Papers by Keyword: Wind Turbines

Abstract: Vortex generators (VGs) are commonly adopted to control the flow separation, and many researches have investigated their effects on the aerodynamic performance of wind turbines. However, nearly no attentions are paid to the VGs’ installation angle. Thus, in this paper, to investigate the effects of the VGs’ installation angle on airfoils, numerical simulations are conducted by CFD on the finite wing of NACA0012. According to the finite airfoil with or without VGs, three-dimensional models are established and numerical simulations are carried out in detail. It could be seen clearly that the VGs’ installation angle produces a significant impact on the aerodynamic performances. For some installation angles, special ranging from 45° to 90°, VGs can improve the lift-drag ratio apparently, even by 34.5%. While angle ranges from 15° to 30°, VGs negatively influence the lift-drag ratio. Furthermore, the fluctuation phenomenon is discussed through analysis of the streamlines and vortices. Based on those results, optimal aerodynamic performances could be achieved by the active control of the VGs’ installation angle.

Abstract: A high emergence of wind energy into the electricity market needs a parallel efficient advance of wind power forecasting models. Determining optimal specific speed and drive-train ratio is crucial to describe, comprehend and optimize the coupling design between a wind turbine-rotor and an electric generator (EG) to capture maximum output power from the wind. The selection of the specific design speed to drive a generator is limited. It varies from (1-4) for vertical axis wind turbines and (6-8) for horizontal axis wind turbines. Typically, the solution is an iterative procedure, for selecting the adequate multiplier ratio giving the output power curve. The latter must be relatively appreciated to inlet and nominal rated wind speeds. However, instead of this tedious and costly method, in the present paper we are developing a novel heuristic coupling approach, which is economical, easy to describe and applicable for all types of variable speed wind turbines (VSWTs). The principle method is based on the fact that the mechanical power needed of the wind turbine (WT) to drive the EG must be permanently closer to the maximum mechanical power generated by the (WT).

Abstract: This work addresses the problem of online fault detection of an advanced wind turbine benchmark under actuators (pitch and torque) and sensors (pitch angle measurement) faults of different type. The fault detection scheme starts by computing the baseline principal component analysis (PCA) model from the healthy wind turbine. Subsequently, when the structure is inspected or supervised, new measurements are obtained and projected into the baseline PCA model. When both sets of data are compared, a statistical hypothesis testing is used to make a decision on whether or not the wind turbine presents some fault. The effectiveness of the proposed fault-detection scheme is illustrated by numerical simulations on a well-known large wind turbine in the presence of wind turbulence and realistic fault scenarios.

Abstract: This paper presents an aeroelastic formulation based on the Finite Element Method (FEM) for performance and stability predictions of isolated horizontal axis wind turbines. Hamilton’s principle is applied to derive the equations of blade aeroelasticity, by coupling a nonlinear beam model with Beddoes-Leishman sectional unsteady aerodynamics. A devoted fifteen-degrees-of-freedom finite element to model kinematics and elastic behaviour of rotating blades is introduced. Spatial discretization of the aeroelastic equations is carried-out to derive a set of coupled nonlinear ordinary differential equations solved by a time-marching algorithm. The proposed formulation may be enhanced to face the analysis of advanced-shape blades, as well as the inclusion of the presence of the tower, and represents the first step of an ongoing activity on wind energy based on a FEM approach; as a consequence, results have to be considered as preliminary. Due to similarities between wind turbine and helicopter rotor blades aeroelasticity, validation results firstly concern with the aeroelastic response of helicopter rotors in hovering. Next, the performance of a wind turbine in terms of blade elastic response and delivered thrust and power is predicted and compared to that provided by a validated aeroelastic solver based on a modal approach as well as with experimental data.

Abstract: This paper summarizes the main elements of provisional calculations and charts which are sufficient to justify proposals for construction of a wind power station with the pre-designed capacity of 50 MW. Methodology of wind power potential assessment at the point of construction is given, a layout of the construction site and the structure of a wind farm are developed. The offered below materials make it possible to perform the first stages of the design.

Abstract: Wind energy is one of the promising renewable energy resources. The challenges in utilizing the renewable energy sources are making them reliable with good efficiency. Wind turbine plays a major role in industrial power supply during heavy wind conditions. However, in domestic applications, the small scale wind turbine has major issue of low starting torque due to low wind speed near the ground surface. These conditions make the air motion as laminar flow with the Reynolds number less than 5x10⁵. Hence, in some adverse condition there is a laminar flow separation which increases the drag and consequently reduces the lift force. This paper gives a comprehensive review on the investigations that are being carried out on low Reynolds number regime aerofoil and laminar separation bubble to enhance the lift force especially at low wind speed conditions.

Abstract: A description of a system, developed for the condition monitoring of wind turbines, which combines innovative, real time, and on-line oil sensor technologies is described. The system integrates the measurement of the three main parameters that assess the status of the lubricating oil in the lubrication system using different technologies: the degree of oil degradation using visible absorbance spectroscopy; the water content using near infrared spectroscopy; and the presence of wear debris using image processing technology. The measuring principles, sensor integration and validation test results obtained in artificially degraded oil samples are presented.

Abstract: Hydraulic pitch-controlled system is one of the components of wind turbines which are frequently prone to faults. Early fault prediction of the pitch control system can improve the operation reliability effectively and reduce the unnecessary loss. Wind turbines suffer much environmental interference; moreover, data-based fault prediction is vulnerable to occur false alarms by the impact of these factors. And it is difficult to implement the fault isolation. So this paper presents a fault prediction method for the pitch-controlled system, which is based on the mathematical model of wind turbines physical properties. The residual root mean square (RMS) is used as residual evaluation function. In the end of the paper, by the simulation using the hydraulic pitch actuator fault as the example, the effectiveness of the proposed fault prediction scheme is verified.

Abstract: With the increase capacity of wind turbines, grounding device's influence on the equipment and personal safety is becoming more and more significant. In order to calculate the grounding resistance of a wind turbine more accurately, in this paper, based on the Neumann integral formula and the average potential method is applied to derive a formula which can calculate the value of grounding resistance. A general MATLAB program corresponding to the calculation formula is compiled. By comparing the numerical value with the empirical analysis results and building a grounding resistance measurement test platform the correctness of the formulas and program is verified.