Showing papers on "Tip-speed ratio published in 2006"
TL;DR: In this article, a 0.4 m diameter horizontal axis marine current turbine was tested in a circulating water channel and the power output was measured over a range of flow speeds, blade pitch and rotor yaw angles.
112 citations
Patent•
31 Oct 2006
TL;DR: In this paper, a closed loop system for controlling a volumetric displacement of a turbine driven electric power production system is presented. But the system is not suitable for the use of a large volume of fluid.
Abstract: A turbine (2) driven electric power production system (1), - said turbine (2) arranged for being driven by a fluid (3) having a fluid speed (v) varying in time, - said turbine (2) connected to a hydrostatic displacement pump (6) further connected to a hydrostatic displacement motor (8) as part of a closed loop hydrostatic transmission system (7), - said motor (8) arranged for driving an electrical generator (9) supplying AC power (10) at a frequency (fg) near a given desired frequency (fdes), characterized by a closed loop system arranged for controlling a volumetric displacement (13) of the hydrostatic motor (8), comprising - a fluid speed meter (11m) arranged for producing a speed signal (11s) representing a speed (v) of said fluid (3), and - a rotational speed meter (12m) arranged for providing a rotational speed signal (12s) representing a rotational speed measurement (ω) of said turbine (2), - a motor displacement control system (15) for continuously receiving said speed signal (11s) and said rotational speed signal (12s) and arranged for calculating a control signal (16), - a volumetric displacement control actuator (17) on said hydrostatic motor, arranged for receiving said control signal (16) for continuously adjusting a volumetric displacement (d) of said hydrostatic motor (8) for maintaining a set turbine tip speed ratio (tsrset) and thereby providing an improved power efficiency of the power production system (1) during fluctuations in said fluid speed (v).
96 citations
TL;DR: In this paper, the optimal TSR and the power factor of a wind turbine were predicted using artificial neural networks (ANN) based on the parameters involved for NACA 4415 and LS-1 profile types with 3 and 4 blades.
83 citations
01 Jan 2006
TL;DR: In this paper, a scaled model of a horizontal axis hydro turbine designed to harness energy from marine tidal currents is presented, and numerical and experimental investigations are conducted at the Department of Aeronautical Engineering of the University of Naples “Federico II.
Abstract: Marine current energy is one of the most interesting renewable and clean energy resources that have been less exploited respect to wind energy. Only in Europe this type of energy is available for 75 millions of KiloWatts and in terms of exploitable energy the amount is about 50 milliards of KiloWattHour. In the last years, the realization of horizontal axis turbine for the exploitation of the tidal currents is having, to world-wide level, a considerable increment. Many are the societies and the consortia that have decided to invest in such type of energetic source. The present paper provides a summary of the work done at the Department of Aeronautical Engineering (DPA) of the University of Naples “Federico II” regarding the numerical and experimental investigations of a scaled model of an horizontal axis hydro turbines designed to harness energy from marine tidal currents. The horizontal axis hydro turbine has been designed and analyzed using numerical codes available at DPA. Among these codes, some were already available at DPA and were based on standard Glauert’s blade element theory, modified following Prandtl’s theory and the “Higher Order Correction” method, while a new unsteady code, based on vortex lifting line theory, has been developed and now is under validation. The wind turbine has been designed to work at a specific Tip Speed Ratio (TSR) and particular effort has been put in order to avoid the cavitation on the blade surface. The blades are composed by airfoils with decreasing thickness from root to tip to accommodate both structural and aerodynamic needs. Airfoil design and selection are based on: E appropriate design Reynolds number; E airfoil thickness, according to the amount of centrifugal stiffening and desired blade rigidity; E roughness insensitivity, most important for stall regulated wind turbines; E low drag, not as important for small wind turbines because of passive over speed control and smaller relative influence of drag on performance; E high-lift root airfoil to minimize inboard solidity and enhanced starting torque.
42 citations
Patent•
11 Aug 2006
TL;DR: In this article, a small wind-powered electricity generation system, providing regulated AC electric power from wind energy to a power system grid, has a wind turbine that produces less than 10 kW of peak electric power in a permanent magnet generator that produces generator power with a frequency that varies with the wind speed.
Abstract: A small wind-powered electricity generation system, providing regulated AC electric power from wind energy to a power system grid, has a wind turbine that produces less than 10 kW of peak electric power in a permanent magnet generator that produces generator power with a frequency that varies with the wind speed. The wind turbine utilizes a cross-wind type rotor having a power coefficient that varies with the operating tip speed ratio and has an optimal tip speed ratio wherein the power coefficient is maximum. A power converter, for converting generator power to regulated electric power by applying a controlled load to the generator controls the operation of the wind turbine rotor such that the operating tip speed ratio is greater than the optimal tip speed ratio in a low wind speed region, is approximately equal to the optimal tip speed ratio in a medium wind speed region, and is greater than the optimal tip speed ratio in a high wind speed region.
34 citations
23 Oct 2006
TL;DR: F fuzzy controller was designed to control the rotation moment of wind wheel and the reverse moment of the generator and it can get smooth output and has better anti-interference property than the PID controller.
Abstract: To maintain the optimum blade tip speed ratio in order to obtain the maximum wind energy under lower wind speed, and to store or deliver some energy in order to enhance the flexibility of gear system and get stable output of power under higher wind speed, the angular speed of wind wheel is mainly used to control the variable speed wind turbine generator system. Building the accurate mathematical model of the wind turbine generator system is very difficult because of the uncertainty of air kinetics and the complexity of power electronics. To simplify and avoid the sophisticated mathematical model, fuzzy controller was designed to control the rotation moment of wind wheel and the reverse moment of the generator. The simulation model and results are obtained. Compared with the PID controller, using fuzzy controller the variable speed wind turbine generator system can get smooth output and has better anti-interference property.
33 citations
07 May 2006
TL;DR: A dynamic controller is discussed which uses the wind speed and rotor speed information to control the duty cycle of the buck-boost converter in order to operate the wind turbine at the optimum tip speed ratio.
Abstract: An isolated small wind turbine emulator is described in this paper. The system consists of a PC controlled variable speed dc motor coupled to a synchronous generator. Dump load is connected to the generator through a microcontroller controlled DC-DC converter. The varying aerodynamic torque of the wind turbine due to furling action and its resulting dynamics are incorporated in the emulator with the use of a PC based wind turbine model. A simple gain scheduled digital PI controller is designed which makes sure that the actual rotational speed of the DC motor is tracking the theoretical rotational speed of the wind turbine rotor. To extract the maximum power from the system, a dynamic controller is discussed which uses the wind speed and rotor speed information to control the duty cycle of the buck-boost converter in order to operate the wind turbine at the optimum tip speed ratio.
20 citations
TL;DR: In this article, a helicoidal vortex model is used to predict the flow past the blades of a wind turbine, and a 2D impulsively plunging plate problem is solved with a semi-implicit scheme and integral and numerical solutions compared and shown to be in excellent agreement.
20 citations
Patent•
20 Nov 2006
TL;DR: In this article, a wind power plant with a first set with at least one blade mounted on a shaft and at least another set of blades mounted on the same shaft and mounted such that the blade sets will have the same direction of revolution and the same number of revolutions was considered.
Abstract: The present invention relates to a wind power plant with a first set with at least one blade mounted on a shaft and at least one second set with at least one blade mounted on the same shaft and mounted such that the blade sets will have the same direction of revolution and the same number of revolutions. The second set of blades has a length which is smaller than that of the first set of blades and has another optimal tip speed ratio than the first set of blades, whereby the two sets of blades are optimised with regard to power output at the same number of revolutions. The ratio between the lengths of the two sets of blades can be determined approximately by the ratio between the optimal tip speed ratios of the two sets of blades. Alternatively the second set of blades can be constructed to have an optimal tip speed ratio, which is determined on the basis of the ratio between the length of the two sets of blades and the optimal tip speed ratio for the one set of blades. The two or more sets of blades can be placed either right behind each other or in the same rotor plane and, according to the invention, the two sets of blades can be constituted by a small wind rose and a larger fast-runner. The invention further relates to use of such wind power plant.
19 citations
Journal Article•
TL;DR: In this paper, a method of improving the self-starting of an H-type Darrieus vertical axis wind turbine by incorporating a helical Savonius turbine was described.
Abstract: The inherent problem of a Darrieus wind turbine is its inability to self-start. Usually, a motor is used to provide angular acceleration until lift forces are produced in the airfoil blades or up until the turbine can already sustain its speed on its own. This paper describes a method of improving the self-starting of an H-type Darrieus vertical axis wind turbine (VAWT) by incorporating a helical Savonius turbine thus utilizing a drag-lift combination. The effect of each turbine in the combination relative to each other is investigated by testing a prototype windmill consisting of three NACA 0015 airfoil blades combined with a Savonius rotor with a helix angle of 180 degrees and whose swept area equals 30% of the entire turbine.
3 citations
16 Oct 2006
TL;DR: A nonlinear control strategy of Elman network with input and output context layers is proposed in the paper, which can effectively overcomes disadvantages of tradition control that accuracy of pitch angle is limited by specified model and work time.
Abstract: Power control is required for large grid integration variable speed wind turbine at above rated wind speed. A nonlinear control strategy of Elman network with input and output context layers is proposed in the paper, which can effectively overcomes disadvantages of tradition control that accuracy of pitch angle is limited by specified model and work time. Novel modified Elman network structure merges self-feedback information of input and output nodes to approximate power coefficient inverse model and acts as controller. It can precisely supply an optimal pitch angle set point according to limited power coefficient and tip speed ratio during large wind variation region and maintain power output at rated power. Process equations of wind turbine, network structure and controller algorithm are described in the paper. Simulation results show that proposed control strategy is effective
Patent•
31 Oct 2006
TL;DR: In this article, a closed loop system for controlling a volumetric displacement control actuator on a hydrostatic motor was proposed for a turbine-driven electric power production system, where the motor displacement control system was characterized by a closed-loop system consisting of a fluid speed meter (11m) and a rotational speed meters (12m) for producing a speed signal representing a speed (v) of the fluid.
Abstract: The present invention relates to a turbine driven electric power production system (1), wherein the turbine (2) is arranged for being driven by a fluid (3) having a fluid speed (v) varying in time, and is connected to a hydrostatic displacement pump (6) further connected to a hydrostatic displacement motor (8) as part of a closed loop hydrostatic transmission system (7); and the motor (8) is arranged for driving an electrical generator (9) supplying AC power (10) at a frequency (fg) near a given desired frequency (fdes). The turbine driven electric power production system (1) is characterized by a closed loop system arranged for controlling a volumetric displacement (13) of the hydrostatic motor (8), comprising - a fluid speed meter (11m) arranged for producing a speed signal (11s) representing a speed (v) of said fluid (3), and - a rotational speed meter (12m) arranged for providing a rotational speed signal (12s) representing a rotational speed measurement (); of said turbine (2), - a motor displacement control system (15) for continuously receiving said speed signal (11s) and said rotational speed signal (12s) and arranged for calculating a control signal (16), - a volumetric displacement control actuator (17) on said hydrostatic motor, arranged for receiving the control signal (16) for continuously adjusting a volumetric displacement (d) of said hydrostatic motor (8) for maintaining a set turbine tip speed ratio (tsr set) and thereby providing an improved power efficiency of the power production system (1) during fluctuations in said fluid speed (v).
Dissertation•
01 Aug 2006
TL;DR: In this paper, the conceptual design of the wind turbine prototype was developed by considering the aspects of application requirements, configuration, functions and performance, the rotor blades were the most critical parts and they were analyzed using aerodynamic theory.
Abstract: Malaysia is situated in the equatorial zone and experiences low and unsteady wind speed. As a result, most of the existing wind turbines are not suitable for Malaysian application. High capital cost, low regional wind speed, incorrect matching between existing wind turbines and available wind speed as well as the level of technology are barriers to the use of wind energy conversion system. This project is a study on low cost, medium rotational speed, small scale stand-alone wind turbine for electrical power generation in low wind speed region. It involves designing, fabricating, testing and determining (blade and rotor configuration) a suitable wind turbine. A study on wind resources in Malaysia and the feasibility of its application showed that there is a possibility to utilise wind energy especially in the coastal areas and islands. The conceptual design of the wind turbine prototype was developed by considering the aspects of application requirements, configuration, functions and performance. The rotor blades were the most critical parts and they were analysed using aerodynamic theory. Wind turbine rotor models were fabricated and tested in a wind tunnel. The components and mechanisms were designed, built and analysed through computer-aided-design (CAD) modeling, theoretical calculation and computer software simulation. Various loads on the wind turbine structures were also examined. An indoor test rig was built for the testing of the wind turbine prototype, in order to obtain the power and torque coefficient at various tip speed ratio (CPmax = 36.8%). The prototype was also field tested to verify its start-up speed and feasibility of power generation. It has demonstrated good strength, component integrity and yaw response in the field test. The findings suggested that the optimum performance of this innovative wind turbine (TSR = 2.7 - 4.0) falls in the operating range that matched with the available wind speed (V8 = 2.2 - 7.0 m/s) if the load matching is properly done. The work developed is sufficient for further investigation into the refinement of every sub-assembly of the system.
01 Jun 2006
TL;DR: In this article, a method of improving the self-starting of an H-type Darrieus vertcial axis wind turbine by incorporating a helical Savonius turbine was described.
Abstract: The inherent problem of a Darrieus wind turbine is its inability to self-start. Usually, a motor is used to provide angular acceleration until lift forces are produced in the airfoil blades or up until the turbine can already sustain its speed on its own. This paper describes a method of improving the self-starting of an H-type Darrieus vertcial axis wind turbine (VAWT) by incorporating a helical Savonius turbine thus utilizing a drag-lift combination. The effect of each turbine in the combination relative to each other is investigated by testing a prototype windmill consisting of three (3) NACA 0015 airfoil combined with a Savonius rotor with a helix angle of 180 degrees and whose swept area equals 30% of the entire turbine.