毕业设计（论文）外文翻译-风电对电力系统角稳定性的影响.doc

毕业设计(论文)外文资料翻译学 院：机械工程学院 专 业：机械设计制造及其自动化 姓 名： 学 号： 0802070404 (用外文写)外文出处： Impact of Wind Power on the Angular Stability of a Power System 附 件： 1.外文资料翻译译文；2.外文原文。指导教师评语： 签名： 年 月 日附件1：外文资料翻译译文风电对电力系统角稳定性的影响摘要风能转换系统是非常不同的性质与传统发电机组。因此，动态研究必须加以解决，以便将风力为动力系统。角稳定评估风力发电机是一个主要问题在电力系统安全运行。角稳定的风力发电机是由其相应的临界清除时间（建）。在本文中，风力的作用对故障暂态行为调查取代产生2种类型的风力发电机，风力逐渐增加的速度渗透和改变位置的风力资源。仿真分析是建立在14总线测试系统的软件/，这使获得一个广泛的网格组件，以及相关的风力机模型。关键词：角稳定性，横向，风机，风渗透。引言电力网络是一个复杂的系统，这是容易受到干扰。瞬态短路故障是一个非常常见的干扰功率系统。它会在转子附近产生故障，导致这些机器的转速和功率在网络中振荡。当短路清除断开故障，发电机，加速将减速，回到同步与其他系统。如果他们不这样做，并使系统变得不稳定，有可能广泛停电和造成机械性损坏发电机。因此，临界清除时间是最大的时间间隔，故障必须清除，以维护系统的稳定性。毫无疑问的是，风力将发挥主导作用，增加国家电网的清洁无污染能源。然而，随着越来越多的风力发电机连接到电网，其影响的电能质量服务人类与生产是越来越明显，所以重要的是分析电力系统的暂态稳定性，包括风力发电站。三相故障应用到14个总线测试系统，通过断开和清除影响线。本文的重点是：以确定临界清除时间（横向）的若干情况下观察运输行为仿真测试系统在电网故障期间使用的电力系统分析工具箱（部分）。本文的结构如下。首先，风模型描述也；风机的概念描述。然后，测试系统和应用模型的提出。振荡的一组发电机故障暂态行为分析观察下列情况：风模型：风能转化为机械能，通过一个风力涡轮的旋转传递给发电机采用机械传动装置。风力方程给出：Pt=1/8d2v3 Cp其中是空气的密度，d是涡轮半径，是风速，Cp是风力机将风能转换为机械能的效率，称风能利用系数，它与风速，叶片转速，叶片直径和桨叶节距角均有关系，是叶尖速比和桨叶节距角的函数。叶尖速比是叶尖速度除以风速。有许多不同类型的风力涡轮机在世界各地使用，各有其自己的名单的好处和缺点。本文主要类型的风力涡轮机是：恒速风机（图1），其中包括一个网格耦合感应发电机短路9 。风涡轮转子连接到发电机通过变速箱。功率提取风是有限的，在高风速时使用失速效应。没有主动控制系统的使用。可变速度风力涡轮机与绕线转子异步发电机（图1 b）双馈感应发电机（双）。转子绕组供给采用背对背电压源变换器 10。在第一种情况下，风机转子耦合到电机通过变速箱。在高风速功率提取风是有限的俯仰转子叶片。图1a鼠笼型异步发电机。图1b双馈感应发电机测试系统测试系统研究是在图2，它是从测试系统；该网络由14路总线，5台发电机，11和83分支。发电机变压器连接到网格是相应的调整。风力涡轮机的2兆瓦的机器上面介绍的2节。请注意，发电机并不代表一个单一的机器，而是一组强烈耦合发电机，该测试系统总功率分为：表1。有源电力的发电机试验系统发电机N12345功率（MW）65060602525干扰调查是一个三相短路对2号总线。这是最严重的干扰三相故障暂态稳定问题。结果与讨：以假设的影响，风力角稳定的电力系统，包括一三阶段对称故障然后计算横向对应一个没有风等情况下，风源连接到测试系统的不同总线。图2。图2。基本线路没有风的来源基本情况是正常的操作系统没有任何风电连接到系统。故障临界清除时间（建）才能确定使用瞬态模拟 3。对于这种情况，其结果是横向=196毫秒。图3a显示转速发电机故障清除时间比较接近临界清除时间。图3b中的故障，介绍了时间=197毫秒，所以时间超过稳定极限曲线。图3a所有发电机的转子转速=196毫秒图3b所有发电机的转子转速=197毫秒在风源之后，一个风力发电机是连接到系统通过传输线路上评价其效果的角稳定。表2。从模拟结果为角稳定在不同的地点总线总线1总线3总线8总线14CCT（ms）186187283220相比以前的情况下，任何风源连接，整合风源增加了运输稳定时，它是连接在总线8或1总线4，但是相反的情况下1和3总线总线，所以没有一般的陈述可能，如果风力发电提高暂态稳定的利润或如果是相当消极的影响。答案取决于风能资源和问题进行分析，为每个单独的情况。影响类型的发电机技术为了确定影响类型的发电技术，运输行为的网格，2型发电机的研究与保持相同的故障和同一地点的风能。案例1：固定速度故障临界清除时间（建）才能确定使用瞬态模拟。对于这种情况，那里的风源连接到总线3结果是横向=187毫秒。图4显示所有发电机转子故障清除时间比较接近临界清除时间。图4a所有发电机的转子转速=187毫秒图4b所有发电机的转子转速=188毫秒案例2：变速（双馈技术）固定发电机添加到总线3现在是断开和取代的双馈感应发电机（双馈）具有相同的功率（两兆瓦）。因此，变化的技术可以考虑和分析。分析了横向的结果增加稳定极限的情况相比，1只固定转速发电机服务。时间增加横向=216毫秒，如图5所示。这意味着，在暂态网络稳定性增强时，双馈发电机连接而固定测速发电机。图5a所有发电机的转子转速=216毫秒 图5b所有发电机的转子转速=217毫秒比较分析这方面的更详细，表3显示值为双馈发电机技术（变速）和异步发电机（固定变量）的不同位置上。表3。建2种汽轮机技术的几个公共总线。总线N13814横向固定速度（ms）186187220223横向变速（ms）286216300227根据研究结果，这是很清楚的，双馈发电机增加临界清除时间，因此这类发生器提出了最佳性能比鼠笼式异步发电机的功角稳定的网格连接风力，显而易见的是，风力发电，双馈式提供了更好的性能稳定故障消除后，由于角其有能力控制无功功率。风的影响渗透在本节中，风力的作用振荡的研究逐渐增加的速度源风渗透同时观察运输系统行为 11。表4。横向速度不同的风电穿透风资源穿透率（%）3.186.714.0121.65 22 风电总装机功率（MW）24.9652.59109.90169.95172CCT（ms）271229151970从结果，它的结论是，影响风电对电力系统振荡取决于速度的风电穿透，它已被证明，高一级的风力渗透在我们的案例研究是必须低于22%的总电网，否则测试系统失稳。结论本文主要集中在评估的角稳定的确定一个临界清除时间（建），这是观察的行为，发电机的测试系统包括一三个阶段的变化时，几个参数故障。根据先前的模拟，得出以下结论：一般是没有声明，如果风力发电提高暂态稳定的利润或是相当消极的影响。答案取决于风能资源和问题进行分析，为每个单独的情况。影响类型的发电技术在运输的稳定性是非常重要的和双馈发电机提供了更多的表现比鼠笼式异步发电机。已经证明，高一级的风电穿透破坏电力系统时，很大一部分的同步发电能力，取而代之的是风力。最后，很重要的一个计算一个临界清除时间（建）在所有以前的模拟进行了几次这是浪费时间和精力，数值计算方法（横向）是非常需要这种运输的稳定性研究。References 1. Sun T., Chen Z., Blaabjerg F., Voltage recovery of grid-connected wind turbines after a short-circuit fault, Annual Conference of the IEEE Industrial Electronics Society, Virginia, USA, 2003. 2. Saffet Ayasun, Yiqiao Liang, Chika O. Nwankpa, A sensitivity approach for computation of the probability density function of critical clearing time and probability of stability in power system transient stability analysis, Applied Mathematics and Computation, 2006, p. 563. 3. Salman S. K., Teo A. L. I., Investigation into the Estimation of the Critical Clearing Time of a Grid Connected Wind Power Based Embedded Generator, Proceedings of the IEEE/PES transmission and distribution Conference and exhibition 2002, Asia Pacific Pucific, Vol. 11, 2002, p. 975-980. 4. Jauch C., Srensen P., Norheim I., Rasmussen C. Simulation of the Impact of Wind Power on the Transient Fault Behavior of the Nordic Power System, Electric Power Systems Research, VOL: article in press, available online 24 March, 2006, p. 135-144. 5. Federico Milano, Power System Analysis Toolbox Documentation for PSAT version 2.0.0 1, July 9, 2006. 6. Soerensen P., Hansen A.D., Pedro Andre Carvalho Rosas, Wind Models for Prediction of Power Fluctuations of Wind Farms, J. Wind Eng. Ind. Aerodyn, 2002, 90, p. 1381-1402. 7. Tang Hong, WuJunling, Zhou Shuangxi, Modeling and Simulation for Small Signal Stability Analysis of Power System Containing Wind Farm, J. Power System Technology, 2004, 28(1), 38-41. 8. Hansen A.D., Srensen P., Iov F., Blaabjerg F., Initialisation of Grid-Connected Wind Turbine Models in Power-System Simulations, Wind Engineering, 2003, 27(1), p. 21-38. 9. Nandigam K., Chowdhury B. H., Power flow and stability models for induction generators used in wind turbines, IEEE Power Engineering Society General Meeting, 2004, 2, p. 2012-2016. 10. Hansen A. D., Michalke G., Fault ride-through capability of DFIG wind turbines, Renewable Energy, 2007, 32, p. 1594-1610. 11. Ha L. T., Saha T. K., Investigation of Power Loss and Voltage Stability Limits for Large Wind Farm Connections to a Sub-transmission Network, Power Engineering Society General Meeting, 2004, 2, p. 2251-2256. 附件2：外文原文（复印件） Impact of Wind Power on the Angular Stability of a Power System Djemai NAIMI1, Tarek BOUKTIR2 1 Department of Electrical Engineering, University of Biskra, Algeria 2 Department of Electrical Engineering, University of Oum El Bouaghi, Alg naimi_djemaiyahoo.fr, Abstract Wind energy conversion systems are very different in nature from conventional generators. Therefore dynamic studies must be addressed in order to integrate wind power into the power system. Angular stability assessment of wind power generator is one of main issues in power system security and operation. The angular stability for the wind power generator is determined by its corresponding Critical Clearing Time (CCT). In this paper, the effect of wind power on the transient fault behavior is investigated by replacing the power generated by two main types of wind turbine, increasing gradually a rate of wind power penetration and changing the location of wind resources. The simulation analysis was established on a 14 bus IEEE test system by PSAT/Matlab, which gives access to an extensive library of grid components, and relevant wind turbine model. Keyword Angular Stability, CCT, Wind Turbine, Wind Penetration, PSAT. Introduction A power network is a complex system, which is vulnerable to disturbances. A transient short circuit fault is a very common disturbance in a power system 1. It upsets therotating machines in the vicinity of the fault, causing the speeds of these machines, and the power flows in the network to oscillate. When the short circuit is cleared by disconnecting the faulted line, the generators that have accelerated will decelerate and come back into synchronism with the rest of the system. If they do not, and the system becomes unstable, there is a risk of widespread blackouts and of mechanical damage to generators. So the critical clearing time (CCT) is the maximum time interval by which the fault must be cleared in order to preserve the system stability 2, 3. There is no doubt that wind power will play a predominant role in adding clean and nonpolluting energy to the countrys grid. However, as more wind turbines are connected to the grid, their impact on the power quality of services populated with wind generation is becoming more evident, so it is important to analyze the transient stability of power system including wind power stations 4. A three-phase fault is applied to a 14 bus IEEE test system, and cleared by disconnecting the affected line. In this paper, the focus is limited to determine Critical Clearing Time (CCT) for the several cases by observing the transit behavior simulation of a test system during grid faults using a Matlab power system analyze toolbox (PSAT) 5. The structure of this paper is as follows. First, the wind model is described briefly; also the wind turbine concepts are described. Then, the test system and the applied models are presented. The oscillation of a group of generators during a fault is analyzed by observing the transient behavior for following cases: A- Changing a wind source locates. B- Different generator technologies. C- Increasing gradually a rate of wind sources penetration. To conclude, the results are clarified on the basis of existing theories and comparison between different cases in order to choose a best case and avoid a worse one. Wind Model Wind energy is transformed into mechanical energy by means of a wind turbine whose rotation is transmitted to the generator by means of a mechanical drive train. The wind-power equation 6, 7 is given by: Pt=1/8d2v3 Cpwhere is the air density, r is the turbine radius, is the wind speed, and Cp is the turbine power coefficient which represents the power conversion efficiency and it is a function of the ratio of the rotor tip-speed to the wind speed, termed as the tip-speed-ratio (TSR). Such disturbances are the most common in the grid, the grid disturbances considered in this paper are of short duration, maximum a few hundreds of milliseconds. Since the considered grid disturbances are much faster than wind speed variations, the wind speed can he assumed constant. Therefore, natural wind variations need not be taken into account. The wind speed is set to a constant 15 m/s.Turbine Models There are many different types of wind turbines in use around the world, each having its own list of benefits and drawbacks 8. In this paper two main types of wind turbines are taken into account: A constant speed wind turbine (Fig. 1a), which consists of a grid coupled short-circuited induction generator 9. The wind turbine rotor is connected to the generator through a gearbox. The power extracted from the wind is limited in high wind speeds using the stall effect. No active control systems are used. A variable speed wind turbine with wound rotor induction generator (Fig. 1b) doubly-fed induction generator (DFIG). The rotor winding is supplied using a back-to-back voltage source converter 10. As in the first case, the wind turbine rotor is coupled to the generator through a gearbox. In high wind speeds the power extracted from the wind is limited by pitching the rotor blades. Figure 1a. Squirrel cage induction generator Figure 1b. Doubly-fed induction generatorTest System The test system for this study is presented in Fig. 2, it is derived from IEEE test system; this network consists of 14 buses, 5 generators, 11 loads and 83 branches. The transformers connecting generators to the grid are adjusted accordingly. Wind turbines are the 2 MW machines described above in section 2. Note that the generators do not represent a single machine but a group of strongly coupled generators and for this test system the total power is divided as follow: Table 1. Active power of test system generatorsGenerator N1 2 3 4 5 Power(MW) 61560602525The disturbance investigated is a three-phase short-circuit on Bus number 2. This three-phase fault represents the most severe disturbance for transient stability problems. It must be noted that all simulations are developed by PSAT (version 2.0.0 1). Results and Discussions Impact of Location In order to assume the impact of the wind power to angular stability of power system, we included a three phase symmetrical fault then we calculate the CCT corresponding to a case without wind source and others cases where a wind source is connected to test system by different Buses. Figure 2. Base case Without a Wind Source The Base Case represents the normal operation of the system without any wind power connected to the system. The critical fault clearing time (CCT) can be determined using transient simulations 3. For this case, the result is CCT = 196 ms. Fig. 3 shows the speed generators in comparison for a fault clearing time close to the critical clearing time. In Fig. 3b, the fault introduced has duration of t = 197 ms, so the time is exceeding the stability limit of CCT. Figure 3a. Rotor speed of all generators at t = 196 msFigure 3b. Rotor speed of all generators at t=197 msWith a Wind Source After that, one wind turbine generator is connected to system through a transmission line on different buses for evaluating their effect to the angular stability. Table 2. Results from the simulations for the angular stability on different locationsBus numberBus 1Bus 3Bus 8Bus 14CCT (ms) 186 187 263 220 Compared to the previous case where any wind source was connected, the integration of wind source has increased the transit stability when it was connected at BUS 8 or BUS 14, but on the contrary for cases of BUS 1 and BUS 3, so there is no general statement possible, if wind generation improves transient stability margins or if the impact is rather negative. The answer depends on location of wind resources and the problem has to be analyzed individually for each case. Effect of Type of Generator Technology In order to determine the effect of type of generator technology to transit behavior of grid, two types of generators are studied with keeping the same fault and the same location of wind source. Case 1: Fixed Speed The critical fault clearing time (CCT) can be determined using transient simulations. For this case, where wind source is connected to Bus N3 the result is CCT = 187 ms. Fig. 4 shows the speed rotor of all generators in comparison for a fault clearing time close to the critical clearing time. Figure 4a. Rotor speed of all generators at t=187 msCase 2: Variable Speed (DFIG Technology) The fixed speed generator added to Bus 3 is now disconnected and substituted by a doubly-fed induction generator (DFIG) having a same power (2MW). Thus, the change in the technology can be considered and analyzed. The analysis of the CCT results in an increased stability limit compared to Case 1 with only fixed speed generators in service. The time increases to CCT = 216 ms as shown in figure 5 .This means, that the transient network stability is enhanced when DFIG are connected instead of fixed speed generator.Figure 5a. Rotor speed of all generators at t=216 msFigure 5b. Rotor speed of all generators at t=217 msTable 3. CCT for two types of turbine technology on several busesBus N 1 3 8 14 CCT for fixed speed(ms) 186187263220 CCT for variable speed(ms)286216300227 According to results, it is very clearly that the DFIG generator increase the critical clearing time, consequently this type of generator presents best performance than a squirrel cage induction generator concerning the angular stability of grid connected to wind power, it is evident that the Wind power generation with DFIG provides better performance for angular stability after fault clearance owing to its ability to control reactive power. Effect of wind penetration In this section, the effect of wind power on the oscillations is investigated by gradually increasing the rate of wind source penetration while observing the transit behavior of system 11. Table 4. CCT for different rates of wind power penetrationRate of wind sources penetration (%) 3.18 6.7 14.01 21.65 22 Installed capacity of Wind sources (MW)24.9652.59109.90169.95 172CCT (ms) 271 229 151 97 00 From the results, it is concluded that the effect of wind power on power system oscillations depends on the rate of wind power penetration, it has been proven that a high level of wind power penetration such in our case study is must be lower than 22 % of total grid power, otherwise the test system lost its stability. Conclusion This paper has mainly focused on the assessment of the angular stability by determinate a critical clearing time (CCT), This was done by observing the behavior of speed generators of the test system included a three phase fault when changing several parameters. According to previously simulations, the following conclusions are obtained: There is no general statement possible, if wind generation improves transient stability margins or if the impact is rather negative. The answer depends on location of wind resources and the problem has to be analyzed individually for each case. The effect of type of generator technology in transit stability is very significant and the DFIG generator presents more performance than a squirrel cage induction generator. It has been proven that a high level of wind power penetration destabilize the power system when a very large part of the synchronous generation capacity is replaced by wind power. Finally, it very important to note that a calculation of a critical clearing time (CCT) in all previous simulations was done by several times which represent a wasting of effort and time so a numerical method of computation of (CCT) is very required for such transit stability studies. References 1. Sun T., Chen Z., Blaabjerg F., Voltage recovery of grid-connected wind turbines after a short-circuit fault, Annual Conference of the IEEE Industrial Electronics Society, Virginia, USA, 2003. 2. Saf