风力发电系统暂态功率控制仿真模型

等值风电机组功率暂态响应参数优化,能够有效提高电力系统暂态过程的稳定性能。传统仿真软件缺少准确的风力发电系统暂态参数及其控制模型,在一定程度上影响了分析大规模风电接入后电网暂态过程响应特性的准确度。文章提出一种计及特定风速条件下风电机组有功和无功输出限制的风电系统功率暂态控制模型。该模型由风电系统有功出力控制、无功出力控制及功率极限优化控制3部分组成。利用ADPSS仿真平台搭建了针对风电系统暂态过程的控制模型,并对风电与火电并网系统进行仿真分析。仿真结果表明,该控制模型能够有效地提高大规模风电接入条件下的电力系统暂态响应特性。     

大规模风电并网对宁夏电网失步振荡的影响

大规模的风电接入会使宁夏电网产生失步振荡。针对此问题,文章利用PSD-BPA建立宁夏"风火打捆"等值单机无穷大系统,从风电接入比例、有无无功补偿以及运行方式3个方面对系统失步振荡特性进行仿真分析,并给出外送断面配置的失步解列装置的响应及动作的情况;然后,结合风电场接入宁夏电网实例,进一步进行仿真验证。结果表明,风电并网容量越多,风电场具备无功补偿时,或在恒电压运行方式下有利于抑制电网失步振荡,提高电网稳定性。     

大规模风电接入电网的稳定性分析

针对大规模风电接入电网将严重影响系统的稳态运行和动态特性的问题,结合风电特性,以潮流分析、暂态稳定为基础并考虑联络线潮流控制,探讨了大规模风电接入对电网运行的影响.以实际电网为例进行仿真计算,分析了风电接入后稳态运行状况的变化和风电并网对系统暂态动态特性的影响,研究了AGC控制在联络线功率控制中的应用.     

大型风电场运行的特点及并网运行的问题

随着国家能源结构的调整,并网运行的风电规模迅速增加,大规模风电集中并网相应安全问题如何评估和解决,是风电发展过程中急需解决的问题。文章分析了大规模风电场集中接入后对电网调频能力、无功电压控制、电能质量等方面的影响,并提出相应的对策建议。     

含大规模风电接入电网的双时间尺度无功协调控制

大规模风电集中并网已经成为中国风电送出的主要模式,通过配置无功补偿装置,使电网无功电压波动问题得到了大幅改善,但电压波动问题在局部地区仍然存在。文章将无功补偿装置分为离散控制和连续控制两类,针对汇集站电压的长周期大幅度波动分量和短周期小幅度波动分量,提出分别应用离散和连续无功补偿装置在小时级和分钟级时间尺度上进行抑制;在此基础上,提出了两类无功补偿装置滚动协调控制策略。通过对我国某大规模风电集中接入电网进行仿真计算,验证了所提控制策略可有效解决电压波动问题,显著提高了含大规模风电接入电网的电压运行水平。     

电力机车负序电流分量对恒速恒频风电机组的影响研究

电力机车作为单相冲击性负荷,在其运行过程中会产生负序分量。当牵引站和风电场集中接入地区电网时,电力机车产生的负序分量会通过电网间接影响到恒速恒频风电机组的安全稳定运行。文章针对目前部分地区牵引站与风电场同时接入电网的情况,从理论上分析了电力机车负序特性及其对风电机组的影响,并通过搭建牵引站与风电场并存地区电网模型,仿真分析不同牵引工况的电力机车对不同运行方式下风电机组的机端电流、瞬时功率等参数的影响,验证理论分析的正确性,最后提出能够减小电力机车负序对风电机组影响的措施。     

机遇与挑战并存的酒泉风电基地

本文分析了酒泉风电基地资源与市场逆向分布、出力时空分布等特点,研究了大规模风电集中并网面临的送出、消纳、调峰、系统稳定和运行控制等方面的挑战,结合大规模风电基地的运行实际,提出了应对措施及规范发展的建议。     

西北电网风电调度运行管理研究

介绍了西北电网的风电场现状、规划容量及接入情况．阐述了大规模风电场接入对西北电网调频、调峰、稳定性及无功调节等各方面安全运行带来的影响,分析研究了大量风电场集中投运对发电计划编制、调度运行控制、电力市场交易模式、并网运行管理所提出的新要求,最后提出了加快750骨干网架建设、提高对风电的监控能力及调度技术支撑手段、探索电量交易模式及消纳机制、加强风电并网运行管理等解决方案和应对策略,确保西北风电与电网实现协调、有序的发展。     

酒泉千万千瓦风电基地集中并网面临的挑战及应对措施

伴随着千万千瓦风电基地的陆续开工建设,中国大规模风电并网存在一系列技术问题,如何应对大规模风电集中并网的挑战,促进风电健康发展,成为国内外广泛关注的焦点。本文以酒泉风电基地为例,分析了大规模风电基地集中并网的特点和运行特性,研究了大规模风电集中并网面临的送出能力、调频调峰、消纳能力和系统稳定等方面的挑战,提出了酒泉风电联合外送的技术路线和大规模风电集群控制系统的应对措施。     

我国风电大规模外送协同运行方式研究

由于风力发电具有随机性、间歇性和不可控性等特点,大规模接入后对电网运行将会产生较大影响,目前风电与电网的适应性和配套问题已成为限制风电发展和使用的瓶颈。基于风电出力特性,结合大规模风电外送时存在的问题,研究分析了风电外送协同运行方式,提出了风电大规模外送协同运行方式结构框架,并结合实例进行了应用分析。结果表明,在送端配置相应配套电源及调整风电并网容量等措施后,可有效解决风电外送电力瞬变、随机间隔等问题,并能促使风电外送电力过程相对平稳,降低风电弃风率、增加输送有效容量、提高输变电利用小时数。     

变流器模块损坏原因分析及对策

变流器作为风机的重要部件,对机组的安伞稳定经济运行有着重要的意义.本文介绍了风变电流器的现状、市场趋势以及SWITCH变流器的特点,并针对风电场全功率变流器实际运行中的主要故障进行了分析,给出了相关的应对措施.     

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.     

Dynamic models of wind farms with fixed speed wind turbines

The increasing wind power penetration on power systems requires the development of adequate wind farms models for representing the dynamic behaviour of wind farms on power systems. The behaviour of a wind farm can be represented by a detailed model including the modelling of all wind turbines and the wind farm electrical network. But this detailed model presents a high order model if a wind farm with high number of wind turbines is modelled and therefore the simulation time is long. The development of equivalent wind farm models enables the model order and the computation time to be reduced when the impact of wind farms on power systems is studied. In this paper, equivalent models of wind farms with fixed speed wind turbines are proposed by aggregating wind turbines into an equivalent wind turbine that operates on an equivalent wind farm electrical network. Two equivalent wind turbines have been developed: one for aggregated wind turbines with similar winds, and another for aggregated wind turbines under any incoming wind, even with different incoming winds.The proposed equivalent models provide high accuracy for representing the dynamic response of wind farm on power system simulations with an important reduction of model order and simulation time compare to that of the complete wind farm modelled by the detailed model.     

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.     

Research on a power quality monitoring technique for individual wind turbines

The extensive deployment of megawatt-scale wind turbines is bringing more challenges to the safety and stability of electric grid than ever before. This is not only because of the unstable wind over time but the increased risk of power quality pollution by defective wind turbines particularly when the turbines today are still experiencing various reliability issues. To prevent the power quality pollution by defective turbines, a new power quality monitoring technique dedicated for individual wind turbines is developed in this paper, so that the quality of the power generated by an individual turbine can be monitored by the wind turbine condition monitoring system. Through simulated and physical experiments on a specially designed test rig, some encouraging results have been achieved. It has been shown that the proposed technique is not only valid for monitoring the power quality of an individual wind turbine, but helpful in detecting the mechanical and electrical faults occurring in the wind turbines.     

Attitudes towards on-land and offshore wind power development in Denmark; choice of development strategy

Wind power generation is expected to increase significantly in the near future. Owing to the increasingly limited possibilities for using on-land turbines, offshore wind generation is a potential alternative. However, wind turbines located offshore are still associated with visual disamenities potentially making offshore location a less attractive alternative to on-land wind power generation. The present paper analyses attitudes towards both on-land and offshore wind power development using a probit model. It also discusses the elicited determinants of attitude in relation to developing wind power on-land or offshore. Compared to other papers on attitude, the paper is unique in the sense that the Danish population has considerable experience with the different impacts associated with wind turbines compared to most of the other countries investing in wind power generation. This is particularly evident with regards to offshore development. The paper establishes that whilst offshore wind farms are preferred to on-land development, the results also imply that on-land development is still a feasible alternative. In that relation, differences in wind power generation costs and the substitution of smaller on-land turbines with fewer but larger turbines might make on-land development even more attractive. On a more detailed level, younger respondents are more positive towards wind power than older respondents. Interestingly, respondents living close to either on-land or offshore wind turbines did not display a more negative attitude towards wind power generation when compared to respondents who were not living close to wind turbines.     

Wind farm—A power source in future power systems

The paper describes modern wind power systems, introduces the issues of large penetration of wind power into power systems, and discusses the possible methods of making wind turbines/farms act as a power source, like conventional power plants in power systems. Firstly, the paper describes modern wind turbines and wind farms, and then introduces the wind power development and wind farms. An optimization platform for designing electrical systems of offshore wind farms is briefed. The major issues related to the grid connection requirements and the operation of wind turbines/farms in power systems are illustrated.     

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.     

Critical analysis of methods for mathematical modelling of wind turbines

Accurate modelling is crucial in designing an optimum system. Wind speed distribution of selected site, hub height and power output curve of chosen wind turbine, are the main factors which influence the performance of wind turbines, and therefore, these must be properly accounted for during modelling of the wind turbines.This paper presents comparative study of various methods for mathematical modelling of wind turbines, with reference to three commercially available wind turbins, with the help of an algorithm developed.It has been found that modelling methods, based on fundamental equations of power available in the wind, are cumbersome to use and do not correctly replicate the behaviour of actual wind turbines.Models based on a presumed shape of power curve, though simple to use, also lack the desired accuracy; however, they give satisfactory response for higher annual average wind speeds.Modelling methods in which actual power curve of a wind turbine is used for developing characteristic equations, by utilising curve fitting techniques of method of least squares and cubic spline interpolation, give accurate results for wind turbines having smooth power curve; whereas, for turbines having not so smooth power curve, model based on method of least squares is best suited.     

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.