Volume 38,Issue 1,2015 Table of Contents

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  • 1  A new control design for grid integration ofDFIG wind farm with VSC-HVDC
    YANG Tao LIU Guoping HUANG Miao WEN Yiyu LIAO Yong WANG Guodong
    2015, 38(1):1-11. DOI: 10.11835/j.issn.1000-582X.2015.01.001
    [Abstract](2132) [HTML](359) [PDF 12.12 M](1044)
    Abstract:
    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.
    2  Dynamic characteristics analysis of megawatt wind turbine drive train
    ZHANG Shenglin SONG Chaosheng ZHAI Hongfei BAI Houyi ZHU Caichao
    2015, 38(1):12-19. DOI: 10.11835/j.issn.1000-582X.2015.01.002
    [Abstract](1739) [HTML](473) [PDF 7.81 M](1092)
    Abstract:
    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.
    3  Load modling and analysis of wind turbine under consideringthe space coordinate transformation
    HAN Huali TAO Youchuan WEN Maoshi XU Xiangyang
    2015, 38(1):20-26. DOI: 10.11835/j.issn.1000-582X.2015.01.003
    [Abstract](2043) [HTML](969) [PDF 6.94 M](1371)
    Abstract:
    Based on coordinate transformation and mechanical analysis, load transformation between blade root and rotor coordinate system for wind turbine is derived.And an analysis model closer to actual working condition is established.Taking a 5 MW wind turbine as analysis object, analyzing results of the new model, traditional simplified model and GH Bladed model are compared, and results are good enough to validate this new model has higher reliability and accuracy.In addition, based on analyzing to load component, through access to instance data of each factor in process of coordinate transformation, the impact of each factor can be accurately analyzed, which is of great significance to control and reduce load.
    4  Open motion control architecture of wind turbineand main controller design
    YANG Jiancheng FU Xinghua
    2015, 38(1):27-36. DOI: 10.11835/j.issn.1000-582X.2015.01.004
    [Abstract](2170) [HTML](488) [PDF 10.37 M](2564)
    Abstract:
    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.
    5  Design of networking condition monitoring andfault diagnosis for wind turbine transmission system
    MA Jinghua TANG Baoping HAN Yan
    2015, 38(1):37-44. DOI: 10.11835/j.issn.1000-582X.2015.01.005
    [Abstract](2247) [HTML](342) [PDF 10.30 M](1297)
    Abstract:
    In order to solve the incipient fault diagnose problem of the transmission system, a networking condition monitoring and failure diagnosis system based on B/S and C/S hybrid architecture for wind turbine transmission system is designed in the paper. Firstly, the paper analyzes the demands of condition monitoring and fault diagnosis system for wind turbine transmission system, and designs its overall framework and function modules. Then, combining with the data acquisition equipment, by the .NET and SQL Server platform, the paper designs condition monitoring and failure diagnosis system for wind turbine transmission system, which includes the functions of networking data acquisition, remote condition monitoring, signal analysis, fault diagnosis and database as well. The system has been successfully applied to a condition monitoring and fault diagnosis of wind turbine transmission system.
    6  Modeling and simulation of a grid connected wind turbine withdoubly fed induction generator
    DU Jing ZHOU Yunpeng LI Chengwu
    2015, 38(1):45-55. DOI: 10.11835/j.issn.1000-582X.2015.01.006
    [Abstract](2026) [HTML](1048) [PDF 13.30 M](1638)
    Abstract:
    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.
    7  The analysis of rotating blades effect onwind turbines macelle wind measurement
    MO Ruiyu ZHANG Kai TAO Youchuan
    2015, 38(1):56-60. DOI: 10.11835/j.issn.1000-582X.2015.01.007
    [Abstract](1805) [HTML](330) [PDF 5.92 M](1314)
    Abstract:
    To improve the accuracy of wind measurement, computational fluid dynamics is adopted to simalate the impact of wind turbine blades with and without T-spoilers on the outflow field distribuation and the wind speed and direction measurement on the top of macelle. The simulation is arried out on a 5 MW wind turbines when the rated wind speed is 10.5 m/s and the rated speed of blades is 11.34 r/min. The calculation results show that the blades with T-spoilers have greater impact on the accuracy of anemometer and wind vane on the top of nacelle. Therefore,it’s recommended to move forward the wind measurement equipment 0.3 m and elevate them 1 m relative to the original position so that the measurement accuracy meets the design requirements.
    8  Independent pitch control strtegy anlysis of MW wind turbine
    JIN Xin LI Lang HE Yulin YANG Xiangang
    2015, 38(1):61-67. DOI: 10.11835/j.issn.1000-582X.2015.01.008
    [Abstract](1856) [HTML](445) [PDF 7.51 M](1634)
    Abstract:
    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.
    9  Remote on-line vibration test for multi-megawatt wind turbine
    HUANG Huaqing DU Xuesong LIU Huachao BAI Houyi ZHU Caichao
    2015, 38(1):68-73. DOI: 10.11835/j.issn.1000-582X.2015.01.009
    [Abstract](1527) [HTML](991) [PDF 7.62 M](1431)
    Abstract:
    As the key components of the wind turbine transmission, wind turbine drivetrain is always working under the complex and time-varing conditions, like flexible tower supporting, variable wind and changing load. Thus drivetrain is no wonder the weakest part for the wind turbine and its vibration characteristics determine the reliability and operating life of the wind turbine. This paper proposes a remote on-line test method for drivetrain vibration based on an intellectual monitoring unit named WindCon. The vibration characteristics of the commonly used multi-megawatt wind turbine are summoned through analyzing the collected data in different working conditions. The wind field results show that the vibration of drivetrain is relatively complex, and it’s mainly manifested as a combination vibration of torsion, bending, and waving. Main frequencies of vibration of mainshaft, gearbox, and other parts in drivetrain are gear meshing frequencies and shaft rotating frequencies of each transmission stage especially high speed stage, and are accompanied by rotating frequencies modulation.
    10  Evaluation and analysis on the extreme load of wind turbine blade
    PANG Xiaoping LIANG He CHEN Jin DENG Bo
    2015, 38(1):74-79. DOI: 10.11835/j.issn.1000-582X.2015.01.010
    [Abstract](1640) [HTML](507) [PDF 6.87 M](1164)
    Abstract:
    According to the international standard of German GL 2010, a wind turbine of 850 kW is applied to the corresponding wind power generation unit and its situation of pneumatic rated power and sympathetic vibration is analyzed with Bladed software. The result verifies the reliability of wind turbine in operation. Further, after all the wind regimes in GL standard are calculated and analyzed comparatively, the extreme wind regimes which mainly influence the aerodynamic performance of the wind blade are obtained, namely, Dlc4.2b, Dlc1.3a, etc. Later on, the evaluation criteria of wind turbine blade taking the load of blade root as standard are established and implemented with the built-in demo data of Bladed software to testify its generality. Then based on the above evaluation criteria, extreme loads of the 850 kW’s blade root is computed and it’s found the extreme swing load is 353 663 N·m, which is 2.5% lower than its designed value. The result verifies the security of the blade in operation and the reliability of the evaluation criteria.
    11  Arrangement and design of main bearing for wind turbine
    YU Liping SHI Yiping LIU Ruifeng
    2015, 38(1):80-86. DOI: 10.11835/j.issn.1000-582X.2015.01.011
    [Abstract](2060) [HTML](647) [PDF 6.89 M](2298)
    Abstract:
    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.
    12  Junction stiffness analysis and vibration noise prediction of wind power speed-increase gearbox
    LIN Tengjiao GUO Jin LIU Bo SHEN Tao
    2015, 38(1):87-94. DOI: 10.11835/j.issn.1000-582X.2015.01.012
    [Abstract](1830) [HTML](310) [PDF 9.09 M](1218)
    Abstract:
    In order to study the vibration characteristics and radiation noise of wind power speed-increase gearbox, a torsional vibration model of wind power speed-increase gearbox is established based on the analysis of supporting stiffness of bearing and contact stiffness of gear pairs. By solving the vibration differential equation with the help of Matlab, the frequency and corresponding vibration mode are obtained. With taking stiffness excitation, error exaction and meshing impact exaction into account, the dynamic finite element model of speed-increase gearbox is set up, and the dynamic response simulation is carried out. Regarding vibration displacement of the nodes on gearbox surface as boundary condition, an acoustic boundary element model of speed-increase gearbox is built. The surface acoustic pressure of gearbox and the radiation noise of field points are solved by the direct boundary element method. The results show that there is a great difference between torsion frequency and excitation frequency of wind power speed-increase gearbox, and so the resonance doesn't occur. The maximum structural noise and radiation noise mainly appear near the double octave of the gears meshing frequency of high-speed grade.
    13  Dynamics research of wind turbine gearbox with herringbone planetary gear
    SHI Wankai QIU Hongyou HAN Zhenhua QIN Pengfei
    2015, 38(1):95-102. DOI: 10.11835/j.issn.1000-582X.2015.01.013
    [Abstract](1858) [HTML](311) [PDF 9.42 M](1346)
    Abstract:
    Based on the method of gear system dynamics and Lagrange equation, a translational-rotational coupling dynamic model of the herringbone planetary gear sets is built and dynamic analysis is carried out. The analysis results have guiding meanings for the design of herringbone planetary gear transmission system. Herringbone gear is treated as two helical gears in the model, and gear train elastic coupling, load inertia and stagger angle between the left and right helical gears is considered. The load sharing coefficients of the system are obtained through calculation, and the impact of stagger angle and coupling torsional stiffness between the left and the right helical gears on the load sharing characteristic is analyzed. The analysis results show that when stagger angle is π/2, the load sharing coefficients are the best, and coupling torsional stiffness between the left and the right helical gears has litter influence on the load sharing coefficients.
    14  Dynamic analysis of wind turbine gearbox
    SUN Zhongkui SUN Yizhong HE Aimin WANG Shaoli
    2015, 38(1):103-109. DOI: 10.11835/j.issn.1000-582X.2015.01.014
    [Abstract](1652) [HTML](535) [PDF 8.21 M](1306)
    Abstract:
    By inputting reduced matrix of stiffness and mass, a dynamic model including flexible housing, ring gear and carrier for a 3 MW wind turbine gearbox is established based on MASTA. And analysis results show that the kinetic percentage of housing is maximum near the gear mesh frequency and response is maximum at the 1st mesh frequency of HSS gear. The analysis results show certain agreement with vibration test results. This paper can provide reference for avoiding vibration in gearbox design.
    15  Multi-objective dynamic optimization design of high-power wind turbine gearbox
    SUN Wei LI Xiang WEI Jing HU Xinglong ZHANG Aiqiang
    2015, 38(1):110-119. DOI: 10.11835/j.issn.1000-582X.2015.01.015
    [Abstract](1557) [HTML](383) [PDF 14.24 M](1199)
    Abstract:
    A dynamic model of NGW helical planetary gear transmission for high-power wind turbine gearbox is established by considering these factors as errors of gears and time-varying mesh stiffness by using mass centralized method. Moreover, the random wind velocity is simulated as external seismic excitation making the results more conform to practical condition. And on this basis, this system is optimized for minimum gearbox volume and minimum component torsional acceleration with the restriction of reliability and strength restrain. The result indicates that the optimized parameters make gear transmission lightweight and the dynamic property improved so as to reduing vibration and noised.
    16  Analysis of gear micropitting for megawatt-class wind turbine gearbox
    SONG Yongle LI Guangfu CHEN Xiaojin DAI Xianwu XIAO Denglu
    2015, 38(1):120-125. DOI: 10.11835/j.issn.1000-582X.2015.01.016
    [Abstract](1983) [HTML](0) [PDF 5.97 M](1579)
    Abstract:
    Gear micropitting phenomenon is common in megawatt-class wind turbine gearbox because of the hard operating environment and complicated load case. More and more attention has been paid to it during recent years. Main factors influencing gear micropitting, such as surface roughness, modification coefficient, oil temperature, are discussed in this paper according to ISO/TR 15144—1:2010. Reasonable values for the factors are suggested and software for calculating micropitting is developed. Based on observation and discussion, measures for reducing gear micropitting risk in wind turbine gearbox design are proposed.
    17  Calculation of micro-pitting load capacity of gears for wind power based on elastohydrodynamic lubrication contact theory
    XIONG Yongqiang SUN Yizhong ZHANG Hechao
    2015, 38(1):126-132. DOI: 10.11835/j.issn.1000-582X.2015.01.017
    [Abstract](1828) [HTML](383) [PDF 6.59 M](1170)
    Abstract:
    The computation of a micro-pitting load capacity of gears for wind power is carried out by a model based on the numerical thermal elastohydrodynamic lubrication (TEHL) contact theory. The difference of local lubricant film thickness and safety factor against micro-pitting between TEHL and ISO/TR 15144—1 are compared. The oil film pressure distributions, film shapes, temperature distributions are calculated under some varied points on the path of contact. The results show that calculation of micro-pitting load capacity of gears of wind power based on TEHL contact theory is feasible; the local lubricant film thickness calculated by TEHL contact theory is less than by ISO/TR 15144—1; and it is unnecessary to consider the pressure distributions and contact pattern change caused by TEHL when determining the modifications of main gears of wind power using loaded contact analysis.
    18  Approaches to enhance power density of gearboxes for wind turbines
    LIU Zhongming
    2015, 38(1):133-139. DOI: 10.11835/j.issn.1000-582X.2015.01.018
    [Abstract](1749) [HTML](455) [PDF 8.02 M](1139)
    Abstract:
    Based on pitting strength, some approaches to enhance power density of gearboxes for wind turbines are discussed. The calculation load is greatly reduced by power division. Allowable stress numbers are effectively increased by improving property of quality materials, precision heat treatment or shot peening. Load capacities can be also obviously enhanced by improving the tooth shape of morphology optimization of tooth root, tooth correction or superfinishing of tooth surface. The center distance is effectively decreased by minishing minimum allowable safety factor or enlarging face width. The power density of gearbox can be further improved by means of structure optimization of planet carrier or uniform load of planetary gear transmission.
    19  Worm wheel grinding method of convex pitch line non-circular gear
    HE Kun LI Guolong ZHOU Hongqu XIA Dong ZHANG Wei
    2015, 38(1):140-147. DOI: 10.11835/j.issn.1000-582X.2015.01.019
    [Abstract](1604) [HTML](315) [PDF 7.62 M](1050)
    Abstract:
    To overcome the precision machining difficulty of non-circular gear, a convex pitch curve of non-circular gear and worm grinding method is presented. Firstly, worm wheel is reduced to rack cutter and a rack machining convex pitch curves of non-circular gears sport model is set up. Then based on the structure of CNC worm wheel grinding machine tools and machining principle, electronic gear box of machine tools is designed and active and following axes are planned. At the mean time, the synchronous coefficient of machine tools between synchronization is deduced by machining principle of equal arc-length, and interaction models of grinding are established. At last, the worm wheel manual presetting cutter methods with non-circular gear are given and worm grinding wheel mounting angle, axial position and axial location parameter can be adjusted along the gear.
    20  The analysis of China wind power industry
    WANG Changlu WANG Weigong ZHANG Liyong QIAO Xuetao
    2015, 38(1):148-154. DOI: 10.11835/j.issn.1000-582X.2015.01.020
    [Abstract](2328) [HTML](675) [PDF 6.59 M](2388)
    Abstract:
    The development course of China wind power industry is reviewed by six stages. National policies on wind power industry are elaborated from the aspects of laws & regulations, planning, finance & taxation and electrovalence policy. And these policies have played an important supporting and regulating role in the development of wind power industry. The development status of China wind power industry is analyzed based on wind turbine installed capacity, wind power output and their growth rate. It is explained that national wind turbine manufacturers have kept developing and become strong by the data of new global installed capacity share of mainland wind turbine manufacturers in 2013 and the new global market share of 8 domestic enterprises among the world top 15 wind turbine manufacturers. But there are still 5 key problems which influence the development of national wind turbine need to be solved, including lack of top-level design, abandon and restriction wind power seriously, lack of R&D abilities, some of the key parts relying on imports and wind turbine facing a quality guarantee dilemma. Taking Sinovel Wind Group Co. Ltd. and Xinjiang Goldwind Sci & Tech Co. Ltd., the two leading companies as an example, their performance is analyzed and it’s pointed out that the wind industry must keep vigilant after the overspeed development. The enterprises should try to avoid neglecting cultivating their inner core competitive ability, including technology advancements and products reliability. Occupying the market with low price competition and expanding blindly is also not desirable. At last, the development prospects of our country’s wind power industry are analyzed and three proposals are put forward.
    21  Research and developments of manufacturing technology onwind turbine gearbox
    XUAN Anguang ZHU Caichao
    2015, 38(1):155-160. DOI: 10.11835/j.issn.1000-582X.2015.01.021
    [Abstract](1647) [HTML](468) [PDF 4.53 M](1571)
    Abstract:
    The manufacturing quality and technology of gearbox, which is a core component, is the key guarantee for the superior performance of wind turbine. Wind turbine gearbox manufacturing is a comprehensiveness technique involved multiple disciplines. To realize the digital lean manufacturing, the in-depth research on the fundamental process theory and the process control method should be carried out by taking full advantage of the existing techniques. Also, some new technologies, new processes and new materials should be investigated and applied. By considering the structural features and the actual operational condition for wind turbine gearbox and combining production practices, the requirements and characteristics of the process techniques are summarized. The research state, existing problems, applications and development tendency of high-performance wind turbine gear manufacturing, housing manufacturing and planet carrier manufacturing are analyzed. Then some methods are proposed to improve the manufacturing efficiency and control the heat treatment deformation. Finally, the test techniques for wind turbine are introduced. It has project practical significance for the manufacturing of wind turbine gearboxes.

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