Maximum Power Point Tracking in Variable Speed Wind Turbine Based on Permanent Magnet Synchronous Generator Using Maximum Torque Sliding Mode Control Strategy

The present study was carried out in order to track the maximum power point in a variable speed turbine by minimizing electromechanical torque changes using a sliding mode control strategy. In this strategy, first, the rotor speed is set at an optimal point for different wind speeds. As a result of which, the tip speed ratio reaches an optimal point, mechanical power coefficient is maximized, and wind turbine produces its maximum power and mechanical torque. Then, the maximum mechanical torque is tracked using electromechanical torque. In this technique, tracking error integral of maximum mechanical torque, the error, and the derivative of error are used as state variables. During changes in wind speed, sliding mode control is designed to absorb the maximum energy from the wind and minimize the response time of maximum power point tracking(MPPT). In this method, the actual control input signal is formed from a second order integral operation of the original sliding mode control input signal. The result of the second order integral in this model includes control signal integrity, full chattering attenuation, and prevention from large fluctuations in the power generator output. The simulation results, calculated by using MATLAB/m-file software, have shown the effectiveness of the proposed control strategy for wind energy systems based on the permanent magnet synchronous generator(PMSG).

A Novel Modified Fuzzy-predictive Control of Permanent Magnet Synchronous Generator Based Wind Energy Conversion System

A wind energy conversion system(WECS)based on a permanent magnet synchronous generator(PMSG)is an effective solution for renewable energy generation in modern power systems.The main advantages of PMSG include high performance at high and low speeds,minimal control effort owing to lower rotor inertia,self-excitation,high reliability,and simplicity of structure compared with induction generators.However,the intermittent nature of wind energy implies that maximum efficiency is not obtained from this system.Accordingly,maximum power point tracking(MPPT)in wind turbine systems has been proposed to address this problem.Traditional MPPT strategies suffer from severe output power fluctuations,low efficiency,and significant ripples in turbine rotation speed.This paper presents a novel MPPT control strategy based on fuzzy logic control(FLC)and model predictive control(MPC)to extract the maximum power from a PMSG-WECS and control the machine-side and grid-side converters.The simulation results obtained from Matlab/Simulink confirm the superiority of the control model in eliminating the output power fluctuations of the wind generators and accurately tracking the maximum power point.A comparative study between conventional MPPT and control methods is also conducted.

Robust nonlinear control via feedback linearization and Lyapunov theory for permanent magnet synchronous generator-based wind energy conversion system

In this paper,the method for the nonlinear control design of a permanent magnet synchronous generator based-wind energy conversion system(WECS)is proposed in order to obtain robustness against disturbances and harvest a maximum power from a typical stochastic wind environment.The technique overcomes both the problem of nonlinearity and the uncertainty of the parameter compared to such classical control designs based on traditional control techniques.The method is based on the differential geometric feedback linearization technique(DGT)and the Lyapunov theory.The results obtained show the effectiveness and performance of the proposed approach.

Comparative Performance of Fixed-Speed and Variable-Speed Wind Turbine Generator Systems

In the early development of the wind energy, the majority of the wind turbines have been operated at constant speed. Subsequently, the number of variable-speed wind turbines installed in wind farms has increased. In this paper, a comparative performance of fixed and variable speed wind generators with Pitch angle control has been presented. The first is based on a squirrel cage Induction Generator （IG） of 315 kW rated power, connected directly to the grid. The second incorporated a Permanent Magnet Synchronous Generator （PMSG） of 750 kW rated power. The performances of each studied wind generator are evaluated by simulation works and variable speed operation is highlighted as preferred mode of operation.

A Fuzzy Logical MPPT Control Strategy for PMSG Wind Generation Systems

Making full use of wind power is one of the main purposes of the wind turbine generator control. Conventional hill climbing search （HCS） method can realize the maximum power point tracking （MPPT）. However, the step size of HCS method is constant so that it cannot consider both steady-state response and dynamic response. A fuzzy logical control （FLC） algorithm is proposed to solve this problem in this paper, which can track the maximum power point （MPP） quickly and smoothly. To evaluate MPPT algorithms, four performance indices are also proposed in this paper. They are the energy captured by wind turbine, the maximum power-point tracking time when wind speed changes slowly, the fluctuation magnitude of real power during steady state, and the energy captured by wind turbine when wind speed changes fast. Three cases are designed and simulated in MATLAB/Simulink respectively. The comparison of the three MPPT strategies concludes that the proposed fuzzy logical control algorithm is more superior to the conventional HCS algorithms.

永磁直驱型风机海上风电送出系统不对称接地及甩负荷电磁暂态研究

为明确海上风电交流送出系统过电压的特征与水平,需考虑风电机组的故障穿越特性。该文结合永磁直驱风机变流器的控制原理,提出海上风电送出系统不对称接地过电压的解析计算方法。基于PSCAD对风电机组进行精确电磁暂态建模与故障电压穿越测试,以国内某500 kV大规模海上风电工程为背景,仿真计算送出系统不对称接地及甩负荷过电压。结果表明:系统不对称接地过电压大小与风机正负序控制策略有关;海缆电网侧甩负荷将产生持续百ms的1.3 pu以上的暂态过电压,风机过电压保护动作延时越长,暂态过电压越严重。实际海上风电工程计算需紧密联系风机控制保护策略及其参数,并综合关键设备耐压水平进行评估,通过风机控制策略优化可以降低系统过电压水平。

虚拟惯量控制对直驱风电机组载荷影响的分析及评估

针对虚拟惯量控制诱发风电机组机械载荷的问题,开展虚拟惯量控制对采用直驱永磁同步发电机(D-PMSG)的风电机组载荷影响的理论分析和仿真评估研究。从叶片、塔筒等机械结构低阶模态出发,建立虚拟惯量控制下D-PMSG线性化多体动力学模型,并通过线性化多体动力学模型分析虚拟惯量控制对机组载荷的影响机理。采用软件联合建模方法,构建涵盖永磁同步电机及其控制、电网、机械和气动特性等的D-PMSG非线性机电耦合模型。依据冲击载荷最大值、最大变化幅度百分比及等值疲劳载荷等指标,通过所建立的非线性机电耦合模型仿真分析并量化评估虚拟惯量控制对机组冲击载荷和动态疲劳载荷的影响。结果表明,D-PMSG附加虚拟惯量控制后,电网侧频率突变会使得传动轴和塔底侧向出现显著冲击载荷,且其随虚拟惯量时间常数增大而增大,在湍流风运行工况下机组传动轴和塔底侧向等值疲劳载荷较无附加虚拟惯量控制均有所减小。

永磁同步风力发电系统的最大功率跟踪模糊分数阶控制

在“双碳”背景下,风电作为零碳电力和新能源发电的主力军,在助力社会全面绿色低碳转型方面发挥了关键性作用。在保证发电稳定的前提下实现风能的最大化利用,提升风力发电系统发电量至为重要。文中针对永磁同一步风力发电系统的最大功率跟踪(maximum power point tracking, MPPT)问题进行研究。首先建立了永磁同步风力发电系统的机理仿真模型,用两电平双PWM全功率换流器连接风力发电机与电网。然后基于以上模型,分别设计了整数阶PI控制器、分数阶PI"控制器、模糊分数阶PP控制器以实现MPPT控制。最后对以上控制策略进行了仿真研究。结果表明,无论在阶跃风速还是随机风速下,模糊分数阶PU控制器相较于其他两种均具有更出色的MPPT性能与更强的鲁棒性。

基于自抗扰控制策略的直接转矩风力发电系统研究

针对直接转矩控制的永磁直驱风力发电系统中系统未能较好地跟踪最大功率点的问题,提出将自抗扰控制策略加入风力发电系统机侧控制结构中以提高系统性能。基于风力机和永磁同步风力发电机数学模型,结合自抗扰控制的基本模型构建发电机自抗扰速度环,最后以Matlab/Simulink软件对所提控制策略进行仿真分析,对比传统PI控制直接转矩风电系统,自抗扰控制策略的引入可提升系统整体的抗干扰能力和跟踪性能。

A Review of Direct Driven PMSG for Wind Energy Systems

This paper presents a comprehensive overview study of the DDPMSG （direct driven permanent magnet synchronous generator） for wind energy generation system. Wind turbine controls are provided. The PMSG （permanent magnet synchronous generator） is introduced as construction and model. Configurations of different power converters are presented for use with DDPMSG in wind systems at variable speed operation and maximum power capture. Control techniques for the system are discussed for both machine-side and grid-side in details. Grid integration is provided with focus on how to insure power quality of the system and the performance at disturbances.

正十二边形矢量集的永磁同步发电机磁链预测控制

针对磁链预测问题,基于广义比例积分观测器原理设计磁链观测器,并基于此实现具有误差校正的磁链预测,提升磁链预测精度;针对备选电压矢量较少的问题,构造一种均匀对称分布的正十二边形矢量集,不仅增加可选矢量数量,而且矢量集的正十二边形分布特征有利于特定次开关谐波的消除。基于以上核心算法,最终为风电系统中PMSG设计FCS-MPFC方案,并通过实验验证所提方案具有较强的参数鲁棒性和较高的转矩控制精度。

基于转子动能调节的风电输出功率平滑控制策略比较与改进

湍流风况下,基于传统最大功率点跟踪模式控制的风电机组输出功率剧烈波动,会对电能质量及电网稳定造成负面影响,而通过调节风电机组转子惯性动能可平滑快速波动的输出功率。文中从风电机组转子惯性动能控制的关键参数功率参考值出发,通过建立系统传递函数,比较现有文献中提出的两种转子动能控制方法,即一阶滤波法和二阶滤波法,分析功率平滑控制的机理。在此基础上,提出了一种基于模糊控制器的新型变参数二阶滤波器转子动能控制策略。通过模糊控制器在线调整滤波参数,提升了在强湍流风况下的风电输出功率平滑效果,且有效避免了转速越限造成的电磁功率突变。最后,仿真与实验结果表明了所提转子动能控制策略相较于传统方法具有更好的功率平滑能力。

基于Boost变换器的D-PMSG风力发电系统MPPT控制

为了提高直驱永磁风力发电系统的最大功率点跟踪控制性能,通过对Boost占空比变化与风力机输出特性的关系分析,提出一种基于模糊梯度步长爬山搜索法,将风力机输出转速变化量和风力机输出功率变化量作为模糊控制器的输入量,Boost变换器的占空比作为模糊控制器的输出量,实现风力机最大功率点跟踪控制。建立了系统仿真模型并进行仿真验证,结果表明,模糊梯度步长爬山搜索法能实现直驱永磁风力发电系统的最大功率点跟踪控制,控制效果优于传统变步长爬山搜索算法。

自抗扰控制的九开关变换器提升分散式风电系统电能质量

为了提升高风电渗透率场景下分散式风电的电网故障穿越能力和系统抗扰性能,提出了九开关变换器型统一电能质量调节器方案。在分析九开关变换器数学模型的基础上,设计直流母线电压一阶自抗扰控制策略,可利用线性扩张状态观测器对扰动进行补偿,以降低直流电压的暂态超调;在分析永磁直驱风电机数学模型的基础上,网侧变换器采用线性自抗扰控制策略,以提高系统的动态性能。设计电压对称故障、不对称故障和连续故障3种电网复杂运行工况,对所提方案进行对比验证。研究结果表明,所提方案提升了分散式风电系统的响应速度,降低暂态超调约50%,实现了柔性故障穿越运行。

基于自抗扰技术的直驱风机高电压穿越控制策略

直驱式永磁同步风力发电机组(permanent magnet synchronous wind turbine generator,PMSG)全功率变流器是具有非线性、强耦合的复杂系统,易受到电网电压波动及非线性负载影响。为提高变流器直流母线电压的稳定性,提出一种基于改进线性自抗扰控制(linear active disturbance rejection control,LADRC)技术的PMSG高电压穿越控制策略。在传统LADRC基础上,将总扰动的微分扩张为一个新的状态变量,对总扰动的变化趋势进行提前观测,提高线性扩张状态观测器(linear extended state observer,LESO)的动态扰动观测能力。直流侧采用卸荷电阻优化方案,网侧变流器运行于无功补偿模式,为电网电压恢复稳定提供动态无功支撑。多种工况下的仿真结果表明,该控制策略缩小直流母线电压波动范围的同时减少了调节时间,能有效提升直流母线电压抗干扰能力,确保PMSG在高电压故障期间不脱网连续运行,同时提供一定的感性无功帮助电网电压恢复稳定。

基于风力发电系统低电压穿越技术研究

风力发电是目前应用广泛的新能源之一,当风电并网后若电网电压发生跌落时控制策略没有及时作出调整,将可能导致风机飞车,直流侧电容电压升高,严重威胁电力电子功率器件运行安全。本文研究了直驱永磁风力发电系统的运行机理和拓扑结构,阐述了风电并网所需满足的低电压穿越技术要求,并将模型预测控制算法应用于直驱永磁风力发电系统低电压穿越控制,构建了包含网侧和机侧电流的价值函数,通过滚动优化实现风速变化时的直流电压稳定和最大功率跟踪,通过MATLAB仿真平台验证了该方法的有效性。

基于阻尼控制器下永磁同步电动机SSI的抑制研究

变速风力发电机(WTG)包括双馈感应发电机(DFIG)和直接驱动永磁同步发电机(PMSG),由于其优良的控制特性而得到广泛的应用。在风机与电力系统进行并网时,风机中的PMSG捕捉到了次同步频率下的持续功率振荡,在这种情况下,PMSG的控制器将很快饱和,导致系统中持续的功率振荡。如果与附近任何涡轮发电机的扭转模式相匹配,则会激发严重的扭转振动。根据发电机的模型进行特征分析和仿真。最后在电源传感器的控制器上附加了一个补充同步阻尼控制回路以重塑阻抗,从而稳定次同步相互作用下的振荡频率。

基于直驱永磁风电系统的改进自适应滑模控制虚拟同步发电机策略

针对直驱永磁风力发电系统中,由逆变器间的等效输出阻抗和输电线路阻抗的差异导致传统虚拟同步发电机(virtual synchronous generator,VSG)控制的多逆变器并联功率不均分和环流抑制效果较差的问题,提出一种改进自适应滑模控制的多台VSG功率均分及环流抑制控制策略。根据总负荷容量和各逆变器容量计算给定功率,并根据给定无功功率实时调整虚拟阻抗值,补偿因线路阻抗差异引起的电压降落差,在αβ坐标系下分别对2台VSG展开滑模控制设计。基于逆变器输出电压与VSG参考电压之差设计滑模面,且基于李雅普诺夫(Lyapunov)稳定性理论设计由等效控制、切换控制和自适应补偿项构成的自适应滑模控制器。与传统方法相比,所提控制策略实现了功率均分且具有环流抑制能力,并提高了无功功率和VSG输出电压的分配精度。最后,在MATLAB/Simulink中验证了该控制策略的正确性和有效性。

基于PCHD永磁同步风力发电系统鲁棒控制

在分析永磁风力发电机组各组成部分的关系基础上,建立永磁同步电机(Permanent Magnet Synchronous Motor,PMSM)风力发电机组的数学模型;基于能量储存、配置互联和阻尼矩阵的非线性无源控制算法,建立永磁同步电机(PMSM)风电系统控端口Hamilton(ported-controlled Hamiltonian)系统模型,即永磁同步电机风电系统的PCHD模型。提出一种基于无源控制的PMSM风电系统鲁棒控制策略,并利用Simulink平台对所提出的控制策略进行仿真,结果表明该系统在输入机械功率多次变化时都能快速收敛到系统平衡点。

Residue Theorem based soft sliding mode control for wind power generation systems

This paper proposes a residue theorem based soft sliding mode control strategy for a permanent magnet synchronous generator(PMSG)based wind power generation system(WPGS),to achieve the maximum energy conversion and improved in the system dynamic performance.The main idea is to set a soft dynamic boundary for the controlled variables around a reference point.Thus the controlled variables would lie on a point inside the boundary.The convergence of the operating point is ensured by following the Forward Euler method.The proposed control has been verified via simulation and experiments,compared with conventional sliding mode control(SMC)and proportional integral(PI)control.