考虑调压裕度的风电场无功电压控制策略北大核心CSCD

针对风电场并网带来的电压稳定问题,文章提出了考虑调压裕度的无功电压控制策略。采用分层控制技术,首先通过无功整定层计算风电场无功输出参考值;其次在无功分配层考虑无功补偿装置与风电机组自身的调压裕度,选择相应的无功补偿方法,优先选用风电场配置的无功补偿装置进行无功调节。若补偿装置无法满足电压稳定要求,则根据各风电机组的运行状态,将无功补偿值按照无功容量比例算法进行分配,风电机组的网侧变流器采用自适应下垂控制以实现最大无功容量补偿。若无功缺额依然存在,需要对风电机组进行减载控制以实现对电网电压的无功支撑;最后,通过PSCAD/EMTDC仿真平台对所提策略的有效性进行了验证。     

基于风电机组聚类的风电场有功分层分配策略

针对风电场传统有功功率平均分配策略造成风电机组运行损伤差异性大、机组调整和启停次数多等问题,提出基于风电机组聚类的降功率分层分配策略。考虑实际风电机组调控能力,设计基于鲸鱼优化算法（WOA）的改进极限学习机（ELM）风电机组功率预测模型。构建实际风速、实际发电功率和预测功率的三维特征矩阵,提出基于模拟退火遗传算法（SAGA）的改进模糊C均值（FCM）聚类模型。以预测功率平均值和标准差、最大降功率值确定机群和机组调度优先级序列,构造“机群-机组”的两层分配策略,减少调整机组和停机机组的数量、提升风电机组损伤均衡性。结合某风电场实际工况,设计限功率模式不停机与停机的分配策略验证方案,对比分析3种不同策略的分配效果,算例结果验证了提出的分配策略的有效性。     

含柔性直流输电的海上风电场群无功控制策略

大规模海上风电场集群并网将对电力系统静态电压稳定产生影响。文章通过研究电网侧发生电压跌落或者上升,提出含柔性直流输电海上风电场集群的协同无功控制策略。该策略以电网故障节点电压快速恢复为目标,考虑了柔性直流输电方式的特点,充分利用交流海底电缆的输电特性,采用就地控制和远方控制相结合的无功控制策略。该策略首先确定含交直流柔性输电系统中的无功控制节点,并计算各节点相对电压跌落或上升节点的电压/无功灵敏度,然后基于无功补偿装置的运行状态、系统潮流分布,求解各节点控制的最大容量,最后利用遗传算法确定各控制节点的无功控制量。以改进IEEE 39节点系统为算例进行了仿真分析,结果表明,该策略提高了海上风电场集群对电网电压的支撑作用。     

基于风电机组无功响应速度的风电场闪变研究

针对风电机组无功响应速度对风电场并网点电压闪变的影响,从风力发电机组特性出发,基于DIg SILENT建立了含风电机组的电网仿真模型,研究风速波动时风机无功响应速度对风电场并网点电压波动与闪变的影响。算例结果表明:风电机组无功响应速度对并网点电压闪变的影响程度与系统短路容量密切相关,加快风电机组无功响应速度能有效抑制风电场并网点的电压闪变。     

计及无功资源调配成本的风电场优化技术

文章提出了一种计及无功资源调配成本的风电场无功优化方法,实现了风电场在不同运行工况下的无功优化配置。该方法以风电场无功调配成本和网损组成的综合成本最小为目标函数,考虑风电功率波动对系统电压的影响,建立基于机会约束规划的风电场无功优化模型,采用改进内点法进行求解。所提方法通过设置无功成本系数,使风电场能够按实际运行需求调用静止无功发生器、储能设备和风机的无功,并优化风电场网损。通过在电压约束条件中预留电压安全裕度防止系统电压发生越限。在某实际风电场中验证了所提方法的可行性和优越性。     

基于自适应模型预测算法的光伏并网逆变器无功电压控制策略研究

分布式光伏电源接入电网会引起并网点电压升高,传统无功电压控制方法控制精度低、响应时间长.文章将模型预测控制算法引入到无功电压控制算法中,并加入参数自适应环节,形成自适应模型预测算法.该算法可以很好地适应光伏逆变器,详细阐述了基于自适应模型预测算法的无功电压控制策略实现过程,并给出主要参数的计算方法.通过仿真和实验,验证...     

基于模型预测控制的配电网无功优化控制策略

摘要： 为了解决配电网中普遍存在的变压器过负荷以及用户电压偏低的问题,提出了一种基于模型预测控制（model predictive control,MPC）的配网无功优化控制策略。在分析配电网潮流特点的基础上,充分利用配变的过负荷能力来传输更多的有功,而无功则在低压电网中进行优化补偿。基于模型预测控制理论,采用季节时间序列的方法动态预测未来一天内的负荷大小,并考虑配变最大可用传输无功和无功补偿装置最大投切次数的约束,在通用数学模型系统（general algebraic modeling system,GAMS）上建立了以网损最小为目标函数的无功优化数学模型,依次给出无功补偿装置的动作情况。在IEEE14节点配网系统上的试验结果,验证了所提出的无功优化控制策略的有效性。     

考虑无功裕度的受端电网暂态电压稳定性控制方法研究

随着送端电网中大规模可再生能源发电容量的增加,在一定程度上导致外送系统无功支撑容量不足,使得系统电压出现波动。另外,无功功率不能在传输网络中长距离有效传输,增加了受端电网的无功平衡控制的难度。文章针对大规模外送系统中的受端电压波动所导致受端电网电压稳定性降低的问题,提出了一种基于无功裕度的受端电网暂态电压稳定性控制方法。首先,对系统无功裕度以及电压稳定性进行分析,得到系统静态电压稳定极限与无功需求容量的关系;然后,通过分析受端电网各节点无功需求特性,在能够允许受端电网电压最大波动的条件下,进行系统无功裕度的确定;再通过机器学习算法进行无功裕度控制,达到系统电压稳定控制的结果。通过仿真验证表明,采用文章所提出的基于无功裕度的受端电网暂态电压稳定性控制方法,能够精确地得到受端系统电压稳定工况,实现系统电压的稳定控制。     

基于数据分层预处理的短期风功率预测研究

良好的风速和风功率预测是解决风电并网问题的关键。针对样本数据中的无效点影响风功率建模问题,采用分层统计法对风功率进行统计分析后获得了风速—功率关系带,对功率进行修正,根据修正后的数据应用灰色—马尔可夫链模型进行预测,并与比恩法和经验公式法进行对比分析。结果表明,风功率分层统计法可有效地消除坏点数据,预测精度高。     

电网故障条件下风储联合系统无功自适应控制

针对电网三相对称故障条件下风电场电压不稳定的问题,文章提出了一种基于神经元的风储联合系统无功功率自适应控制策略,该策略以风储联合系统公共耦合点(Point of Common Coupling,PCC)的电压和电流为控制器的输入,采用Hebb学习算法作为自适应律,以获得准确的无功补偿。通过动态调整控制器的参数,使储能系统协调风电达到自适应输出无功功率的效果,提高系统在电网故障下的电压稳定性和风电故障穿越能力。最后,利用Matlab/Simulink仿真验证了该控制策略的有效性和正确性,与常规PI控制策略相比,文章所提出的控制策略可使风储系统迅速提供无功功率,PCC点的电压得到明显上升。     

风电场微观选址及发电量预测的探讨

对风资源评估、选址地面情况和风机位置的排布等影响风电场微观选址的因素进行了分析.阐述了风电场发电量的预测方法,通过实例说明如何使用相关软件来预测风电场发电量,并根据预测结果对风电场微观选址注意事项进行了探讨.     

Adjustment of wind farm power output through flexible turbine operation using wind farm control

When the installed capacity of wind power becomes high, the power generated by wind farms can no longer simply be that dictated by the wind speed. With sufficiently high penetration, it will be necessary for wind farms to provide assistance with supply‐demand matching. The work presented here introduces a wind farm controller that regulates the power generated by the wind farm to match the grid requirements by causing the power generated by each turbine to be adjusted. Further, benefits include fast response to reach the wind farm power demanded, flexibility, little fluctuation in the wind farm power output and provision of synthetic inertia. Copyright © 2015 John Wiley & Sons, Ltd.     

The effect of timescales on wind farm power variability with nonlinear model predictive control

Model predictive control techniques enable operators to balance multiple objectives in large wind farms, but the controller design depends on modeling effects that propagate at different timescales. This paper uses nonlinear model predictive control to investigate how wind farm power variability can be reduced both by varying ratios of three timescales impacting the system control and by inclusion of a power variability minimization measure in the controller objective function. Tests were conducted to assess how different timescale ratios affect the average farm power and power variability. Power variability measures are shown to be sensitive to the ratio of the incident wind period and the turbine time delay, particularly for cases with dominant incident wind frequencies. The average farm power increases in a series of steps as the controller time horizon increases, which corresponds to time horizon values required for wakes disturbances to propagate to downstream turbines. A second set of tests was conducted in which various measures of power variability were incorporated into the controller objective function and shown to yield significant reductions in farm power variability without significant reductions in farm power output. The controller was found to utilize two different approaches for achieving power variability reduction depending on the formulation of the controller objective function. These results have important implications for the design and operation of wind power plants, including the importance of considering the frequency components of wind during turbine siting and the potential to reduce power variability through the use of farm‐level coordinated control. Copyright © 2017 John Wiley & Sons, Ltd.     

Reactive power management and control of distant large-scale grid-connected offshore wind power farms

Reactive power management and control of distant large-scale offshore wind power farms connected to the grid through high-voltage alternating current (HVAC) transmission cable are presented in this paper. The choice of the transmission option is based on the capacity of the considered wind farm (WF) and the distance to the onshore grid connection point. The WF is made up of identical doubly-fed induction generators (DFIGs). Modelling and improved analysis of the effective reactive power capability of DFIGs as affected by various operational constraints are provided. In addition, modelling and analysis of the reactive power demands, balance, and control are presented. The minimum capacity and reactive power settings for reactive power compensation required for the system are determined. Possibility of unity power factor operation suggested by the German electricity association (VDEW) is investigated. A summary of the main outcomes of the work presented in this paper is provided in the conclusions section.     

风电系统的无功功率与电网电压稳定

论述了风电容量在占局部电网相当比例时,风电机组的无功功率调整与电网电压之间的关系,对于定速和变速风电机组的运行特性做了分析,提出了在需要做无功功率调整时风电机组应能满足的特殊要求。     

用于风电场并网中无功电压调节的UPFC仿真分析

以笼式异步电机为基础的风力发电机组并网运行时需要吸收大量无功功率,如果不能提供充分的无功补偿,会导致风电场电压跌落,部分风机脱离,系统无法正常运行。而统一潮流控制器（UPFC）具有控制线路潮流,提高电网稳定的作用,可以应用于风电并网之中。针对上述问题,在某一风场内的变风速条件下,用软件MATLAB/simu link建立基于恒速恒频异步发电机的风电机组并网模型并仿真,通过分析仿真结果,对比应用UPFC进行无功补偿前后风电场及电网的运行状态变化,证明UPFC可以调节带有风电场的系统无功功率和电压,维持电网稳定运行。     

Output power dispatch control for a wind farm in a small power system

Nowadays, a wind turbine generator (WTG) is required to provide control capabilities as the output power of WTG fluctuates. Under this scenario, this paper proposes an output power control method of a wind farm (WF) connected to a small power system using pitch angle control. In this control approach, the WF output power control is achieved by two control levels: central and local. In the central control, the WF output power command is determined by considering the frequency deviations and wind speeds using a fuzzy function. Then, the local output power commands for each of the WTGs are based on the proposed dispatch control. In the proposed dispatch control, the output commands of each WTG are determined by considering wind conditions for each of the WTGs. The simulation results by using an actual detailed model for the wind power system show the effectiveness of the proposed method. Copyright © 2010 John Wiley & Sons, Ltd.     

Reactive power control strategy for a wind farm with DFIG

Reactive power control strategy for a wind farm with a doubly fed induction generator (DFIG) is investigated. Under stator flux-oriented (SFO) vector control, the real power of the DFIG is controlled by the q-axis rotor current I_qr and the reactive power is mainly affected by the d-axis rotor current I_dr. To examine the effect of I_dr on stator reactive power Q_s and rotor reactive power Q_r, the DFIG is operated under five different operating modes, i.e, the maximum Q_s absorption mode, the rotor unity power factor mode, the minimum DFIG loss mode, the stator unity power factor mode, and the maximum Q_s generation mode. In pervious works, stator resistance R_s was usually neglected in deriving the d-axis rotor currents I_dr for different DFIG reactive power operating modes. In the present work, an iterative algorithm is presented to compute the d-axis rotor currents I_dr for the five reactive power control modes. To demonstrate the effectiveness of the proposed iterative algorithm, the rotor current, rotor voltage, stator current, real power and reactive power of a 2.5 MW DFIG operated under the five different operating modes are computed.