Oscillation analysis of a DFIG-based wind farm interfaced with LCC-HVDC

With the increasing capacity of wind farm, HVDC technology has become a promising transmission scheme for long distance transportation of large-scale wind power. However oscillation caused by this system will have a great influence on the security and stability of power system operation. In this paper, the oscillation of a doubly-fed induction generator(DFIG)-based wind farm interfaced with line commutated converter(LCC) based HVDC is discussed. Low-frequency oscillation and subsynchronous oscillation(SSO) are studied since these two oscillations are the particularly concerned oscillations in the stability study of power system in recent years. The model of a DFIG-based wind farm interconnected with LCC-HVDC is developed. The impact of drive train model's structure and parameters on the oscillation characteristics is analyzed. Eigenvalue and participation factor analysis are used to identify the three main modes, which include controller mode, electromechanical mode, and shaft mode. The effects of DFIG controller's parameters, wind speed and operating conditions of HVDC on those modes are studied. Electromagnetic transient simulations are performed to verify the results of the eigenvalue analysis.     

Security region based real and reactive power pricing of power system

This paper develops a novel model and an algorithm of security region based real and reactive power pricing of power systems. In the proposed model, the reactive power production cost is represented as the opportunity cost. The static voltage stability region in the cut set power space (CVSR) and the practical dynamic security region (PDSR) in the injection power space are used to represent the constraints of voltage stability and transient stability, so that the consideration of this kind of constraints in the optimization becomes very easy. In the proposed algorithm, a decoupled optimization and iteration method of active power production cost and reactive power production cost is suggested. According to the K-T optimality conditions, the prices of active power and reactive power, and the different components corresponding to the concerned security constraints are derived. The components of spot prices can reflect the influence of different node power injections on each kind of security constraints, so that through the node price all of the participants in power market can be stimulated to take an active part in maintaining the system security. An illustrative example on the New England 10-genetator 39-bus System is used to demonstrate the proposed method. Supported by the key research project of the National Natural Science Foundation of China (Grant No. 50595413)     

风电场并网系统的电压稳定性分析及改善措施

针对风电场并网带来的电压稳定性问题,以双馈风电机组为研究对象,根据双馈风电机组的运行特性,对风电机组的静态电压稳定和暂态电压稳定进行了理论分析,在Matlab/Simulink中建立了双馈风电场并网系统和静止无功补偿器模型,通过绘制双馈风电机组的P-V曲线,研究随着风电场出力的增加,电网静态电压稳定性的变化情况,并通过仿真验证了静止无功补偿器对于改善风电场并网系统的静态电压稳定性和暂态稳定性的作用.     

基于STATCOM的风电并网系统阻尼特性优化控制设计

针对当前风电场并网的暂态稳定性问题,在静止同步补偿器(STATCOM)的基本结构和数学模型的基础上,设计了一种含有灰狼优化算法(GWO)的功率振荡阻尼控制器,并利用GWO算法优化控制器参数来提高系统的暂态稳定性;最后,利用Matlab/Simulink对系统进行了建模仿真分析,对三相接地短路工况下运行的波形进行研究.结...     

大规模风电接入对电力系统暂态稳定性影响机理研究

根据双馈风机的暂态特性,详细分析将双馈风机视为恒功率源的可行性,并提出相关限制条件。分析风电机组接入引起潮流分布和系统惯量变化的2种情景,即通过减少同步机出力以平衡新增风电、停运部分同步机组平衡风电;并在此基础上,基于直流潮流模型和等面积定则,分析风电接入后对电力系统暂态稳定性的影响机理。最后,通过仿真分析验证该暂态稳定机理的正确性。     

高占比新能源电源接入区域电网的无功优化策略研究

从高占比风电、光伏接入电网运行的安全性和稳定性等方面综合考虑,建立了以电压偏移量和网损最小为目标的无功优化模型。利用MATLAB软件对风电、光伏电站接入IEEE-33节点系统进行无功优化仿真分析,采用多目标粒子群（MOPSO）算法进行无功优化调度方案求解。基于Pareto前沿解的MOPSO算法可为决策者根据不同需求提供方案,并且同时达到提高测试系统的电压稳定性、降低网损的目标,验证了所提优化策略的有效性。     

Security region based security-constrained unit commitment

As the issues of security and stability of power systems are becoming increasingly significant,it is necessary to consider the constraints of the static voltage stability and transient stability,which are closely related to the active power dispatch of power systems,in the daily power dispatch,i.e.the unit commitment.However,due to the complexity of these constraints and limitation of the existing analysis methods,there has been no unit commitment model reported so far that can deal with these security constraints.On the other hand,as lack of effective measures to evaluate the security margin of dispatch schemes,it is difficult for power system operators to integrate both the security and economy of power systems in unit commitment.To resolve the above-mentioned issues,a security region based security-constrained unit commitment model is presented in the paper,which gives consideration to both the security and economy of power systems.For the first time,the active power flow constraint,the static voltage stability constraint and the transient stability constraint are taken into account in unit commitment at the same time.The model presented in the paper takes the operating cost,the branch transmission capacity margin,the static voltage stability margin and the transient stability margin as sub-objectives.By adjusting the weighting factors of sub-objectives,it is convenient to adjust the preference on the security and economy of power systems and reach a balance.The IEEE RTS-24 test system is adopted to validate the correctness and the efficiency of the proposed model.     

复功率注入空间的电力系统概率安全性指标研究

为弥补电力系统安全性分析存在的不足,对电力系统概率安全分析进行了研究.在复功率注入空间提出了一种反映电力系统概率安全性的指标模型,该指标模型在现有研究成果的基础上,考虑了无功功率注入和负荷中感应电动机比例不确定性的影响.同时,根据复功率注入空间动态安全域超平面的迁移特性,推导了指标简化计算方法.仿真计算表明,该指标能够全面反映电力系统的安全性状况,具有合理性.     

Dynamic security risk assessment and optimization of power transmission system

The paper presents a practical dynamic security region (PDSR) based dynamic security risk assessment and optimization model for power transmission system. The cost of comprehensive security control and the influence of uncertainties of power injections are considered in the model of dynamic security risk assessment. The transient stability constraints and uncertainties of power injections can be considered easily by PDSR in form of hyper-box. A method to define and classify contingency set is presented, and a risk control optimization model is given which takes total dynamic insecurity risk as the objective function for a dominant contingency set. An optimal solution of dynamic insecurity risk is obtained by optimizing preventive and emergency control cost and contingency set decomposition. The effectiveness of this model has been proved by test results on the New England 10-genarator 39-bus system. Supported by the key research of the National Natural Science Foundation of China (Grant No. 50595413) and The National Basic Research Program of China (973 Program) (Grant No. 2004CB217904)     

考虑工频过电压的海上风电场无功配置优化方案

工频过电压是威胁线路安全稳定运行的重要因素。可以利用电磁暂态仿真软件ATP-EMTP对海上风电场系统及其送出线路进行建模,对工频过电压进行计算和分析。研究表明：0.97 p.u.、1.00 p.u.、1.07 p.u.3种情况下过电压水平均与线路长度成正比;系统侧甩负荷时过电压水平远大于风场侧甩负荷。对海上风电场中变压器、海缆、风电机组的无功损耗进行分析,结合对过电压的计算和分析以及相关标准规定,提出了一种简单实用的海上风电场无功配置方案。该方案可满足对工频过电压的限制,且可满足风电场无功需求。     

含双馈感应电机风电场的动态等值

实际风电场包括多台风电机组,对其机械和机电特性动态建模,需要引入大量微分方程,计算量较大。文章提出并实现了一种双馈感应风机机电暂态过程的等值算法。对风力机、传动系统、感应发电机、变流器及控制系统分别进行合并。考虑了风速在额定值以下或以上时,风力机采取速度控制和功率控制策略,分两种情况等值风速和风能利用系数。分别考虑电网故障和风力机风速扰动,比较等值前后风电场出口电压和功率,以及电网中同步发电机功角和频率。仿真结果表明,所提等值算法误差小,计算效率高,对风电系统暂态稳定分析具有良好的应用效果。     

考虑不确定性的电热耦合多能微网系统概率潮流计算

多能微网系统结构及设备耦合关系复杂,接入新能源的不确定性为系统运行带来巨大挑战。基于Beta拟合的光伏发电模型和两参数威布尔分布的风力发电模型,采用分解求解法进行了多能耦合潮流计算。然后对33节点电网和33节点热网耦合的多能源系统进行了算例分析,利用蒙特卡洛法提取不确定性样本,进一步提出了考虑光伏、风电和电、热负荷不确定性的概率潮流计算方法。最后运用该方法完成了概率潮流的算例分析,从概率潮流计算方法和各子网络的潮流计算结果两方面验证了方法的有效性。     

电网电压不平衡下的D-PMSWG系统MPC-VSG时域优化控制

当电网电压不平衡时,传统的VSG恒定有功以及恒定无功控制策略,在电网电压跌落和恢复期间频率响应和暂态稳定性欠佳。为解决这一问题,提出了一种电网电压不平衡下的直驱永磁同步风力发电（D-PMSWG）系统MPC-VSG时域优化控制策略。该策略将不平衡电网电压下的虚拟同步机控制（VSG）与模型预测控制（MPC）相结合,并对VSG转子运动方程的转子角频率与转矩建立了MPC预测模型,通过优化预测时域,调整了频率环节、阻尼环节和反馈控制惯量环节系数,得到了最优预测时域输出向量以及下一时刻的控制输入向量。与传统方法相比,所提出的方法在电压跌落、电压恢复瞬间的频率响应,以及功率的暂态特性,都得到了良好的改善。最后,在Matlab/Simulink中验证了不同控制目标下该控制策略的正确性和有效性。     

薄膜结构抗风性能概率评估方法

为研究薄膜屋盖结构不同抗风需求的超越概率评估方法,以重庆地区为例,借鉴PEER基于性能的抗震设计方法,考虑风场随机性,统计重庆地区近十年每月最大风速样本概率分布特征,获得由多项式拟合的设计风速危险性曲线.用Davenport谱表示水平风速谱,推导出风速谱危险性曲线,并用五次多项式进行拟合.考虑薄膜屋盖结构的非线性特征,近似将屋盖结构抗风需求(竖向位移限值)的平均值与风速谱值关系采用幂函数表示,推导出薄膜屋盖结构风载下不同法向变形需求值的年平均超越概率表达式.以平坦薄膜屋盖为例,采用自回归模型的线性滤波器法(AR法)模拟生成30条对应不同风压的脉动风速时程,对屋盖进行动力响应分析,通过计算,获得不同变形需求下薄膜屋盖风振响应的超越概率及最大响应重现期.结果表明:多项式拟合对于薄膜屋盖抗风需求的年平均超越概率表达式推导有较好的简化效果;基于性能的薄膜屋盖结构抗风概率评估方法通过少量结构分析可以得到结构不同位移需求的超越概率评估值.     

联合条件下风力发电风速预测

风速性质直接影响风力发电的功率,确定性预测在很多方面无法满足当前需要,而概率性预测比较符合实际,具有更强的实用性．采用以当前时段实测风速和下一时段预报风速为联合条件的离散预报误差概率统计模型（forecasterrorprobabilitydistribution,FEPD）,从而预测短时（功率预测前几小时）风速,通过得到风速数据,在短时时段覆盖内,就能够预测风力发电的功率．实例证明,以风速为基础从而预测风力发电功率是一种有效的方法．     

A novel optimization method of transient stability emergency control based on practical dynamic security region (PDSR) of power systems

Recentyearsseetensoftheoccurrencesofwidespreadblackoutsintheworldthatcausedtremendouseconomiclossestosocietyandseriousequipmentdamagestotheutility[1].InChina,theimpoundmentoftheThreeGorgesPowerStation,theimplementationofpowertransmissionfromwestChinatoeastChinaandthenationwideinterconnectionsofregionalpowersystemswillmaketheproblemofpowersystemsecuritymoresevere.Inordertoavoidsuchwidespreadblackouts,themosteffectivemethodsareonlinesecurityassessmentandpreventivecontrol.Howeverconsideringthe…     

Optimum line reclosing time for the enhancement of interconnected power system stability

0　INTRODUCTIONWiththegrowthoflargeinterconnectedpowersystemowingtothebenefitsofpowermarketderegulation ,thereisanurgentneedtoimplementtransientstabilitycontrolforaninterconnectedpowersysteminemergencyforavoidingthecatastrophicresult .Automaticlinereclosingschemesasappliedintheextra high voltagepowersystemisoneofeconomicalandeffectivemeanstomaintaintran sientstabilityandsynchronism[1] .Becausethemajority(6 0 %～ 80 % )oftransmissionlinefaultsareofatransitorynature[2 ] ,automaticlinere clos…     

考虑输配交互的含风电场电力系统多目标动态随机模糊最优潮流

提出一种考虑输配交互的含风电场电力系统多目标动态随机模糊最优潮流方法。突破传统输配网最优潮流独立计算且配网一般以负荷计及的现状,考虑主动配电网与输电网的双向潮流交互特性和风电注入功率随机模糊性,兼顾系统经济、低碳、降损多目标优化,考虑输配网静态安全,基于随机模糊机会约束规划建立含风电场电力系统输配交互多目标动态随机模糊潮流模型;提出在随机模糊模拟、牛顿拉夫逊法与前推回代法求解输配系统随机模糊潮流基础上,通过输配网节点功率和电压考虑输配交互特性,基于Look-ahead和NSGA-I获取各时段Pareto解,采用最大满意度法决策,从而提出模型求解算法。改进的IEEE 30节点输电系统与IEEE 33节点配电系统的算例仿真结果表明了文中提出的模型和算法有效性和优越性。     

通过网络参数调控提高FACTS的稳定性

研究了灵活交流输电系统（ＦＡＣＴＳ）的稳定控制问题。通过电力网络结构控制及临界能量分析，提出网络结构参数控制对策及评价方法，借以提高系统的暂态稳定性。并实际应用于１０机３９母线系统，考察和验证电力网络结构控制对提高电力系统暂态稳定性的有效性     

SVC动态特性对风电场接入电网电压稳定性的影响

以多数风场配置的无源无功补偿装置为例,构建TCR/MCR型SVC仿真控制模型,研究它们在风场动稳和暂稳期间的响应特性,分析它们对风电运行电压稳定的改善作用仿真结果表明TCR/MCR型SVC对于提高风电场电压稳定性均具有明显的作用,但前者能更快地跟踪电压波动,快速调整无功输出,更好地抑制了电压波动.