Intelligent control for large-scale variable speed variable pitch wind turbines

Large-scale wind turbine generator systems have strong nonlinear multivariable characteristics with many uncertain factors and disturbances. Automatic control is crucial for the efficiency and reliability of wind turbines. On the basis of simplified and proper model of variable speed variable pitch wind turbines, the effective wind speed is estimated using extended Kaiman filter. Intelligent control schemes proposed in the paper include two loops which operate in synchronism with each other. At below-rated wind speed, the inner loop adopts adaptive fuzzy control based on variable universe for generator torque regulation to realize maximum wind energy capture. At above-rated wind speed, a controller based on least square support vector machine is proposed to adjust pitch angle and keep rated output power. The simulation shows the effectiveness of the intelligent control.

Asymptotic Tracking Control for Wind Turbines in Variable Speed Mode

This paper presents a variable speed control strategy for wind turbines in order to capture maximum wind power.Wind turbines are modeled as a two-mass drive-train system with generator torque control.Based on the obtained wind turbine model,variable speed control schemes are developed.Nonlinear tracking controllers are designed to achieve asymptotic tracking for a prescribed rotor speed reference signal so as to yield maximum wind power capture.Due to the difficulty of torsional angle measurement,an observer-based control scheme that uses only rotor speed information is further developed for global asymptotic output tracking.The effectiveness of the proposed control methods is illustrated by simulation results.

PID-Type Fuzzy Controller for Grid-Supporting Inverter of Battery in Embedded Small Variable Speed Wind Turbine

Frequency and voltage of embedded variable speed wind turbine (VSWT) driving a permanent magnet synchronous generator (PMSG) is strongly affected by wind speed fluctuations. In practice, power imbalance between supply and demand is also common, especially when VSWT-PMSG is connected to a weak micro grid (MG). If load demand fluctuations become high, isolated MG may be unable to stabilize the frequency and voltage so that battery storage needs to be installed into the MG to adjust energy supply and demand. To allow flexible control of active and reactive power flow from/to battery storage, grid-supporting inverters are used. For a system that contains highly nonlinear components, the use of conventional linear proportional-integral-derivative (PID) controllers may cause system performance deterioration. Additionally, these controllers show slow, oscillating responses, and complex equations are required to obtain optimum responses in other controllers. To cope with these limitations, this paper proposes PID-type fuzzy controller (PIDfc) design to control grid-supporting inverter of battery. To ensure safe battery operating limits, we also propose a new controller scheme called intelligent battery protection (IBP). This IBP is integrated into PIDfc. Several simulation tests are performed to verify the scheme’s effectiveness. The results show that the proposed PIDfc controller exhibits improved performance and acceptable responses, and can be used instead of conventional controllers.

Increasing the Efficiency of Grid Tied Micro Wind Turbines in Low Wind Speed Regimes

Major problem with grid tied micro wind turbine is synchronization and wind variability. Due to this problem the stability of available grid gets reduced. The stability can be achieved by output power control of the turbine. Major part of many countries like India, the annual mean wind speed is not high. The rated wind speed of turbine remain around 11 m/s and cut in is around 3.5 m/s. Due to this problem we aimed to develop a sustainable wind energy system that can provide stable power supply even at the locations of low wind speed of 2 - 4 m/s. To address this issue, a momentary impulse or external torque to the rotor by external motor is one of the good options to maintain the momentum of blades and thus provide stability for sufficient time. Various theoretical calculations and experiments are conducted on the above method. This would increase the output power and also the efficiency of wind turbine. We show that Return-On-Investment will be high as compared with other grid connected turbines. Our proposed concept in the present study, if implemented properly, can help the installation of number of wind turbines even at domestic level. It also makes the consumers energy independent and promotes the use of wind as a source of energy and may enter as a rooftop energy supply system similar to solar.

基于E-Wind Turbine实验平台的风力发电控制系统

风力发电系统具有规模大、实际现场培训成本高、危险系数高等特点,因此基于风力发电仿真设备的风力发电控制研究是十分必要的。以E-Wind Turbine实验平台为例,详细介绍了变速、变桨距双馈风力发电系统实验平台的构成与控制策略的实现方法。基于S7-1200系列的PLC控制器,利用PORTAL STEP 7集成开发环境,实现了风机的偏航、转速控制以及功率控制。仿真实验结果表明,设计的风力发电控制系统可以有效地模拟实际风力发电机的各种控制要求,为风力发电控制策略的研究提供了一种有效手段。

Enhancement of DC-Link Protection of PMSG Based Wind Turbine under Network Disturbance by Using New Buck Controller System

Protection system for DC-link circuit of back-to-back converter of PMSG （Permanent Magnet Synchronous Generator） based wind turbine is essential part for the system to ride through a network fault in grid system. Voltage on the DC-link circuit can be increased significantly due to power unbalance between stator side converter and grid side converter. Increase of DC-link circuit voltage can lead to a damage of IGBT of the converter and control system failure. In this paper performance enhancement of DC-link protection of PMSG based Wind turbine by using new control system of buck converter is proposed. The buck converter is used to control supplied voltage of a breaking resistor to dissipate energy from the wind generator during network disturbance. In order to investigate effectiveness of the proposed DC-link protection system, fault analysis is performed in the simulation study by using PSCAD/EMTDC software program. In addition, comparative analysis between the proposed protection system and the conventional protection system using DC chopper is also performed.

Advanced Control of a PMSG Wind Turbine

In this work, an intelligent artificial control of a variable speed wind turbine (PMSG) is proposed. First, a mathematical model of turbine written at variable speed is established to investigate simulations results. In order to optimize energy production from wind, a pitch angle and DC bus control law is synthesized using PI controllers. Then, an intelligent artificial control such as fuzzy logic and artificial neural network control is applied. Its simulated performances are then compared to those of a classical PI controller. Results obtained in MATLAB/Simulink environment show that the fuzzy and the neuro control is more robust and has superior dynamic performance and hence is found to be a suitable replacement of the conventional PI controller for the high performance drive applications.

Variable speed wind turbine for maximum power capture using adaptive fuzzy integral sliding mode control

This paper presents a nonlinear control approach to variable speed wind turbine(VSWT)with a wind speed estimator.The dynamics of the wind turbine(WT)is derived from single mass model.In this work,a modified Newton Raphson estimator has been considered for exact estimation of effective wind speed.The main objective of this work is to extract maximum energy from the wind at below rated wind speed while reducing drive train oscillation.In order to achieve the above objectives,VSWT should operate close to the optimal power coefficient.The generator torque is considered as the control input to achieve maximum energy capture.From the literature,it is clear that existing linear and nonlinear control techniques suffer from poor tracking of WT dynamics,increased power loss and complex control law.In addition,they are not robust with respect to input disturbances.In order to overcome the above drawbacks,adaptive fuzzy integral sliding mode control(AFISMC)is proposed for VSWT control.The proposed controller is tested with different types of disturbances and compared with other nonlinear controllers such as sliding mode control and integral sliding mode control.The result shows the better performance of AFISMC and its robustness to input disturbances.In this paper,the discontinuity in integral sliding mode controller is smoothed by using hyperbolic tangent function,and the sliding gain is adapted using a fuzzy technique which makes the controller more robust.

变转速下基于改进多阶概率方法的风电齿轮箱故障诊断研究

阶次跟踪是一种有效的解决变转速故障诊断问题的方法,其关键前提是存在转速信号作为参考。然而,由于强背景噪声和弱谐波关系的影响,现有转速估计方法的准确性和自适应性有待进一步提高。因此,提出一种融合多传感器信号的改进多阶概率方法(MOPA)用以估计瞬时转速。首先,依据不同传感器信号的基频统一性和主导分量差异性,通过时频图瞬时切片归一化融合的方式,构建具有强谐波关系的时频图;其次,为消除时变工况下时频图中横纵方向上的间歇恒频和短时宽频背景噪声,提出滑动消噪方法;最后,基于处理后的时频图执行MOPA,实现瞬时转速自动估计,结合阶次跟踪解决风电齿轮箱变转速故障诊断问题。经实测数据验证,改进MOPA估计的瞬时频率的准确性和自适应性均优于对方法,平均绝对百分比误差为0.56%,均小于对比方法的15.73%、13.99%和1.21%。结合阶次分析诊断了变转速下风电齿轮箱异常。

实际风况下萨沃纽斯风力机集群性能及布局规律研究

为探究风况条件对萨沃纽斯风力机集群功率输出和安装方向的影响,基于变转速控制策略和计算流体力学仿真结果,获得了集群在我国8个典型站点不同安装方向下的输出功率,分析了集群在实际风况下的最佳布局规律,并验证了规律的普适性。仿真结果表明:在沈阳、厦门、昆明、呼和浩特、青岛、喀什、大连以及郑州8个站点合理安装集群,可使单台机组的输出功率分别提升至原来的1.14、1.23、1.31、1.20、1.21、1.24、1.12、1.11倍;对于有明显单一主风能风向的地区,集群应正对此方向摆放;对于两个主风能风向相位差较大的地区,需选择两者中周围风能更丰富的方向排布集群;对于有3个主风能风向、主风能风向不明显或风能分布比较均匀的地区,应先使机组相互格挡的方位避开风能相对集中区,再选择风能资源较丰富的方向排布集群。该研究可使实际风况下萨沃纽斯风力机集群耦合增益最大化,并为复杂风场条件下集群安装方向的选择提供参考。

Effective participation of wind turbines in frequency control of a two-area power system using coot optimization

In this paper,load frequency control is performed for a two-area power system incorporating a high penetration of renewable energy sources.A droop controller for a type 3 wind turbine is used to extract the stored kinetic energy from the rotating masses during sudden load disturbances.An auxiliary storage controller is applied to achieve effec-tive frequency response.The coot optimization algorithm(COA)is applied to allocate the optimum parameters of the fractional-order proportional integral derivative(FOPID),droop and auxiliary storage controllers.The fitness function is represented by the summation of integral square deviations in tie line power,and Areas 1 and 2 frequency errors.The robustness of the COA is proven by comparing the results with benchmarked optimizers including:atomic orbital search,honey badger algorithm,water cycle algorithm and particle swarm optimization.Performance assessment is confirmed in the following four scenarios:(i)optimization while including PID controllers;(ii)optimization while including FOPID controllers;(iii)validation of COA results under various load disturbances;and(iv)validation of the proposed controllers under varying weather conditions.

基于mRMR-GRU的变速恒频风电机组图像识别算法

为了精准识别变速恒频风电机组的运行状态,提出基于mRMR-GRU的变速恒频风电机组图像识别算法。通过分析变速恒频风电机组机械动态结构,获取整体变速恒频风电机组运行的重要控制部分;基于物联网技术,集成智能终端传感设备在特定结构中采集变速恒频风电机组图像;分析风电机组特定结构,生成变速恒频风电机组原始图像;基于直方图均衡方法对变速恒频风电机组图像进行增强处理,输出高分辨率采集图像;基于mRMR算法,定义特征变量的互信息,获得最具代表性和相关性的特征子集;融合GRU单元与mRMR值生成mRMR-GRU算法,优化图像识别网络结构,输出的风机图像状态识别结果。实验结果表明:设计算法MAPE值为4.46,RMSE值为3.57,图像识别准确度最高值为0.98,能够有效调节图像的特征变量,有效识别变速恒频风电机组图像存在的异常情况,且具有明显的图像像素点均衡效果与图像增强识别效果。

风力发电机高速旋转齿轮箱轴承变速故障信号检测研究

高速运转会导致轴承产生大量的振动和噪声,使得故障信号与背景噪声相混合,难以准确检测,一旦出现轴承变速故障将会威胁风力发电机的正常运行。为解决这一问题,提出风力发电机高速旋转齿轮箱轴承变速故障信号检测方法。通过小波阈值和经验模态分解方法,对采集到的风电机高速旋转齿轮箱轴承振动信号去噪处理;基于奇异值分解方法,提取风电机高速旋转齿轮箱轴承振动信号特征向量;通过灰狼算法-支持向量机模型,实现对其轴承变速故障检测。实验结果表明,所提方法的风力发电机高速旋转齿轮箱轴承变速故障检测的准确率高。

基于自适应遗传算法的风电机组变桨控制参数自寻优方法

当前,风力发电机组变桨系统采用传统PID参数整定方法,整定效率低、精确度和适应性差。为此,文章提出一种基于自适应遗传算法的风力发电机组变桨控制参数自寻优方法,包括变增益变桨PID参数自寻优和塔架加阻参数自寻优。其首先阐述了变桨控制系统基本原理;接着基于遗传算法根据风力发电机组不同机型对约束条件进行规划设计,涉及初始种群选择、自寻优算法约束及适应度函数设计;最后对传统参数整定方法与自寻优参数整定方法的响应曲线、仿真及现场运行结果进行对比分析。结果表明,相较传统方法整定的PID参数,自寻优变桨参数下发电机转速波动约降低10%,塔底My疲劳载荷约降低2%,对整定效率、精确度及适应性具有较好的改善效果。

大规模风电并网下抽水蓄能参与电网调频的模型预测控制策略

变速抽水蓄能机组在高比例风电并网的电力系统中具有深度参与频率调节的能力。针对短时风电功率波动引起电力系统频率扰动的问题,根据抽水蓄能机组不同的运行工况,提出抽水蓄能参与频率调节的模型预测控制策略。在发电运行时,利用风机的减载备用改善抽蓄机组因水锤效应引起的调频效果不佳的问题;在电动运行时,利用抽蓄机组快速响应的特点,有效平抑风电功率波动,提高风电机组的风能利用率。该策略在考虑抽蓄机组和风电机组各自约束条件的前提下,通过求解滚动时域内最优控制问题,协调各机组之间的有功出力分配,提高电网的调频性能。最后在Matlab/Simulink仿真平台对所提策略进行仿真验证,结果表明该策略能够有效改善抽水蓄能机组平抑风电功率波动时的调频效果。

基于遗传粒子群算法风电机组变速与变桨系统PI控制器设计

为了提升风电机组的控制精度并降低关键承载部件的载荷情况,通过遗传粒子群方法研究了变速与变桨系统比例积分(proportional integral,PI)控制器的设计。首先,采用泰勒级数将风电机组线性化展开为状态空间方程。然后,通过提取输入、输出和平衡点分别构建变速与变桨系统的数学模型。其次,分别采用Routh法和最小二乘法将变速与变桨系统辨识为低阶惯性系统和惯性时延系统。然后分别基于时间加权绝对误差积分准则和Chien-Hrones-Reswick法整定变速与变桨系统PI控制参数。最后,采用帕累托方法分配控制目标的权重关系并基于遗传粒子群算法优化变速与变桨系统PI控制参数,进而采用最小二乘法将其分别与风速和桨距角拟合构建自适应PI控制。结果表明:在变速控制中能够有效提升输出功率并抑制塔架顶部侧向振动;在变桨控制中能够有效平抑输出功率和发电机转速波动并降低叶片根部载荷情况。可见通过遗传粒子群方法设计的变速与变桨系统PI控制器具有良好的有效性和适用性。

基于改进转子转速和桨距角协调控制的变速风电机组一次调频策略

风电机组参与一次调频缓解了传统同步机组的调频压力,但其调频性能受功率跟踪方法的影响,不利于系统频率稳定.为此提出了基于改进转子转速和桨距角协调控制的一次调频策略,在全风速范围内预留调频所需功率裕度,在系统频率波动时能够提供快速且持久的有功支撑,实现对风电机组静调差系数的整定.对比分析不同减载控制策略下机组疲劳载荷和损伤等效载荷,结果表明所提策略可有效降低机组的疲劳载荷,延长使用寿命.最后,通过仿真验证了所提一次调频策略的有效性,频率改善效果优于传统一次调频控制,提高了风电场参与系统频率调节服务的一致性和可预测性.

漂浮式风机变桨距控制方法设计

海上漂浮式风机在风浪联合作用下做变桨控制,会对漂浮式风机的发电功率造成影响。传统的PID变桨控制效果差,存在发电功率波动较大的问题,为此,文中利用美国可再生能源实验室(NREL)提供的FAST软件,建立波浪载荷作用下的漂浮式风机的动力学方程,采用L-M法(Levenberg-Marquardt)对其中的系数进行辨识,并与FAST输出的高保真模型进行对比,验证所建立模型的准确性。其次,利用FAST提供的联合仿真平台设计一种基于遗传算法PID状态反馈的干扰自适应控制的方法,实现漂浮式风机变桨距的稳定控制。结果表明:与基于FAST的变桨距控制相比,基于遗传算法PID状态反馈的干扰自适应控制方法风轮转速的波动较小,输出功率的超调量更小,调节时间较短,更加稳定,而且能够减少漂浮式风机在平动方向和转动方向中横荡的波动,更适合海上漂浮式风机的变桨控制。

变工况下风电齿轮箱轴承动力学特性研究

轴承是风电机组齿轮箱的核心零部件,具有高转速、且转速和载荷随风速不断变化的特点,这些特点影响着轴承的动力学特性。本文针对风速变化引起的风电齿轮箱轴承动力学问题,建立了考虑轴承刚柔耦合的动力学模型,开展了变工况下轴承动力学特性研究,获得变速、变载条件下轴承保持架运动、应力等动态性能的变化规律。结果表明:转速和载荷的波动均会影响轴承保持架应力状态及其位移;转速和载荷的突然波动使保持架应力和位移增加。本文的研究为风电齿轮箱轴承动力学特性研究提供了数据支持。