风电机组选型分析

介绍了双馈风电机组和直驱风电机组的工作原理和性能特点,并在此基础上对2种机组进行了定性分析和有关参数的定量比较,结合各自的实际运行情况,给出了风电场风电机组初步选型原则：双馈风电机组技术成熟．运行经验丰富,一段时期内可作为首选机型：技术经济条件允许时再结合具体情况考虑选用直驱尤其是永磁直驱风电机组,是未来风电场机型选择的新趋势。     

大规模风电接入后电网离线分析

依托DIGSILENT仿真软件,搭建双馈异步风机和永磁直驱风机仿真模型。通过建立低电压穿越功能模型,对2020年前华东电网夏季高峰运行方式,进行大规模风电接入后的短路电流计算和故障校核方式的仿真分析,用以验证风电机组的运行特性。结果表明:对于双馈风机,由于对不对称保护的特殊要求,电网不对称故障引起风电机组跳机(无低电压穿越能力)或Crowbar动作(有低电压穿越能力)的范围远大于对称故障,应采用不对称故障校核方式。对于直驱风机,直流母线越限保护动作与否,只与母线电压的降落幅度有关,仍应采用常规的对称故障校核方式。     

并网永磁直驱风电机组故障穿越能力仿真研究

随着电力电子器件成本下降,拥有全功率变换器的永磁直驱风机成为各国关注热点。风电场容量不断增大,要求风电机组具有故障穿越能力。本文以直驱同步风电发电机组为研究对象,利用matlab/simulink搭建了直驱同步风电机组的动态数学模型,对直驱同步风电机组故障穿越能力进行仿真研究,试验结果表明：在风电场接入点发生故障时,直驱同步风电机组具有故障穿越功能。尤其在电网发生电压跌落时,直驱风机能为系统提供一定的无功支撑。有效防止系统电压过多降落。提高了系统故障运行的稳定性。     

多机型风电机组机网扭振的模型与机理

分别针对风电场的定桨失速型、直驱式永磁型和双馈异步型风力发电机组3种主流机型的机网扭振机理进行了分析.建立了风力发电机组机网扭振研究的小信号分析模型,包括风力机的机械旋转系统模型、发电机模型、控制模型及电网模型.其中机械旋转系统包括风力机的桨叶、高速轴、齿轮箱、低速轴和发电机转子,等效为3个集中质量块-弹簧模型;发电机、电网及控制模型均在dq坐标系下建立.建立了整个模型的状态方程.通过仿真研究了上述3种机型风电机组机网扭振的单机对无穷大仿真模型,利用输电线路首端三相短路故障激发风电场和电网间的机网扭振现象,得到了转速和转矩的扭振曲线,扭振频率与计算得出的风力发电机组机械旋转系统固有频率吻合,验证了模型的准确性.     

面向次同步振荡的直驱风电机组阻抗频率响应特性辨识

针对直驱风电机组参数未知时,其阻抗模型解析式难以获取的问题,提出曲线拟合辨识机组次同步频段内的阻抗频率响应特性的新思路.首先提出一种基于多项式拟合的直驱风电机组阻抗模型频率响应特性辨识方法,利用曲线拟合取代传统解决思路中的传递函数辨识环节,降低辨识难度.然后,利用已有的阻抗分析方法,基于辨识模型展开直驱风电机组次同步振...     

基于AMESim的风电机组建模和仿真

根据双馈型风电机组的结构,基于多学科系统建模仿真平台AMESim建立了包含叶轮气动特性、传动链、双馈电机及其控制的整机模型。研究了风电机组将风能转换为电能的过程,模拟了变速恒频控制可实现并网要求。     

直驱型风电机组市场近况

本文介绍了直驱型风电机组的两种技术路线,以及该类型机组与双馈型风电机组的优劣势比较,同时,分析了目前直驱型风电机组的市场情况。     

风电场变速恒频风力发电机之间谐波扰动研究

变速恒频风力发电机在工作过程中会产生谐波,当双馈异步风力发电机风速达到切入风速时,并入电网的双馈异步风力发电机与其他直驱永磁风力发电机之间会因为功率传递产生谐波扰动,文章研究分析了此问题,并根据瞬时无功理论和其他风力发电有关理论在Matlab中进行建模和仿真,仿真结果表明亚同步发电状态双馈异步风力发电机会因为功率传递受到正常工作直驱风力发电机的谐波扰动,扰动会随着风力发电机数量的增多而加剧。     

直驱与双馈风机技术流派对比分析

当前,随着我国风电行业的发展壮大,国产风电技术装备行业也取得长足进步,风电设备国产化程度日益提高引起了项目工程造价持续降低,因此,风机选型对于保障风场运行安全及降低维修成本起到至关重要的作用.直驱与双馈风机技术流派分别具有各自特点,将对我国风电产业发展起到重要影响作用.     

风力发电机组电压波动与闪变分析研究

风力发电机组与中压电网连接,中压电网通常连接有其它波动性负荷,在被测风力发电机组输出端可能引起显著的电压波动,电网特性决定了风力发电机组产生电压波动的程度。为了避免电网实际电压波动对测量点闪变的直接影响,文章在研究了标准推荐的闪变值计算方法基础上,分别计算直驱永磁型风力发电机组和双馈异步型风力发电机组的闪变值,分析风力发电机组闪变值的影响因素。对比虚拟电网计算闪变值和理想电压条件下测量闪变值,验证虚拟电网方法的有效性。     

异步风电机组的短路特性仿真研究

以PSCAD/EMTDC为平台建立了仿真模型,分析了以恒速异步风力发电机组为主的风电场并网运行的不同故障情况下的短路特性。仿真结果表明,影响短路特性的主要因素有故障类型、故障点、控制策略、风速等。因此,应针对风电场不同的短路特性采取相应的保护措施,以提高电网的稳定性。     

Evaluation of different wind fields for the investigation of the dynamic response of offshore wind turbines

As the size of offshore wind turbines increases, a realistic representation of the spatiotemporal distribution of the incident wind field becomes crucial for modeling the dynamic response of the turbine. The International Electrotechnical Commission (IEC) standard for wind turbine design recommends two turbulence models for simulations of the incident wind field, the Mann spectral tensor model, and the Kaimal spectral and exponential coherence model. In particular, for floating wind turbines, these standard models are challenged by more sophisticated ones. The characteristics of the wind field depend on the stability conditions of the atmosphere, which neither of the standard turbulence models account for. The spatial and temporal distribution of the turbulence, represented by coherence, is not modeled consistently by the two standard models. In this study, the Mann spectral tensor model and the Kaimal spectral and exponential coherence model are compared with wind fields constructed from offshore measurements and obtained from large‐eddy simulations. Cross sections and durations relevant for offshore wind turbine design are considered. Coherent structures from the different simulators are studied across various stability conditions and wind speeds through coherence and proper orthogonal decomposition mode plots. As expected, the standard models represent neutral stratification better than they do stable and unstable. Depending upon the method used for generating the wind field, significant differences in the spatial and temporal distribution of coherence are found. Consequently, the computed structural design loads on a wind turbine are expected to vary significantly depending upon the employed turbulence model. The knowledge gained in this study will be used in future studies to quantify the effect of various turbulence models on the dynamic response of large offshore wind turbines.     

尾缘襟翼结构参数对大型风机气动性能影响的仿真研究

利用FAST仿真平台,研究了大型风机智能叶片的尾缘襟翼结构参数对叶片载荷抑制和功率捕获等气动性能的影响。仿真结果表明:尾缘襟翼位于叶尖部位时,在不同风况下,襟翼对叶片具有较好的降载效果,低风况及过渡风况下,功率捕获损失较小;增加襟翼占弦比、长度和摆角范围,在低风况及过渡风况下,可进一步提高叶片的降载能力,但存在一定的功率损失;在高风况下,襟翼占弦比、长度和摆角范围均存在提高叶片降载能力的最佳值,且这3个参数的变化对功率捕获无影响。     

Seismic response of floating wind turbines due to seaquakes

Vertical seismic waves, which are primarily due to pressure waves in the ground, can propagate with the same intensity in the seawater and impact floating bodies such as floating wind turbines (FWTs). Part of this wave can further propagate in the tower and generate large vertical accelerations in the nacelle. This paper presents a methodology for computation of the pressure waves generated by vertical earthquake shaking, referred to as seaquake, its impact on submerged bodies, and the induced dynamic response in the structure. A FWT concept with catenary mooring is used for the assessment of the effects of earthquake shaking. The pressure during a seaquake is determined using a 2D acoustic finite element (FE) model in Abaqus. The acoustic model is benchmarked against a 1D analytical solution. The response due to the environmental loads, namely, wind, current, and waves, is also studied and used as a reference for assessment of the relative significance of the seaquake. Considerable vertical accelerations can occur in the nacelle due to amplification of the platform accelerations through the tower. It is shown that this acceleration could exceed a commonly used operational limit range of 0.2 g to 0.3 g even for moderate accelerations at the seabed. This indicates that earthquake loading should be considered in the design of FWTs in seismic regions. The mooring tensile forces, due to motion of the platform during a seaquake, do not exceed the design tension computed for the extreme environmental conditions. However, the leeward mooring lines could experience zero tension, which could cause snap tension.     

大型风电机组气动响应特性分析

针对大型风电机组柔性多体塔架-叶片耦合结构气动响应问题,文章提出了在不同偏航角度下的分析方法。根据该方法的流程图,建立了大型风电机组柔性多体塔架-叶片耦合结构动力学模型。采用谐波叠加法计算气动载荷分布,考虑塔影效应与风剪切的影响,得出诱导因子时程曲线与气动响应均值。计算结果表明:轴向与切向诱导因子变化较小,尾流稳定;偏航角逐渐增大导致塔顶顺风向位移均值减小,根方差值增大。该结果为大型风电机组运行过程中监测状态参数的变化与流体动力学分析提供了参考。     

A frequency domain approach to wind turbines for flicker analysis

Wind turbines may have an important impact on power quality. Flicker is a more serious issue for fixed-speed wind turbines because these turbines produce electric power following the variations of the incident wind. During continuous operation, wind variations will result in power fluctuations and consequently in voltage fluctuations. It is necessary to evaluate wind turbines flicker emission level, and traditionally time domain simulations have been used to perform the analysis. This paper presents a complete frequency domain model to study flicker produced during wind turbines continuous operation. The model includes a realistic wind speed model as observed by the wind turbine and also a frequency domain induction generator model is presented. The frequency domain model has been compared with a time domain model. The frequency domain approach, as shown in the paper, may be very useful for flicker analysis in electric networks.     

Power system frequency response from fixed speed and doubly fed induction generator‐based wind turbines

Throughout Europe there is an increasing trend of connecting high penetrations of wind turbines to the transmission networks. This has resulted in transmission system operators revising their grid code documents for the connection of large wind farms. These specifications require large MW capacity wind farms to have the ability to assist in some of the power system control services currently carried out by conventional synchronous generation. These services include voltage and frequency control. It is now recognized that much of this new wind generation plant will use either fixed speed induction generator (FSIG)‐ or doubly fed induction generator (DFIG)‐based wind turbines. The addition of a control loop to synthesize inertia in the DFIG wind turbine using the power electronic control system has been described. The possibility of deloading wind turbines for frequency response using blade pitch angle control is discussed. A pitch control scheme to provide frequency response from FSIG and DFIG wind turbines is also described. A case study of an FSIG wind turbine with frequency response capabilities is investigated. Copyright © 2004 John Wiley & Sons, Ltd.     

An experimental study of the two-staged wind turbines

In order to improve the torque performance of the propeller type wind turbine, and to increase the relative rotational speed of the generator, two-staged wind turbines were proposed. The experimental results of a wind tunnel test showed that self-starting characteristics of two-staged co-axial type were improved by attached front wind turbines for two bladed main wind turbine, and the relative rotational speed of counter-rotating type was increased.Then, a counter-rotating type trial machine was constructed and a wind tunnel test was also conducted. The test result demonstrated the technical possibility of conterrotating type wind powered generator.     

Comparison of the response of doubly fed and fixed-speed induction generator wind turbines to changes in network frequency

Synchronous and fixed-speed induction generators release the kinetic energy of their rotating mass when the power system frequency is reduced. In the case of doubly fed induction generator (DFIG)-based wind turbines, their control system operates to apply a restraining torque to the rotor according to a predetermined curve with respect to the rotor speed. This control system is not based on the power system frequency and there is negligible contribution to the inertia of the power system. A DFIG control system was modified to introduce inertia response to the DFIG wind turbine. Simulations were used to show that with the proposed control system, the DFIG wind turbine can supply considerably greater kinetic energy than a fixed-speed wind turbine.     

Investigating the possibility of using different hub height wind turbines in a wind farm

Many researchers have focused on the layout design of a wind farm using the computational methods. Most of previous researches focused on relevant large cell size and using same hub height wind turbines. In this paper, the authors investigate the possibility of using different hub height wind turbines in a wind farm. A limited area (2?km?×?2?km) with constant wind speed and direction is considered as the potential wind farm area, and a nested genetic algorithm is used as optimisation algorithm. Two different hub height wind turbines are introduced with two different cell sizes. Power output, cost, payback period, and total profit are selected as evaluation criteria when comparing the layouts with same hub height wind turbines with the layouts with different hub height wind turbines. The results demonstrate that it is feasible and possible to use different hub height wind turbines in a wind farm.