MOD-2 Wind Turbine Research Articles

Three-phase AC-DC Converter for Direct-drive PMSG-based Wind Energy Conversion System

In this paper, a wind energy conversion system (WECS) is presented for the electrification of rural areas with wind energy availability. A three-phase AC-DC converter based on a bridgeless Cuk converter is used for power extraction from the permanent magnet synchronous generator (PMSG). The bridgeless topology enables the elimination of the front-end diode bridge rectifier (DBR). Moreover, the converter has fewer components, simple control, and high efficiency, making it suitable for a small-scale WECS. A squirrel cage induction motor (SCIM) is used to emulate a MOD-2 wind turbine to implement the PMSG-based WECS. A direct-drive eight-pole PMSG is used in this study; thus, a low-input-voltage system is designed. The converter is designed to operate in the discontinuous inductor current mode (DICM) for inherent power factor correction (PFC) and the maximum power point tracking (MPPT) is achieved through the tip-speed ratio (TSR) following. The performance of the developed system is analyzed through simulation, and a 500 W hardware prototype is developed and tested in different wind speed conditions.

Simplified Modelling of Oscillation Mode for Wind Power Systems

Wind turbine generators can be operated in various types of system configurations. Once the configurations change, the system oscillation mode shapes change accordingly. The modelling of the full system is necessary for studying this issue, yet it is quite hard. In this paper, a simple approach is developed to study the mode shapes of wind power systems without the necessity of adopting the complex full-system models. The key is that the q-d axis model of electric power system is transformed into the single-axis model, so that it could integrate with the equivalent circuit model of drive train mechanism. After analyzing some of the system configurations organized by the well-known MOD-2 wind turbine generator unit, the proposed approach is found to be effective for analyzing various oscillation modes such as the local torsional oscillations, as well as the inter-unit and inter-area oscillations.

H∞ Control for a Variable-Speed Stall-Regulated Wind Turbine Drive System

This paper presents an H∞ control application for a variable speed stall regulated wind turbine drive system. Mixed sensitivity problem is used to design a speed controller from a linear simplified model. The main purpose is to increase energy conversion efficiency and to reduce mechanical stress of the wind turbine. The control system performance is analyzed for MOD-2 wind turbine system.

Observations of wind turbine wakes and surface roughness effects on wind flow variability

Wind data collected at nine meteorological towers at the Goodnoe Hills MOD-2 wind turbine site were analyzed to characterize the wind flow over the site both in the absence and presence of wind turbine wakes. Free-flow characteristics examined were the variability of wind speed and turbulence intensity across the site as a function of wind direction and surface roughness. The nine towers' data revealed that scattered areas of trees upwind of the site caused pronounced variations in the wind flow over the site. At two towers that were frequently downwind of an extensive grove of trees, up to 30% reductions in wind speed and a factor of 2 to 3 increase in turbulence intensity were measured. A substantial increase in the magnitude of the wind gusts, as well as a considerable decrease in the mean wind speed, was observed when a tower was downwind of the trees.Wind turbine wake characteristics analyzed included the average velocity deficits, wake turbulence, wake width, wake trajectory, vertical profile of the wake, and the stratification of wake properties as a function of the ambient wind speed and turbulence intensity. The wind turbine rotor disk spanned a height of 15 m to 107 m. The nine towers' data permitted a detailed analysis of the wake behavior at a height of 32 m at various downwind distances from 2 to 10 rotor diameters (D). The relationship between velocity deficit and downwind distance was surprisingly linear, with average maximum deficits ranging from 34% at 2 D to 7% at 10 D. Largest deficits were at low wind speeds and low turbulence intensities. Average wake widths were 2.8 D at a downwind distance of 10 D. Implications for turbine spacing are that, for a wind farm with a 10-D row separation, array losses would be significantly greater for a 2-D than a 3-D spacing because of incremental effects caused by overlapping wakes. Other interesting wake properties observed were the wake turbulence (which was greatest along the flanks of the wake). the vertical variation of deficits (which were greater below hub height than above), and the trajectory of the wake (which was essentially straight).

Mod-2 wind-turbine field-operations experience

The Mod-2 wind turbine is now in a 2-year research/experimental operations phase which offers a unique opportunity to study the effects of single and multiple wind turbines interacting with each other, the power grid, and the environment. This paper addresses the field operations and research testing experienced at the Mod-2 Cluster Goodnoe Hills Research Test Site near Goldendale, Washington. Field operation, both routine and non-routine, are discussed as well as the role of the participating utility. Technical areas discussed pertain to system performance and loads. Specific research tests relating to acoustics, TV interference and wake effects conclude the paper.

Mod-2 Wind Turbine Loads Test Correlations

The Boeing Company, under contract to the Electric Power Research Institute (EPRI), has completed a test program on the Mod-2 wind turbines at Goodnoe Hills, Washington. The objectives were to update fatigue load spectra for different sites, to measure vortex generator effects, and to evaluate rotational sampling techniques. This paper presents the results of these tests and assesses the adequacy of prediction techniques.

Method for Evaluating Wind Turbine Wake Effects on Wind Farm Performance

A method of testing the performance of a cluster of wind turbine units and data analysis equations are presented which together form a simple and direct procedure for determining the reduction in energy output caused by the wake of an upwind turbine. This method appears to solve the problems presented by data scatter and wind variability. Test data from the three-unit Mod-2 wind turbine cluster at Goldendale, Washington, are analyzed to illustrate the application of the proposed method. In this sample case the reduction in energy was found to be about 10 percent when the Mod-2 units were separated a distance equal to 7 dia and winds were below rated.

Television Interference Due to Electromagnetic Scattering by the MOD-2 Wind Turbine Generators

Television Interference Due to Electromagnetic Scattering by the MOD-2 Wind Turbine Generators

Television Interference due to Electromagnetic Scattering by the MOD-2 Wind Turbine Generators

The characterization and identification of electromagnetic interference created by the slowly rotating blade of a MOD-2 wind turbine generator (WTG) is investigated. Field measurement data supports the thesis that at ground level the near field scattered component is an amplitude modulated secondary signal. A prediction methodology to define zones of interference to television broadcast reception is presented.

Whirl flutter analysis of a horizontal-axis wind turbine with a two-bladed teetering rotor

An investigation to explore the possibility of whirl flutter and to find the effect of pitch-flap coupling (δ 3) on teetering motion of the DOE/NASA Mod-2 wind turbine is presented. The equations of motion are derived for an idealized five-degree-of-freedom mathematical model of a horizontal-axis wind turbine with a two-bladed teetering rotor. The model accounts for the out-of-plane bending motion of each blade, the teetering motion of the rotor, and both the pitching and yawing motions of the rotor support. Results show that the Mod-2 design is free from whirl flutter. Selected results are presented indicating the effect of variations in rotor support damping, rotor support stiffnes, and δ 3 on pitching, yawing, teetering, and blade bending motions.

Filament Wound Large E-Glass/Epoxy Spars and Blades

A national wind energy program has been established to develop the technology required to make wind energy systems cost-competitive with conventional power generation systems and suitable for rapid commercial expansion to produce significant quantities of electrical power. The nominal 1500-kW Mod-2 Wind Turbine Generator being developed will require a rotor diameter of 300 ft (Fig. 1). Because of the considerable extension of technology that is required to produce the 150-ft blades, Structural Composites Industries and Kaman Aerospace Corporation have been awarded a contract by the Department of Energy through NASA-Lewis Research Center to design, fabricate, test, and evaluate a 150-ft composite blade. The primary structural element of the blade is a one-piece 20,000-lb spar fabricated using a new filament winding process, low-cost materials, and minimum labor.