are taken into account in two ways. Conventional reactive controllers are tuned for each sea state with the assumption that the converter has the same efficiency back and forth. MPC...

  4. Current Source Converter Based Wind Energy Conversion Systems

    Institute of Scientific and Technical Information of China (English)

    Samir Kouro; Jing-ya DAI; Bin WU

    2011-01-01

    The increase in the installed capacity of wind energy conversion systems (WECS) has triggered the development of more demanding grid codes and additional requirements on performance.In order to meet these requirements the industry trend has shifted to full-scale power converter interfaces in modern multi-megawatt WECS.As consequence,a wide variety of new power converter topologies and WECS configurations have been introduced in recent years.Among them,current source converter(CSC) based configurations have attracted attention due to a series of advantages like:simple structure,grid friendly waveforms,controllable power factor,and reliable grid short-circuit protection.This paper presents the latest developments in CSC interfaces for WECS and related technologies such as modulation methods,control schemes and grid code compatibility.

  5. Stochastic control of inertial sea wave energy converter.

    Science.gov (United States)

    Raffero, Mattia; Martini, Michele; Passione, Biagio; Mattiazzo, Giuliana; Giorcelli, Ermanno; Bracco, Giovanni

    2015-01-01

    The ISWEC (inertial sea wave energy converter) is presented, its control problems are stated, and an optimal control strategy is introduced. As the aim of the device is energy conversion, the mean absorbed power by ISWEC is calculated for a plane 2D irregular sea state. The response of the WEC (wave energy converter) is driven by the sea-surface elevation, which is modeled by a stationary and homogeneous zero mean Gaussian stochastic process. System equations are linearized thus simplifying the numerical model of the device. The resulting response is obtained as the output of the coupled mechanic-hydrodynamic model of the device. A stochastic suboptimal controller, derived from optimal control theory, is defined and applied to ISWEC. Results of this approach have been compared with the ones obtained with a linear spring-damper controller, highlighting the capability to obtain a higher value of mean extracted power despite higher power peaks.

  6. Practical performances of MPC for wave energy converters

    DEFF Research Database (Denmark)

    Ferri, Francesco; Tetu, Amelie; Hals, J.

    2016-01-01

    Maximising the efficiency of Wave Energy Converter (WEC) is one of the important tasks toward the exploitation of the wave energy resource. Along with a proper design of the device, an important way to achieve better energy performances is to improve the wave-body interaction by applying...... version (1:20) of a single floater of the Wavestar WEC: a single degree of freedom point absorber. The system was tested with regular and irregular long crested waves in the deep basing at Aalborg University, DK and results of the MPC are compared with standard resistive controller architecture...

  7. User guide – COE Calculation Tool for Wave Energy Converters

    DEFF Research Database (Denmark)

    Chozas, Julia Fernandez; Kofoed, Jens Peter; Jensen, Niels Ejner Helstrup

    Aalborg University together with Energinet.dk and Julia F. Chozas Consulting Engineer, have released a freely available online spreadsheet to evaluate the Levelised Cost of Energy (LCOE) for wave energy projects. The open-access tool calculates the LCOE based on the power production of a Wave...... Energy Converter (WEC) at a particular location. Production data may derive from laboratory testing, numerical modelling or from sea trials. The tool has been developed as a transparent and simple model that evaluates WEC’s economic feasibility in a range of locations, while scaling WEC’s features...

  8. Model Predictive Control of Buoy Type Wave Energy Converter

    DEFF Research Database (Denmark)

    Soltani, Mohsen; Sichani, Mahdi Teimouri; Mirzaei, Mahmood

    2014-01-01

    The paper introduces the Wavestar wave energy converter and presents the implementation of model predictive controller that maximizes the power generation. The ocean wave power is extracted using a hydraulic electric generator which is connected to an oscillating buoy. The power generator is an a....... This approach is then taken into account and an MPC controller is designed for a model WEC and implemented on a numerical example. Further, the power outtake of this controller is compared to the optimal controller as an indicator of the performance of the designed controller.......The paper introduces the Wavestar wave energy converter and presents the implementation of model predictive controller that maximizes the power generation. The ocean wave power is extracted using a hydraulic electric generator which is connected to an oscillating buoy. The power generator...... is an additive device attached to the buoy which may include damping, stiffness or similar terms hence will affect the dynamic motion of the buoy. Therefore such a device can be seen as a closed-loop controller. The objective of the wave energy converter is to harvest as much energy from sea as possible...

  9. Aiding Design of Wave Energy Converters via Computational Simulations

    Science.gov (United States)

    Jebeli Aqdam, Hejar; Ahmadi, Babak; Raessi, Mehdi; Tootkaboni, Mazdak

    2015-11-01

    With the increasing interest in renewable energy sources, wave energy converters will continue to gain attention as a viable alternative to current electricity production methods. It is therefore crucial to develop computational tools for the design and analysis of wave energy converters. A successful design requires balance between the design performance and cost. Here an analytical solution is used for the approximate analysis of interactions between a flap-type wave energy converter (WEC) and waves. The method is verified using other flow solvers and experimental test cases. Then the model is used in conjunction with a powerful heuristic optimization engine, Charged System Search (CSS) to explore the WEC design space. CSS is inspired by charged particles behavior. It searches the design space by considering candidate answers as charged particles and moving them based on the Coulomb's laws of electrostatics and Newton's laws of motion to find the global optimum. Finally the impacts of changes in different design parameters on the power takeout of the superior WEC designs are investigated. National Science Foundation, CBET-1236462.

  10. Experimental Study on the Langlee Wave Energy Converter

    DEFF Research Database (Denmark)

    Pecher, Arthur; Kofoed, Jens Peter; Weisz, A.

    This report presents the results of an experimental study of the wave energy converting abilities of the Langlee wave energy converter (WEC). It focused mainly on evaluating the power generating capabilities of the device, including investigations of the following issues: Scaling ratiosPTO loadingWave...... height and wave period dependencyOblique incoming waves and directional spreading of waves (3D waves)Damping platesMooring forces and fixed structure setupPitch, surge and heave motion During the study the model supplied by the client (Langlee Wave Power AS) has been heavily instrumented - up to 23...... different instruments was deployed to measure and record data. Tests were performed at scales of 1:30 and 1:20 based on the realized reference wave states....

  11. Solid state radioisotopic energy converter for space nuclear power

    Energy Technology Data Exchange (ETDEWEB)

    Brown, P.M. (IsoGen Radioisotopic Research Laboratory, 315 S. McLoughlin Blvd., Oregon City, Oregon 97045 (United States))

    1993-01-10

    Recent developments in materials technology now make it possible to fabricate nonthermal thin-film radioisotopic energy converters (REC) with a specific power of 24 W/kg and a 10 year working life at 5 to 10 watts. This creates applications never before possible, such as placing the power supply directly on integrated circuit chips. The efficiency of the REC is about 25% which is two to three times greater than the 6 to 8% capabilities of current thermoelectric systems. Radioisotopic energy converters have the potential to meet many future space power requirements for a wide variety of applications with less mass, better efficiency, and less total area than other power conversion options. These benefits result in significant dollar savings over the projected mission lifetime.

  12. Nine Level Inverter with Boost Converter from Renewable Energy Source

    Directory of Open Access Journals (Sweden)

    Maruthu Pandiyan.R

    2015-01-01

    Full Text Available A new single phase nine level multilevel inverter is proposed. The input to the proposed nine level multilevel inverter is obtained from solar panel . The solar energy obtained from the solar panel is not constant and it varies with times. In order to maintain the constant voltage obtained from the solar panel the boost converter is used to maintain the constant output voltage using MPPT ( Perturb and observe algorithm algorithm. Then the buck boost converter output voltage is stored in the battery bank. Finally the battery energy is connected to the 9 level inverter circuits. The harmonics in the inverter is eliminated by using the fuzzy logic controller. The gate pulse for the multilevel inverter is given by the fuzzy logic controller which in turn reduces the harmonics in the inverter. Then the inverter output is connected to the grid are some application.

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

    Directory of Open Access Journals (Sweden)

    Zanxiang Nie

    2017-01-01

    Full Text Available 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.

  14. Trimode Power Converter optimizes PV, diesel and battery energy sources

    Science.gov (United States)

    Osullivan, George; Bonn, Russell; Bower, Ward

    1994-12-01

    Conservatively, there are 100,000 localities in the world waiting for the benefits that electricity can provide, and many of these are in climates where sunshine is plentiful. With these locations in mind a prototype 30 kW hybrid system has been assembled at Sandia to prove the reliability and economics of photovoltaic, diesel and battery energy sources managed by an autonomous power converter. In the Trimode Power Converter the same power parts, four IGBT's with an isolation transformer and filter components, serve as rectifier and charger to charge the battery from the diesel; as a stand-alone inverter to convert PV and battery energy to AC; and, as a parallel inverter with the diesel-generator to accommodate loads larger than the rating of the diesel. Whenever the diesel is supplying the load, an algorithm assures that the diesel is running at maximum efficiency by regulating the battery charger operating point. Given the profile of anticipated solar energy, the cost of transporting diesel fuel to a remote location and a five year projection of load demand, a method to size the PV array, battery and diesel for least cost is developed.

  15. A Method for EIA Scoping of Wave Energy Converters

    DEFF Research Database (Denmark)

    Margheritini, Lucia; Hansen, Anne Merrild; Frigaard, Peter

    2012-01-01

    During the first decade of the 21st Century the World faces spread concern for global warming caused by rise of green house gasses produced mainly by combustion of fossil fuels. Under this latest spin all renewable energies run parallel in order to achieve sustainable development. Among them wave...... energy has an unequivocal potential and technology is ready to enter the market and contribute to the renewable energy sector. Yet, frameworks and regulations for wave energy development are not fully ready, experiencing a setback caused by lack of understanding of the interaction of the technologies....... This paper presents the development of a classification of wave energy converters that is based on the different impact the technologies are expected to have on the environment. This innovative classification can be used in order to simplify the scoping process for developers and authorities....

  16. Structural Reliability of Plain Bearings for Wave Energy Converter Applications

    DEFF Research Database (Denmark)

    Ambühl, Simon; Kramer, Morten Mejlhede; Sørensen, John Dalsgaard

    2016-01-01

    The levelized cost of energy (LCOE) from wave energy converters (WECs) needs to be decreased in order to be able to become competitive with other renewable electricity sources. Probabilistic reliability methods can be used to optimize the structure of WECs. Optimization is often performed...... the hydraulic cycle when waves are passing. The new PTO system leads to different load characteristics at the floater itself compared to the actual setup where the turbine/generator is directly coupled to the fluctuating hydraulic pressure within the PTO system. This paper calculates the structural reliability...

  17. Reliability-Based Structural Optimization of Wave Energy Converters

    DEFF Research Database (Denmark)

    Ambühl, Simon; Kramer, Morten; Sørensen, John Dalsgaard

    2014-01-01

    More and more wave energy converter (WEC) concepts are reaching prototype level. Once the prototype level is reached, the next step in order to further decrease the levelized cost of energy (LCOE) is optimizing the overall system with a focus on structural and maintenance (inspection) costs......, as well as on the harvested power from the waves. The target of a fully-developed WEC technology is not maximizing its power output, but minimizing the resulting LCOE. This paper presents a methodology to optimize the structural design of WECs based on a reliability-based optimization problem...

  18. Testing, Analysis and Control of Wave Dragon, Wave Energy Converter

    DEFF Research Database (Denmark)

    Tedd, James

    of a textbook, a submitted journal paper and three peer-reviewed conference papers. The content can be broadly divided into four topics: experiences gained with the Wave Dragon prototype device; power-production verification; overtopping analysis; and improvements in control. A comprehensive record...... the expected performance. Other sources of generation are presented, including development and tank testing of a novel power absorbing joint. Wave Dragon belongs in the family of overtopping wave energy converters. The energy is captured by waves running up a ramp and overtopping the crest into a reservoir...

  19. Prototype device for converting freezing energy into mechanical work

    Energy Technology Data Exchange (ETDEWEB)

    Habeebullah, B.; Zaki, G.M.; Akyurt, M. [Fakieh Center for Applied Research, Makkah Al-Mukarramah (Saudi Arabia)

    2003-01-01

    Certain properties of ice are reviewed. The phenomenon of freezing of water is discussed, with special emphasis on the blockage and bursting of water pipes. Several concepts are discussed that are related to achieving the freezing of water, the design of the container where freezing occurs and the conversion into mechanical energy. A conceptual design is presented for one type of ice energy converter. Certain design details for this machine are provided. Initial test results are furnished for this device, which was manufactured and tested. Conclusions are drawn and recommendations are made. (author)

  20. Modeling and Simulation of a Wave Energy Converter INWAVE

    OpenAIRE

    Seung Kwan Song; Yong Jun Sung; Jin Bae Park

    2017-01-01

    INGINE Inc. developed its own wave energy converter (WEC) named INWAVE and has currently installed three prototype modules in Jeju Island, Korea. This device is an on-shore-type WEC that consists of a buoy, pulleys fixed to the sea-floor and a power take off module (PTO). Three ropes are moored tightly on the bottom of the buoy and connected to the PTO via the pulleys, which are moving back and forth according to the motion of the buoy. Since the device can harness wave energy from all six de...

  1. A Design Outline for Floating Point Absorber Wave Energy Converters

    Directory of Open Access Journals (Sweden)

    Mohammed Faizal

    2014-04-01

    Full Text Available An overview of the most important development stages of floating point absorber wave energy converters is presented. At a given location, the wave energy resource has to be first assessed for varying seasons. The mechanisms used to convert wave energy to usable energy vary for different wave energy conversion systems. The power output of the generator will have variations due to varying incident waves. The wave structure-interaction leads to modifications in the incident waves; thus, the power output is also affected. The device has to be stable enough to prevent itself from capsizing. The point absorber will give optimum performance when the incident wave frequencies correspond to the natural frequency of the device. The methods for calculating natural frequencies for pitching and heaving systems are presented. Mooring systems maintain the point absorber at the desired location. Various mooring configurations as well as the most commonly used materials for mooring lines are discussed. An overview of scaled modelling is also presented.

  2. Prototype testing of the wave energy converter wave dragon

    Energy Technology Data Exchange (ETDEWEB)

    Kofoed, Jens Peter; Frigaard, Peter [Hydraulics and Coastal Engineering Laboratory, Department of Civil Engineering, Aalborg University, Sohngaardsholmsvej 57, Aalborg 9000 (Denmark); Friis-Madsen, Erik [Loewenmark F.R.I., Copenhagen (Denmark); Soerensen, Hans Chr. [SPOK, Copenhagen (Denmark)

    2006-02-01

    The Wave Dragon is an offshore wave energy converter of the overtopping type. It consists of two wave reflectors focusing the incoming waves towards a ramp, a reservoir for collecting the overtopping water and a number of hydro turbines for converting the pressure head into power. In the period from 1998 to 2001 extensive wave tank testing on a scale model was carried at Aalborg University. Then, a 57x27m wide and 237tonnes heavy (incl. ballast) prototype of the Wave Dragon, placed in Nissum Bredning, Denmark, was grid connected in May 2003 as the world's first offshore wave energy converter. The prototype is fully equipped with hydro turbines and automatic control systems, and is instrumented in order to monitor power production, wave climate, forces in mooring lines, stresses in the structure and movements of the Wave Dragon. In the period May 2003 to January 2005 an extensive measuring program has been carried out, establishing the background for optimal design of the structure and regulation of the power take off system. Planning for deployment of a 4MW power production unit in the Atlantic by 2007 is in progress. (author)

  3. CONVERSION EFFICIENCY IMPROVEMENT FOR ENERGY CONSERVATION USING MATRIX CONVERTER

    Directory of Open Access Journals (Sweden)

    G.N. SURYA

    2012-04-01

    Full Text Available Efficient conversion of electrical energy from one form to another has always been a fascinating domain for researchers. Right from the era of mercury arc rectifiers to present AC-DC-AC two stage converters and cycloconverters, efforts are consistently being laid to minimize the losses involved in conversion process. In the present study the AC-AC conversion topology known as Matrix Converter (MC, is modeled using MATLAB. Venturini’s simplified algorithm is used to determine the switch modulation duty cycle. The model is designedfor conversion of 50 Hz input frequency to 100 Hz and 25 Hz, using a simplified switch modulation strategy. The waveforms generated by MATLAB/simulink confirm the reduction of conversion losses by 12% to 15% with use of proposed model as compared to conventional (PWM converters. It is not intended in this study just to list out various works done so for but to establish the brevity of fundamental concept representing the simplified design along with its application areas mainly the VFDs and Wind Energy Conversion Systems (WECS. The model has also been tested for control of induction motor with 100 HZ and 25 Hz output frequencies. The waveforms of changed frequencies and reduced losses confirm the results anticipated at design stage.

  4. DC-DC converter for discharging energy storage magnets

    Science.gov (United States)

    Eyssa, Yehia M.; Huang, Xianrui

    1994-07-01

    A new DC-DC converter to control the output power delivered from a magnetic energy storage magnet or an equivalent current source is discussed. The circuit consists of: (1) highly coupled transformer (air or iron core) with coupling coefficient better than 0.95; (2) low frequency mechanical or superconducting switches (0.1 - 10 Hz) or high frequency (10 - 1000 Hz) GTO switches depending on the application; and (3) small voltage source (capacitor or battery) to control the output voltage. Two examples illustrating the application of this circuit are discussed. They are a step up dc current converter for use in uninterruptible power supplies and a step down one for use in discharging large current storage coil into a small current load. The efficiency expected to exceed 90%.

  5. DC Storage Energy Variation Factor Study for Switched Mode Power Converters

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The effectiveness of energy conversion in DC switched-mode power converters is studied.The ratio of the energy storage in the systemto the energy put - through is investigated for several converters.A very comprehensive study to identify how the energy is manipulatedby the various types of converters is reported in this paper.

  6. Reference Model 6 (RM6): Oscillating Wave Energy Converter.

    Energy Technology Data Exchange (ETDEWEB)

    Bull, Diana L; Smith, Chris; Jenne, Dale Scott; Jacob, Paul; Copping, Andrea; Willits, Steve; Fontaine, Arnold; Brefort, Dorian; Gordon, Margaret Ellen; Copeland, Robert; Jepsen, Richard Alan

    2014-10-01

    This report is an addendum to SAND2013-9040: Methodology for Design and Economic Analysis of Marine Energy Conversion (MEC) Technologies. This report describes an Oscillating Water Column Wave Energy Converter reference model design in a complementary manner to Reference Models 1-4 contained in the above report. In this report, a conceptual design for an Oscillating Water Column Wave Energy Converter (WEC) device appropriate for the modeled reference resource site was identified, and a detailed backward bent duct buoy (BBDB) device design was developed using a combination of numerical modeling tools and scaled physical models. Our team used the methodology in SAND2013-9040 for the economic analysis that included costs for designing, manufacturing, deploying, and operating commercial-scale MEC arrays, up to 100 devices. The methodology was applied to identify key cost drivers and to estimate levelized cost of energy (LCOE) for this RM6 Oscillating Water Column device in dollars per kilowatt-hour ($/kWh). Although many costs were difficult to estimate at this time due to the lack of operational experience, the main contribution of this work was to disseminate a detailed set of methodologies and models that allow for an initial cost analysis of this emerging technology. This project is sponsored by the U.S. Department of Energy's (DOE) Wind and Water Power Technologies Program Office (WWPTO), within the Office of Energy Efficiency & Renewable Energy (EERE). Sandia National Laboratories, the lead in this effort, collaborated with partners from National Laboratories, industry, and universities to design and test this reference model.

  7. The Force of a Tsunami on a Wave Energy Converter

    CERN Document Server

    O'Brien, Laura; Renzi, Emiliano; Dutykh, Denys; Dias, Frédéric

    2012-01-01

    With an increasing emphasis on renewable energy resources, wave power technology is fast becoming a realistic solution. However, the recent tsunami in Japan was a harsh reminder of the ferocity of the ocean. It is known that tsunamis are nearly undetectable in the open ocean but as the wave approaches the shore its energy is compressed creating large destructive waves. The question posed here is whether a nearshore wave energy converter (WEC) could withstand the force of an incoming tsunami. The analytical 3D model of Renzi & Dias (2012) developed within the framework of a linear theory and applied to an array of fixed plates is used. The time derivative of the velocity potential allows the hydrodynamic force to be calculated.

  8. Heterobarrier for converting hot-phonon energy to electric potential

    Science.gov (United States)

    Shin, Seungha; Melnick, Corey; Kaviany, Massoud

    2013-02-01

    We show that hot phonons emitted in energy conversion or resistive processes can be converted to electric potential in heterobarrier structures. Using phonon and electron interaction kinetics and self-consistent ensemble Monte Carlo, we find the favorable conditions for unassisted absorption of hot phonons and design graded heterobarriers for their direct conversion into electric energy. Tandem barriers with nearly optical-phonon height allow for substantial potential gain without current loss. We find that 19% of hot phonons can be harvested with an optimized GaAs/AlxGa1-xAs barrier structure over a range of current and electron densities, thus enhancing the overall energy conversion efficiency and reducing waste heat.

  9. WEC3: Wave Energy Converter Code Comparison Project: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Combourieu, Adrien; Lawson, Michael; Babarit, Aurelien; Ruehl, Kelley; Roy, Andre; Costello, Ronan; Laporte Weywada, Pauline; Bailey, Helen

    2017-01-01

    This paper describes the recently launched Wave Energy Converter Code Comparison (WEC3) project and present preliminary results from this effort. The objectives of WEC3 are to verify and validate numerical modelling tools that have been developed specifically to simulate wave energy conversion devices and to inform the upcoming IEA OES Annex VI Ocean Energy Modelling Verification and Validation project. WEC3 is divided into two phases. Phase 1 consists of a code-to-code verification and Phase II entails code-to-experiment validation. WEC3 focuses on mid-fidelity codes that simulate WECs using time-domain multibody dynamics methods to model device motions and hydrodynamic coefficients to model hydrodynamic forces. Consequently, high-fidelity numerical modelling tools, such as Navier-Stokes computational fluid dynamics simulation, and simple frequency domain modelling tools were not included in the WEC3 project.

  10. The TELEC - A plasma type of direct energy converter. [Thermo-Electronic Laser Energy Converter for electric power generation

    Science.gov (United States)

    Britt, E. J.

    1978-01-01

    The Thermo-Electronic Laser Energy Converter (TELEC) is a high-power density plasma device designed to convert a 10.6-micron CO2 laser beam into electric power. Electromagnetic radiation is absorbed in plasma electrons, creating a high-electron temperature. Energetic electrons diffuse from the plasma and strike two electrodes having different areas. The larger electrode collects more electrons and there is a net transport of current. An electromagnetic field is generated in the external circuit. A computer program has been designed to analyze TELEC performance allowing parametric variation for optimization. Values are presented for TELEC performance as a function of cesium pressure and for current density and efficiency as a function of output voltage. Efficiency is shown to increase with pressure, reaching a maximum over 45%.

  11. The SSG Wave Energy Converter: Performance, Status and Recent Developments

    Directory of Open Access Journals (Sweden)

    Mariano Buccino

    2012-01-01

    Full Text Available The Sea-wave Slot-cone Generator (SSG is a Wave Energy Converter based on the wave overtopping principle; it employs several reservoirs placed on top of each other, in which the energy of incoming waves is stored as potential energy. Then, the captured water runs through turbines for electricity production. The system works under a wide spectrum of different wave conditions, giving a high overall efficiency. It can be suitable for shoreline and breakwater applications and presents particular advantages, such as sharing structure costs, availability of grid connection and recirculation of water inside the harbor, as the outlet of the turbines is on the rear part of the system. Recently, plans for the SSG pilot installations are in progress at the Svaaheia site (Norway, the port of Hanstholm (Denmark and the port of Garibaldi (Oregon, USA. In the last-mentioned two projects, the Sea-wave Slot-cone Generator technology is integrated into the outer harbor breakwater and jetty reconstruction projects. In the last years extensive studies have been performed on the hydraulic and the structural response of this converter, with the aim of optimizing the design process. The investigations have been conducted by physical model tests and numerical simulations and many results have been published on both conference proceedings and journals. The main scope of this paper is reviewing the most significant findings, to provide the reader with an organic overview on the present status of knowledge.

  12. Energy iteration model research of DCM Buck converter with multilevel pulse train technique

    Science.gov (United States)

    Qin, Ming; Li, Xiang

    2017-08-01

    According as the essence of switching converter is the nature of energy, the energy iteration model of the Multilevel Pulse Train (MPT) technique is studied in this paper. The energy iteration model of DCM Buck converter with MPT technique can reflect the control law and excellent transient performance of the MPT technique. The iteration relation of energy transfer in switching converter is discussed. The structure and operation principle of DCM Buck converter with MPT technique is introduced and the energy iteration model of this converter is set up. The energy tracks of MPT-control Buck converter and PT converter is researched and compared to show that the ratio of steady-state control pulse satisfies the expectation for the MPT technique and the MPT-controlled switching converter has much lower output voltage ripple than the PT converter.

  13. Integration of Wave Energy Converters into Coastal Protection Schemes

    DEFF Research Database (Denmark)

    Zanuttigh, B.; Martinelli, L.; Castagnetti, M.

    2010-01-01

    The purpose of this paper is to examine the feasibility of using wave energy converters for coastal protection through laboratory tests. The paper considers the case of a near-shore floating device of the Wave Activated Body type, named DEXA. The influence of the device length and of the wave...... parameters on device efficiency and on inshore wave transmission are investigated. A preliminary design procedure to optimise both device efficiency and wave transmission is proposed by means of an hypothetical application to the Adriatic coast. The effects induced by the device on coastal morphology...

  14. Different Reliability Assessment Approaches for Wave Energy Converters

    DEFF Research Database (Denmark)

    Ambühl, Simon; Kramer, Morten Mejlhede; Sørensen, John Dalsgaard

    2015-01-01

    Reliability assessments are of importance for wave energy converters (WECs) due to the fact that accessibility might be limited in case of failure and maintenance. These failure rates can be adapted by reliability considerations. There are two different approaches to how reliability can...... be estimated: the so-called classical reliability theory and the probabilistic reliability theory. The classical reliability theory is often used for failure rate estimations of mechanical and electrical components, whereas the probabilistic reliability theory is commonly used for structural components...

  15. Experimental Study on the WavePiston Wave Energy Converter

    DEFF Research Database (Denmark)

    Pecher, Arthur; Kofoed, Jens Peter; Angelelli, E.

    This report presents the results of an experimental study of the power performance of the WavePiston wave energy converter. It focuses mainly on evaluating the power generating capabilities of the device and the effect of the following issues: Scaling ratios PTO loading Wave height and wave period...... dependency Oblique incoming waves Distance between plates During the study, the model supplied by the client, WavePiston, has been rigorously tested as all the anticipated tests have been done thoroughly and during all tests, good quality data has been obtained from all the sensors....

  16. Hydraulic Response of the Wave Energy Converter Wave Dragon in Nissum Bredning

    DEFF Research Database (Denmark)

    Kofoed, Jens Peter; Frigaard, Peter

    This report deals with the hydraulic performance of the wave energy converter Wave Dragon, Nissum Bredning prototype.......This report deals with the hydraulic performance of the wave energy converter Wave Dragon, Nissum Bredning prototype....

  17. Reference Model 5 (RM5): Oscillating Surge Wave Energy Converter

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Y. H. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Jenne, D. S. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Thresher, R. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Copping, A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Geerlofs, S. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Hanna, L. A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-01-01

    This report is an addendum to SAND2013-9040: Methodology for Design and Economic Analysis of Marine Energy Conversion (MEC) Technologies. This report describes an Oscillating Water Column Wave Energy Converter (OSWEC) reference model design in a complementary manner to Reference Models 1-4 contained in the above report. A conceptual design for a taut moored oscillating surge wave energy converter was developed. The design had an annual electrical power of 108 kilowatts (kW), rated power of 360 kW, and intended deployment at water depths between 50 m and 100 m. The study includes structural analysis, power output estimation, a hydraulic power conversion chain system, and mooring designs. The results were used to estimate device capital cost and annual operation and maintenance costs. The device performance and costs were used for the economic analysis, following the methodology presented in SAND2013-9040 that included costs for designing, manufacturing, deploying, and operating commercial-scale MEC arrays up to 100 devices. The levelized cost of energy estimated for the Reference Model 5 OSWEC, presented in this report, was for a single device and arrays of 10, 50, and 100 units, and it enabled the economic analysis to account for cost reductions associated with economies of scale. The baseline commercial levelized cost of energy estimate for the Reference Model 5 device in an array comprised of 10 units is $1.44/kilowatt-hour (kWh), and the value drops to approximately $0.69/kWh for an array of 100 units.

  18. Hydraulic behaviour of the floating wave energy converter Wave Dragon

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2002-07-01

    The objective of the project is to establish a scale 1:4.5 test model of the floating offshore wave energy converter - Wave Dragon - for testing at 5 m water depth in the Inlet Nissum Bredning. The test model will be equipped with an existing diameter 340 mm model turbine plus additional outlet tubes simulating the resistance from 1 - 16 turbines. The model will be designed to stay afloat even with a total loss of air pressure in the open bottom buoyancy chambers. The test series will primarily focus on measurements of hydraulic response, forces in the mooring system and overtopping quantities. Also data such as head, rotational speed and power production from the turbine will be monitored during the whole test period. The project will verify the effect of the pressured air buoyancy system, which cannot be scaled correctly in laboratory scale models. The test results will allow for an evaluation of the Wave Dragon power production as a function of sea state and freeboard height, in order to calibrate the existing WD-power simulation software. The model can be utilized for further testing of turbine regulation and stress and strain in the structure, establishing the necessary knowledge base for deploying a full-scale demonstration plant. This CD-ROM contains various videos, reports, notes, conference papers and Power Point presentations on the making of the wave energy converter Wave Dragon. (BA)

  19. Initial Assessment of Mooring Solutions for Floating Wave Energy Converters

    DEFF Research Database (Denmark)

    Thomsen, Jonas Bjerg; Kofoed, Jens Peter; Delaney, Martin

    2016-01-01

    The present study investigates three different types of mooring systems in order to establish potential cost reductions and applicability to wave energy converters (WECs). Proposed mooring systems for three existing WECs create the basis for this study, and the study highlights areas of interest ...... type system can provide a paramount cost reduction compared to a traditional CALM type system with chain lines. Similarly, use of nylon ropes similarly appears to provide low cost.......The present study investigates three different types of mooring systems in order to establish potential cost reductions and applicability to wave energy converters (WECs). Proposed mooring systems for three existing WECs create the basis for this study, and the study highlights areas of interest...... using a preliminary cost estimation and discussion of buildability issues. Using synthetic rope and variations in the mooring configuration has the potential of influencing the cost significantly. In order to quantify this potential, a simple quasi-static analysis is performed, which shows that a SALM...

  20. Wave Induced Loads on the LEANCON Wave Energy Converter

    DEFF Research Database (Denmark)

    Frigaard, Peter; Kofoed, Jens Peter; Beserra, Eliab Ricarte

    This report is a product of the co-operation agreement between Aalborg University and LEANCON (by Kurt Due Rasmussen) on the evaluation and development of the LEANCON wave energy converter (WEC). The work reported here has focused on evaluation of the wave induced loads on the device, based...... on a desktop study based on available literature, supplemented by laboratory testing of models of the WEC provided by LEANCON. LEANCON, represented by Kurt Due Rasmussen, has been heavily involved in the testing of the device, including the instrumentation, model setup and execution of the tests...... in the laboratory, all under the supervision of the personnel of the Wave Energy Research Group at Department of Civil Engineering, Aalborg University....

  1. Modeling and Simulation of a Wave Energy Converter INWAVE

    Directory of Open Access Journals (Sweden)

    Seung Kwan Song

    2017-01-01

    Full Text Available INGINE Inc. developed its own wave energy converter (WEC named INWAVE and has currently installed three prototype modules in Jeju Island, Korea. This device is an on-shore-type WEC that consists of a buoy, pulleys fixed to the sea-floor and a power take off module (PTO. Three ropes are moored tightly on the bottom of the buoy and connected to the PTO via the pulleys, which are moving back and forth according to the motion of the buoy. Since the device can harness wave energy from all six degrees of movement of the buoy, it is possible to extract energy efficiently even under low energy density conditions provided in the coastal areas. In the PTO module, the ratchet gears convert the reciprocating movement of the rope drum into a uni-directional rotation and determine the transmission of power from the relation of the angular velocities between the rope drum and the generator. In this process, the discontinuity of the power transmission occurs and causes the modeling divergence. Therefore, we introduce the concept of the virtual torsion spring in order to prevent the impact error in the ratchet gear module, thereby completing the PTO modeling. In this paper, we deal with dynamic analysis in the time domain, based on Newtonian mechanics and linear wave theory. We derive the combined dynamics of the buoy and PTO modules via geometric relation between the buoy and mooring ropes, then suggest the ratchet gear mechanism with the virtual torsion spring element to reduce the dynamic errors during the phase transitions. Time domain simulation is carried out under irregular waves that reflect the actual wave states of the installation area, and we evaluate the theoretical performance using the capture width ratio.

  2. Design Specifications for the Hanstholm WEPTOS Wave Energy Converter

    Directory of Open Access Journals (Sweden)

    Tommy Larsen

    2012-04-01

    Full Text Available The WEPTOS wave energy converter (WEC is a novel device that combines an established and efficient wave energy absorbing mechanism with a smart structure, which can regulate the amount of incoming wave energy and reduce loads in extreme wave conditions. This adjustable A-shaped slack-moored and floating structure absorbs the energy of the waves through a multitude of rotors. The shape of the rotors is based on the renowned Salter’s Duck. On each leg, the rotors pivot around a common axle, through which the rotors transfer the absorbed power to a common power take off system. The study investigates the required capacity of the power take off (PTO system and the structural forces on a WEPTOS WEC prototype, intended for installation at Hanstholm (Denmark, based on large scale experimental tests using a highly realistic laboratory model of the complete device. The results hereof includes the rotational speed and transmitted torque (and hereby power to the PTO system using different PTO control strategies, the impact of fluctuations of the available mechanical power and the effect of limiting the PTO capacity on the annual energy production. Acquisition of structural forces includes mooring forces and structural bending moments in both production and extreme wave conditions, illustrating that the regulation of the angle in the A shape ensures that extreme forces on the structure can be kept in the same order of magnitude as in production conditions.

  3. Resonantly driven micromechanical energy converters; Resonante mikromechanische Energiewandler

    Energy Technology Data Exchange (ETDEWEB)

    Kuehne, Ingo

    2009-07-01

    This work focuses on the investigation of resonantly driven micromechanical energy harvesters. They are based on electromechanically coupled spring-mass-systems, converting mechanical vibrations into electrical energy by employing appropriate physical transduction mechanisms, such as the inductive, the piezoelectric and the capacitive principle. These three approaches are compared to each other, especially with respect to electrical energy density, scaling behaviour and microtechnological fabricability. Theoretical considerations lead to the decision to implement both a capacitive and a piezoelectric micromechanical energy harvester. The capacitive energy transducer essentially consists of a mass suspended by silicon springs. This mass simultaneously serves as a movable electrode. A fixed counter electrode completes the variable capacitor. In order to function properly, the parallel-plate capacitor needs to be biased electrically. In contrast to existing state of the art a new approach is introduced, employing two different electrode materials with a large difference in their work functions. A periodical mechanical excitation leads to a variation of the electrical energy content within the biased capacitor, thus inducing a current flow, which can be used for driving an external electrical load. For the piezoelectric energy harvester, the concept of a piezoelectric diaphragm with a mass attached to the surface was used and devices were implemented. A mechanical excitation leads to a periodic deflection of the diaphragm caused by the stiffly coupled inertial mass and, thus, to a changing mechanical stress distribution within the diaphragm. This, in turn, induces a periodic charge separation within the piezoelectric diaphragm. The energy generated in this way can be consumed by an external electrical load with appropriate impedance matching. Theoretical model descriptions are established for both types of energy harvesters based on systems of state space equations. On

  4. Hydroelectromechanical modelling of a piezoelectric wave energy converter

    Science.gov (United States)

    Renzi, E.

    2016-11-01

    We investigate the hydroelectromechanical-coupled dynamics of a piezoelectric wave energy converter. The converter is made of a flexible bimorph plate, clamped at its ends and forced to motion by incident ocean surface waves. The piezoceramic layers are connected in series and transform the elastic motion of the plate into useful electricity by means of the piezoelectric effect. By using a distributed-parameter analytical approach, we couple the linear piezoelectric constitutive equations for the plate with the potential-flow equations for the surface water waves. The resulting system of governing partial differential equations yields a new hydroelectromechanical dispersion relation, whose complex roots are determined with a numerical approach. The effect of the piezoelectric coupling in the hydroelastic domain generates a system of short- and long-crested weakly damped progressive waves travelling along the plate. We show that the short-crested flexural wave component gives a dominant contribution to the generated power. We determine the hydroelectromechanical resonant periods of the device, at which the power output is significant.

  5. Comparison of Foundation Systems for Wave Energy Converters Wavestar

    DEFF Research Database (Denmark)

    Vaitkunaite, Evelina; Ibsen, Lars Bo; Nielsen, Benjaminn Nordahl;

    2013-01-01

    In order to deliver cost competitive solutions, Wave Energy Converters (WEC) must be optimized in several fields, e.g. transportation, installation, structure, machinery etc. Large expenses lie on the superstructure support, i.e. the offshore foundation. Geotechnical analysis and optimization....... In such a solution horizontal wind and wave loads are dominant. Gravity based, pile and bucket foundations are universally applied solutions for the offshore structures. The suitability of these types for a WEC is analysed and commented. The foundations are designed to satisfy ultimate and serviceability limit state...... of six possible foundation solutions for WEC are presented in this article. The study is performed for WEC superstructure supported by two or four foundations. In the four-column system horizontal wind and wave loads are transformed as a pair of vertical forces, acting in tension and compression. When...

  6. Study of a Novel Oscillating Surge Wave Energy Converter: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Tom, Nathan M [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2017-08-01

    This study investigates the performance of an oscillating surge wave energy converter (OSWEC) that utilizes adjustable geometry as a means of controlling the hydrodynamic coefficients, a concept originally proposed by [1]. The body of the device consists of a bottom-hinged solid rectangular frame with five horizontal flaps spanning the interior of the frame. The flaps can rotate independently about their center of rotation within the frame like a large window shutter. Changing the orientation of the flaps alters the hydrodynamic coefficients and natural frequency of the device as well as the ability to shed or absorb structural loads accordingly. This ability may allow the device to operate in a wider range of sea states than other current wave energy converter designs. This paper presents and compares the results of numerical simulations and experimental testing of the OSWEC's response to regular waves with all five of the horizontal fin configurations sharing the same orientation of 0 degrees (fully closed interior) and 90 degrees (fully open). The numerical simulations were performed using WAMIT, which calculates hydrodynamic coefficients using a boundary element method code to solve the linear potential flow problem, and WEC-Sim, a MATLAB-based tool that simulates multibody devices in the time domain by solving the governing equations of motion. A 1:14 scale model of the device was built for experimental evaluation in an 8-m-long, 1-m wide wave tank, which supports a water depth of 0.7 m. The OSWEC motion in different wave conditions was measured with displacement sensors while nonlinear wave-structure interaction effects like slamming and overtopping were captured using a high-speed camera and used to understand differences between the simulation and experiments.

  7. Analysis of energy processes in pulse converters of AC electric power

    Directory of Open Access Journals (Sweden)

    Kadatsky A.F.

    2015-02-01

    Full Text Available The article presents the analysis of energy processes in switched-mode AC-AC converters of buck, boost and buck-boost types. The mathematical model of energy processes is obtained. The mathematical model is generalized to DC-DC and AC-AC converters, to three basic types of converters and considers possibility of autotransformer inclusion of an inductor. It is shown that the use of bi-directional switches allows both DC and AC conversion of electrical energy regardless of the load type and also supports recuperation of electrical energy back to the source. It is shown that the maximum value of instant power in a load circuit in AC—AC converters exceeds twice the rated value of load power in comparison with DC—DC converters. It is shown that the energy capacity of an inductor in AC—AC converters exceeds twice the energy capacity of DC—DC converters at the identical rated power of conversion. It is shown that the energy capacity of an inductor in converters of buck and boost types depends on the ratio of input and output voltage. Also, the energy capacity of an inductor in converters of buck-boost type does not depend on the ratio of input and output voltage. It is shown that the energy capacity of an inductor in converters of buck and boost types is lower than the energy capacity of an inductor in the converter of buck-boost type.

  8. Study of Power Converter Topologies with Energy Recovery and grid power flow control Part B: boost converter with energy storage

    CERN Document Server

    Rogelio, Garcia Retegui; Gustavo, Uicich; Mario, Benedetti; Gilles, Le Godec; Konstantinos, Papastergiou

    2015-01-01

    In the framework of a Transfer line (TT2) Consolidation Programme, a number of studies on Energy cycling have been commissioned. Part of this work involves the study of dierent power electronic system topologies for magnet energy recovery. In this report, the use of a boost front-end converter supplying DC link of a 4-quadrant magnet supply is analysed. The key objective of the study is to find control strategies that result in the control of the peak power required from the power network as well as to recover the magnet energy into capacitor banks with controlled voltage fluctuation. The study comprises the modelling of the system by means of the method of state averaging and the development of regulation strategies to energy management. The proposed control strategies can be divided in two groups: in the first group, the magnet current is used to define the reference for the control system, while in the second group this current is unknown and some strategies are devised to limit the power drawn from the el...

  9. Electron Thermionic Emission from Graphene and a Thermionic Energy Converter

    Science.gov (United States)

    Liang, Shi-Jun; Ang, L. K.

    2015-01-01

    In this paper, we propose a model to investigate the electron thermionic emission from single-layer graphene (ignoring the effects of the substrate) and to explore its application as the emitter of a thermionic energy converter (TIC). An analytical formula is derived, which is a function of the temperature, work function, and Fermi energy level. The formula is significantly different from the traditional Richardson-Dushman (RD) law for which it is independent of mass to account for the supply function of the electrons in the graphene behaving like massless fermion quasiparticles. By comparing with a recent experiment [K. Jiang et al., Nano Res. 7, 553 (2014)] measuring electron thermionic emission from suspended single-layer graphene, our model predicts that the intrinsic work function of single-layer graphene is about 4.514 eV with a Fermi energy level of 0.083 eV. For a given work function, a scaling of T3 is predicted, which is different from the traditional RD scaling of T2. If the work function of the graphene is lowered to 2.5-3 eV and the Fermi energy level is increased to 0.8-0.9 eV, it is possible to design a graphene-cathode-based TIC operating at around 900 K or lower, as compared with the metal-based cathode TIC (operating at about 1500 K). With a graphene-based cathode (work function=4.514 eV ) at 900 K and a metallic-based anode (work function=2.5 eV ) like LaB6 at 425 K, the efficiency of our proposed TIC is about 45%.

  10. Reliability-Based Structural Optimization of Wave Energy Converters

    Directory of Open Access Journals (Sweden)

    Simon Ambühl

    2014-12-01

    Full Text Available More and more wave energy converter (WEC concepts are reaching prototypelevel. Once the prototype level is reached, the next step in order to further decrease thelevelized cost of energy (LCOE is optimizing the overall system with a focus on structuraland maintenance (inspection costs, as well as on the harvested power from the waves.The target of a fully-developed WEC technology is not maximizing its power output,but minimizing the resulting LCOE. This paper presents a methodology to optimize thestructural design of WECs based on a reliability-based optimization problem and the intentto maximize the investor’s benefits by maximizing the difference between income (e.g., fromselling electricity and the expected expenses (e.g., structural building costs or failure costs.Furthermore, different development levels, like prototype or commercial devices, may havedifferent main objectives and will be located at different locations, as well as receive varioussubsidies. These points should be accounted for when performing structural optimizationsof WECs. An illustrative example on the gravity-based foundation of the Wavestar deviceis performed showing how structural design can be optimized taking target reliability levelsand different structural failure modes due to extreme loads into account.

  11. Modular DC-DC converter system for energy harvesting with EAPs

    Science.gov (United States)

    Eitzen, L.; Graf, C.; Maas, J.

    2013-04-01

    Energy harvesting with EAPs requires an energy-efficient power electronics providing a bidirectional energy transfer and operating voltages of up to several kilovolts. A possibility to achieve a high energy-efficiency for high voltage conversion is the use of a modular converter system consisting of several bidirectional converter modules, which are connected in series on the converter output side and in parallel at the input side. Since each converter stage provides only a part of the overall converter output voltage, the converter module output voltages can effectively be reduced by choosing the number of cascaded converter modules appropriately. This allows the use of standard semiconductor switches with superior electrical characteristics compared to high voltage semiconductors, enabling a high energy-efficiency and smaller passive components. Since EAP devices exhibit a mainly capacitive behavior and a limitation of the operating current is required for electrode protection, the utilized converter structure/topology has to be operated as a controllable current source on the lowest control level, which is achieved by operating the converter modules of the modular converter system with a subordinate closed-looped current control scheme. In order to avoid voltage unbalances among the single converter modules, a method for voltage balancing is presented. For validation, experimental results of a realized bidirectional flyback converter prototype are presented and discussed.

  12. Leaf Degradation, Macroinvertebrate Shredders & Energy Flow in Streams: A Laboratory-Based Exercise Examining Ecosystem Processes

    Science.gov (United States)

    Sparkes, Timothy C.; Mills, Colleen M.; Volesky, Lisa; Talkington, Jennifer; Brooke, Joanna

    2008-01-01

    A laboratory-based exercise that demonstrates mechanisms underlying leaf degradation in streams. Students examine the effects of "leaf conditioning" on the feeding behavior of invertebrate shredders. The exercise is completed in two sessions and can be adapted to both high school and college levels.

  13. HYDRODYNAMIC ANALYSIS OF SHORELINE OWC TYPE WAVE ENERGY CONVERTERS

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A numerical model to predict the hydrodynamic performance of a shoreline-mounted wave energy converter, normally referred to as Oscillating Water Column (OWC), was established. Based on the 3D boundary integral equation method, the 3D Green's function was utilized to describe the hydrodynamic flow around the device. Using geometrical data of a wave absorber device symmetrically placed in a channel with various barrier depths, the hydrodynamic efficiencies were calculated for regular waves. The results were the ncompared with analytical results published elsewhere Malmo[8] . And the comparison is shown to be good, thus validating the proposed numerical model. Furthermore, extensive experiments were also made in a wave tank with a 1:12 scale model of an OWC device of different geometrical configurations. The experimental measurements were compared with calculations using the newly developed numerical model. The comparison, which is also shown to be satisfactory, provides further support of the correctness and the accuracy of the numerical method presented in the paper.

  14. Coupling modeling and analysis of a wind energy converter

    Directory of Open Access Journals (Sweden)

    Jie-jie Li

    2016-06-01

    Full Text Available In this article, the numerical simulation of a 2.0-MW wind energy converter coupling is achieved by three-dimensional computer-aided design modeling technique and finite element method. The static performances and the buckling characteristics of the diaphragm coupling are investigated. The diaphragm coupling is divided into three substructures, namely, torque input end, the middle section, and the torque output end. Considering the assembly and contact conditions, the simulation analysis for stress responses of the diaphragm coupling is carried out. The buckling factor and buckling mode of the diaphragms are obtained, and the geometric parameters of the diaphragms are optimized according to their buckling characteristics. The relationship between the pretightening force of the bolts, which tighten the friction flange and the friction plate, and the sliding torque is given by an empirical formula. The reasonable ranges of the pretightening force and tighten torque of the bolts are recommended. The fatigue analysis of the diaphragms is completed, and the results show that the diaphragms are competent to the designed life of the diaphragm coupling.

  15. Structural Reliability of Plain Bearings for Wave Energy Converter Applications

    Directory of Open Access Journals (Sweden)

    Simon Ambühl

    2016-02-01

    Full Text Available The levelized cost of energy (LCOE from wave energy converters (WECs needs to be decreased in order to be able to become competitive with other renewable electricity sources. Probabilistic reliability methods can be used to optimize the structure of WECs. Optimization is often performed for critical structural components, like welded details, bolts or bearings. This paper considers reliability studies with a focus on plain bearings available from stock for the Wavestar device, which exists at the prototype level. The Wavestar device is a point absorber WEC. The plan is to mount a new power take-off (PTO system consisting of a discrete displacement cylinder (DDC, which will allow different hydraulic cycles to operate at constant pressure levels. This setup increases the conversion efficiency, as well as decouples the electricity production from the pressure variations within the hydraulic cycle when waves are passing. The new PTO system leads to different load characteristics at the floater itself compared to the actual setup where the turbine/generator is directly coupled to the fluctuating hydraulic pressure within the PTO system. This paper calculates the structural reliability of the different available plain bearings planned to be mounted at the new PTO system based on a probabilistic approach, and the paper gives suggestions for fulfilling the minimal target reliability levels. The considered failure mode in this paper is the brittle fatigue failure of plain bearings. The performed sensitivity analysis shows that parameters defining the initial crack size have a big impact on the resulting reliability of the plain bearing.

  16. Hydraulic evaluation of the Crest Wing wave energy converter

    Energy Technology Data Exchange (ETDEWEB)

    Kofoed, J.P.; Antonishen, M.

    2008-09-15

    The Crest Wing Wave Energy Converter is currently being developed by Henning Pilgaard, of WaveEnergyFyn, Denmark. It is meant to act like a carpet on the water, conforming to the shape of each wave and using that movement to generate power. The thought of making a WEC that acts like a carpet on top of the waves is not new; ongoing or past projects such as the Pelamis and Cockerel Raft were designed with this thought in mind. The real difference with the Crest Wing is that it has skirt drafts, that extend down into the water and create suction; this increases the effective mass of the WEC while minimizing the material use. Special attention was given to the design of the first and last floaters as they are meant to act as a smooth transition between wave and machine. Their purpose is to make sure that no air gets under the two middle floaters so that suction is not broken and the device continues to function well. In summary the Crest Wing functions and is able to produce power with a good overall efficiency. The configuration with relative reference PTO (Power Take Off) is superior. It has not been proven that the idea of mounting skirts on the floaters is leading to a better performance. Thus, the study leads to the conclusion that the idea of making a simple hinged raft type device is good, and it is likely that the construction cost for a device of this type can be kept down. However, the study also leaves the chance that some limited draft of skirts in combination with inlet/outlet devices, could prove beneficial. In case of further testing on this device, an effort should be made to design and construct a more easily and accurately controlled PTO model in the test setup. This could greatly improve the quality of the output of such tests. (ln)

  17. Structural Loads Analysis for Wave Energy Converters: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    van Rij, Jennifer A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Yu, Yi-Hsiang [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Guo, Yi [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2017-08-09

    This study explores and verifies the generalized body-modes method for evaluating the structural loads on a wave energy converter (WEC). Historically, WEC design methodologies have focused primarily on accurately evaluating hydrodynamic loads, while methodologies for evaluating structural loads have yet to be fully considered and incorporated into the WEC design process. As wave energy technologies continue to advance, however, it has become increasingly evident that an accurate evaluation of the structural loads will enable an optimized structural design, as well as the potential utilization of composites and flexible materials, and hence reduce WEC costs. Although there are many computational fluid dynamics, structural analyses and fluid-structure-interaction (FSI) codes available, the application of these codes is typically too computationally intensive to be practical in the early stages of the WEC design process. The generalized body-modes method, however, is a reduced order, linearized, frequency-domain FSI approach, performed in conjunction with the linear hydrodynamic analysis, with computation times that could realistically be incorporated into the WEC design process. The objective of this study is to verify the generalized body-modes approach in comparison to high-fidelity FSI simulations to accurately predict structural deflections and stress loads in a WEC. Two verification cases are considered, a free-floating barge and a fixed-bottom column. Details for both the generalized body-modes models and FSI models are first provided. Results for each of the models are then compared and discussed. Finally, based on the verification results obtained, future plans for incorporating the generalized body-modes method into the WEC simulation tool, WEC-Sim, and the overall WEC design process are discussed.

  18. A High Efficiency Boost Converter with MPPT Scheme for Low Voltage Thermoelectric Energy Harvesting

    Science.gov (United States)

    Guan, Mingjie; Wang, Kunpeng; Zhu, Qingyuan; Liao, Wei-Hsin

    2016-11-01

    Using thermoelectric elements to harvest energy from heat has been of great interest during the last decade. This paper presents a direct current-direct current (DC-DC) boost converter with a maximum power point tracking (MPPT) scheme for low input voltage thermoelectric energy harvesting applications. Zero current switch technique is applied in the proposed MPPT scheme. Theoretical analysis on the converter circuits is explored to derive the equations for parameters needed in the design of the boost converter. Simulations and experiments are carried out to verify the theoretical analysis and equations. A prototype of the designed converter is built using discrete components and a low-power microcontroller. The results show that the designed converter can achieve a high efficiency at low input voltage. The experimental efficiency of the designed converter is compared with a commercial converter solution. It is shown that the designed converter has a higher efficiency than the commercial solution in the considered voltage range.

  19. Class structure of electromechanical energy converter models with UML-diagrams application

    Directory of Open Access Journals (Sweden)

    V.Ye. Plyugin

    2014-04-01

    Full Text Available Theoretical results are presented, mathematical model formation by means of inheritance from a generalized class template is shown for a general electromechanical energy converter.

  20. Direct energy converter controllers for switched reluctance motor operation

    OpenAIRE

    Goodman, Andrew Simon

    2007-01-01

    There is increasing demand for simple motor drives offering high reliability and fault tolerance in applications such as the aerospace actuator industry, with the development of `more electric aircraft'. This thesis presents a motor drive employing a switched reluctance motor, the novel single sided matrix converter, and a novel double band hysteresis based control scheme for control of the converter, implemented using a field programmable gate array (FPGA). The single sided matrix co...

  1. High-Voltage DC-DC Converter Topology for PV Energy Utilization - Investigation and Implementation

    DEFF Research Database (Denmark)

    Sanjeevikumar, Padmanaban; Blaabjerg, Frede; Wheeler, Patrick

    2017-01-01

    This paper exploited the utilization of photovoltaic (PV) energy system with high-voltage (HV) output DC-DC converter. Classical boost converters are used for both renewable energy integration and HV applications, but limited by reducing output/efficiency in performance. Moreover, as parasitic...... elements suppress the power transfer ratio, converter needs to maximize the PV energy utilization. This investigation study focused to include additional parasitic elements (voltage-lift technique) to a standard DC-DC buck converter and to overcome all the above drawbacks to maximize the PV power...

  2. Model based feasibility study on bidirectional check valves in wave energy converters

    DEFF Research Database (Denmark)

    Hansen, Anders Hedegaard; Pedersen, Henrik C.; Andersen, Torben Ole

    2014-01-01

    Discrete fluid power force systems have been proposed as the primary stage for Wave Energy Converters (WEC’s) when converting ocean waves into electricity, this to improve the overall efficiency of wave energy devices. This paper presents a model based feasibility study of using bidirectional check...

  3. Results of an Experimental Study of the Langlee Wave Energy Converter

    DEFF Research Database (Denmark)

    Pecher, Arthur; Kofoed, Jens Peter; Espedal, J.

    2010-01-01

    This paper presents the results of the first experimental study of the Langlee wave energy converter (WEC), a semi-submerged oscillating wave surge converter. Its design extracts the energy from the surge motion of the waves through two pairs of working flaps, called water wings, which are placed...

  4. Mathematical modeling of a photovoltaic-laser energy converter for iodine laser radiation

    Science.gov (United States)

    Walker, Gilbert H.; Heinbockel, John H.

    1987-01-01

    Space-based laser power systems will require converters to change laser radiation into electricity. Vertical junction photovoltaic converters are promising devices for this use. A promising laser for the laser power station is the t-C4F9I laser which emits radiation at a wavelength of 1.315 microns. This paper describes the results of mathematical modeling of a photovoltaic-laser energy converter for use with this laser. The material for this photovoltaic converter is Ga(53)In(47)As which has a bandgap energy of 0.94 eV, slightly below the energy of the laser photons (0.943 eV). Results of a study optimizing the converter parameters are presented. Calculated efficiency for a 1000 vertical junction converter is 42.5 percent at a power density of 1 x 10 to the 3d power w/sq cm.

  5. Energy Evaluation for DC/DC Converters in DC-Based Wind Farms

    Energy Technology Data Exchange (ETDEWEB)

    Max, Lena

    2007-02-15

    In this thesis the suitability of three topologies for DC/DC converters in a DC wind farm grid is investigated from an energy efficiency and energy production cost point of view. The three selected topologies are the fullbridge converter, the single active bridge converter and the series parallel resonant converter. The losses are calculated for all three topologies as a function of the wind speed considering the losses in the semiconductor components and in the transformer. To obtain the average losses, the losses for each converter are integrated over the wind distribution for different average wind speeds. It is found that the resonant converter has the lowest losses of the three types for the DC wind farm application with power losses of about 2.0 - 2.5 % of the input power and the fullbridge converter has slightly higher losses with 2.3 - 3.5 % losses depending on the position in the wind turbine grid. The single active bridge converter has considerably higher losses than the other two topologies with 3.5 - 5.0 % losses. It is shown that the variable operating conditions create problems for all three converters, and as mentioned the single active bridge converter is most affected by the wide range of operation conditions. When comparing the resonant converter and the fullbridge converter, the fullbridge converter has a smaller transformer as well as lower peak current and peak voltage, but also a higher number of diode modules in the output bridge. Comparing the contribution to the energy production cost for the converters, the topology with the lowest contribution varies between the positions in the wind turbine grid. For some positions, the cost of the higher losses for the fullbridge converter are compensated by lower investment cost for the fullbridge converter compared to the resonant converter. Considering the resonant capacitor, the higher peak voltage and the variable frequency control for the resonant converter, the fullbridge converter is here found

  6. Porous silicon multitexture for photoelectric converter structures of solar energy

    Directory of Open Access Journals (Sweden)

    Yerokhov V. Yu.

    2009-06-01

    Full Text Available The possibility of creation of porous silicon’s multitexture, as material of structure of photoelectric converter (FEC is shown. The morphological elements of porous silicon are considered relative to different pore parameters. The integral coefficient of frontal surface reflection of FEC with using of columnar multitexture in the range from 400 nm up to 1150 nm decreased.

  7. Porous silicon multitexture for photoelectric converter structures of solar energy

    OpenAIRE

    Yerokhov V. Yu.; Druzinin A. O.

    2009-01-01

    The possibility of creation of porous silicon’s multitexture, as material of structure of photoelectric converter (FEC) is shown. The morphological elements of porous silicon are considered relative to different pore parameters. The integral coefficient of frontal surface reflection of FEC with using of columnar multitexture in the range from 400 nm up to 1150 nm decreased.

  8. Control and design of full-bridge three-level converter for renewable energy sources

    DEFF Research Database (Denmark)

    Yao, Zhilei; Xu, Jing; Guerrero, Josep M.

    2015-01-01

    Output voltage of renewable energy sources, such as fuel cell and PV cell, is often low and varies widely with load and environmental conditions. Therefore, the high step-up DC-DC converter is needed between renewable energy sources and the grid-connected inverter. However, voltage stress...... of rectifier diodes is high and filter is large in traditional voltage-source converters in a wide input-voltage range. In order to solve the aforementioned problems, a full-bridge (FB) three-level (TL) converter is proposed. It can operate at both two-level and three-level modes, so it is suitable for wide...... input-voltage range application. Compared with FB converter, voltage stress of rectifier diodes and the filter can be reduced. Operating principle and control strategy of the proposed converter are illustrated. Design guidelines and example are given. Simulation results of a 1-kW FB TL converter verify...

  9. Recombination in converters of β-radiation energy to electrical energy

    Science.gov (United States)

    Abanin, I. E.; Amelichev, V. V.; Bulyarskii, S. V.; Lakalin, A. V.

    2016-12-01

    β-to-electric energy converters based on high-ohmic silicon, as well as processes that provide a high conversion efficiency, have been studied. It has been shown that the conversion efficiency is related to recombination in the space-charge region of converters at low levels of injection. A technique for determining the parameters of recombination centers that is built on new conversion algorithms has been developed. These algorithms make it possible to change the monotonic (and exponential as a whole) current-voltage characteristic of the device to a singular curve and find the parameters of recombination centers. These parameters have been calculated in a wide temperature range. Regions in the temperature-forward bias coordinates have been revealed in which recombination fluxes are captured by a recombination center, which influences the saturation current of the current-voltage characteristic and the conversion efficiency.

  10. Discrimination of converted photons and neutral pions at high energies

    Institute of Scientific and Technical Information of China (English)

    XIAO Hong; WANG Jian; WANG Jian; WANG Xian-You; WANG Zheng; XU Ming; XU Wei-Wei; YANG Min; YAN Qi; CHEN Guo-Ming; TAO Jun-Quan; BIAN Jian-Guo; FAN Jia-Wei; LIANG Song; MENG Xiang-Wei; SHEN Yu-Qiao; TANG Zhi-Cheng

    2012-01-01

    In the LHC experiment,the H → γγ channel provides a clean final state with an effective mass peak that is reconstructed with great precision,despite the small branching ratio.As a consequence,the H → γγ channel is one of the most promising channels for the Higgs discovery in the very low mass region.In order to increase the sensitivity of the Higgs search,background rejection rate is very important,so γ/π0discrimination is one of the key points in the analysis.At least 40% of photons will convert with the experience of ATLAS and CMS.We constructed electromagnetic calorimeter (ECAL) in GEANT4 simulation,using 6variables which have different shapes between converted γ and π0,with the TMVA (Toolkit for Multivariate Data Analysis) to do the separation.With this method we can get 30% to 60% π0 rejection efficiency when keeping 90% converted γ efficiency,in the region of transverse momentum 15 GeV to 75 GeV,not only in MC sumulation but also in real data.

  11. A Modified C-Dump Converter for BLDC Machine Used in a Flywheel Energy Storage System

    Directory of Open Access Journals (Sweden)

    Bandaru Ramakrishna

    2014-10-01

    Full Text Available This paper presents a modified C-dump converter for brushless DC (BLDC machine used in the flywheel energy storage system. The converter can realize the energy bidirectional flowing and has the capability to recover the energy extracted from the turnoff phase of the BLDC machine. The principle of operation, modeling, and control strategy of the system has been investigated in the paper. Simulation and experimental results of the proposed system are also presented and discussed.

  12. Validation of a Tool for the Initial Dynamic Design of Mooring Systems for Large Floating Wave Energy Converters

    DEFF Research Database (Denmark)

    Thomsen, Jonas Bjerg; Ferri, Francesco; Kofoed, Jens Peter

    2017-01-01

    Mooring of floating wave energy converters is an important topic in renewable research since it highly influences the overall cost of the wave energy converter and thereby the cost of energy. In addition, several wave energy converter failures have been observed due to insufficient mooring system...

  13. Design of Power Converters for Renewable Energy Sources and Electric Vehicles Charging

    Directory of Open Access Journals (Sweden)

    Martin Tvrdon

    2013-01-01

    Full Text Available This paper describes the design and construction of new series of power converters equipped with liquid cooling system. This power series is created for project ENET – Energy Units for Utilization of non Traditional Energy Sources. First power converter is determined for stationary battery system use, the second one is used as an inverter/rectifier for a small solar plant system and the last power inverter is used as a fast charger for electric vehicles. Energy balance is performed for the fast charger converter, which is solved using numerical simulations of the system.

  14. Full wave dc-to-dc converter using energy storage transformers

    Science.gov (United States)

    Moore, E. T.; Wilson, T. G.

    1969-01-01

    Full wave dc-to-dc converter, for an ion thrustor, uses energy storage transformers to provide a method of dc-to-dc conversion and regulation. The converter has a high degree of physical simplicity, is lightweight and has high efficiency.

  15. Accelerated lifetime testing of energy storage capacitors used in particle accelerators power converters

    CERN Document Server

    AUTHOR|(SzGeCERN)679542; Genton, Charles-Mathieu

    2015-01-01

    Energy storage capacitors are used in large quantities in high power converters for particle accelerators. In this application capacitors see neither a DC nor an AC voltage but a combination of the two. The paper presents a new power converter explicitly designed to perform accelerated testing on these capacitors and the results of the tests.

  16. Power electronic converter systems for direct drive renewable energy applications

    DEFF Research Database (Denmark)

    Chen, Zhe

    2013-01-01

    This chapter presents power electronic conversion systems for wind and marine energy generation applications, in particular, direct drive generator energy conversion systems. Various topologies are presented and system design optimization and reliability are briefly discussed....

  17. Place and role of electrochemical energy converters in the energetics

    Directory of Open Access Journals (Sweden)

    Andrey Kurbatov

    2012-05-01

    Full Text Available The position of the electrochemical method of energy conversion of a chemical reaction in the overall energy production was considered. The effective ways and tendencies of its implementation were shown. The variants of electrochemical systems for the production, accumulation and storage of energy was also considered.

  18. Stakeholder requirements for commercially successful wave energy converter farms

    Energy Technology Data Exchange (ETDEWEB)

    Babarit, Aurélien; Bull, Diana; Dykes, Katherine; Malins, Robert; Nielsen, Kim; Costello, Ronan; Roberts, Jesse; Bittencourt Ferreira, Claudio; Kennedy, Ben; Weber, Jochem

    2017-12-01

    In this study, systems engineering techniques are applied to wave energy to identify and specify stakeholders' requirements for a commercially successful wave energy farm. The focus is on the continental scale utility market. Lifecycle stages and stakeholders are identified. Stakeholders' needs across the whole lifecycle of the wave energy farm are analyzed. A list of 33 stakeholder requirements are identified and specified. This list of requirements should serve as components of a technology performance level metric that could be used by investors and funding agencies to make informed decisions when allocating resources. It is hoped that the technology performance level metric will accelerate wave energy conversion technology convergence.

  19. Implementation of Control System for Hydrokinetic Energy Converter

    Directory of Open Access Journals (Sweden)

    Katarina Yuen

    2013-01-01

    Full Text Available At Uppsala University, a research group is investigating a system for converting the power in freely flowing water using a vertical-axis turbine directly connected to a permanent magnet generator. An experimental setup comprising a turbine, a generator, and a control system has been constructed and will be deployed in the Dalälven river in the town of Söderfors in Sweden. The design, construction, simulations, and laboratory tests of the control system are presented in this paper. The control system includes a startup sequence for the turbine and load control. These functions have performed satisfactorily in laboratory tests. Simulations of the system show that the power output is not maximized at the same tip-speed ratio as that which maximizes the turbine power capture.

  20. Energy-saving operation of a converter-fed synchronous machine

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, I.; Veszpremi, K. [Technical University of Budapest, Department of Electrical Machines and Drives, Budapest (Hungary)

    1997-12-31

    In the Converter-Fed Synchronous Machine (CFSM) there is no need for forced commutation the CL and CF converters operate with line commutation, the CM is commutated by the machine voltages. This drive is applied mainly for large power and high speed controlled drives. Considering the large power, the investigation of energy-saving operation is important. As in the DC and the induction motor drives the energy-saving operation is implemented by flux control. (orig.) 6 refs.

  1. Ac-dc Bus-interface Bi-directional Converters in Renewable Energy Systems

    OpenAIRE

    Dong, Dong

    2012-01-01

    This dissertation covers several issues related to the ac-dc bus-interface bi-directional converters in renewable energy systems. The dissertation explores a dc-electronic distribution system for residential and commercial applications with a focus on the design of an ac-dc bi-directional converter for such application. This converter is named as the â Energy Control Centerâ due to its unique role in the system. First, the impact of the unbalanced power from the ac grid, especially the ...

  2. A compact versatile matrix converter to integrate various energy resources to utility network

    DEFF Research Database (Denmark)

    Liu, Xiong; Loh, Poh Chiang; Wang, Peng;

    2011-01-01

    This paper proposes a multi-inputs versatile matrix converter (VMC) to integrate various energy resources and energy storages to a power grid. The VMC is developed based on a traditional indirect matrix converter (IMC) and a nineswitch converter. The six input terminals provide flexibility...... for the connection of two three-phase AC sources or one threephase AC and three DC sources, which make it possible to integrate both DC and AC renewable sources in a single gridtied power electronics interface. The control and modulation schemes are proposed to extract the commanded current from the input AC...

  3. Power Converters and Control of Renewable Energy Systems

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Teodorescu, Remus; Chen, Zhe;

    2004-01-01

    The global electrical energy consumption is steadily rising and therefore a continuous demand to increase the power generation capacity. A significant percentage of the required capacity increase can be based on renewable energy sources. Wind turbine technology, as the most cost effective renewable...... energy conversion system, will play an important part in our future energy supply. But other sources like microturbines, photovoltaics and fuel cell systems may also be serious contributor to the power supply. Characteristically, power electronics will be an efficient and important interface to the grid...... for the renewables and this paper will first briefly discuss three different alternative/renewable energy sources. Next, various configurations of small and medium power conversion topologies are presented including their control (mainly for PV-systems). Finally wind turbine configuration and their control...

  4. The Electrostatic Wind Energy Converter: electrical performance of a high voltage prototype

    NARCIS (Netherlands)

    Djairam, D.

    2008-01-01

    Wind energy is converted to electrical energy by letting the wind move charged particles against the direction of an electric field. The advantage of this type of conversion is that no rotational movement, which occurs in conventional wind turbines, is required. An electrostatic wind energy

  5. Analysis of DC/DC Converter Efficiency for Energy Storage System Based on Bidirectional Fuel Cells

    DEFF Research Database (Denmark)

    Pittini, Riccardo; Zhang, Zhe; Andersen, Michael A. E.

    2013-01-01

    Renewable energy sources are fluctuating depending on the availability of the energy source. For this reason, energy storage is becoming more important and bidirectional fuel cells represent an attractive technology. Fuel cells require highcurrent low-voltage dc-dc or dc-ac converters as power...

  6. Numerical Analysis of a Large Floating Wave Energy Converter with Adjustable Structural Geometry

    DEFF Research Database (Denmark)

    Ferri, Francesco; Pecher, Arthur Francois Serge; Kofoed, Jens Peter

    2015-01-01

    The current cost of energy (CoE) from wave energy converters (WECs) is still significantly higher than other renewable energy resources, thus the sector has not yet reached a competitive level. WECs have a relative small turnover compared to the high capital cost, which to a large extent is drive...

  7. Instrumentation for Monitoring around Marine Renewable Energy Converters: Workshop Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Polagye, B. L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Copping, A. E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Brown-Saracino, J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Suryan, R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Kramer, S. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Smith, C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2014-01-14

    To better understand the state of instrumentation and capabilities for monitoring around marine energy converters, the U.S. Department of Energy directed Pacific Northwest National Laboratory and the Northwest National Marine Renewable Energy Center at the University of Washington to convene an invitation-only workshop of experts from around the world to address instrumentation needs.

  8. A review of ocean energy converters, with an Australian focus

    Directory of Open Access Journals (Sweden)

    Chris Knight

    2014-08-01

    Full Text Available The requirement to move away from carbon based fossil fuels has led to a renewed interest in unconventional energy sources. Of interest in this article are ocean waves and current and tidal flows. This paper reviews the numerous options for ocean energy conversion systems that are currently available. A basic nomenclature for the variety of systems is utilized to classify the devices. A variety of issues including competing use, boating, fishing, commercial shipping and tourism are discussed with respect to impacts on and from ocean renewable energy.

  9. Life cycle assessment of the wave energy converter: Wave Dragon

    DEFF Research Database (Denmark)

    Hans Chr., Sørensen; Stefan, Naef; Stefan, Anderberg

    Any power production technology should be able to demonstrate that it's able to comply with current and future environmental regulation and that it demonstrates a considerable surplus in the energy balance being a part of the entire power system. This means that the energy used throughout all...... the lifecycle stages; from provision of materials over manufacturing of components and assembly, to deployment and use and eventually the disposal stage, is considerably less than the energy produced by the devise during its use/production stage....

  10. Cross-Regulation Assessment of DIDO Buck-Boost Converter for Renewable Energy Application

    Directory of Open Access Journals (Sweden)

    Deepak Elamalayil Soman

    2017-06-01

    Full Text Available When medium- or high-voltage power conversion is preferred for renewable energy sources, multilevel power converters have received much of the interest in this area as methods for enhancing the conversion efficiency and cost effectiveness. In such cases, multilevel, multi-input multi-output (MIMO configurations of DC-DC converters come to the scenario for integrating several sources together, especially considering the stringent regulatory needs and the requirement of multistage power conversion systems. Considering the above facts, a three-level dual input dual output (DIDO buck-boost converter, as the simplest form of MIMO converter, is proposed in this paper for DC-link voltage regulation. The capability of this converter for cross regulating the DC-link voltage is analyzed in detail to support a three-level neutral point clamped inverter-based grid connection in the future. The cross-regulation capability is examined under a new type of pulse delay control (PDC strategy and later compared with a three-level boost converter (TLBC. Compared to conventional boost converters, the high-voltage three-level buck boost converter (TLBBC with PDC exhibits a wide controllability range and cross regulation capability. These enhanced features are extremely important for better regulating variable output renewable energy sources such as solar, wind, wave, marine current, etc. The simulation and experimental results are provided to validate the claim.

  11. Neural rotational speed control for wave energy converters

    Science.gov (United States)

    Amundarain, M.; Alberdi, M.; Garrido, A. J.; Garrido, I.

    2011-02-01

    Among the benefits arising from an increasing use of renewable energy are: enhanced security of energy supply, stimulation of economic growth, job creation and protection of the environment. In this context, this study analyses the performance of an oscillating water column device for wave energy conversion in function of the stalling behaviour in Wells turbines, one of the most widely used turbines in wave energy plants. For this purpose, a model of neural rotational speed control system is presented, simulated and implemented. This scheme is employed to appropriately adapt the speed of the doubly-fed induction generator coupled to the turbine according to the pressure drop entry, so as to avoid the undesired stalling behaviour. It is demonstrated that the proposed neural rotational speed control design adequately matches the desired relationship between the slip of the doubly-fed induction generator and the pressure drop input, improving the power generated by the turbine generator module.

  12. Energy-Efficient Capacitance-to-Digital Converters for Low-Energy Sensor Nodes

    KAUST Repository

    Omran, Hesham

    2015-11-01

    Energy efficiency is a key requirement for wireless sensor nodes, biomedical implants, and wearable devices. The energy consumption of the sensor node needs to be minimized to avoid battery replacement, or even better, to enable the device to survive on energy harvested from the ambient. Capacitive sensors do not consume static power; thus, they are attractive from an energy efficiency perspective. In addition, they can be employed in a wide range of sensing applications. However, the sensor readout circuit–i.e., the capacitance-to-digital converter (CDC)–can be the dominant source of energy consumption in the system. Thus, the development of energy-efficient CDCs is crucial to minimizing the energy consumption of capacitive sensor nodes. In the first part of this dissertation, we propose several energy-efficient CDC architectures for low-energy sensor nodes. First, we propose a digitally-controlled coarsefine multislope CDC that employs both current and frequency scaling to achieve significant improvement in energy efficiency. Second, we analyze the limitations of successive approximation (SAR) CDC, and we address these limitations by proposing a robust parasitic-insensitive opamp-based SAR CDC. Third, we propose an inverter-based SAR CDC that achieves an energy efficiency figure-of-merit (FoM) of 31fJ/Step, which is the best energy efficiency FoM reported to date. Fourth, we propose a differential SAR CDC with quasi-dynamic operation to maintain excellent energy efficiency for a scalable sample rate. In the second part of this dissertation, we study the matching properties of small integrated capacitors, which are an integral component of energy-efficient CDCs. Despite conventional wisdom, we experimentally illustrate that the mismatch of small capacitors can be directly measured, and we report mismatch measurements for subfemtofarad integrated capacitors. We also correct the common misconception that lateral capacitors match better than vertical capacitors

  13. From Animal Waste to Energy; A Study of Methane Gas converted to Energy.

    Science.gov (United States)

    Weiss, S.

    2016-12-01

    Does animal waste produce enough harvestable energy to power a household, and if so, what animal's waste can produce the most methane that is usable. What can we power using this methane and how can we power these appliances within an average household using the produced methane from animal waste. The waste product from animals is readily available all over the world, including third world countries. Using animal waste to produce green energy would allow low cost energy sources and give independence from fossil fuels. But which animal produces the most methane and how hard is it to harvest? Before starting this experiment I knew that some cow farms in the northern part of the Central California basin were using some of the methane from the waste to power their machinery as a safer, cheaper and greener source through the harnessed methane gas in a digester. The fermentation process would occur in the digester producing methane gasses as a side product. Methane that is collected can later be burned for energy. I have done a lot of research on this experiment and found that many different farm and ranch animals produce methane, but it was unclear which produced the most. I decided to focus my study on the waste from cows, horses, pig and dogs to try to find the most efficient and strongest source of methane from animal waste. I produced an affordable methane digester from plastic containers with a valve to attach a hose. By putting in the waste product and letting it ferment with water, I was able to produce and capture methane, then measure the amount with a Gaslab meter. By showing that it is possible to create energy with this simple digester, it could reduce pollution and make green energy easily available to communities all over the world. Eventually this could result into our sewer systems converting waste to energy, producing an energy source right in your home.

  14. Simplified Design Procedures for Moorings of Wave-Energy Converters

    DEFF Research Database (Denmark)

    Bergdahl, Lars; Kofoed, Jens Peter

    The goal of the report is that the reader shall be able to self-dependently make a first, preliminary analysis of wave-induced horizontal loads, motions and mooring forces for a moored floating wave energy device. Necessary prerequisites to attain that goal are the understanding of the physical...

  15. Design Specifications for the Hanstholm WEPTOS Wave Energy Converter

    DEFF Research Database (Denmark)

    Pecher, Arthur; Kofoed, Jens Peter; Larsen, Tommy

    2012-01-01

    -moored and floating structure absorbs the energy of the waves through a multitude of rotors. The shape of the rotors is based on the renowned Salter’s Duck. On each leg, the rotors pivot around a common axle, through which the rotors transfer the absorbed power to a common power take off system. The study...

  16. Collecting of new data on existing wind energy converters

    Science.gov (United States)

    Jensen, S. A.; Bjerregaard, E. T. D.; Paulsen, U. S.

    Measurements on a 55 kW VESTAS wind turbine were carried out during a period of approximately 2 months. The wind turbine is erected at a farm, and the produced energy is used for central heating and in cooling and drying systems at the farm. The energy production of the wind turbine is calculated as a function of the annual mean wind speed, and it is assumed that the wind speed frequency distribution is a Rayleigh distribution. The energy production during a period of 46 days from January the 20th to March the 7th 1983 was 20,665 kWh, and the total energy consumption by the owner in the same period was 12,983 kWh. The mean wind speed at hub height during the same period was 7.6 m/s. Approximately 8975 kWh or 69 per cent of the consumption was delivered directly from the wind turbine, and 11,690 kWh produced by the wind turbine was sold to the power supply company.

  17. Energy Factor and Mathematical Modeling for Power DC/DC Converters

    Institute of Scientific and Technical Information of China (English)

    Fang Lin LUO; Hong YE

    2004-01-01

    Mathematical modelling for power DC/DC converters is a historical problem accompanying DC/DC conversion technology since 1940's. The traditional mathematical modelling is not available for complex structure converters since the differential equation order increases very high. We have to search other way to establish mathematical modelling for power DC/DC converters. We have theoretically defined a new concept - Energy Factor (EF) in this paper and researched the relations between EF and the mathematical modelling for power DC/DC converters. EF is a new concept in power DC/DC conversion technology, which thoroughly differs from the traditional concepts such as power factor (PF), power transfer efficiency (η), total harmonic distortion (THD) and ripple factor (RF). EF and the subsequential EFv (and EFvD ) can illustrate the system stability, reference response and interference recovery. This investigation is very helpful for system design and DC/DC converters characteristics foreseeing. Two DC/DC converters: Buck converter and Super-Lift Luo-Converter as the samples are analysed in this paper to demonstrate the applications of EF, EFv (and EFvD), PE,SE, VE (and VED ), time constant τ and damping time constant τd .

  18. Two Level Versus Matrix Converters Performance in Wind Energy Conversion Systems Employing DFIG

    Science.gov (United States)

    Reddy, Gongati Pandu Ranga; Kumar, M. Vijaya

    2017-05-01

    Wind power capacity has received enormous growth during past decades. With substantial development of wind power, it is expected to provide a fifth of world's electricity by the end of 2030. In wind energy conversion system, the power electronic converters play an important role. This paper presents the two level and matrix converters performance in wind energy conversion system employing Doubly Fed Induction Generator (DFIG). The DFIG is a wound rotor induction generator. Because of the advantages of the DFIG over other generators it is being used for most of the wind applications. This paper also discusses control of converters using the space vector pulse width modulation technique. The MATLAB/SIMULINK ® software is used to study the performance of the converters.

  19. Design and characterization of a fractal-inspired multi-frequency piezoelectric energy converter

    Directory of Open Access Journals (Sweden)

    Davide Castagnetti

    2013-01-01

    Full Text Available A promising harvesting technique, in terms of simplicity and efficiency, is the conversion of ambient kinetic energy through piezoelectric materials. This work aims to design and investigate a piezoelectric converter conform to a fractal-inspired, multi-frequency structure previously presented by the author. A physical prototype of the converter is built and experimentally examined, up to 120 Hz, in terms of modal response and power output. Three eigenfrequencies are registered and the power output is particularly good at the fundamental eigenfrequency. Also the effect of the resistive load applied to the converter is investigated.

  20. Inclusion of Structural Flexibility in Design Load Analysis for Wave Energy Converters: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Yi [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Yu, Yi-Hsiang [National Renewable Energy Laboratory (NREL), Golden, CO (United States); van Rij, Jennifer A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Tom, Nathan M [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2017-08-14

    Hydroelastic interactions, caused by ocean wave loading on wave energy devices with deformable structures, are studied in the time domain. A midfidelity, hybrid modeling approach of rigid-body and flexible-body dynamics is developed and implemented in an open-source simulation tool for wave energy converters (WEC-Sim) to simulate the dynamic responses of wave energy converter component structural deformations under wave loading. A generalized coordinate system, including degrees of freedom associated with rigid bodies, structural modes, and constraints connecting multiple bodies, is utilized. A simplified method of calculating stress loads and sectional bending moments is implemented, with the purpose of sizing and designing wave energy converters. Results calculated using the method presented are verified with those of high-fidelity fluid-structure interaction simulations, as well as low-fidelity, frequency-domain, boundary element method analysis.

  1. An Experimental Study on A Trapezoidal Pendulum Wave Energy Converter in Regular Waves

    Institute of Scientific and Technical Information of China (English)

    王冬姣; 邱守强; 叶家玮

    2015-01-01

    Experimental studies were conducted on a trapezoidal pendulum wave energy converter in regular waves. To obtain the incident wave height, the analytical method (AM) was used to separate the incident and reflected waves propagating in a wave flume by analysing wave records measured at two locations. The response amplitude operator (RAO), primary conversion efficiency and the total conversion efficiency of the wave energy converter were studied; furthermore, the power take-off damping coefficients corresponding to the load resistances in the experiment were also obtained. The findings demonstrate that the natural period for a pendulum wave energy converter is relatively large. A lower load resistance gives rise to a larger damping coefficient. The model shows relatively higher wave energy conversion efficiency in the range of 1.0-1.2 s for the incident wave period. The maximum primary conversion efficiency achieved was 55.5%, and the maximum overall conversion efficiency was 39.4%.

  2. Increasing durability and lowering the overall cost of wave energy converters using Ultra High Performance Concrete

    DEFF Research Database (Denmark)

    Jepsen, Michael S.; Damkilde, Lars; Hansen, Niels A.

    2013-01-01

    Lowering the overall cost of wave energy converters is a necessity for creating a feasible solution to renewable energy. The design of wave energy converters is in general based on traditional steel design methods. In the design of steel structures subjected to significant dynamical loading...... and a harsh environment issues such fatigue resistance and durability are of major concern. The welded joints in steel structures significantly reduce the fatigue resistance and give a low utilization ratio of the steel material. Furthermore is coating of all exposed steel surfaces a necessity to secure...... as primary material in the design of wave energy converters is a feasible and promising solution, which reduce the overall cost of the structure significantly. This will be illustrated by means of a feasibility study carried out on the Wavestar project, where special attention is pointed at the arm and float...

  3. Analysis of Discharge Spark Energy in Buck Converter of a Continuous Mode of Inductive Current

    Institute of Scientific and Technical Information of China (English)

    CUI Bao-chun; CHENG Hong; WANG Cong; LU Huan-yu; SHI Yun

    2006-01-01

    The basic idea of intrinsically safe circuit and the discharge spark in the Buck converter in the explosive atmospheres were introduced. The Buck converter is the main topological structure of the switch type of intrinsically safe circuit, which has two working modes: continuous inductive current (CCM - continuous conduction mode) and discrete inductance current (DCM - discontinuous conduction mode). The operating state of the continuous inductive current mode is analyzed in detail and the energy of discharge spark in various operating modes is discussed. The total energy will decrease with the increase of switch frequency, in a switching cycle; the discharge spark energy has a maximum and a minimum value. Therefore, the Buck converter has smaller discharge spark energy than the linear power circuit and the switch type of intrinsically safe circuit can enhance the output power and the conversion efficiency of the intrinsically safe power.

  4. Calculating the rate of exothermic energy release for catalytic converter efficiency monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Hepburn, J.S.; Meitzler, A.H. [Ford Motor Co., Dearborn, MI (United States)

    1995-12-31

    This paper reports on the development of a new methodology for OBD-II catalyst efficiency monitoring. Temperature measurements taken from the center of the catalyst substrate or near the exterior surface of the catalyst brick were used in conjunction with macroscopic energy balances to calculate the instantaneous rate of exothermic energy generation within the catalyst. The total calculated rate of exothermic energy release over the FTP test cycle was within 10% of the actual or theoretical value and provided a good indicator of catalyst light-off for a variety of aged catalytic converters. Normalization of the rate of exothermic energy release in the front section of the converter by the mass flow rate of air inducted through the engine was found to provide a simple yet practical means of monitoring the converter under both FTP and varying types of road driving.

  5. Discrete Displacement Hydraulic Power Take-Off System for the Wavestar Wave Energy Converter

    DEFF Research Database (Denmark)

    Hansen, Rico Hjerm; Kramer, Morten; Vidal, Enrique

    2013-01-01

    The Wavestar Wave Energy Converter (WEC) is a multiple absorber concept, consisting of 20 hemisphere shaped floats attached to a single platform. The heart of the Wavestar WEC is the Power Take-Off (PTO) system, converting the wave induced motion of the floats into a steady power output to the grid....... In the present work, a PTO based on a novel discrete displacement fluid power technology is explored for the Wavestar WEC. Absorption of power from the floats is performed by hydraulic cylinders, supplying power to a common fixed pressure system with accumulators for energy smoothing. The stored pressure energy...

  6. Revenue Optimization for the Ocean Grazer Wave Energy Converter through Storage Utilization

    NARCIS (Netherlands)

    Dijkstra, H.T.; Barradas Berglind, J.J.; Meijer, H.; van Rooij, Marijn; Prins, W.A.; Vakis, A. I.; Jayawardhana, B.

    2016-01-01

    Increased penetration of renewable energy generation motivates a change of paradigm in the way power systems are structured and operated, as advocated by the smart grid concept. Accordingly, in this paper we investigate the lossless storage capabilities of the Ocean Grazer wave energy converter (WEC

  7. The research of multilevel transistor inverter for converting energy of solar panels

    Science.gov (United States)

    Taissariyeva, K. N.; Issembergenov, N. T.

    2015-09-01

    This article considers multilevel transistor inverter for converting energy of solar panels into electroenergy. The output of multilevel transistor inverter produces the voltage of almost sinusoidal form. The primary objective of this inverter is to transform solar energy into electroenergy of industrial frequency. The analysis of received output curves of voltage for sinusoidality has been conducted.

  8. Muon detection studied by pulse-height energy analysis: Novel converter arrangements

    Energy Technology Data Exchange (ETDEWEB)

    Holmlid, Leif, E-mail: holmlid@chem.gu.se [Atmospheric Science, Department of Chemistry and Molecular Biology, University of Gothenburg, SE-412 96 Göteborg (Sweden); Olafsson, Sveinn [Faculty of Physical Sciences, University of Iceland, Reykjavik (Iceland)

    2015-08-15

    Muons are conventionally measured by a plastic scintillator–photomultiplier detector. Muons from processes in ultra-dense hydrogen H(0) are detected here by a novel type of converter in front of a photomultiplier. The muon detection yield can be increased relative to that observed with a plastic scintillator by at least a factor of 100, using a converter of metal, semiconductor (Ge), or glass for interaction with the muons penetrating through the metal housing of the detector. This detection process is due to transient formation of excited nuclei by the well-known process of muon capture, giving beta decay. The main experimental results shown here are in the form of beta electron energy spectra detected directly by the photomultiplier. Events which give a high-energy tail in the energy spectra are probably due to gamma photons from the muons. Sharp and intense x-ray peaks from a muonic aluminium converter or housing material are observed. The detection conversion in glass and Ge converters has a time constant of the order of many minutes to reach the final conversion level, while the process in metal converters is stabilized faster. The time constants are not due to lifetimes of the excited nuclei or neutrons but are due to internal charging in the insulating converter material. Interaction of this charging with the high voltage in the photomultiplier is observed.

  9. Muon detection studied by pulse-height energy analysis: Novel converter arrangements

    Science.gov (United States)

    Holmlid, Leif; Olafsson, Sveinn

    2015-08-01

    Muons are conventionally measured by a plastic scintillator-photomultiplier detector. Muons from processes in ultra-dense hydrogen H(0) are detected here by a novel type of converter in front of a photomultiplier. The muon detection yield can be increased relative to that observed with a plastic scintillator by at least a factor of 100, using a converter of metal, semiconductor (Ge), or glass for interaction with the muons penetrating through the metal housing of the detector. This detection process is due to transient formation of excited nuclei by the well-known process of muon capture, giving beta decay. The main experimental results shown here are in the form of beta electron energy spectra detected directly by the photomultiplier. Events which give a high-energy tail in the energy spectra are probably due to gamma photons from the muons. Sharp and intense x-ray peaks from a muonic aluminium converter or housing material are observed. The detection conversion in glass and Ge converters has a time constant of the order of many minutes to reach the final conversion level, while the process in metal converters is stabilized faster. The time constants are not due to lifetimes of the excited nuclei or neutrons but are due to internal charging in the insulating converter material. Interaction of this charging with the high voltage in the photomultiplier is observed.

  10. Studi Komparasi Fungsi Keanggotaan Fuzzy sebagai Kontroler Bidirectional DC-DC Converter pada Sistem Penyimpan Energi

    Directory of Open Access Journals (Sweden)

    Eka Prasetyono

    2015-09-01

    Full Text Available Bidirectional DC-DC converter is needed in the energy storage system. The converter topology used in this paper was a non-isolated bidirectional DC-DC buck-boost converter. This converter worked in two ways, which the charging mode stored energy into battery when load current was less than nominal main DC current (set point and discharging mode transferred energy from battery to the load when its current exceeded set point value. Both of these modes worked automatically according to the load current. The charging and discharging currents were controlled by fuzzy logic controller which was implemented on microcontroller ARM Cortex-M4F STM32F407VG. This paper compares two types of fuzzy membership function (triangular and sigmoid in controlling bidirectional DC-DC converter. The results showed that fuzzy logic controller with triangle membership function and sigmoid as control bidirectional DC-DC converter had no significant different response, both had an average error for charging and discharging process under 4% with ripple current on the main DC bus around 0.5%. The computing time of program for fuzzy logic controller with triangular membership functions had 19.01% faster than sigmoid, and fuzzy logic computation time on a microcontroller with hardware floating point was 60% faster than software floating point.

  11. Cascaded H-Bridge with Bidirectional Boost Converters for Energy Storage

    DEFF Research Database (Denmark)

    Trintis, Ionut; Munk-Nielsen, Stig; Teodorescu, Remus

    2011-01-01

    This paper presents the design and control of a cascaded H-bridge converter for energy storage with bidirectional boost converter as charge/discharge unit. The disadvantage of the second harmonic on the main energy storage unit as well as its voltage variation with the state of charge is solved...... by this structure. The independent phase grid control is proposed for this topology. This strategy is able to control the average dc-link voltage for each phase independently and to balance the cells capacitors voltages. The balance of the energy storage units is achieved by controlling independently each cell...... charge/discharge current, together with the capacitors voltage control and balancing. Converter cell loss distribution and total loss over a wide battery voltage variation is calculated for charge/discharge operation modes for a 4.16 kV grid coupling point and 5 MW rated power....

  12. Model predictive control of bidirectional isolated DC-DC converter for energy conversion system

    Science.gov (United States)

    Akter, Parvez; Uddin, Muslem; Mekhilef, Saad; Tan, Nadia Mei Lin; Akagi, Hirofumi

    2015-08-01

    Model predictive control (MPC) is a powerful and emerging control algorithm in the field of power converters and energy conversion systems. This paper proposes a model predictive algorithm to control the power flow between the high-voltage and low-voltage DC buses of a bidirectional isolated full-bridge DC-DC converter. The predictive control algorithm utilises the discrete nature of the power converters and predicts the future nature of the system, which are compared with the references to calculate the cost function. The switching state that minimises the cost function is selected for firing the converter in the next sampling time period. The proposed MPC bidirectional DC-DC converter is simulated with MATLAB/Simulink and further verified with a 2.5 kW experimental configuration. Both the simulation and experimental results confirm that the proposed MPC algorithm of the DC-DC converter reduces reactive power by avoiding the phase shift between primary and secondary sides of the high-frequency transformer and allow power transfer with unity power factor. Finally, an efficiency comparison is performed between the MPC and dual-phase-shift-based pulse-width modulation controlled DC-DC converter which ensures the effectiveness of the MPC controller.

  13. A mechanical energy harvested magnetorheological damper with linear-rotary motion converter

    Science.gov (United States)

    Chu, Ki Sum; Zou, Li; Liao, Wei-Hsin

    2016-04-01

    Magnetorheological (MR) dampers are promising to substitute traditional oil dampers because of adaptive properties of MR fluids. During vibration, significant energy is wasted due to the energy dissipation in the damper. Meanwhile, for conventional MR damping systems, extra power supply is needed. In this paper, a new energy harvester is designed in an MR damper that integrates controllable damping and energy harvesting functions into one device. The energy harvesting part of this MR damper has a unique mechanism converting linear motion to rotary motion that would be more stable and cost effective when compared to other mechanical transmissions. A Maxon motor is used as a power generator to convert the mechanical energy into electrical energy to supply power for the MR damping system. Compared to conventional approaches, there are several advantages in such an integrated device, including weight reduction, ease in installation with less maintenance. A mechanical energy harvested MR damper with linear-rotary motion converter and motion rectifier is designed, fabricated, and tested. Experimental studies on controllable damping force and harvested energy are performed with different transmissions. This energy harvesting MR damper would be suitable to vehicle suspensions, civil structures, and smart prostheses.

  14. Investigations of DC power supplies with optoelectronic transducers and RF energy converters

    Science.gov (United States)

    Guzowski, B.; Gozdur, R.; Bernacki, L.; Lakomski, M.

    2016-04-01

    Fiber Distribution Cabinets (FDC) monitoring systems are increasingly popular. However it is difficult to realize such system in passive FDC, due to lack of source of power supply. In this paper investigation of four different DC power supplies with optoelectronic transducers is described. Two converters: photovoltaic power converter and PIN photodiode can convert the light transmitted through the optical fiber to electric energy. Solar cell and antenna RF-PCB are also tested. Results presented in this paper clearly demonstrate that it is possible to build monitoring system in passive FDC. During the tests maximum obtained output power was 11 mW. However all converters provided enough power to excite 32-bit microcontroller with ARM-cores and digital thermometer.

  15. Autonomous Control of Interlinking Converter With Energy Storage in Hybrid AC–DC Microgrid

    DEFF Research Database (Denmark)

    Loh, Poh Chiang; Li, Ding; Chai, Yi Kang

    2013-01-01

    The coexistence of ac and dc subgrids in a hybrid microgrid is likely given that modern distributed sources can either be ac or dc. Linking these subgrids is a power converter, whose topology should preferably be not too unconventional. This is to avoid unnecessary compromises to reliability......, simplicity, and industry relevance of the converter. The desired operating features of the hybrid microgrid can then be added through this interlinking converter. To demonstrate, an appropriate control scheme is now developed for controlling the interlinking converter. The objective is to keep the hybrid...... microgrid in autonomous operation with active power proportionally shared among its distributed sources. Power sharing here should depend only on the source ratings and not their placements within the hybrid microgrid. The proposed scheme can also be extended to include energy storage within...

  16. Converting chemical energy into electricity through a functionally cooperating device with diving-surfacing cycles.

    Science.gov (United States)

    Song, Mengmeng; Cheng, Mengjiao; Ju, Guannan; Zhang, Yajun; Shi, Feng

    2014-11-05

    A smart device that can dive or surface in aqueous medium has been developed by combining a pH-responsive surface with acid-responsive magnesium. The diving-surfacing cycles can be used to convert chemical energy into electricity. During the diving-surfacing motion, the smart device cuts magnetic flux lines and produces a current, demonstrating that motional energy can be realized by consuming chemical energy of magnesium, thus producing electricity.

  17. Initial Sea Trails of the DEXA D05 Wave Energy Converter

    DEFF Research Database (Denmark)

    Lavelle, John; Kofoed, Jens Peter

    This report presents an analysis of sensors data leading to an initial assessment of the power performance from sea trails of the DEXA D05 Wave Energy Converter (WEC). The sea trails where performed approx. 1 nautical mile offshore from Hanstholm, Denmark during 2011. The converter was 1:5 scale....... The DEXA D05 WEC was built, deployed and operated by the client DEXAWAVE ApS and the analysis of the sensor data, given here, has been carried out by John Lavelle under supervision by Jens Peter Kofoed in the Wave Energy Research Group at the department of Civil Engineering, Aalborg University (AAU)....

  18. Modelling of the Overtopping Flow on the Wave Dragon Wave Energy Converter

    DEFF Research Database (Denmark)

    Parmeggiani, Stefano; Pecher, Arthur; Kofoed, Jens Peter

    2010-01-01

    The Wave Dragon is a floating slack-moored Wave Energy Converter of the overtopping type, which is facing now the last phase of development before the commercial exploitation: the deployment of a full-scale demonstrator. In this phase a modelling tool allowing for accurate predictions of the perf......The Wave Dragon is a floating slack-moored Wave Energy Converter of the overtopping type, which is facing now the last phase of development before the commercial exploitation: the deployment of a full-scale demonstrator. In this phase a modelling tool allowing for accurate predictions...

  19. Fatigue and Serviceability Limit State Model Basis for Assessment of Offshore Wind Energy Converters

    DEFF Research Database (Denmark)

    Thons, S.; Faber, M. H.; Rücker, W.

    2012-01-01

    This paper develops the models for the structural performance of the loading and probabilistic characterization for the fatigue and the serviceability limit states for the support structure of offshore wind energy converters. These models and a sensitivity study are part of a risk based assessment...... al. ("Ultimate Limit State Model Basis for Assessment of Offshore Wind Energy Con-verters," ASME J. Offshore Mech. Arct. Eng.), the model basis for the assessment is completed. The process of establishing and analyzing such a model basis contributes to a detailed understanding of the deterministic...

  20. Vertical Distribution of Wave Overtopping for Design of Multi Level Overtopping Based Wave Energy Converters

    DEFF Research Database (Denmark)

    Kofoed, Jens Peter

    2007-01-01

    This paper presents an expression describing the vertical distribution of overtopping, the experimental work leading to this, as well as the use of the expression for numerical optimization of the geometrical layout of the multi level overtopping based wave energy converter Seawave Slot-cone Gene......This paper presents an expression describing the vertical distribution of overtopping, the experimental work leading to this, as well as the use of the expression for numerical optimization of the geometrical layout of the multi level overtopping based wave energy converter Seawave Slot...

  1. Underwater Noise from a Wave Energy Converter Is Unlikely to Affect Marine Mammals.

    Science.gov (United States)

    Tougaard, Jakob

    2015-01-01

    Underwater noise was recorded from the Wavestar wave energy converter; a full-scale hydraulic point absorber, placed on a jack-up rig on the Danish North Sea coast. Noise was recorded 25 m from the converter with an autonomous recording unit (10 Hz to 20 kHz bandwidth). Median sound pressure levels (Leq) in third-octave bands during operation of the converter were 106-109 dB re. 1 μPa in the range 125-250 Hz, 1-2 dB above ambient noise levels (statistically significant). Outside the range 125-250 Hz the noise from the converter was undetectable above the ambient noise. During start and stop of the converter a more powerful tone at 150 Hz (sound pressure level (Leq) 121-125 dB re 1 μPa) was easily detectable. This tone likely originated from the hydraulic pump which was used to lower the absorbers into the water and lift them out of the water at shutdown. Noise levels from the operating wave converter were so low that they would barely be audible to marine mammals and the likelihood of negative impact from the noise appears minimal. A likely explanation for the low noise emissions is the construction of the converter where all moving parts, except for the absorbers themselves, are placed above water on a jack-up rig. The results may thus not be directly transferable to other wave converter designs but do demonstrate that it is possible to harness wave energy without noise pollution to the marine environment.

  2. Underwater Noise from a Wave Energy Converter Is Unlikely to Affect Marine Mammals.

    Directory of Open Access Journals (Sweden)

    Jakob Tougaard

    Full Text Available Underwater noise was recorded from the Wavestar wave energy converter; a full-scale hydraulic point absorber, placed on a jack-up rig on the Danish North Sea coast. Noise was recorded 25 m from the converter with an autonomous recording unit (10 Hz to 20 kHz bandwidth. Median sound pressure levels (Leq in third-octave bands during operation of the converter were 106-109 dB re. 1 μPa in the range 125-250 Hz, 1-2 dB above ambient noise levels (statistically significant. Outside the range 125-250 Hz the noise from the converter was undetectable above the ambient noise. During start and stop of the converter a more powerful tone at 150 Hz (sound pressure level (Leq 121-125 dB re 1 μPa was easily detectable. This tone likely originated from the hydraulic pump which was used to lower the absorbers into the water and lift them out of the water at shutdown. Noise levels from the operating wave converter were so low that they would barely be audible to marine mammals and the likelihood of negative impact from the noise appears minimal. A likely explanation for the low noise emissions is the construction of the converter where all moving parts, except for the absorbers themselves, are placed above water on a jack-up rig. The results may thus not be directly transferable to other wave converter designs but do demonstrate that it is possible to harness wave energy without noise pollution to the marine environment.

  3. Design of Energy Storage Reactors for Dc-To-Dc Converters. Ph.D. Thesis

    Science.gov (United States)

    Chen, D. Y.

    1975-01-01

    Two methodical approaches to the design of energy-storage reactors for a group of widely used dc-to-dc converters are presented. One of these approaches is based on a steady-state time-domain analysis of piecewise-linearized circuit models of the converters, while the other approach is based on an analysis of the same circuit models, but from an energy point of view. The design procedure developed from the first approach includes a search through a stored data file of magnetic core characteristics and results in a list of usable reactor designs which meet a particular converter's requirements. Because of the complexity of this procedure, a digital computer usually is used to implement the design algorithm. The second approach, based on a study of the storage and transfer of energy in the magnetic reactors, leads to a straightforward design procedure which can be implemented with hand calculations. An equation to determine the lower-bound volume of workable cores for given converter design specifications is derived. Using this computer lower-bound volume, a comparative evaluation of various converter configurations is presented.

  4. 100kW Energy Transfer Multiplexer Power Converter Prototype Development Project

    Energy Technology Data Exchange (ETDEWEB)

    S. Merrill Skeist; Richard H. (Dick) Baker; Anthony G.P. Marini; DOE Project Officer - Keith Bennett

    2006-03-21

    Project Final Report for "100kW Energy Transfer Multiplexer Power Converter Prototype Development Project" prepared under DOE grant number DE-FG36-03GO13138. This project relates to the further development and prototype construction/evaluation for the Energy Transfer Multiplexer (ETM) power converter topology concept. The ETM uses a series resonant link to transfer energy from any phase of a multiphase input to any phase of a multiphase output, converting any input voltage and frequency to any output voltage and frequency. The basic form of the ETM converter consists of an eight (8)-switch matrix (six phase power switches and two ground power switches) and a series L-C resonant circuit. Electronic control of the switches allows energy to be transferred in the proper amount from any phase to any other phase. Depending upon the final circuit application, the switches may be either SCRs or IGBTs. The inherent characteristics of the ETM converter include the following: Power processing in either direction (bidirectional); Large voltage gain without the need of low frequency magnetics; High efficiency independent of output load and frequency; Wide bandwidth with fast transient response and; Operation as a current source. The ETM is able to synthesize true sinusoidal waveforms with low harmonic distortions. For a low power PM wind generation system, the ETM has the following characteristics and advantages: It provides voltage gain without the need of low frequency magnetics (DC inductors) and; It has constant high efficiency independent of the load. The ETM converter can be implemented into a PM wind power system with smaller size, reduced weight and lower cost. As a result of our analyses, the ETM offers wind power generation technology for the reduction of the cost and size as well as the increase in performance of low power, low wind speed power generation. This project is the further theoretical/analytical exploration of the ETM converter concept in relationship to

  5. Design considerations for a thermophotovoltaic energy converter using heat pipe radiators

    Energy Technology Data Exchange (ETDEWEB)

    Ashcroft, J.; DePoy, D. [Lockheed Martin Corp., Schenectady, NY (United States)

    1997-06-01

    The purpose of this paper is to discuss concepts for using high temperature heat pipes to transport energy from a heat source to a thermophotovoltaic (TPV) converter. Within the converter, the condenser portion of each heat pipe acts as a photon radiator, providing a radiant flux to adjacent TPV cells, which in turn create electricity. Using heat pipes in this way could help to increase the power output and the power density of TPV systems. TPV systems with radiator temperatures in the range of 1,500 K are expected to produce as much as 3.6 W/cm{sup 3} of heat exchanger volume at an efficiency of 20% or greater. Four different arrangements of heat pipe-TPV energy converters are considered. Performance and sizing calculations for each of the concepts are presented. Finally, concerns with this concept and issues which remain to be considered are discussed.

  6. Parameter based design of a twin-cylinder wave energy converter for real sea-states

    CERN Document Server

    Xu, Dali; Stiassnie, Michael

    2016-01-01

    We discuss the hydrodynamics of a wave energy converter consisting of two vertically floating, coaxial cylinders connected by dampers and allowed to heave, sway and roll. This design, viable in deep water and able to extract energy independent of the incident wave direction, is examined for monochromatic waves as well as broad-banded seas described by a Pierson Moskowitz spectrum. Several possible device sizes are considered, and their performance is investigated for a design spectrum, as well as for more severe sea states, with a view towards survivability of the converters. In terms of device motions and captured power, a quantitative assessment of converter design as it relates to survival and operation is provided. Most results are given in dimensionless form to allow for a wide range of applications.

  7. A Three-Phase Dual-Input Matrix Converter for Grid Integration of Two AC Type Energy Resources

    DEFF Research Database (Denmark)

    Liu, Xiong; Wang, Peng; Chiang Loh, Poh

    2013-01-01

    This paper proposes a novel dual-input matrix converter (DIMC) to integrate two three-phase ac type energy resources to a power grid. The proposed matrix converter is developed based on the traditional indirect matrix converter under reverse power flow operation mode, but with its six...

  8. On theory and simulation of heaving-buoy wave-energy converters with control

    Energy Technology Data Exchange (ETDEWEB)

    Eidsmoen, H.

    1995-12-01

    Heaving-buoy wave-energy converters with control were studied. The buoy is small compared to the wavelength. The resonance bandwidth is then narrow and the energy conversion in irregular waves can be significantly increased if the oscillatory motion of the device can be actively controlled, and the power output from the converter will vary less with time than the wave power transport. A system of two concentric cylinders of the same radius, oscillating in heave only, is analysed in the frequency-domain. The mathematical model can be used to study a tight-moored buoy, as well as a buoy reacting against a submerged body. The knowledge of the frequency-domain hydrodynamic parameters is used to develop frequency-domain and time-domain mathematical models of heaving-buoy wave energy converters. The main emphasis is on using control to maximize the energy production and to protect the machinery of the wave-energy converter in very large waves. Three different methods are used to study control. (1) In the frequency-domain explicit analytical expressions for the optimum oscillation are found, assuming a continuous sinusoidal control force, and from these expressions the optimum time-domain oscillation can be determined. (2) The second method uses optimal control theory, using a control variable as the instrument for the optimisation. Unlike the first method, this method can include non-linearities. But this method gives numerical time series for the state variables and the control variable rather than analytical expressions for the optimum oscillation. (3) The third method is time-domain simulation. Non-linear forces are included, but the method only gives the response of the system to a given incident wave. How the different methods can be used to develop real-time control is discussed. Simulations are performed for a tight-moored heaving-buoy converter with a high-pressure hydraulic system for energy production and motion control. 147 refs., 38 figs., 22 tabs.

  9. CFD study of the overtopping discharge of the Wave Dragon wave energy converter

    DEFF Research Database (Denmark)

    Eskilsson, K.; Palm, J.; Kofoed, Jens Peter

    2015-01-01

    The Wave Dragon is a floating Wave Energy Converter (WEC) working by the overtopping principle. The overtopping discharge has been determined by model scale experiments in wave basins. In the present study we numerically simulate the overtopping behavior of the Wave Dragon device using a VOFbased...

  10. Structural Modeling and Analysis of a Wave Energy Converter Applying Dynamical Substructuring Method

    DEFF Research Database (Denmark)

    Zurkinden, Andrew Stephen; Damkilde, Lars; Gao, Zhen

    2013-01-01

    This paper deals with structural modeling and analysis of a wave energy converter. The device, called Wavestar, is a bottom fixed structure, located in a shallow water environment at the Danish Northwest coast. The analysis is concentrated on a single float and its structural arm which connects...

  11. Experimental Hydraulic Optimization of the Wave Energy Converter Seawave Slot-Cone Generator

    DEFF Research Database (Denmark)

    Kofoed, Jens Peter

    This report presents the results of a experimental hydraulic optimization of the wave energy convert (WEC) Seawave Slot-Cone Generator (SSG). SSG is a WEC utilizing wave overtopping in multiple reservoirs. In the present SSG setup three reservoirs has been used. Model tests have been performed...

  12. Experimental Validation of aWave Energy Converter Array Hydrodynamics Tool

    DEFF Research Database (Denmark)

    Ruiz, Pau Mercadé; Ferri, Francesco; Kofoed, Jens Peter

    2017-01-01

    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...

  13. Optimising Reactive Control in non-ideal Efficiency Wave Energy Converters

    DEFF Research Database (Denmark)

    Strager, Thomas; Lopez, Pablo Fernandez; Giorgio, Giuseppe

    2014-01-01

    When analytically optimising the control strategy in wave energy converters which use a point absorber, the efficiency aspect is generally neglected. The results presented in this paper provide an analytical expression for the mean harvested electrical power in non-ideal efficiency situations...

  14. Investigation of Wave Transmission from a Floating Wave Dragon Wave Energy Converter

    DEFF Research Database (Denmark)

    Nørgaard, Jørgen Harck; Andersen, Thomas Lykke

    2012-01-01

    This paper focuses on the calibration of the MIKE21BW model against the measured wave height reduction behind a 24 kW/m Wave Dragon (WD) wave energy converter. A numerical model is used to determine the wave transmission through the floating WD in varying wave conditions. The transmission obtained...

  15. Turbine Control Strategy using Wave Prediction to Optimise Power Take Off of Overtopping Wave Energy Converters

    DEFF Research Database (Denmark)

    Tedd, James; Knapp, Wilfried; Frigaard, Peter;

    2005-01-01

    This paper presents the control strategy used on Wave Dragon overtopping wave energy converter. The nature of overtopping requires that for optimum performance the water level in the reservoir must be controlled by controlling the turbine outflows. A history of the simulations performed is included...

  16. Ultimate Limit State Model Basis for Assessment of Offshore Wind Energy Converters

    DEFF Research Database (Denmark)

    Thöns, S.; Faber, M. H.; Rücker, W.

    2012-01-01

    This paper establishes the model basis regarding the ultimate limit state consisting of structural, loading, and probabilistic models of the support structure of offshore wind energy converters together with a sensitivity study. The model basis is part of a risk based assessment and monitoring...

  17. Control of a 420 KN Discrete Displacement Cylinder Drive for the Wavestar Wave Energy Converter

    DEFF Research Database (Denmark)

    Hansen, Rico H.; Andersen, Torben Ole; Pedersen, Henrik C.

    2014-01-01

    To improve the power production of their 1 MW wave energy converter, Wavestar is developing a new transmission based on discrete hydraulics. The discrete hydraulic system allows all cylinders to supply a common accumulator storage while maintaining low-loss individual force control of the 20 abso...

  18. Energy harvesting from an exercise bike using a switch-mode converter controlled generator

    DEFF Research Database (Denmark)

    Knott, Arnold; Lindberg-Poulsen, Kristian; Andersen, Thomas

    2010-01-01

    This paper investigates the feasibility of using an alternator as means of harvesting energy from a stationary exercise bicycle. A switch mode converter was designed to regulate the current in the alternator rotor winding, thus regulating the power required to pedal, and consequently the power...

  19. Experimental modelling of the overtopping flow on the Wave Dragon Wave Energy Converter

    Energy Technology Data Exchange (ETDEWEB)

    Parmeggiani, S.; Kofoed, J.P.

    2010-11-15

    The Wave Dragon is a floating slack-moored Wave Energy Converter (WEC) of the overtopping type. Oncoming waves are focused by two wing reflectors towards the ramp of the device, surge-up and overtop into a reservoir placed at a higher level than the surface of the sea. The energy production takes place as the water is led back to the sea through a set of low-head hydro-turbines. After many years of development, Wave Dragon (WD) is now facing the phase of pre-commercial demonstration. In this phase it is very important to be able to use the available data to predict the performances of the device at different scales and locations. A flexible and comprehensive modelling tool is therefore highly required. Wave Dragon produces power through different steps of energy conversion: 1. Primary energy conversion: overtopping - The energy content of the wave (partly in the kinetic and partly in the potential form) is transferred to the device in the form of volumes of water coming into the reservoir. These volumes are stored at a higher level than the surrounding sea, being a stock of potential energy. 2. Secondary energy conversion: turbines - The potential energy stored in the reservoir is transformed into mechanical energy as the water flows back to the sea, activating the lowhead hydro-turbines. 3. Tertiary energy conversion step: generators - The turbines shaft rotation activates the permanent magnet generators, converting mechanical energy into electrical energy. 4. Grid connection and delivery of the power - The electricity produced is delivered to the grid at the right frequency, by means of a frequency converter. The present research is focused on the overtopping. Being the primary energy conversion mechanism of the WD, the overtopping is indeed the stage where the performances of the device are influenced by local conditions and the geometric features of the set-up. This makes it the right step where to account for these features through an accurate modelling

  20. Why flavins are not competitors of chlorophyll in the evolution of biological converters of solar energy.

    Science.gov (United States)

    Kritsky, Mikhail S; Telegina, Taisiya A; Vechtomova, Yulia L; Buglak, Andrey A

    2012-12-27

    Excited flavin molecules can photocatalyze reactions, leading to the accumulation of free energy in the products, and the data accumulated through biochemical experiments and by modeling prebiological processes suggest that flavins were available in the earliest stages of evolution. Furthermore, model experiments have shown that abiogenic flavin conjugated with a polyamino acid matrix, a pigment that photocatalyzes the phosphorylation of ADP to form ATP, could have been present in the prebiotic environment. Indeed, excited flavin molecules play key roles in many photoenzymes and regulatory photoreceptors, and the substantial structural differences between photoreceptor families indicate that evolution has repeatedly used flavins as chromophores for photoreceptor proteins. Some of these photoreceptors are equipped with a light-harvesting antenna, which transfers excitation energy to chemically reactive flavins in the reaction center. The sum of the available data suggests that evolution could have led to the formation of a flavin-based biological converter to convert light energy into energy in the form of ATP.

  1. Progress Towards the Development of a Traveling Wave Direct Energy Converter for Aneutronic Fusion Propulsion Applications

    Science.gov (United States)

    Tarditi, A. G.; Chap, A.; Wolinsky, J.; Scott, J. H.

    2015-01-01

    A coordinated experimental and theory/simulation effort has been carried out to investigate the physics of the Traveling Wave Direct Energy Converter (TWDEC), a scheme that has been proposed in the past for the direct conversion into electricity of the kinetic energy of an ion beam generated from fusion reactions. This effort has been focused in particular on the TWDEC process in the high density beam regime, thus accounting for the ion beam expansion due to its space charge.

  2. Mass-modulation schemes for a class of wave energy converters: Experiments, models, and efficacy

    OpenAIRE

    Diamond, CA; Judge, CQ; Orazov, B; Savaş, Ö; O'Reilly, OM

    2015-01-01

    © 2015, Elsevier Ltd. All rights reserved. In a recent series of works, mass-modulation schemes have been proposed for a class of ocean wave energy converter (WEC). The goal of the schemes is to improve the energy harvesting capabilities of these devices by taking advantage of the ambient water. However this improvement comes at the cost of increased system complexity and possible impulse loadings at the instances where the mass changes. In the present work, experimental results for a pair of...

  3. High-efficiency, monolithic, multi-bandgap, tandem photovoltaic energy converters

    Science.gov (United States)

    Wanlass, Mark W.

    2011-11-29

    A monolithic, multi-bandgap, tandem solar photovoltaic converter has at least one, and preferably at least two, subcells grown lattice-matched on a substrate with a bandgap in medium to high energy portions of the solar spectrum and at least one subcell grown lattice-mismatched to the substrate with a bandgap in the low energy portion of the solar spectrum, for example, about 1 eV.

  4. High step-up isolated efficient single switch DC-DC converter for renewable energy source

    Directory of Open Access Journals (Sweden)

    A. Gopi

    2014-12-01

    Full Text Available In this paper, an isolated high step-up single switch DC-DC converter for renewable energy source is proposed. In the proposed converter high step-up voltage is obtained by single power switching technique that operates low duty cycle with isolated transformer inductors and switched capacitors and power diodes. The disadvantage of conventional converters is that it has high duty ratio and high voltage stress on power devices with less efficiency. The proposed converter eliminates the switching losses and recycles the leakage energy which includes reverse recovery energy of the power diode by using passive clamp circuit. To achieve high output voltage gain, the isolated transformer primary terminal and secondary terminal are connected in series during switching operation. PSIM software has been used for simulation. Simulation circuit is analyzed at 40Vdc/400Vdc, 200 W and this operation is validated by implementing in the hardware model at 12Vdc/120Vdc, 60 W.

  5. Adaptive sliding mode control of interleaved parallel boost converter for fuel cell energy generation system

    DEFF Research Database (Denmark)

    El Fadil, H.; Giri, F.; Guerrero, Josep M.

    2013-01-01

    This paper deals with the problem of controlling energy generation systems including fuel cells (FCs) and interleaved boost power converters. The proposed nonlinear adaptive controller is designed using sliding mode control (SMC) technique based on the system nonlinear model. The latter accounts...... for the boost converter large-signal dynamics as well as for the fuel-cell nonlinear characteristics. The adaptive nonlinear controller involves online estimation of the DC bus impedance ‘seen’ by the converter. The control objective is threefold: (i) asymptotic stability of the closed loop system, (ii) output...... voltage regulation under bus impedance uncertainties and (iii) equal current sharing between modules. It is formally shown, using theoretical analysis and simulations, that the developed adaptive controller actually meets its control objectives....

  6. New topology for DC/DC bidirectional converter for hybrid systems in renewable energy

    Science.gov (United States)

    Lopez, Juan Carlos; Ortega, Manuel; Jurado, Francisco

    2015-03-01

    This article presents a new isolated DC/DC bidirectional converter with soft switching, using a transformer with two voltage taps and two full bridges with insulated-gate bipolar transistors (IGBTs), one on each side of the transformer to be integrated in hybrid systems of renewable energy. A large voltage conversion ratio can be achieved using this converter, in buck and booster modes. Also medium and high DC power can be converted with a good efficiency. Analysis and switching techniques have been reported. To verify the principle of operation, a laboratory prototype of 10 kW has been performed. Experimental results are presented, operating in boost mode. The switching algorithm used has been modelled in MATLAB-Simulink to generate C code. This code has been implemented in a DSP F2812, which has been used to build the prototype.

  7. Current Source Converter Based Multi-terminal DC Wind Energy Conversion System

    Institute of Scientific and Technical Information of China (English)

    Shixiong FAN; Guangyi LIU; Zhanyong YANG; Weiwei MA; Barry W.WILLIAMS

    2013-01-01

    A current source converter based multi-terminal direct current (DC) wind energy conversion system (WECS) is proposed.The current source DC/DC converter is adopted to connect a wind turbine to an inverter with maximum power point control.Each turbine is associated with a DC source by parallel-connected to a common DC link.After DC power collection,a current source inverter (CSI) using gate turn-off components is used for the grid connection due to its flexible reactive power control and short circuit protection capabilities.For such a parallel connection configuration,the CSI operates in an input voltage control mode,which maintains the DC link voltage constant.The dynamic responses of combined mechanical and electrical systems are investigated with three different operation cases.Simulation and experimental results demonstrate the feasibility and stability of the current source DC/DC converter based multi-terminal DC WECS.

  8. Three-dimensional models of conventional and vertical junction laser-photovoltaic energy converters

    Science.gov (United States)

    Heinbockel, John H.; Walker, Gilbert H.

    1988-01-01

    Three-dimensional models of both conventional planar junction and vertical junction photovoltaic energy converters have been constructed. The models are a set of linear partial differential equations and take into account many photoconverter design parameters. The model is applied to Si photoconverters; however, the model may be used with other semiconductors. When used with a Nd laser, the conversion efficiency of the Si vertical junction photoconverter is 47 percent, whereas the efficiency for the conventional planar Si photoconverter is only 17 percent. A parametric study of the Si vertical junction photoconverter is then done in order to describe the optimum converter for use with the 1.06-micron Nd laser. The efficiency of this optimized vertical junction converter is 44 percent at 1 kW/sq cm.

  9. Reliability-based Calibration of Partial Safety Factors for Wave Energy Converters

    DEFF Research Database (Denmark)

    Ambühl, Simon; Kramer, Morten Mejlhede; Sørensen, John Dalsgaard

    2015-01-01

    of partial safety factors for design of welded details for wave energy converter applications is presented in this paper using probabilistic methods. The paper presents an example with focus on the Wavestar device. SN curves and Rainflow counting are used to model fatigue without considering inspections......Wave energy converters (WECs), which harvest energy from the waves and transfer them to electricity, are a new technology, where structural standards need to be developed. An important step towards standardization is the calibration of partial safety factors. A methodology for calibration....... The influence of inspections is modelled using a fracture mechanics approach, which is calibrated by the SN curve approach. Furthermore, the paper assesses the influence of the inspection quality. The results show that with multiple inspections during the lifetime of the device and by applying a good inspection...

  10. Grid Connected Wind Energy Conversion System Using Three Phase Matrix Converter

    Directory of Open Access Journals (Sweden)

    R.A. Priya

    2015-01-01

    Full Text Available A variable speed Wind Energy Conversion System (WECS with Permanent Magnet Synchronous Generator (PMSG connected to grid through Matrix Converter (MC is proposed in this study. Necessity for increased demand in electrical energy paved way for use of renewable energy sources, one of which is abundant wind energy available in ample. Various Wind Energy Conversion systems have been proposed over the decades, of which various topologies had been projected, where complex topologies are being in existence. Permanent magnet synchronous generator has substantial advantages over conventional generators like less weight and volume and exemption for separate excitation with high precision. The conventional system involves two stage of conversion involving rectification followed by inversion being coupled by a DC link capacitor before fed to a grid, which decreases the efficiency of the system due to power quality issue. To overcome this matrix converter can be utilized to transfer the power from generation stage to the grid; there by an AC-AC converter can transfer power from generator to the grid. The proposed system is designed and tested in MATALB/Simulink environment and the results are effective.

  11. Enhanced Passive RF-DC Converter Circuit Efficiency for Low RF Energy Harvesting.

    Science.gov (United States)

    Chaour, Issam; Fakhfakh, Ahmed; Kanoun, Olfa

    2017-03-09

    For radio frequency energy transmission, the conversion efficiency of the receiver is decisive not only for reducing sending power, but also for enabling energy transmission over long and variable distances. In this contribution, we present a passive RF-DC converter for energy harvesting at ultra-low input power at 868 MHz. The novel converter consists of a reactive matching circuit and a combined voltage multiplier and rectifier. The stored energy in the input inductor and capacitance, during the negative wave, is conveyed to the output capacitance during the positive one. Although Dickson and Villard topologies have principally comparable efficiency for multi-stage voltage multipliers, the Dickson topology reaches a better efficiency within the novel ultra-low input power converter concept. At the output stage, a low-pass filter is introduced to reduce ripple at high frequencies in order to realize a stable DC signal. The proposed rectifier enables harvesting energy at even a low input power from -40 dBm for a resistive load of 50 kΩ. It realizes a significant improvement in comparison with state of the art solutions.

  12. Estimation of Bidirectional Buck/boost DC/DC Converters with Electric Double-Layer Capacitors for Energy Storage Systems

    Science.gov (United States)

    Funabiki, Shigeyuki; Yamamoto, Masayoshi

    Renewable energy such as wind force and solar light has collected the attention as alternative energy sources of fossil fuel. An energy storage system with an electric double-layer capacitor (EDLC), which balances the demand and supply power, is required in order to introduce the electric power generating system that utilizes renewable energy. Currently, the research and development of these energy storage systems are actively carried out. In the energy storage system with an EDLC, the DC/DC converter having the function of the bidirectional power flow and the buck/boost performance is essential as an interface and power control circuit. There are two types of the bidirectional buck/boost DC/DC converters. One type consists of two buck/boost DC/DC converters with one reactor. The other type consists of two sets of two-quadrant DC/DC converters with one reactor. This paper discusses the comparison of these types of DC/DC converters with bidirectional power flow and buck/boost performance. The two types of DC/DC converters are estimated for their application to the energy storage system with the EDLC. As the voltage endurance of the device is lower and the mean current is smaller in the latter type of converter despite of having twice the number of devices compared to the former, the latter type of converter has the advantage of a smaller reactor, i.e., core volume and loss, and lower loss in the converter.

  13. Investigation on the energy absorption performance of a fixed-bottom pressure-differential wave energy converter

    Energy Technology Data Exchange (ETDEWEB)

    Babarit, A.; Wendt, F.; Yu, Y. -H.; Weber, J.

    2017-04-01

    In this article, we investigate the energy absorption performance of a fixed-bottom pressure-differential wave energy converter. Two versions of the technology are considered: one has the moving surfaces on the bottom of the air chambers whereas the other has the moving surfaces on the top. We developed numerical models in the frequency domain, thereby enabling the power absorption of the two versions of the device to be assessed. It is observed that the moving surfaces on the top allow for easier tuning of the natural period of the system. Taking into account stroke limitations, the design is optimized. Results indicate that the pressure-differential wave energy converter is a highly efficient technology both with respect to energy absorption and selected economic performance indicators.

  14. Converter-based accumulation of electric energy generated by microbial biofuel cell

    Science.gov (United States)

    Reshetilov, A. N.; Kitova, A. E.; Dyakov, A. V.; Gotovtsev, P. M.; Vasilov, R. G.; Gutorov, M. A.

    2017-01-01

    Microbial biofuel cell (BFC) was used as a primary energy source for energy storage system. The converter BQ25504 (Texas Instruments) was applied for transformation of electrical energy from microwatt primary sources. The energy storage operation begins if BFC output voltage was higher or equal to 300 mV. In case of stationary operation it was possible to provide energy storage of BFC output voltage equal to 100 mV. The developed system based on converter enables to increase the initial voltage BFC of 0.5 V to 3.1 V; accumulated energy is stored on the various capacitors. Resulting voltage was stable with application of condensers with capacities from 100 μF to 6800 μF. In case of application of 3.1 V and 6800 μF condenser the storage energy was equal to 32.7 mJ. It was enough to provide short time operation of diode L-1154SURDK (2.0 V, 20 mA) and electrical motor M25E-4L (MITSUMI; 3.0 V, 100 mA). Designed system can be applied for energy supply of small electrical devices (for example remote sensors) and autonomous microrobots.

  15. Optimisation of Working Areas in Discrete Hydraulic Power Take off-system for Wave Energy Converters

    DEFF Research Database (Denmark)

    Hansen, Anders Hedegaard; Hansen, Rico Hjerm; Pedersen, Henrik C.

    2012-01-01

    Fluid power is the leading technology in Power Take Off(PTO) systems in Wave Energy Converters(WEC’s), due to the capability of generating high force at low velocity. However, as hydraulic force controlling system may suffer from large energy losses the efficiency of the hydraulic PTO systems may...... be a limiting factor for wave energy. Therefore, a secondary controlled force system has been proposed as PTO element for WEC’s. This paper investigates the configuration of a multi-chamber cylinder utilising two common pressure lines. By usage of model based optimisation an optimal number and size of working...

  16. User guide - COE calculation tool for wave energy converters. Draft version 1

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez-Chozas, J.; Kofoed, J.P. [Aalborg Univ., Aalborg (Denmark); Helstrup Jensen, N.E. [Energinet.dk, Fredericia (Denmark)

    2013-08-15

    Aalborg University together with Energinet.dk and Julia F. Chozas Consulting Engineer, have released a freely available online spreadsheet to evaluate the Levelised Cost of Energy (LCOE) for wave energy projects. The open-access tool calculates the LCOE based on the power production of a Wave Energy Converter (WEC) at a particular location. Production data may derive from laboratory testing, numerical modelling or from sea trials. The tool has been developed as a transparent and simple model that evaluates WEC's economic feasibility in a range of locations, while scaling WEC's features to the selected site. (Author)

  17. Experimental Wave Tank Test for Reference Model 3 Floating-Point Absorber Wave Energy Converter Project

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Y. H. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Lawson, M. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Li, Y. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Previsic, M. [Re Vision Consulting, Sacramento, CA (United States); Epler, J. [Re Vision Consulting, Sacramento, CA (United States); Lou, J. [Oregon State Univ., Corvallis, OR (United States)

    2015-01-01

    The U.S. Department of Energy established a reference model project to benchmark a set of marine and hydrokinetic technologies including current (tidal, open-ocean, and river) turbines and wave energy converters. The objectives of the project were to first evaluate the status of these technologies and their readiness for commercial applications. Second, to evaluate the potential cost of energy and identify cost-reduction pathways and areas where additional research could be best applied to accelerate technology development to market readiness.

  18. Preliminary Analysis of an Oscillating Surge Wave Energy Converter with Controlled Geometry: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Tom, Nathan; Lawson, Michael; Yu, Yi-Hsiang; Wright, Alan

    2015-09-09

    The aim of this paper is to present a novel wave energy converter device concept that is being developed at the National Renewable Energy Laboratory. The proposed concept combines an oscillating surge wave energy converter with active control surfaces. These active control surfaces allow for the device geometry to be altered, which leads to changes in the hydrodynamic properties. The device geometry will be controlled on a sea state time scale and combined with wave-to-wave power-take-off control to maximize power capture, increase capacity factor, and reduce design loads. The paper begins with a traditional linear frequency domain analysis of the device performance. Performance sensitivity to foil pitch angle, the number of activated foils, and foil cross section geometry is presented to illustrate the current design decisions; however, it is understood from previous studies that modeling of current oscillating wave energy converter designs requires the consideration of nonlinear hydrodynamics and viscous drag forces. In response, a nonlinear model is presented that highlights the shortcomings of the linear frequency domain analysis and increases the precision in predicted performance.

  19. Power Take-Off Simulation for Scale Model Testing of Wave Energy Converters

    Directory of Open Access Journals (Sweden)

    Scott Beatty

    2017-07-01

    Full Text Available Small scale testing in controlled environments is a key stage in the development of potential wave energy conversion technology. Furthermore, it is well known that the physical design and operational quality of the power-take off (PTO used on the small scale model can have vast effects on the tank testing results. Passive mechanical elements such as friction brakes and air dampers or oil filled dashpots are fraught with nonlinear behaviors such as static friction, temperature dependency, and backlash, the effects of which propagate into the wave energy converter (WEC power production data, causing very high uncertainty in the extrapolation of the tank test results to the meaningful full ocean scale. The lack of quality in PTO simulators is an identified barrier to the development of WECs worldwide. A solution to this problem is to use actively controlled actuators for PTO simulation on small scale model wave energy converters. This can be done using force (or torque-controlled feedback systems with suitable instrumentation, enabling the PTO to exert any desired time and/or state dependent reaction force. In this paper, two working experimental PTO simulators on two different wave energy converters are described. The first implementation is on a 1:25 scale self-reacting point absorber wave energy converter with optimum reactive control. The real-time control system, described in detail, is implemented in LabVIEW. The second implementation is on a 1:20 scale single body point absorber under model-predictive control, implemented with a real-time controller in MATLAB/Simulink. Details on the physical hardware, software, and feedback control methods, as well as results, are described for each PTO. Lastly, both sets of real-time control code are to be web-hosted, free for download, modified and used by other researchers and WEC developers.

  20. Hybrid Non-Isolated and Non Inverting Nx Interleaved DC-DC Multilevel Boost Converter for Renewable Energy Applications

    DEFF Research Database (Denmark)

    Bhaskar, Mahajan Sagar; Kulkarni, Rishi M.; Padmanaban, Sanjeevi Kumar;

    2016-01-01

    In this paper hybrid non isolated/ non inverting Nx interleaved DC-DC multilevel Boost Converter for renewable energy applications is presented. The presented hybrid topology is derived from the conventional interleaved converter and the Nx Multilevel boost converter. In renewable energy...... applications, generated energy cannot be directly used at application end. In most of the cases it needs to be stepped up with DC-DC converter at operating voltage levels as per the requirement of the application. Though conventional boost converter can theoretically be used for this purpose, but obtaining....... The advantages of presenting topology of DC-DC converter are high voltage conversion, reduce ripple, low voltage stress, non inverting without utilizing the high duty and transformer. The main advantage of presented topology is more number of levels can be increased by adding capacitor and diode circuitry...

  1. Investigation of a Novel Mechanical to Thermal Energy Converter Based on the Inverse Problem of Electric Machines

    Directory of Open Access Journals (Sweden)

    Lei Chen

    2016-07-01

    Full Text Available A novel converter that can directly transform electrical, wind, hydraulic and other types of mechanical energy into thermal energy is presented in this study. First, the thermal energy of the converter is classified and then calculated by a finite element method. The eddy current distribution in the stator of the converter is also discussed. Second, the temperature field of the converter is calculated using a boundary element method. Subsequently, a thermal power–temperature coupled calculation method is presented to calculate the actual thermal power and temperature of the converter. The characteristic curves of the actual thermal power and the increase in water flow temperature are then presented based on the calculation results. Lastly, an experimental system is built, the thermal power and temperature of the converter are measured and the experimental results and the analytical calculations are compared.

  2. Advanced Energy Conversion System Using Sinusoidal Voltage Tracking Buck-Boost Converter Cascaded Polarity Changing Inverter

    Science.gov (United States)

    Ahmed, Nabil A.

    2011-06-01

    This paper presents an advanced power converter employs a sinusoidal voltage absolute value tracking buck-boost DC-DC converter in the first power processing stage and a polarity changing full-bridge inverter in the second stage. The proposed power conversion system has the capability of delivering sinusoidal output and input current with unity power factor and good output voltage regulation. Consequently, the complete voltage regulator system, which is mainly suitable for new energy generation systems as well as energy storage systems, can be constructed compactly and inexpensively without DC link electrolytic capacitor. Also, the paper presents an auxiliary passive resonant circuit for soft switching operation. Simulation results using PSIM software are presented to verify the operation principles and feasibility of the proposed power conversion system.

  3. Extrapolation of extreme response for different mooring line systems of floating wave energy converters

    DEFF Research Database (Denmark)

    Ambühl, Simon; Sterndorff, Martin; Sørensen, John Dalsgaard

    2014-01-01

    Mooring systems for floating wave energy converters (WECs) are a major cost driver. Failure of mooring systems often occurs due to extreme loads. This paper introduces an extrapolation method for extreme response which accounts for the control system of a WEC that controls the loads onto the stru......Mooring systems for floating wave energy converters (WECs) are a major cost driver. Failure of mooring systems often occurs due to extreme loads. This paper introduces an extrapolation method for extreme response which accounts for the control system of a WEC that controls the loads onto...... the structure and the harvested power of the device as well as the fact that extreme loads may occur during operation and not at extreme wave states when the device is in storm protection mode. The extrapolation method is based on shortterm load time series and applied to a case study where up-scaled surge load...

  4. Hydrodynamic Behavior of Overtopping Wave Energy Converters Built in Sea Defense Structures

    DEFF Research Database (Denmark)

    Victor, Lander; Kofoed, Jens Peter; Troch, Peter

    2010-01-01

    Many sea defense structures need to be adapted to the rising sea water level and changing wave climate due to global warming. The accordingly required investment opens perspectives for wave energy converters (WECs) – that are built as part of the sea defense structures – to become economically...... viable. In this paper the average overtopping discharges q of overtopping wave energy devices built in sea defense structures are studied. Physical model tests with this type of devices have been carried out in a wave flume leading to experimental q - values. The experimental q -values are compared...... with predicted average overtopping discharges by existing empirical formulae from literature. Overtopping converters have low relative crest freeboards and smooth slope characteristics to maximize overtopping, which is contradictive to the basic role of sea defense structures. As a consequence, the achieved...

  5. Specification of Instrumentation of Multi MW Wave Dragon Offshore Wave Energy Converter

    DEFF Research Database (Denmark)

    Gilling, Lasse; Kofoed, Jens Peter

    Wave Dragon is a wave energy converter of the overtopping type and is described e.g. in Tedd et. al. (2006). The device has been thoroughly tested on a 1:51.8 scale model in wave laboratories and a 1:4.5 scale model deployed in Nissum Bredning, a large inland waterway in Denmark. Based on the exp......Wave Dragon is a wave energy converter of the overtopping type and is described e.g. in Tedd et. al. (2006). The device has been thoroughly tested on a 1:51.8 scale model in wave laboratories and a 1:4.5 scale model deployed in Nissum Bredning, a large inland waterway in Denmark. Based...

  6. Pemodelan Sistem Hidrolis Terhadap Variasi Tinggi Gelombang Air Laut Pada Sistem Wave Energy Hyperbaric Converter (WEHC

    Directory of Open Access Journals (Sweden)

    Frengki Mohamad Felayati

    2015-12-01

    Full Text Available Perbedaan karakteristik gelombang berpengaruh terhadap listrik yang dihasilkan pembangkit listrik tenaga gelombang laut. Termasuk WEHC (Wave Energy Hyperbaric Converter dalam instalasinya perlu dianalisa aliran energi terhadap variasi tinggi gelombang air laut dan mengetahui tinggi gelombang optimum untuk instalasinya. Sistem ini bekerja dengan sub sistem antara lain buoy, arm, hydraulic pump, hyperbaric accumulator, hyperbaric chamber, dan turbin pelton. Sistem bekerja secara tertutup dengan menggunakan fluida fresh water. Implementasi dari converter ini yaitu di daerah pantai curam atau dengan rekayasa struktur yang sesuai. Pembuatan simulasi menggunakan MATLAB Simulink dengan memvariasikan tinggi gelombang laut antara 1 – 2 m dan periode gelombang 5 – 7 m. Rancangan sistem ini menghasilkan daya terkecil 8.8 kW yaitu pada periode gelombang 7 s dan tinggi gelombang 1 m. Sedangkan daya terbesar yaitu 24.9 kW pada periode gelombang 5 s dan tinggi gelombang 2 m dengan efisiensi sebesar 82.8%.

  7. A Back-to-Back 2L-3L Grid Integration of a Marine Current Energy Converter

    Directory of Open Access Journals (Sweden)

    Senad Apelfröjd

    2015-01-01

    Full Text Available The paper proposes a back-to-back 2L-3L grid connection topology for a marine current energy converter. A prototype marine current energy converter has been deployed by a research group at Uppsala University. The concept behind the prototype revolves around a fixed pitch vertical axis turbine directly connected to a permanent magnet synchronous generator (PMSG. The proposed grid connection system utilizes a well known and proven two level voltage source converter generator-side combined with a three-level cascaded H-bridge (CHB multilevel converter grid-side. The multilevel converter brings benefits in terms of efficiency, power quality and DC-link utilization. The system is here presented for a single marine current energy converter but can easily be scaled up for clusters of marine current energy converters. Control schemes for both grid-side and generator-side voltage source converters are presented. The start-up, steady state and dynamic performance of the marine current energy converter are investigated and simulation results are presented in this paper.

  8. Energy storage device based on flywheel, power converters and Simulink real-time

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Kedra, Bartosz; Malkowski, Robert

    2017-01-01

    as well as proposed and introduced functions are listed. Implementation details are given in third section of paper. Hardware structure is presented and described. Information about used communication interface, data maintenance and storage solution, as well as used Simulink realtime features...... are presented. List and description of all measurements is provided. In the last section of the paper results of experiments using Energy Storage Device based on Flywheel and Power Converters performed in laboratory are presented....

  9. Geometrical Optimization for Improved Power Capture of Multi-Level Overtopping Based Wave Energy Converters

    DEFF Research Database (Denmark)

    Margheritini, Lucia; Victor, L.; Kofoed, Jens Peter

    2009-01-01

    In multi-level wave energy converters the water from incoming waves is stored in reservoirs one on top of the other. Prevision formula for the overtopping flow rates in the individual reservoirs is fundamental for dimensioning correctly the turbines and optimizing the device. Having a number...... words, the opening between two consecutive reservoirs. 13 different geometries have been tested in 2D irregular waves and a new formulation for prediction of overtopping in multilevel structures is presented....

  10. Sliding mode control of boost converter: Application to energy storage system via supercapacitors

    OpenAIRE

    Hijazi, Alaa; Di Loreto, Michaël; BIDEAUX, Eric; Venet, Pascal; Clerc, Guy; Rojat, Gérard

    2009-01-01

    INSPEC Accession Number: 10939325; International audience; Sliding mode control of boost converter is studied. In order to improve dynamical performances with static and dynamic specifications, we propose a systematic procedure to compute the gains of the controller based on an optimization scheme. This method is applied to the control of an energy storage system based on supercapacitors technology in order to regulate the output voltage. Given a system with large variations of input voltage ...

  11. Extreme Loads on the Mooring Lines and Survivability Mode for the Wave Dragon Wave Energy Converter

    DEFF Research Database (Denmark)

    Parmeggiani, Stefano; Kofoed, Jens Peter; Friis-Madsen, E.

    2011-01-01

    One of the main challenges Wave Energy Converters have to face on the road towards commercialization is to ensure survivability in extreme condition at a reasonable capital costs. For a floating device like the Wave Dragon, a reliable mooring system is essential. The control strategy of the Wave...... by approximately 20-30% by lowering the crest level and balancing the device to lean a little towards the front....

  12. On forced oscillations of a simple model for a novel wave energy converter

    KAUST Repository

    Orazov, Bayram

    2011-05-11

    The dynamics of a simple model for an ocean wave energy converter is discussed. The model for the converter is a hybrid system consisting of a pair of harmonically excited mass-spring-dashpot systems and a set of four state-dependent switching rules. Of particular interest is the response of the model to a wide spectrum of harmonic excitations. Partially because of the piecewise-smooth dynamics of the system, the response is far more interesting than the linear components of the model would suggest. As expected with hybrid systems of this type, it is difficult to establish analytical results, and hence, with the assistance of an extensive series of numerical integrations, an atlas of qualitative results on the limit cycles and other forms of bounded oscillations exhibited by the system is presented. In addition, the presence of unstable limit cycles, the stabilization of the unforced system using low-frequency excitation, the peculiar nature of the response of the system to high-frequency excitation, and the implications of these results on the energy harvesting capabilities of the wave energy converter are discussed. © 2011 Springer Science+Business Media B.V.

  13. A SYSTEM TO MAKE USE OF EXISTING BREAKWATERS AS OVERTOPPING WAVE ENERGY CONVERTERS

    Directory of Open Access Journals (Sweden)

    DENIZ ÜNSALAN

    2016-06-01

    Full Text Available The main purpose of building breakwaters is to produce safe havens for ships and boats in rough seas. The general architecture for a breakwater is a wall with a trapezoidal -shaped cross section extending parallel to the shoreline. As the waves from the open sea approach, they are encountered by the so- called slope and revetment of the breakwater, where the wave is broken and its energy is dissipated and/or reflected back. However, the ever -increasing attractiveness of the utilization of waves as energy sources, paralleling to the increasing monetary and envir onmental costs of energy, has led the authors to consider the vast amounts of this otherwise dissipated energy into useful electrical energy. A wave energy conversion concept, which can be classified as an “overtopping” wave energy converter was conceived, where the open sea-facing (revetment side of the breakwater is fitted by a water collecting channel at a suitable height above the calm water level, running alongside the breakwater. The channel leads the collected water to a powerhouse containing a low head turbine (or a set of such turbines discharging it to the calm water of the inner harbour. Power obtained from these turbines can be converted to electrical energy. In this study, an estimation of the volume of water collected by the channel and the energy production for a proposed breakwater - power station system for a typical rough weather shall be made. It is deemed that the feasibility of this system is comparable to and even higher than the other wave energy conversion systems since it does not require additional facilities and power supply lines to be built due to its proximity to the existing energy transmission lines, except for the addition of new features/installations to the existing breakwaters.

  14. Numerical Analysis of a Large Floating Wave Energy Converter with Adjustable Structural Geometry

    DEFF Research Database (Denmark)

    Ferri, Francesco; Pecher, Arthur Francois Serge; Kofoed, Jens Peter

    2015-01-01

    The current cost of energy (CoE) from wave energy converters (WECs) is still significantly higher than other renewable energy resources, thus the sector has not yet reached a competitive level. WECs have a relative small turnover compared to the high capital cost, which to a large extent is driven...... by the structural loads in extreme conditions. TheWeptos is a large floating WEC, with multiple absorbers, which has proven to be a serious candidate for the renewable energy market, due to both relevant power performance and reduced cost if compared with other WECs. The scope of this article is to compare two...... different configurations of the Weptos machine, using the cost of energy (CoE) as a base of comparison. The numerical results are obtained via a multi-body analysis carried out in frequency domain....

  15. Experimental Modelling of the Overtopping Flow on the Wave Dragon Wave Energy Converter

    DEFF Research Database (Denmark)

    Parmeggiani, Stefano; Kofoed, Jens Peter

    The Wave Dragon is a floating slack-moored Wave Energy Converter (WEC) of the overtopping type. Oncoming waves are focused by two wing reflectors towards the ramp of the device, surge-up and overtop into a reservoir placed at a higher level than the surface of the sea. The energy production takes...... place as the water is led back to the sea through a set of low-head hydro-turbines. After many years of development, Wave Dragon (WD) is now facing the phase of pre-commercial demonstration. In this phase it is very important to be able to use the available data to predict the performances of the device...... at different scales and locations. A flexible and comprehensive modelling tool is therefore highly required. Wave Dragon produces power through different steps of energy conversion: 1. Primary energy conversion: overtopping – The energy content of the wave (partly in the kinetic and partly in the potential...

  16. Experiments with Point Absorber Type Wave Energy Converters in a Large-Scale Wave Basin

    DEFF Research Database (Denmark)

    Stratigaki, Vasiliki; Troch, Peter; Stallard, Tim

    2014-01-01

    Wave Energy Converters (WECs) extract energy from ocean waves and have the potential to produce a significant contribution of electricity from renewable sources. However, large "WEC farms" or "WEC arrays" are expected to have "WEC array effects", expressed as the impact of the WECs on the wave...... of geometric layout configurations and wave conditions. WEC response, wave induced forces on the WECs and wave field modifications have been measured. Each WEC consists of a buoy with diameter of 0.315 m. Power take-off is modeled by realizing friction based energy dissipation through damping of the WECs...... array effects and for validation and extension of numerical models. This model validation will enable optimization of the geometrical layout of WEC arrays for real applications and reduction of the cost of energy from wave energy systems....

  17. A New Methodology for Frequency Domain Analysis of Wave Energy Converters with Periodically Varying Physical Parameters

    Science.gov (United States)

    Mosher, Mark

    Within a wave energy converter's operational bandwidth, device operation tends to be optimal in converting mechanical energy into a more useful form at an incident wave period that is proximal to that of a power-producing mode of motion. Point absorbers, a particular classification of wave energy converters, tend to have a relative narrow optimal bandwidth. When not operating within the narrow optimal bandwidth, a point absorber's response and efficiency is attenuated. Given the wide range of sea-states that can be expected during a point absorber's operational life, these devices require a means to adjust, or control, their natural response to maximize the amount of energy absorbed in the large population of non-optimal conditions. In the field of wave energy research, there is considerable interest in the use of non-linear control techniques to this end. Non-linear control techniques introduce time-varying and state dependent control parameters into the point absorber motion equations, which usually motivates a computationally expensive numerical integration to determine the response of the device - important metrics such as gross converted power and relative travels of the device's pieces are extracted through post processing of the time series data. As an alternative, the work presented in this thesis was based on a closed form perturbation based approach for analysis of the response of a device with periodically-varying control parameters, subject to regular wave forcing, in the frequency domain. The proposed perturbation based method provides significant savings in computational time and enables the device's response to be represented in a closed form manner with a relatively small number of solution components - each component is comprised of a complex amplitude and oscillation frequency. This representation of the solution was found to be very concise and descriptive, and to lend itself to the calculation of gross absorbed power and travel constraint

  18. Development of the Second-Generation Oscillating Surge Wave Energy Converter with Variable Geometry: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Tom, Nathan M [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Yu, Yi-Hsiang [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Thresher, Robert W [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2017-07-25

    This study investigates the effect of design changes on the hydrodynamics of a novel oscillating surge wave energy converter being developed at the National Renewable Energy Laboratory. The design utilizes controllable geometry features to shed structural loads while maintaining a rated power over a greater number of sea states. The second-generation design will seek to provide a more refined control of performance because the first-generation design demonstrated performance reductions considered too large for smooth power output. Performance is evaluated using frequency domain analysis with consideration of a nonideal power-take-off system, with respect to power absorption, foundation loads, and power-take-off torque.

  19. Beach Response to Wave Energy Converter Farms Acting as Coastal Defence

    DEFF Research Database (Denmark)

    Mendoza, Edgar; Silva, Rodolfo; Zanuttigh, Barbara

    2014-01-01

    beach maintenance and coastal safety. This may be an opportunity for the multi-purpose use of Wave Energy Converters (WECs) if the foreseen increase of energy demand in coastal areas is also considered. In this paper a group of WECs based on different operating concepts is numerically tested in front...... against new experimental results. The wave field is then used as input for the analytical calculation of the long-shore sediment transport and the coastline trend is estimated by applying the continuity of sediment equation. The characteristics of the selected numerical models give this work a first...

  20. Near-Shore Floating Wave Energy Converters:applications for coastal protection

    OpenAIRE

    Ruol, Piero; Zanuttigh, Barbara; Martinelli, Luca; Kofoed, Jens Peter; Frigaard, Peter

    2010-01-01

    Aim of this note is to analyse the possible application of a Wave Energy Converter (WEC) as a combined tool to protect the coast and harvest energy. Physical model tests are used to evaluate wave transmission past a near-shore floating WEC of the wave activated body type, named DEXA. Efficiency and transmission characteristics are approximated to functions of wave height, period and obliquity. Their order of magnitude are 20% and 80%, respectively. It is imagined that an array of DEXA is depl...

  1. Investigation of Wave Transmission from a Floating Wave Dragon Wave Energy Converter

    DEFF Research Database (Denmark)

    Nørgaard, Jørgen Harck; Andersen, Thomas Lykke

    2012-01-01

    This paper focuses on the calibration of the MIKE21BW model against the measured wave height reduction behind a 24 kW/m Wave Dragon (WD) wave energy converter. A numerical model is used to determine the wave transmission through the floating WD in varying wave conditions. The transmission obtained...... from the MIKE21BW model is compared to results from a simpler model, based on the integration of wave energy flux. The conclusion is that the simplified approach provides results similar to the transmission obtained from the numerical model, both for a single WD and a farm of multiple WDs....

  2. Design of a multi-poppet on-off valve for wave energy converters

    DEFF Research Database (Denmark)

    Hansen, Anders Hedegaard; Pedersen, Henrik C.; Andersen, Torben Ole

    2013-01-01

    Fluid power systems are the leading technology for the power take off system in ocean wave energy converters. However, fluid power systems often suffer from poor efficiency, especially in part loads. This degrades the PTO system efficiency and therefore lower the energy production. To overcome...... than 15 ms. The pilot stage is directly actuated and utilises internal valve pressure as supply and an external tank connection as drain. The current article presents the design process leading to the final valve design. This includes the geometric design of the main stage, the choice of pilot valve...

  3. Estimation of Downtime and of Missed Energy Associated with a Wave Energy Converter by the Equivalent Power Storm Model

    Directory of Open Access Journals (Sweden)

    Felice Arena

    2015-10-01

    Full Text Available The design of any wave energy converter involves the determination of relevant statistical data on the wave energy resource oriented to the evaluation of the structural reliability and energy performance of the device. Currently, limited discussions concern the estimation of parameters connected to the energy performance of a device. Thus, this paper proposes a methodology for determining average downtime and average missed energy, which is the energy that is not harvested because of device deactivations during severe sea storms. These quantities are fundamental for evaluating the expected inactivity of a device during a year or during its lifetime and are relevant for assessing the effectiveness of a device working at a certain site. For this purpose, the equivalent power storm method is used for their derivation, starting from concepts pertaining to long-term statistical analysis. The paper shows that the proposed solutions provide reliable estimations via comparison with results obtained by processing long wave data.

  4. Non Isolated and Non-Inverting Cockcroft Walton Multiplier Based Hybrid 2Nx Interleaved Boost Converter For Renewable Energy Applications

    DEFF Research Database (Denmark)

    Bhaskar, Mahajan Sagar; Padamanaban, Sanjeevi Kumar; Blaabjerg, Frede

    2016-01-01

    In this paper hybrid non isolated and non-invertingCockcroft-Walton multiplier based 2Nx InterleavedBoost converter (2Nx IBC) for renewable energy applications is presented. The presented hybrid boost converter topology is derived from non-inverting Nx Multilevel Boost Converter (Nx MBC......) and inverting Nx Multilevel Boost Converter (Nx MBC). In renewable energy applications, generated voltage needs to be stepped up with high conversion ratio using a DC-DC converter at voltage levels as per the application requirement. The advantages of the presentedtopology of interleaved converter are high...... voltage conversion ratio, reduce ripple, low voltage stress, non-inverting output voltage without utilizing the high duty cycle, coupled inductors and transformer. The main advantage of presented topology consists in increasing voltage gain by adding capacitor and diode into circuitry without disturbing...

  5. Stakeholder perspectives on converting forest biomass to energy in Oregon, USA

    Energy Technology Data Exchange (ETDEWEB)

    Stidham, Melanie; Simon-Brown, Viviane [Department of Forest Ecosystems and Society, College of Forestry, Oregon State University, 321 Richardson Hall, Corvallis, OR 97331 (United States)

    2011-01-15

    Within the state of Oregon, USA, there is considerable interest in the possibility of converting forest biomass to energy. A number of studies have assessed the technical feasibility of forest biomass energy, but few have focused on social aspects, an important consideration in projects involving public forests. This study explores the social context of converting forest biomass to energy, using qualitative research methods. Semi-structured interviews were conducted with forty individuals representing nine different stakeholder groups. Information gained through interviews was used to understand stakeholder views on forest biomass energy, including their perspectives on potential barriers and opportunities in Oregon. Findings indicate the most challenging barrier will be access to long-term, consistent supply. A related challenge is the long history of contention between parties over forest products coming from public lands. However, findings also show that there are many areas of common ground between these groups that have historically been at odds, such as agreement on the necessity of restoration treatments in certain forest types, the by-product of which could be used for biomass generation. Potential conflicts still exist, for instance over projects in mixed conifer forests. Development of policies and projects through inclusive, collaborative approaches could alleviate controversies, potentially allowing more activities to move forward. Information provided by this research creates a foundation for discussions as forest biomass energy becomes an increasingly prominent issue in Oregon, the western USA, and other regions of the world. (author)

  6. Design and Analysis for a Floating Oscillating Surge Wave Energy Converter: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Y. H.; Li, Y.; Hallett, K.; Hotimsky, C.

    2014-03-01

    This paper presents a recent study on the design and analysis of an oscillating surge wave energy converter. A successful wave energy conversion design requires the balance between the design performance and cost. The cost of energy is often used as the metric to judge the design of the wave energy conversion system. It is often determined based on the device power performance, the cost for manufacturing, deployment, operation and maintenance, as well as the effort to ensure the environmental compliance. The objective of this study is to demonstrate the importance of a cost driven design strategy and how it can affect a WEC design. Three oscillating surge wave energy converter (OSWEC) designs were used as the example. The power generation performance of the design was modeled using a time-domain numerical simulation tool, and the mass properties of the design were determined based on a simple structure analysis. The results of those power performance simulations, the structure analysis and a simple economic assessment were then used to determine the cost-efficiency of selected OSWEC designs. Finally, a discussion on the environmental barrier, integrated design strategy and the key areas that need further investigation is also presented.

  7. A Methodology for Production and Cost Assessment of a Farm of Wave Energy Converters

    DEFF Research Database (Denmark)

    Beels, C.; Troch, P.; Kofoed, Jens Peter;

    2011-01-01

    the power production and cost of a farm of WECs is applied to the Wave Dragon Wave Energy Converter (WD–WEC). The WD–WEC is a floating offshore converter of the overtopping type, which captures the water volume of overtopped waves in a basin above mean sea level and produces power when the water drains back......To generate a substantial amount of power, Wave Energy Converters (WECs) are arranged in several rows or in a ‘farm’. Both the power production and cost of a farm are lay-out dependent. In this paper, the wave power redistribution in and around three farm lay-outs in a near shore North Sea wave...... climate, is assessed numerically using a time-dependent mild-slope equation model. The modelling of the wave power redistribution is an efficient tool to assess the power production of a farm. Further, for each lay-out an optimal (low cost) submarine cable network is designed. The methodology to assess...

  8. Digital computer simulation of inductor-energy-storage dc-to-dc converters with closed-loop regulators

    Science.gov (United States)

    Ohri, A. K.; Owen, H. A.; Wilson, T. G.; Rodriguez, G. E.

    1974-01-01

    The simulation of converter-controller combinations by means of a flexible digital computer program which produces output to a graphic display is discussed. The procedure is an alternative to mathematical analysis of converter systems. The types of computer programming involved in the simulation are described. Schematic diagrams, state equations, and output equations are displayed for four basic forms of inductor-energy-storage dc to dc converters. Mathematical models are developed to show the relationship of the parameters.

  9. Photovoltaic Energy Conversion System Constructed by High Step-Up Converter with Hybrid Maximum Power Point Tracking

    OpenAIRE

    Hwu, K. I.; Tu, W. C.; Wang, C.R.

    2013-01-01

    A photovoltaic energy conversion system, constructed by high step-up converter with hybrid maximum power point tracking (HMPPT), is presented. A voltage converter with a high voltage conversion ratio is proposed, which is simple in circuit and easy in control. After this, such a converter operating with a suitable initial duty cycle of the pulsewidth-modulated (PWM) control signal, together with the proposed HMPPT algorithm combining the fractional open-circuit voltage method and the incremen...

  10. Non-Linear Behavioral Modeling for DC-DC Converters and Dynamic Analysis of Distributed Energy Systems

    OpenAIRE

    Xiancheng Zheng; Husan Ali; Xiaohua Wu; Haider Zaman; Shahbaz Khan

    2017-01-01

    In modern distributed energy systems (DES), focus is shifting from the conventional centralized approach towards distributed architectures. However, modeling and analysis of these systems is more complex, as it involves the interface of multiple energy sources with many different type of loads through power electronics converters. The integration of power electronics converters allows distributed renewable energy sources to become part of modern electronics power distribution systems (EPDS). ...

  11. Theoretical studies on performance evaluation of solar thermoelectronic energy converter with graphene emitter

    Science.gov (United States)

    Olawole, Olukunle; de, Dilip

    In this paper we consider detailed energy dynamics of solar thermoelectronic energy converter using graphene as the emitter. The emitter is heated by solar energy concentrated by a parabolic mirror concentrator. We study the performance evaluation of the energy conversion using temperature dependent work function of graphene and model the space charge problem by introducing a factor in the emitter and collector current densities. We present computations on power output and efficiency as function of solar insolation, height of emitter from the base of the mirror, reflection coefficient of the mirror, temperature and work function of collector. Effect of molecular doping on the performance of the graphene solar tech is also discussed. Please schedule our papers so that they are well separated in time for presentations.

  12. FPA Tuned Fuzzy Logic Controlled Synchronous Buck Converter for a Wave/SC Energy System

    Directory of Open Access Journals (Sweden)

    SAHIN, E.

    2017-02-01

    Full Text Available This paper presents a flower pollination algorithm (FPA tuned fuzzy logic controlled (FLC synchronous buck converter (SBC for an integrated wave/ supercapacitor (SC hybrid energy system. In order to compensate the irregular wave effects on electrical side of the wave energy converter (WEC, a SC unit charged by solar panels is connected in parallel to the WEC system and a SBC is controlled to provide more reliable and stable voltage to the DC load. In order to test the performance of the designed FLC, a classical proportional-integral-derivative (PID controller is also employed. Both of the controllers are optimized by FPA which is a pretty new optimization algorithm and a well-known optimization algorithm of which particle swarm optimization (PSO to minimize the integral of time weighted absolute error (ITAE performance index. Also, the other error-based objective functions are considered. The entire energy system and controllers are developed in Matlab/Simulink and realized experimentally. Real time applications are done through DS1104 Controller Board. The simulation and experimental results show that FPA tuned fuzzy logic controller provides lower value performance indices than conventional PID controller by reducing output voltage sags and swells of the wave/SC energy system.

  13. Why Flavins Are not Competitors of Chlorophyll in the Evolution of Biological Converters of Solar Energy

    Science.gov (United States)

    Kritsky, Mikhail S.; Telegina, Taisiya A.; Vechtomova, Yulia L.; Buglak, Andrey A.

    2013-01-01

    Excited flavin molecules can photocatalyze reactions, leading to the accumulation of free energy in the products, and the data accumulated through biochemical experiments and by modeling prebiological processes suggest that flavins were available in the earliest stages of evolution. Furthermore, model experiments have shown that abiogenic flavin conjugated with a polyamino acid matrix, a pigment that photocatalyzes the phosphorylation of ADP to form ATP, could have been present in the prebiotic environment. Indeed, excited flavin molecules play key roles in many photoenzymes and regulatory photoreceptors, and the substantial structural differences between photoreceptor families indicate that evolution has repeatedly used flavins as chromophores for photoreceptor proteins. Some of these photoreceptors are equipped with a light-harvesting antenna, which transfers excitation energy to chemically reactive flavins in the reaction center. The sum of the available data suggests that evolution could have led to the formation of a flavin-based biological converter to convert light energy into energy in the form of ATP. PMID:23271372

  14. Why Flavins Are not Competitors of Chlorophyll in the Evolution of Biological Converters of Solar Energy

    Directory of Open Access Journals (Sweden)

    Mikhail S. Kritsky

    2012-12-01

    Full Text Available Excited flavin molecules can photocatalyze reactions, leading to the accumulation of free energy in the products, and the data accumulated through biochemical experiments and by modeling prebiological processes suggest that flavins were available in the earliest stages of evolution. Furthermore, model experiments have shown that abiogenic flavin conjugated with a polyamino acid matrix, a pigment that photocatalyzes the phosphorylation of ADP to form ATP, could have been present in the prebiotic environment. Indeed, excited flavin molecules play key roles in many photoenzymes and regulatory photoreceptors, and the substantial structural differences between photoreceptor families indicate that evolution has repeatedly used flavins as chromophores for photoreceptor proteins. Some of these photoreceptors are equipped with a light-harvesting antenna, which transfers excitation energy to chemically reactive flavins in the reaction center. The sum of the available data suggests that evolution could have led to the formation of a flavin-based biological converter to convert light energy into energy in the form of ATP.

  15. Consequences of converting graded to action potentials upon neural information coding and energy efficiency.

    Science.gov (United States)

    Sengupta, Biswa; Laughlin, Simon Barry; Niven, Jeremy Edward

    2014-01-01

    Information is encoded in neural circuits using both graded and action potentials, converting between them within single neurons and successive processing layers. This conversion is accompanied by information loss and a drop in energy efficiency. We investigate the biophysical causes of this loss of information and efficiency by comparing spiking neuron models, containing stochastic voltage-gated Na(+) and K(+) channels, with generator potential and graded potential models lacking voltage-gated Na(+) channels. We identify three causes of information loss in the generator potential that are the by-product of action potential generation: (1) the voltage-gated Na(+) channels necessary for action potential generation increase intrinsic noise and (2) introduce non-linearities, and (3) the finite duration of the action potential creates a 'footprint' in the generator potential that obscures incoming signals. These three processes reduce information rates by ∼50% in generator potentials, to ∼3 times that of spike trains. Both generator potentials and graded potentials consume almost an order of magnitude less energy per second than spike trains. Because of the lower information rates of generator potentials they are substantially less energy efficient than graded potentials. However, both are an order of magnitude more efficient than spike trains due to the higher energy costs and low information content of spikes, emphasizing that there is a two-fold cost of converting analogue to digital; information loss and cost inflation.

  16. Discrete Displacement Hydraulic Power Take-Off System for the Wavestar Wave Energy Converter

    Directory of Open Access Journals (Sweden)

    Enrique Vidal

    2013-08-01

    Full Text Available The Wavestar Wave Energy Converter (WEC is a multiple absorber concept, consisting of 20 hemisphere shaped floats attached to a single platform. The heart of the Wavestar WEC is the Power Take-Off (PTO system, converting the wave induced motion of the floats into a steady power output to the grid. In the present work, a PTO based on a novel discrete displacement fluid power technology is explored for the Wavestar WEC. Absorption of power from the floats is performed by hydraulic cylinders, supplying power to a common fixed pressure system with accumulators for energy smoothing. The stored pressure energy is converted into electricity at a steady pace by hydraulic motors and generators. The storage, thereby, decouples the complicated process of wave power absorption from power generation. The core for enabling this PTO technology is implementing a near loss-free force control of the energy absorbing cylinders. This is achieved by using special multi-chambered cylinders, where the different chambers may be connected to the available system pressures using fast on/off valves. Resultantly, a Discrete Displacement Cylinder (DDC is created, allowing near loss free discrete force control. This paper presents a complete PTO system for a 20 float Wavestar based on the DDC. The WEC and PTO is rigorously modeled from incident waves to the electric output to the grid. The resulting model of +600 states is simulated in different irregular seas, showing that power conversion efficiencies above 70% from input power to electrical power is achievable for all relevant sea conditions.

  17. Optimal Constant DC Link Voltage Operation of aWave Energy Converter

    Directory of Open Access Journals (Sweden)

    Mats Leijon

    2013-04-01

    Full Text Available 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.

  18. Design of Bidirectional Check Valve for Discrete Fluid Power Force System for Wave Energy Converters

    DEFF Research Database (Denmark)

    Hansen, Anders Hedegaard; Pedersen, Henrik C.; Andersen, Torben Ole

    2014-01-01

    Discrete fluid power force systems consisting of a multichamber cylinder, a witching manifold and common pressure lines have been proposed as a technology for increasing the efficiency of the power take off system in ocean wave energy converters. However the force shifting of these discrete systems...... enables passive force switching under minimal pressure difference, hence minimal energy loss. The bidirectional check valve is designed with a rated flow in the range of 1000L/min@5bar. The flow direction of the bidirectional check valve is set by the setting the pilot pressure. This paper presents...... a functionality test of a 125 L/min@5bar bidirectional check, leading to the design and modelling of a bidirectional check valve for ocean wave energy. It shows that a feasible bidirectional check valve may be configured by employing a multi-poppet topology for the main stage and utilising a 3/2 switching valve...

  19. A Predictive Power Control Strategy for DFIGs Based on a Wind Energy Converter System

    Directory of Open Access Journals (Sweden)

    Xiaoliang Yang

    2017-07-01

    Full Text Available A feasible control strategy is proposed to control a doubly fed induction generator based on the wind energy converter system (DFIG-WECS. The main aim is to enhance the steady state and dynamic performance under the condition of the parameter perturbations and external disturbances and to satisfy the stator power response of the system. Within the proposed control method, the control scheme for the rotor side converter (RSC is developed on the model predictive control. Firstly, the self-adaptive reference trajectory is established from the deduced discrete state-space equation of the generator. Then, the rotor voltage is calculated by minimizing the global performance index under the current prediction steps at the sampling instant. Through the control scheme for the grid side converter (GSC and wind turbine, we have re-applied the conventional control. The effectiveness of the proposed control strategy is verified via time domain simulation of a 150 kW-575 V DFIG-WECS using Matlab/Simulink. The simulation result shows that the control of the DFIG with the proposed control method can enhance the steady and dynamic response capability better than the conventional ones when the system faces errors due to the parameter perturbations, external disturbances and the rotor speed.

  20. Numerical comparison between deep water and intermediate water depth expressions applied to a wave energy converter

    Directory of Open Access Journals (Sweden)

    Pedro Beirão

    2015-09-01

    Full Text Available The energy that can be captured from the sea waves and converted into electricity should be seen as a contribution to decrease the excessive dependency and growing demand of fossil fuels. Devices suitable to harness this kind of renewable energy source and convert it into electricity—wave energy converters (WECs—are not yet commercially competitive. There are several types of WECs, with different designs and working principles. One possible classification is their distance to the shoreline and thus their depth. Near-shore devices are one of them since they are typically deployed at intermediate water depth (IWD. The selection of the WEC deployment site should be a balance between several parameters; water depth is one of them. Another way of classifying WECs is grouping them by their geometry, size and orientation. Considering a near-shore WEC belonging to the floating point category, this paper is focused on the numerical study about the differences arising in the power captured from the sea waves when the typical deep water (DW assumption is compared with the more realistic IWD consideration. Actually, the production of electricity will depend, among other issues, on the depth of the deployment site. The development of a dynamic model including specific equations for the usual DW assumption as well as for IWD is also described. Derived equations were used to build a time domain simulator (TDS. Numerical results were obtained by means of simulations performed using the TDS. The objective is to simulate the dynamic behavior of the WEC due to the action of sea waves and to characterize the wave power variations according with the depth of the deployment site.

  1. Mitochondria: energy converters for organization of life; Mitochondrien: Energiewandler fuer die Organisation des Lebendigen

    Energy Technology Data Exchange (ETDEWEB)

    Neupert, W. [Universitaet Muenchen (Germany). Inst. fuer Physiologische Chemie

    2004-07-01

    Maintenance and reproduction of life needs permanent supply of energy. Plants are able to convert the energy of sunlight into chemical energy. Other organisms have to take up and digest nutrients in order to generate usable forms of energy. Many types of bacteria and virtually all higher organisms use oxidation of compounds derived from nutrients as the major pathway for energy transduction. In this way, two forms of energy are produced which promote virtually all activities of animal life: First, a concentration gradient of protons across biological membranes is generated, which represents a proton motive force (PMF). In a second reaction, the energy of the PMF is stored in the molecule adenosine triphosphate (ATP), the >>universal energy coin<< for a myriad of chemical reactions within the cell. The two processes, generation of PMF powered by oxidation, and synthesis of ATP are usually coupled to each other, only for a few cellular processes PMF can be used directly. The overall reaction is called oxidative phosphorylation. It takes place in special cell organelles, the mitochondria. These small bodies are often referred to as the >>power plants of the cell<<. The term is entirely appropriate as e.g. the mitochondria of mankind generate energy of several hundred gigawatt per year. The mitochondria provide this energy to the rest of the cell. During evolution mitochondria have arisen by endosymbiosis of {alpha}-proteobacteria in precursors of the current eukaryotic cells. The bacteria brought along the enzymatic machinery of oxidative phosphorylation. The generation of the proton gradient across the inner membrane of mitochondria and the conversion of energy contained therein into energy stored in ATP are performed by a series of >>molecular machines<<. Such molecular machines are composed of a large number of different proteins and cofactors. They display amazing similarities to machines constructed by engineers in our technical world. (orig.)

  2. Balancing Power Absorption and Fatigue Loads in Irregular Waves for an Oscillating Surge Wave Energy Converter

    Energy Technology Data Exchange (ETDEWEB)

    Tom, Nathan M.; Yu, Yi-Hsiang; Wright, Alan D.; Lawson, Michael

    2016-06-24

    The aim of this paper is to describe how to control the power-to-load ratio of a novel wave energy converter (WEC) in irregular waves. The novel WEC that is being developed at the National Renewable Energy Laboratory combines an oscillating surge wave energy converter (OSWEC) with control surfaces as part of the structure; however, this work only considers one fixed geometric configuration. This work extends the optimal control problem so as to not solely maximize the time-averaged power, but to also consider the power-take-off (PTO) torque and foundation forces that arise because of WEC motion. The objective function of the controller will include competing terms that force the controller to balance power capture with structural loading. Separate penalty weights were placed on the surge-foundation force and PTO torque magnitude, which allows the controller to be tuned to emphasize either power absorption or load shedding. Results of this study found that, with proper selection of penalty weights, gains in time-averaged power would exceed the gains in structural loading while minimizing the reactive power requirement.

  3. Experimental Investigation of Irregular Wave Cancellation Using a Cycloidal Wave Energy Converter

    Science.gov (United States)

    2012-07-01

    CycWEC consists of one or more hydrofoils attached equidistant to a shaft that is aligned parallel to the incoming waves. The entire device is fully sub...300 scale wave tunnel experiment. A CycWEC consists of one or more hydrofoils attached equidistant to a shaft that is aligned parallel to the incoming...Prescribed by ANSI Std Z39-18 g Gravity constant, 9.81[m/s2] t Time [s] λ Wavelength [m] R = 60mm Wave Energy Converter Radius [m] c = 50mm Hydrofoil Chord

  4. The Inter Facility Testing of a Standard Oscillating Water Column (OWC) Type Wave Energy Converter (WEC)

    DEFF Research Database (Denmark)

    Andersen, Morten Thøtt; Thomsen, Jonas Bjerg

    This report describes the behavior and preliminary performance of a simplified standard oscillating water column (OWC) wave energy converter (WEC). The same tests will be conducted at different scales at 6 different test facilities and the results obtained will be used for comparison. This projec...... at Aalborg University, Sohngaardsholmsvej 57, DK-9000 Aalborg. For further information regarding the content of this report please contact Morten Thøtt Andersen (mta@civil.aau.dk) or Jonas Bjerg Thomsen (jbt@civil.aau.dk) from the Department of Civil Engineering....

  5. Report of the DOD-DOE Workshop on Converting Waste to Energy Using Fuel Cells

    Science.gov (United States)

    2011-10-01

    per day into clean methane gas. This waste is now a source of fuel for a 600-kilowatt (kW) solid oxide fuel cell system that provides power and...assets/documents/2009fedleader_eo_rel.pdf. Page 3 DOD-DOE Workshop Summary on Converting Waste to Energy Using Fuel Cells F igure 1. W orks...for both at current costs, when federal and state incentives are available • The integration of stationary fuel cells with biomass gasification is a

  6. Model Testing of the Wave Energy Converter Seawave Slot-Cone Generator

    DEFF Research Database (Denmark)

    Kofoed, Jens Peter

    This report presents the results of a preliminary experimental study of the wave energy convert (WEC) Seawave Slot-Cone Generator (SSG). SSG is a WEC utilizing wave overtopping in multiple reservoirs. In the present SSG setup three reservoirs has been used. Model tests have been performed using...... a scale model (length scale 1:15) of a SSG device to be installed on the west coast of the island Kvitsøy near Stavanger, Norway. The tests were carried out at Dept. of Civil Engineering, Aalborg University (AAU) in the 3D deep water wave tank. The model has been subjected to regular and irregular waves...

  7. Experimental Modeling of the Overtopping Flow on the Wave Dragon Wave Energy Converter

    DEFF Research Database (Denmark)

    Parmeggiani, Stefano; Kofoed, Jens Peter; Friis-Madsen, Erik

    2011-01-01

    The Wave Dragon Wave Energy Converter is currently facing a precommercial phase. At this stage of development a reliable overtopping model is highly required, in order to predict the performance of the device at possible deployment locations. A model formulation derived for an overtopping device...... with general geometry has been used so far. The paper presents an updated formulation drawn through the tank testing of a scaled model the Wave Dragon. The sensitivity analysis of the main features influencing the overtopping flow led to an updated model formulation which can be specifically suited...... for the Wave Dragon....

  8. Survivability mode and extreme loads on the mooring lines of the Wave Dragon Wave Energy Converter

    Energy Technology Data Exchange (ETDEWEB)

    Parmeggiani, S.; Kofoed, J.P.

    2010-11-15

    This report is a product of the cooperation agreement between Wave Dragon and Aalborg University regarding phase 2 of the development of the Wave Dragon Wave Energy Converter. The research is carried out by testing the 1:51.8 scale model of the Wave Dragon, aiming at the assessment of the survivability of the device in extreme waves and evaluation of the design loads for the mooring component. The outcome of the research will be used as input for future research work aimed at the design of the mooring system and the certification of the structural design for the full scale Wave Dragon demonstrator. (Author)

  9. Analysis of Wave Reflection from Wave Energy Converters Installed as Breakwaters in Harbour

    DEFF Research Database (Denmark)

    Zanuttigh, B.; Margheritini, Lucia; Gambles, L.

    2009-01-01

    Amplification and renovation of harbours, none the last for the need of straitening existing structures because of the increased storminess due to climate change, is a practice that is repeating itself all around the world. To this purpose, integration of breakwaters and Wave Energy Converters...... (WECs) based on two different technologies, one based on the overtopping principle and the other of Oscillating Water Column (OWC) type, revealed to be suitable with different advantages compared to offshore installations, among the others: sharing of costs, cheaper accessibility and maintenance, lower...

  10. Experimental Modeling of the Overtopping Flow on the Wave Dragon Wave Energy Converter

    DEFF Research Database (Denmark)

    Parmeggiani, Stefano; Kofoed, Jens Peter; Friis-Madsen, Erik

    2011-01-01

    The Wave Dragon Wave Energy Converter is currently facing a precommercial phase. At this stage of development a reliable overtopping model is highly required, in order to predict the performance of the device at possible deployment locations. A model formulation derived for an overtopping device...... with general geometry has been used so far. The paper presents an updated formulation drawn through the tank testing of a scaled model the Wave Dragon. The sensitivity analysis of the main features influencing the overtopping flow led to an updated model formulation which can be specifically suited...... for the Wave Dragon....

  11. Power maximization of a point absorber wave energy converter using improved model predictive control

    Science.gov (United States)

    Milani, Farideh; Moghaddam, Reihaneh Kardehi

    2017-08-01

    This paper considers controlling and maximizing the absorbed power of wave energy converters for irregular waves. With respect to physical constraints of the system, a model predictive control is applied. Irregular waves' behavior is predicted by Kalman filter method. Owing to the great influence of controller parameters on the absorbed power, these parameters are optimized by imperialist competitive algorithm. The results illustrate the method's efficiency in maximizing the extracted power in the presence of unknown excitation force which should be predicted by Kalman filter.

  12. Design and Fabrication of a Micro Electrostatic Vibration-to-Electricity Energy Converter

    CERN Document Server

    Chiu, Yi; Chu, Yu-Shan

    2007-01-01

    This paper presents a micro electrostatic vibration-toelectricity energy converter. For the 3.3 V supply voltage and 1cm2 chip area constraints, optimal design parameters were found from theoretical calculation and Simulink simulation. In the current design, the output power is 200 $\\mu$W/cm2 for the optimal load of 8 M\\Omega. The device was fabricated in a silicon-on-insulator (SOI) wafer. Mechanical and electrical measurements were conducted. Residual particles caused shortage of the variable capacitor and the output power could not be measured. Device design and fabrication processes are being refined.

  13. Comparison and Sensitivity Investigations of a CALM and SALM Type Mooring System for Wave Energy Converters

    OpenAIRE

    Arthur Pecher; Aligi Foglia; Jens Peter Kofoed

    2014-01-01

    A quasi-static analysis and sensitivity investigation of two different mooring configurations—a single anchor leg mooring (SALM) and a three-legged catenary anchor leg system (CALM)—is presented. The analysis aims to indicate what can be expected in terms of requirements for the mooring system size and stiffness. The two mooring systems were designed for the same reference load case, corresponding to a horizontal design load at the wave energy converter (WEC) of 2000 kN and a water depth of 3...

  14. Cost, Time, and Risk Assessment of Different Wave Energy Converter Technology Development Trajectories: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Weber, Jochem W [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Laird, Daniel [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Costello, Ronan [Wave Venture; Roberts, Jesse [Sandia National Laboratories; Bull, Diana [Sandia National Laboratories; Babarit, Aurelien [Ecole Centrale de Nantes; Nielsen, Kim [Ramboll; Ferreira, Claudio Bittencourt [DNV-GL; Kennedy, Ben [Wave Venture

    2017-09-14

    This paper presents a comparative assessment of three fundamentally different wave energy converter technology development trajectories. The three technology development trajectories are expressed and visualised as a function of technology readiness levels and technology performance levels. The assessment shows that development trajectories that initially prioritize technology readiness over technology performance are likely to require twice the development time, consume a threefold of the development cost, and are prone to a risk of technical or commercial failure of one order of magnitude higher than those development trajectories that initially prioritize technology performance over technology readiness.

  15. Utilization of transparent heat-reflecting coatings in solar-energy converters. [ZnS--Ag--ZnS

    Energy Technology Data Exchange (ETDEWEB)

    Koltun, M.N.; Faiziev, Sh.A.

    1977-01-01

    The optical characteristics of dielectric-metal-dielectric coatings developed by the authors on glass and polymer films are described. The possibility of using ZnS--Ag--ZnS coatings in solar-energy converters is considered.

  16. A tapped-inductor buck-boost converter for a multi-DEAP generator energy harvesting system

    DEFF Research Database (Denmark)

    Dimopoulos, Emmanouil; Munk-Nielsen, Stig

    2014-01-01

    the effective operational range of the power electronic converter. In this paper, a bidirectional tapped-inductor buck-boost converter is proposed, addressing high-efficient high step-up and high step-down voltage conversion ratios, for energy harvesting applications based on DEAP generators. The effective...... operational range of the converter is extended, by replacing its high-side switch with a string of three serialized MOSFETs, to accommodate the need for high-efficient high-voltage operation. Experiments conducted on a single DEAP generator - part of a quadruple DEAP generator energy harvesting system...... with all elements installed sequentially in the same circular disk with a 90 phase shift - validate the applicability of the proposed converter, demonstrating energy harvesting of 0.26 J, at 0.5 Hz and 60 % delta-strain; characterized by an energy density of 1.25 J per kg of active material....

  17. Fractional-order control and simulation of wind energy systems with PMSG/full-power converter topology

    Energy Technology Data Exchange (ETDEWEB)

    Melicio, R.; Catalao, J.P.S. [Department of Electromechanical Engineering, University of Beira Interior, R. Fonte do Lameiro, 6201-001 Covilha (Portugal); Mendes, V.M.F. [Department of Electrical Engineering and Automation, Instituto Superior de Engenharia de Lisboa, R. Conselheiro Emidio Navarro, 1950-062 Lisbon (Portugal)

    2010-06-15

    This paper presents a new integrated model for the simulation of wind energy systems. The proposed model is more realistic and accurate, considering a variable-speed wind turbine, two-mass rotor, permanent magnet synchronous generator (PMSG), different power converter topologies, and filters. Additionally, a new control strategy is proposed for the variable-speed operation of wind turbines with PMSG/full-power converter topology, based on fractional-order controllers. Comprehensive simulation studies are carried out with matrix and multilevel power converter topologies, in order to adequately assert the system performance in what regards the quality of the energy injected into the electric grid. Finally, conclusions are duly drawn. (author)

  18. Modelling of the Overtopping Flow on the Wave Dragon Wave Energy Converter

    DEFF Research Database (Denmark)

    Parmeggiani, Stefano; Pecher, Arthur; Kofoed, Jens Peter

    2010-01-01

    The Wave Dragon is a floating slack-moored Wave Energy Converter of the overtopping type, which is facing now the last phase of development before the commercial exploitation: the deployment of a full-scale demonstrator. In this phase a modelling tool allowing for accurate predictions of the perf......The Wave Dragon is a floating slack-moored Wave Energy Converter of the overtopping type, which is facing now the last phase of development before the commercial exploitation: the deployment of a full-scale demonstrator. In this phase a modelling tool allowing for accurate predictions...... of the performance of the device at different scaling ratios and locations of interest is strongly required. The overtopping, depending on the local conditions of the deployment site, is identified as the right stage to be considered in the modelling. The existing formulation of the overtopping model needs...... to be updated in order to represent more accurately the effects of the geometrical features and stability of the device and of the local conditions and nonscalable parameters on the overtopping flow. The paper analyses the conditions at which the present formulation has been established and proposes a strategy...

  19. Development of a nearshore oscillating surge wave energy converter with variable geometry

    Energy Technology Data Exchange (ETDEWEB)

    Tom, N. M. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Lawson, M. J. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Yu, Y. H. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Wright, A. D. [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2016-10-01

    This paper presents an analysis of a novel wave energy converter concept that combines an oscillating surge wave energy converter (OSWEC) with control surfaces. The control surfaces allow for a variable device geometry that enables the hydrodynamic properties to be adapted with respect to structural loading, absorption range and power-take-off capability. The device geometry is adjusted on a sea state-to-sea state time scale and combined with wave-to-wave manipulation of the power take-off (PTO) to provide greater control over the capture efficiency, capacity factor, and design loads. This work begins with a sensitivity study of the hydrodynamic coefficients with respect to device width, support structure thickness, and geometry. A linear frequency domain analysis is used to evaluate device performance in terms of absorbed power, foundation loads, and PTO torque. Previous OSWEC studies included nonlinear hydrodynamics, in response a nonlinear model that includes a quadratic viscous damping torque that was linearized via the Lorentz linearization. Inclusion of the quadratic viscous torque led to construction of an optimization problem that incorporated motion and PTO constraints. Results from this study found that, when transitioning from moderate-to-large sea states the novel OSWEC was capable of reducing structural loads while providing a near constant power output.

  20. Model Based Optimization of Integrated Low Voltage DC-DC Converter for Energy Harvesting Applications

    Science.gov (United States)

    Jayaweera, H. M. P. C.; Muhtaroğlu, Ali

    2016-11-01

    A novel model based methodology is presented to determine optimal device parameters for the fully integrated ultra low voltage DC-DC converter for energy harvesting applications. The proposed model feasibly contributes to determine the maximum efficient number of charge pump stages to fulfill the voltage requirement of the energy harvester application. The proposed DC-DC converter based power consumption model enables the analytical derivation of the charge pump efficiency when utilized simultaneously with the known LC tank oscillator behavior under resonant conditions, and voltage step up characteristics of the cross-coupled charge pump topology. The verification of the model has been done using a circuit simulator. The optimized system through the established model achieves more than 40% maximum efficiency yielding 0.45 V output with single stage, 0.75 V output with two stages, and 0.9 V with three stages for 2.5 kΩ, 3.5 kΩ and 5 kΩ loads respectively using 0.2 V input.

  1. Critical Factors Influencing Viability of Wave Energy Converters in Off-Grid Luxury Resorts and Small Utilities

    Directory of Open Access Journals (Sweden)

    Aksel Botne Sandberg

    2016-12-01

    Full Text Available This paper examines technical and non-technical factors that are critical to the viability of commercialization of wave energy converters in off-grid luxury resorts and small utilities. Critical factors are found by investigating Levelized Cost of Energy, and using the tools PESTEL and Porter’s five competitive forces. Identified factors are then applied on three business cases to investigate their impact on viability. The results show that one of the main challenges facing off-grid commercialization is the few wave energy converter units installed per location, negating the economy of scale that large wave energy farms count on to achieve competitive cost levels. In addition, factors like current cost of energy, available wave resources, distance from shore, infrastructure, supply chain logistics, and electricity demand are found to be deciding factors for viability. Despite these challenges, it is found that there are potentially viable off-grid business cases for commercialization of wave energy converters.

  2. Converting Limbo Lands to Energy-Generating Stations: Renewable Energy Technologies on Underused, Formerly Contaminated Sites

    Energy Technology Data Exchange (ETDEWEB)

    Mosey, G.; Heimiller, D.; Dahle, D.; Vimmerstedt, L.; Brady-Sabeff, L.

    2007-10-01

    This report addresses the potential for using 'Limbo Lands' (underused, formerly contaminated sites, landfills, brownfields, abandoned mine lands, etc. ) as sites for renewable energy generating stations.

  3. A review of hydrodynamic investigations into arrays of ocean wave energy converters

    CERN Document Server

    De Chowdhury, S; Sanchez, A Madrigal; Fleming, A; Winship, B; Illesinghe, S; Toffoli, A; Babanin, A; Penesis, I; Manasseh, R

    2015-01-01

    Theoretical, numerical and experimental studies on arrays of ocean wave energy converter are reviewed. The importance of extracting wave power via an array as opposed to individual wave-power machines has long been established. There is ongoing interest in implementing key technologies at commercial scale owing to the recent acceleration in demand for renewable energy. To date, several reviews have been published on the science and technology of harnessing ocean-wave power. However, there have been few reviews of the extensive literature on ocean wave-power arrays. Research into the hydrodynamic modelling of ocean wave-power arrays is analysed. Where ever possible, comparisons are drawn with physical scaled experiments. Some critical knowledge gaps have been found. Specific emphasis has been paid on understanding how the modelling and scaled experiments are likely to be complementary to each other.

  4. Wave Energy Converter (WEC) Array Effects on Wave Current and Sediment Circulation: Monterey Bay CA.

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, Jesse D.; Jones, Craig; Magalen, Jason

    2014-09-01

    The goal s of this study were to develop tools to quantitatively characterize environments where wave energy converter ( WEC ) devices may be installed and to assess e ffects on hydrodynamics and lo cal sediment transport. A large hypothetical WEC array was investigated using wave, hydrodynamic, and sediment transport models and site - specific average and storm conditions as input. The results indicated that there were significant changes in sediment s izes adjacent to and in the lee of the WEC array due to reduced wave energy. The circulation in the lee of the array was also altered; more intense onshore currents were generated in the lee of the WECs . In general, the storm case and the average case show ed the same qualitative patterns suggesting that these trends would be maintained throughout the year. The framework developed here can be used to design more efficient arrays while minimizing impacts on nearshore environmen ts.

  5. On the Effects of Geometry Control on the Performance of Overtopping Wave Energy Converters

    DEFF Research Database (Denmark)

    Victor, Lander; Troch, Peter; Kofoed, Jens Peter

    2011-01-01

    Overtopping wave energy converters (OWECs) are designed to extract energy from ocean waves based on wave overtopping into a reservoir, which is emptied into the ocean through a set of low-head turbines, and typically feature a low crest freeboard and a smooth impermeable steep slope. In the process...... of optimizing the performance of OWECs, the question arises whether adapting the slope geometry to the variable wave characteristics at the deployment site (i.e., geometry control) can increase the overall hydraulic efficiency and overall hydraulic power compared to a fixed slope geometry. The effect of five...... different geometry control scenarios on the overall hydraulic efficiency and overall hydraulic power of OWECs has been simulated for three possible deployment sites using empirical prediction formulae. The results show that the effect of an adaptive slope angle is relatively small. On the other hand...

  6. Measurements of Overtopping Flow Time Series on the Wave Dragon, Wave Energy Converter

    DEFF Research Database (Denmark)

    Tedd, James; Kofoed, Jens Peter

    2009-01-01

    A study of overtopping flow series on the Wave Dragon prototype, a low crested device designed to maximise flow, in a real sea, is presented. This study aims to fill the gap in the literature on time series of flow overtopping low crested structures. By comparing to a simulated flow the character......A study of overtopping flow series on the Wave Dragon prototype, a low crested device designed to maximise flow, in a real sea, is presented. This study aims to fill the gap in the literature on time series of flow overtopping low crested structures. By comparing to a simulated flow...... the characteristics of the overtopping flow are discussed and the simulation algorithm is tested. Measured data is shown from a storm build up in October 2006, from theWave Dragon prototype situated in an inland sea in Northern Denmark. This wave energy converter extracts energy from the waves, by funnelling them...

  7. R&D Towards Commercialization of Sea Wave Slot Cone Generator (SSG) Overtopping Wave Energy Converter

    DEFF Research Database (Denmark)

    Margheritini, Lucia

    a fruitful decade. Improvement of technologies together with financial support at different levels gave space to new ideas, bringing the research to gamble on different concepts. While innumerable projects went through an initial testing phase that lasts 5-10 years, only few of them reached the sea prototype...... between ventures and private investors, and to promote an accelerated shift from a technology to a market focus. This Thesis is presented as a collection of works published by the author on her research on the Sea wave Slot cone Generator wave energy converter. These include 1 accepted and 2 submitted...... journal papers; 7 peer-reviewed conference papers. The results are based on laboratory tests, numerical simulations and feasibility studies. Research presented in this Thesis contributes to reduce the technical and non-technical risks associated to the wave energy sector and promotes accelerated shift...

  8. Apparatus and method for heat-run test on high-power PWM converters with low energy expenditure

    Indian Academy of Sciences (India)

    J S Siva Prasad; G Narayanan

    2013-06-01

    Before installation, a voltage source converter is usually subjected to heat-run test to verify its thermal design and performance under load. For heat-run test, the converter needs to be operated at rated voltage and rated current for a substantial length of time. Hence, such tests consume huge amount of energy in case of high-power converters. Also, the capacities of the source and loads available in the research and development (R & D) centre or the production facility could be inadequate to conduct such tests. This paper proposes a method to conduct heat-run tests on highpower, pulse width modulated (PWM) converters with low energy consumption. The experimental set-up consists of the converter under test and another converter (of similar or higher rating), both connected in parallel on the ac side and open on the dc side. Vector-control or synchronous reference frame control is employed to control the converters such that one draws certain amount of reactive power and the other supplies the same; only the system losses are drawn from the mains. The performance of the controller is validated through simulation and experiments. Experimental results, pertaining to heat-run tests on a high-power PWM converter, are presented at power levels of 25 kVA to 150 kVA.

  9. Influence of material selection on the structural behavior of a wave energy converter

    Directory of Open Access Journals (Sweden)

    Cândida M. S. P. Malça

    2014-09-01

    Full Text Available In the last decades, the world energy demand has raised significantly. Concerning this fact, wave energy should be considered as a valid alternative for electricity production. Devices suitable to harness this kind of renewable energy source and convert it into electricity are not yet commercially competitive. This paper is focused on the selection and analysis of different types of elastic materials and their influence on the structural behavior of a wave energy converter (WEC. After a brief characterization of the device, a tridimensional computer aided design (3D CAD numerical model was built and several finite element analyses (FEA were performed through a commercial finite element code. The main components of the WEC, namely the buoy, supporting cables and hydraulic cylinder were simulated assuming different materials. The software used needs, among other parameters, the magnitude of the resultant hydrodynamic forces acting upon the floating buoy obtained from a WEC time domain simulator (TDS which was built based on the WEC dynamic model previously developed. The Von Mises stress gradients and displacement fields determined by the FEA demonstrated that, regardless of the WEC component, the materials with low Young's modulus seems to be unsuitable for this kind of application. The same is valid for the material yield strength since materials with a higher yield strength lead to a better structural behavior of WEC components because lower stress and displacement values were obtained. The developed 3D CAD numerical model showed to be suitable to analyze different combinations of structural conditions. They could depend of different combinations of buoy position and resultant hydrodynamic forces acting upon the buoy, function of the specific sea wave parameters found on the deployment site.

  10. Analytical Comparison of Dual-Input Isolated dc-dc Converter with an ac or dc Inductor for Renewable Energy Systems

    DEFF Research Database (Denmark)

    Zhang, Zhe; Mira Albert, Maria del Carmen; Andersen, Michael A. E.

    2017-01-01

    This paper presents two configurations of dualinput (DI) or three-port (TPC) isolated dc-dc converters for hybrid renewable energy systems such as photovoltaics and batteries. These two converters are derived by integrating an interleaved boost converter and a single-active bridge converter...

  11. Experimental Modelling of the Overtopping Flow on the Wave Dragon Wave Energy Converter

    DEFF Research Database (Denmark)

    Parmeggiani, Stefano; Kofoed, Jens Peter

    The Wave Dragon is a floating slack-moored Wave Energy Converter (WEC) of the overtopping type. Oncoming waves are focused by two wing reflectors towards the ramp of the device, surge-up and overtop into a reservoir placed at a higher level than the surface of the sea. The energy production takes...... place as the water is led back to the sea through a set of low-head hydro-turbines. After many years of development, Wave Dragon (WD) is now facing the phase of pre-commercial demonstration. In this phase it is very important to be able to use the available data to predict the performances of the device...... form) is transferred to the device in the form of volumes of water coming into the reservoir. These volumes are stored at a higher level than the surrounding sea, being a stock of potential energy. 2. Secondary energy conversion: turbines – The potential energy stored in the reservoir is transformed...

  12. Characterization and Scaling of Heave Plates for Ocean Wave Energy Converters

    Science.gov (United States)

    Rosenberg, Brian; Mundon, Timothy

    2016-11-01

    Ocean waves present a tremendous, untapped source of renewable energy, capable of providing half of global electricity demand by 2040. Devices developed to extract this energy are known as wave energy converters (WECs) and encompass a wide range of designs. A somewhat common archetype is a two-body point-absorber, in which a surface float reacts against a submerged "heave" plate to extract energy. Newer WEC's are using increasingly complex geometries for the submerged plate and an emerging challenge in creating low-order models lies in accurately determining the hydrodynamic coefficients (added mass and drag) in the corresponding oscillatory flow regime. Here we present experiments in which a laboratory-scale heave plate is sinusoidally forced in translation (heave) and rotation (pitch) to characterize the hydrodynamic coefficients as functions of the two governing nondimensional parameters, Keulegan-Carpenter number (amplitude) and Reynolds number. Comparisons against CFD simulations are offered. As laboratory-scale physical model tests remain the standard for testing wave energy devices, effects and implications of scaling (with respect to a full-scale device) are also investigated.

  13. A novel design of DC-AC electrical machine rotary converter for hybrid solar and wind energy applications

    Science.gov (United States)

    Mohammed, K. G.; Ramli, A. Q.; Amirulddin, U. A. U.

    2013-06-01

    This paper proposes the design of a new bi-directional DC-AC rotary converter machine to convert a d.c. voltage to three-phase voltage and vice-versa using a two-stage energy conversion machine. The rotary converter consists of two main stages which are combined into single frame. These two stages are constructed from three main electromagnetic components. The first inner electromagnetic component represents the input stage that enables the DC power generated by solar energy from photo-voltaic cells to be transformed by the second and third components electro-magnetically to produce multi-phase voltages at the output stage. At the same time, extra kinetic energy from wind, which is sufficiently available, can be added to existing torque on the second electromagnetic component. Both of these input energies will add up to the final energy generated at the output terminals. Therefore, the machine will be able to convert solar and wind energies to the output terminals simultaneously. If the solar energy is low, the available wind energy will be able to provide energy to the output terminals and at the same time charges the batteries which are connected as backup system. At this moment, the machine behaves as wind turbine. The energy output from the machine benefits from two energy sources which are solar and wind. At night when the solar energy is not available and also the load is low, the wind energy is able to charge the batteries and at the same time provides output electrical power to the remaining the load. Therefore, the proposed system will have high usage of available renewable energy as compared to separated wind or solar systems. MATLAB codes are used to calculate the required dimensions, the magnetic and electrical circuits parameters to design of the new bi-directional rotary converter machine.

  14. A Novel Dual-input Isolated Current-Fed DC-DC Converter for Renewable Energy System

    DEFF Research Database (Denmark)

    Zhang, Zhe; Thomsen, Ole Cornelius; Andersen, Michael A. E.

    2010-01-01

    In this paper, a novel isolated current-fed DC-DC converter (boost-type) with two input power sources based on multi-transformer structure, which is suitable for fuel cells and super-capacitors hybrid energy system, is proposed and designed. With particular transformer windings connection strategy......, the proposed converter can draw power from two different DC sources with lower voltage and deliver it to the higher voltage DC bus or load individually and simultaneously. The detailed operation principle of the proposed converter has been analyzed in dual-input mode and single-input mode, respectively....... Furthermore, the method to increase the number of input ports, the magnetic integration structure, and ground loop decoupling are discussed. Experimental results from the lab prototype converter with two DC voltage sources verify the validity of the theoretical analysis and design of the converter....

  15. Optimum Peak Current Hysteresis Control for Energy Recovering Converter in CDI Desalination

    Directory of Open Access Journals (Sweden)

    Alberto M. Pernía

    2014-06-01

    Full Text Available Capacitive De-Ionization (CDI is becoming a suitable alternative for desalination. The low cost of the materials required and its reduced energy consumption can be critical factors for developing this technique. CDI technology does not require a high-pressure system and the energy storage capability of CDI cells allows it to be reused in other CDI cells, thus minimizing consumption. The goal of the power stage responsible of the energy recovery is transferring the stored energy from one cell to another with the maximum possible efficiency, thus allowing the desalination process to continue. Assuming hysteresis current control is implemented at the DC/DC (direct current converter, this paper aims to determine the optimum peak current through the inductor in each switching period with a view to maximizing overall efficiency. The geometrical parameters of the desalination cell and the NaCl concentration modify the cell electrical properties. The peak current control of the power stage should be adapted to the cell characteristics so that the efficiency behavior of the whole CDI system can be improved. The mathematical model defined in this paper allows the CDI plant automation using the peak inductor current as control variable, adapting its value to the salt concentration during the desalination process.

  16. Wave Protection Effect of Periodic Row of Bottom-Hinged Flap-Type Wave Energy Converters

    Institute of Scientific and Technical Information of China (English)

    王冬姣; 邱守强; 叶家玮; 梁富琳

    2016-01-01

    A flap-type wave energy converter(WEC) is combined with a nearshore breakwater to expand the ap-plication of WECs both economically and environmentally. Based on the linear potential theory, an eigenfunction expansion solution is developed for a periodic row of bottom-hinged flap-type WECs exposed to normal waves. Additionally, the viscous effect is considered using the ship rolling solution method with a viscous damping term included in the equation of motion, and the viscous damping expression is also described. The proposed solution is verified by comparison with published literatures. The results including the wave energy conversion efficiency, the reflected and transmitted proportion of the incident wave energy are presented for a range of wave periods and geometric ratios. It is demonstrated that better wave protection effects can be attained with smaller gaps between the WECs, where the transmitted proportion of the incident wave energy is lower. An optimal geometric ratio thus exists for a given wave power absorption and a specific wave period.

  17. Wind Energy Conversion System with Boost Converter and CHB MLI with single DC input

    Directory of Open Access Journals (Sweden)

    Porselvi T

    2014-03-01

    Full Text Available The developments in power electronics technology have led to the developments in the wind energy conversion system (WECS. The output voltage of the WECS depends on the speed of the wind, which is not constant. Hence, a power conversion unit is required to maintain the output voltage of the WECS constant. This paper presents the design of a boost converter and a voltage controller for maintaining the DC-link voltage of the system constant. A new topology of the cascaded H-bridge multilevel inverter (CHB MLI is proposed for the DC/ AC conversion. The proposed topology eliminates the requirement of separate DC sources. The multilevel inverter is controlled by the selective harmonic elimination pulse width modulation (SHE-PWM technique. The system is simulated in MATLAB/ Simulink for varying wind speeds. The simulated waveforms of the PMSG rotor speed, the PMSG voltage, the boost converter voltage and the CHBMLI voltages are shown and the results obtained are found to be satisfactory.

  18. The Effect of Angiotensin-Converting Enzyme Inhibition Using Captopril on Energy Balance and Glucose Homeostasis

    Science.gov (United States)

    de Kloet, Annette D.; Krause, Eric G.; Kim, Dong-Hoon; Sakai, Randall R.; Seeley, Randy J.; Woods, Stephen C.

    2009-01-01

    Increasing evidence suggests that the renin-angiotensin-system contributes to the etiology of obesity. To evaluate the role of the renin-angiotensin-system in energy and glucose homeostasis, we examined body weight and composition, food intake, and glucose tolerance in rats given the angiotensin-converting enzyme inhibitor, captopril (∼40 mg/kg · d). Rats given captopril weighed less than controls when fed a high-fat diet (369.3 ± 8.0 vs. 441.7 ± 8.5 g after 35 d; P captopril ate significantly less [3110.3 ± 57.8 vs. 3592.4 ± 88.8 kcal (cumulative 35 d high fat diet intake); P captopril caused animals to defend a lower body weight, animals in both groups were fasted for 24 h and subsequently restricted to 20% of their intake for 2 d. When free food was returned, captopril and control rats returned to their respective body weights and elicited comparable hyperphagic responses. These results suggest that angiotensin-converting enzyme inhibition protects against the development of diet-induced obesity and glucose intolerance. PMID:19497971

  19. Experimental Validation of a Theory for a Variable Resonant Frequency Wave Energy Converter (VRFWEC)

    Science.gov (United States)

    Park, Minok; Virey, Louis; Chen, Zhongfei; Mäkiharju, Simo

    2016-11-01

    A point absorber wave energy converter designed to adapt to changes in wave frequency and be highly resilient to harsh conditions, was tested in a wave tank for wave periods from 0.8 s to 2.5 s. The VRFWEC consists of a closed cylindrical floater containing an internal mass moving vertically and connected to the floater through a spring system. The internal mass and equivalent spring constant are adjustable and enable to match the resonance frequency of the device to the exciting wave frequency, hence optimizing the performance. In a full scale device, a Permanent Magnet Linear Generator will convert the relative motion between the internal mass and the floater into electricity. For a PMLG as described in Yeung et al. (OMAE2012), the electromagnetic force proved to cause dominantly linear damping. Thus, for the present preliminary study it was possible to replace the generator with a linear damper. While the full scale device with 2.2 m diameter is expected to generate O(50 kW), the prototype could generate O(1 W). For the initial experiments the prototype was restricted to heave motion and data compared to predictions from a newly developed theoretical model (Chen, 2016).

  20. A Novel Dual-input Isolated Current-Fed DC-DC Converter for Renewable Energy System

    DEFF Research Database (Denmark)

    Zhang, Zhe; Thomsen, Ole Cornelius; Andersen, Michael A. E.

    2010-01-01

    In this paper, a novel isolated current-fed DC-DC converter (boost-type) with two input power sources based on multi-transformer structure, which is suitable for fuel cells and super-capacitors hybrid energy system, is proposed and designed. With particular transformer windings connection strategy......, the proposed converter can draw power from two different DC sources with lower voltage and deliver it to the higher voltage DC bus or load individually and simultaneously. The detailed operation principle of the proposed converter has been analyzed in dual-input mode and single-input mode, respectively...

  1. Fatigue reliability and calibration of fatigue design factors of wave energy converters

    DEFF Research Database (Denmark)

    Ambühl, Simon; Ferri, Francesco; Kofoed, Jens Peter

    2015-01-01

    Target reliability levels, which are chosen dependent on the consequences in case of structural collapse, are used in this paper to calibrate partial safety factors for structural details of wave energy converters (WECs). The consequences in case of structural failure are similar for WECs...... and offshore wind turbines (no fatalities, low environmental pollution). Therefore, it can be assumed that the target reliability levels for WEC applications can be overtaken from offshore wind turbine studies. The partial safety factors cannot be directly overtaken from offshore wind turbines because the load...... is considered in order to extend and maintain a certain target safety level. This paper uses the Wavestar prototype located at Hanstholm (DK) as case study in order to calibrate FDFs for welded and bolted details in steel structures of an offshore bottom-fixed WEC with hydraulic floaters....

  2. Effects of Mooring Systems on the Performance of a Wave Activated Body Energy Converter

    DEFF Research Database (Denmark)

    Zanuttigh, Barbara; Angelelli, Elisa; Kofoed, Jens Peter

    2013-01-01

    Aim of this paper is to analyse the power and hydraulic performance of a floating Wave Energy Converter with the purpose at optimising its design for installation in arrays. The paper presents new experiments carried out in 1:30 scale on a single device of the Wave Activated Body type in the deep......-water wave tank at Aalborg University. Power production and wave transmission were examined by changing the mooring system, the wave attack and the device orientation with respect to the incoming waves.. To assure the best performance the device size may be “tuned” based on the local peak wave length...... and the mooring system should be selected to allow the device for large movements....

  3. Numerical Time Integration Methods for a Point Absorber Wave Energy Converter

    DEFF Research Database (Denmark)

    Zurkinden, Andrew Stephen; Kramer, Morten

    2012-01-01

    The objective of this abstract is to provide a review of models for motion simulation of marine structures with a special emphasis on wave energy converters. The time-domain model is applied to a point absorber system working in pitch mode only. The device is similar to the well-known Wavestar...... float located in the Danish North Sea. The main objective is to produce a tool that can accurately simulate the dynamics of a floating structure with an arbitrary geometry provided the frequency domain coefficients are calculated beforehand. The latter calculation is based on linear fluid structure...... interaction (small deformations of the fluid surface and body), inviscid incompressible, irrotational flow and a linearized Euler-Bernoulli formulation of the fluid pressure. The time-domain analysis of a floating structure involves the calculation of a convolution integral between the impulse response...

  4. On the concept of sloped motion for free-floating wave energy converters.

    Science.gov (United States)

    Payne, Grégory S; Pascal, Rémy; Vaillant, Guillaume

    2015-10-08

    A free-floating wave energy converter (WEC) concept whose power take-off (PTO) system reacts against water inertia is investigated herein. The main focus is the impact of inclining the PTO direction on the system performance. The study is based on a numerical model whose formulation is first derived in detail. Hydrodynamics coefficients are obtained using the linear boundary element method package WAMIT. Verification of the model is provided prior to its use for a PTO parametric study and a multi-objective optimization based on a multi-linear regression method. It is found that inclining the direction of the PTO at around 50° to the vertical is highly beneficial for the WEC performance in that it provides a high capture width ratio over a broad region of the wave period range.

  5. Study of hydrodynamic characteristics of a Sharp Eagle wave energy converter

    Science.gov (United States)

    Zhang, Ya-qun; Sheng, Song-wei; You, Ya-ge; Huang, Zhen-xin; Wang, Wen-sheng

    2017-06-01

    According to Newton's Second Law and the microwave theory, mechanical analysis of multiple buoys which form Sharp Eagle wave energy converter (WEC) is carried out. The movements of every buoy in three modes couple each other when they are affected with incident waves. Based on the above, mechanical models of the WEC are established, which are concerned with fluid forces, damping forces, hinge forces, and so on. Hydrodynamic parameters of one buoy are obtained by taking the other moving buoy as boundary conditions. Then, by taking those hydrodynamic parameters into the mechanical models, the optimum external damping and optimal capture width ratio are calculated out. Under the condition of the optimum external damping, a plenty of data are obtained, such as the displacements amplitude of each buoy in three modes (sway, heave, pitch), damping forces, hinge forces, and speed of the hydraulic cylinder. Research results provide theoretical references and basis for Sharp Eagle WECs in the design and manufacture.

  6. Comparison and Sensitivity Investigations of a CALM and SALM Type Mooring System for Wave Energy Converters

    Directory of Open Access Journals (Sweden)

    Arthur Pecher

    2014-02-01

    Full Text Available A quasi-static analysis and sensitivity investigation of two different mooring configurations—a single anchor leg mooring (SALM and a three-legged catenary anchor leg system (CALM—is presented. The analysis aims to indicate what can be expected in terms of requirements for the mooring system size and stiffness. The two mooring systems were designed for the same reference load case, corresponding to a horizontal design load at the wave energy converter (WEC of 2000 kN and a water depth of 30 m. This reference scenario seems to be representative for large WECs operating in intermediate water depths, such as Weptos, Wave Dragon and many others, including reasonable design safety factors. Around this reference scenario, the main influential parameters were modified in order to investigate their impact on the specifications of the mooring system, e.g. the water depth, the horizontal design load, and a mooring design parameter.

  7. Investigation and Optimisation of a Discrete Fluid Power PTO-system for Wave Energy Converters

    DEFF Research Database (Denmark)

    Hansen, Anders Hedegaard

    recently focused research on improving the power take off (PTO) system converting the mechanical motion of the floats into electricity. This has brought attention to discrete fluid power (DFP) technology, especially secondary controlled common pressure rail systems. A novel discrete PTO-system has been...... proposed and found feasible for the Wavestar WEC. However, with a technology shift from a continuous to a discrete fluid power PTO-system, new challenges emerge. The current project investigates and optimises the novel discrete fluid power PTO-system proposed for the Wavestar WEC. Initiating from...... an investigation of energy extraction by WECs utilising a discrete PTO force, an investigation of the system configuration is conducted. Hence, the configuration of the multi-chamber cylinder and the common pressure rails are investigated for the discrete fluid power force system. A method for choosing the system...

  8. Control scheme of three-level H-bridge converter for interfacing between renewable energy resources and AC grid

    DEFF Research Database (Denmark)

    Pouresmaeil, Edris; Montesinos-Miracle, Daniel; Gomis-Bellmunt, Oriol

    2011-01-01

    This paper presents a control strategy of multilevel converters for integration of renewable energy resources into power grid. The proposed technique provides compensation for active, reactive, and harmonic current components of grid-connected loads. A three-level H-bridge converter is proposed...... as the interfacing system between renewable energy resources and utility grid. High performance of the proposed technique is indicated with injection of maximum available power from renewable energy resources to the power grid, increases power factor of the utility grid, and reduces the total harmonic distortion...

  9. Control scheme of three-level H-bridge converter for interfacing between renewable energy resources and AC grid

    DEFF Research Database (Denmark)

    Pouresmaeil, Edris; Montesinos-Miracle, Daniel; Gomis-Bellmunt, Oriol

    2011-01-01

    This paper presents a control strategy of multilevel converters for integration of renewable energy resources into power grid. The proposed technique provides compensation for active, reactive, and harmonic current components of grid-connected loads. A three-level H-bridge converter is proposed a...... (THD) of grid current through Matlab/Simulink under proposed operating conditions. © 2011 EPE Association - European Power Electr....

  10. A tapped-inductor buck-boost converter for a multi-DEAP generator energy harvesting system

    Science.gov (United States)

    Dimopoulos, Emmanouil; Munk-Nielsen, Stig

    2014-03-01

    Interest on Dielectric ElectroActive Polymer (DEAP) generators has aroused among scientists in recent years, due to the former ones' documented advantages against competing electromagnetic and field-activated technologies. Yet, the need for bidirectional energy flow under high step-up and high step-down voltage conversion ratios, accompanied by low-average but relatively high-peak currents, imposes great challenges on the design of the employed power electronic converter. On top of that, the shortage of commercially-available, high-efficient, high-voltage, low-power semiconductor devices limits the effective operational range of the power electronic converter. In this paper, a bidirectional tapped-inductor buck-boost converter is proposed, addressing high- efficient high step-up and high step-down voltage conversion ratios, for energy harvesting applications based on DEAP generators. The effective operational range of the converter is extended, by replacing its high-side switch with a string of three serialized MOSFETs, to accommodate the need for high-efficient high-voltage operation. Experiments conducted on a single DEAP generator - part of a quadruple DEAP generator energy harvesting system with all elements installed sequentially in the same circular disk with a 90° phase shift - validate the applicability of the proposed converter, demonstrating energy harvesting of 0.26 J, at 0.5 Hz and 60% delta- strain; characterized by an energy density of 1.25 J per kg of active material.

  11. Performance analysis of a wave energy converter using numerical simulation technique

    Institute of Scientific and Technical Information of China (English)

    Mohammed; Asid; ZULLAH; Deepak; PRASAD; Mohammed; Rafiuddin; AHMED; Young-Ho; LEE

    2010-01-01

    A general purpose viscous flow solver Ansys CFX was used to study a Savonius type wave energy converter in a 3D numerical viscous wave tank.This paper presents the results of a computational fluid dynamics(CFD) analysis of the effect of blade configuration on the performance of two Savonius rotors for wave energy extraction.A piston-type wave generator was incorporated in the computational domain to generate the desired incident waves.A complete OWC system with a 3-bladed Savonius rotor was modeled in a three dimensional numerical wave tank and the hydrodynamic conversion efficiency was estimated.The flow over the rotors was assumed to be two-dimensional(2D),viscous,turbulent and unsteady.The CFX code was used with a solver of the coupled conservation equations of mass,momentum and energy,with an implicit time scheme and with the adoption of the hexahedral mesh and the moving mesh techniques in areas of moving surfaces.Turbulence was modeled with the k-e model.The results indicated that the developed models are suitable to analyze the water flows both in the chamber and in the turbine.For the turbine,the numerical results of pressure and torque were compared for the two cases.

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

    Directory of Open Access Journals (Sweden)

    Marta Molinas

    2013-07-01

    Full Text Available 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.

  13. Balancing Power Output and Structural Fatigue of Wave Energy Converters by Means of Control Strategies

    Directory of Open Access Journals (Sweden)

    Francesco Ferri

    2014-04-01

    Full Text Available In order to reduce the cost of electricity produced by wave energy converters (WECs, the benefit of selling electricity as well as the investment costs of the structure has to be considered. This paper presents a methodology for assessing the control strategy for a WEC with respect to both energy output and structural fatigue loads. Different active and passive control strategies are implemented (proportional (P controller, proportional-integral (PI controller, proportional-integral-derivative with memory compensation (PID controller, model predictive control (MPC and maximum energy controller (MEC, and load time-series resulting from numerical simulations are used to design structural parts based on fatigue analysis using rain-flow counting, Stress-Number (SN curves and Miner’s rule. The objective of the methodology is to obtain a cost-effective WEC with a more comprehensive analysis of a WEC based on a combination of well known control strategies and standardised fatigue methods. The presented method is then applied to a particular case study, the Wavestar WEC, for a specific location in the North Sea. Results, which are based on numerical simulations, show the importance of balancing the gained power against structural fatigue. Based on a simple cost model, the PI controller is shown as a viable solution.

  14. Buck-boost converter for simultaneous semi-active vibration control and energy harvesting for electromagnetic regenerative shock absorber

    Science.gov (United States)

    Li, Peng; Zhang, Chongxiao; Kim, Junyoung; Yu, Liangyao; Zuo, Lei

    2014-04-01

    Regenerative semi-active suspensions can capture the previously dissipated vibration energy and convert it to usable electrical energy for powering on-board electronic devices, while achieve both the better ride comfort and improved road handling performance at the same time when certain control is applied. To achieve this objective, the power electronics interface circuit connecting the energy harvester and the electrical loads, which can perform simultaneous vibration control and energy harvesting function is in need. This paper utilized a buck-boost converter for simultaneous semi-active vibration control and energy harvesting with electromagnetic regenerative shock absorber, which utilizes a rotational generator to converter the vibration energy to electricity. It has been found that when the circuit works in discontinuous current mode (DCM), the ratio between the input voltage and current is only related to the duty cycle of the switch pulse width modulation signal. Using this property, the buck-boost converter can be used to perform semi-active vibration control by controlling the load connected between the terminals of the generator in the electromagnetic shock absorber. While performing the vibration control, the circuit always draw current from the shock absorber and the suspension remain dissipative, and the shock absorber takes no additional energy to perform the vibration control. The working principle and dynamics of the circuit has been analyzed and simulations were performed to validate the concept.

  15. Energy Conversion Module (ECM) - DC/DC converter with integrated supercaps

    Energy Technology Data Exchange (ETDEWEB)

    Ollhaeuser, Helmut [ALCOA/AFL Europe GmbH (Germany)

    2008-07-01

    In the light of increasing hybridization of future vehicle generations mainly those functionalities will be realized which contribute to fuel- and at the end emission-reduction. Recuperation, Start-Stop, E-steering and EDS-stabilization therefore constitute applications for which an efficient energy management has to be provided In this context ALCOA / AFL Europe GmbH developed a patent pending system solution, by which in one single unit a powerful DC/DC converter is integrated with the storage medium EDLC or Super-/Ultracap - on the one hand the restrictive packaging and on the other hand high performance requirements of the OEM can be met in a high degree. Possible issues arising from the compact integration of the supercaps such as heat dissipation and EMI are solved in a unique way - even the impacts in case of a defect cell are eliminated by a sophisticated balancing. The main performance characteristics of the current finished 1 KW solution being in test operation at various OEM are: - Output: 1 KW bidirectional - Capacity: 29,8 F / 12 Cells a 350 F - Additional fused power output - Optional output for consumers during motor start - Protection class IP 6K7 - Buck/Boost converter 2-phases - Operating frequency 125 kHz - Current control and phase monitoring realized in HW With its scaleable approach and the possibility to be integrated rapidly and cost-efficient in new carlines, the ECM just today combines the advantages of an intelligent electric power management. New prospective application-ranges - i.e. up to 5 KW for commercial vehicles and/or buses - are right now under development and clear its way for series implementation, soon. (orig.)

  16. Converting hazardous organics into clean energy using a solar responsive dual photoelectrode photocatalytic fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jianyong; Li, Jinhua, E-mail: lijinhua@sjtu.edu.cn; Chen, Quanpeng; Bai, Jing; Zhou, Baoxue

    2013-11-15

    Highlights: • A dual photoelcetrode PFC for converting hazardous organics into electricity. • The PFC possesses high cell performance operating in various model compounds. • Parameters were studied for optimization of the PFC performance. • Significant removal rate of chroma was observed in azo dyes solutions. -- Abstract: Direct discharging great quantities of organics into water-body not only causes serious environmental pollution but also wastes energy sources. In this paper, a solar responsive dual photoelectrode photocatalytic fuel cell (PFC{sup 2}) based on TiO{sub 2}/Ti photoanode and Cu{sub 2}O/Cu photocathode was designed for hazardous organics treatment with simultaneous electricity generation. Under solar irradiation, the interior bias voltage produced for the Fermi level difference between photoelectrodes drives photoelectrons of TiO{sub 2}/Ti photoanode to combine with photoholes of Cu{sub 2}O/Cu photocathode through external circuit thus generating electricity. In the meantime, organics are decomposed by photoholes remained at TiO{sub 2}/Ti photoanode. By using various hazardous organics including azo dyes as model pollutants, the PFC showed high converting performance of organics into electricity. For example, in 0.05 M phenol solution, a short-circuit current density 0.23 mA cm{sup −2}, open-circuit voltage 0.49 V, maximum power output 0.36 10{sup −4} W cm{sup −2} was achieved. On the other hand, removal rate of chroma reached 67%, 87% and 63% in 8 h for methyl orange, methylene blue, Congo red, respectively.

  17. An oscillating wave energy converter with nonlinear snap-through Power-Take-Off systems in regular waves

    Science.gov (United States)

    Zhang, Xian-tao; Yang, Jian-min; Xiao, Long-fei

    2016-07-01

    Floating oscillating bodies constitute a large class of wave energy converters, especially for offshore deployment. Usually the Power-Take-Off (PTO) system is a directly linear electric generator or a hydraulic motor that drives an electric generator. The PTO system is simplified as a linear spring and a linear damper. However the conversion is less powerful with wave periods off resonance. Thus, a nonlinear snap-through mechanism with two symmetrically oblique springs and a linear damper is applied in the PTO system. The nonlinear snap-through mechanism is characteristics of negative stiffness and double-well potential. An important nonlinear parameter γ is defined as the ratio of half of the horizontal distance between the two springs to the original length of both springs. Time domain method is applied to the dynamics of wave energy converter in regular waves. And the state space model is used to replace the convolution terms in the time domain equation. The results show that the energy harvested by the nonlinear PTO system is larger than that by linear system for low frequency input. While the power captured by nonlinear converters is slightly smaller than that by linear converters for high frequency input. The wave amplitude, damping coefficient of PTO systems and the nonlinear parameter γ affect power capture performance of nonlinear converters. The oscillation of nonlinear wave energy converters may be local or periodically inter well for certain values of the incident wave frequency and the nonlinear parameter γ, which is different from linear converters characteristics of sinusoidal response in regular waves.

  18. Performances of an Interleaved High Step-Up Converter with Different Soft-Switching Snubbers for PV Energy Conversion Applications

    Directory of Open Access Journals (Sweden)

    Sheng-Yu Tseng

    2013-01-01

    Full Text Available This paper proposes an interleaved high step-up converter with different soft-switching snubbers for PV energy conversion applications. For the high step-up converter, interleaved and coupled-inductor technologies are used to reduce output ripple current and increase output power level. Simultaneously, two types of snubbers, a single-capacitor snubber and boost type snubber, are introduced separately into the discussed converters for comparing their performances of conversion efficiency and switching losses. For drawing maximum power from the PV arrays, a perturbation-and-observation method realized with the microcontroller is adopted to achieve maximum power point tracking (MPPT algorithm and power regulating scheme. Finally, two prototypes of the interleaved coupled-inductor boost converter with a single-capacitor snubber and with boost type snubber are implemented, respectively. The experimental results obtained are used to verify and compare the performances and feasibilities of the discussed converters with different snubbers in PV conversion applications. The experimental results show that the proposed system is suitable for PV energy conversion applications when the duty ratios of switches of the converter are less than 0.5.

  19. On The Dynamics and Design of a Two-body Wave Energy Converter

    Science.gov (United States)

    Liang, Changwei; Zuo, Lei

    2016-09-01

    A two-body wave energy converter oscillating in heave is studied in this paper. The energy is extracted through the relative motion between the floating and submerged bodies. A linearized model in the frequency domain is adopted to study the dynamics of such a two-body system with consideration of both the viscous damping and the hydrodynamic damping. The closed form solution of the maximum absorption power and corresponding power take-off parameters are obtained. The suboptimal and optimal designs for a two-body system are proposed based on the closed form solution. The physical insight of the optimal design is to have one of the damped natural frequencies of the two body system the same as, or as close as possible to, the excitation frequency. A case study is conducted to investigate the influence of the submerged body on the absorption power of a two-body system subjected to suboptimal and optimal design under regular and irregular wave excitations. It is found that the absorption power of the two-body system can be significantly higher than that of the single body system with the same floating buoy in both regular and irregular waves. In regular waves, it is found that the mass of the submerged body should be designed with an optimal value in order to achieve the maximum absorption power for the given floating buoy. The viscous damping on the submerged body should be as small as possible for a given mass in both regular and irregular waves.

  20. Analysis of wear in organic and sintered friction materials used in small wind energy converters

    Directory of Open Access Journals (Sweden)

    Jorge Alberto Lewis Esswein Junior

    2008-09-01

    Full Text Available Wind energy converters of small size used in isolated units to generate electrical energy must present low maintenance cost to such facilities economically viable. The aspect to be analyzed in cost reduction is the brake system, since in isolated systems the use of brake is more frequent reducing the brake pads life time. This study aims at analyzing the wear behavior of some materials used in brake pads. An organic material was analyzed comparing it with a commercial brake pad, and the sintered material was developed and tested. The materials behaviors were evaluated in both wear and friction coefficient. The sintered samples were made by powder metallurgy. The composition was compacted at 550 MPa and sintered in a furnace with controlled atmosphere to avoid oxidation. Despite the different compositions of the two types of materials, they presented a very similar wear; however, the sintered material presented a higher friction coefficient. An adjustment in the braking system of the wind generator might be proposed to use the sintered brake pad, due to its higher friction coefficient. Consequently, the braking action becomes lower, reducing the wear rate of the material.

  1. Power angle control of grid-connected voltage source converter in a wind energy application

    Energy Technology Data Exchange (ETDEWEB)

    Svensson, Jan [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Electric Power Engineering

    1995-12-31

    In this thesis, the connection of a voltage source converter to the grid in a wind energy application is examined. The possibility of using a cheap control system without grid current measurements, is investigated. The control method is based on controlling the voltage angle of the inverter, which governs the active power flow. The highest frequency of the power variation, coming from wind turbine, is approx. 5 Hz. Since the proposed control method easily can handle such power variations it is very well suited for wind turbine applications. The characteristics of the system depend on the DC-link capacitor, the grid filter inductance and resistance. Large values of the resistance damp the system well but increase the energy losses. A high inductance leads to a reduced harmonic level on the grid but makes the system slower. By using feed-forward of the generator/rectifier current signal, the performance is increased compared to an ordinary PI-control. Combining the Linear Quadratic (LQ) control method with Kalman filtered input signals, a robust control method with a good performance is obtained. The LQ controller controls both the phase displacement angle and the modulation index, resulting in higher bandwidth, and the typical power angle resonance at the grid frequency disappears. 22 refs, 109 figs, 14 tabs

  2. Measurements of overtopping flow time series on the Wave Dragon, wave energy converter

    Energy Technology Data Exchange (ETDEWEB)

    Tedd, James; Peter Kofoed, Jens [Department of Civil Engineering, Aalborg University, Sohngaardhomsvej 57, Aalborg 9000 (Denmark)

    2009-03-15

    A study of overtopping flow series on the Wave Dragon prototype, a low crested device designed to maximise flow, in a real sea, is presented. This study aims to fill the gap in the literature on time series of flow overtopping low crested structures. By comparing to a simulated flow the characteristics of the overtopping flow are discussed and the simulation algorithm is tested. Measured data is shown from a storm build up in October 2006, from the Wave Dragon prototype situated in an inland sea in Northern Denmark. This wave energy converter extracts energy from the waves, by funnelling them to run-up a ramp and overtop into a reservoir. This water is stored at a higher level than the average sea surface, before being discharged through hydro turbines. The waves, device sea handling and overtopping flow are measured by pressure transducers ahead of, beneath and in the device. Comparisons of the distribution and correlation show that the measurements support the use of the algorithm for generating a simulated flow. (author)

  3. Optimizing the Performance of Solo Duck Wave Energy Converter in Tide

    Directory of Open Access Journals (Sweden)

    Jinming Wu

    2017-02-01

    Full Text Available The high efficiency performance of the Edinburgh Duck wave energy converter (WEC in 2D regular wave tests makes it a promising wave energy conversion scheme. A solo Duck WEC will be able to apply the point absorber effect to further enhance its performance. Since released degree of freedom will decrease the efficiency, a Duck WEC with fixed pitching axis will be a better option. However, for fixed supported WECs, tide is a non-ignorable consideration. In this paper, a movable mass method is utilized in the whole tidal range to not only balance the Duck to appropriate beak angles, but also follow the variation of hydrodynamic coefficients to keep cancelling the reactance of the system impedance so that complex conjugate control can be realized to optimize the power capture performance of the Duck WEC in tide. Results show that the beak angle should be adjusted to as large a value as possible so that the response amplitude of the Duck at maximum relative capture width will be reasonable small, and the lowest weight of the movable mass is found when its designed position locates at the center of the Duck profile.

  4. Modeling of In-stream Tidal Energy Development and its Potential Effects in Tacoma Narrows, Washington, USA

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zhaoqing; Wang, Taiping; Copping, Andrea E.; Geerlofs, Simon H.

    2014-10-01

    Understanding and providing proactive information on the potential for tidal energy projects to cause changes to the physical system and to key water quality constituents in tidal waters is a necessary and cost-effective means to avoid costly regulatory involvement and late stage surprises in the permitting process. This paper presents a modeling study for evaluating the tidal energy extraction and its potential impacts on the marine environment in a real world site - Tacoma Narrows of Puget Sound, Washington State, USA. An unstructured-grid coastal ocean model, fitted with a module that simulates tidal energy devices, was applied to simulate the tidal energy extracted by different turbine array configurations and the potential effects of the extraction at local and system-wide scales in Tacoma Narrows and South Puget Sound. Model results demonstrated the advantage of an unstructured-grid model for simulating the far-field effects of tidal energy extraction in a large model domain, as well as assessing the near-field effect using a fine grid resolution near the tidal turbines. The outcome shows that a realistic near-term deployment scenario extracts a very small fraction of the total tidal energy in the system and that system wide environmental effects are not likely; however, near-field effects on the flow field and bed shear stress in the area of tidal turbine farm are more likely. Model results also indicate that from a practical standpoint, hydrodynamic or water quality effects are not likely to be the limiting factor for development of large commercial-scale tidal farms. Results indicate that very high numbers of turbines are required to significantly alter the tidal system; limitations on marine space or other environmental concerns are likely to be reached before reaching these deployment levels. These findings show that important information obtained from numerical modeling can be used to inform regulatory and policy processes for tidal energy development.

  5. Wave Energy Assessment and Performance Estimation of State of the Art Wave Energy Converters in Italian Hotspots

    Directory of Open Access Journals (Sweden)

    Valentina Vannucchi

    2016-12-01

    Full Text Available This paper presents an assessment of offshore wave energy potential at the scale of the whole Mediterranean Sea. The offshore wave data were propagated, by means of numerical modeling, toward four Italian coastal areas, namely stretches of coast of Tuscany, Liguria, Sardinia and Sicily. For each area, the wave power and the monthly, seasonal and annual variability at water depths of 50 m and 15 m were analyzed and hotspots were located. The results show strong variability of the wave energy potential from point to point of the same area thus highlighting the need for spatially detailed analysis. The higher values of wave energy potential are located in the hotspots of Sardinia and Sicily, at 11.4 kW/m and 9.1 kW/m, respectively. The Tuscany and the Liguria hotspots are characterized, respectively, by 4.7 kW/m and 2.0 kW/m. In order to point out which state of the art WEC is best suited for the Italian areas, the performances of six different state of the art Wave Energy Converters (WECs were evaluated. Finally, a comparison of the performances of each WEC in the selected Italian sites and in some European (EU oceanic sites was conducted. The energy potential in the most energetic EU oceanic site, among those here investigated, is up to 38-times greater than the potentials in the studied Italian areas but the power output, of the best WEC technology, is no more than nine times greater.

  6. Development and implementation of a compound converter in solar energy systems

    Directory of Open Access Journals (Sweden)

    S. J. B. Hartman

    1992-07-01

    Full Text Available The converter proposed here is a compound photovoltaic converter system that has been implemented with a power rating of 1,5 kVA at an array voltage of 96 V, using a 24 V battery bank. The converter system combines the functions of inversion, battery regulation and maximum power point tracking of the solar array into a single cost-effective converter. Maximum power point tracking is performed by controlling the voltage and frequency of the AC output. A description of this converter, and an explanation of the control strategy employed, are provided together with practical results measured on the prototype converter. This compound topology has a high conversion efficiency from solar array to load.

  7. Active energy recovery clamping circuit to improve the performance of power converters

    Energy Technology Data Exchange (ETDEWEB)

    Whitaker, Bret; Barkley, Adam

    2017-05-09

    A regenerative clamping circuit for a power converter using clamping diodes to transfer charge to a clamping capacitor and a regenerative converter to transfer charge out of the clamping capacitor back to the power supply input connection. The regenerative converter uses a switch connected to the midpoint of a series connected inductor and capacitor. The ends of the inductor and capacitor series are connected across the terminals of the power supply to be in parallel with the power supply.

  8. Design and Implementation of Power Converters for Hybrid Wind-Solar Energy Conversion System with an Implementation of MPPT

    Directory of Open Access Journals (Sweden)

    G. Sridhar Babu

    2013-11-01

    Full Text Available This paper presents the design and implementation of power converters for wind conversion systems. The power converter can not only transfer the power from a wind generator, but also improve the stability and safety of the system. The proposed system consists of a Permanent magnet synchronous generator (PMSG; a DC/DC boosts converter, a bi-directional DC/DC converter and a full-bridge DC/AC inverter. The wind generator is the main power source of the system, and the battery is used for energy storage and power compensation to recover the natural irregularity of the wind power. In this paper presents a new system configuration of the front-end rectifier stage for a hybrid wind or photo voltaic energy system. The configuration allows the two sources to supply the load separately or simultaneously, depending on the availability of energy sources. The inherent nature of this cuk-scpic fused converter, additional input filters are not necessary to filter out high frequency harmonic content is determinant for the generator life span, heating issue and efficiency. The fused multi-input rectifier stage also allows maximum power from the wind and sun. When it is available an adaptive MPPT algorithm will be used for photo voltaic (PV system. Operational analysis of the roposed system, will discoursed in this paper simulation results are given to highlight the merit of the proposed circuit.

  9. Oceanic Platform of the Canary Islands: an ocean testbed for ocean energy converters

    Science.gov (United States)

    González, Javier; Hernández-Brito, Joaquín.; Llinás, Octavio

    2010-05-01

    not particularly powerful with values around 40-50 cm/s. However a detailed assessment, based on field measurements, will be conducted in the near future with the aim to identify specific areas close to the coast with stronger currents which make suitable the deployment of marine current turbines. Although the base Platform is not still available, PLOCAN has already started the activity as an ocean testbed providing services to a wave energy converter patented by the Spanish company PIPO Systems. A scaled 1:5 prototype will be deployed during January 2010 and monitored for several months. Current facilities available include some ODAS buoys (temperature, salinity, pH, oxygen, turbidity, wind, etc.), wave rider buoy, current meter profilers (ADCP and electromagnetic), system for data management, remote operated vehicles (ROV), autonomous underwater vehicles (AUV), and an oceanographic vessel. Future facilities include high frequency radar for wave and current measurements and submarine electro-optical cables to connect the Platform with the energy converters and with the shore station.

  10. An iterative approach for symmetrical and asymmetrical Short-circuit calculations with converter-based connected renewable energy sources

    DEFF Research Database (Denmark)

    Göksu, Ömer; Teodorescu, Remus; Bak-Jensen, Birgitte;

    2012-01-01

    As more renewable energy sources, especially more wind turbines are installed in the power system, analysis of the power system with the renewable energy sources becomes more important. Short-circuit calculation is a well known fault analysis method which is widely used for early stage analysis...... and design purposes and tuning of the network protection equipments. However, due to current controlled power converter-based grid connection of the wind turbines, short-circuit calculation cannot be performed with its current form for networks with power converter-based wind turbines. In this paper......, an iterative approach for short-circuit calculation of networks with power converter-based wind turbines is developed for both symmetrical and asymmetrical short-circuit grid faults. As a contribution to existing solutions, negative sequence current injection from the wind turbines is also taken into account...

  11. Wave-to-wire Modelling of Wave Energy Converters : Critical Assessment, Developments and Applicability for Economical Optimisation

    DEFF Research Database (Denmark)

    Ferri, Francesco

    untapped, renewable energy resource that has the potential to contribute significantly to the future energy mix, especially in an environmental friendly future scenario. What is bounding the sector to roll off into the market is the cost of the produced energy: too high if compared with other renewable......The idea to use the motion of a wavy sea surface to produce electricity was investigate in the seventies, in a time when the earliest wave energy converters were conceived and developed. But nowadays still none of the patented devices reached a commercial stage. Wave energy is a large, mostly...

  12. Modularized multilevel and z-source power converter as renewable energy interface for vehicle and grid-connected applications

    Science.gov (United States)

    Cao, Dong

    Due the energy crisis and increased oil price, renewable energy sources such as photovoltaic panel, wind turbine, or thermoelectric generation module, are used more and more widely for vehicle and grid-connected applications. However, the output of these renewable energy sources varies according to different solar radiation, wind speed, or temperature difference, a power converter interface is required for the vehicle or grid-connected applications. Thermoelectric generation (TEG) module as a renewable energy source for automotive industry is becoming very popular recently. Because of the inherent characteristics of TEG modules, a low input voltage, high input current and high voltage gain dc-dc converters are needed for the automotive load. Traditional high voltage gain dc-dc converters are not suitable for automotive application in terms of size and high temperature operation. Switched-capacitor dc-dc converters have to be used for this application. However, high voltage spike and EMI problems exist in traditional switched-capacitor dc-dc converters. Huge capacitor banks have to be utilized to reduce the voltage ripple and achieve high efficiency. A series of zero current switching (ZCS) or zero voltage switching switched-capacitor dc-dc converters have been proposed to overcome the aforementioned problems of the traditional switched-capacitor dc-dc converters. By using the proposed soft-switching strategy, high voltage spike is reduced, high EMI noise is restricted, and the huge capacitor bank is eliminated. High efficiency, high power density and high temperature switched-capacitor dc-dc converters could be made for the TEG interface in vehicle applications. Several prototypes have been made to validate the proposed circuit and confirm the circuit operation. In order to apply PV panel for grid-connected application, a low cost dc-ac inverter interface is required. From the use of transformer and safety concern, two different solutions can be implemented, non

  13. Converting hazardous organics into clean energy using a solar responsive dual photoelectrode photocatalytic fuel cell.

    Science.gov (United States)

    Li, Jianyong; Li, Jinhua; Chen, Quanpeng; Bai, Jing; Zhou, Baoxue

    2013-11-15

    Direct discharging great quantities of organics into water-body not only causes serious environmental pollution but also wastes energy sources. In this paper, a solar responsive dual photoelectrode photocatalytic fuel cell (PFC(2)) based on TiO2/Ti photoanode and Cu2O/Cu photocathode was designed for hazardous organics treatment with simultaneous electricity generation. Under solar irradiation, the interior bias voltage produced for the Fermi level difference between photoelectrodes drives photoelectrons of TiO2/Ti photoanode to combine with photoholes of Cu2O/Cu photocathode through external circuit thus generating electricity. In the meantime, organics are decomposed by photoholes remained at TiO2/Ti photoanode. By using various hazardous organics including azo dyes as model pollutants, the PFC showed high converting performance of organics into electricity. For example, in 0.05 M phenol solution, a short-circuit current density 0.23 mA cm(-2), open-circuit voltage 0.49 V, maximum power output 0.3610(-4)W cm(-2) was achieved. On the other hand, removal rate of chroma reached 67%, 87% and 63% in 8h for methyl orange, methylene blue, Congo red, respectively. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. Coupled Mooring Analyses for the WEC-Sim Wave Energy Converter Design Tool: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Sirnivas, Senu; Yu, Yi-Hsiang; Hall, Matthew; Bosma, Bret

    2016-07-01

    A wave-energy-converter-specific time-domain modeling method (WEC-Sim) was coupled with a lumped-mass-based mooring model (MoorDyn) to improve its mooring dynamics modeling capability. This paper presents a verification and validation study on the coupled numerical method. First, a coupled model was built to simulate a 1/25 model scale floating power system connected to a traditional three-point catenary mooring with an angle of 120 between the lines. The body response and the tension force on the mooring lines at the fairlead in decay tests and under regular and irregular waves were examined. To validate and verify the coupled numerical method, the simulation results were compared to the measurements from a wave tank test and a commercial code (OrcaFlex). Second, a coupled model was built to simulate a two-body point absorber system with a chain-connected catenary system. The influence of the mooring connection on the point absorber was investigated. Overall, the study showed that the coupling of WEC-Sim and the MoorDyn model works reasonably well for simulating a floating system with practical mooring designs and predicting the corresponding dynamic loads on the mooring lines. Further analyses on improving coupling efficiency and the feasibility of applying the numerical method to simulate WEC systems with more complex mooring configuration are still needed.

  15. Application of the Most Likely Extreme Response Method for Wave Energy Converters: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Quon, Eliot; Platt, Andrew; Yu, Yi-Hsiang; Lawson, Michael

    2016-07-01

    Extreme loads are often a key cost driver for wave energy converters (WECs). As an alternative to exhaustive Monte Carlo or long-term simulations, the most likely extreme response (MLER) method allows mid- and high-fidelity simulations to be used more efficiently in evaluating WEC response to events at the edges of the design envelope, and is therefore applicable to system design analysis. The study discussed in this paper applies the MLER method to investigate the maximum heave, pitch, and surge force of a point absorber WEC. Most likely extreme waves were obtained from a set of wave statistics data based on spectral analysis and the response amplitude operators (RAOs) of the floating body; the RAOs were computed from a simple radiation-and-diffraction-theory-based numerical model. A weakly nonlinear numerical method and a computational fluid dynamics (CFD) method were then applied to compute the short-term response to the MLER wave. Effects of nonlinear wave and floating body interaction on the WEC under the anticipated 100-year waves were examined by comparing the results from the linearly superimposed RAOs, the weakly nonlinear model, and CFD simulations. Overall, the MLER method was successfully applied. In particular, when coupled to a high-fidelity CFD analysis, the nonlinear fluid dynamics can be readily captured.

  16. Numerical Simulation of Section Systems in the Pelamis Wave Energy Converter

    Directory of Open Access Journals (Sweden)

    Hongzhou He

    2013-01-01

    Full Text Available The working principle of the Pelamis wave energy converter is described in this paper. The sectional size suitable for the outside sea of Xiamen Bay is redesigned according to the Froude and Strouhal similarity criteria. The swing angles, hydrodynamic coefficients, and wave exciting forces are calculated based on the AQWA hydrodynamic software and the average outside sea condition of Xiamen Bay. It is concluded that the Pelamis after redesigned by the Froude and Strouhal similarity criteria can run better in the outside sea area of Xiamen Bay. The three sections indirectly contacted with the fixed axis have larger swing angles. The wave period and height affect the speed ofthe response of the section and its swing angle range, respectively. The larger the total forces, the larger the swing angles. The wave circular frequency has a greater effect on the added mass and the wave exciting force than on the radiation damping; the heave added mass and the heave wave exciting force will become smaller when the heave radiation damping becomes larger with the increase of the wave circular frequency.

  17. Coupled Mooring Analyses for the WEC-Sim Wave Energy Converter Design Tool

    Energy Technology Data Exchange (ETDEWEB)

    Sirnivas, Senu; Yu, Yi-Hsiang; Hall, Matthew; Bosma, Bret

    2016-06-24

    A wave-energy-converter-specific time-domain modeling method (WEC-Sim) was coupled with a lumped-mass-based mooring model (MoorDyn) to improve its mooring dynamics modeling capability. This paper presents a verification and validation study on the coupled numerical method. First, a coupled model was built to simulate a 1/25 model scale floating power system connected to a traditional three-point catenary mooring with an angle of 120 between the lines. The body response and the tension force on the mooring lines at the fairlead in decay tests and under regular and irregular waves were examined. To validate and verify the coupled numerical method, the simulation results were compared to the measurements from a wave tank test and a commercial code (OrcaFlex). Second, a coupled model was built to simulate a two-body point absorber system with a chain-connected catenary system. The influence of the mooring connection on the point absorber was investigated. Overall, the study showed that the coupling of WEC-Sim and the MoorDyn model works reasonably well for simulating a floating system with practical mooring designs and predicting the corresponding dynamic loads on the mooring lines. Further analyses on improving coupling efficiency and the feasibility of applying the numerical method to simulate WEC systems with more complex mooring configuration are still needed.

  18. Application of the Most Likely Extreme Response Method for Wave Energy Converters

    Energy Technology Data Exchange (ETDEWEB)

    Quon, Eliot; Platt, Andrew; Yu, Yi-Hsiang; Lawson, Michael

    2016-06-24

    Extreme loads are often a key cost driver for wave energy converters (WECs). As an alternative to exhaustive Monte Carlo or long-term simulations, the most likely extreme response (MLER) method allows mid- and high-fidelity simulations to be used more efficiently in evaluating WEC response to events at the edges of the design envelope, and is therefore applicable to system design analysis. The study discussed in this paper applies the MLER method to investigate the maximum heave, pitch, and surge force of a point absorber WEC. Most likely extreme waves were obtained from a set of wave statistics data based on spectral analysis and the response amplitude operators (RAOs) of the floating body; the RAOs were computed from a simple radiation-and-diffraction-theory-based numerical model. A weakly nonlinear numerical method and a computational fluid dynamics (CFD) method were then applied to compute the short-term response to the MLER wave. Effects of nonlinear wave and floating body interaction on the WEC under the anticipated 100-year waves were examined by comparing the results from the linearly superimposed RAOs, the weakly nonlinear model, and CFD simulations. Overall, the MLER method was successfully applied. In particular, when coupled to a high-fidelity CFD analysis, the nonlinear fluid dynamics can be readily captured.

  19. A dual resonant rectilinear-to-rotary oscillation converter for low frequency broadband electromagnetic energy harvesting

    Science.gov (United States)

    Deng, Wei; Wang, Ya

    2017-09-01

    This paper reports a dual resonant rectilinear-to-rotary oscillation converter (RROC) for low frequency broadband electromagnetic energy harvesting from ambient vibrations. An approximate theoretical model has been established to integrate the electromechanical coupling into a comprehensive electromagnetic-dynamic model of the dual resonant RROC. Numerical simulation has proved the nature of dual resonances by revealing that both the rectilinear resonance and the rotary resonance could be achieved when the stand-alone rectilinear oscillator (RLO) and the stand-alone rotary oscillator (RTO) were excited independently. Simulation on the magnetically coupled RROC has also shown that the rectilinear resonance and the rotary resonance could be obtained simultaneously in the low-frequency region (2-14 Hz) with well-defined restoring torque (M r ) and the initial rotation angle of the RLO (ψ). The magnetic interaction patterns between the rectilinear and the RTOs have been categorized based on aforementioned simulation results. Both simulation and experimental results have demonstrated broadband output attributing from the dual resonances. Experimental results have also indicated that the RROC could have wide bandwidth in a much lower frequency region (2-8 Hz) even without the rotary resonance as long as the system parameters are carefully tuned. Parameter analysis on different values of M r and ψ are experimentally carried out to provide a quantitative guidance of designing the RROC to achieve an optimal power density.

  20. Formalization of common power and efficiency definitions for energy-converting intracellular biochemical processes

    Energy Technology Data Exchange (ETDEWEB)

    Santillan, M.; Angulo-Brown, F.; Chavoya-Aceves, O. [Instituto Politecnico Nacional, Mexico, D. F. (Mexico)

    2001-04-01

    The definitions of power and efficiency for energy-converting intracellular biochemical processes, introduced by Caplan and Essig are studied. These definitions are recovered in the present work with the formalism of De Groot and Mazure for First-Order Irreversible Thermodynamics, rather than the formalism of Prigogine, as done by Caplan and Essig. The approach here employed permits to keep track of all the assumptions in a more clear manner, and to get rid of a very strong restriction in the approach of Caplan and Essig which assumes that the chemical potentials are homogeneous inside the cell. [Spanish] Se estudian las definiciones de potencia y eficiencia para procesos bioquimicos intracelulares convertidores de energia, introducidas por Caplan y Essig. En el presente trabajo, dichas definiciones se recuperan usando el formalismo de De Groot y Mazur para la termodinamica irreversible de primer orden, en vez del formalismo de Prigogine, empleado por Caplan y Essig. El punto de vista empleado en el presente manuscrito permite seguir las suposiciones hechas de una manera mas clara, ademas de que hace innecesaria una suposicion bastante fuerte usada por Caplan y Essig, la cual da por hecho que los potenciales quimicos son homogeneos en el interior de la celula.

  1. Hydrodynamic analysis and shape optimization for vertical axisymmetric wave energy converters

    Science.gov (United States)

    Zhang, Wan-chao; Liu, Heng-xu; Zhang, Liang; Zhang, Xue-wei

    2016-12-01

    The absorber is known to be vertical axisymmetric for a single-point wave energy converter (WEC). The shape of the wetted surface usually has a great influence on the absorber's hydrodynamic characteristics which are closely linked with the wave power conversion ability. For complex wetted surface, the hydrodynamic coefficients have been predicted traditionally by hydrodynamic software based on the BEM. However, for a systematic study of various parameters and geometries, they are too multifarious to generate so many models and data grids. This paper examines a semi-analytical method of decomposing the complex axisymmetric boundary into several ring-shaped and stepped surfaces based on the boundary discretization method (BDM) which overcomes the previous difficulties. In such case, by using the linear wave theory based on eigenfunction expansion matching method, the expressions of velocity potential in each domain, the added mass, radiation damping and wave excitation forces of the oscillating absorbers are obtained. The good astringency of the hydrodynamic coefficients and wave forces are obtained for various geometries when the discrete number reaches a certain value. The captured wave power for a same given draught and displacement for various geometries are calculated and compared. Numerical results show that the geometrical shape has great effect on the wave conversion performance of the absorber. For absorbers with the same outer radius and draught or displacement, the cylindrical type shows fantastic wave energy conversion ability at some given frequencies, while in the random sea wave, the parabolic and conical ones have better stabilization and applicability in wave power conversion.

  2. Physical Modelling of an Array of 25 Heaving Wave Energy Converters to Quantify Variation of Response and Wave Conditions

    DEFF Research Database (Denmark)

    2013-01-01

    for the evaluation of array interaction models and environmental scale models. Each wave energy converter unit has a diameter of 0.315 m and power absorption is due to friction of both a power take off system and bearings. Response is measured on all floats and surge force on five floats. Wave gauges are located...

  3. User's manual: Computer-aided design programs for inductor-energy-storage dc-to-dc electronic power converters

    Science.gov (United States)

    Huffman, S.

    1977-01-01

    Detailed instructions on the use of two computer-aided-design programs for designing the energy storage inductor for single winding and two winding dc to dc converters are provided. Step by step procedures are given to illustrate the formatting of user input data. The procedures are illustrated by eight sample design problems which include the user input and the computer program output.

  4. Design and Implementation of a Power Converter to Process Renewable Energy for Step-down Voltage Applications

    Directory of Open Access Journals (Sweden)

    Chih-Lung Shen

    2014-04-01

    Full Text Available In this study a power converter to process renewable energy is proposed, which can not only process solar energy but deal with wind power. The proposed converter is derived from two series modified forwards to step down voltage for charger system or dc distribution application, so as called Modified-Forward Dual-Input Converter (MFDIC. The MFDIC mainly contains an upper Modified Forward (MF, a lower MF, a common output inductor and a DSP-based system controller. The upper and lower MFs can operate individually or simultaneously to accommodate the variation of atmospheric conditions. Since the MFDIC can process renewable power with interleaved operation, the ripple of output current is suppressed significantly and thus better performance is achieved. In the MFDIC only a common output inductor is needed, instead of two separated inductors, so that the volume of the converter is reduced significantly. To draw maximum power from PV panel and wind turbine, perturb-and-observe method is adopted to achieve the feature of Maximum Power Point Tracking (MPPT. The MFDIC is constructed, designed, analyzed, simulated and tested. Simulations and practical measurements have demonstrated the validity and the feasibility of the proposed dual-input converter.

  5. Energy Storage System by Means of Improved Thermal Performance of a 3 MW Grid Side Wind Power Converter

    DEFF Research Database (Denmark)

    Qin, Zian; Liserre, Marco; Blaabjerg, Frede

    2013-01-01

    method of the energy storage system. Then the conventional thermal evaluation approach is simplified for evaluation with long term wind profile. The case studies are done to address the optimal power size and capacity of the energy storage system by comparing the improvement of the thermal performance......Wind speed variations make the power of wind turbine system to fluctuate, which could increase the thermal stress of the power converter and reduce its lifetime. In order to relieve this problem, short-term energy storage technologies are applied to improve the thermal performance of a 3 MW grid...... side wind power converter. The cost, weight and cycle life of the energy storage technologies are evaluated based on a typical low speed high turbulence wind profile. In detail, a wind turbine system model is established and its control strategy is illustrated, which is followed by the power control...

  6. 13{sup th} Kassel symposium energy systems technology. Power converters in grids. Proceedings; 13. Kasseler Symposium Energie-Systemtechnik. Stromrichter in Netzen. Tagungsband

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2008-07-01

    Increasingly static converters are used for the integration of distributed power generators into the grid, e.g. photovoltaic systems and speed-variable wind energy converters. Also other power generators, storage systems and electrical loads are integrated via power electronics. A variety of product specific standards had been developed for integrating converters into the grid. These standards had emerged parallel to each other as a result of the demands of different forms of energy for the feed-in and consumption of electrical power. Meanwhile it became clear that applications which are sometimes very similar are determined differently by these standards. A further demand for harmonisation arises naturally in the international standardisation. In the run-up to the Symposium the second DERlab workshop 'European DERlab Workshop on Grid Inverters' will be held to prepare an international white book. The white book will be titled 'International White Book on Grid Inverters' and will describe medium to long-term tasks for the standardisation of grid-coupled converters. The 13th Kassel Symposium will give an overview of the wide range of applications of power electronic converters in the grid. Hereby similarities and differences should be disclosed, which will create a basis for further expert talks about the transition of our power supply to an increasing share of grid-coupled converters. Questions which will be discussed include: - What does a high share of converters mean for stability, safety and quality of the grid? - Is it necessary to adapt power system protection technology and safety regulations? - How shall converters act in the future, what is technically feasible, what is economically reasonable? - Are all converter-coupled systems able to provide ancillary services? - How will the grid codes change? Most of the presentations will be in German, simultaneous interpretation will be available. This book is prepared to give you a survey on

  7. A variable step-down conversion ratio switched capacitor DC-DC converter for energy harvesting systems working in intermittent mode

    Energy Technology Data Exchange (ETDEWEB)

    Hao Wenhan; Jia Chen; Chen Hong; Zhang Chun; Wang Zhihua, E-mail: haowh04@mails.tsinghua.edu.c [Tsinghua National Laboratory for Information Science and Technology, Institute of Microelectronics, Tsinghua University, Beijing 100084 (China)

    2009-12-15

    Energy harvesting systems stimulate the development of power management for low power consumption applications. Improving the converter efficiency of power management circuits has become a significant issue in energy harvesting system design. This paper presents a variable step-down conversion ratio switched capacitor (SC) DC-DC converter to advance the converter efficiency of charge on the stored capacitor in a wireless monitoring system of orthopedic implants. The converter is designed to work at 1 MHz switching frequency and achieves 15 to 2 V conversion. Measurement results show that the converter efficiency can reach 42% including all circuit power consumption, which is much higher than previous work. (semiconductor integrated circuits)

  8. A variable step-down conversion ratio switched capacitor DC-DC converter for energy harvesting systems working in intermittent mode

    Institute of Scientific and Technical Information of China (English)

    Hao Wenhan; Jia Chen; Chen Hong; Zhang Chun; Wang Zhihua

    2009-01-01

    Energy harvesting systems stimulate the development of power management for low power consumption applications. Improving the converter efficiency of power management circuits has become a significant issue in energy harvesting system design. This paper presents a variable step-down conversion ratio switched capacitor (SC)DC-DC converter to advance the converter efficiency of charge on the stored capacitor in a wireless monitoring system of orthopedic implants. The converter is designed to work at 1 MHz switching frequency and achieves 15 to 2 V conversion. Measurement results show that the converter efficiency can reach 4:2% including all circuit power consumption, which is much higher than previous work.

  9. Optimized MPPT-based converter for TEG energy harvester to power wireless sensor and monitoring system in nuclear power plant

    Science.gov (United States)

    Xing, Shaoxu; Anakok, Isil; Zuo, Lei

    2017-04-01

    Accidents like Fukushima Disasters push people to improve the monitoring systems for the nuclear power plants. Thus, various types of energy harvesters are designed to power these systems and the Thermoelectric Generator (TEG) energy harvester is one of them. In order to enhance the amount of harvested power and the system efficiency, the power management stage needs to be carefully designed. In this paper, a power converter with optimized Maximum Power Point Tracking (MPPT) is proposed for the TEG Energy Harvester to power the wireless sensor network in nuclear power plant. The TEG Energy Harvester is installed on the coolant pipe of the nuclear plant and harvests energy from its heat energy while the power converter with optimized MPPT can make the TEG Energy Harvester output the maximum power, quickly response to the voltage change and provide sufficient energy for wireless sensor system to monitor the operation of the nuclear power plant. Due to the special characteristics of the Single-Ended Primary Inductor Converter (SEPIC) when it is working in the Discontinuous Inductor Current Mode (DICM) and Continuous Conduction Mode (CCM), the MPPT method presented in this paper would be able to control the converter to achieve the maximum output power in any working conditions of the TEG system with a simple circuit. The optimized MPPT algorithm will significantly reduce the cost and simplify the system as well as achieve a good performance. Experiment test results have shown that, comparing to a fixed- duty-cycle SEPIC which is specifically designed for the working on the secondary coolant loop in nuclear power plant, the optimized MPPT algorithm increased the output power by 55%.

  10. Energy efficiency by means of speed regulated drives with frequency converters; Energieeffizienz durch drehzahlgeregelte Antriebe mit Frequenzumformern

    Energy Technology Data Exchange (ETDEWEB)

    Ristimaeki, Tomi [Centraline c/o Honeywell GmbH, Schoenaich (Germany)

    2009-12-15

    Due to continuously increasing energy prices, companies ever more frequently are compelled to energy conservation and cost savings. The use of frequency converters for speed regulation of turbomachines such as pumps, fans and compressors is not a new idea. The new technologies within this range make this alternative still more attractive due to the smaller costs. The use of electric motors with variable speed regulation in HLK systems offers a large potential for energy conservation. This technology makes a substantial contribution to the adherence of local and international agreements and standards in the range of the energy-saving policy and the lowering of the CO{sub 2} emissions.

  11. Posicast control within feedback structure for a DC-DC single ended primary inductor converter in renewable energy applications

    Energy Technology Data Exchange (ETDEWEB)

    Kalantar, M.; Mousavi G., S.M. [Center of Excellence for Power System Automation and Operation, Department of Electrical Engineering, Iran University of Science and Technology, Narmak, Tehran (Iran)

    2010-10-15

    In this paper, modeling, analysis, design, simulation and control of a single ended primary inductor converter (SEPIC) are discussed for renewable energy applications. Because the traditional control methods such as proportional-integral-derivative (PID) and classical half-cycle Posicast controllers based on feedforward are sensitive to noise and variations in natural frequency, a Posicast control with feedback structure is proposed and designed to reduce or rejection undesirable sensitivity greatly, to suppress measurement noise and to eliminate the overshoot in the output response. The SEPIC converter is modeled using average value modeling analysis. Dynamic modeling and simulation are accomplished using MATLAB Simulink trademark 7.2. (author)

  12. On Peak Mooring Loads and the Influence of Environmental Conditions for Marine Energy Converters

    Directory of Open Access Journals (Sweden)

    Violette Harnois

    2016-04-01

    Full Text Available Mooring systems are among the most critical sub-systems for floating marine energy converters (MEC. In particular, the occurrence of peak mooring loads on MEC mooring systems must be carefully evaluated in order to ensure a robust and efficient mooring design. This understanding can be gained through long-term field test measurement campaigns, providing mooring and environmental data for a wide range of conditions. This paper draws on mooring tensions and environmental conditions that have been recorded (1 for several months during the demonstration of an MEC device and (2 over a period of 18 months at a mooring test facility. Both systems were installed in a shallow water depth (45 m and 30 m, respectively using compliant multi-leg catenary mooring systems. A methodology has been developed to detect peak mooring loads and to relate them to the associated sea states for further investigation. Results indicate that peak mooring loads did not occur for the sea states on the external contour line of the measured sea states, but for the sea states inside the scatter diagram. This result is attributed to the short-term variability associated with the maximum mooring load for the given sea state parameters. During the identified sea states, MEC devices may not be in survival mode, and thus, the power take-off (PTO and ancillary systems may be prone to damage. In addition, repeated high peak loads will significantly contribute to mooring line fatigue. Consequently, considering sea states inside the scatter diagram during the MEC mooring design potentially yields a more cost-effective mooring system. As such, the presented methodology contributes to the continuous development of specific MEC mooring systems.

  13. Numerical Modeling on Hydrodynamic Performance of A Bottom-Hinged Flap Wave Energy Converter

    Institute of Scientific and Technical Information of China (English)

    ZHAO Hai-tao; SUN Zhi-lin; HAO Chun-ling; SHEN Jia-fa

    2013-01-01

    The hydrodynamic performance of a bottom-hinged flap wave energy converter (WEC) is investigated through a frequency domain numerical model.The numerical model is verified through a two-dimensional analytic solution,as well as the qualitative analysis on the dynamic response of avibrating system.The concept of "optimum density" of the bottom-hinged flap is proposed,and its analytic expression is derived as well.The frequency interval in which the optimum density exists is also obtained.The analytic expression of the optimum linear damping coefficient is obtained by a bottom-hinged WEC.Some basic dynamic properties involving natural period,excitation moment,pitch amplitude,and optimum damping coefficient are analyzed and discussed in detail.In addition,this paper highlights the analysis of effects on the conversion performance of the device exerted by some important parameters.The results indicate that "the optimum linear damping period of 5.0 s" is the most ideal option in the short wave sea states with the wave period below 6.0 s.Shallow water depth,large flap thickness and low flap density are advised in the practical design of the device in short wave sea states in order to maximize power capture.In the sea state with water depth of 5.0 m and wave period of 5.0 s,the results of parametric optimization suggest a flap with the width of 8.0 m,thickness of 1.6 m,and with the density as little as possible when the optimum power take-off (PTO) damping coefficient is adopted.

  14. Nearshore Tests of the Tidal Compensation System for Point-Absorbing Wave Energy Converters

    Directory of Open Access Journals (Sweden)

    Valeria Castellucci

    2015-04-01

    Full Text Available The power production of the linear generator wave energy converter developed at Uppsala University is affected by variations of mean sea level. The reason is that these variations change the distance between the point absorber located on the surface and the linear generator located on the seabed. This shifts the average position of the translator with respect to the center of the stator, thereby reducing the generator output power. A device mounted on the point absorber that compensates for tides of small range by regulating the length of the connection line between the buoy at the surface and the linear generator has been constructed and tested. This paper describes the electro-mechanical, measurement, communication and control systems installed on the buoy and shows the results obtained before its connection to the generator. The adjustment of the line was achieved through a linear actuator, which shortens the line during low tides and vice versa. The motor that drives the mechanical device was activated remotely via SMS. The measurement system that was mounted on the buoy consisted of current and voltage sensors, accelerometers, strain gauges and inductive and laser sensors. The data collected were transferred via Internet to a Dropbox server. As described within the paper, after the calibration of the sensors, the buoy was assembled and tested in the waters of Lysekil harbor, a few kilometers from the Uppsala University research site. Moreover, the performance of the sensors, the motion of the mechanical device, the power consumption, the current control strategy and the communication system are discussed.

  15. Analysis of Waves in the Near-Field of Wave Energy Converter Arrays through Stereo Video

    Science.gov (United States)

    Black, C.; Haller, M. C.

    2013-12-01

    Oregon State University conducted a series of laboratory experiments to measure and quantify the near-field wave effects caused within arrays of 3 and 5 Wave Energy Converters (WEC). As the waves and WECs interact, significant scattering and radiation occurs increasing/decreasing the wave heights as well as changing the direction the wave is traveling. These effects may vary based on the number of WECs within an array and their respective locations. The findings of this analysis will assist in selecting the WEC farm location and in improving WEC design. Analyzing the near-field waves will help determine the relative importance of absorption, scattering, and radiation as a function of the incident wave conditions and device performance. The WEC mooring system design specifications may also be impacted if the wave heights in the near-field are greater than expected. It is imperative to fully understand the near-field waves before full-scale WEC farms can be installed. Columbia Power Technologies' Manta served as the test WEC prototype on a 1 to 33 scale. Twenty-three wave gages measured the wave heights in both regular and real sea conditions at locations surrounding and within the WEC arrays. While these gages give a good overall picture of the water elevation behavior, it is difficult to resolve the complicated wave field within the WEC array using point gages. Here stereo video techniques are applied to extract the 3D water surface elevations at high resolution in order to reconstruct the multi-directional wave field in the near-field of the WEC array. The video derived wave information will also be compared against the wave gage data.

  16. Buck-Boost/Forward Hybrid Converter for PV Energy Conversion Applications

    OpenAIRE

    2014-01-01

    This paper presents a charger and LED lighting (discharger) hybrid system with a PV array as its power source for electronic sign indicator applications. The charger adopts buck-boost converter which is operated in constant current mode to charge lead-acid battery and with the perturb and observe method to extract maximum power of PV arrays. Their control algorithms are implemented by microcontroller. Moreover, forward converter with active clamp circuit is operated in voltage regulation cond...

  17. Pre-design of a pendular wave energy converter; Predimensionnement d'un houlo-generateur pendulaire

    Energy Technology Data Exchange (ETDEWEB)

    Ruellan, M.; Rozel, B.; Ben Ahmed, H.; Multon, B. [Ecole nationale Superieure de Cachan, SPEELabs/SATIE, Antenne de Bretagne, 94 (France); Babarit, A.; Clement, A. [Ecole Centrale de Nantes, LMF, UMR CNRS 6598, 44 (France)

    2006-06-15

    This paper presents the principle of an electromagnetic generator pre-design for wave energy converter. We first describe the principle of pendular wave energy converter (WEC) developed in the SEAREV project (Energy Program of CNRS). The behavior of power take off (PTO: the generator) reflects a strong coupling between hydrodynamic, mechanical and electrical phenomena, thus leading to a complex device design problem. We lay out herein a design methodology to be applied on a swell cycle of limited duration, yet which remains representative of the inherent problems raised. We present a simplified optimization approach of the system as well as the first established results, principally in term of laws control. A method of power leveling is also proposed. At last, a pre-design of an electromagnetic permanent magnet generator on a cycle, allowing to satisfy the specifications, is carried out with and without speed multiplier gearbox. (authors)

  18. Output Filter Design for a Novel Dual-Input PV-Wind Power Converter by Energy Balance Principle

    Directory of Open Access Journals (Sweden)

    Chih-Lung Shen

    2016-09-01

    Full Text Available In this paper, a detailed and systematic derivation of the output filter in a novel dual-input photovoltaic (PV-wind converter (DIPWC is presented. The theoretical derivation is based on an energy balance principle. While the DIPWC operates in steady state, the amount of charged energy of the output filter will be equal to that of the energy pumped away within one switching cycle. From this zero net change in energy, the minimum value of the output filter can be found. With the determined value, the DIPWC is able to operate in continuous conduction for high power applications. The developed procedure of the inductance determination can be applied to other types of dual-input converters. Therefore, it makes significant contributions to the design toward a green-energy, multi-input converter. To verify the correctness of the mathematical analysis, the DIPWC—with the derived output inductance—is built and tested. Practical measurements and results have verified the inductance determination.

  19. Multicriteria analysis to evaluate wave energy converters based on their environmental impact: an Italian case study

    Science.gov (United States)

    Azzellino, Arianna; Contestabile, Pasquale; Lanfredi, Caterina; Vicinanza, Diego

    2010-05-01

    The exploitation of renewable energy resources is fast becoming a key objective in many countries. Countries with coastlines have particularly valuable renewable energy resources in the form of tides, currents, waves and offshore wind. Due to the visual impact of siting large numbers of energy generating devices (eg. wind turbines) in terrestrial landscapes, considerable attention is now being directed towards coastal waters. Due to their environmental sensitivity, the selection of the most adequate location for these systems is a critical factor. Multi-criteria analysis allows to consider a wide variety of key characteristics (e.g. water depth, distance to shore, distance to the electric grid in land, geology, environmental impact) that may be converted into a numerical index of suitability for different WEC devices to different locations. So identifying the best alternative between an offshore or a onshore device may be specifically treated as a multicriteria problem. Special enphasisi should be given in the multicriteria analysis to the environmental impact issues. The wave energy prospective in the Italian seas is relatively low if compared to the other European countries faced to the ocean. Based on the wave climate, the Alghero site, (NW Sardinia, Italy) is one of the most interesting sites for the wave energy perspective (about 10 kW/m). Alghero site is characterized by a high level of marine biodiversity. In 2002 the area northern to Alghero harbour (Capo Caccia-Isola Piana) was established a Marine Protected Area (MPA). It could be discussed for this site how to choose between the onshore/offshore WEC alternative. An offshore device like Wave Dragon (http://www.wavedragon.net/) installed at -65m depth (width=300m and length=170 m) may approximately produce about 3.6 GWh/y with a total cost of about 9,000,000 €. On the other hand, an onshore device like SSG (http://waveenergy.no/), employed as crown wall for a vertical breakwater to enlarge the present

  20. Low-pressure hydro turbines and control equipment for wave energy converters (Wave Dragon). Final report

    Energy Technology Data Exchange (ETDEWEB)

    Soerensen, H.C.; Hansen, R.

    2001-06-01

    The Wave Dragon is a 4 MW floating offshore wave energy converter of the overtopping type. Through performing tests on a scale 1:50 model of the Wave Dragon, real-time overtopping time series were provided. These allowed the development of a feasible turbine and regulation strategy for handling the varying heads and flows occurring in the reservoir. A model turbine with a runner diameter of 340 mm was designed, and tested in a conventional turbine test stand. The results revealed very high efficiencies (91.3% peak efficiency), and more importantly a very flat performance curve yielding high turbine efficiency for the complete range of heads available at the Wave Dragon. A suitable power take-off and grid connection system was developed, addressing power quality issues, as well as more practical issues of flexible cabling solutions. It was concluded that feasible solutions to the technical barriers envisioned prior to the project had been found. Also means for improving the overtopping characteristics of the device were put forward. The feasibility of the Wave Dragon at original 1st generation design was investigated and key performance figures were given as net annual power production of 5.1-3.1 GWh/year, 2,775-3,150 Euro/kW in construction costs and a power production price of 0.19-0.27 Euro/kWh. The figures includes availability losses, all losses in the power train, and losses from restricted freedom of movement for two of the scenarios, with a wave energy potential of 16 and 24 kW/m wave front respectively. Significant scope for improvement, especially from enhanced overtopping from improved design, mass production and learning effects were also identified. Through implementing the known technical improvements to the Wave Dragon design identified through the project an annual net power production of 8.9 GWh/year and a production price of 0.12 Euro/kWh is foreseen for a 24 kW/m wave potential. With additional technical improvements, mass production benefits and

  1. Establishment of Motion Model for Wave Capture Buoy and Research on Hydrodynamic Performance of Floating-Type Wave Energy Converter

    Directory of Open Access Journals (Sweden)

    Gao Hongtao

    2015-09-01

    Full Text Available Floating-type wave energy converter has the advantages of high wave energy conversion efficiency, strong shock resistance ability in rough sea and stable output power. So it is regarded as a promising energy utilization facility. The research on hydrodynamic performance of wave capture buoys is the precondition and key to the wave energy device design and optimization. A simplified motion model of the buoys in the waves is established. Based on linear wave theory, the equations of motion of buoys are derived according to Newton’s second law. The factors of wave and buoys structural parameters on wave energy absorption efficiency are discussed in the China’s Bohai Sea with short wave period and small wave height. The results show that the main factor which affects the dynamic responses of wave capture buoys is the proximity of the natural frequency of buoys to the wave period. And the incoming wave power takes a backseat role to it at constant wave height. The buoys structural parameters such as length, radius and immersed depth, influence the wave energy absorption efficiency, which play significant factors in device design. The effectiveness of this model is validated by the sea tests with small-sized wave energy devices. The establishment methods of motion model and analysis results are expected to be helpful for designing and manufacturing of floating-type wave energy converter.

  2. Study of Power Converter Topologies with Energy Recovery and grid power flow control. Part A: 2-quadrant converter with energy storage.

    CERN Document Server

    Maestri, S; Uicich, G; Benedetti, M; Le Godec, G; Papastergiou, K

    2015-01-01

    In the framework of a Transfer line (TT2) Consolidation Programme, a number of studies on Energy cycling have been commissioned. Part of this work involves the study of different power electronic system topologies for magnet energy recovery [1{5]. In this report, the use of a two-quadrant (2Q) regulator connected to the DC link of a 4-quadrant magnet supply is analysed. The key objective of the study is to find control strategies that result in the control of the peak power required from the power network as well as to recover the magnet energy into capacitor banks with controlled voltage fluctuation. The study comprises the modelling of the system by means of the method of state averaging and the development of regulation strategies to energy management. The proposed control strategies can be divided in two groups: in the first group, the magnet current is used to dene the reference for the control system, while in the second group this current is considered as a perturbation and some strategies are devised ...

  3. Buck-Boost/Forward Hybrid Converter for PV Energy Conversion Applications

    Directory of Open Access Journals (Sweden)

    Sheng-Yu Tseng

    2014-01-01

    Full Text Available This paper presents a charger and LED lighting (discharger hybrid system with a PV array as its power source for electronic sign indicator applications. The charger adopts buck-boost converter which is operated in constant current mode to charge lead-acid battery and with the perturb and observe method to extract maximum power of PV arrays. Their control algorithms are implemented by microcontroller. Moreover, forward converter with active clamp circuit is operated in voltage regulation condition to drive LED for electronic sign applications. To simplify the circuit structure of the proposed hybrid converter, switches of two converters are integrated with the switch integration technique. With this approach, the proposed hybrid converter has several merits, which are less component counts, lighter weight, smaller size, and higher conversion efficiency. Finally, a prototype of LED driving system under output voltage of 10 V and output power of 20 W has been implemented to verify its feasibility. It is suitable for the electronic sign indicator applications.

  4. Multipole generator wind energy converter without gearbox and with variable speed

    Energy Technology Data Exchange (ETDEWEB)

    Wortmann, B.; Hansen, L.H.

    2000-01-01

    The idea of this industrial research project was a totally new concept of WTG for NEG Micon A/S. The result has been a multiple range of concepts. Siemens realised a complete design and construction of a multipole PMG generator. However, it was soon recognised that the multipole synchronous PMG concept of Siemens was too expensive. The change to a WRG concept improved the situation. However, it is still doubtful if an economic feasible solution can be obtained for use in a WTG. Evidently, it is necessary looking on other concepts of synchronous generators for wind energy conversion. One way of verifying the economic feasibility was to clarify uncertainty about necessary support technologies. Two support technologies were investigated: variable speed control and blade turning system. Both systems turned out to be interesting concepts on their own. A complete specification of the safety and control strategy for variable speed was developed within this project. The strategy was implemented onthe test WTG on the test site of Risoe National Laboratory. The test set-up is very flexible and is based on the use of a Siemens IGBT Frequency Converter. The WTG can be operated as a conventional stall regulated WTG or as variable speed WTG. For calculation purpose HawC has been enlarged as a first step by the possibility to simulate a stall controlled WTG equipped with an asynchronous generator. Various tests on loads and electrical grid quality can be realised for this case. The second element of the project was the blade turning system, A full scale test set-up made a lifecycle test program possible. Many new tools and valuable knowledge were gathered and developed. The FLEX 4 load calculation program has been adapted to active stall operation. The results of the project were very promising. Today, this research forms the basis for NEG Migon A/S active stall concept on the NM 2000. The project has broaden ed NEG Micon A/S horizon for new control strategies. New areas for

  5. Reliability and Energy Loss in Full-scale Wind Power Converter Considering Grid Codes and Wind Classes

    DEFF Research Database (Denmark)

    Zhou, Dao; Blaabjerg, Frede; Franke, Toke

    2014-01-01

    power converter is studied considering the grid code with reactive power production as well as the annual wind profile. Regarding the reliability, it is found that either the Over-Excited (OE) or the Under-Excited (UE) reactive power injection threatens the lifespan under all wind classes. Meanwhile......, if the specific designed wind turbine system operates at different wind classes, it can be seen that higher wind class level results in lower lifetime of the power converter. In respect to the cost of the reactive power, either the OE or the UE reactive power increases the energy loss per year significantly......With the increasing penetration of the wind power, reliable operation and cost-effective wind energy production are of more and more importance. As one of the promising configurations, the cost on reliability and production losses of permanent-magnet synchronous generator based full-scale wind...

  6. Performance characteristics of a combination solar photovoltaic heat engine energy converter

    Science.gov (United States)

    Chubb, Donald L.

    1987-01-01

    A combination solar photovoltaic heat engine converter is proposed. Such a system is suitable for either terrestrial or space power applications. The combination system has a higher efficiency than either the photovoltaic array or the heat engine alone can attain. Advantages in concentrator and radiator area and receiver mass of the photovoltaic heat engine system over a heat-engine-only system are estimated. A mass and area comparison between the proposed space station organic Rankine power system and a combination PV-heat engine system is made. The critical problem for the proposed converter is the necessity for high temperature photovoltaic array operation. Estimates of the required photovoltaic temperature are presented.

  7. Series Resonant Power Converter for Contactless Energy Transfer with Improved Efficiency

    NARCIS (Netherlands)

    Valtchev, S.S.

    2008-01-01

    The development of more efficient power converters is the most important and challenging task for Power Electronics specialists. In the same time, many currently existing or yet to appear future applications require full mechanical independence between the transmitter and receiver of the electrical

  8. A SVPWM based on fluctuate capacitor voltage in 3L-NPC back-to-back converter applied to wind energy

    DEFF Research Database (Denmark)

    Chen, Quan; Wang, Qunjing; Chen, Zhe

    2014-01-01

    Three-level Neutral-point-clamped (3L-NPC) converters are becoming a realistic alternative to the conventional converters in high-power wind-energy applications. But the unbalance in the supported capacitors' voltage of back-to-back 3L-NPC converters, including the dynamics of the capacitors...... between the fluctuate voltage of upper and lower capacitors is extracted. Based on this error factor the duty-time of every active voltage vector is calculated. In order to validate the model and the control strategy proposed in this paper, a 2MW 3L-NPC converter used in wind energy has been simulated....

  9. 4Nx Non-Isolated and Non-Inverting Hybrid Interleaved Multilevel Boost Converter Based on VLCIm Cell and Cockroft Walton Voltage Multiplier for Renewable Energy Applications

    DEFF Research Database (Denmark)

    Bhaskar, Mahajan Sagar; Padmanaban, Sanjeevikumar; Blaabjerg, Frede

    2016-01-01

    In this treatise, 4Nx hybrid Non Inverting & Non Isolated (NI-NI) DC-DC interleaved multi-level boost converter (4Nx IMBC) for renewable energy applications is proposed. The proposed 4Nx IMBC is derived by coalescing the feature of 2Nx DC-DC Interleaved Multi-level Boost Converter (2Nx IMBC......), voltage-lift-switched-inductor-modified (VLSlm Cell) and Cockcroft Walton (CW) voltage multipliers. The 4Nx converter provides 4N times more conversion voltage ratio compared to conventional boost converter where N denotes the number of output stages of the 4Nx IMBC. To make renewable energy sources...

  10. On the Development of High Power DC-DC Step-Down Converter with Energy Recovery Snubber

    Directory of Open Access Journals (Sweden)

    Alok Singh

    2012-01-01

    Full Text Available The effect of switching losses on the efficiency of a switch mode power converter and methods adopted for its improvement using an energy recovery lossless snubber has been presented. A comparative analysis of various types of soft switching techniques along with effects of dissipative and nondissipative snubbers on efficiency of the converter has been carried out before zeroing in on the selected scheme. The selected snubber serves the dual function of a turn-on and turn-off snubber and thereby reducing the switching losses both during turn-on and turn-off transients, resulting in improved efficiency of the converter. A detailed design procedure of the snubber for high-power applications taking into account various effects such as diode reverse recovery, diode voltage stress, and minimum and maximum duty cycle limits, has been presented in this paper. Importance of practical aspects in layout to minimize wiring inductance is also highlighted. A high-power prototype of buck converter has been developed to experimentally validate the theoretical design and analytical observations.

  11. Mechanosensing and mechanochemical transduction: how is mechanical energy sensed and converted into chemical energy in an extracellular matrix?

    Science.gov (United States)

    Silver, Frederick H; Siperko, Lorraine M

    2003-01-01

    Gravity plays a central role in vertebrate development and evolution. Gravitational forces acting on mammalian tissues cause the net muscle forces required for locomotion to be higher on earth than on a body subjected to a microgravitational field. As body mass increases during development, the musculoskeleton must be able to adapt by increasing the size of its functional units. Thus mechanical forces required to do the work (mechanical energy) of locomotion must be sensed by cells and converted into chemical energy (synthesis of new tissue). Extracellular matrices (ECMs) are multicomponent tissues that transduce internal and external mechanical signals into changes in tissue structure and function through a process termed mechanochemical transduction. Under the influence of an external gravitational field, both mineralized and unmineralized vertebrate tissues exhibit internal tensile forces that serve to preserve a synthetic phenotype in the resident cell population. Application of additional external forces alters the balance between the external gravitational force and internal forces acting on resident cells leading to changes in the expression of genes and production of protein that ultimately may alter the exact structure and function of the extracellular matrix. Changes in the equilibrium between internal and external forces acting on ECMs and changes in mechanochemical transduction processes at the cellular level appear to be important mechanisms by which mammals adjust their needs to store, transmit, and dissipate energy that is required during development and for bodily movements. Mechanosensing is postulated to involve many different cellular and extracellular components. Mechanical forces cause direct stretching of protein-cell surface integrin binding sites that occur on all eukaryotic cells. Stress-induced conformational changes in the extracellular matrix may alter integrin structure and lead to activation of several secondary messenger pathways

  12. Preliminary Verification and Validation of WEC-Sim, an Open-Source Wave Energy Converter Design Tool: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Ruehl, K.; Michelen, C.; Kanner, S.; Lawson, M.; Yu, Y. H.

    2014-03-01

    To promote and support the wave energy industry, a wave energy converter (WEC) design tool, WEC-Sim, is being developed by Sandia National Laboratories and the National Renewable Energy Laboratory. In this paper, the WEC-Sim code is used to model a point absorber WEC designed by the U.S. Department of Energy's reference model project. Preliminary verification was performed by comparing results of the WEC-Sim simulation through a code-to-code comparison, utilizing the commercial codes ANSYS-AQWA, WaveDyn, and OrcaFlex. A preliminary validation of the code was also performed by comparing WEC-Sim simulation results to experimental wave tank tests.

  13. 7.9 pJ/Step Energy-Efficient Multi-Slope 13-bit Capacitance-to-Digital Converter

    KAUST Repository

    Omran, Hesham

    2014-08-01

    In this brief, an energy-efficient capacitance-to-digital converter (CDC) is presented. The proposed CDC uses digitally controlled coarse-fine multi-slope integration to digitize a wide range of capacitance in short conversion time. Both integration current and frequency are scaled, which leads to significant improvement in the energy efficiency of both analog and digital circuitry. Mathematical analysis for circuit nonidealities, noise, and improvement in energy efficiency is provided. A prototype fabricated in a 0.35-μm CMOS process occupies 0.09 mm2 and consumes a total of 153 μA from 3.3 V supply while achieving 13-bit resolution. The operation of the prototype is experimentally verified using MEMS capacitive pressure sensor. Compared to recently published work, the prototype achieves an excellent energy efficiency of 7.9 pJ/Step. © 2004-2012 IEEE.

  14. Controlling backstreaming ions from X-ray converter targets with time varying final focusing solenoidal lens and beam energy variation

    Energy Technology Data Exchange (ETDEWEB)

    Caporaso, G J; Chen, Yu-Jiuan; Paul, A

    1998-08-20

    Backstreaming ions emitted from an x-ray converter hit by a tightly focused intense electron beam can form an ion focusing channel and over-focus the electron beam. As the ions move upstream in time, the net focusing strength increases. The final beam spot size on the target would then change in time and typically be larger than intended. We have developed a model to estimate the backstreaming ions' neutralization factor in a potential sheath near the target surface and away from the sheath. Performance of high resolution x-ray radiography facilities requires high current electron beams to be focused to a millimeter spot size on an x-ray converter through out the entire current pulse. We have studied the possibility of maintaining a constant final spot size for the entire pulse by using either a time varying final focusing solenoid field or beam energy variation to compensate the time varying ion focusing effects

  15. Load estimator-based hybrid controller design for two-interleaved boost converter dedicated to renewable energy and automotive applications.

    Science.gov (United States)

    Bougrine, Mohamed; Benmiloud, Mohammed; Benalia, Atallah; Delaleau, Emmanuel; Benbouzid, Mohamed

    2017-01-01

    This paper is devoted to the development of a hybrid controller for a two-interleaved boost converter dedicated to renewable energy and automotive applications. The control requirements, resumed in fast transient and low input current ripple, are formulated as a problem of fast stabilization of a predefined optimal limit cycle, and solved using hybrid automaton formalism. In addition, a real time estimation of the load is developed using an algebraic approach for online adjustment of the hybrid controller. Mathematical proofs are provided with simulations to illustrate the effectiveness and the robustness of the proposed controller despite different disturbances. Furthermore, a fuel cell system supplying a resistive load through a two-interleaved boost converter is also highlighted.

  16. Modeling and Simulation of a Gallium Nitride (GaN) Betavoltaic Energy Converter

    Science.gov (United States)

    2016-06-01

    technologies, nuclear materials detection, accelerator shielding, and dose/energy deposition in materials for medical therapies . An electron beam with...semiconductor devices have the potential to improve the efficiency of direct energy conversion and indirect energy conversion isotope batteries, making...offering higher- energy-conversion efficiency than 2-dimensional geometries. 15. SUBJECT TERMS GaN, betavoltaic, device simulation, isotope power source

  17. Converter station Timelkam. A new OeBB traction energy supply installation; Umrichterwerk Timelkam. Eine neue Bahnstromversorgungsanlage der OeBB

    Energy Technology Data Exchange (ETDEWEB)

    Baldauf, Hugo [OeBB-Infrastruktur AG, Innsbruck (Austria). Geschaeftsbereich Kraftwerke

    2010-07-15

    As a consequence of upgrading the western main line the traction energy demand increased within the Oberoesterreich region. Therefore, a new feeding point into the OeBB traction power network was required in Oberoesterreich. Therefore, OeBB installed a the new converter station Timelkam containing two converter units having an active power of 30 MW each. The energy is supplied by the 3 AC 110 kV 50 Hz network of Energie AG Oberoesterreich. The new converter station Timelkam was commissioned in October 2009. (orig.)

  18. Technical and Non-Technical Issues towards the Commercialisation of Wave Energy Converters

    DEFF Research Database (Denmark)

    Chozas, Julia Fernandez

    and the synergies in this area with offshore wind energy projects. . v. It studies the benefits of including wave energy in diversified renewable energy systems, chiefly with respect to power output variability and availability. . vi. It evaluates one of the most commonly claimed advantages for the wave energy...... sector: the predictability of waves, and assesses the value of wave forecasting in electricity markets. . vii. Lastly, it reviews the economic assessment of wave energy projects. . The scope of the thesis is broad and embraces subjects that can be categorised within technical and non......-technical disciplines. This combination of findings leads to an overview of the wave energy field and of WEC developments. It underlines hindrances that can affect developments when WECs are commissioned and the benefits wave energy brings to energy systems, especially when wave and wind generation is combined....

  19. Technical and Non-Technical Issues Towards the Commercialisation of Wave Energy Converters

    DEFF Research Database (Denmark)

    Chozas, Julia Fernandez

    it. iv. It investigates the opportunities to grid-connect offshore wave energy projects and the synergies in this area with offshore wind energy projects. v. It studies the benefits of including wave energy in diversified renewable energy systems, chiefly with respect to power output variability...... and availability. vi. It evaluates one of the most commonly claimed advantages for the wave energy sector: the predictability of waves, and assesses the value of wave forecasting in electricity markets. vii. Lastly, it reviews the economic assessment of wave energy projects. The scope of the thesis is broad...... and embraces subjects that can be categorised within technical and non-technical disciplines. This combination of findings leads to an overview of the wave energy field and of WEC developments. It underlines hindrances that can affect developments when WECs are commissioned and the benefits wave energy brings...

  20. Characterization of U.S. Wave Energy Converter (WEC) Test Sites: A Catalogue of Met-Ocean Data.

    Energy Technology Data Exchange (ETDEWEB)

    Dallman, Ann Renee; Neary, Vincent Sinclair

    2014-10-01

    This report presents met - ocean data and wave energy characteristics at three U.S. wave energy converter (WEC) test and potential deployment sites . Its purpose is to enable the compari son of wave resource characteristics among sites as well as the select io n of test sites that are most suitable for a developer's device and that best meet their testing needs and objectives . It also provides essential inputs for the design of WEC test devices and planning WEC tests, including the planning of deployment and op eration s and maintenance. For each site, this report catalogues wave statistics recommended in the (draft) International Electrotechnical Commission Technical Specification (IEC 62600 - 101 TS) on Wave Energy Characterization, as well as the frequency of oc currence of weather windows and extreme sea states, and statistics on wind and ocean currents. It also provides useful information on test site infrastructure and services .

  1. Technical and Non-Technical Issues Towards the Commercialisation of Wave Energy Converters

    DEFF Research Database (Denmark)

    Chozas, Julia Fernandez

    it. iv. It investigates the opportunities to grid-connect offshore wave energy projects and the synergies in this area with offshore wind energy projects. v. It studies the benefits of including wave energy in diversified renewable energy systems, chiefly with respect to power output variability....... As a result, the thesis first identifies the phases that generally appear within WEC developments, it then determines the stages where there is a gap in research, and lastly, it analyses the identified key subjects. Accordingly, the thesis elaborates on seven areas: i. It examines regulatory frameworks...... to energy systems, especially when wave and wind generation is combined....

  2. Novel Interleaved Converter with Extra-High Voltage Gain to Process Low-Voltage Renewable-Energy Generation

    Directory of Open Access Journals (Sweden)

    Chih-Lung Shen

    2016-10-01

    Full Text Available This paper presents a novel interleaved converter (NIC with extra-high voltage gain to process the power of low-voltage renewable-energy generators such as photovoltaic (PV panel, wind turbine, and fuel cells. The NIC can boost a low input voltage to a much higher voltage level to inject renewable energy to DC bus for grid applications. Since the NIC has two circuit branches in parallel at frond end to share input current, it is suitable for high power applications. In addition, the NIC is controlled in an interleaving pattern, which has the advantages that the NIC has lower input current ripple, and the frequency of the ripple is twice the switching frequency. Two coupled inductors and two switched capacitors are incorporated to achieve a much higher voltage gain than conventional high step-up converters. The proposed NIC has intrinsic features such as leakage energy totally recycling and low voltage stress on power semiconductor. Thorough theoretical analysis and key parameter design are presented in this paper. A prototype is built for practical measurements to validate the proposed NIC.

  3. Electro-Mechanical Modeling and Performance Analysis of Floating Wave Energy Converters Utilizing Yo-Yo Vibrating System

    Energy Technology Data Exchange (ETDEWEB)

    Sim, Kyuho; Park, Jisu [Seoul National University, Seoul (Korea, Republic of); Jang, Seon-Jun [Innovation KR, Seoul (Korea, Republic of)

    2015-01-15

    This paper proposes a floating-type wave energy conversion system that consists of a mechanical part (yo-yo vibrating system, motion rectifying system, and power transmission system) and electrical part (power generation system). The yo-yo vibrating system, which converts translational input to rotational motion, is modeled as a single degree-of-freedom system. It can amplify the wave input via the resonance phenomenon and enhance the energy conversion efficiency. The electromechanical model is established from impedance matching of the mechanical part to the electrical system. The performance was analyzed at various wave frequencies and damping ratios for a wave input acceleration of 0.14 g. The maximum output occurred at the resonance frequency and optimal load resistance, where the power conversion efficiency and electrical output power reached 48% and 290 W, respectively. Utilizing the resonance phenomenon was found to greatly enhance the performance of the wave energy converter, and there exists a maximum power point at the optimum load resistance.

  4. Balancing Power Absorption and Fatigue Loads in Irregular Waves for an Oscillating Surge Wave Energy Converter: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Tom, Nathan M.; Yu, Yi-Hsiang; Wright, Alan D.; Lawson, Michael

    2016-06-01

    The aim of this paper is to describe how to control the power-to-load ratio of a novel wave energy converter (WEC) in irregular waves. The novel WEC that is being developed at the National Renewable Energy Laboratory combines an oscillating surge wave energy converter (OSWEC) with control surfaces as part of the structure; however, this work only considers one fixed geometric configuration. This work extends the optimal control problem so as to not solely maximize the time-averaged power, but to also consider the power-take-off (PTO) torque and foundation forces that arise because of WEC motion. The objective function of the controller will include competing terms that force the controller to balance power capture with structural loading. Separate penalty weights were placed on the surge-foundation force and PTO torque magnitude, which allows the controller to be tuned to emphasize either power absorption or load shedding. Results of this study found that, with proper selection of penalty weights, gains in time-averaged power would exceed the gains in structural loading while minimizing the reactive power requirement.

  5. Reliability and Energy Loss in Full-scale Wind Power Converter Considering Grid Codes and Wind Classes

    DEFF Research Database (Denmark)

    Zhou, Dao; Blaabjerg, Frede; Franke, Toke

    2014-01-01

    power converter is studied considering the grid code with reactive power production as well as the annual wind profile. Regarding the reliability, it is found that either the Over-Excited (OE) or the Under-Excited (UE) reactive power injection threatens the lifespan under all wind classes. Meanwhile...... if they are provided all year around, in which the OE reactive power injection even has a worse scenario. Moreover, it is also concluded that in order to realize an energy loss saving of the wind turbine system, the constant power factor control strategy is more preferred compared to an extreme reactive power...... injection....

  6. Sea-state Modification and Heaving Float Interaction Factors from Physical Modelling of Arrays of Wave Energy Converters

    DEFF Research Database (Denmark)

    Stratigaki, Vasiliki; Troch, Peter; Stallard, Tim

    2015-01-01

    Waveenergy converters (WECs) extract energy from ocean waves and have the potential to produce a significant amount of electricity from a renewable resource. However, large “WEC farms” or “WEC arrays” (composed of a large number of individual WECs) are expected to exhibit “WEC array effects...... response, wave induced forces on the WECs, and wave field modifications have been measured. A first understanding of WEC array effects is obtained. This unique experimental set-up of up to 25 individual WEC units in an array layout, placed in a large wave tank, is at present the largest set-up of its kind...

  7. Technical and Non-Technical Issues towards the Commercialisation of Wave Energy Converters

    DEFF Research Database (Denmark)

    Chozas, Julia Fernandez

    and the synergies in this area with offshore wind energy projects. . v. It studies the benefits of including wave energy in diversified renewable energy systems, chiefly with respect to power output variability and availability. . vi. It evaluates one of the most commonly claimed advantages for the wave energy......, it then determines the stages where there is a gap in research, and lastly, it analyses the identified key subjects. Accordingly, the thesis elaborates on seven areas: . i. It examines regulatory frameworks for wave energy developments and how they affect project execution. . ii. It investigates the role...... of stakeholder´s and of the public’s opinion on project’s implementation. iii. It addresses the need to evaluate the power performance of WECs in sea trials, and explains a recently-developed methodology to do it. . iv. It investigates the opportunities to grid-connect offshore wave energy projects...

  8. A Reactive Current Injection Technique for Renewable Energy Converters in Low Voltage Ride-Through Operations

    DEFF Research Database (Denmark)

    Chou, Shih-Feng; Lee, Chia-Tse; Cheng, Po-Tai

    2011-01-01

    Distributed energy resources have assumed an important role in meeting the energy demand of today's world, thanks to their dramatic growth in recent years. Their potential in reducing the green house gas emission also leads to great attentions and expectations. As DERs are integrated into the uti......Distributed energy resources have assumed an important role in meeting the energy demand of today's world, thanks to their dramatic growth in recent years. Their potential in reducing the green house gas emission also leads to great attentions and expectations. As DERs are integrated...

  9. A Reactive Current Injection Technique for Renewable Energy Converters in Low Voltage Ride-Through Operations

    DEFF Research Database (Denmark)

    Chou, Shih-Feng; Lee, Chia-Tse; Cheng, Po-Tai;

    2011-01-01

    Distributed energy resources have assumed an important role in meeting the energy demand of today's world, thanks to their dramatic growth in recent years. Their potential in reducing the green house gas emission also leads to great attentions and expectations. As DERs are integrated into the uti......Distributed energy resources have assumed an important role in meeting the energy demand of today's world, thanks to their dramatic growth in recent years. Their potential in reducing the green house gas emission also leads to great attentions and expectations. As DERs are integrated...

  10. Synthesis and characterization of low work function alkali oxide thin films for unconventional thermionic energy converters

    Science.gov (United States)

    Giorgis, V.; Morini, F.; Zhu, T.; Robillard, J.-F.; Wallart, X.; Codron, J.-L.; Dubois, E.

    2016-11-01

    In this work, we present the synthesis and the characterization of low work function thin films for Micro Thermionic Converters (MTC). The objective is producing a device operating at relatively low temperature (caesium oxides. Our choice to exploit those materials relies on their low work function and their abundance. For both materials, we present the results on the synthesis of the oxides under high vacuum and controlled temperature. The oxide thin films were characterized by X-ray photoelectron spectroscopy, photoemission, and thermionic emission measurements. By exploiting the latter technique, a quantitative evaluation of the current density, emitted by the heated oxides, is obtained as a function of temperature. Our results demonstrate that it is possible to decrease the silicon work function by almost 3 eV, enabling significant thermionic currents despite relatively low temperatures (below 850 K).

  11. Experimental analysis of converters performance of VSI frequency in the energy quality; Analise experimental do desempenho de conversores de frequencia VSI na qualidade de energia

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, Kleiber David; Oliveira, Jose Carlos de; Penna, Cristiane [Universidade Federal de Uberlandia (UFU), MG (Brazil)

    2001-10-15

    This article aims at presenting the results of investigations made in laboratory involving frequency converters performance fed by voltage, PWM sinusoidal type, in relation to the electric energy quality. For that, it was used a commercial converter of the type VSI-PWM fed by a programmable source capable to reproduce disturbances related to the several variable items of energy quality for measurements of spectra of harmonics.

  12. Selection of Design Power of Wave Energy Converters Based on Wave Basin Experiments

    DEFF Research Database (Denmark)

    Martinelli, L.; Zanuttigh, B.; Kofoed, Jens Peter

    2011-01-01

    of the measured efficiency; description of the energy production by means of a function of the design capacity; application of a simple formula for cost benefit analysis. The analyses here proposed are based on the experimental results of 3D tests on two floating wave energy devices, named LEANCON and DEXA...

  13. Introduction Of Wavestar Wave Energy Converters At The Danish Offshore Wind Power Plant Horns Rev 2

    DEFF Research Database (Denmark)

    Marquis, L.; Kramer, Morten; Kringelum, J.

    with this combination. This can increase the value of the produced power from future wind/wave plants. Further potential synergies of combining wind and wave energy in the same area include increased energy production from the available area and sharing of infrastructure costs as well as O&M facilities. In a future...

  14. Screening of Available Tools for Dynamic Mooring Analysis of Wave Energy Converters

    DEFF Research Database (Denmark)

    Thomsen, Jonas Bjerg; Ferri, Francesco; Kofoed, Jens Peter

    2017-01-01

    The focus on alternative energy sources has increased significantly throughout the last few decades, leading to a considerable development in the wave energy sector. In spite of this, the sector cannot yet be considered commercialized, and many challenges still exist, in which mooring of floating...

  15. Computational modeling of pitching cylinder-type ocean wave energy converters using 3D MPI-parallel simulations

    Science.gov (United States)

    Freniere, Cole; Pathak, Ashish; Raessi, Mehdi

    2016-11-01

    Ocean Wave Energy Converters (WECs) are devices that convert energy from ocean waves into electricity. To aid in the design of WECs, an advanced computational framework has been developed which has advantages over conventional methods. The computational framework simulates the performance of WECs in a virtual wave tank by solving the full Navier-Stokes equations in 3D, capturing the fluid-structure interaction, nonlinear and viscous effects. In this work, we present simulations of the performance of pitching cylinder-type WECs and compare against experimental data. WECs are simulated at both model and full scales. The results are used to determine the role of the Keulegan-Carpenter (KC) number. The KC number is representative of viscous drag behavior on a bluff body in an oscillating flow, and is considered an important indicator of the dynamics of a WEC. Studying the effects of the KC number is important for determining the validity of the Froude scaling and the inviscid potential flow theory, which are heavily relied on in the conventional approaches to modeling WECs. Support from the National Science Foundation is gratefully acknowledged.

  16. Single-fiber-based hybridization of energy converters and storage units using graphene as electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Joonho; Lee, Minbaek; Wang, Zhong Lin [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA (United States); Park, Young Jun; Cha, Seung Nam; Kim, Jong Min [Frontier Research Lab, Samsung Advanced Institute of Technology, Samsung Electronics, Gyeonggi-Do (Korea, Republic of); Choi, Young Jin [Department of Physics, MyongJi University, Yongin (Korea, Republic of); Department of Nano Science and Engineering, MyongJi University, Yongin (Korea, Republic of); Lee, Churl Seung [Energy Nanomaterials Research Center, Korea Electronics Technology Institute, 68 Yatap-dong, Bundang-gu, Seongnam-si, Gyeonggi-do (Korea, Republic of)

    2011-08-09

    The first integration of multiple energy harvesters and a storage device along single fiber using ZnO nanowires (NWs) and graphenes as the basic materials is reported. This energy generation and storage device allows simultaneous harvesting of solar and mechanical energy. The unique architecture of fiber-based electrodes and use of ZnO NWs, and graphenes as active material and electrodes could be useful for the future development of flexible and wearable electronics. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. An Open-Access COE Calculation tool for Wave Energy Converters

    DEFF Research Database (Denmark)

    2013-01-01

    Aalborg University together with Energinet.dk, the Danish Transmission System Operator, have released a freely available online spreadsheet to evaluate the Levelised Cost of Energy (LCOE) for wave energy projects. The open-access tool calculates the LCOE based on the power production of a Wave...... this is conceived as an open-access tool, available to device developers as well as academia. It can eventually help in the development of wave energy by contributing to open talks with investors, stakeholders, politicians and the general public....

  18. Risk-based Operation and Maintenance Approach for Wave Energy Converters Taking Weather Forecast Uncertainties into Account

    DEFF Research Database (Denmark)

    Ambühl, Simon; Kramer, Morten Mejlhede; Sørensen, John Dalsgaard

    2016-01-01

    Inspection and maintenance costs are significant contributors to the cost of energy for wave energy converters. Maintenance can be performed after failure (corrective) or before a breakdown (preventive) occurs. Furthermore, helicopter and boat can be used to transport equipment and personnel...... to the device for operation and maintenance actions. This article focusses on a risk-based inspection and maintenance planning approach involving minimization of the overall repair costs including costs due to lost electricity production. The study includes real weather data and damage accumulation as well...... as uncertainties related with imperfect weather forecasts, costs, structural damage accumulation, inspection accuracy and the applied maintenance strategies. This article contains a case study where the risk-based maintenance strategy is applied for the Wavestar device....

  19. Balancing Power Absorption and Structural Loading for an Assymmetric Heave Wave-Energy Converter in Regular Waves: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Tom, Nathan M.; Madhi, Farshad; Yeung, Ronald W.

    2016-07-01

    The aim of this paper is to maximize the power-to-load ratio of the Berkeley Wedge: a one-degree-of-freedom, asymmetrical, energy-capturing, floating breakwater of high performance that is relatively free of viscosity effects. Linear hydrodynamic theory was used to calculate bounds on the expected time-averaged power (TAP) and corresponding surge restraining force, pitch restraining torque, and power take-off (PTO) control force when assuming that the heave motion of the wave energy converter remains sinusoidal. This particular device was documented to be an almost-perfect absorber if one-degree-of-freedom motion is maintained. The success of such or similar future wave energy converter technologies would require the development of control strategies that can adapt device performance to maximize energy generation in operational conditions while mitigating hydrodynamic loads in extreme waves to reduce the structural mass and overall cost. This paper formulates the optimal control problem to incorporate metrics that provide a measure of the surge restraining force, pitch restraining torque, and PTO control force. The optimizer must now handle an objective function with competing terms in an attempt to maximize power capture while minimizing structural and actuator loads. A penalty weight is placed on the surge restraining force, pitch restraining torque, and PTO actuation force, thereby allowing the control focus to be placed either on power absorption or load mitigation. Thus, in achieving these goals, a per-unit gain in TAP would not lead to a greater per-unit demand in structural strength, hence yielding a favorable benefit-to-cost ratio. Demonstrative results in the form of TAP, reactive TAP, and the amplitudes of the surge restraining force, pitch restraining torque, and PTO control force are shown for the Berkeley Wedge example.

  20. Balancing Power Absorption and Structural Loading for an Asymmetric Heave Wave-Energy Converter in Regular Waves

    Energy Technology Data Exchange (ETDEWEB)

    Tom, Nathan M.; Madhi, Farshad; Yeung, Ronald W.

    2016-06-24

    The aim of this paper is to maximize the power-to-load ratio of the Berkeley Wedge: a one-degree-of-freedom, asymmetrical, energy-capturing, floating breakwater of high performance that is relatively free of viscosity effects. Linear hydrodynamic theory was used to calculate bounds on the expected time-averaged power (TAP) and corresponding surge restraining force, pitch restraining torque, and power take-off (PTO) control force when assuming that the heave motion of the wave energy converter remains sinusoidal. This particular device was documented to be an almost-perfect absorber if one-degree-of-freedom motion is maintained. The success of such or similar future wave energy converter technologies would require the development of control strategies that can adapt device performance to maximize energy generation in operational conditions while mitigating hydrodynamic loads in extreme waves to reduce the structural mass and overall cost. This paper formulates the optimal control problem to incorporate metrics that provide a measure of the surge restraining force, pitch restraining torque, and PTO control force. The optimizer must now handle an objective function with competing terms in an attempt to maximize power capture while minimizing structural and actuator loads. A penalty weight is placed on the surge restraining force, pitch restraining torque, and PTO actuation force, thereby allowing the control focus to be placed either on power absorption or load mitigation. Thus, in achieving these goals, a per-unit gain in TAP would not lead to a greater per-unit demand in structural strength, hence yielding a favorable benefit-to-cost ratio. Demonstrative results in the form of TAP, reactive TAP, and the amplitudes of the surge restraining force, pitch restraining torque, and PTO control force are shown for the Berkeley Wedge example.

  1. Synthesis of Numerical Methods for Modeling Wave Energy Converter-Point Absorbers: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Li, Y.; Yu, Y. H.

    2012-05-01

    During the past few decades, wave energy has received significant attention among all ocean energy formats. Industry has proposed hundreds of prototypes such as an oscillating water column, a point absorber, an overtopping system, and a bottom-hinged system. In particular, many researchers have focused on modeling the floating-point absorber as the technology to extract wave energy. Several modeling methods have been used such as the analytical method, the boundary-integral equation method, the Navier-Stokes equations method, and the empirical method. However, no standardized method has been decided. To assist the development of wave energy conversion technologies, this report reviews the methods for modeling the floating-point absorber.

  2. Organic thermoelectric materials: emerging green energy materials converting heat to electricity directly and efficiently.

    Science.gov (United States)

    Zhang, Qian; Sun, Yimeng; Xu, Wei; Zhu, Daoben

    2014-10-29

    The abundance of solar thermal energy and the widespread demands for waste heat recovery make thermoelectric generators (TEGs) very attractive in harvesting low-cost energy resources. Meanwhile, thermoelectric refrigeration is promising for local cooling and niche applications. In this context there is currently a growing interest in developing organic thermoelectric materials which are flexible, cost-effective, eco-friendly and potentially energy-efficient. In particular, the past several years have witnessed remarkable progress in organic thermoelectric materials and devices. In this review, thermoelectric properties of conducting polymers and small molecules are summarized, with recent progresses in materials, measurements and devices highlighted. Prospects and suggestions for future research efforts are also presented. The organic thermoelectric materials are emerging candidates for green energy conversion.

  3. Influence of crystalline orientation on the thermal-energy convertion efficiency in shape memory alloys

    Directory of Open Access Journals (Sweden)

    Cortés-Pérez J.

    2014-01-01

    Full Text Available A theoretical study about the influence of crystalline orientation on the energy conversion efficiency of two shape memory alloys is present. The study consider single crystal samples in simple tension. The results showed higher properties for of the NiTi than Cu-Al-Be, especially in the temperature-increment (ΔT necessary for get a conversion energy cycle. However, the study showed a crystalline orientation favorable for Cu-Al-Be.

  4. Second life battery energy storage systems:converter topology and redundancy selection

    OpenAIRE

    Mukherjee, N.; Strickland, D

    2014-01-01

    Battery energy storage systems have traditionally been manufactured using new batteries with a good reliability. The high cost of such a system has led to investigations of using second life transportation batteries to provide an alternative energy storage capability. However, the reliability and performance of these batteries is unclear and multi-modular power electronics with redundancy have been suggested as a means of helping with this issue. This paper reviews work already undertaken on ...

  5. FPGA-based real-time simulation of power converters of renewable energy sources

    Energy Technology Data Exchange (ETDEWEB)

    Kokenyesi, Tamas; Varjasi, Istvan [Budapest University of Technology and Economics, Department of Automation and Applied Informatics (Hungary)], e-mail: kokenyesi.tamas@gmail.com, email: varjasi@aut.bme.hu

    2011-07-01

    This paper presents a hardware-in-the-loop testing (HIL) approach based on a field programmable gate array (FPGA) real-time simulation with real measured signals designed to reduce the cost and time for testing the main circuit of a power converter significantly. This method allows the control unit to measure its outputs on the same signal level in a completely transparent way, unlike other computer based simulation methods. As an example, a simulator for a three-phase inverter used for DC/AC conversion or frequency control is described and the simulated network illustrated. The calculation procedure and relative equations are also detailed, with simulation parameters and some measurement results being presented. It was found that the main advantage of this method is speed, which was only limited by the actual capabilities of the FPGA used. This method can be applied to a wide variety of analog circuits, reducing time to market. More complex circuits and higher frequencies could be simulated in the future with the evolution of FPGAs.

  6. New generation polyphase resonant converter-modulators for the Korean atomic energy research institute

    Energy Technology Data Exchange (ETDEWEB)

    Reass, William A [Los Alamos National Laboratory; Baca, David M [Los Alamos National Laboratory; Gribble, Robert F [Los Alamos National Laboratory

    2009-01-01

    This paper will present operational data and performance parameters of the newest generation polyphase resonant high voltage converter modulator (HVCM) as developed and delivered to the KAERI 100 MeV ''PEFP'' accelerator [1]. The KAERI design realizes improvements from the SNS and SLAC designs [2]. To improve the IGBT switching performance at 20 kHz for the KAERI system, the HVCM utilizes the typical zero-voltage-switching (ZVS) at turn on and as well as artificial zero-current-switching (ZCS) at turn-off. The new technique of artificial ZCS technique should result in a 6 fold reduction of IGBT switching losses (3). This improves the HCVM conversion efficiency to better than 95% at full average power, which is 500 kW for the KAERI two klystron 105 kV, 50 A application. The artificial ZCS is accomplished by placing a resonant RLC circuit across the input busswork to the resonant boost transformer. This secondary resonant circuit provides a damped ''kick-back'' to assist in IGBT commutation. As the transformer input busswork is extremely low inductance (< 10 nH), the single RLC network acts like it is across each of the four IGBT collector-emitter terminals of the H-bridge switching network. We will review these topological improvements and the overall system as delivered to the KAERI accelerator and provide details of the operational results.

  7. A Particle-in-Cell Simulation for the Traveling Wave Direct Energy Converter (TWDEC) for Fusion Propulsion

    Science.gov (United States)

    Chap, Andrew; Tarditi, Alfonso G.; Scott, John H.

    2013-01-01

    A Particle-in-cell simulation model has been developed to study the physics of the Traveling Wave Direct Energy Converter (TWDEC) applied to the conversion of charged fusion products into electricity. In this model the availability of a beam of collimated fusion products is assumed; the simulation is focused on the conversion of the beam kinetic energy into alternating current (AC) electric power. The model is electrostatic, as the electro-dynamics of the relatively slow ions can be treated in the quasistatic approximation. A two-dimensional, axisymmetric (radial-axial coordinates) geometry is considered. Ion beam particles are injected on one end and travel along the axis through ring-shaped electrodes with externally applied time-varying voltages, thus modulating the beam by forming a sinusoidal pattern in the beam density. Further downstream, the modulated beam passes through another set of ring electrodes, now electrically oating. The modulated beam induces a time alternating potential di erence between adjacent electrodes. Power can be drawn from the electrodes by connecting a resistive load. As energy is dissipated in the load, a corresponding drop in beam energy is measured. The simulation encapsulates the TWDEC process by reproducing the time-dependent transfer of energy and the particle deceleration due to the electric eld phase time variations.

  8. Modelling Of Converter Characteristics of Wind Energy Conversion System during Voltage Sags

    Directory of Open Access Journals (Sweden)

    Pratyusha Dikkala,

    2014-01-01

    Full Text Available The proposed system presents power-control strategies of a grid-connected hybrid generation system with versatile power transfer. This hybrid system allows maximum utilization of freely available renewable energy sources like wind and photovoltaic energies. For this, an adaptive maximum power point tracking (MPPT algorithm along with standard perturbs and observe method will be used for the system. The turbine rotor speed is the main determinant of mechanical output from wind energy and Solar cell operating voltage in the case of output power from solar energy. Permanent Magnet Synchronous Generator is coupled with wind turbine for attaining wind energy conversion system. This paper addresses dynamic modeling and control of a grid-connected wind–PV–battery hybrid system with versatile power transfer. The hybrid system, unlike conventional systems, considers the stability and dispatch-ability of its power injection into the grid. The hybrid system can operate in three different modes, which include normal operation without use of battery, dispatch operation, and averaging operation. This paper also indicates the merits of the proposed system.

  9. Preliminary Results from Second Phase Sea Testing of the Wave Dragon Prototype Wave Energy Converter

    DEFF Research Database (Denmark)

    Soerensen, Hans Chr.; Tedd, James; Friis-Madsen, Erik;

    2006-01-01

    In March 2006 the prototype Wave Dragon has been redeployed to a more energetic site in Nissum Bredning an inland sea in Western Denmark. This has followed a period of renovation of many aspects of the device which have resulted in 20% higher energy output. This paper describes the preliminary re...

  10. Designing New Materials for Converting Solar Energy to Fuels via Quantum Mechanics

    Science.gov (United States)

    2014-07-11

    grant was the first to the PI to use first principles quantum mechanics to characterize key atomic-scale elementary processes involved in photocatalysis ...free energies for reduction and oxidation determines whether photocatalysis is thermodynamically allowed. • Finally, we calculate surface redox... photocatalysis , given its improved conductivity properties compared to hematite. Summary Concepts and findings developed during this grant were

  11. Preliminary Results from Second Phase Sea Testing of the Wave Dragon Prototype Wave Energy Converter

    DEFF Research Database (Denmark)

    Soerensen, Hans Chr.; Tedd, James; Friis-Madsen, Erik

    2006-01-01

    In March 2006 the prototype Wave Dragon has been redeployed to a more energetic site in Nissum Bredning an inland sea in Western Denmark. This has followed a period of renovation of many aspects of the device which have resulted in 20% higher energy output. This paper describes the preliminary...

  12. Single-Switch Equalization Charger Using Multiple Stacked Buck-Boost Converters for Series-Connected Energy-Storage Modules

    Science.gov (United States)

    Uno, Masatoshi; Tanaka, Koji

    Series connections of energy-storage modules such as electric double-layer capacitors (EDLCs) and lithium-ion batteries result in voltage imbalance because of the nonuniform properties of individual modules. Conventional voltage equalizers based on traditional dc-dc converters require numerous switches and/or transformers, and therefore, their costs and complexity tend to increase. This paper proposes a novel single-switch equalization charger using multiple stacked buck-boost converters. The single-switch operation not only reduces the circuit complexity but also contributes to increasing the reliability. The fundamental operating principles and design procedures of key components are presented in detail. An experimental charge test using a 25W prototype of the proposed equalization charger was performed for four series-connected EDLC modules whose initial voltages were intentionally imbalanced. Experimental results demonstrated that the proposed equalization charger could charge the series-connected modules preferentially in the order of increasing module voltage and that all the modules could be charged up to a uniform voltage level.

  13. Influence of the excitation force estimator methodology within a predictive controller framework on the overall cost of energy minimisation of a wave energy converter

    DEFF Research Database (Denmark)

    Ferri, Francesco; Ambühl, Simon; Kofoed, Jens Peter

    2015-01-01

    is linked to the cost of the energy (CoE) produced from the different wave energy converters (WEC). The CoE from the different WECs is not yet comparable with other energy resources, due to a relative low efficiency coupled with the high structural costs. Within the sector a large effort has been addressed......, the application of an advance control strategy will most probably increase the loads exerted on the structure, leading to an increment of the structural cost. Therefore, the problem of minimising the CoE produced by a WEC is at least a 2Dproblem. In a previous article [3], the minimisation problem has been...... was implemeted with perfect knowledge of the future loadtime series, which is physically not achivable. This article is an extension of the work presented in [3] with a closer focus on the infuence of the excitation force prediction on the capability of the MPC architecture. Different estimator models...

  14. Design of full scale wave simulator for testing Power Take Off systems for wave energy converters

    DEFF Research Database (Denmark)

    Pedersen, H. C.; Hansen, R. H.; Hansen, Anders Hedegaard

    2016-01-01

    For wave energy to become a major future contributor of renewable energy it is a requirement that the efficiency and reliability of the Power Take-Off (PTO) systems is significantly improved. However, the cost of installing and testing PTO-systems at sea is very high. The focus of the current paper...... is therefore on the design and commissioning of a full scale wave simulator for testing PTO-systems for point absorbers. The challenge is to be able to design a system, which mimics the behavior of a wave when interacting with a given PTO-system – especially when considering discrete type PTO......-systems. The paper presents the designed system, including the major design considerations. A model of the complete system is presented and controllers for the system are developed. These enable the system to emulate the wave behavior and the wave–float interaction. Finally both simulation and experimental results...

  15. Investigation of Wave Energy Converter Effects on the Nearshore Environment: A Month-Long Study in Monterey Bay CA.

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, Jesse D.; Chang, Grace; Magalen, Jason; Jones, Craig

    2014-09-01

    A modified version of an indust ry standard wave modeling tool, SNL - SWAN, was used to perform model simulations for hourly initial wave conditio ns measured during the month of October 2009. The model was run with an array of 50 wave energy converters (WECs) and compared with model runs without WECs. Maximum changes in H s were found in the lee of the WEC array along the angles of incident wave dire ction and minimal changes were found along the western side of the model domain due to wave shadowing by land. The largest wave height reductions occurred during observed typhoon conditions and resulted in 14% decreases in H s along the Santa Cruz shoreline . Shoreline reductions in H s were 5% during s outh swell wave conditions and negligible during average monthly wave conditions.

  16. Investigation of Wave Energy Converter Effects on Near-shore Wave Fields: Model Generation Validation and Evaluation - Kaneohe Bay HI.

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, Jesse D.; Chang, Grace; Jones, Craig

    2014-09-01

    The numerical model, SWAN (Simulating WAves Nearshore) , was used to simulate wave conditions in Kaneohe Bay, HI in order to determine the effects of wave energy converter ( WEC ) devices on the propagation of waves into shore. A nested SWAN model was validated then used to evaluate a range of initial wave conditions: significant wave heights (H s ) , peak periods (T p ) , and mean wave directions ( MWD) . Differences between wave height s in the presence and absence of WEC device s were assessed at locations in shore of the WEC array. The maximum decrease in wave height due to the WEC s was predicted to be approximately 6% at 5 m and 10 m water depths. Th is occurred for model initiation parameters of H s = 3 m (for 5 m water depth) or 4 m (10 m water depth) , T p = 10 s, and MWD = 330deg . Subsequently, bottom orbital velocities were found to decrease by about 6%.

  17. Investigation of Wave Energy Converter Effects on Wave Fields: A Modeling Sensitivity Study in Monterey Bay CA.

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, Jesse D.; Grace Chang; Jason Magalen; Craig Jones

    2014-08-01

    A n indust ry standard wave modeling tool was utilized to investigate model sensitivity to input parameters and wave energy converter ( WEC ) array deploym ent scenarios. Wave propagation was investigated d ownstream of the WECs to evaluate overall near - and far - field effects of WEC arrays. The sensitivity study illustrate d that b oth wave height and near - bottom orbital velocity we re subject to the largest pote ntial variations, each decreas ed in sensitivity as transmission coefficient increase d , as number and spacing of WEC devices decrease d , and as the deployment location move d offshore. Wave direction wa s affected consistently for all parameters and wave perio d was not affected (or negligibly affected) by varying model parameters or WEC configuration .

  18. FPGA-based Time to Digital Converter and Data Acquisition system for High Energy Tagger of KLOE-2 experiment

    CERN Document Server

    Iafolla, L; Beretta, M; Ciambrone, P; Gatta, M; Gonnella, F; Mascolo, M; Messi, R; Moricciani, D; Riondino, D

    2012-01-01

    In order to reconstruct gamma-gamma physics events tagged with High Energy Tagger (HET) in the KLOE-2 (K LOng Experiment 2), we need to measure the Time Of Flight (TOF) of the electrons and positrons from the KLOE-2 Interaction Point (IP) to our tagging stations (11 m apart). The required resolution must be better than the bunch spacing (2.7 ns). We have developed and implemented on a Xilinx Virtex-5 FPGA a Time to Digital Converter (TDC) with 625 ps resolution (LSB) along with an embedded data acquisition system and the interface to the online FARM of KLOE-2. We will describe briefly the architecture of the TDC and of the Data AcQuisition (DAQ) system. Some more details will be provided about the zero-suppression algorithm used to reduce the data throughput.

  19. Wave Energy Converter Effects on Wave Fields: Evaluation of SNL-SWAN and Sensitivity Studies in Monterey Bay CA.

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, Jesse D.; Chang, Grace; Magalen, Jason; Jones, Craig

    2014-09-01

    A modified version of an indust ry standard wave modeling tool was evaluated, optimized, and utilized to investigate model sensitivity to input parameters a nd wave energy converter ( WEC ) array deployment scenarios. Wave propagation was investigated d ownstream of the WECs to evaluate overall near - and far - field effects of WEC arrays. The sensitivity study illustrate d that wave direction and WEC device type we r e most sensitive to the variation in the model parameters examined in this study . Generally, the changes in wave height we re the primary alteration caused by the presence of a WEC array. Specifically, W EC device type and subsequently their size directly re sult ed in wave height variations; however, it is important to utilize ongoing laboratory studies and future field tests to determine the most appropriate power matrix values for a particular WEC device and configuration in order to improve modeling results .

  20. Comparison of the Experimental and Numerical Results of Modelling a 32-Oscillating Water Column (OWC, V-Shaped Floating Wave Energy Converter

    Directory of Open Access Journals (Sweden)

    John V. Ringwood

    2013-08-01

    Full Text Available Combining offshore wind and wave energy converting apparatuses presents a number of potentially advantageous synergies. To facilitate the development of a proposed floating platform combining these two technologies, proof of concept scale model testing on the wave energy converting component of this platform has been conducted. The wave energy component is based on the well-established concept of the oscillating water column. A numerical model of this component has been developed in the frequency domain, and the work presented here concerns the results of this modelling and testing. The results of both are compared to assess the validity and usefulness of the numerical model.

  1. Short term wave forecasting, using digital filters, for improved control of Wave Energy Converters

    DEFF Research Database (Denmark)

    Tedd, James; Frigaard, Peter

    2007-01-01

    experimentally. Results are shown form measurements taken on the Wave Dragon prototype device, a floating overtopping device situated in Northern Denmark. In this case the method is able to accurately predict the surface elevation at the device 11.2 seconds before the measurement is made. This is sufficient......This paper presents a Digital Filter method for real time prediction of waves incident upon a Wave Energy device. The method transforms waves measured at a point ahead of the device, to expected waves incident on the device. The relationship between these incident waves and power capture is derived...

  2. Optimal Discrete PTO Force Point Absorber Wave Energy Converters in Regular Waves

    DEFF Research Database (Denmark)

    Hansen, Anders Hedegaard; Pedersen, Henrik C.

    2013-01-01

    the conventional fluid power systems suffer of poor efficiency. Therefore discrete fluid power force systems have been proposed. Limited research has, however, been conducted with focus on choosing the discrete force levels and force profiles for a discrete PTO system for WECs. This paper is to support the design...... of discrete force systems for PTO, by focusing on how to choose the optimal PTO force levels and force profile when seeking to increase energy harvesting. The work concerns point absorber WECs and utilises a simple float model based on linear wave theory. Utilising the principle of superposition...

  3. Dynamic Model and Control of a New Underwater Three-Degree-of-Freedom Tidal Energy Converter

    Directory of Open Access Journals (Sweden)

    José A. Somolinos

    2015-01-01

    Full Text Available There is currently a growing interest in developing devices that can be used to exploit energy from oceans. In the recent past, the search for oil and gas at ever-greater depths has led to the evolution of devices with which these resources are extracted. These devices range from those that simply rest on the seabed to those that are fully floating and anchored to it. This trend can be considered as the basis needed to understand the future evolution of devices for harnessing depth renewable resources. This paper presents a simple dynamic modeling and a nonlinear multivariable control model-based system for a new three-degree-of-freedom underwater generator with which energy from depth marine currents is harnessed when reference trajectory tracking for the emersion maneuvers needed to carry out maintenance tasks is performed. The goodness of both the model and the proposed controller has been demonstrated through the development of various simulations in the MATLAB-Simulink environment. Additionally, the validation of the control algorithms was carried out by using the dynamic model offered by the simulation environment Orcina OrcaFlex (software for the dynamic analysis for offshore marine systems through the MATLAB-OrcaFlex interface.

  4. An enhanced role for an energy storage system in a microgrid with converter-interfaced sources

    Directory of Open Access Journals (Sweden)

    Konstantinos O. Oureilidis

    2014-12-01

    Full Text Available An enhanced role for the energy storage system (ESS, strategically placed at the point of common coupling (PCC of the microgrid with the utility grid, is proposed. During island operation, the ESS ensures that the frequency and magnitude of the voltage will remain within the limits specified by the Standard EN 50160. By implementing an adjustable droop control method, the distributed energy resources (DERs adjust their active and reactive powers in order to fulfil the load demand. When the grid is recovered, the ESS detects its presence and achieves a seamless synchronisation of the microgrid with the main grid, without any kind of communication. In grid-connected mode, the DERs deliver their available active power, whereas their reactive power is determined by a zero-sequence voltage. This voltage is injected by the ESS and aims to the zeroing of the amount of reactive power at the PCC. In this way, a reduction of power losses in the distribution lines of the microgrid is achieved. The effectiveness of the proposed control method in all operation modes, without any physical communication means, is demonstrated through detailed simulation in a representative microgrid with DERs fed by photovoltaics.

  5. Converting campus waste into renewable energy - a case study for the University of Cincinnati.

    Science.gov (United States)

    Tu, Qingshi; Zhu, Chao; McAvoy, Drew C

    2015-05-01

    This paper evaluates the implementation of three waste-to-energy projects at the University of Cincinnati: waste cooking oil-to-biodiesel, waste paper-to-fuel pellets and food waste-to-biogas, respectively. The implementation of these waste-to-energy (WTE) projects would lead to the improvement of campus sustainability by minimizing waste management efforts and reducing GHG emissions via the displacement of fossil fuel usage. Technical and economic aspects of their implementation were assessed and the corresponding GHG reduction was estimated. Results showed that on-site implementation of these projects would: (1) divert 3682L (974 gallons) of waste cooking oil to 3712L (982 gallons) of biodiesel; (2) produce 138tonnes of fuel pellets from 133tonnes of waste paper (with the addition of 20.75tonnes of plastics) to replace121tonnes of coal; and (3) produce biogas that would be enough to replace 12,767m(3) natural gas every year from 146tonnes of food waste. The economic analysis determined that the payback periods for the three projects would be 16months for the biodiesel, 155months for the fuel pellet, and 74months for the biogas projects. The reduction of GHG emission from the implementation of the three WTE projects was determined to be 9.37 (biodiesel), 260.49 (fuel pellets), and 11.36 (biogas) tonnes of CO2-eq per year, respectively. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Mechanical design and modeling of a single-piston pump for the novel power take-off system of a wave energy converter

    NARCIS (Netherlands)

    Vakis, Antonis I.; Anagnostopoulos, John S.

    2016-01-01

    A multi-pump, multi-piston power take-off wave energy converter ((MPPTO)-P-2 WEC) has been proposed for use with a novel renewable energy harvester termed the Ocean Grazer. The (MPPTO)-P-2 WEC utilizes wave motion to pump via buoys connected to pistons working fluid within a closed circuit and store

  7. Modelling and Testing of Wave Dragon Wave Energy Converter Towards Full Scale Deployment

    DEFF Research Database (Denmark)

    Parmeggiani, Stefano

    -commercial stage in which it has proven difficult to secure the necessary funding for the deployment of a full-scale demonstrator unit. The work presented aims at easing this process, by increasing public and scientific knowledge of the device, as well as by showing the latest progress in its development. Research....... This is mainly due to the development of an updated overtopping model specifically suited to Wave Dragon, which allows greater quality to predictions of the primary energy absorption of the device compared to previous versions. At the same time an equitable approach has been described and used in the performance......, the research has also provided a deeper insight into the physics of the overtopping process by individually assessing the influence of related device configuration and wave features, which goes beyond the present application and may be used for other overtopping WECs as well. Comprehensive analysis...

  8. Short term wave forecasting, using digital filters, for improved control of Wave Energy Converters

    Energy Technology Data Exchange (ETDEWEB)

    Tedd, J.; Frigaard, P. [Department of Civil Engineering, Aalborg University, Aalborg (Denmark)

    2007-07-01

    This paper presents a Digital Filter method for real time prediction of waves incident upon a Wave Energy device. The method transforms waves measured at a point ahead of the device, to expected waves incident on the device. The relationship between these incident waves and power capture is derived experimentally. Results are shown form measurements taken on the Wave Dragon prototype device, a floating overtopping device situated in Northern Denmark. In this case the method is able to accurately predict the surface elevation at the device 11.2 seconds before the measurement is made. This is sufficient to allow advanced control systems to be developed using this knowledge to significantly improve power capture.

  9. Performance Assessment of the Wave Dragon Wave Energy Converter Based on the EquiMar Methodology

    DEFF Research Database (Denmark)

    Parmeggiani, Stefano; Chozas, Julia Fernandez; Pecher, Arthur

    2011-01-01

    At the present pre-commercial phase of the wave energy sector, device developers are called to provide reliable estimates on power performance and production at possible deployment locations. The EU EquiMar project has proposed a novel approach, where the performance assessment is based mainly...... on experimental data deriving from sea trials rather than solely on numerical predictions. The study applies this methodology to evaluate the performance of Wave Dragon at two locations in the North Sea, based on the data acquired during the sea trials of a 1:4.5 scale prototype. Indications about power...... performance and production of the device at the target locations, as well as on the applicability of the methodology, are provided....

  10. Modeling and control in Nissum. Technical report; Wave energy converter Wave Star

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, E.V.

    2009-09-15

    The purpose of this report is to give a deeper theoretical understanding of the achieved results of the performance tests described in another report. It is documented that the 2nd generation of PTO (Power Take-Off) is able to absorb significantly more energy than the existing PTO. 1) A linear dynamic model of the PTO in Nissum is derived and analogies to the electrical circuits are drawn. 2) A deeper mathematical and physical insight on the control strategy with the 2nd generation of PTO is given. 3) The 2nd generation of PTO is equivalent to create a resistive load which matches the intrinsic resistance of the system (resistance matching). 4) The performed simulations agree with the experiments realized in the actual performance tests where it is concluded that 2nd generation of PTO has a higher performance. (LN)

  11. Technological cost-reduction pathways for attenuator wave energy converters in the marine hydrokinetic environment.

    Energy Technology Data Exchange (ETDEWEB)

    Bull, Diana L; Ochs, Margaret Ellen

    2013-09-01

    This report considers and prioritizes the primary potential technical costreduction pathways for offshore wave activated body attenuators designed for ocean resources. This report focuses on technical research and development costreduction pathways related to the device technology rather than environmental monitoring or permitting opportunities. Three sources of information were used to understand current cost drivers and develop a prioritized list of potential costreduction pathways: a literature review of technical work related to attenuators, a reference device compiled from literature sources, and a webinar with each of three industry device developers. Data from these information sources were aggregated and prioritized with respect to the potential impact on the lifetime levelized cost of energy, the potential for progress, the potential for success, and the confidence in success. Results indicate the five most promising costreduction pathways include advanced controls, an optimized structural design, improved power conversion, planned maintenance scheduling, and an optimized device profile.

  12. Note: A cubic electromagnetic harvester that convert vibration energy from all directions.

    Science.gov (United States)

    Han, Mengdi; Qiu, Guolin; Liu, Wen; Meng, Bo; Zhang, Xiao-Sheng; Zhang, Haixia

    2014-07-01

    We investigate the output performance of a cubic harvester which can scavenge low-frequency vibration energy from all directions. By adjusting the size and shape of the inside magnets, higher induced voltages and output power can be achieved. The optimal magnet is found to be cubic shape with the length of 6.35 mm (25.6% volume ratio), which can generate 4.27 mV root mean square voltage and 2.45 μW average power at the frequency of 28.86 Hz and acceleration of 1.17 g. The device is also demonstrated as a self-powered tilt sensor by measuring induced voltages at different tilt angles.

  13. Hydrophobic polymer covered by a grating electrode for converting the mechanical energy of water droplets into electrical energy

    Science.gov (United States)

    Helseth, L. E.; Guo, X. D.

    2016-04-01

    Water contact electric harvesting has a great potential as a new energy technology for powering small-scale electronics, but a better understanding of the dynamics governing the conversion from mechanical to electrical energy on the polymer surfaces is needed. Important questions are how current correlates with droplet kinetic energy and what happens to the charge dynamics when a large number of droplets are incident on the polymer simultaneously. Here we address these questions by studying the current that is generated in an external electrical circuit when water droplets impinge on hydrophobic fluorinated ethylene propylene film containing a grating electrode on the back side. Droplets moving down an inclined polymer plane exhibit a characteristic periodic current time trace, and it is found that the peak current scales with sine of the inclination angle. For single droplets in free fall impinging onto the polymer, it is found that the initial peak current scales with the height of the free fall. The transition from individual droplets to a nearly continuous stream was investigated using the spectral density of the current signal. In both regimes, the high frequency content of the spectral density scales as f -2. For low frequencies, the low frequency content at low volume rates was noisy but nearly constant, whereas for high volume rates an increase with frequency is observed. It is demonstrated that the output signal from the system exposed to water droplets from a garden hose can be rectified and harvested by a 33 μF capacitor, where the stored energy increases at a rate of about 20 μJ in 100 s.

  14. Electromechanical modeling of a honeycomb core integrated vibration energy converter with increased specific power for energy harvesting applications

    Science.gov (United States)

    Chandrasekharan, Nataraj

    Innovation in integrated circuit technology along with improved manufacturing processes has resulted in considerable reduction in power consumption of electromechanical devices. Majority of these devices are currently powered by batteries. However, the issues posed by batteries, including the need for frequent battery recharge/replacement has resulted in a compelling need for alternate energy to achieve self-sufficient device operation or to supplement battery power. Vibration based energy harvesting methods through piezoelectric transduction provides with a promising potential towards replacing or supplementing battery power source. However, current piezoelectric energy harvesters generate low specific power (power-to-weight ratio) when compared to batteries that the harvesters seek to replace or supplement. In this study, the potential of integrating lightweight cellular honeycomb structures with existing piezoelectric device configurations (bimorph) to achieve higher specific power is investigated. It is shown in this study that at low excitation frequency ranges, replacing the solid continuous substrate of a conventional piezoelectric bimorph with honeycomb structures of the same material results in a significant increase in power-to-weight ratio of the piezoelectric harvester. In order to maximize the electrical response of vibration based power harvesters, the natural frequency of these harvesters is designed to match the input driving frequency. The commonly used technique of adding a tip mass is employed to lower the natural frequency (to match driving frequency) of both, solid and honeycomb substrate bimorphs. At higher excitation frequency, the natural frequency of the traditional solid substrate bimorph can only be altered (to match driving frequency) through a change in global geometric design parameters, typically achieved by increasing the thickness of the harvester. As a result, the size of the harvester is increased and can be disadvantageous

  15. A Theory of Control for a Class of Electronic Power Processing Systems: Energy-Storage DC-To-DC Converters. Ph.D. Thesis

    Science.gov (United States)

    Burns, W. W., III

    1977-01-01

    An analytically derived approach to the control of energy-storage dc-to-dc converters, which enables improved system performance and an extensive understanding of the manner in which this improved performance is accomplished, is presented. The control approach is derived from a state-plane analysis of dc-to-dc converter power stages which enables a graphical visualization of the movement of the system state during both steady state and transient operation. This graphical representation of the behavior of dc-to-dc converter systems yields considerable qualitative insight into the cause and effect relationships which exist between various commonly used converter control functions and the system performance which results from them.

  16. Analysis, Design, Modeling, and Control of an Interleaved-Boost Full-Bridge Three-Port Converter for Hybrid Renewable Energy Systems

    DEFF Research Database (Denmark)

    Mira Albert, Maria del Carmen; Zhang, Zhe; Knott, Arnold

    2017-01-01

    This paper presents the design, modeling, and control of an isolated dc-dc three-port converter (TPC) based on an interleaved-boost full-bridge converter with pulsewidth modulation (PWM) and phase-shift control for hybrid renewable energy systems. In the proposed topology, the switches are driven......, a prototype is constructed and tested under the various modes, depending on the availability of the renewable energy source and the load consumption. The experimental results show that the two decoupled control variables achieve effective regulation of the power flow among the three ports....

  17. Wave Basin Experiments with Large Wave Energy Converter Arrays to Study Interactions between the Converters and Effects on Other Users in the Sea and the Coastal Area

    DEFF Research Database (Denmark)

    Stratigaki, Vasiliki; Troch, Peter; Stallard, Tim

    2014-01-01

    are measured to provide data for understanding WEC array interactions and to evaluate array interaction numerical models. Each WEC consists of a buoy with a diameter of 0.315 m and power take-off (PTO) is modeled by realizing friction based energy dissipation through damping of the WEC’s motion. Wave gauges...

  18. Computational simulations of the interaction of water waves with pitching flap-type ocean wave energy converters

    Science.gov (United States)

    Pathak, Ashish; Raessi, Mehdi

    2016-11-01

    Using an in-house computational framework, we have studied the interaction of water waves with pitching flap-type ocean wave energy converters (WECs). The computational framework solves the full 3D Navier-Stokes equations and captures important effects, including the fluid-solid interaction, the nonlinear and viscous effects. The results of the computational tool, is first compared against the experimental data on the response of a flap-type WEC in a wave tank, and excellent agreement is demonstrated. Further simulations at the model and prototype scales are presented to assess the validity of the Froude scaling. The simulations are used to address some important questions, such as the validity range of common WEC modeling approaches that rely heavily on the Froude scaling and the inviscid potential flow theory. Additionally, the simulations examine the role of the Keulegan-Carpenter (KC) number, which is often used as a measure of relative importance of viscous drag on bodies exposed to oscillating flows. The performance of the flap-type WECs is investigated at various KC numbers to establish the relationship between the viscous drag and KC number for such geometry. That is of significant importance because such relationship only exists for simple geometries, e.g., a cylinder. Support from the National Science Foundation is gratefully acknowledged.

  19. Implementing Nonlinear Buoyancy and Excitation Forces in the WEC-Sim Wave Energy Converter Modeling Tool: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Lawson, M.; Yu, Y. H.; Nelessen, A.; Ruehl, K.; Michelen, C.

    2014-05-01

    Wave energy converters (WECs) are commonly designed and analyzed using numerical models that combine multi-body dynamics with hydrodynamic models based on the Cummins Equation and linearized hydrodynamic coefficients. These modeling methods are attractive design tools because they are computationally inexpensive and do not require the use of high performance computing resources necessitated by high-fidelity methods, such as Navier Stokes computational fluid dynamics. Modeling hydrodynamics using linear coefficients assumes that the device undergoes small motions and that the wetted surface area of the devices is approximately constant. WEC devices, however, are typically designed to undergo large motions in order to maximize power extraction, calling into question the validity of assuming that linear hydrodynamic models accurately capture the relevant fluid-structure interactions. In this paper, we study how calculating buoyancy and Froude-Krylov forces from the instantaneous position of a WEC device (referred to as instantaneous buoyancy and Froude-Krylov forces from herein) changes WEC simulation results compared to simulations that use linear hydrodynamic coefficients. First, we describe the WEC-Sim tool used to perform simulations and how the ability to model instantaneous forces was incorporated into WEC-Sim. We then use a simplified one-body WEC device to validate the model and to demonstrate how accounting for these instantaneously calculated forces affects the accuracy of simulation results, such as device motions, hydrodynamic forces, and power generation.

  20. Parametric performance analysis of steam-injected gas turbine with a thermionic-energy-converter-lined combustor

    Science.gov (United States)

    Choo, Y. K.; Burns, R. K.

    1982-01-01

    The performance of steam-injected gas turbines having combustors lined with thermionic energy converters (STIG/TEC systems) was analyzed and compared with that of two baseline systems; a steam-injected gas turbine (without a TEC-lined combustor) and a conventional combined gas turbine/steam turbine cycle. Common gas turbine parameters were assumed for all of the systems. Two configurations of the STIG/TEC system were investigated. In both cases, steam produced in an exhaust-heat-recovery boiler cools the TEC collectors. It is then injected into the gas combustion stream and expanded through the gas turbine. The STIG/TEC system combines the advantage of gas turbine steam injection with the conversion of high-temperature combustion heat by TEC's. The addition of TEC's to the baseline steam-injected gas turbine improves both its efficiency and specific power. Depending on system configuration and design parameters, the STIG/TEC system can also achieve higher efficiency and specific power than the baseline combined cycle.

  1. Experimental Results of a DC Bus Voltage Level Control for a Load-Controlled Marine Current Energy Converter

    Directory of Open Access Journals (Sweden)

    Johan Forslund

    2015-05-01

    Full Text Available This paper investigates three load control methods for a  marine current energy converter using a vertical axis current  turbine (VACT mounted on a permanent magnet synchronous generator  (PMSG. The three cases are; a fixed AC load, a fixed pulse width  modulated (PWM DC load and DC bus voltage control of a DC  load. Experimental results show that the DC bus voltage control  reduces the variations of rotational speed by a factor of 3.5 at the cost  of slightly increased losses in the generator and transmission lines.  For all three cases, the tip speed ratio \\(\\lambda\\ can be kept close to  the expected \\(\\lambda_{opt}\\. The power coefficient is estimated to be  0.36 at \\(\\lambda_{opt}\\; however, for all three cases, the average  extracted power was about \\(\\sim 19\\\\%. A maximum power point  tracking (MPPT system, with or without water velocity measurement,  could increase the average extracted power.

  2. Power Flow Control of a Dual-Input Interleaved Buck/Boost Converter with Galvanic Isolation for Renewable Energy Systems

    DEFF Research Database (Denmark)

    Mira Albert, Maria del Carmen; Zhang, Zhe; Knott, Arnold

    2015-01-01

    DC microgrids or nanogrids have attracted increasing research interest in recent years. Therefore, as a critical component, dc-dc converters with multiple inputs are required. In this paper, a dual-input interleaved buck/boost converter is proposed and its corresponding power flow control methods...

  3. Low start-up voltage dc–dc converter with negative voltage control for thermoelectric energy harvesting

    Directory of Open Access Journals (Sweden)

    Pui-Sun Lei

    2015-01-01

    Full Text Available This Letter presents a low start-up voltage dc–dc converter for low-power thermoelectric systems which uses a native n-type MOS transistor as the start-up switch. The start-up voltage of the proposed converter is 300 mV and the converter does not need batteries to start up. The negative voltage control is proposed to reduce the leakage current caused by native n-type transistor and increase the efficiency. The proposed converter was designed using standard 0.18 µm CMOS process with chip size of 0.388 mm^2. The peak efficiency is 63% at load current of 1.5 mA. The proposed converter provides output voltage >1 V at maximum load current of 3.2 mA.

  4. Optimization of DC-DC Converters for Improved Electromagnetic Compatibility With High Energy Physics Front-End Electronics

    CERN Document Server

    Fuentes, C; Michelis, S; Blanchot, G; Allongue, B; Faccio, F; Orlandi, S; Kayal, M; Pontt, J

    2011-01-01

    The upgrade of the Large Hadron Collider (LHC) experiments at CERN sets new challenges for the powering of the detectors. One of the powering schemes under study is based on DC-DC buck converters mounted on the front-end modules. The hard environmental conditions impose strict restrictions to the converters in terms of low volume, radiation and magnetic field tolerance. Furthermore, the noise emission of the switching converters must not affect the performance of the powered systems. A study of the sources and paths of noise of a synchronous buck converter has been made for identifying the critical parameters to reduce their emissions. As proof of principle, a converter was designed following the PCB layout considerations proposed and then used for powering a silicon strip module prototype for the ATLAS upgrade, in order to evaluate their compatibility.

  5. Basin Testing of Wave Energy Converters in Trondheim: Investigation of Mooring Loads and Implications for Wider Research

    Directory of Open Access Journals (Sweden)

    Vladimir Krivtsov

    2014-04-01

    Full Text Available This paper describes the physical model testing of an array of wave energy devices undertaken in the NTNU (Norwegian University of Science and Technology Trondheim basin between 8 and 20 October 2008 funded under the EU Hydralabs III initiative, and provides an analysis of the extreme mooring loads. Tests were completed at 1/20 scale on a single oscillating water column device and on close-packed arrays of three and five devices following calibration of instrumentation and the wave and current test environment. One wave energy converter (WEC was fully instrumented with mooring line load cells, optical motion tracker and accelerometers and tested in regular waves, short- and long-crested irregular waves and current. The wave and current test regimes were measured by six wave probes and a current meter. Arrays of three and five similar WECs, with identical mooring systems, were tested under similar environmental loading with partial monitoring of mooring forces and motions. The majority of loads on the mooring lines appeared to be broadly consistent with both logistic and normal distribution; whilst the right tail appeared to conform to the extreme value distribution. Comparison of the loads at different configurations of WEC arrays suggests that the results are broadly consistent with the hypothesis that the mooring loads should differ. In particular; the results from the tests in short crested seas conditions give an indication that peak loads in a multi WEC array may be considerably higher than in 1-WEC configuration. The test campaign has contributed essential data to the development of Simulink™ and Orcaflex™ models of devices, which include mooring system interactions, and data have also been obtained for inter-tank comparisons, studies of scale effects and validation of mooring system numerical models. It is hoped that this paper will help to draw the attention of a wider scientific community to the dataset freely available from the

  6. Measurement techniques for the characterization in the frequency domain of regulated energy-storage DC-to-DC converters. M.S. Thesis

    Science.gov (United States)

    Bahler, D. D.

    1978-01-01

    Procedures are presented for obtaining valid frequency-domain transfer functions of regulated reactor energy-storage dc-to-dc converters. These procedures are for measuring loop gain, closed loop gain, output impedance, and audio susceptibility. The applications of these measurements are discussed.

  7. Investigating the Adaptability of the Multi-Pump Multi-Piston Power Take-Off System for a Novel Wave Energy Converter

    NARCIS (Netherlands)

    Wei, Y.; Barradas Berglind, J.J; van Rooij, M.; Prins, WA; Jayawardhana, B.; Vakis, A. I.

    2017-01-01

    In this work, a numerical model is developed in order to investigate the adaptability of the multi-pump multi-piston power take-off (MP2PTO) system of a novel wave energy converter (WEC). This model is realized in the MATLAB/SIMULINK environment, using the multi-body dynamics solver Multibody™, whic

  8. Simulación de Convertidores de Potencia en Sistemas Eólicos Simulation of Power Converters for Wind Energy Systems

    Directory of Open Access Journals (Sweden)

    Rui Melício

    2007-01-01

    Full Text Available En el presente trabajo se hace un análisis actual de la capacidad instalada de producción de energía eléctrica utilizando fuentes de energía renovable en Portugal y se analiza la situación actual relacionada con convertidores electrónicos de potencia. Además el trabajo aporta información sobre la simulación de topologías de convertidores de potencia en los sistemas de energía eólica, los convertidores usuales de dos niveles, el convertidor multinivel y el convertidor matricial. Se usa el método de la modulación de los pulsos de disparo mediante vectores espaciales de tensión y el control por modo de deslizamiento. Esta simulación permite concluir que las ondas de tensión y corriente en los convertidores de dos etapas AC/DC/AC se presentan con mejor comportamiento armónico que en el convertidor de una etapa AC/AC.This paper presents an analysis of the present installed electric power capacity of renewable energy power systems in Portugal, and analyzes the present state of power converters applied to wind farms. Also, this paper presents a simulation of a wind energy system with the usual topology for power converters, a two-levels converter, a multi-level converter and a matrix converter, using pulse modulation by space vector modulation. The simulation allows concluding that the waves for the electric voltage and the current in the converters AC/DC/AC have better performance than in the matrix converter AC/AC.

  9. Contribution of matrix converter in microgeneration for a sustainable energy planning; Contribuicao do conversor matricial na microgeracao para um planejamento energetico sustentavel

    Energy Technology Data Exchange (ETDEWEB)

    Romero, Javier Alexis Andrade; Romero, Jesus Franklin Andrade [Universidade Federal do ABC (UFABC), Santo Andre, SP (Brazil). Programa de Pos-Graduacao em Energia], emails: javier.romero@ufabc.edu.br, jesus.romero@ufabc.edu.br

    2010-07-01

    Once microturbine (MT) based generation systems present suitable and short term application conditions in distributed generation, a rigorous sustainability evaluation is necessary. In this work a Two Stage Matrix Converter (CM2E) that improves the energy efficiency performance is evaluated. In this sense, an analysis based on technological indicators regarding a sustainable energy planning is presented in technological, economic, social and environmental dimensions (author)

  10. Analysis of a Wave Energy Converter with Particular Focus on the Effects of Power Take-Off Forces on the Structural Responses

    DEFF Research Database (Denmark)

    Zurkinden, Andrew Stephen

    Wave energy is regarded as a major and promising renewable energy resource. The most critical factor to the success of deploying a wave energy converter in an ocean environment is the cost. The key factors affecting the costs include the performance, capital costs, operation and maintenance costs...... to evaluate the electrical power generated by a given wave energy device from a given wave condition. The first part of this work focuses on the development of such a numerical model. An important task is to quantify the wave-induced load effects to ensure that the input is correct and a safe and robust...

  11. Design of an Integrated Thermoelectric Generator Power Converter for Ultra-Low Power and Low Voltage Body Energy Harvesters aimed at EEG/ECG Active Electrodes

    Science.gov (United States)

    Ataei, Milad; Robert, Christian; Boegli, Alexis; Farine, Pierre-André

    2014-11-01

    This paper describes a design procedure for an efficient body thermal energy harvesting integrated power converter. This procedure is based on loss examination for a selfpowered medical device. All optimum system parameters are calculated respecting the transducer constraints and the application form factor. It is found that it is possible to optimize converter's working frequency with proper design of its pulse generator circuit. At selected frequency, it has been demonstrated that wide area voltage doubler can be eliminated at the expense of wider switches. With this method, more than 60% efficiency is achieved in simulation for just 20mV transducer output voltage and 30% of entire chip area is saved.

  12. Power Quality Control and Design of Power Converter for Variable-Speed Wind Energy Conversion System with Permanent-Magnet Synchronous Generator

    Directory of Open Access Journals (Sweden)

    Yüksel Oğuz

    2013-01-01

    Full Text Available The control strategy and design of an AC/DC/AC IGBT-PMW power converter for PMSG-based variable-speed wind energy conversion systems (VSWECS operation in grid/load-connected mode are presented. VSWECS consists of a PMSG connected to a AC-DC IGBT-based PWM rectifier and a DC/AC IGBT-based PWM inverter with LCL filter. In VSWECS, AC/DC/AC power converter is employed to convert the variable frequency variable speed generator output to the fixed frequency fixed voltage grid. The DC/AC power conversion has been managed out using adaptive neurofuzzy controlled inverter located at the output of controlled AC/DC IGBT-based PWM rectifier. In this study, the dynamic performance and power quality of the proposed power converter connected to the grid/load by output LCL filter is focused on. Dynamic modeling and control of the VSWECS with the proposed power converter is performed by using MATLAB/Simulink. Simulation results show that the output voltage, power, and frequency of VSWECS reach to desirable operation values in a very short time. In addition, when PMSG based VSWECS works continuously with the 4.5 kHz switching frequency, the THD rate of voltage in the load terminal is 0.00672%.

  13. Power quality control and design of power converter for variable-speed wind energy conversion system with permanent-magnet synchronous generator.

    Science.gov (United States)

    Oğuz, Yüksel; Güney, İrfan; Çalık, Hüseyin

    2013-01-01

    The control strategy and design of an AC/DC/AC IGBT-PMW power converter for PMSG-based variable-speed wind energy conversion systems (VSWECS) operation in grid/load-connected mode are presented. VSWECS consists of a PMSG connected to a AC-DC IGBT-based PWM rectifier and a DC/AC IGBT-based PWM inverter with LCL filter. In VSWECS, AC/DC/AC power converter is employed to convert the variable frequency variable speed generator output to the fixed frequency fixed voltage grid. The DC/AC power conversion has been managed out using adaptive neurofuzzy controlled inverter located at the output of controlled AC/DC IGBT-based PWM rectifier. In this study, the dynamic performance and power quality of the proposed power converter connected to the grid/load by output LCL filter is focused on. Dynamic modeling and control of the VSWECS with the proposed power converter is performed by using MATLAB/Simulink. Simulation results show that the output voltage, power, and frequency of VSWECS reach to desirable operation values in a very short time. In addition, when PMSG based VSWECS works continuously with the 4.5 kHz switching frequency, the THD rate of voltage in the load terminal is 0.00672%.

  14. Power Quality Control and Design of Power Converter for Variable-Speed Wind Energy Conversion System with Permanent-Magnet Synchronous Generator

    Science.gov (United States)

    Oğuz, Yüksel; Güney, İrfan; Çalık, Hüseyin

    2013-01-01

    The control strategy and design of an AC/DC/AC IGBT-PMW power converter for PMSG-based variable-speed wind energy conversion systems (VSWECS) operation in grid/load-connected mode are presented. VSWECS consists of a PMSG connected to a AC-DC IGBT-based PWM rectifier and a DC/AC IGBT-based PWM inverter with LCL filter. In VSWECS, AC/DC/AC power converter is employed to convert the variable frequency variable speed generator output to the fixed frequency fixed voltage grid. The DC/AC power conversion has been managed out using adaptive neurofuzzy controlled inverter located at the output of controlled AC/DC IGBT-based PWM rectifier. In this study, the dynamic performance and power quality of the proposed power converter connected to the grid/load by output LCL filter is focused on. Dynamic modeling and control of the VSWECS with the proposed power converter is performed by using MATLAB/Simulink. Simulation results show that the output voltage, power, and frequency of VSWECS reach to desirable operation values in a very short time. In addition, when PMSG based VSWECS works continuously with the 4.5 kHz switching frequency, the THD rate of voltage in the load terminal is 0.00672%. PMID:24453905

  15. Design of an integrated thermoelectric generator power converter for ultra-low power and low voltage body energy harvesters aimed at ExG active electrodes

    Science.gov (United States)

    Ataei, Milad; Robert, Christian; Boegli, Alexis; Farine, Pierre-André

    2015-10-01

    This paper describes a detailed design procedure for an efficient thermal body energy harvesting integrated power converter. The procedure is based on the examination of power loss and power transfer in a converter for a self-powered medical device. The efficiency limit for the system is derived and the converter is optimized for the worst case scenario. All optimum system parameters are calculated respecting the transducer constraints and the application form factor. Circuit blocks including pulse generators are implemented based on the system specifications and optimized converter working frequency. At this working condition, it has been demonstrated that the wide area capacitor of the voltage doubler, which provides high voltage switch gating, can be eliminated at the expense of wider switches. With this method, measurements show that 54% efficiency is achieved for just a 20 mV transducer output voltage and 30% of the chip area is saved. The entire electronic board can fit in one EEG or ECG electrode, and the electronic system can convert the electrode to an active electrode.

  16. The Effect of Converting to a U.S. Hydrogen Fuel Cell Vehicle Fleet on Emissions and Energy Use

    Science.gov (United States)

    Colella, W. G.; Jacobson, M. Z.; Golden, D. M.

    2004-12-01

    This study analyzes the potential change in emissions and energy use from replacing fossil-fuel based vehicles with hydrogen fuel cell vehicles. This study examines three different hydrogen production scenarios to determine their resultant emissions and energy usage: hydrogen produced via 1) steam reforming of methane, 2) coal gasification, or 3) wind electrolysis. The atmospheric model simulations require two primary sets of data: the actual emissions associated with hydrogen fuel production and use, and the corresponding reduction in emissions associated with reducing fossil fuel use. The net change in emissions is derived using 1) the U.S. EPA's National Emission Inventory (NEI) that incorporates several hundred categories of on-road vehicles and 2) a Process Chain Analysis (PCA) for the different hydrogen production scenarios. NEI: The quantity of hydrogen-related emission is ultimately a function of the projected hydrogen consumption in on-road vehicles. Data for hydrogen consumption from on-road vehicles was derived from the number of miles driven in each U.S. county based on 1999 NEI data, the average fleet mileage of all on-road vehicles, the average gasoline vehicle efficiency, and the efficiency of advanced 2004 fuel cell vehicles. PCA: PCA involves energy and mass balance calculations around the fuel extraction, production, transport, storage, and delivery processes. PCA was used to examine three different hydrogen production scenarios: In the first scenario, hydrogen is derived from natural gas, which is extracted from gas fields, stored, chemically processed, and transmitted through pipelines to distributed fuel processing units. The fuel processing units, situated in similar locations as gasoline refueling stations, convert natural gas to hydrogen via a combination of steam reforming and fuel oxidation. Purified hydrogen is compressed for use onboard fuel cell vehicles. In the second scenario, hydrogen is derived from coal, which is extracted from

  17. Pacific salmon (Oncorhynchus spp.) runs and consumer fitness: growth and energy storage in stream-dwelling salmonids increase with salmon spawner density

    Science.gov (United States)

    Rinella, Daniel J.; Wipfli, Mark S.; Stricker, Craig A.; Heintz, Ron A.; Rinella, Matthew J.

    2012-01-01

    We examined how marine-derived nutrients (MDN), in the form of spawning Pacific salmon, influenced the nutritional status and δ15N of stream-dwelling fishes. We sampled juvenile coho salmon (Oncorhynchus kisutch) and Dolly Varden (Salvelinus malma) during spring and fall from 11 south-central Alaskan streams that ranged widely in spawning salmon biomass (0.1–4.7 kg·m–2). Growth rate (as indexed by RNA–DNA ratios), energy density, and δ15N enrichment in spring-sampled fishes increased with spawner biomass, indicating the persistence of spawner effects more than 6 months after salmon spawning. Point estimates suggest that spawner effects on nutrition were substantially greater for coho salmon than Dolly Varden (268% and 175% greater for growth and energy, respectively), indicating that both species benefitted physiologically, but that juvenile coho salmon accrued more benefits than Dolly Varden. Although the data were less conclusive for fall- than spring-sampled fish, they do suggest spawner effects were also generally positive during fall, soon after salmon spawned. In a follow-up analysis where growth rate and energy density were modeled as a function of δ15N enrichment, results suggested that both increased with MDN assimilation, especially in juvenile coho salmon. Our results support the importance of salmon runs to the nutritional ecology of stream-dwelling fishes.

  18. X-Y Converter Family

    DEFF Research Database (Denmark)

    Bhaskar, Mahajan Sagar; Sanjeevikumar, Padmanaban; Wheeler, Patrick

    2016-01-01

    A New breed of a buck boost converter, named as the XY converter family is proposed in this article. In the XY family, 16 topologies are presented which are highly suitable for renewable energy applications which require a high ratio of DC-DC converter; such as a photovoltaic multilevel inverter...... system, high voltage automotive applications and industrial drives. Compared to the traditional boost converter and existing recent converters, the proposed XY converter family has the ability to provide a higher output voltage by using less number of power devices and reactive components. Other distinct...... features of the XY converter family are i) Single control switch ii) Provide negative output voltage iii) Non-isolated topologies iv) High conversion ratio without making the use of high duty cycle and v) modular structure. XY family is compared with the recent high step-up converters and the detailed...

  19. Study based on Wave EnergyConverter Technology Patent Analysis%基于波能发电装置技术专利分析的研究

    Institute of Scientific and Technical Information of China (English)

    曾涛; 何雨馨

    2015-01-01

    波能发电是当今新能源开发利用的重要方式之一,通过对波能发电装置国内外专利申请的情况进行分析统计,对国内外波能发电装置的技术发展路线和发展趋势进行梳理,分析我国波能发电与国外的技术差距,为我国波能发电装置的发展提供参考.%Electricity generated from wave energy is becoming an important wayof new energy exploitation, the pa-per tries to find out the technical route and developing trend of wave energy converter by analyzingthe data of therelevant patent application both in Chinaand abroad, analyzes the technology gapon wave energy electricity gen-eration with foreign countries, providing reference for the development of domestic wave energy converter.

  20. New Integrated Multilevel Converter for Switched Reluctance Motor Drives in Plug-in Hybrid Electric Vehicles with Flexible Energy Conversion

    DEFF Research Database (Denmark)

    Gan, Chun; Wu, Jianhua; Hu, Yihua;

    2017-01-01

    . In generator driving mode, the battery bank is employed to elevate the phase voltage for fast excitation and demagnetization. In battery driving mode, the converter is reconfigured as a four-level converter, and the capacitor is used as an additional charge capacitor to produce multilevel voltage outputs......, which enhances the torque capability. The operating modes of the proposed drive are explained and the phase current and voltage are analyzed in details. The battery charging is naturally achieved by the demagnetization current in motoring mode and by the regenerative current in braking mode. Moreover......, the battery can be charged by the external AC source or generator when the vehicle is in standstill condition. The SRM-based PHEV can operate at different speeds by coordinating power flow from the generator and battery. Simulation in MATLAB/Simulink and experiments on a three-phase 12/8 SRM confirm...

  1. Fully Integrated Ultra-Low Voltage Step-up Converter with Voltage Doubling LC-Tank for Energy Harvesting Applications

    Science.gov (United States)

    Jayaweera, H. M. P. C.; Pathirana, W. P. M. R.; Muhtaroğlu, Ali

    2015-12-01

    This paper reports the design, fabrication, and validation of a novel integrated interface circuit for ultra-low voltage step up converter in 0.18 μm CMOS technology. The circuit does not use off-chip components. Fully integrated centre-tap differential inductors are introduced in the proposed LC oscillator design to achieve 38% area reduction compared to the use of four separate inductors. The efficiency of the system is hence enhanced through the elimination of clock buffer circuits traditionally utilized to drive the step-up converter. The experimental results prove that the system can self-start, and step 0.25 V up to 1.7 V to supply a 46 μW load with 15.5% efficiency. The minimum validated input voltage is 0.15 V, which is boosted up to 1.2 V under open circuit conditions.

  2. Design and Implementation of a High Efficiency, Low Component Voltage Stress, Single-Switch High Step-Up Voltage Converter for Vehicular Green Energy Systems

    Directory of Open Access Journals (Sweden)

    Yu-En Wu

    2016-09-01

    Full Text Available In this study, a novel, non-isolated, cascade-type, single-switch, high step-up DC/DC converter was developed for green energy systems. An integrated coupled inductor and voltage lift circuit were applied to simplify the converter structure and satisfy the requirements of high efficiency and high voltage gain ratios. In addition, the proposed structure is controllable with a single switch, which effectively reduces the circuit cost and simplifies the control circuit. With the leakage inductor energy recovery function and active voltage clamp characteristics being present, the circuit yields optimizable conversion efficiency and low component voltage stress. After the operating principles of the proposed structure and characteristics of a steady-state circuit were analyzed, a converter prototype with 450 W, 40 V of input voltage, 400 V of output voltage, and 95% operating efficiency was fabricated. The Renesas MCU RX62T was employed to control the circuits. Experimental results were analyzed to validate the feasibility and effectiveness of the proposed system.

  3. 23 µW 8.9-effective number of bit 1.1 MS/s successive approximation register analog-to-digital converter with an energy-efficient digital-to-analog converter switching scheme

    Directory of Open Access Journals (Sweden)

    Lei Sun

    2014-08-01

    Full Text Available This study presents a successive approximation register analog-to-digital converter with an energy-efficient switching scheme. A split-most significant bit capacitor array is used with a least significant bit-down switching scheme. Compared with the conventional binary-weighted capacitor array, it reduces the area and average switching energy by 50 and 87% under the same unit capacitor. Moreover, capacitor matching requirement is relaxed by 75%. A prototype design was fabricated in a 0.13 µm complementary metal oxide semiconductor process. It consumes 23.2 µW under 1 V analog supply and 0.5 V digital supply. Measured results show a peak signal-to-distortion-and-noise ratio of 55.2 dB and an effective resolution bandwidth up to 1.1 MHz when it operates at 1.1 MS/s. Its figure-of-merit is 44.1 fJ/conversion-step.

  4. Wavelength Converters

    DEFF Research Database (Denmark)

    Kloch, Allan; Hansen, Peter Bukhave; Wolfson, David;

    1999-01-01

    at 2.5 Gbit/s, the regeneration causes a reduction of the required input power to an in-line EDFA of ~6 dB for a power penalty of 1 dB at a bit error rate of 10-9. If two converters are concatenated the power requirement is reduced ~8 dB. Obviously, the power reduction allows for longer spans between....... It is predicted that jitter accumulation can be minimised by using a 9-10 dB ratio between the signal and CW power also assuring a high extinction ratio. Using this guideline simulations show that 20 cross-gain modulation converters can be cascaded at 10 Gbit/s with only ~20 ps of accumulated jitter...... and an extinction ratio of ~10 dB.The regenerative capabilities of the cross-phase converters are described and verified experimentally at 20 Gbit/s, where the noise redistribution and improvement of the signal-to-noise ratio clearly is demonstrated by controlling the input power to an EDFA. In a similar experiment...

  5. An intense NIR emission from Ca14Al10Zn6O35:Mn(4+),Yb(3+)via energy transfer for solar spectral converters.

    Science.gov (United States)

    Lü, Wei; Jiao, Mengmeng; Shao, Baiqi; Zhao, Lingfei; Feng, Yang; You, Hongpeng

    2016-01-14

    To date, most current reports on the development and optimization of solar spectral converters have described the utilization of energy transfer among rare-earth ions. Here, we introduce non-rare-earth ion Mn(4+) to transfer energy to Yb(3+), which can exhibit strong near-infrared luminescence. It can harvest UV-blue photons and exhibits intense NIR emission of Yb(3+) around 1000 nm, perfectly matching the maximum spectral response of Si solar cells. It demonstrates for the first time that efficient energy transfer occurs with a decrease in the excited state lifetime and red photoluminescence (PL) from Mn(4+) with increasing Yb(3+) concentration. These results demonstrate that the Mn(4+) ions can be an efficient and direct sensitizer harvesting UV-blue photons. It could provide new avenues for developing harvesting Si-based solar cells.

  6. Characterization of U.S. Wave Energy Converter (WEC) Test Sites: A Catalogue of Met-Ocean Data, 2nd Edition

    Energy Technology Data Exchange (ETDEWEB)

    Dallman, Ann R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Water Power Technologies; Neary, Vincent S. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Water Power Technologies

    2015-09-01

    This report presents met-ocean data and wave energy characteristics at eight U.S. wave energy converter (WEC) test and potential deployment sites. Its purpose is to enable the comparison of wave resource characteristics among sites as well as the selection of test sites that are most suitable for a developer's device and that best meet their testing needs and objectives. It also provides essential inputs for the design of WEC test devices and planning WEC tests, including the planning of deployment, and operations and maintenance. For each site, this report catalogues wave statistics recommended in the International Electrotechnical Commission Technical Speci cation (IEC 62600-101 TS) on Wave Energy Characterization, as well as the frequency of occurrence of weather windows and extreme sea states, and statistics on wind and ocean currents. It also provides useful information on test site infrastructure and services.

  7. Design of a quasi-flat linear permanent magnet generator for pico-scale wave energy converter in south coast of Yogyakarta, Indonesia

    Science.gov (United States)

    Azhari, Budi; Prawinnetou, Wassy; Hutama, Dewangga Adhyaksa

    2017-03-01

    Indonesia has several potential ocean energies to utilize. One of them is tidal wave energy, which the potential is about 49 GW. To convert the tidal wave energy to electricity, linear permanent magnet generator (LPMG) is considered as the best appliance. In this paper, a pico-scale tidal wave power converter was designed using quasi-flat LPMG. The generator was meant to be applied in southern coast of Yogyakarta, Indonesia and was expected to generate 1 kW output. First, a quasi-flat LPMG was designed based on the expected output power and the wave characteristic at the placement site. The design was then simulated using finite element software of FEMM. Finally, the output values were calculated and the output characteristics were analyzed. The results showed that the designed power plant was able to produce output power of 725.78 Wp for each phase, with electrical efficiency of 64.5%. The output characteristics of the LPMG: output power would increase as the average wave height or wave period increases. Besides, the efficiency would increase if the external load resistance increases. Meanwhile the output power of the generator would be maximum at load resistance equals 11 Ω.

  8. Analysis, Design, Modelling and Control of an Interleaved-Boost Full-Bridge Three-Port Converter for Hybrid Renewable Energy Systems

    DEFF Research Database (Denmark)

    Mira Albert, Maria del Carmen; Zhang, Zhe; Knott, Arnold;

    2016-01-01

    This paper presents the design, modelling and control of a three-port (TPC) isolated dc-dc converter based on interleaved-boost-full-bridge with pulse-width-modulation and phase-shift control for hybrid renewable energy systems. In the proposed topology, the switches are driven by phase-shifted PWM...... of the proposed ac inductor based TPC is investigated by performing state-space modelling. Moreover, the derived mathematical models are validated by simulation and measurements. In order to verify the validity of the theoretical analysis, design and power decoupling control scheme, a prototype is constructed...

  9. Balancing Power Absorption and Structural Loading for a Novel Fixed-Bottom Wave Energy Converter with Nonideal Power Take-Off in Regular Waves: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Tom, Nathan M [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Yu, Yi-Hsiang [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Wright, Alan D [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2017-06-08

    In this work, the net power delivered to the grid from a nonideal power take-off (PTO) is introduced followed by a review of the pseudo-spectral control theory. A power-to-load ratio, used to evaluate the pseudo-spectral controller performance, is discussed, and the results obtained from optimizing a multiterm objective function are compared against results obtained from maximizing the net output power to the grid. Simulation results are then presented for four different oscillating wave energy converter geometries to highlight the potential of combing both geometry and PTO control to maximize power while minimizing loads.

  10. State of Charge Balancing Control of a Multi-Functional Battery Energy Storage System Based on a 11-Level Cascaded Multilevel PWM Converter

    DEFF Research Database (Denmark)

    Wang, Songcen; Teodorescu, Remus; Máthé, Lászlo

    2015-01-01

    This paper focuses on modeling and SOC (State of Charge) balancing control of lithium-ion battery energy storage system based on cascaded multilevel converter for both grid integration and electric vehicle propulsion applications. The equivalent electrical circuit model of lithium-ion battery...... is adopted to control active power and reactive power independently, and the zero-sequence voltage injection and a sorting and select algorithm are employed for SOC balancing control. The simulation results have been carried out with PLECS Simulation Software and are presented to validate the SOC control...

  11. Designing Dual-Active Bridge (DAB) converter for energy storage/recovery systems in a lighting smart grid context

    OpenAIRE

    Rico Secades, Manuel; García Llera, Daniel; López Corominas, Emilio Ramón; Calleja Rodríguez, Antonio Javier

    2014-01-01

    Lighting Systems are suffering and important evolution with the introduction of LED lighting systems with new strategies of energy savings, incorporation of renewable energy sources and optionally a bidirectional interconnection with the mains (AC grid or DC interconnection bus). Lighting Systems are moving to Lighting Smart Grids and step by step integrating in Smart City strategies. In this context design of modular and efficient energy storage/recovery systems are gaining importance lookin...

  12. Numerical Simulation of Wake Effects in the Lee of a Farm of Wave Dragon Wave Energy Converters

    DEFF Research Database (Denmark)

    Beels, C.; Troch, P.; De Visch, K.;

    2009-01-01

    . In this paper wake effects in the lee of a single Wave Dragon WEC and multiple Wave Dragon WECs are studied in a time-dependent mild-slope equation model. The Wave Dragon WEC is a floating offshore converter of the overtopping type. The water volume of overtopped waves is first captured in a basin above mean...... sea level and then drains back to the sea through hydro turbines. The wake dimensions behind a single Wave Dragon WEC are investigated for uni- and multidirectional waves. An increasing directional spreading results in a faster wave redistribution behind the WEC. The power absorption of a farm of five...... Wave Dragon WECs, installed in a staggered grid, is calculated for varying inbetween distances. It is observed that an in-between distance of 2D is preferred, when taking spatial and safety considerations into account....

  13. Application of the time-dependent mild-slope equations for the simulation of wake effects in the lee of a farm of Wave Dragon wave energy converters

    Energy Technology Data Exchange (ETDEWEB)

    Beels, Charlotte; Troch, Peter; De Visch, Kenneth; De Backer, Griet [Ghent University, Department of Civil Engineering, Technologiepark 904, B-9052 Zwijnaarde (Belgium); Kofoed, Jens Peter [Aalborg University, Department of Civil Engineering, Sohngaardsholmsvej 57, DK-9000 Aalborg (Denmark)

    2010-08-15

    Time-dependent mild-slope equations have been extensively used to compute wave transformations near coastal and offshore structures for more than 20 years. Recently the wave absorption characteristics of a Wave Energy Converter (abbreviated as WEC) of the overtopping type have been implemented in a time-dependent mild-slope equation model by using numerical sponge layers. In this paper the developed WEC implementation is applied to a single Wave Dragon WEC and multiple Wave Dragon WECs. The Wave Dragon WEC is a floating offshore converter of the overtopping type. Two wave reflectors focus the incident wave power towards a ramp. The focussed waves run up the ramp and overtop in a water reservoir above mean sea level. The obtained potential energy is converted into electricity when the stored water drains back to the sea through hydro turbines. The wave reflectors and the main body (ramp and reservoir) are simulated as porous structures, exhibiting the same reflection, respectively absorption characteristics as obtained for the prototype Wave Dragon WEC. The wake effects behind a single Wave Dragon WEC are studied in detail for uni- and multidirectional waves. The shadow zone indicating the wake effect is decreasing with increasing directional spreading. The wake in the lee of a farm of five Wave Dragon WECs, installed in a staggered grid (3 WECs in the first row and 2 WECs in the second row), is calculated for three in-between distances of respectively D, 2D and 3D, with D the distance between the tips of the wave reflectors of a single WEC. As a result, a farm of five Wave Dragon WECs installed in a staggered grid with an in-between distance of 2D is preferred, when taking cost and spatial considerations into account. (author)

  14. Impedance Source Power Electronic Converters

    DEFF Research Database (Denmark)

    Liu, Yushan; Abu-Rub, Haitham; Ge, Baoming

    Impedance Source Power Electronic Converters brings together state of the art knowledge and cutting edge techniques in various stages of research related to the ever more popular impedance source converters/inverters. Significant research efforts are underway to develop commercially viable...... and technically feasible, efficient and reliable power converters for renewable energy, electric transportation and for various industrial applications. This book provides a detailed understanding of the concepts, designs, controls, and application demonstrations of the impedance source converters/inverters. Key...... control methods. Presents the latest power conversion solutions that aim to advance the role of power electronics into industries and sustainable energy conversion systems. Compares impedance source converter/inverter applications in renewable energy power generation and electric vehicles as well...

  15. Comparative study between PI, RST and sliding mode controllers of a DFIG supplied by an AC-AC converter for wind energy conversion system

    Directory of Open Access Journals (Sweden)

    Ahmed Bourouina

    2015-12-01

    Full Text Available This paper deals with a variable speed device to produce electrical energy on a power network, based on a doubly-fed induction generator (DFIG supplied by a direct matrix converter used in wind energy conversion systems. In the first place, we carried out briefly a study of modelling on the whole system. In order to control the power flowing between the stator of the DFIG and the power network, a control law is synthesized using three types of controllers: PI, RST and sliding mode controllers. Their respective performances are compared in terms of power reference tracking, response to sudden speed variations, sensitivity to perturbations and robustness against machine parameters variations.

  16. Electrochemical treatment of tannery effluent using a battery integrated DC-DC converter and solar PV power supply--an approach towards environment and energy management.

    Science.gov (United States)

    Iyappan, K; Basha, C Ahmed; Saravanathamizhan, R; Vedaraman, N; Tahiyah Nou Shene, C A; Begum, S Nathira

    2014-01-01

    Electrochemical oxidation of tannery effluent was carried out in batch, batch recirculation and continuous reactor configurations under different conditions using a battery-integrated DC-DC converter and solar PV power supply. The effect of current density, electrolysis time and fluid flow rate on chemical oxygen demand (COD) removal and energy consumption has been evaluated. The results of batch reactor show that a COD reduction of 80.85% to 96.67% could be obtained. The results showed that after 7 h of operation at a current density of 2.5 A dm(-2) and flow rate of 100 L h(-1) in batch recirculation reactor, the removal of COD is 82.14% and the specific energy consumption was found to be 5.871 kWh (kg COD)(-1) for tannery effluent. In addition, the performance of single pass flow reactors (single and multiple reactors) system of various configurations are analyzed.

  17. On/off multi-poppet valve for switching manifold in discrete fluid power force system PTO in wave energy converters

    DEFF Research Database (Denmark)

    Hansen, Anders Hedegaard; Pedersen, Henrik C.; Andersen, Torben Ole

    2014-01-01

    Fluid power systems are the leading technology for power take off systems in ocean wave energy converters. However, fluid power systems often suffer from poor efficiency, especially in part loads. This degrades the PTO system efficiency and therefore lowers the energy production. To overcome...... less than 10 ms. The pilot stage is directly actuated and utilises internal valve pressure as supply and an external tank connection as drain. The current paper presents the multi-disciplinary design process leading to the final valve design. This includes the geometric design of the main stage......, the choice of pilot valve, structural mechanical issues and modelling and simulation of various valve configurations. Hence, a mechatronic design process is utilised to choose the best valve configuration....

  18. An Efficiency-Optimized Isolated Bidirectional DC-DC Converter with Extended Power Range for Energy Storage Systems in Microgrids

    Directory of Open Access Journals (Sweden)

    Xiaolong Shi

    2012-12-01

    Full Text Available This paper proposes a novel extended-single-phase shift (ESPS control strategy of isolated bidirectional full-bridge DC-DC converters (IBDCs which are a promising alternative as a power electronic interface in microgrids with an additional function of galvanic isolation. Based on the mathematical models of ESPS control under steady-state conditions, detailed theoretical and experimental analyses of IBDC under ESPS control are presented. Compared with conventional single-phase-shift (CSPS control, ESPS control can greatly improve the efficiency of IBDCs in microgrids through decreasing current stress and backflow power considerably over a wide input and output voltage range under light and medium loads. In addition, ESPS control only needs to adjust one single phase-shift angel to control transmission power, thus it retains implementation simplicity in comparison with dual-phase-shift (DPS control for microgrid applications. Furthermore, an efficiency-optimized modulation scheme based on ESPS and CSPS control is developed in the whole power range of IBDC for power distribution in microgrids. A 10 kW IBDC prototype is constructed and the experimental results validate the effectiveness of the proposed control strategy, showing that the proposed strategy can enhance the overall efficiency up to 30%.

  19. Impedance source power electronic converters

    CERN Document Server

    Liu, Yushan; Ge, Baoming; Blaabjerg, Frede; Ellabban, Omar; Loh, Poh Chiang

    2016-01-01

    Impedance Source Power Electronic Converters brings together state of the art knowledge and cutting edge techniques in various stages of research related to the ever more popular impedance source converters/inverters. Significant research efforts are underway to develop commercially viable and technically feasible, efficient and reliable power converters for renewable energy, electric transportation and for various industrial applications. This book provides a detailed understanding of the concepts, designs, controls, and application demonstrations of the impedance source converters/inverters. Key features: Comprehensive analysis of the impedance source converter/inverter topologies, including typical topologies and derived topologies. Fully explains the design and control techniques of impedance source converters/inverters, including hardware design and control parameter design for corresponding control methods. Presents the latest power conversion solutions that aim to advance the role of pow...

  20. CO2对脱磷转炉物料和能量的影响%Effect of CO2 on material and energy in dephosphorization converters

    Institute of Scientific and Technical Information of China (English)

    李智峥; 朱荣; 朱益强

    2016-01-01

    Based on the characteristics of CO2 at high temperature, material and energy models for CO2 using in a dephosphoriza-tion converter were established to verify the feasibility of CO2 for oxidation reactions. Based on practical working conditions in a facto-ry, the effects of CO2 on the converter temperature and gas were studied. It is discovered that the CO2 ratio can be controlled within 28%, the oxygen consumption can be reduced by 16%, and the CO ratio in the gas can be increased by about 12% when the scrap ratio is 8% and the utilization ratio of CO2 is 85%. Besides, as the utilization ratio of CO2 increases, the semi-steel temperature of the converter gradually decreases, and the oxygen consumption also lowers.%基于CO2在高温条件下的反应特性,建立了CO2用于脱磷炉冶炼的物料和能量分析模型,验证CO2用于脱磷炉冶炼过程参与氧化反应的可行性。在此基础上,基于某厂脱磷炉的实际冶炼工况,研究喷吹CO2对脱磷转炉温度、煤气等的影响。研究发现:当废钢比为8%和CO2利用率为85%时,CO2的喷吹比例可控制在28%以内,氧耗可降低16%,炉气中CO比例可提高约12%;同时随着CO2利用率的提高,脱磷炉的半钢温度逐渐降低,氧耗逐渐降低。