基于IEC61400-25的智能风电综合控制系统设计

为实现智能电网环境下风电场的信息模型和电网友好型风电场的要求,提出了基于IEC61400-25的智能风电综合控制系统框架,指出了智能风电综合控制系统需解决的关键问题,建立了智能风电综合控制系统的信息模型,分析了电网IEC61970标准中的CIM模型和IEC61400-25风电场模型协调问题,提出了CIM模型和风电场模型的在线适配方法,给出了智能风电综合控制系统中的IED模型设计及信息接口设计方法,并针对智能风电综合控制系统实现中的关键问题提出了相应的解决方案。     

考虑风资源影响的风电场电压波动和闪变评估

风电并网后引起的电压波动和闪变水平可能超出国家有关标准,造成严重的电能质量问题,因此,在风电并网之前需对这两者进行评估。采用了一种新的评估方法。区别于国际电工标准(IEC61400-21)中电压波动与闪变的评估,此方法考虑了风电场的风资源情况对这2个指标的影响。对风电场在不同出力下由阵风引起系统的电压波动进行计算,并用IEC闪变仪计算短时间闪变值Pst。用所提方法和IEC标准对我国某一新建的风电场进行评估。结果表明,所提方法不仅能有效地进行电压波动与闪变评估,而且能更好地考虑风速变化对风电场带来的潜在影响。     

风电场的闪变计算与分析

按照国际电工标准(IEC61400-21)关于并网风电机组电能质量的规定,分析了风电场的闪变计算方法;推导出计算风电场容量的方法;并对闪变超标的单台机组以及闪变值符合电能要求的单台机组进行了对比分析.结果表明,单台机组的闪变系数接近限定值,机组的闪变值及系统短路容量的大小都是限制风电场容量的主要因素.     

基于IEC61850的光伏并网逆变器模型构建

针对分布式能源设备缺乏统一的通信标准问题,以光伏并网逆变器为例,建立了符合IEC61850 ed2.0标准的智能电子设备IED信息模型,以实现不同厂家生产的分布式能源设备之间的互操作性。文章详细分析了光伏并网逆变器应具备的功能,设计了该IED包含的逻辑节点、数据对象和逻辑设备,逐步建立了光伏并网逆变器的信息模型和信息交换服务,为符合IEC61850标准的分布式能源设备的开发提供参考。     

风电机组设计极端载荷外推法及其计算对比研究——关于IEC61400-1:2005版和1999版极端载荷计算研究

论文根据IEC61400-1:2005版规定,给出了大型风电机组载荷外推计算方法,并对2MW双馈式风电机组和3MW直驱式风电机组,进行了极限载荷外推的计算;同时,与IEC61400-1:1999版极限载荷要求计算的结果分别作了对比,结果分析发现无论哪种计算结果,都存在着随机性,而这种随机性对评估的准确性有很大的影响。新版IEC61400-1标准采用统计学的概率分布来描述载荷计算结果,经过算例的计算表明,这种载荷的计算比IEC61400-1:1999版的计算方法更具有科学性。     

风力发电场监控通讯标准IEC 61400-25及其设计思路

简要介绍IEC颁布的IEC 61400-25标准,给出了系统软件设计的思路。提出了模块化的系统构架;针对三种系统配置方式作出比较分析;为提高系统响应速度进一步讨论了数据存贮和检索的可选方式;最后对系统安全机制做出讨论并提出适当的解决方案     

微电网环境下飞轮储能系统信息建模与分布式运行机制

主要研究了在微电网具有分布式发电及设备运行机制环境中,飞轮储能系统的信息建模方法与分布式运行机制。应用IEC61850机制,建立微电网环境中的飞轮储能系统的信息模型,以将具有机电一体化设备特征的飞轮储能系统顺利转化为电力系统领域内的生产设备,并有效地与周围其他电力设备进行通讯与信息交换。重点说明了信息模型内部逻辑节点的建模方法。在基于IEC61850机制的飞轮储能系统信息模型基础上,进一步综合应用IEC61499分布式控制机制规划与描述FESS的充放电运行过程,研究了逻辑节点向标准功能块的转化方法。通过IEC61850和IEC61499对微电网中的飞轮储能系统综合应用,说明了2种机制结合应用的有效性,同时也为有效控制电力系统中飞轮储能系统的充放电过程提供技术途径。     

基于SRTM数据的地形测量方法研究

风电场地形是影响风电机组功率运行特性指标最主要的因素之一。本文根据国际电工委员会颁布的IEC 61400-12-1标准,基于SRTM地形数据与MATLAB软件,运用PCA(Principal Components Analysis)方法拟合出过风电机组塔基中心的最佳平面,计算出风电机组20倍叶轮直径范围内的地形坡度及高度偏差,并给出了工程实例的计算,为风电机组功率特性测试场地评估提供了相关参考。     

小型风力机测试标准综述

小型风力发电机能有效解决电网不能覆盖偏远地区农牧民的用电问题。但目前市场上的小风机质量参差不齐,加之农牧民缺乏对小风机技术的了解,因此保证小风机产品质量和农牧民利益问题亟待解决。风力发电机组测试认证标准为保证风力发电行业的健康发展发挥了重要作用,世界各国都在建立和完善本国的测试认证标准。本文介绍了现有关于小型风力机的测试标准,包括IEC 61400-2《小型风力发电机组设计要求》、IEC 61400-11:2006《噪声测试》、IEC 61400-12-1《功率性能测试》、《AWEA9.1小型风力发电机组性能与安全标准》、《BWEA小型风力发电机组性能与安全标准》,并在此基础上分析各标准在测试方法和数据处理上的差别。     

基于IEC 61400-12-1标准的风电机组年发电量计算方法的优化研究

在充分研究了IEC 61400-12-1标准中关于风电机组年发电量计算方法的基础上,结合概率论的相关理论,对该标准中计算方法存在的缺陷进行了分析,提出了一种优化算法,并对优化算法和标准算法的计算结果进行了对比分析。结果表明,在相同置信区间内,采用优化算法计算的年发电量结果的不确定度更低。     

基于PC测量仪器的风电机组电能质量测试系统

风电机组的电能质量测试不同于传统负荷的电能质量测试,需要排除电网特性和其他负荷的影响,并考虑不同风速对测试结果的影响．目前常规的电能质量测试仪器无法完成测试。风电机组电能质量测试系统选择高性能的PC测量仪器作为硬件采集平台．通过搭建虚拟电网排除电网结构及其他负荷产生的影响,采用适合风电机组的数字化闪变仪算法实现了风电机组的电能质量测试。测试系统通过对典型风电机组实际测试,证明测试系统完全能够满足风电机组电能质量测试标准IEC61400—21的要求。     

风力发电机组塔架螺栓连接公差问题研究

针对风力发电机组塔架法兰的螺栓连接,基于IEC 61400对其公差的要求和可能发生的平面度问题,采用有限元方法进行应力计算.结合实际风力发电机组法兰螺栓连接实例计算,对塔架法兰内倾量和平面度公差对筒壁和螺栓的影响进行总结,提出法兰内倾角公差设计方法,比较平面度公差对螺栓的影响,可为提高塔架法兰连接的可靠性提供更为严谨的...     

Model of wind shear conditional on turbulence and its impact on wind turbine loads

We analyse high‐frequency wind velocity measurements from two test stations over a period of several years and at heights ranging from 60 to 200 m, with the objective to validate wind shear predictions as used in load simulations for wind turbine design. A validated wind shear model is thereby proposed for flat terrain and that can significantly decrease the uncertainty associated with fatigue load predictions for wind turbines with large rotors. An essential contribution is the conditioning of wind shear on the 90% quantile of wind turbulence, such that the appropriate magnitude of the design fatigue load is achieved. The proposed wind shear model based on the wind measurements is thereby probabilistic in definition, with shear jointly distributed with wind turbulence. A simplified model for the wind shear exponent is further derived from the full stochastic model. The fatigue loads over different turbine components are evaluated under the full wind measurements, using the developed wind shear model and with standard wind conditions prescribed in the IEC 61400‐1 ed. 3. The results display the effect of the Wöhler exponent and reveal that under moderate turbulence, the effect of wind shear is most pronounced on the blade flap loads. It is further shown that under moderate wind turbulence, the wind shear exponents may be over‐specified in the design standards, and a reduction of wind shear exponent based on the present measurements can contribute to reduced fatigue damage equivalent loads on turbine blades. Although the influence of wind shear on extreme loads was found to be negligible, the IEC 61400‐1 wind shear definition was found to result in non‐conservative estimates of the 50 year extreme blade deflection toward the tower, especially under extreme turbulence conditions. Copyright © 2014 John Wiley & Sons, Ltd.     

Power quality assessment of wind turbines and comparison with conventional legal regulations: A case study in Turkey

Renewable energy sources have been investigated for use instead of conventional fossil fuels in many areas. Among these renewable energy sources, wind energy has come into prominence owing to the fact that it is a clean, sustainable and cost-effective type of energy. However, the connection of large wind farms to the grid may cause problems in terms of power quality due to the variability of the energy extracted from the wind. The mentioned power quality problems are generally taken into consideration after the grid integration of wind farms. However, the precautions that can be taken by means of the assessments before the installation of the turbines represent an easier and more economic way. In this study, the possible effects of the grid connected wind turbines on the power quality characteristics have been defined and the MATLAB based models have been constructed so as to calculate these effects. Particularly, fast voltage variations that are difficult to model due to their relations with the human factor have been analyzed in detail. It has been aimed that the models are suitable for use in practice while utilizing various standards such as IEC 61400-21 and IEC 61000-4-15 in order to setup the models. The analyses of the implementations that represent constraints for exploiting the wind resources in Turkey have been realized in terms of production and consumption with a case study. The realized calculations present the applicability of the model to grid conditions with different characteristics. It is also presented that the wind energy penetration can be increased without deteriorating the power quality of the grid with the use of the proposed model.     

An assessment of the impact of reduced averaging time on small wind turbine power curves,energy capture predictions and turbulence intensity measurements

The effect of varying the averaging time of measured data used to calculate wind turbine power curves is examined. The effects of reducing the averaging time from 10 to 1 min, as recommended for small wind turbines, are investigated using power performance data recorded using a 15 kW wind turbine. Test site data have been processed according to the relevant international standard, IEC 61400‐12‐1, to provide power curves and annual energy yield predictions. A number of issues are explored: the systematic distortion of the power curve that occurs as averaging time is decreased, the errors introduced by the use of 1 min averaged power curves to calculate energy yield and the reduction of turbulence intensity as averaging time is reduced. Recommendations for improved small wind turbine testing and energy yield calculation are given. Copyright © 2012 John Wiley & Sons, Ltd.     

Simulating subhourly variability of wind power output

As installed wind power capacity grows, subhourly variability in wind power output becomes increasingly important for determining the system flexibility needs, operating reserve requirements, and cost associated with wind integration. This paper presents a new methodology for simulating subhourly wind power output based on hourly average time series, which are often produced for system planning analyses, for both existing wind plants and expanded, hypothetical portfolios of wind plants. The subhourly model has an AR(p)‐ARCH(q) structure with exogenous input in the heteroskedasticity term. Model coefficients may be fit directly to high‐pass filtered historical data if it exists; for sets of wind plants containing hypothetical plants for which there are no historical data, this paper presents a method to determine model coefficients based on wind plant capacities, capacity factors, and pairwise distances. Unlike predecessors, the model presented in this paper is independent of wind speed data, captures explicitly the high variability associated with intermediate levels of power output, and captures distance‐dependent correlation between the power output of wind plants across subhourly frequencies. The model is parameterized with 1‐minute 2014 plant‐level wind power data from Electric Reliability Council of Texas (ERCOT) and validated out‐of‐sample against analogous 2015 data. The expanded‐capacity model, fit to 2014 data, produces accurate subhourly time series for the 2015 wind fleet (a 49% capacity expansion) based only on the 2015 system's wind plant capacities, capacity factors, and pairwise distances. This supports its use in simulating subhourly fleet aggregate wind power variability for future high‐wind scenarios.     

Uncertainties in the design of support structures and foundations for offshore wind turbines

Offshore wind industry has exponentially grown in the last years. Despite this growth, there are still many uncertainties in this field. This paper analyzes some current uncertainties in the offshore wind market, with the aim of going one step further in the development of this sector. To do this, some already identified uncertainties compromising offshore wind farm structural design have been identified and described in the paper. Examples of these identified uncertainties are the design of the transition piece and the difficulties for the soil properties characterization.Furthermore, this paper deals with other uncertainties not identified yet due to the limited experience in the sector. To do that, current and most used offshore wind standards and recommendations related to the design of foundation and support structures (IEC 61400-1, 2005; IEC 61400-3, 2009; DNV-OS-J101, Design of Offshore Wind Turbine, 2013 and Rules and Guidelines Germanischer Lloyd, WindEnergie, 2005) have been analyzed. These new identified uncertainties are related to the lifetime and return period, loads combination, scour phenomenon and its protection, Morison – Froude Krilov and diffraction regimes, wave theory, different scale and liquefaction.In fact, there are a lot of improvements to make in this field. Some of them are mentioned in this paper, but the future experience in the matter will make it possible to detect more issues to be solved and improved.     

Markovian power curves for wind turbines

This paper shows a novel method to characterize wind turbine power performance directly from high‐frequency fluctuating measurements. In particular, we show how to evaluate the dynamic response of the wind turbine system on fluctuating wind speed in the range of seconds. The method is based on the stochastic differential equations known as the Langevin equations of diffusive Markov processes. Thus, the fluctuating wind turbine power output is decomposed into two functions: (i) the relaxation, which describes the deterministic dynamic response of the wind turbine to its desired operation state, and (ii) the stochastic force (noise), which is an intrinsic feature of the system of wind power conversion. As a main result, we show that independently of the turbulence intensity of the wind, the characteristic of the wind turbine power performance is properly reconstructed. This characteristic is given by their fixed points (steady states) from the deterministic dynamic relaxation conditioned for given wind speed values. The method to estimate these coefficients directly from the data is presented and applied to numerical model data, as well as to real‐world measured power output data. The method is universal and is not only more accurate than the current standard procedure of ensemble averaging (IEC‐61400‐12) but it also allows a faster and robust estimation of wind turbines' power curves. Copyright © 2007 John Wiley & Sons, Ltd.