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111.
This paper investigates the use of disturbance models in the design of wind turbine individual pitch controllers. Previous work has used individual pitch control and disturbance models with the Multiblade Coordinate Transformation to design controllers that reduce the blade loads at the frequencies associated with the rotor speed. This paper takes a similar approach of using a disturbance model within the H∞ design framework to account for periodic loading effects. The controller is compared with a baseline design that does not include the periodic disturbance model. In constant wind speeds, the disturbance model design is significantly better than the baseline design at canceling blade loads at the rotor frequencies. However, these load reduction improvements become negligible even under low turbulent wind conditions. The two controllers perform similarly in turbulent wind conditions because disturbance augmentation improves load reduction only at the multiples of the rotor frequency in the yaw and tilt moment channels whereas turbulence creates strong collective bending moments. In addition, turbulent wind contains energy across a broad frequency spectrum and improvements at multiples of the rotor frequency are less important in these conditions. Therefore inclusion of periodic disturbance models in the control design may not lead to the expected load reduction in fielded wind turbines. 相似文献
112.
In this paper, a wind farm controller is developed that distributes power references among wind turbines while it reduces their structural loads. The proposed controller is based on a spatially discrete model of the farm, which delivers an approximation of wind speed in the vicinity of each wind turbine. The control algorithm determines the reference signals for each individual wind turbine controller in two scenarios based on low and high wind speed. In low wind speed, the reference signals for rotor speed are adjusted, taking the trade-off between power maximization and load minimization into account. In high wind speed, the power and pitch reference signals are determined while structural loads are minimized. To the best of authors’ knowledge, the proposed dynamical model is a suitable framework for control, since it provides a dynamic structure for behavior of the flow in wind farms. Moreover, the controller has been proven exceptionally useful in solving the problem of both power and load optimization on the basis of this model. 相似文献
113.
针对固定式海洋风机在随机风浪载荷及其联合作用下产生的具有倒立摆运动特征的纵摇,研究采用主动转动惯量驱动系统(Active Rotary Inertia Driver, ARID)对海洋风机纵摇进行控制的问题。ARID控制系统通过伺服电机驱动转动惯性质量产生控制结构摆动的最优力矩,从而减小海洋风机的纵摇运动。基于拉格朗日原理建立海洋风机-ARID控制系统的理论分析模型;采用Simulink对海洋风机-ARID控制系统的有效性进行验证,并分析系统参数(控制算法参数、转动惯量比等)对控制效果的影响规律;设计海洋风机-ARID控制系统的振动台试验,设置多种载荷激励形式,验证控制系统的稳定性与广谱有效性。数值模拟和试验结果均验证了所建立的分析模型的正确性,表明ARID控制系统对风机的纵摇运动具有显著的控制作用,为ARID控制系统在具有倒立摆运动规律的工程结构中的应用奠定理论基础。 相似文献
114.
针对实际工程条件,创新性地设计一种全新吸力筒形式,并借助SACS软件构建综合考虑土壤影响的吸力筒导管架风机模型。在极端工况下,详细分析该结构的性能。结果表明,在外部极端载荷作用下,导管架结构可满足工程要求,确保结构的整体稳定。采用Abaqus软件对过渡段和吸力筒部分强度进行精确校核,计算结果表明两者的强度均满足设计和使用需求,具备足够的承载潜力和稳定性。分析表明新设计的吸力筒在复杂工程背景下表现出色,为类似工程的设计与优化提供了可靠参考依据,同时也丰富海上风电吸力桶基础的研究与实践。 相似文献
115.
116.
CAD/CAM在水轮机叶片热模压成型工艺中的应用 总被引:3,自引:0,他引:3
介绍采用UG CAD/CAM及其强大的二次开发平台,解决混流式水轮机叶片热模压成型工艺中急需解决的叶片展开、压模设计及数控加工等关键技术问题。研究开发了叶片曲面的三维几何造型、密化计算处理、建立束展开的数学模型、及其带工程约束的几何近似展开方法及算法。并基于UG CAD/CAM用GRIP语言开发了解决这类技术问题相应的软件。该软件已实际用于叶片的制造,证明方法和软件都是可行的,具有良好的技术和经济性。 相似文献
117.
《Energy Policy》2015
This paper looks at the emerging risk/return profile for new renewable assets as a conventional wholesale electricity market progressively decarbonises. Using a detailed fundamental model of price formation risks, under increasing replacement of fossil fuel facilities with onshore and offshore wind, we show that the risk return profile becomes less attractive over time, and may therefore need sustained and possibly increasing policy support. Furthermore, we show that green certificate trading may become progressively more attractive as a supplementary support to wholesale prices, compared to fixed feed-in-tariffs. This is because the increasingly negative correlation between renewable output and wholesale prices reduces its revenue risk compared to fixed feed-in tariffs, if other factors remain constant, and thereby improves conventional financial performance risk metrics. In particular, this suggests that the recent energy policy change in Britain to move away from green certificates and into contracts-for-differences may have been ill-founded. 相似文献
118.
With the soaring energy demands, an urge to explore the alternate and renewable energy resources has become the focal point of various active research fronts. The scientific community is revisiting the inkling to tap the wind resources in more rigorous and novel ways. Recent idea of net-zero buildings has prompted the realization of novel ideas such as employment of omni-directional vertical-axis wind turbine (VAWT) for roof-top application etc. Generally, owing to the high computational cost and time, different levels of geometric simplifications are considered in numerical studies. It becomes very important to quantify the effect of these approximations for realistic and logical conclusions. The detailed performance of a 2.5 m diameter VAWT is sequentially presented with various levels of approximations spanning from two-dimensional to complete three-dimensional geometry. The performance along with the flow physics with focus on tip effects, spanwise flow effects, effect of supporting arms and central hub is discussed. We conclude that two-dimensional approximation can over predict the performance by 32%. Similar trend is also observed for other geometric and flow approximations. 相似文献
119.
In the variable speed wind turbine based on electromagnetic coupler (WT-EMC), a synchronous generator is directly coupled with grid. So like conventional power plants WT-EMC is able to support grid frequency inherently. But due to the reduced inertia of synchronous generator, its frequency support capability has to be enhanced. In this paper, the frequency support capability of WT-EMC is studied at three typical wind conditions and with two control strategies—droop control and inertial control to enhance its frequency support capability. The synchronous generator speed, more stable than the grid frequency which is the input signal for Type 3 and Type 4 wind turbine frequency support controller, is used for the calculation of WT-EMC supplementary torque command. The integrated simulation environment based on the aeroelastic code HAWC2 and software Matlab/Simulink is used to build a 2 MW WT-EMC model and study the frequency support capability of a wind farm consisting of WT-EMC. 相似文献
120.
Oscillating water column based wave energy extracting system has a low efficiency due to the poor performance of its principal power extracting component, the bidirectional turbine. In the present work, flow over a bidirectional impulse turbine was simulated using CFD technique and optimized using multiple surrogates approach. The surrogates being problem dependent may produce unreliable results, if a wrong surrogate is selected. Hence, multiple surrogates such as response surface approximation, radial basis function, Kriging and weighted average surrogates were incorporated in this problem. Same design points were used to generate multiple optima via multiple surrogates to enhance the robustness of the optimization process. Numbers of guide vanes and rotor blades were chosen as the design variables, and the objective was to maximize the blade efficiency. Reynolds-averaged Navier–Stokes equations were solved for analyzing the flow physics. The computed results were used to train the surrogates and find the optimal points via hybrid genetic algorithm. The surrogates were further applied to find the optimal flow parameters by changing flow velocity and turbine speed. The relative efficiency enhancement through our present approach was about 16%. Detailed methodologies, analysis of the results and surrogate applicability have been presented in this paper. 相似文献