含不同风电机组的风电电网仿真研究

为了研究包含恒速异步风力发电机和双馈异步风力发电机的风电场对电网的影响,应用Matlab 7.0建立了含不同风电机组的风电场动态模型。分析了风电场对电网暂态稳定性的影响,风电机组电压恢复情况,有功、无功变化情况,以及不同风电机组的低电压穿越能力。仿真结果表明：双馈异步风力发电机变速平稳、低电压穿越能力较强,有利于优化电能质量;当电网发生故障时,应针对不同的风电机组采取不同的控制策略以提高电力系统稳定性。     

Fixed-speed wind-generator and wind-park modeling for transient stability studies

Increasing levels of wind-turbine generation in modern power systems is initiating a need for accurate wind-generation transient stability models. Because many wind generators are often grouped together in wind parks, equivalence modeling of several wind generators is especially critical. In this paper, a reduced-order dynamic fixed-speed wind-generator model appropriate for transient stability simulation is presented. The model is derived using a model reduction technique of a high-order finite-element model. Then, an equivalencing approach is presented that demonstrates how several wind generators in a wind park can be combined into a single reduced-order model. Simulation cases are presented to demonstrate several unique properties of a power system containing wind generators. The results in this paper focus on horizontal-axis turbines using an induction machine directly connected to the grid as the generator.     

Impact of Wind Integration on Transient Voltage Stability in Regional Grid

With the increasing development of wind power,the scale of wind farms and unit capacity of wind turbines are getting larger and larger,and the impact of wind integration on power systems cannot be igno...     

Performance and efficiency control enhancement of wind power generation system based on DFIG using three-level sparse matrix converter

Nowadays, the power generation systems based on wind turbines is increasing continuously in the world. Hence, there are intense efforts provided by researchers for the development of this area. In high power system applications, multilevel converters are a competitive alternative to the two-level inverters. In this paper, a three-level sparse matrix converter (SMC3l) associated to a grid connected variable speed wind generation (VSWG) scheme using a doubly fed induction generators (DFIGs) is investigated. Therefore, the dynamic behavior of a wind generator, including models of the wind turbine, DFIG, SMC3l control algorithm and power control is studied. Simulation results of the dynamic models of the wind generator are presented, for different operating modes sub-synchronous, synchronous and hyper-synchronous, to show the good performance and the efficiency control enhancement of the VSWG system using the proposed SMC3l.     

双馈风力发电机组系统接入与稳定运行仿真

分析了包含大量异步风力发电机组的风电场并网运行后对电力系统静态和动态稳定性的影响。从系统接入和稳定运行的角度研究了双馈风力发电机组及普遍采用的定子磁链定向矢量控制策略在提高风电系统稳定性方面的优势与不足。以实际机组为例在PSCAD/EMTDC平台上建立了仿真模型,结果表明双馈风力发电机组在风速发生变化时不仅能够以变速恒频方式运行并追踪最大风能,且电网电压也比传统鼠笼式风力发电机组更为稳定。在系统发生最严重的三相接地故障时,风电场具有更好的暂态稳定性。     

不同风电机组对电网暂态稳定性的影响

为了研究由恒速异步风力发电机、双馈异步风力发电机和直驱永磁同步风力发电机组成的风电场对电网的影响,利用DIgSILENT/Powerfactory建立了风电场的动态模型,通过仿真分析比较了上述3种风电场对电网暂态稳定性的影响,以及风电场出口电压恢复情况和风电场的无功变化等,得结论：恒速异步风力发电机的稳定性较差,双馈异步风力发电机和直驱式交流永磁同步风力发电机能够提高电网发生故障后同步发电机的短期电压稳定性,减小系统所需的无功储备,有利于电网的电压稳定。     

双馈风机的动态稳定分析

本文探讨了双馈型风电场并网后对地区电网动态稳定性的影响。建立了风电机组的空气动力学模型、轴系模型及桨距角控制系统模型;并在此基础上推导了风电场接入后的地区电网动态稳定特征值分析的状态矩阵。对风电机组接入的广西电网动态稳定性的影响进行全面的仿真分析,仿真证明,通过调整风电场的接入位置,以及采用变速风电机组的稳定控制模型,这两种方式能够有效改善系统阻尼,增强系统动态稳定性。     

SVC与桨距角控制改善异步机风电场暂态电压稳定性

研究了改善异步机风电场暂态电压稳定性的措施。基于普通异步机的恒速风电机组是目前世界上应用最为广泛的风电机组之一,由于其发出有功功率的同时吸收无功功率,会导致接入风电地区电网的电压稳定性降低。文中在DIgSILENT/PowerFactory中建立了静止无功补偿器（SVC）控制模型及风电机组桨距角控制模型,通过包含风电场的电力系统仿真计算验证了模型的有效性及其对异步机风电场与电网暂态电压稳定性的贡献。研究结果表明,在接入风电地区电网发生三相短路的大扰动故障时,SVC能够有效地帮助恒速风电机组在故障后恢复电压,提高输出的电磁功率,桨距角控制能够有效地降低恒速风电机组的输入机械功率,以上2种措施能够避免风电机组机械与电磁功率不平衡引起的异步发电机超速及电压失稳;采用SVC及风电机组桨距角控制能够改善异步机风电场的暂态电压稳定性,确保风电机组连续运行及电网安全稳定。     

风电机组对电力系统暂态稳定性影响分析

风电机组作为环境友好型发电的最大来源在电网中的规模日益扩大,必将影响电力系统的稳定性。文章首先对比了恒速异步(CSWT),双馈变速(DFIG)及直驱同步(DDSG)等市场上广为应用的三种风电机组的结构,分析了各个机组的降阶数学模型;通过一款基于Matlab的电力系统分析工具箱PSAT研究了不同故障持续时间下的风电机组暂态稳定性和系统暂态稳定性,对三种机组及其系统的暂态稳定性进行了分析对比;最后讨论了风力发电机组参数对机组暂态稳定性的影响,得知,发电机参数Rr的增加和Xr、Xs的减小有利于恒速风电机组暂态稳定性的提高,Xm、Rs对机组暂态稳定性影响不明显。     

提高双馈风电机组动态无功协调控制能力的实验研究

随着风电场规模不断增加,风电机组并网对电网的影响逐渐增大,故充分挖掘风电机组的无功电压调节能力和提高机组的无功响应速度对增强电力系统的电压稳定性具有重要作用。定量分析了蒙西电网某风电场单台双馈感应风力发电机(Doubly Fed Induction Generator, DFIG)的无功电压调节能力及限制因素,根据其单台机组的无功调节机理制定动态无功补偿协调控制策略。若系统无功需求超过DFIG无功出力极限时,在保证机组最大发电效益的基础上,提出基于无功差值的双馈感应风力发电机组有功附加控制。并且通过改进的遗传控制算法辨识得到附加控制器参数,该控制在降低机组最小出力的同时确保提高机组无功出力极限,进而满足系统无功需求。最后通过实验验证了所提出的双馈风电机组动态无功协调控制的可行性和准确性,增强了机组的电压稳定能力。     

大型风电场对电力系统暂态稳定性的影响

对大型风电场接入后的电力系统暂态稳定性进行了研究.从理论上分析了基于双馈感应电机的风电机组的暂态稳定机理;基于双馈风电机组的动态数学模型,通过仿真计算研究了大型风电场并网对电力系统暂态稳定性的影响,分析比较了在同一接入点接入双馈风电机组与接入同步发电机组对电力系统稳定性的影响,仿真计算进一步验证了理论分析的结果;最后得出结论:基于双馈风电机组的风电场对电力系统暂态稳定性的影响要好于在同一接入点接入相同容量的同步发电机组.     

Coordinated voltage control of wind-penetrated power systems via state feedback control

This paper presents an optimal coordinated voltage control scheme for preserving long-term voltage stability of power systems. Linear quadratic integral (LQI) controller is employed to construct this scheme. Also, this paper considers the detailed dynamic model of doubly-fed induction generator (DFIG) wind turbine, synchronous generators, over excitation limiter (OEL) and under-load tap changer (ULTC) system, which are important elements influencing voltage stability of power systems. The proposed approach at each time instance involves following two major steps: First, the power system nonlinear equations are linearized and optimal controllers are obtained by LQI technique. Then, in the second step the system dynamic behavior is investigated via time-domain simulations by applying the attained optimal control signals at the first step. The impact of the proposed coordinated voltage control scheme is evaluated by time domain simulations on a well-known test system, under variable wind speed and fault conditions.     

Modelling and performance of fixed-speed induction generators in power system oscillation stability studies

This paper describes the modelling and performance effects of induction generator-based wind farms on the oscillation stability of power systems. For groups of 5, 10 and 20 induction generators, it is established that the basic dynamic properties of each group of generators are similar to those of a third-order equivalent machine model whether the generators are evenly loaded or unevenly loaded. The paper analyses the impact of induction-based wind generation on oscillation stability for multi-machine systems as applied to the standard IEEE 30 bus system. The effects of load model representation, system loading, generator output and transmission line network parameters are considered. In general, the multi-machine system is shown to be well damped under all normal operating conditions.     

基于Crowbar电路的双馈感应风力发电系统低电压穿越的仿真分析

在分析变速恒频双馈风力发电机组和Crowbar电路工作原理的基础上,建立双馈风力发电系统低电压穿越(LVRT)控制模型和Crowbar控制策略。在PSCAD/EMTDC仿真软件中搭建了双馈感应发电机(DFIG)系统模型和LVRT控制模型。针对电网三相对称短路故障下Crowbar的投切策略进行了仿真研究。仿真结果验证,所提策略能实现双馈风力发电机的低电压穿越。     

湍流对风力发电机输出功率影响的研究

针对风电场中湍流对风能捕获和风力发电的影响,依据“湍流圆”模型、空气动力学模型与经典的湍流强度表达式,反向推导因湍流影响而导致风能捕获的损失.以双馈式感应发电机为例,对其并网功率输出与理论风机功率输出进行比较,分析湍流时风机功率输出曲线变化;利用风电场的实际湍流强度值,通过Fluent软件仿真风机运行情况,证明在湍流影...     

Stability and nonlinear controller analysis of wind energy conversion system with random wind speed

In the recent years, globally wind energy has played a vital role in renewable sources in order to minimize the environmental consequence on power generation, As a result of this, computer models of wind turbines for power system stability studies have been developed and supplied to the consumer. Therefore, the development of such models is of particular consequence for stability of power system, which has been studied and can be structured and integrated into network simulation software are needed. However, in this contribution a nonlinear control design modeling is required to stabilize and analyze wind energy conversion system (WECS) by regulating the electrical frequency and stator voltage amplitude of the squirrel-cage induction generator (SCIG) at random wind speed approach is presented. A design scheme consists of dynamic wind turbine system and 3-phase SCIG unit. In this research study, we employ a unique technique based on feedback linearization technique through field oriented control concepts. The controllers were designed in simulated software Matlab in order to regulate the SCIG constraints. The validation of the developing system models will be appropriate to provide for large system stability and control.     

电压源换相高压直流输电改善异步发电机风电场暂态电压稳定性的研究

基于普通异步发电机的恒速风电机组并网风电场会引起本地电网的电压稳定性问题.为此本文分析了并网风电场的电压稳定问题和电压源换相高压直流输电(VSC-HVDC)的风电场并网方式的技术特点,研究了VSC-HVDC的数学模型和控制方式.基于国际大电网会议(CIGRE)B4-39工作组标准模型,应用PSCAD/EMTDC仿真软件建立了大规模风电场并网系统模型,研究了VSC- HVDC输电改善异步发电机风电场暂态电压稳定性的贡献.研究表明VSC-HVDC不仅能够有效实现恒速风电机组在电网发生大扰动故障后的快速电压恢复能力,而且可以避免在电压恢复过程中由风电机组输入输出功率不平衡引起的发电机超速及电压失稳,确保风电机组的连续运行及电网的安全稳定.     

Transient stability simulation of wind generator expressed by two‐mass model

Recently, wind power generation is increasing worldwide. In wind power stations, induction machines are mostly used as generators. Since induction generators have a stability problem similar to the transient stability of synchronous machines, it is important to analyze the transient stability of power systems including wind generators. Although there have been some reports analyzing the transient stability problem, wind turbine and wind generator are, in most cases, modeled as a one‐mass shaft system having total inertia constant. This paper presents simulation analyses of transient stability of power system including induction generator which is expressed by a two‐mass shaft model and analyzes an effect of shaft system modeling on the transient stability characteristics. Simulations are performed by PSCAD/EMTDC in this study. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 162(3): 27–37, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20394     

大容量风电场接入后电网电压稳定性的计算分析与控制策略

由于风电场容量较大,并位于电网末端,可能会对电网的电压稳定性产生较大的影响。为保证风电场投入后的安全,按大干扰下风功率的转换特性及异步发电机的运行特性建立了风电场与相关电网的数学模型,计算了风电场与相关电网发生短路故障后的电压稳定性。通过数值仿真计算,揭示了风电场接入导致电网电压稳定性被破坏的机理,指出机组转速是影响风力机和异步发电机这两个能量转换器工作特性的关键参数,控制风电场内风机的速度增量是保持大容量风电场接入后电压稳定性的关键,靠近故障点的风电单元容量、故障点位置和故障持续时间是影响短路后电压稳定性的主要因素,并提出了大容量风电场接入后保证电网电压稳定性的策略与措施。     

变速恒频双馈异步风力发电系统低电压穿越技术综述

随着以变速恒频(VSCF)双馈异步发电机(DFIG)为主体的大型风力发电机组在电网中所占比例的快速提高,电力系统对并网风力发电机在外部电网故障、特别是电网电压骤降故障下的不问断运行能力提出了更高的要求.本文首先分析了电网电压骤降对DFIG运行的影响,提出了DFIG风力发电系统低电压穿越运行的控制目标,继而总结、评价了各种适合于DFIG风力发电系统的低电压穿越技术,最后指出了DFIG风电系统低电压穿越技术的优化方向,以期展示该技术的最新进展及发展趋势.