Applied Mechanics and Materials Vols. 291-294

Abstract: Using computational fluid dynamics (CFD) software Fluent, numerical simulation for unsteady flow around the vertical axis wind turbine (VAWT) was performed, which was based on the UDF controlled sliding meshes method. And SST k-ω turbulent model and SIMPLE algorithm were used to solve the unsteady incompressible N-S equation. Velocity magnitude profile, pressure, the blade force and the torque had been obtained by doing this. The result shows this method can effectively simulate the unsteady flow field performance of the variable-pitch vertical axis wind turbine, and it provides a new method for variable-pitch vertical axis wind turbine’s simulations.

Abstract: The effects of structural damping on the aeroelastic stability have been investigated for composite thin-walled blade. Structural model of the composite thin-walled blade exhibits bending-bending-twist coupling, with accounting for the presence of pretwist angle. The aerodynamic model used in the present paper is the differential dynamic stall model developed at ONERA. The structural damping of the blade is predicted based on the analytical formulas of the modal damping of thin-walled composite structure. The effect of structural damping on aeroelastic stability is taken into account by using proportional damping matrix. By means of Galerkin method, the nonlinear aeroelastic equations are reduced to ordinary equations. The general aerodynamic forces are obtained from strip theory. The resulting equations are then linearized for small perturbation about the equilibrium point and the stability characteristics are investigated through eigenvalue analysis and time domain integration.

Abstract: In order to improve design reliability of wind turbine, it is needed that calculating method of aerodynamic load during wind turbine run. In paper from the angle of the project, NACA special airfoil of wind turbine is analyzed. Combined with thin-theory, airfoil angle of attack variation is deduced, meanwhile wind turbine actual force is calculated in each blade location point when blade of wind turbine is running based on wind shear theory and tower shadow effect. According to actual condition calculation method is engineering amplified, aerodynamic load calculation method of wind turbine blade is obtained. By this method aerodynamic load which is calculated match with experiment result, it fits better.

Abstract: Wind turbine pitch control need a higher demand due to the random changes in wind speed, this paper proposes using adaptive neural fuzzy inference system to control wind turbine pitch, and constructs a mathematical model of the wind turbine. Consider the error between the measured and the actual value of generator speed as the input to the controller. Take a simulation analysis to the adaptive neural fuzzy inference system controller under random wind speed. The simulation results show that the adaptive neural fuzzy inference system control strategy has good robustness and dynamic performance, to improve wind turbine pitch control is feasible and effective.

Abstract: To research the matching of main engine and turbocharger on sail-assisted ship, a 76000 deadweight tonnage cargo ship with 5S60MC main engine and TCA66 turbocharger was selected. The simulation model of working process of the engine was established, with AVL BOOST software, and verified by bench test results. Then, the model was used to analyze the matching of main engine and turbocharger, at constant speed mode of the main engine and constant speed mode of the ship. The results show that, the matching of main engine and turbocharger is acceptable, on the selected sail-assisted ship. However, special attentions should be paid to the turbocharger when the engine load is above 85.6% of the rated power at constant speed mode of the ship, to avoid surge of the compressor.

Abstract: Wind power prediction plays a pivotal role in reducing the wind power’s negative impact on grid and improving the market competiveness of wind energy. The prediction of wind speed is the key procedure of short-term wind power prediction. In this paper, a wind speed predicting approach based on CFD model was employed, and in order to improve the accuracy of the predicted wind speed, the two turbulence models of standard κ-ε model and RNG κ-ε model, which were applied in the computation of flow field, were studied and compared. The result shows that it has high accuracy on simulating the flow field and predicting wind speed by both the standard κ-ε model and RNG κ-ε model, and the precision is a little bit better when RNG κ-ε model is adopted. On the other hand, the convergence is better when standard κ-ε model is adopted.

Abstract: A gearbox condition assessment method for the Wind Turbine Generator (WTG) is proposed. Vibration signal’s Intrinsic Mode Functions (IMF) are decomposed by Empirical Mode Decomposition (EMD). Normalized Hilbert-Huang and Direct Quadrature (DQ) method are used to determine the instantaneous frequency. The HHS of vibration signals is plotted and then is shifted to match the pre-defined faulty gear condition by the Iterative Closest Point (ICP) algorithm to diagnose their similarities. The principle and effectiveness of the proposed method are illustrated by simulation, the fault types of gearbox can be identified by ICP algorithm effectively.

Abstract: Based on BLADED software, the aerodynamic performance of a large scale wind turbine blade was analyzed under variable condition. The results show that the rated power of the blade under variable condition is increased 10%, when the rated wind speed is changed from 10.5m/s to 11.0 m/s. The blade’s wind power coefficient is above 0.46, and its tip speed ratio is between 7.8 and 11.4. When its tip speed ratio is 9.5, the blade’s maximum wind power coefficient is 0.486. It is indicated that the blade has good aerodynamic performance and wide scope of wind speed adaptive capacity. The blade root’s equivalent fatigue load is 2.11 MN•m, and its extreme flapwise load is 4.61 MN•m. The loads under variable condition are both less than that of the designed condition, so the blade’s application under variable condition is safe.

Abstract: Now, the wind power in China develops quite rapidly and the installation of wind power is accounting more and more in power generating installation. Wind power, as a typical kind of renewable energy, is intermittent and unstable so that causes concerns about the damage it may do to power grid when integrate the large-scale wind power. According to that, integration is the main restraint for China to develop wind power. Energy storage, as an emerging technology, has been applied, tested and operated for a few years. It can solve integration problem efficiently and improve the efficiency of wind power integrating with the power grid. Hence, there is a large demand of energy storage on the wind power market. This paper chose grey forecast method to predict the installation of wind power in the near future. Then based on the forecast result, this paper selected low, medium and high rate of energy storage for the wind power system, and finally it predicted the demand of energy storage in the wind power integration from 2012~2015. This paper provided quantitative number and made it possible to plan further development.

Abstract: The conventional deterministic methods have been unable to accurately assess the active power output of the wind farm being the random and intermittent of wind power, and the probabilistic methods commonly used to solve this problem. In this paper the multi-state fault model is built considering run, outage and derating state of wind turbine, and then the reliability model of the wind farm is established considering the randomness of the wind speed, the wind farm wake effects and turbine failure. The active wind farm output probability assessment methods and processes based on the Monte Carlo method. The related programs are written in MATLAB, and the probability assessment for active power output of a wind farm in carried out, the effectiveness and adaptability of built reliability models and assessment methods are illustrated by analysis of the effects of reliability parameters and model parameters on assessment results.