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).

Performance analysis of 20 Pole 1.5 KW Three Phase Permanent Magnet Synchronous Generator for low Speed Vertical Axis Wind Turbine

This paper gives performance analysis of a three phase Permanent Magnet Synchronous Generator (PMSG) connected to a Vertical Axis Wind Turbine (VAWT). Low speed wind condition (less than 5 m/s) is taken in consideration and the entire simulation is carried in Matlab/Simulink environment. The rated power for the generator is fixed at 1.5 KW and number of pole at 20. It is observed under low wind speed of6 m/s, a turbine having approximately1 mof radius and2.6 mof height develops 150 Nm mechanical torque that can generate power up to 1.5 KW. The generator is designed using modeling tool and is fabricated. The fabricated generator is tested in the laboratory with the simulation result for the error analysis. The range of error is about 5%-27% for the same output power value. The limitations and possible causes for error are presented and discussed.

Integrated Equivalent Model of Permanent Magnet Synchronous Generator Based Wind Turbine for Large-scale Offshore Wind Farm Simulation

The high-speed simulation of large-scale offshore wind farms(OWFs) preserving the internal machine information has become a huge challenge due to the large wind turbine(WT) count and microsecond-range time step. Hence, it is undoable to investigate the internal node information of the OWF in the electro-magnetic transient(EMT) programs. To fill this gap,this paper presents an equivalent modeling method for largescale OWF, whose accuracy and efficiency are guaranteed by integrating the individual devices of permanent magnet synchronous generator(PMSG) based WT. The node-elimination algorithm is used while the internal machine information is recursively updated. Unlike the existing aggregation methods, the developed EMT model can reflect the characteristics of each WT under different wind speeds and WT parameters without modifying the codes. The access to each WT controller is preserved so that the time-varying dynamics of all the WTs could be simulated. Comparisons of the proposed model with the detailed model in PSCAD/EMTDC have shown very high precision and high efficiency. The proposed modeling procedures can be used as reference for other types of WTs once the structures and parameters are given.

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.

The Multi-Objective Optimization of AFPM Generators with Double-Sided Internal Stator Structures for Vertical Axis Wind Turbines

The axial flux permanent magnet(AFPM)generator with double-sided internal stator structure is highly suitable for vertical axis wind turbines due to its high power density.The performance of the AFPM generator with double-sided internal stator structure can be improved by the reasonable design of electromagnetic parameters.To further improve the overall performance of the AFPM generator with double-sided internal stator structure,multivariable(coil widthω_(c),permanent magnet thickness h,pole arc coefficient α_(p) and working air gap l_(g))and multi-objective(generator efficiencyη,total harmonic distortion of the voltage THD and induced electromotive force amplitude EMF)functional relationships are innovatively established.Orthogonal analysis,mean analysis and variance analysis are performed on the influence parameters by combining the Taguchi method and response surface methodology to study the influence degrees of each influence parameter on the optimization objectives to determine the most appropriate electromagnetic parameters.The optimization results are verified by 3D finite element analysis.The optimized APFM generator with double-sided internal stator structure exhibits superior economy,stronger magnetic density,higher efficiency and improved power quality.

Control Strategy of Wind Turbine Based on Permanent Magnet Synchronous Generator and Energy Storage for Stand-Alone Systems

This paper investigates a variable speed wind turbine based on permanent magnet synchronous generator and a full-scale power converter in a stand-alone system.An energy storage system(ESS)including battery and fuel cell-electrolyzer combination is connected to the DC link of the full-scale power converter through the power electronics interface.Wind is the primary power source of the system,the battery and FC-electrolyzer combination is used as a backup and a long-term storage system to provide or absorb power in the stand-alone system,respectively.In this paper,a control strategy is proposed for the operation of this variable speed wind turbine in a stand-alone system,where the generator-side converter and the ESS operate together to meet the demand of the loads.This control strategy is competent for supporting the variation of the loads or wind speed and limiting the DC-link voltage of the full-scale power converter in a small range.A simulation model of a variable speed wind turbine in a stand-alone system is developed using the simulation tool of PSCAD/EMTDC.The dynamic performance of the stand-alone wind turbine system and the proposed control strategy is assessed and emphasized with the simulation results.

Research on Slot-pole Combination in High-power Direct-drive PM Vernier Generator for Fractional Frequency Transmission System

Offshore wind energy is an important part of clean energy,and the adoption of wind energy to generate electricity will contribute to the implementation of the carbon peaking and carbon neutrality goals.The combination of the fractional frequency transmission system(FFTS) and the direct-drive wind turbine generator will be beneficial to the development of the offshore wind power industry.The use of fractional frequency in FFTS is beneficial to the transmission of electrical energy,but it will also lead to an increase in the volume and weight of the generator,which is unfavorable for wind power generation.Improving the torque density of the generator can effectively reduce the volume of the generators.The vernier permanent magnet machine(VPM) operates on the magnetic flux modulation principle and has the merits of high torque density.In the field of electric machines,the vernier machine based on the principle of magnetic flux modulation has been proved its feasibility to reduce the volume and weight.However,in the field of low-speed direct-drive machines for high-power fractional frequency power generation,there are still few related researches.Therefore,this paper studies the application of magnetic flux modulation in fractional frequency and high-power direct-drive wind turbine generators,mainly analyzes the influence of different pole ratios and different pole pairs on the generator,and draws some conclusions to provide reference for the design of wind turbine generators.

基于滑模变结构的风电机组一次调频算法研究

针对并网风电场中,经典一次调频控制方法存在抗干扰能力弱、机组易脱网的问题,提出一种基于滑模变结构的风电机组一次调频控制算法。首先,在永磁同步风电机组工作原理的基础上,建立含有大电网的风电机组模型。其次,为了解决传统比例积分微分(proportional integral differential,PID)控制下抗干扰能力弱的问题、引入经典滑模变结构控制器。然后,针对经典滑模变结构控制器导致执行机构存在抖振较多的缺点,提出一种基于sigmoid函数趋近率的滑模变结构一次调频控制算法。最后,通过MATLAB/Simulink对风电机组一次调频进行建模仿真,并与经典控制算法相比,验证了所提算法的可行性,在风速波动和电网故障的环境下,滑模变结构一次调频控制算法更具有效性。

包含串补的并网直驱风电场振荡稳定性及可行域分析

串补装置广泛存在于电力系统中,含串补的大规模直驱永磁同步发电机(PMSG)构成的风电场并网系统存在次同步振荡范畴的小干扰失稳风险。针对上述现象,该文首先构建包含PMSG网侧换流器控制模型、锁相环控制模型以及含有串补装置的线路动态模型的并网系统全阶模型及等效模型。然后在不同的时间尺度下对等效模型进行化简,运用劳斯-赫尔维茨判据求得各时间尺度场景下并网系统的稳定性判据,从机理上解释了并网系统中各运行参数和控制参数之间的联系及其对系统稳定性的影响。进一步通过一个包含15台PMSG风电机组的并网风电场验证了该文推导的稳定判据的正确性。最后基于可行域的分析,直观地讨论了串补线路和其他参数对系统稳定性的影响。

并联永磁同步风电机组小干扰稳定性分析

采用平均磁链定向控制多台永磁同步风电机组进而构造分频发电系统是未来陆上尤其是海上风电的汇集方案之一,但对该模式下多台风电机组间稳定性的研究鲜有文献涉及。针对此问题,基于特征值分析法,研究了平均磁链定向控制的永磁同步风电机组之间的小干扰稳定性。首先,基于高压大容量直驱式永磁同步风电机组的分频集电系统拓扑结构,建立了适用于小干扰稳定分析的风电系统的数学模型;其次,通过辨识振荡模态并分析模态参与因子确定了影响系统振荡的主控因素,通过绘制根轨迹分析了主控因素参数变化对系统振荡的影响,并发现系统振荡受发电机电感、电阻和直流电容参数的影响最大;最后,通过时域仿真验证了研究结论的正确性。

基于VSG的永磁风力发电机高/低电压穿越研究

为解决永磁风力发电机在高/低电压穿越期间并网点电压和频率波动问题,提出采用虚拟同步发电机(VSG)控制网侧变流器,提高永磁风力发电系统惯性和阻尼,使其在电压穿越期间支撑并网点电压和频率的恢复。通过VSG的有功-频率调节作用,根据系统频率变化量,调节网侧变流器有功功率输出能力,在转动惯量和阻尼系数的作用下实现对频率波动的抑制;调节VSG的无功功率指令实现对虚拟电动势的调节,使其在电压穿越期间为电网提供动态无功支撑,对并网点电压进行调节。并有效抑制连续高/低电压穿越期间系统功率、频率持续性波动,提高系统在连续高/低电压穿越期间的并网稳定性。最后,通过系统仿真验证所提控制策略的有效性。

海上半直驱永磁风力发电机电磁设计与温度场分析

以海上16 MW半直驱永磁风力发电机作为研究对象,基于有限元分析方法针对不等气隙条件下电磁特性、冷却结构设计及温度场仿真展开研究,结果表明优化后的电机能够合理地降低电机损耗,提高电磁性能,水套冷却和空水冷却相结合的冷却方式散热效果良好。通过型式试验,验证了电机设计的合理性。该电机的设计对海上永磁风力发电机大型化的发展发挥了重要作用。

齿轮箱油对发电机影响研究及应用

中速永磁风力发电机组的发电机与齿轮箱高度集成,共用高速轴和端盖。若端盖密封失效会导致油液、油雾进入发电机内部。由于端盖密封的寿命未经过长期老化验证,因此亟需研究油液、油雾对发电机绕组绝缘和防腐等功能的影响。然而,齿轮箱漏油程度等环境工况无法量化,故在研究过程中通过常规试验项目提高试验严苛等级,提出了“高温长时油膜+高温长时浸油”的发电机绝缘及防腐耐油测试方法,完成了发电机绝缘的系统级防腐体系的油雾耐受性试验,为发电机的可靠性设计提供了重要依据。

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。

一种爬壁机器人的移动方案设计

本文研究了一种可以在风机塔筒外部爬行的自走式清刷机器人。首先,根据爬壁机器人的功能需求确定了项目的性能指标。然后,借助MATLAB计算推导出铰链夹角、底盘高度与塔身直径之间的关系,确定了悬架设计方案。最后通过ANSYS软件对永磁吸附装置进行有限元分析,确定了适宜本设计的永磁体材料、尺寸、轭铁厚度等参数。

Three-phase AC-DC Converter for Direct-drive PMSG-based Wind Energy Conversion System

In this paper,a wind energy conversion system(WECS)is presented for the electrification of rural areas with wind energy availability.A three-phase AC-DC converter based on a bridgeless Cuk converter is used for power extraction from the permanent magnet synchronous generator(PMSG).The bridgeless topology enables the elimination of the front-end diode bridge rectifier(DBR).Moreover,the converter has fewer components,simple control,and high efficiency,making it suitable for a small-scale WECS.A squirrel cage induction motor(SCIM)is used to emulate a MOD-2 wind turbine to implement the PMSG-based WECS.A direct-drive eight-pole PMSG is used in this study;thus,a low-input-voltage system is designed.The converter is designed to operate in the discontinuous inductor current mode(DICM)for inherent power factor correction(PFC)and the maximum power point tracking(MPPT)is achieved through the tip-speed ratio(TSR)following.The performance of the developed system is analyzed through simulation,and a 500 W hardware prototype is developed and tested in different wind speed conditions.

基于变流器控制的永磁风电机组低电压穿越控制策略

针对永磁风电机组低电压穿越(low voltage ride-through,LVRT)采用改变背靠背变流器控制策略的方法时,存在未考虑因转子转速越限导致机组发生超速脱网的问题,提出了基于变流器控制的LVRT控制策略。基于转子运动方程,推导了能够抑制机组转子转速越限的机侧变流器有功功率整定计算公式,设计了可降低卸荷电阻使用率的卸荷电阻投切方法,仿真结果验证了该策略的有效性。

Design and Implementation of Bi-Directional DC-DC Converter for Wind Energy System

This paper proposes a design and implementation of the bi-directional DC-DC converter for Wind Energy Conversion System. The proposed project consists of boost DC/DC converter, bi-directional DC/DC converter (BDC), permanent magnet DC generator and batteries. A DC-DC boost converter is interface with proposed wind system to step up the initial generator voltage and maintain constant output voltage. The fluctuation nature of wind makes them unsuitable for standalone operation. To overcome the drawbacks an energy storage device is used in the proposed system to compensate the fluctuations and to maintain a smooth and continuous power flow in all operating modes to load. Bi-directional DC-DC converter (BDC) is capable of transforming energy between two DC buses. It can operate as a boost converter which supplies energy to the load when the wind generator output power is greater than the required load power. It also operates in buck mode which charges from DC bus when output power is less than the required load power. The proposed converter reduces the component losses and increases the performance of the overall system. The complete system is implemented in MATLAB/SIMULINK and verified with hardware.

Modeling and control of a permanent magnet synchronous generator dedicated to standalone wind energy conversion system

为可更新的精力的使用的兴趣增加了，因为环境问题的增加的担心。在可更新的精力之中，风精力现在广泛地被使用。风汽轮机基于有一个创伤转子的一个异步的发电机介绍要求戒指和扫帚的一个系统的不方便，推断维护的重要费用并且一更多样地。限制这些不方便，某些制造商与一些与汽轮机直接联合的杆的大数字基于同步机器开发了风汽轮机，避免使用更多样地。如果生成器与永久磁铁被装备，戒指和扫帚的系统被消除。永久磁铁的控制同步生成器(PMSG ) 能与控制的各种各样的技术的实现被影响。这份报纸基于 PMSG 主要基于力量生产系统的控制策略论述了一条新途径。事实上，模仿 Matlab 链的一个数学模型与控制技术的介绍被建立，例如到控制的转矩( DTC )的直接控制负担方面变换器(最低有效字符)，汽轮机和DC公共汽车电压的速度的控制由 PI 管理者保证了。到修正者的性能使用了的表演，系统的一些模拟结果被介绍并且分析。