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风力提水机可变行程之实现途径 总被引:1,自引:0,他引:1
描述了可变行程风力提水机与普通风力提水机相比的优点,探讨了可变行程的具体实现及控制方法,指出了可变行程风力提水存在的一些问题及今后的改进方向。 相似文献
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This paper presents selected results taken from an extensive investigation of the starting performance of a small horizontal-axis wind turbine. Starting was observed for blade pitch angles varying between 0 and 35° in 5° increments. At 0°, the angle for maximum power, the turbine’s 5 m diameter blades produce 5 kW at a wind speed of 10 m/s. At this pitch, starting is characterised by a long “idling period” in which the blade’s angular velocity increased only slowly because of the very high angles of attack. As the pitch angle increased, the idling period decreased. At all pitch angles, the measurements of angular velocity are compared with those obtained from a numerical integration of the equation for angular acceleration. The aerodynamic torque was obtained from a quasi-steady blade element analysis and the resistive torque of the drive train and generator was subtracted to determine the net torque accelerating the blades. The agreement between predicted and measured angular velocity was generally good and improved as the pitch angle increased. 相似文献
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A semi-empirical downscaling approach is presented to estimate spatial and temporal statistical properties of local daily mean wind speed under global climate change. The present semi-empirical downscaling method consists of two elements. Since general circulation models (GCMs) are able to reproduce the features of the present atmospheric general circulation quite correctly, the first element represents the large-scale circulation of the atmosphere. The second element is a link between local wind speed and large-scale circulation pattern (CP). The linkage is expressed by a stochastic model conditioned on CP types. Parameters of the linkage model are estimated using observed data series; then this model is utilized with GCM-generated CP type data corresponding to a 2 × CO2 scenario. Under the climate of Nebraska the lognormal distribution is the best two-parameter distribution to describe daily mean wind speed. The space-time variability of wind speed is described by a transformed multivariate autoregressive (AR) process, and the linkage between local wind and large-scale circulation is expressed as a conditional AR process, i.e. the autoregressive parameters depend on the actual daily CP type. The basic tendency of change under 2 × CO2 climate is a considerable increase of wind speed from the beginning of summer to the end of winter and a somewhat smaller wind decrease in spring. 相似文献
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This paper describes observations of the starting performance of a small horizontal-axis wind turbine in the context of a simple, quasi-steady analysis of the complex aerodynamics dominated by unsteadiness, high angles of attack, and low Reynolds number. Soon after they begin rotating, the blades can generate unexpectedly high torque. At the same time, the nondimensional pitch rate and reduced frequency are too small to suggest a significant increase of the torque through the effects of unsteadiness. The torque then decreases due to inappropriate blade angles of attack. This leads to a substantial “idle time” at both high and low wind speed, in which the rotating blades are accelerating only slowly and the angles of attack are slowly decreasing. When the angles are reduced to those giving high lift: drag ratios, the blades accelerate rapidly to complete the starting sequence by producing significant amounts of power. At low wind speeds, about 4 m/s, a gust is apparently required to complete the starting sequence. 相似文献
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与传统的风力提水机械不同,FS-3.5型风力发电提水机是由风力发电机、控制器、直流潜水电泵3大部件组成的提水系统。介绍了FS-3.5型风力发电提水机结构特点、工作特性及性能指标,对其进行了技术经济分析,探讨了该机组的应用前景。 相似文献
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This study was interested in the management of an energy production unit. A variable speed wind turbine (VSWT) was used as a principal source and a supercapacitor (SC) module was used as an energy storage system. Both were connected through a direct current bus. This unit was supplying a three-phase load using an inverter and an inductor and capacitor filter. In order to regulate the direct current bus voltage, the SC storage state was controlled by using a buck-boost converter according to load instructions and wind speed fluctuations. Then, a resonant controller was established to avoid any disturbances and to control the alternating line-to-line voltages of the load which may be unbalanced. This study has shown that the stability of the three-phase voltage source depends on the direct current bus power management and also on the line-to-line voltage control. Simulation results are presented to validate the efficiency of the control strategies used. 相似文献
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The inertia of wind turbines causes a reduction in their output power due to their inability to operate at the turbine maximum co‐efficient of performance point under dynamic wind conditions. In this paper, this dynamic power reduction is studied analytically and using simulations, assuming that a steady‐state optimal torque control strategy is used. The concepts of the natural and actual turbine time‐constant are introduced, and typical values for these parameters are examined. It is shown that for the typical turbine co‐efficient of performance curve used, the average turbine speed can be assumed to be determined by the average wind speed. With this assumption, analytical expressions for the power reduction with infinite and then finite turbine inertia are determined for sine‐wave wind speed variations. The results are then generalized for arbitrary wind speed profiles. A numerical wind turbine system simulation model is used to validate the analytical results for step and sine‐wave wind speed variations. Finally, it is used with real wind speed data to compare with the analytical predictions. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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M. Mohandes S. Rehman M. Abido S. Badran 《Energy Sources, Part A: Recovery, Utilization, and Environmental Effects》2016,38(1):140-148
Support vector machine is proposed to find wind speed at higher heights using measurements at lower heights. The mean absolute percentage error between measured and the estimated wind speed at height 40 m is found to be satisfactory. After validation at 40 m, the model was used to calculate the wind speed at hub heights up to 100 m. Annual energy yield was found to be increasing with hub height and, hence, accurate estimation of wind speed at heights becomes essential for realistic wind energy assessment. Furthermore, the plant capacity factor was found to be increasing approximately 1% for each 10-m increase in hub height. 相似文献