基于变桨距控制策略的异步风电机组暂态稳定性研究

为了提高和改善在电网故障下并网风电机组的暂态稳定性,该文以并网笼型异步风力发电机组为例,考虑风力机传动链柔性带给机组振荡的影响,在典型变桨控制策略的基础上提出了一种增加以风力机转速为控制量的分阶段控制策略.通过建立并网异步风力发电机组的电磁暂态模型,基于Matlab/Simulink仿真平台,应用改进的变桨距控制策略,对电网三相对称短路故障下并网异步风力发电机组的暂态运行特性进行了仿真,并将其结果和多种不同变桨控制策略以及无功补偿策略的结果进行了比较.仿真结果验证了该文提出的变桨距控制策略能有效改善风力发电机组的暂态稳定性.     

含无功补偿装置的风电并网系统 暂态电压稳定性研究

针对大规模风电并网后系统的暂态电压稳定性问题,阐述了暂态电压失稳的机理以及暂态电压稳定性的分析计算方法,介绍了2种重要的无功补偿装置SVC和STATCOM。采用BPA软件对国内某一实际电网进行了仿真分析,结果表明,风速变化和系统发生短路故障均会对系统的暂态电压稳定性造成影响,导致系统的电压水平降低。装设SVC或STATCOM对系统电压均有支撑作用,且STATCOM对电压的支撑作用更加明显。     

PSAT应用于风电系统暂态稳定性研究

  目的  为了研究各风电系统的暂态稳定特性及各风电机组的低电压穿越能力,同时讨论无功补偿容量的加入对各风电系统稳定性的影响。  方法  在PSAT平台上建立了风速、换流器和风力发电机的数学模型,并利用三机九节点包含风力机组的电力系统网络模型,在三相短路故障情况下用时域仿真法对这个网络进行了仿真。  结果  获得了直驱风电系统、双馈风电系统、恒速恒频风电系统在不同母线短路故障持续时间下的电压曲线或功角曲线。  结论  得出了不同机组类型,不同扰动类型,以及不同持续时间下,各风电系统稳定性不同的结论。     

恒速风电机组对电网暂态电压稳定性的影响

基于恒速风电机组的结构,给出风电机组各部分的数学模型,利用仿真软件DIgSILENT/PowerFactory建立恒速风电机组的动态模型,并利用该模型在WSCC 3机9节点算例中仿真恒速风电机组并网运行时因风速变化引起的电网电压波动,通过极限切除时间分析恒速风电机组并网对电网暂态电压稳定性的影响,并与接入相同容量的同步机组进行比较。结果表明,恒速风电机组的接入降低了电网的暂态电压稳定性,且接入恒速风电机组装机容量越大,电网的暂态电压稳定性越差。由此提出改善恒速风电机组并网后电网暂态电压稳定性的建议。     

基于转子串联动态电阻的自适应双馈风电机组低电压穿越方案

针对基于转子串联电阻实现双馈风电机组低电压穿越的保护方式,在阻值选择时转子电流的限制效果与故障期间功率可控性之间存在矛盾的问题,通过对转子串电阻保护的理论分析,提出一种结合故障期间自适应选择转子串联电阻阻值和切换转子变换器控制模式的低电压穿越方案,能够实现根据电压跌落深度选择串联阻值且于不同故障区间内自适应切换阻值的串联动态电阻,使整个故障过程中风机处于受控状态,故障穿越更平稳,具有更好的暂态特性。PSCAD仿真结果表明,该方案具有较好的性能。     

并网异步风力发电机组模型及参数对其暂态稳定性的影响

建立了笼型异步发电机考虑定子电磁暂态的详细模型、忽略定子电磁暂态的简化模型、同时忽略定转子电磁暂态的稳态模型以及一个和两个质量块的风力机轴系模型.针对上述不同组合的5个风力发电机组模型,利用Matlab/Simulink对发电机端部发生三相短路故障情况下的机组暂态行为进行了仿真比较,并通过时域仿真求取了风力机组不同模型下机组故障临界切除时问.结果表明,采用不同风力机组模型对机组暂态稳定性分析结果有很大影响,发电机简化模型和两个质量块的风力机轴系模型较为合适.最后,以提出的合适模型为例,详细研究了风力机模型参数对机组暂态稳定性的影响.     

风电机组偏航制动器制动稳定性分析

针对风电机组偏航制动器制动不稳定问题,基于ABAQUS软件开展偏航制动器制动稳定性分析。运用复特征值分析法和不稳定倾向系数TOI值,分析制动压力、摩擦系数、偏航速度、弹性模量以及开槽方式等对制动稳定性的影响。基于全因子试验及Design-expert软件建立不稳定倾向系数TOI值响应面模型,并开展相关参数优化。研究表明：对制动稳定性具有显著影响的因素是摩擦系数、偏航制动缸弹性模量、摩擦片弹性模量;开双槽的摩擦片对制动稳定性影响显著,开单槽影响较小;制动稳定性受制动压力与偏航速度影响很小;参数优化后的偏航制动器制动不稳定系数降低73.7%。该研究结论可为偏航制动器设计、开发提供理论指导。     

大型风电机组制动系统研究

制动系统在风电机组中起到重要作用,它对风电机组的安全运行有很大影响。本文在传统制动方式的基础上,提出了一种新的制动方法,通过对高速轴与低速轴分别实施制动,可以减少低速轴侧闸瓦面积,而高速轴也不会因力矩太大对齿轮箱造成伤害。     

储能对含高风电渗透率系统暂态稳定性的影响

由于可再生能源并网会带来随机性和波动性,高比例可再生能源并网的暂态特性与传统电力系统有显著区别。因此,研究了在高比例可再生能源并网中加入储能装置对系统暂态稳定性的影响。首先建立了双馈风力发电机的模型和等值的双机群系统节点导纳矩阵,并对送端机组机械功率增量和双馈风机外特性的关系进行了理论推导,在此基础上分析了高比例风电渗透率对风火打捆系统功角稳定性的影响,然后建立储能模型,仿真分析了有无储能装置对风电渗透率的影响。结果表明,加入储能装置后,可使同步机的第一摆角度有效减小,且在风电渗透率增大的同时,更好地维持了系统的暂态稳定性。     

含风电地区电网暂态过程对频率稳定性 影响的动态模拟

摘要： 针对含风电地区电网暂态过程对电力系统频率稳定性的影响问题,分析了含风电地区电网等值模型三相短路暂态过程系统频率响应特性。以蒙西某含风电地区电网为原型,根据相似性原理建立了电力系统动态模拟实验模型,实验结果验证了并网风电规模的大幅增加不利于暂态频率稳定性的结论,表明电力系统动态模拟是研究风电并网频率稳定问题的有效手段。     

通过SVC和TCSC联合改善异步机风电场暂态电压稳定性研究

用静止无功补偿器(SVC)和可控硅控制串联补偿器(TCSC)进行联合补偿,以提高异步风机风电场的暂态电压稳定性。在Matlab/Simulink中搭建了风电场及相关电网模型,通过仿真计算验证了SVC和TCSC对异步机风电场与电网暂态电压稳定性的作用。研究结果表明:在风速随机波动的情况下,SVC能动态地补偿无功功率,保持系统的暂态稳定性;当接入电网发生三相短路的大扰动故障时,TCSC能够有效地恢复机端电压,提高了风电场的低电压穿越能力。     

1.5MW风力机塔架-基础的动力特性研究

采用多种计算模型结合敏感性分析,研究了塔架及塔架-基础的动力特性,发现塔架与基础的振动有一定的耦合作用;考虑基础与塔架相互作用后,塔架各阶自振频率降低,特别是高阶自振频率降低较多;在地震液化等极端工况下,地基基础对塔架动力特性的影响更明显。总结并分析了塔架的振源,指出脉动风荷载是风力机设计中必须重视的部分;风绕塔架流动一般处于超临界或跨临界范围,在超临界范围不会出现明显的塔架涡激振动,在跨临界范围可能出现严重的振动;风轮属细长弹性体、气动特征明显,其振动响应比较复杂且易发生破坏事故。为减小柔性塔架振幅,给出了风力机起动时快速跳过瞬态共振区、增加塔架阻尼和优化塔架体型以进一步改善塔架动力特性等方面的建议。     

Simulation of wind-power impact on the transient fault behaviour of grid-connected wind turbines

This paper deals with the analysis of the possible adoption of a static synchronous compensator (STATCOM) with grid-connected constant-speed wind turbines. Three different cases are simulated using Matlab/Simulink for investigating wind-power impact on a power grid connected to wind turbines. The simulations yield information on (i) how the faults impact on the wind turbines and (ii) how the STATCOM influences the post-fault behaviour of the power system. In this paper, an attempt is made to compare the impact, in terms of voltages and active and reactive powers, of adding wind turbines and STATCOM to an electrical power grid. The simulations show that the goal of keeping turbines operational can be achieved.     

Comparison of simulators for variable‐speed wind turbine transient analysis

This paper presents a comparison of three variable‐speed wind turbine simulators used for a 2 MW wind turbine short‐term transient behaviour study during a symmetrical network disturbance. The simulator with doubly fed induction generator (DFIG) analytical model, the simulator with a finite element method (FEM) DFIG model and the wind turbine simulator with an analytical model of DFIG are compared. The comparison of the simulation results shows the influence of the different modelling approaches on the short‐term transient simulation accuracy. Copyright © 2005 John Wiley & Sons, Ltd.     

Flap/lead–lag aeroelastic stability of wind turbine blades

A numerical tool for investigating the aeroelastic stability of a single wind turbine blade subjected to combined flap/lead–lag motion is presented. Its development is motivated by recent concern about destructive edgewise vibrations of modern stall‐controlled blades. The stability tool employs a finite element formulation to discretize in space the structural and aerodynamic governing equations. Unsteady aerodynamics is considered by means of the extended ONERA lift and drag models. The mathematical form of these models allows for a combined treatment of dynamics and aerodynamics through the introduction of a so‐called ‘aeroelastic beam element’. This is an extended two‐node beam element having both deformation and aerodynamic degrees of freedom. Several linear and non‐linear versions of the stability tool are available, differing in the way that instantaneous lift and/or drag is treated. In the linear case, stability is investigated through eigenvalue analysis. Time domain integration is employed for non‐linear stability analysis. Results are presented and discussed for a 17 m stall‐controlled blade. Copyright © 2001 John Wiley & Sons, Ltd.     

风轮机输出特性模拟系统的设计

为了在不具备风场环境的情况下进行风力发电技术研究,设计了一套风轮机输出特性模拟系统.通过建立随机风速模型和风轮机转矩输出特性计算式,利用变频器控制异步电机的输出转矩来模拟风轮机的输出特性,使用所搭建的实验平台进行试验.试验结果表明,该模拟系统具有良好的动态实时特性,适用于在实验室内进行风力发电技术的研究工作.     

风力机动态模拟方法研究

由于受条件限制,实验室无法进行真实风力机发电的实验,因此利用常用电机模拟风力机,对风力发电及并网进行研究可作为一种实用方法。在分析风力机的机械特性基础上,利用三种电机模拟风力机,并给出相关结论。     

基于Matlab/Simulink的风力机性能仿真研究

随着风力发电技术的发展,变速风力发电技术成为了风力发电发展的趋势。风力机作为变速风力发电机组的重要部分,其性能影响到风力发电机组的整体性能。根据变速风力机的静态性能特点,采用Matlab／Simulink软件对其进行建模,并给变速风力发电机组风力机输入模拟变速风速进行仿真研究,给出了风力机的静态性能数据和仿真波形。结果表明：通过调节影响风力机性能的各因素,保持发电机的转速与主导风速之间特定的最优比例系数,使得风力机保持在最佳叶尖速比下运行,跟随变速风速可实现最大风能捕获;对变速风力机的静态性能研究建模方法是正确可行的。     

Model‐based control addition to prescribe DFIG wind turbine fast frequency response

This paper investigates the physical capability of double‐fed induction generator (DFIG) wind turbines for inertial support of frequency response. Frequency stability is modeled using the DFIG electromechanical and generator controller dynamics, and a destabilizing effect is demonstrated in low‐inertia systems. To improve response, a synchronous reference frame DFIG controller is proposed that acts by following low‐frequency grid dynamics and adds a fast acting proportional plus integral (PI)‐controlled frequency‐responsive component to existing qd current commands. The proposed controller is derived in a straightforward manner using only the DFIG dynamic equations and is designed using pole/zero placement techniques. Laboratory experiments using a micro‐scale DFIG wind turbine with hub‐emulating flywheel prove better capability for transient frequency regulation even under extreme load change. The result is a DFIG controller that balances the appearance of transients in electrical and mechanical systems. Value is achieved in providing immediate continuous inertial response to support load change. The proposed frequency response can improve the use of existing physical inertia from wind turbines.     

Transient and dynamic control of a variable speed wind turbine with synchronous generator

In this article, a controller for dynamic and transient control of a variable speed wind turbine with a full‐scale converter‐connected high‐speed synchronous generator is presented. First, the phenomenon of drive train oscillations in wind turbines with full‐scale converter‐connected generators is discussed. Based on this discussion, a controller is presented that dampens these oscillations without impacting on the power that the wind turbine injects into the grid. Since wind turbines are increasingly demanded to take over power system stabilizing and control tasks, the presented wind turbine design is further enhanced to support the grid in transient grid events. A controller is designed that allows the wind turbine to ride through transient grid faults. Since such faults often cause power system oscillations, another controller is added that enables the turbine to participate in the damping of such oscillations. It is concluded that the controllers presented keep the wind turbine stable under any operating conditions, and that they are capable of adding substantial damping to the power system. Copyright © 2007 John Wiley & Sons, Ltd.