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World Non-Grid-Connected Wind Power and Energy Conference (WNWEC), 2010

Date 5-7 Nov. 2010

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  • [Front matter]

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  • Prospects and status of non-grid-connected wind power all over the world

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    People living in 35% of the landmass of the world have no electrical grid and they live mostly in darkness. These are the most appropriate cases for non-grid-connected wind power. Non-grid-connected wind power systems will combine with large-capacity energy storage system or high energy-loaded industries. There is a direct need to develop high capacity electrical energy storage system at cheap cost. Non-grid-connected wind power systems will be wide-spread and can meet the demand of the deprived world. View full abstract»

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  • Balancing fluctuating power sources

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    It is necessary to combine and integrate technologies since no single renewable energy source is sufficient to be able to stand alone. Non-grid applications will be applied as well. Because of fluctuation of wind and solar power, integration of new energy including non-grid solutions were important to offer a steady consumption of power. Proper storage and comprehensive utilization of power were needed to make full use of power. Several types of storage of power was introduced and a certain example for Combined Heat and Power (CHP) was given in this paper. In Demark, combined heating/cooling and power system was used to make improvement of energy efficiency, in which hot water was used as medium. By district heating and CHP, the rate of energy effeciency was increased about 50%, compared with conventional power plants. Fossil fuel was replaced with biomass storage to solve the enviornmental problems. Average use of CHP was just 9%, so CHP could be developed greatly in the future. View full abstract»

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  • A study on financing strategy of China's wind power industry

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    Since the resources and environmental problems have become increasingly prominent in China, the wind power industry, as one of the new energy sources, is now developing at high speed to adapt to the needs of transforming national economic growth mode. At present, the fund demand of the wind power industry appears particularly urgent in China. This paper analyzed the current development status of China's wind power industry, finding that the wind power industry has significant development potential and positive future prospects in China, and the realization of which requires huge financial support. For this purpose, we proposed diversified financing strategies for wind power enterprises in order to achieve the sustainable development of China's wind power industry. View full abstract»

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  • Study on integration of production, education and research for non-grid-connected wind power

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    Wind power industry is an explosively growing industry, and wind power utilization is a sunrise industry in the new century. The application of large-scale non-grid-connected wind power throws the convention to the grid, so that the field, which could use non-grid-connected wind power, is extended. In this paper, the method of integration of production, education and research for non-grid-connected wind power is studied. The approach of integration of production, education and research is discussed from the viewpoint of promoting cohesion for technological achievements. The reasons for choosing this topic, the method of developing integration and the mode of promoting integration are investigated. View full abstract»

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  • Effects of STATCOM on wind turbines equipped with DFIGs during grid faults

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    Nowadays, the power system is facing new challenges in increasing renewable energy sources' penetration. One of these problems is voltage stability in wind farms equipped with doubly fed induction generators (DFIGs) during grid faults. Flexible AC Transmission System (FACTS) devices can be used for this problem. This paper, investigates the Static Synchronous Compensator (STATCOM) application to achieve uninterrupted operation of wind turbine equipped with DFIG during grid faults. The simulation has been done in PSCAD/EMTDC framework. View full abstract»

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  • A study of stability of large wind turbine blades

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    The paper extends Hodger-Dowell's partial differential equations of blade motion, by building a new blade model of large horizontal axis turbines including the effects from gravity, pitch action, pre-twist and rotor speed. New equations also build an aerodynamic model using analysis of properties of air density, blade thickness and wind speed. All partial differential equations are approximated by a second-order finite difference approximation and used to simulate the stability of blade by varying parameters. View full abstract»

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  • A discussion on using Empirical Mode Decomposition for incipient fault detection and diagnosis of the wind turbine gearbox

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    Vibration signals from the gearbox of a wind turbine are essentially non-stationary and nonlinear in both time and frequency. Empirical Mode Decomposition (EMD) is an ideal method for dealing with this type of signal. Yet the signal containing the fault information was contaminated by the noise, which contains two different types of white noise and impact noise. This makes it so the vibration signal cannot be processed with EMD directly, since it will produce the spurious IMF (Intrinsic Mode Function). The signal has to be pre-processed before implementing EMD. In fact, a wavelet filter is perfect for white noise de-noising and the morphological filter is suitable for impulse interference. In this paper, a confederative filter, which is combined with the wavelet and morphological filter, is designed for signal preprocessing, and a standard processing program is proposed too. An experimental case shows the accuracy and efficiency of the confederative filter and the process program. View full abstract»

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  • Research on turbulence intensity as an evaluation index for micrositing validation

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    The factors determining the optimal wind turbine type for a site-specific wind farm are 50-year extreme wind speed, mean wind speed and turbulence intensity. Wind climate is highly dependent on the terrain; the process of micrositing should not exclusively focus on the energy yield, but should also aim for the availability and safety of the wind turbine. The validation of micrositing is to double check to make sure that the 50-year extreme wind speed, mean wind speed, incline angle and turbulence intensity meet the wind turbines design requirements in the standards. On the basis of the analysis of micrositing validation process, the present paper focuses on the turbulence intensity as an evaluation index for micrositing validation, and takes a wind project as a case study to illustrate its circuit. View full abstract»

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  • Key technologies analysis of small scale non-grid-connected wind turbines: A review

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    The aim of this paper is to review the key technologies of current used small-scale non-grid-connected wind turbines and highlight future developments of both technologies and application. First, the key technologies are divided into four main parts: mechanical structure, generator, converter system and control system. The international developments and the latest technologies are presented from the view of the four main parts. Next, this paper analyzes the four main parts of the key technologies in detail. The characteristics of HAWT, VAWT and HVAWT, choosing and designing of a generator, the AC-DC rectifier and DC-DC chopper circuits in the converter system and the MPPT based laws used in the control system are thoroughly discussed in this paper. Then, the application of a small-scale non-grid-connected wind turbines is introduced. The three main ways are roof top, stand alone and built-in. Meanwhile, the concept of the renewable hybrid energy system which consists of a wind energy system, a PV solar system and a diesel generator is proposed. The four parts of the current research results are presented: novel power electronics technologies, advanced simulation software, automatic controller and deep cycle battery bank. View full abstract»

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  • Transient analysis of a non-grid-connected wind driven DSEG using Hardware-in-the-Loop simulation based on RT-LAB

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    Internal faults in a wind driven generator can affect the quality of its output power, sometimes even the system's safety. However, the fault experiments are dangerous, thus this paper presents a Hardware-in-the-Loop (HIL) simulation system based on RT-LAB and DSP, which was applied to research the transient behavior of a doubly salient electro-magnetic wind power generator (DEWG) system and the control performance of the controller during unbalanced fault conditions. Meanwhile, the variation characteristics of three-phase voltage, three-phase current, excitation current and output power in the case of single line-to-ground fault and line-to-line fault while the system is in the process of maximum power point tracking (MPPT) are investigated. View full abstract»

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  • The UAE wind turbine performance prediction using wind tunnel airfoil data

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    It's vitally important for wind turbine aerodynamic performance predictions to design and optimize wind turbines. In view of the BEM method's fast speed and widespread use, this paper applies WT_Perf software of NREL to predict the performance on a NREL Phase VI upwind wind turbine. Measurements from the Phase VI of the NREL/NASA Ames wind tunnel test were used for validating the predictions. Performance predictions will vary greatly when data selection changes. Also three-dimensional rotational stall delay should be accounted for in the predictions. The final obtained prediction methods show good agreement with the experiments. Because of their accuracy and straightforward manufacturing, derived methods can be widely used in wind turbine optimization and design of the future research. View full abstract»

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  • A practical method of unit commitment considering wind power

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    In this paper, a dispersed probability distribution model is built based on statistics of wind power forecasting error. Thus, the probabilistic reserve constraints in the analytic expression can be introduced into the traditional unit commitment (UC) model by Gauss function fitting of the distributions of different generations considering wind power. Otherwise, in order to solve the UC problem with these reserve constraints efficiently, this paper presents an improved approach of modifying Lagrangian multipliers based on the concept of average cost in the unit decommitment (UD) method. In addition, the search range and economic indices of units are also improved. A 26-unit system is analyzed to exhibit the effectiveness of the probabilistic reserve constraints and the proposed UD method. View full abstract»

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  • Experimental investigation and analysis for gearbox fault

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    As an important component of a wind turbine drive chain, the high failure rate of the gearbox can have a serious impact on the operation of wind turbine units. The fault diagnosis of the gearbox is therefore important for the safety of wind turbine units. In this paper, a gearbox experiment rig was built, experiments on the gear surface spalling fault were held on the rig under laboratory conditions, the shaft vibration displacement signals were collected, related vibration signals were analyzed by time domain, amplitude domain, frequency domain and wavelet analysis, and the results of different analysis methods were compared. The results show that the waveform of normal and fault signals are similar, the amplitude of the signals will change while the fault happens, and the wavelet analysis is more effective than frequency domain analysis on gearbox fault features extraction. View full abstract»

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  • A study of non-grid-connected wind power industry development path choice based on new institutional economics

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    Non-grid-connected wind power is a brand new field of wind power development, which is closely related to national policy. In its future growth, national policy, or institutional factors will directly influence its direction of development. Employing new institutional economics' basic theories, this paper analyzes non-grid-connected wind power's evolution and development path choice from the view of institutional innovation and institutional change. Then a development mode of non-grid-connected wind power is put forth to accomplish the institutional change according to the characteristics of institutional changes. Under this mode, government should play an active role in economic efficiency and institutional construction to promote sustainable development of wind power. View full abstract»

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  • Application of fiber-reinforced composites in wind turbine blades

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    Wind turbine blades are the key components in the wind power generation system. Fiber-reinforced composites in wind turbine blades are widely used in the development of large-scale wind turbines. The advantages of fiber-reinforced composites and the characteristic of reinforced fibers are introduced. The structure of fiber aggregation is enumerated and their advantages and disadvantages are analyzed. The development of wind turbine blades is presented. View full abstract»

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  • Application of back propagation neural network to fault diagnosis of direct-drive wind turbine

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (211 KB) |  | HTML iconHTML  

    The vibration signals of wind turbines are highly nonlinear and non-stationary due to wind turbine operation conditions that are very complicated. The signals will be more complex when a fault occurs. Aiming at these problems, a fault diagnosis method for direct-drive wind turbine is presented based on back propagation neural network (BPNN). The time-domain feature parameters of vibration signals in the horizontal and vertical direction are considered in the method. Five experiments of direct-drive wind turbine with normal, wind wheel mass imbalance, wind wheel aerodynamic imbalance, yaw and blade break are carried out in laboratory scale. Through analyzing the features of five conditions, the time-domain feature parameters in horizontal and vertical direction of the vibration signal are selected as the input samples of BPNN. By training, the BPNN model can be constructed between feature parameters and fault types. The validity of the BPNN model is verified using test samples. The results indicate that the proposed method has higher diagnostic accuracy. It can used in on-line fault diagnosis of direct-drive wind turbines. View full abstract»

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  • Design of LCL filter for wind power inverter

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    An LCL filter is more and more widely used in wind power inverters. However, it may easily result in instability due to resonance, which makes it difficult for stability control without damping. A voltage oriented control strategy under the dq synchronization reference frame is adopted based on the mathematical model of the three-phase inverter for wind power, and then the characteristics and performance of an LCL filter compared with the L filter are investigated in detail. At the same time, the design of the LCL filter and the influence of system stability with different damping are given. Experimental results have effectively verified the design. View full abstract»

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  • Vibration characteristics on a wind turbine rotor using modal and harmonic analysis of FEM

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    A wind turbine rotor system containing blades has its own characteristics. The vibration characteristics of blades with special airfoil can influence the vibration characteristics of the rotor system. This paper analyzed the vibration characteristics of a wind turbine rotor including blades with two-dimensional airfoil. The Finite Element Method (FEM) is applied to establish the rotor model, with the purpose that the FEM can adjust complex blades airfoils and acquire the details of the blades vibration characteristics. The modal characteristics are extracted based on the wind turbine model established in the laboratory. Using harmonic analysis of FEM, the excitation forces on the blades caused by the stochastic wind load are imposed on the rotor model and the stable response of the rotor system is calculated using ANSYS. Then the vibration characteristics are analyzed and the characteristics of the harmonic response are studied under different phases of the circumferential and axial forces. View full abstract»

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  • Analysis of a new dual-stator doubly salient brushless DC generator

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    This paper presents a new dual-stator doubly salient brushless DC generator (DSBLDCG). The key of the proposed generator is to reduce the voltage and torque ripples. Finite element analysis (FEA) of the generator is carried out to investigate the magnetic field distribution at different rotor positions. Furthermore, flux-linkage and inductance characteristics are also given. The simulation of the generator with three-phase half-wave common anode rectifier circuit is well performed. The results from the finite element analysis verify the theory analysis and the rationality of the generator. It shows that the structure of the dual-stator can decrease the voltage ripple effectively, especially under heavy load conditions. View full abstract»

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  • MPPT of VSCF wind energy conversion system using extremum control strategy

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (485 KB) |  | HTML iconHTML  

    This paper presents the energy conversion optimization control strategy for a horizontal axis variable speed fixed pitch wind energy conversion system, which works in the partial load region. The system uses a variable speed wind turbine (VSWT), driving a squirrel-cage induction generator (SCIG) connected to a grid. Reference to the wind turbine model and its parameters are poorly known, so a new Maximum Power Point Tracking (MPPT) method is proposed based on the extremum seeking control principles. The aim is to drive the average position of the operating point near optimality. Here, the wind turbulence is used as search disturbance instead of inducing new sinusoidal search signals. The Fast Fourier Transform (FFT) processing of some available measures estimate the operating point's distance to optimality. The effectiveness of the proposed MPPT scheme is validated under different operating conditions by numerical simulations. The simulation results prove that this new approach has effectively suppressed the system vibration and enhanced system dynamic performance. View full abstract»

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  • Development and prospects of offshore wind power

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    Offshore wind power is a useful means to ensure the safety of energy consumption, and to increase the economy and to react to the petroleum crisis. Following with the advance of wind power technology, as well as the advantages in abundance of wind resources, comparatively stable wind speed in the sea, fewer developing interest relative sides, and non-trying for land with other projects, large scale of offshore wind farm building becomes a new trend for wind power industry development. In this journal, the development of offshore wind power was summarized. Then the benefits to development of offshore wind power are analyzed. The current situation of offshore wind power of Europe, North American and Asia are also introduced. At the end, the offshore wind energy trends from shallow to deep sea and technology are prospected. View full abstract»

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  • Wind farm modeling based on BP neural network

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    Wind farm modeling is an important research topic, but the traditional mechanism modeling method is difficult to get accurate models. However, performance of the neural network model is superior for identification and approximation of complex nonlinear systems. Especially, the BP network has been widely and successfully used in the engineering field. This paper gives a brief introduction to the BP network, and the network model is used for modeling of wind farms to prove the feasibility of BP model in the field of wind power. View full abstract»

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  • Fatigue load simulation for foundation design of offshore wind turbines due to combined wind and wave loading

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    Wave- and wind-induced fatigue load plays an important, often crucial role in the design of wind turbine supporting structures. This paper presents a practical procedure of fatigue load simulation for foundation design due to combined wind and wave loading in time domain. The distributions of mean wind speed and wind direction, as well as the wave height and wave period are taken into account. Correlation between wind and wave is considered by introducing the scatter diagram from oceanography. The harmony superposition method (HSM) is applied to simulate fully correlated random time series of wind velocity, from which aerodynamic loads can be obtained. The aerodynamic loads on the wind turbine rotor are determined using the blade element momentum method (BEM), which is computationally efficient but with good precision. The ocean wave model suggested by Longuet-Higgins is adopted, by which an irregular wave can be simulated based on the linear wave theory (Airy theory). Wave loads are finally generated by using the Morison equation. The offshore wind turbine tower is modeled as a discrete multi-degree-of-freedom system, with a lumped mass at the top of tower, representing the nacelle and blades. The bottom of the tower is connected to springs to introduce the effect of soil stiffness. The fatigue load spectrum is extracted by using the rain flow counting method. Through comparison with the capacity spectrum, the situation whether the design requirement is satisfied or not can be verified. Numerical examples are presented in the paper to demonstrate the feasibility of the current procedure. The sensibility of fatigue load due to variation of simulating parameters including water depth and soil stiffness is also numerically studied. View full abstract»

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