Showing papers on "Wave power published in 1987"

Optimal Strategies for Phase Control of Wave Energy Devices

Abstract: Phase control has previously been proposed for increasing energy output from wave power devices, and latching strategies have been tested for point absorbers and for pneumatic devices. Theoretical studies to determine optimal control strategies have not, however, been carried out until now. This paper provides a framework for the analysis of the problem, based essentially on L. S. Pontryagin's Maximum Principle. It indicates stable computational techniques for finding optimal solutions and summarize the results of studies on two devices - a point absorber and an oscillating water column.

Study of Backward Bent Duct Buoy

Abstract: Small wave power generators for navigation aids were used in practical in this 20 years, large wave power generator for island or land power supply is also developed in this 10 years. Backward Bent Duct Buoy (BBDB) is a new type buoy which has a Horizontal duct openning to backward. Single fuselage and twin fuselage BBDB were tested on a water tank, high electric generation, high energy conversion efficiency by wave,and low drag force by current were observed. Air pressure ratio values for both the backward facing and frontward facing are compared, and the reason of high output of BBDB (backward facing) is explained using water tank data. The floating wave power buoy can be dramatically improved by using the BBDB concept. This BBDB will be the most economical pneumatic wave energy conversion system for the island communities.

Utilization of Ocean Waves: Wave to Energy Conversion

Abstract: This collection of papers reviews both the state of the art in pneumatic wave energy conversion and the associated peripheral technologies, such as capture chamber research and design, turbine design and performance, and power take-off and integration. Other wave energy conversion methods are discussed. Several papers describe attempts at commercialization, while others report on various levels of research and development. Applications of the utilization of ocean waves in Japan, Norway, Denmark, and the United Kingdom are included. These papers were presented at the ASCE Specialty Conference, Utilization of Ocean Waves, held at the Scripps Institution of Oceanography, June 16 and 17, 1986.

Device for exploiting the wave energy of surface water and a wave power station which contains at least one such device

Abstract: The device described contains at least one swinging lever (4) provided with a floating body (5) and articulated so as to be able to swing in the vertical plane on a main body (3) anchored in the water and, if desired, floating. Between each swinging lever (4) and the main body (3) is a piston/cylinder arrangement (6) to supply a pressure medium preferably directly into a pressure accumulator. The compressed pressure medium is decompressed in a turbine or in a hydraulic engine and the drive shaft of said turbine or engine is connected to a generator to produce electricity. It is proposed that at least on each floating body (5) at least one additional flow energy converter (7) is provided by which also the inherent flow energy of the water located in the wave passage is constantly extracted. Preferably several such devices can be linked with an on-shore power station by means of power and control cables, and economically and reliably operating wave power stations can thus be set up.

The scattering of Alfven waves by density fluctuations

Abstract: The propagation of an Alfven wave packet through a medium containing time-dependent random density fluctuations is considered. The Alfven wave interaction with these density irregularities causes the transfer of wave power to both shear (Alfvenic) and compressive (magnetosonic) disturbances. The latter are dissipated and heat the plasma. The Alfven wave decay rate is computed in the limit of short-wavelength density fluctuations, the results are applied to the solar corona and interstellar medium.

Wave power plant or rocking ship for generating electricity

Abstract: The wave motion of the ship-like or board-like float (1) is converted into a rotary motion that drives a dynamo (12). The rocking ship utilises the sea's wave motion near the coast. The arc has a gear rack (9) on each side; these drive the two gear-wheels (13), which in turn drive the dynamo head (12). As soon as the waves start the float rocking, the arc tilts to windward and to lee. The gear-wheels and the dynamo head turn. The two drive gear-wheels are divided in the middle and have an engaging and disengaging device. They enable the dynamo head always to rotate in one direction about its axis. The electricity is transmitted via the anchor through a submarine cable (19) to the shore. The rocking ship is anchored parallel to the waves so that it can turn.

Research on perfect absorption of regular wave with the terminal device

Abstract: Theoretical and experimental studies have been carried out on wave power absorption using a so-called terminal device. The device consists of a buoy and the external measuring mechanism. It can give a visual display of the damping and restoring coefficients of the forces acting on the buoy by operating a gauge via a movable wave probe. Theoretical consideration of the mirror image buoy and external mechanism system shows that only the symmetrical wave component exists in a regular diffraction wave, therefore it is possible to cancel it by the radiation wave generated by heaving motion of the buoy. As a result, the wave energy absorption coefficient of the device in regular waves is almost 100%. Agreement between calculated and experimental results is fairly good.

Wave-power generating set

Abstract: PURPOSE:To stably obtain a desired output of power generation even if a wave- power generating set is installed in a shallow sea by providing a streamlining board on the opening of a flow path connecting the air chamber of said wave- power generating set floated on the surface, to below the water and generating large relative motion between a body and a water column in said flow path, which is short in length. CONSTITUTION:On the body of a wave-power generating set I like a power source for the light of a fairway marker buoy, a central pipe 1c which vertically passes through the body along its center axis is formed. In this central pipe 1c, an air chamber A is partitioned by a vertically moving water surface W2, and the turbine 5 of a generator 6 is provided on the opening 4a on the atmosphere side of the central pipe 1c. On the opening 1f on the submerged side of the central pipe 1c, a streamlining board 8 having a larger area than that of the opening 1f, is oppositely provided, preventing the movement of waves from directly affecting the opening 1f, to increase relative motion between the water surface W2 and the body 1.

Power generation device by utilizing wave power

Abstract: PURPOSE:To improve the power generation efficiency by suspending a guide rail onto the shafts parallel to the wave receiving plates of a buoy by bearing rings and installing an engaging chain of the buoy onto the pulley on the guide rail CONSTITUTION:Shafts 1 and 2 are installed in parallel to the wave receiving plates 4a and 4b, passing through the buoyancy center point T of a buoy, and a circular arcuate guide rail 3 is suspended so as to freely move in the bearing rings 1a and 2a at the both edges A pulley 5 is laied onto the guide rail 3 and freely rolled, and a hooking chain 7 is installed onto the pulley 5 Therefore, the wave receiving plate can be prevented from being influenced by the ocean current, and a right angle is always kept for the direction of wave, keeping the superior power generation efficiency

Sea-surface Variations and Energy: Tidal and Wave Power

Abstract: The movements of the sea surface are a result of the various external or ‘body’ forces acting upon the mass of the ocean (see this vol., Chappell, Ch. 2 and Peltier, Ch. 3). These movements (waves and tides) may be characterised by the periodicities associated with them which can vary from a few seconds to several days. Vertical surface-water movements and the associated subsurface particle motions represent a reservoir of stored energy. This energy has a lifetime equal to the lifetime of the solar system and is inexhaustible. Various estimates have been made as to the size of this energy resource, and Isaacs (1979) shows that the quantities of energy available from all sea-surface movements would amount to the earth’s total energy requirements in the year 2000. A number of schemes have been proposed for the harnessing of this vast power resource but many show little understanding of the engineering problems involved. It is proposed to discuss this resource here under two main headings based on the two major groups of cyclic sea-surface movements. First are the long period motions associated with Tides which have a dominant periodicity of around 12.5 hours and secondly the Wind Generated Waves having periods varying between four and twenty seconds. Within each section a brief introduction to the basic physics will be presented to give an understanding of the processes involved. There will not be any detailed mathematics as only the principles are important. Only a small number of formulae will be given and the reader is directed to appropriate texts for proof.

Wave Power Extraction at Coastal Structures by Means of Pendulor System : The First Experimental Operation of the Plant at Muroran-Port : Fluids Engineering, Heat Transfer, Combustion, Power, Thermophysical Properties,

Abstract: The authors reported on a 5kW wave power plant previously, which was deigned and installed by us. The plant consists of caisson which has two open water chambers faced to the offshore, and a wave pendulor in hung down in the pendulor drives an energy converter. Since April in 1983, the plant has been examined at Muroran-Port about 13 months. Through the experimental Operation, followings have been proved. 1. The plant is durable against to the rough sea. 2. Optimal efficiency of the wave power absorption is about 40∼50%. 3. The measured out put of oil motor is 16∼24 kW under 250% of rating wave power.

Ward-leonard device

Abstract: PURPOSE:To set the power factor of a supply current to one by performing such control that the phase difference of the input current of a Ward-Leonard device is determined based on a reactive power command, which should cancel a fundamental wave reactive current component of a reactive power generating load, and a fundamental wave power command of the Ward-Leonard device. CONSTITUTION:A lag reactive component of the fundamental wave current of the reactive power generating load is obtained by circuits 11 and 13, and the sign is inverted to obtain a command value qR*, and the fundamental wave current of the Ward-Leonard device is obtained by the other arithmetic circuits 12, 14, 15, and 18. A phase angle theta* is obtained in accordance with a fundamental wave current iL* of the Ward-Leonard device and the command value qR*. A point which is advanced from the peak value of the positive voltage in each phase by theta* is defined as the center of the turning-on period of a positive-side element of each phase. Thus, the power factor of the supply current of a power supply system to which another reactive power generating load is connected is set to one.

Device and method for generating reference voltages

Abstract: INVENTION, ON WAVE CREATES TENSION IN STANDS OR BEARING IN WHICH CHANGES BETWEEN POWER LEVELS ARE VIRTUALLY IDENTICAL. RESULT FOR THE WAVE, CHARGE ON FIRST CAPACITOR SAME VOLTAGE REFERENCE AVAILABLE, THEN TRANSFERRED ON THE CHARGE TO A SECOND CAPACITOR CF HIGHER CAPACITY. THIS CHARGE AND ARE REPEATED LOAD FOR SUBSEQUENT TRANSFER LEAD WAVE ON TERMINALS CAPACITOR CF. SH-SH CIRCUITS USED FOR SAMPLING THE LEVELS OF WAVE POWER TO ISSUE AND A SET OF REFERENCE DC VOLTAGES. THE DEVICE IS PARTICULARLY SUITABLE FOR PRODUCTION IN A MONOLITHIC INTEGRATED CIRCUIT AND CMOS IT CAN BE USED FOR CONVERTERS analog-FLASH.