德国电网规程对风机联网及运行的要求

讨论德国电网规程关于风机的一些规定。在风电机组被大量应用的同时，几千MW的风电损失成了德国电力系统中的现实场景。问题的关键是电网故障时如何保证风机仍能连在电网上，即只要联网点的电压在15％Un以上风机和风电场就不允许解列。此外，在电网故障时风电机组应根据瞬时电压的情况提供一定的无功。而且，风机必须快速返回至正常操作。风机必须承受的频带为47，5～51．5Hz。对于德国网调而言，他们希望将来大型风电场应该象常规发电厂一样调度运行。     

高风电渗透互联系统的功角暂态稳定分析与惯性综合控制

具备虚拟惯性的变速风电机组接入电网,互联系统的暂态稳定控制将因惯性可控而更加灵活.首先推导含风电的两区域互联电力系统的线性化状态方程,分析风电机组的虚拟惯性作为系统运行可控参数对暂态功角特性的影响机理.其次,针对互联系统两侧区域电网,分别提出基于惯性调节的系统功角暂态稳定控制策略,通过协调两侧子区域惯性,提高系统功角暂态稳定.最后,通过建立高风电渗透下的两区域电网的仿真模型,验证所提控制策略通过灵活调节风电惯性,可显著改善区域互联系统的功角暂态稳定性.     

Dynamic security issues in autonomous power systems with increasing wind power penetration

Technical requirements set by the network operators nowadays include various aspects, such as fault ride-through capability of wind turbines during faults, voltage-reactive power control and overall control of the wind farms as conventional power plants. Detailed models for the power system as well as for the wind farms are therefore essential for power system studies related to these issues, especially when applied to non interconnected systems with high wind power penetration. Detailed generic models for three different wind turbine technologies - Active Stall Induction Generator (ASIG), Doubly Fed Asynchronous Generator (DFAG) and Permanent Magnet Synchronous Generator (PMSG) - are applied and issues regarding interaction with the power system are investigated. This paper provides conclusions about the dynamic security of non-interconnected power systems with high wind power penetration based on a complete model representation of the individual components of the system; three different types of conventional generators are included in the model, while the protection system is also incorporated. The load shedding following faults is finally discussed.     

大型风电机组和电力系统联网及相关问题

为了解决能源供应和二氧化碳排放等问题,实现可持续发展,风能是人类近期最有可能大规模开发和利用的可再生能源。介绍当前主要存在的风力发电机系统及其控制,随着风力发电的迅速发展,大容量的风电场联网运行是必然趋势。以丹麦某计划建设中的海上风电场为例,讨论风电场可能采用的联网方式。以ABB公司所做的德国某海上风电场的联网案例来对比分析直流联网和交流联网的各自特点。分析了风力发电机组联网后与电网间的相互影响的问题,从电力系统的角度而言,如果风能将不再被视为一个“不重要的”能源,那么,就需要考虑风力发电机组对于电力系统稳定性、电能质量和系统建模的影响;从风机保护的角度而言,需要考虑电力系统发生故障时,风力发电机组对电力系统的暂态响应。     

Dynamic behavior of an island power system with variable‐pitch wind turbines under high renewable energy penetration and high wind speed

High penetration of renewable energy in a power system may cause the problem of power dispatching and stability. The detailed dynamic behavior analysis for such a system is therefore important to the planning and operation of the power system. This study discussed the dynamic characteristics of an island power system with variable‐pitch wind turbines under high wind speed and high small hydraulic output power. The system primarily consisted of three diesel engine power generation systems, three constant‐speed variable‐pitch wind turbines, a small hydraulic induction generation system, and lumped static loads. The maximum penetration of renewable energy in this system could reach almost 60%. Detailed models based on MATLAB/Simulink were developed to cater for the dynamic behavior of the system. The results suggested that this island power system can operate stably in this operational mode with the help of variable‐pitch wind turbines. This study can serve as an important reference for planning, operation, and further expansion of island power systems. Copyright © 2014 John Wiley & Sons, Ltd.     

具有低电压穿越能力的风电机组测试故障典型实例分析

近年来,西北尤其是甘肃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。2011年以来国网公司西北分部和甘肃省调在酒泉千万千瓦风电基地共同组织开展了风电机组低电压穿越能力抽检验证工作,共进行33座风电场44台风电机组现场试验。通过对测试过程中遇到的风电机组脱网故障进行分析总结,找到了影响风电机组低电压穿越能力的主要因素,并结合实例对各影响因素进行分析阐述。目前,风电机组的硬件维护水平、主控制策略调整、软件设置和控制版本升级仍是影响并网风电机组低电压穿越能力的主要因素。     

基于风电机组健康状态的风电场功率分配研究

评价风电机组健康状态,合理分配风电场中风电机组的功率,对降低风电场的运维成本有着重要意义。首先,利用风电机组监控与数据采集(supervisory control and data acquisition, SCADA)系统中的风电机组历史运行数据,训练基于长短期记忆(long short-term memory, LSTM)网络的风电机组输出功率预测模型。然后,根据预测功率和风电机组实测输出功率的偏差幅值将风电机组的健康状态分为良好、一般、较差等三个类别。最后,综合考虑风电场中每台机组的健康状态、最大发电能力和电网调度部门对风电场下达的发电指令,建立目标函数和约束条件,采用遗传算法进行求解,得到分配给每台机组的功率。仿真结果表明,所提出的方法不仅能够根据风电机组的健康状态合理分配机组功率,而且能够满足调度中心下达的风电场总的发电功率。     

含大规模风电的电力系统小扰动稳定研究综述

针对风电并网对电力系统带来的小扰动稳定性问题,从对小扰动稳定性的影响和风机附加阻尼控制两方面对该领域的最新进展进行了综述。简述了小扰动稳定性的相关概念,介绍了风电机组的类型和模式。将目前的研究方法归纳为两类:基于确定性方法和概率分析方法,并分析指出了不同类型的风电机组对小扰动稳定性的影响及存在的问题。综合讨论了风机附加阻尼控制器提高系统阻尼的方法,提出了该领域需进一步开展的工作。     

Impact of FACTS controllers on the stability of power systems connected with doubly fed induction generators

The increasing power demand has led to the growth of new technologies that play an integral role in shaping the future energy market. Keeping in view of the environmental constraints, grid connected wind turbines are promising in increasing system reliability. This paper presents the impact of FACTS controllers on the stability of power systems connected with wind energy conversion systems. The wind generator model considered is a variable speed doubly fed induction generator model. The stability assessment is made first for a three phase short circuit without FACTS controllers in the power network and then with the FACTS controllers. The dynamic simulation results yield information on (i) the impact of faults on the performance of induction generators/wind turbines, (ii) transient rating of the FACTS controllers for enhancement of rotor speed stability of induction generators and angle stability of synchronous generators. EUROSTAG is used for executing the dynamic simulations.     

风电场接入电网的安全稳定分析

采用电力系统潮流算法,基于风电场出力与母线电压的P-V曲线,实现大容量风电场接入电网后电力系统的静态安全分析方法。建立异步风力发电机组的动态仿真模型,实现含有大容量风电场的电力系统动态稳定分析方法。结合风电场接入系统实例,提出保证电网和风电机组安全稳定运行的风电场运行控制方法。探讨通过控制负荷侧功率因数、采用动态无功补偿装置及进行故障后切除风电机组等措施提高电网动态稳定水平、改善风电场运行条件的有效方法。     

适用于风电经柔性直流并网系统的柔性耗能装置及控制策略

高压柔性直流输电技术可实现有功功率的双向控制,且无换相失败问题,是实现风电并网外送的重要手段之一。风电经柔性直流并网系统易发生交直流故障,故障期间风电系统持续输出功率,过剩的暂态能量危害系统的安全运行。针对风电经柔性直流并网系统的暂态能量耗散问题,提出了一种基于全桥子模块的柔性耗能装置(flexible energy dissipation device, FEDD)。为解决子模块充放电无法准确控制的难题,提出了柔性耗能装置的动态电压控制策略和暂态能量耗散策略,并兼顾了子模块电容能量平衡。根据FEDD的工作原理和控制策略,提出了设备主要参数设计方法。最后通过RTDS实验结果验证了柔性耗能装置能够准确吸收暂态能量,保证换流站平稳穿越交直流故障。     

Simulations of wind power integration with complementary power system planning tools

This paper describes a procedure for simulations of wind power integration in a deregulated power system with two complementary planning tools. The first planning tool is a joint market model (JMM) taking into account the day-ahead market and the regulating power market using 1 h average time steps. The second tool is the stepwise power flow (SPF) model simulating the frequency deviations and power balancing within the hour, e.g. based on 5 min average time steps. Input data is shared by the two tools, and the simulation results from JMM are used in the SPF simulations to ensure consistent results. JMM simulations are performed using two different scenarios for the development in the Nordic power system. The first scenario is the most likely development for 2010, and the second is a high-wind scenario assuming 10% of the electricity consumption in the Nordic countries supplied by wind power. Subsequently, a worst case 1 h period is selected from the JMM simulations, converted to the more detailed grid representation in SPF, and finally simulated and analysed with SPF.     

风电与火电“打捆”外送系统频率调控策略研究

风电与火电“打捆”外送是我国西部风电开发的一个重要特征.以一个具有典型意义的“风火打捆”仿真分析系统为例,研究了风电与火电之间的相互影响.围绕调差系数、前馈系数和伺服机构时间常数3个重要参数,分析了风功率波动条件下火电机组的一次调频特性.针对风机群体性脱网故障,提出了一种紧急提升火电机组功率的系统频率控制策略,通过监测风机脱网量和火电机组旋转备用量,计算火电机组的紧急提升功率量,将机组CCS由正常AGC控制切换为紧急提升功率的控制,实现减小系统频率波动幅度、提高频率稳定性的效果.针对电网侧不同的故障形式,比较了不同类型风机的响应特性.对固速风机在电网短路故障下发生转速失稳被过速保护切除的机理进行了较为深入的分析.     

海上风电机组故障容错运行研究现状分析

海上风电场可及性差,运行条件恶劣。风电机组故障率高,故障修复时间长且维护困难,一旦故障停运,经济损失巨大。统计并对比分析海上风电机组和陆上风电机组的历史运行数据,归纳海上风电机组关键部件的故障特点,分析风力发电机组常见的电气类故障及其对系统的影响。分别从软件容错、硬件容错两个方面总结现有海上风电机组容错运行的研究现状,归纳目前海上风电机组的容错方案,分析现有容错方案的应用可行性。进一步指出现阶段海上风电机组故障容错存在的主要问题,并对将来的研究热点进行了展望。     

Design of robust intelligent protectiontechnique for large-scale grid-connectedwind farm

This paper presents a design of robust intelligent protection technique using adaptive neuro-fuzzy inference system (ANFIS) approach to detect and classify the fault types during various faults occurrence in large-scale grid-connected wind farm. Also, it is designed to determine the fault location and isolate the wind turbine generators located in the faulted zone during fault occurrence and reconnect them after fault clearance. The studied wind farm has a total rating capacity of 120 MW, where it consists of 60 doubly fed induction generator (DFIG) wind turbines each has a capacity of 2 MW. Moreover, the wind farm generators are positioned in 6 rows, where each row consists of 10 generators. The impacts of fault type, fault location, fault duration, cascaded faults, permanent fault and external grid fault on the behaviours of the generated active and reactive power are investigated. Also, the impacts of internal and external faults in cases of different transition resistances are investigated. The simulation results indicate that, the proposed ANFIS protection technique has the ability to detect, classify and determine the fault location, then isolate the faulted zones during fault occurrence and reconnect them after fault clearance. Furthermore, the wind turbines generators which are located in un-faulted zones can stay to deliver their generated active power to the grid during fault period.     

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。     

大规模风电经LCC-HVDC送出的送端电网频率协同控制策略

针对大规模风电经电网换相型高压直流(LCC-HVDC)送出的送端电网所面临的严峻高频问题,充分挖掘风电潜在调频能力,提出一种风电与直流频率限制器(FLC)参与送端电网调频的协同控制策略。分析直流FLC参与送端电网调频的响应特性,刻画送端电网频率与风电机组功率的下垂关系,设计风电机组变转速与变桨距角相结合的一次调频控制方法。建立包括常规机组一次调频、风电机组下垂控制和直流FLC的频率响应综合模型,结合电网的频率稳定要求,采用灵敏度方法整定风电机组与直流FLC的调频参数,设计风电与直流FLC共同参与的频率协同控制策略。算例仿真结果表明：所提频率协同控制策略可有效降低高频切机、直流过载运行风险,提高送端电网的频率稳定性。     

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。     

考虑塔影与风切变的永磁同步风电系统最大风能跟踪控制策略

为了保证风电机组高效稳定运行,通过在转矩控制环节中引入模糊变增益的转速补偿转矩,有效地减轻了由塔影效应、风切变、风速中的随机脉动分量引起的风力机输出的机械转矩波动与按照最优叶尖速比法计算的参考转速的波动对永磁同步风力发电系统的影响,抑制了风电系统的低频震荡并保证了系统的稳定性。当考虑到轴系的摩擦损耗时,为了真正地实现最大风能跟踪,通过对最优叶尖速比进行修正,得出最大电磁功率所对应的准确的参考转速,使得机组运行在最大电磁功率对应的工作点处。在Matlab/Simulink下构建了直驱永磁同步风电系统的详细仿真平台,验证了该方法的正确性与有效性。     

风电接入系统稳定性分析及其可视化研究

随着我国风电的快速发展,带来了大规模风电接入系统的稳定性问题。介绍风电大量脱网对系统频率的影响,并阐述风机低电压穿越问题(LVRT)。通过对WSCC-3机9节点系统的可视化仿真,展示了电网故障期间各节点电压波动情况,定性分析了并网风机低电压穿越过程。此外,算例结果表明,基于PowerWorld软件的区域电压可视化技术,有助于调度运行人员直观、形象地掌握事故状态下的全网运行情况。