风电机组低电压穿越能力影响因素分析与实例

我国风电大规模汇集地区多处于电网末端,电压波动性强,随着对风电并网安全的关注和风电机组并网性能要求的提高,低电压穿越能力已成为衡量风电机组并网性能的重要指标。文章调研了同一区域内多个风电场实际运行中的低电压穿越故障情况,分析了整机制造厂家、高校及相关研究机构对风电机组低电压穿越技术的研究现状。通过分类统计测试过程中遇到的风电机组低电压脱网故障和总结56台风电机组的低电压穿越测试结果,分析了造成风电机组低电压穿越能力不足的原因,并对引起风电机组低电压穿越能力不足的影响因素进行了阐述。目前,软件版本控制、保护定值的设置与管理、硬件的维护水平已经成为并网风电机组低电压穿越能力的主要影响因素。     

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SIMULINK的失速型风电机组软并网控制系统的仿真分析

软并网控制技术是失速型风电机组电控系统的关键技术之一。该文分析了利用晶闸管进行软并网的原理，建立了机组并网的SIMULINK仿真模型，在对仿真模型进行验证的基础上，对各种并网过程进行了仿真，提出了机组并网转速与晶闸管移相触发规律应随电机转子加速度凋节的控制策略，为失速型风电机组软并网系统的研制提供了必要的参考依据。     

基于变距系统的风电机组并网运行特性的研究

依据风电机组的变桨距控制原理和风电机组的运行特性,建立了转速环和功率环控制的风电机组变桨距控制系统,结合双馈风电机组各部分数学模型,在PSCAD/EMTDC中搭建了风电机组的并网仿真模型。对不同风速段湍流风况条件下的风电机组并网运行特性进行仿真,实现了不同运行阶段下风电机组运行特性的优化控制,并在此基础上分别仿真了阵风干扰和电网故障扰动下风电机组的动态运行特性。仿真结果分析表明,双环变桨距控制系统可以较好地优化风电机组的功率输出特性,在电网发生故障时桨距角的快速动作也可以有效地抑制故障暂态响应的进一步恶化,有利于电网的迅速恢复。     

风电机组低电压穿越能力测试中的风机故障

近年来,我国风力发电装机容量不断增长,大规模风电并网对电网的影响日益受到重视。低电压穿越能力是风电机组并网特性的重要考核指标之一,该文详细分析了目前风电机组低电压穿越能力测试所依据的标准,就标准中对风电场及风电机组低电压穿越性能的具体要求进行了分项阐述,在此基础上总结了已开展的现场低电压穿越测试中风机发生的种种故障及其原因,证明了同样机型的风电机组测试性能存在差异,而且现场试验证实了风机零部件故障也成为影响风机低电压穿越性能重要因素。     

基于串联动态制动电阻的异步风电机组暂态稳定性研究

以并网笼型异步风电机组为例,分析了利用串联动态制动电阻提高并网异步风电机组在电网故障下暂态稳定性的作用机理以及效果.建立了并网异步风电机组的数学模型,基于Matlab/Simulink仿真平台,对比分析了采用串联动态制动电阻、并联动态制动电阻以及无功补偿装置的作用效果.仿真结果表明,采用串联动态制动电阻可以有效改善并网异步风力发电机组的暂态稳定性;同时,采用串联动态制动电阻和无功补偿装置,可显著提高机组的暂态稳定性,减少对无功补偿的需求,降低风电场的运行成本.     

回望我国第一座陆上风电场

<正>在改革开放初期,我国尚未掌握风电场的建设经验和风电并网技术,也缺少适用的并网型风电机组。为了通过风电场建设来更好地开发利用风能,推动我国并网型风电机组的产业化发展,1983～1985年,山东省政府和航空工业部组织了相关学科的专家学者,对国际、国内风能的发展和利用状况进行了广泛、深入的考察和论证。在认真分析的基础上,提出了"引进机组、学习     

火电机组灵活性改造与输电网规划多阶段联合决策方法

大规模风电并网对电力系统灵活性提出了很高的要求.针对大规模风电并网背景下的消纳问题提出了一种火电机组灵活性改造与输电网规划多阶段联合决策方法.通过将火电机组灵活性改造纳入输电网规划优化决策,统筹优化系统灵活性及传输能力,促进大规模风电并网消纳.基于规划周期内负荷功率预测曲线,并计及风电时序出力不确定性情景,以输电网建设...     

“2011首届中国储能产业发展峰会”将召开

酒泉风电基地598台风电机组脱网事故再度凸显风电并网瓶颈,多个风电基地风电并网难问题也时时见诸报端。在经历了前两年的风电装机爆发式增长后,我国风电并网瓶颈日益凸显,已成为今日不可解而必须解决之难题。而业界已经取得的共识是:储能正是从根本     

风特性对风力发电机组输出功率的影响

为了准确研究不同类型的风速对并网风电机组输出功率的影响,建立了并网风力发电机模型和不同类型风速的模型。在不同类型风速的扰动下,对异步风电机输出功率的波动进行了仿真分析;针对引起功率振荡最严重的阵风,进行了不同频率的阵风扰动下风电机组功率振荡的比较,对阵风扰动下风电机组间的相互影响进行了仿真分析。结果表明,在相同幅值的扰动下,阵风引起的风电机组功率振荡最严重,机组功率振荡情况与阵风扰动的频率有关,单台机组在阵风扰动下产生的振荡对其他机组也会产生一定的影响。     

失速型风电机组软并网控制新算法

在介绍软并网控制系统的基础上,针对失速型风电机组的特点提出了一种简单、可靠的数字触发新算法--双余算法.该算法计算简便,具有较快的响应时间、良好的适应性和抗干扰能力,占用系统资源少,便于现场调试.以此算法为基础设计的软并网控制系统,应用在新疆达坂城风电场F3号等机组上,收到了非常满意的效果.该软系统对提高风力发电机运行的可靠性和并网成功率,减轻风力发电机并网冲击电流有很大的作用.     

Flicker contribution from wind turbine installations

In this paper, the flicker emission from a wind park connected to a grid with a high wind energy penetration is evaluated. The influence of wind speed, turbulence intensity, grid voltage quality, grid types, and number of turbines operating in the same group is measured and analyzed. The investigated wind turbines are of constant-speed stall-regulated type. It is found that the voltage quality of the grid to which the turbines are connected strongly influences the flicker emission of the turbines. Moreover, it is found that the formula used in IEC-61400-21 for determining the flicker contribution from a whole wind park gives too low total flicker value.     

Impact of fault ride‐through requirements on fixed‐speed wind turbine structural loads

The emphasis in this article is on the impact of fault ride‐through requirements on wind turbines structural loads. Nowadays, this aspect is a matter of high priority as wind turbines are required more and more to act as active components in the grid, i.e. to support the grid even during grid faults. This article proposes a computer approach for the quantification of the wind turbines structural loads caused by the fault ride‐through grid requirements. This approach, exemplified for the case of a 2MW active stall wind turbine, relies on the combination of knowledge from complimentary simulation tools, which have expertise in different specialized wind turbines design areas. Two complimentary simulation tools are considered i.e. the detailed power system simulation tool PowerFactory from DIgSILENT and the advanced aeroelastic computer code HAWC2, in order to assess of the dynamic response of wind turbines to grid faults. These two tools are coupled sequently in an offline approach, in order to achieve a thorough insight both into the structural as well as the electrical wind turbine response during grid faults. The impact of grid requirements on wind turbines structural loads is quantified by performing a rainflow and a statistical analysis for fatigue and ultimate structural loads, respectively. Two cases are compared i.e. one where the turbine is immediately disconnected from the grid when a grid fault occurs and one where the turbine is equipped with a fault ride‐through controller and therefore it is able to remain connected to the grid during the grid fault. Copyright copy; 2010 John Wiley & Sons, Ltd.     

Dynamic modelling and control of fully rated converter wind turbines

Today, many countries are integrating large amount of wind energy into the grid and many more are expected to follow. The expected increase of wind energy integration is therefore a concern particularly to transmission grid operators. Based on the past experience, some of the relevant concerns when connecting significant amount of wind energy into the existing grid are: fault ride through requirement to keep wind turbines on the grid during faults and wind turbines have to provide ancillary services like voltage and frequency control with particular regard to island operation.While there are still a number of wind turbines based on fixed speed induction generators (FSIG) currently running, majority of wind turbines that are planned to be erected are of variable speed configurations. The reason for this is that FSIG are not capable of addressing the concern mentioned above. Thus, existing researches in wind turbines are now widely directed into variable speed configurations. This is because apart from optimum energy capture and reduction of mechanical stress, preference of these types is also due to the fact that it can support the network such as its reactive power and frequency regulation. Variable wind turbines are doubly fed induction generator wind turbines and full converters wind turbines which are based on synchronous or induction generators.This paper describes the steady state and dynamic models and control strategies of wind turbine generators. The dynamic models are presented in the dq frame of reference. Different control strategies in the generator side converter and in the grid side converter for fault ride through requirement and active power/frequency and reactive/voltage control are presented for variable speed wind turbines.     

Fault ride-through capability of DFIG wind turbines

This paper concentrates on the fault ride-through capability of doubly fed induction generator (DFIG) wind turbines. The main attention in the paper is, therefore, drawn to the control of the DFIG wind turbine and of its power converter and to the ability to protect itself without disconnection during grid faults. The paper provides also an overview on the interaction between variable-speed DFIG wind turbines and the power system subjected to disturbances, such as short circuit faults. The dynamic model of DFIG wind turbine includes models for both mechanical components as well as for all electrical components, controllers and for the protection device of DFIG necessary during grid faults. The viewpoint of the paper is to carry out different simulations to provide insight and understanding of the grid fault impact on both DFIG wind turbines and on the power system itself. The dynamic behaviour of DFIG wind turbines during grid faults is simulated and assessed by using a transmission power system generic model developed and delivered by the Danish Transmission System Operator Energinet.dk in the power system simulation toolbox PowerFactory DIgSILENT. The data for the wind turbines are not linked to a specific manufacturer, but are representative for the turbine and generator type used in variable-speed DFIG wind turbines with pitch control.     

Modelling and control of variable speed wind turbines for power system studies

Modern wind turbines are predominantly variable speed wind turbines with power electronic interface. Emphasis in this paper is therefore on the modelling and control issues of these wind turbine concepts and especially on their impact on the power system. The models and control are developed and implemented in the power system simulation tool DIgSILENT. Important issues like the fault ride‐through and grid support capabilities of these wind turbine concepts are addressed. The paper reveals that advanced control of variable speed wind turbines can improve power system stability. Finally, it will be shown in the paper that wind parks consisting of variable speed wind turbines can help nearby connected fixed speed wind turbines to ride‐through grid faults. Copyright © 2009 John Wiley & Sons, Ltd.     

风电场的稳定问题

介绍了大型风电场的并网技术;指出了依据风电场的容量大小,其接入电网的电压等级也有所不同;在对风电系统的稳定性进行定位的基础上,通过对国内外包含风电场的电力系统的研究成果的对比分析,展现了不同类型的风电机组在电力系统暂态过程中的行为特性,为从事风电研究的科技工作者提供参考.     

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.     

Effects of the model selected for the power curve on the site effectiveness and the capacity factor of a pitch regulated wind turbine

The present work is based on the fact that site effectiveness is a relevant value when analysing the suitability of a location for constant-speed wind turbines. An analytical expression is developed to calculate the said effectiveness by means of a potential adjustment model to the ascending segment of the power curve in pitch regulated wind turbines. Upon analysis of the results obtained for maximum effectiveness in a given location, using both the potential model and the quadratic model applied in earlier studies, no significant differences were observed in wind conditions of interest for wind energy applications. Notwithstanding, when the cut-in wind speed was compared, corresponding to the maximum effectiveness values at the same location according to the two models indicated, noticeable differences were observed. It can therefore be deduced that, when selecting this design parameter, a careful study should be made in order to determine which model best fits the power curve of the wind turbine under analysis for a specific location.     

Viability and economic analysis of wind energy resource for power generation in Johannesburg,South Africa

In this study, wind characteristics and wind power potential of Johannesburg are investigated using 5-min average time series wind speed collected between 2005 and 2009 at anemometer height of 10 m. The statistical distribution that best fits the empirical wind speed data at the site of study is first determined based on the coefficient of determination and root mean square error criteria. The statistical parameters and wind power density based on this model are estimated for different months of the year using standard deviation method. Economic analyses of some wind turbines are also carried out. Some of the key results show that the site is only suitable for small wind turbines in a standalone application. A 10 kW wind turbine with cut-in wind speed of 3.5 m/s, rated wind speed of 9 m/s, and cut-out wind speed of 25 m/s seems most appropriate in Johannesburg with the lowest cost that varies from 0.25 to 0.33 $/kWh.