De Tian

Computation of Hoisting Forces on Wind Turbine Blades Using Computation Fluid Dynamics

The hoisting forces on a 38.5m wind turbine blade in multiple positions are computed using the computational fluid dynamics (CFD) method. The computation model is constructed with the steady wind conditions, blade mesh model and the blade positions which are determined by the blade pitch angle, azimuth angle and rotor yaw angle. The maximal and minimal hoisting forces in three-dimensional coordinates are found and the corresponding pitch angle, azimuth angle and yaw angle are obtained. The change of the hoisting forces on wind turbine blades is analyzed. Suggestions are given to decrease the hoisting forces of the blade in open wind environment.

Rolling Bearing Fault Diagnosis Method Using Glowworm Swarm Optimization and Artificial Neural Network

Fault diagnosis has long been recognised as one of the most effective methods of reducing operation and maintenance cost in rotating industry, especially in bearings. A method based on BP neural network modified by glowworm swarm optimization (GSO) was proposed for fault diagnosis of rolling bearings. Six fault features were selected as the input of network. GSO algorithm was applied to simultaneously optimize the initial weight and threshold values of BP neural network. The reliability of the proposed technique was confirmed by experimental data, which indicated the potential applications of this method in the field of rolling bearing fault diagnosis.

Research on Maximum Wind Energy Capturing of DFIG

The doubly fed induction generator(DFIG) has been widely used in wind power generation system. It can alters speed of the rotor according to change of the wind speed, then contains the maximum tip speed ratio, in order to capture the maximum power from the wind energy. And the output frequency will not chang with the speed of generator. This paper studys the maximum wind energy capturing of DFIG. The theory analysis and simulation results based on MATLAB/Simulink demonstrate this control strategy is convenient and efficient.

Modeling and Simulation on Transformer Computer Protection in Wind Farm

This paper studies a single machine infinite bus system with two-winding transformer and access 110KV power system after improveing voltage. We established a system model of transformer based on MATLAB/Simulink, and established the computer protection data acquisition system model in wind farm, studied second harmonic ratio brake differential protection. Setted calculation combined with actual differential protection for a given parameter transformer, and use the simulink to simulate test of short-circuit. By the simulation study, we investigated the performance of transformer differential protection.

A Power System Stabilizer for Wind Power Generation

The parameter setting of the power system stabilizer (PSS) is very important. This paper presents a PSS for wind power generation. We describe a method of simulation for PSS based on MATLAB Simulink, and research that how to build the mathematic model and get the parameters that are fitted to the real power plant generator Excitation System and PSS used the Real Time Digital Simulator (RTDS), then builds the model on RTDS, and does the simulated testing. It is shown that this PSS can significantly influence the contribution that a wind farm can make to network damping. The optimal parameters of PSS can be obtained quickly through the approach of parameter optimization and it is a high efficiency and practicable parameter setting method. Performance capabilities superior to those provided by synchronous generation with automatic voltage regulator and PSS control are demonstrated.

Rotational Turbulent Wind Field Simulation of Wind Turbine

In order to accurately obtain the influence of rotational effect on fluctuating component of turbulent wind acted on wind turbine, rotational Fourier spectrum with considering rotational effect of rotor was deduced. Physical nature of the rotational Fourier spectrum embodied by coherence function and phase lag was indicated. Auto power spectral density and cross power spectral density of rotational Fourier spectrum with introducing phase lag were proposed. The spectrum matrix constructed by the module of rotational Fourier spectrum was decomposed with Choleskys method, according to the spectrum representation method with introducing phase lag, the random turbulent wind speed field was generated by superposing a set of cosine functions. Finally, an example involving simulation of the longitudinal turbulent wind velocity time series of a 1.5 MW three-bladed pitch regulated wind turbine was investigated. The target spectrum and simulated spectrum were compared. The result shows that the proposed algorithm is more accurate to simulate the fluctuating wind velocity of rotational blade.

Individual Pitch Control for Load Reduction Based on Norm Theory

As the capacity of wind turbine increases, unsteady blade loads and performance caused by asymmetrical effects like turbulence, wind shear and tower shadow lead to fatigue loads which seriously affect wind turbine life cycle. This paper focused on wind turbine fatigue load response characteristics, built the multiple input multiple output linearized matrix model, introduced individual pitch control algorithm for optimized disturbance control based on norm theory. Modeling, simulation and verification of the control algorithm are conducted in Matlab. The investigation is conducted based on a 2MW doubly-fed wind turbine. By comparing the results of wind turbine deflection rate and angle deflection rate to collective pitch control method, it shows the individual pitch control algorithm can significantly reduce wind turbine fatigue load, and the control effect is superior to traditional control algorithm.

Main Beam Optimization of Wind Turbine Blade Base on Multi-Objective Genetic Algorithm

Take s814 airfoil as an example, established the multi-objective optimization model of moment of inertia and the weight for wind turbine blade main beam,Using the genetic algorithm global optimization algorithm, and given the Pareto solution set of optimal with the form of Pareto front. Select four kinds of optimization results scheme to do finite element calculation. The results shows that the magnitude of moment of inertia accordance with the change trend of main beam deflection, the width and thick of beam cap have great affect on moment of inertia and weight, the nearer aerodynamic center of leading edge, the greater moment of inertia, the thick of web almost no influence on moment of inertia.

A Hybrid Method to Search the Optimal Hamiltonian Circuit

The objective of the well-known travelling salesman problem (TSP) is to search the optimal Hamiltonian circuit (OHC) in a tourist map. Finding the OHC becomes hard once the number of the cities and routes in the tourist map are large. The four vertices and three lines inequality was introduced as the constraints of the local optimal Hamiltonian paths (LOHPs) included in the OHC. The chaotic depth-priority algorithm was designed by adding the computation process with the chaotic operator to verify the rationality of the LOHPs generated with the depth-priority algorithm under the inequality constraints. A lot of non-LOHPs are abandoned in the search process and the search space of the OHC is reduced greatly. The method was verified with an example and it can be applied to the network optimization, path planning, task scheduling, assembly sequence planning etc.

Effect of Coherence Function on Rotational Fourier Spectrum of Wind Turbine

In order to consider the rotational effect of rotor and determine the exact loads of wind turbine generator system, rotational Fourier spectrum was deduced, and the physical nature of the rotational Fourier spectrum was indicated. Importance of coherence function to the rotational Fourier spectrum was analyzed according to physical nature, as well as the parameter sensitivity analysis of decay factor. The result shows that there is a sharp dip of rotational Fourier spectrum at the integer multiple rotational frequencies with Davenport exponential coherence function while its eliminated with coherence function supplied by IEC international standard. The rotational Fourier spectrum energy removes to the high frequency bands, the amplitudes of peak at the integer multiple rotational frequencies are increased with decay factor increased, which results in rotational effect more obvious.