Vibration Analysis and System Simulation for a Stalled Wind Turbine

The aerodynamic characteristic of wind turbine is calculated by applying the Blade Element Momentum(BEM) theory.Also finite element mode analysis is done for the tower and the rotor.Then the multi-dynamic model of the wind turbine is built in Adams.Also the drive chain is calculated by applying state space method and programmed in Matlab/ Simulink.With that the combined simulation of vibration characteristics is carried out on the base of MATLAB/Simulink and ADAMS,in which the transmission effects and aero-elasticity coupling is fully considered.The results show that the method is able to simulate the vibration characteristic almost the same as software Bladed,which is well-known for analyzing performance and loads for the design and certification of wind turbines.     

An asymmetric fault ride-through control method forPMSG wind turbine based onsuper-capacitors

With the rapid increasing interaction between wind turbines and power systems, wind turbines have to have the fault ride-through (FRT) capability to ensure the safe operation of power grid. In order to improve the asymmetric FRT capability of permanent magnet synchronous generator (PMSG) wind turbine, a novel control FRT method based on super-capacitors is proposed. In this method, super-capacitors are connected to the DC bus of AC-DC-AC converter via a bi-directional DC-DC converter, and the power processed by the super-capacitors is controlled to limit the increasing of the DC bus voltage of the AC-DC-AC converter in grid failure condition, and to reduce the 2nd order voltage ripple in the DC bus. Meanwhile, the proposed control method employs the grid voltage feed-forward approach to reduce the negative sequence current component in the grid side converter. According to the low voltage ride through (LVRT) standard, the selection of the super-capacitor capacity is also discussed, and then a mathematical model of the super-capacitor with the bi-directional DC-DC converter is established for designing the controller. Simulation results for a 1MW PMSG wind turbine by MATLAB show that the proposed control method reduces both the negative sequence current component in grid side converter and the 2nd order voltage ripple in DC link at the same time. The results also demonstrate that the asymmetric FRT capability of PMSG wind turbine is improved, which verifies the effectiveness of the proposed control method in this paper.     

Overall control strategy and operational performances of a doubly fed wind turbine generator system

In order to comprehensively and correctly analyze the real-time operational characteristics of a grid-connected wind turbine generator system, it is necessary to analyze the overall control strategies and operation performances of the wind turbine generator system. According to the type of a doubly fed wind turbine generator system, the mathematical models of wind turbine, drive train and doubly fed induction generator (DFIG) are presented. From the viewpoints of the maximum wind energy capture and safe operation of the wind turbine, a maximum power output control strategy is proposed by considering the DFIG loss minimization, and a variable pitch control strategy is also presented by considering generator rotational speed restriction and the output power restriction. Combined with a power decoupling strategy of DFIG, the overall operational performances of the doubly fed wind turbine generator system are simulated. By comparing the simulation, theoretical analysis and actual operational data, the results show that the presented model and overall control strategies of the doubly fed wind turbine generator system are valid.     

Analysis on the Control of Variable Speed Wind Turbine Using Neural Network Controller

It is very difficult to build the accurate mathematical model of the wind turbine generator system because of the uncertainty of air kinetics and the complexity of power electronics, especially when the wind speed changes abruptly or there is a disturbance. But the classical control needs the model. Using neural network controller to the wind turbine generator system can overcome these difficulties. The wind speed can be followed and the maximum power can be obtained under low wind speed by using the power coefficient curve BP neural network and the optimum pitch angle BP neural network. The maximum power can be kept and under the allowed range in the condition of high wind speed. The simulation model and result are given under the environment of MATLAB. The fluctuation of wind speed can be controlled and the disturbance can be cancelled by BP neural network controller.     

Modeling and simulation of a grid connected wind turbine withdoubly fed induction generator

In order to fully research the effects of external excitations, such as wind speed, wind direction and voltage disturbance, on a grid connected wind turbine with doubly fed induction generator, a co-simulation model of MW-class wind turbine system is established by using Simpack and Matlab/Simulink software. Also, by considering the actual control strategies in the process of simulation, the relationship between external excitations and mechanical system is studied. According to time-domain simulation under the turbulent wind condition, the dynamic meshing forces of gears are analyzed. Besides, the vibration responses of tower are calculated under the different external excitations. Research results lay a foundation for dynamic performance optimization and reliability design of a wind turbine.     

Arrangement and design of main bearing for wind turbine

The wind turbine bearing runs under complicated loading and vibration condition and its design and analysis is a developing and crossing discipline. The typical main bearing arrangements for wind turbine are compared, including the 3-point arrangement with spherical roller bearing, double-row tapered roller bearing and cylindrical roller bearing, two single-row tapered roller bearings. The various factors including the wind turbine type, loading, cost and weight are considered in the design of wind turbine drive train. The influencing factor of bearing reliability and the relationship between wind load, drive train and bearing are studied. Based on an example of bearing reliability, the influence of complicated topography on wind load and bearing life is analyzed. The commonality of the wind farms with wind turbine failure is found, i.e. the topology and the wind condition of most wind turbine sites are very unfavorable, e.g. with sleep slope, not enough distance between adjacent wind turbines. Such factors can cause abnormal wind shear and turbulence, which can bring unexpected load onto the bearing. The key factors in the analysis procedure of topography and wind resource are discussed.     

Dynamic characteristics analysis of megawatt wind turbine drive train

Since the wind turbines are installed on the flexible support tower, the drive train of the wind turbines runs under severe work conditions with varying wind directions and loads. So its failure rate is high and it is the bottle neck of the wind power development. This work presents a study which takes the coupling effect of oscillating of tower barrel and the twisting vibration of driven train into account. Using the lumped parameter method, a coupled dynamic model for the megawatt wind turbine drive train is built by considering the flexible tower barrel support effects. Then, the dynamic characteristics of the megawatt wind turbine drive train are analyzed. The Campbell chart is used in this research to analyze the potential resonance points. And the potential resonance frequencies between the cutting in and cutting out rotational speed of the drive train are obtained. Finally, Simpack is used to analyze the dynamic characteristics of drive train and verify the correctness of the proposed method.     

Analysis of accelerated fatigue test technology for wind turbines gearbox

In order to satisfy the high reliability requirements of wind turbines gearbox, a method of accelerated fatigue test is proposed to verify the fatigue reliability of the gearbox. According to the design load spectrum, the equivalent load and the number of stress cycles of parts in gearbox are deduced. Based on Miner linear cumulative damage theory, the fatigue degree of the gears and bearings are calculated. A linear accelerated load spectrum with the equivalent fatigue ratio of design load spectrum is provided to check the reliability of the gearbox. The results show that this method can verify the reliability of wind turbine gearbox within about 800 h.     

搭载机电控制无级变速器混合动力汽车模式切换仿真分析

通过分析机电控制无级变速器(electrical-mechanical continuously variable transmission,EM-CVT)的结构特点,提出了搭载EM-CVT混合动力汽车的传动方案,建立了动力源数值模型、EM-CVT模型,分析了混合动力系统工作模式,并针对模式切换时的冲击问题,以减小冲击度为目标,通过分析典型工况下动力源输出转矩特性和各部件的动态特性,提出了基于发动机、ISG电机、自动离合器以及EM-CVT相互协调控制策略。利用MATLAB/SIMULINK仿真平台建立混合动力传动系统动力学模型,并对典型的模式切换过程进行了仿真分析。结果表明,所提出的控制策略能够有效控制混合动力传动系统在模式切换时产生的冲击,提高了混合动力汽车的驾驶舒适性。     

Open motion control architecture of wind turbineand main controller design

In this paper, we propose a method to solve the problems with stochastic nonlinear and point to point architecture of the wind turbines. The proposed method presents an open motion control architecture and a linearized torque control system based on power curve LUT. We reference the PLCopen motion control standard that is used to design the linearized torque and pitch systems of the wind turbines. This proposes a new methodology for the main controller design and the system integration of wind turbines.     

Dynamic optimization design of gear transmission system for wind turbine

The differential equation which governs the behavior of the gear transmission system of 1.5 MW wind turbine is established. The external excitation caused by wind speed fluctuation is discussed and the internal excitation due to time varying mesh stiffness and comprehensive error is also analyzed. The calculating formulations of the harmonic balance method of nonlinear dynamic equations are presented. Then, the multi objective dynamic optimization model is developed to minimize the value of vibration acceleration and the overall volume. The optimization of a practical example using mixed discrete combined programming is performed. The result shows that the proposed method of modeling and optimization design can effectively reduce the wind turbines gearbox vibration levels and weight.     

A new control design for grid integration ofDFIG wind farm with VSC-HVDC

This paper proposes a control scheme for a doubly-fed induction generator (DFIG) wind farm with VSC-HVDC grid integration to ensure secure and reliable operation of power system with fluctuated wind power penetration. The whole system dynamic models are respectively described. Based on vector control system with a virtual voltage orientation, a steady-state voltage control block and a dynamic voltage control block with a cross-product term of d-q currents are separately designed for WFVSC to control the corresponding parts of the wind farm voltage. Meanwhile, with the consideration of AC and DC side parameter variation and external disturbance, an improved backstepping control scheme with Lyapunov stability provement is also proposed for the GSVSC. The combination of the two schemes makes up the new control design of this study. Besides, to verify the performance of the proposed new control design, three different cases are suggested which contain the AC and DC side parameter variation and external disturbance such as local load cut off-in, grid voltage harmonics. Finally, numerical simulations using MATLAB/Simulink are presented for a 200MW DFIG wind farm with VSC-HVDC grid integration to validate the proposed control scheme and demonstrate the improved system operation performance. Moreover, the corresponding discussions are also presented for further illustrations.     

Wind Power Utilization Efficiency on Roof of Rectangular Buildings

Installing small wind turbines on the roof of buildings is a new way of wind power utilization in recently years. Based on the annual mean wind speed, the efficiency of wind power utilization on roofs of buildings was studied and the evaluation indexes for the utilization efficiency were proposed. With the help of CFD numerical analysis, the analysis on wind power utilization efficiency on flat roofs of rectangular buildings was carried out. The performance indexes of reference points under different windward angles were investigated. The best position and arrangement of wind turbines on the roof were also discussed. Furthermore, the utilization efficiency of four roofs with different shapes were analyzed and compared with that of flat roof.     

Independent pitch control strtegy anlysis of MW wind turbine

Under rel circumstnces, wind sher, tower shdow nd other fctors led to unblnced lods on wind wheel plne nd lrge tip displcement. While trditionl wind turbine control strtegy cnnot effectively solve the problem of uneven lod. In view of this, n individul pitch control strtegy is proposed by combining the liner qudrtic regultor with the disturbnce ccommodting control. Then this control strtegy is simulted under the environment of FAST nd Mtlb/Simulink softwre. Results show tht the proposed strtegy of individul pitch control cn reduce lods of min components nd improve opertionl life of wind turbines under wind sher cses.     

The design of torque dynamic sliding mode controller in permanent magnet synchronous generator for wind turbine

Permanent magnet synchronous generator for wind turbine is a multivariable nonlinear system with strong coupling. Considering the influence of the volatile parameters of the generator on the performance of vector control, the torque dynamic sliding-mode control strategy is further studied. The proposed first order dynamic sliding-mode control strategy reduces the chattering by using a new switch function constituted with derivative element. With the dynamic sliding-mode controller in the power outer loop, the PMSG vector control system shows excellent robustness and insensitivity to the parameters and disturbance, which is confirmed by simulation.     

Performance simulation of high-power wind turbine under the action of wind and wave

In order to research the offshore wind turbine which operates in harsh environment with transient and variable working conditions, the system is simulated and analyzed by simulation technology. The aerodynamic load of wind turbine is calculated by applying GDW theory and wave load is calculated by applying Airy wave theory. The drive chain is programmed in Matlab/ simulink and the flexible multi-body model of the wind turbine is built in Adams. The combined simulation of the wind turbine is carried out. The results of a 5 MW offshore wind turbine show that the method has excellent ability to simulate the performance almost the same as software Bladed result.     

Chaos expression of neuron dynamic simulation model with various stimulations

Chaos control based disease control has become a new direction for medical research. Chaos control can improve the study of nervous system diseases. To explain the inherent characteristics of such treatment with neurophysiology, a neuron dynamic simulation model, based on the Chay model, was built with MATLAB/SIMULINK. Various stimulations were inserted to analyze the dynamic change of the neuron action potential and its chaos expression. The experimental results show that different internal and external stimulations to the nervous system have great influence on membrane potential and chaos expression, indicating the importance and feasibility of chaos control in disease control.     

MATHEMATICAL MODEL AND DIGITAL SIMULATION FOR A REGENERATIVE HEATING SYSTEMS OF 200MW REHEATING STEAM TURBINE

Based on the physical processes of regenerative heating systems, the mathematical models of regenerative system,reheat system and steam turbine for a 200MW reheating steam turbine are presented, and the digital simulation of them on IBM-PC is also provided in this paper. The present work is a part of the study of the dynamic characteristics of all power systems. The mathematical model is expressed into state space form ,and its matrix is standardized to avoid the repeatation of establishing the models of heat exchangers.     

应用STATCOM的DFIG风力发电机低电压穿越能力分析

针对DFIG（double fed induction generator）风电机组低电压穿越能力（LVRT,low voltage ride through）问题,笔者基于STATCOM研究了一种电压外环与电流内环相结合的双闭环反馈控制策略,并仿真验证了所提出方法的有效性。将STATCOM分别安装风电机组机端、并网点高压侧和低压侧,且设置不同电压跌落深度,比较其补偿效果。实验结果表明,安装在风电机组机端时补偿效果最好。在电网电压跌落时,STATCOM能快速为电网输入无功,抬高风力机的机端电压,从而提高风电场的LVRT能力,从STATCOM输出无功大小和风电场机端电压被抬升的比例两方面分析,对于不同深度的电压跌落,STATCOM补偿效果都较为显著。     

Dynamic Simulation on the Hoisting Mechanism of a Crane

Considering the difficulties of mathematical analysis and the complex computer programming of numerical methods in solving dynamical problems of the multi-body dynamic system for the hoisting mechanism of a crane, in this paper, a multi-mass-multi-freedom model is set up and the simulation system of the model is built up applying MATLAB/SIMULINK toolbox. The differential equations of the model is solved with adaptive-step fourth-order Runge-Kutta method. In the study, the typical work conditions of the hoisting mechanism, such as start rise from ground, start rise/down in air, brake conditions, were simulated. The dynamic performance of the hoisting mechanism is studied and the results obtained are valuable to practice. This study improves the modeling accuracy of the hoisting mechanism and the results of precious theoretical analysis and numerical computation conclusions. The movement of every discrete body of the system can be modeled applying the methods suggested by this study and more consistent results between model and actual hoisting mechanism can be achieved.