交流开关磁阻发电机的稳态分析及仿真

提出只需在开关磁阻发电机每相定子绕组并联一个交流电容,形成交流开关磁阻发电机( AC SRG),周期性变化的相电感和电容构成LC参量振荡电路,输出交流电压,不需要功率变换器和位置传感器,磁链能用于两个象限;提出其电路模型和数学模型,分析稳定运行条件和机电能量转换过程,给出变速运行的电容值选定方法;建立仿真模型,仿真结果表明该系统能稳定运行,静动态性能较好,验证了AC SRG的可行性和简单性,适合用于偏僻地区的小型风力发电.     

基于三电平功率变换器提高SRG输出功率

分析了开关磁阻发电机(SRG)的发电运行条件和提高输出功率的关键因素,提出用三电平功率变换器加入一个中间惯性状态,增大励磁电流和发电续流区的平均电流,以提高SRG的输出功率;采用SRG电压反馈控制系统,保证同时获得良好的恒定输出电压品质;提出三电平功率变换器的开关控制策略,建立基于自励发电模式和电流斩波控制模式的SRG电压反馈控制系统仿真模型;仿真研究验证了该方法的可行性和有效性.     

变速恒频风力发电系统及其控制技术研究

为了最大限度地利用风能,风力发电系统应采用变速恒频控制策略。分析了鼠笼异步发电系统、双馈发电系统、无刷双馈发电等变速恒频风力发电系统的原理、性能及特点,通过对比各种风力发电机和各种控制方法的优缺点,对未来风力发电机和风力发电控制技术的发展趋势做了展望: 风力发电机大型化;采用变桨距和变速恒频技术;风力发电机采用直接驱动;采用智能化控制等。     

开关磁阻发电机他励模式下的简易功率变换器控制

针对不对称半桥功率变换器的主开关器件较多的缺点,提出开关磁阻发电机(SRG)他励模式下的简易功率变换器控制。给出并分析简易功率变换器的主电路结构,建立相应的SRG他励发电数学模型,分析能量转换和发电效率,与不对称半桥功率变换器相比,其每相只需一个主开关器件,降低了成本,能在SRG停转时对负载供电,且在一定条件下能提高发电效率。对基于简易功率变换器的SRG他励发电系统进行了仿真和实验,仿真和实验结果表明系统能够稳定运行,发电质量好,验证了该方法的可行性和简单性,具有一定工程应用价值。     

变速直驱开关磁阻风力发电系统的控制与实现

对开关磁阻发电机的运行原理和风轮机的功率输出特性进行了分析,提出了一种不依赖风轮机运行参数即可实现最大风能跟踪的控制方法。使用MATLAB/SIMULINK构建了系统模型,进行了仿真,并在试验室中进行了验证。设计了一套10kW开关磁阻风力发电系统并应用到现场,实现了变速直驱发电,给出了部分现场数据,证明直驱式开关磁阻风力发电是可行的。     

采用磁场调制发电机的变速恒频风力发电系统

本文对恒速恒频和变速恒频两种风力发电系统进行了比较,阐述了磁场调制发电机系统的线路和工作原理,介绍了采用这种发电机的风力发电系统的运行和控制问题,并讨论了4千瓦样机在大型风洞中和6米达里厄型风轮机配套运行的实验结果。     

双馈电机变速恒频风力发电系统研究

结合双馈发电机特性,分析了双馈电机变速恒频风力发电系统的工作原理。重点介绍了变速恒频运行方式下双PWM变换器的原理和定子磁场矢量控制系统的设计,并提出了以ARM作为核心控制器的控制系统结构,对系统矢量控制部分进行了仿真实验。     

无刷双馈风力发电系统双空间矢量调制矩阵变换器励磁控制

矩阵变换器具有低频性能好、功率因数可调节、四象限运行等特点,以矩阵变换器为无刷双馈风力发电机的励磁控制器,可建立交流励磁变速恒频风力发电系统。采用双空间间接矢量控制策略控制矩阵变换器输出电流的幅值、频率、相位,从而调节发电机控制绕组电流的幅值、频率、相位,实现无刷双馈风力发电系统的变速恒频运行及功率因数控制。采用C语言编写数字信号处理器控制系统程序,实现双空间间接矢量调制策略,复杂可编程逻辑器件实现四步换流和产生双向开关矩阵控制信号。通过实际风力发电机组平台进行了相关试验,结果验证了控制方案的有效性。     

基于S函数的并网型交流励磁双馈电机风力发电系统研究

介绍了交流励磁变速恒频双馈电机的运行原理,推导了双馈电机在发电机惯例下的数学模型,采用S函数实现了双馈电机动态系统的状态方程数学描述,并使其和Simulink解法器进行交互.变速恒频双馈电机风力发电是一个受并网前后发电机运行状况影响的暂态过程,利用S函数编写双馈电机的仿真程序,建立了空载运行和发电运行的变速恒频双馈电机风力发电子系统模型,在仿真过程中可对双馈电机进行精确控制,然后对其进行了系统整合,最后对系统在不同工况下的响应特性进行了仿真研究.变速恒频双馈电机风力发电系统的仿真与理论分析高度一致,同时,仿真结果验证了系统对转速突变和电网电压跌落工况的有效性.     

基于Buck变换器的开关磁阻发电机新型励磁模式

提出了基于Buck变换器的开关磁阻发电机(SRG)新型励磁模式。给出并分析新型模式的功率变换器主电路,每相桥臂只需1个主开关器件和1个续流二极管;直流侧电容两端加一个Buck变换器,SRG的输出电压经Buck变换器降压后作为励磁电压,将输出的部分能量回馈到励磁电容,实现励磁。该励磁模式无需外部励磁电源,改变占空比D或通过Buck变换器闭环控制可独立调节励磁电压,且D>0.5时有利于提高输出功率。建立SRG新型励磁发电系统仿真模型,仿真结果表明系统能稳定运行,励磁电压独立可控,发电质量较好,验证了所提出的新型励磁模式的可行性和优越性。     

Approach for performance optimization of switched reluctance generator in variable-speed wind generation system

In this paper, algorithms are proposed to get optimal parameters of a switched reluctance generator (SRG) when applied in variable speed wind generation systems. The driver’s parameters affect power generated, torque ripples, iron losses, and electric losses. Therefore, the optimal values of the drive activation must be defined for SRG’s operation in a wide speed range. Thus, knowing the operating points of the wind turbine (speed and power), algorithms that perform dynamic simulations of the operation at low and high speed were developed. Driver’s parameters of the SRG are obtained through cost functions, which are defined such that the balance between torque ripples, iron losses, and electric losses are maintained. With simulations results, the cost functions were minimized to get SRG’s optimal firing angles according to the operating speed. Simulation and experimental tests were performed emulating a wind turbine system. The results confirmed the efficiency of the methodology proposed in this paper.     

Control of a switched reluctance generator for variable-speed wind energy applications

This paper presents a novel control system for the operation of a switched reluctance generator (SRG) driven by a variable speed wind turbine. The SRG is controlled to drive a wind energy conversion system (WECS) to the point of maximum aerodynamic efficiency using closed loop control of the power output. In the medium and low speed range, the SRG phase current is regulated using pulsewidth-modulation (PWM) control of the magnetizing voltage. For high speeds the generator is controlled using a single pulse mode. In order to interface the SRG to the grid (or ac load) a voltage-source PWM inverter is used. A 2.5-kW experimental prototype has been constructed. Wind turbine characteristics are emulated using a cage induction machine drive. The performance of the system has been tested over the whole speed range using wind profiles and power impacts. Experimental results are presented confirming the system performance.     

Design optimization and site matching of direct-drive permanent magnet wind power generator systems

This paper investigates the possible site matching of the direct-drive wind turbine concepts based on the electromagnetic design optimization of permanent magnet (PM) generator systems. Firstly, the analytical models of a three-phase radial-flux PM generator with a back-to-back power converter are presented. The optimum design models of direct-drive PM wind generation system are developed with an improved genetic algorithm, and a 500-kW direct-drive PM generator for the minimal generator active material cost is compared to demonstrate the effectiveness of the design optimization. Forty-five PM generator systems, the combinations of five rated rotor speeds in the range of 10–30 rpm and nine power ratings from 100 kW to 10 MW, are optimally designed, respectively. The optimum results are compared graphically in terms of the generator design indexes. Next, according to the design principle of the maximum wind energy capture, the rotor diameter and the rated wind speed of a direct-drive wind turbine with the optimum PM generator are determined. The annual energy output (AEO) is also presented using the Weibull density function. Finally, the maximum AEO per cost (AEOPC) of the optimized wind generator systems is evaluated at eight potential sites with annual mean wind speeds in the range of 3–10 m/s, respectively. These results have shown the suitable designs for the optimum site matching of the investigated PM generator systems.     

开关磁阻风电系统最大风能追踪控制

根据风力机的特性，探讨了追踪、捕获最大风能的方法；针对开关磁阻电机的特点，提出了开关磁阻电机变速恒频风力发电系统最大风能追踪的控制方案；详细的仿真研究验证了该控制策略的正确性和可行性。     

基于直流电机的风力机模拟技术研究

分析了风力机的运行原理,建立了风力机模型,制定了简单有效的转速、转矩控制模拟方案,搭建了基于DSP的直流电机风力机模拟平台,应用LabWindows/CVI开发了上位机界面。该风力机模拟系统应用于并网型变速恒频交流励磁双馈风力发电系统,实现了模拟风力机在不同风速、转速下的运行状态,满足了双馈发电机在同步、超同步、亚同步状态下运行以及进行风电系统最大风能追踪等方面研发的需要,可方便用于实验室条件下风电技术的研究。     

基于运行数据的风电机组转矩控制性能评估

风电机组的性能评估方法具有多样性及复杂性的特点,基于风电场SCADA系统中采集的大量风电机组运行数据,对风电机组转矩控制的性能评估方法进行了研究。在深入分析风电机组中发电机转速与发电机转矩关系的基础上,提出了风电机组在最佳风能利用系数Cp(max)跟踪区内的转矩优化控制的性能评估方法。通过筛选有效数据,拟合计算出风电机组的实际运行转矩增益系数;再通过与理论最优转矩增益系数进行对比,找出风能捕获能力较弱的风电机组,进而采取措施提高其发电量。通过软件仿真及案例分析表明,该方法在不增加设备及成本的情况下,可有效识别因转矩控制的性能差而影响发电量的风电机组,以便及时进行控制策略调校,维护风电场的利益。     

Autonomous renewable energy conversion system

This paper briefly reviews the need for renewable power generation and describes a medium-power Autonomous Renewable Energy Conversion System (ARECS), integrating conversion of wind and solar energy sources. The objectives of the paper are to extract maximum power from the proposed wind energy conversion scheme and to transfer this power and the power derived by the photovoltaic system in a high efficiency way to a local isolated load. The wind energy conversion operates at variable shaft speed yielding an improved annual energy production over constant speed systems. An induction generator (IG) has been used because of its reduced cost, robustness, absence of separate DC source for excitation, easier dismounting and maintenance. The maximum energy transfer of the wind energy is assured by a simple and reliable control strategy adjusting the stator frequency of the IG so that the power drawn is equal to the peak power production of the wind turbine at any wind speed. The presented control strategy also provides an optimal efficiency operation of the IG by applying a quadratic dependence between the IG terminal voltage and frequency V∼f². For improving the total system efficiency, high efficiency converters have been designed and implemented. The modular principle of the proposed DC/DC conversion provides the possibility for modifying the system structure depending on different conditions. The configuration of the presented ARECS and the implementation of the proposed control algorithm for optimal power transfer are fully discussed. The stability and dynamic performance as well as the different operation modes of the proposed control and the operation of the converters are illustrated and verified on an experimental prototype.     

全功率变流风力发电系统电压跌落响应特性研究

随着风电机组数量的增加,电网故障时风机的动态响应越来越重要。利用madab／simulink,在建立采用永磁同步电机的直接驱动型变速恒频风电系统模型的基础上,分析了电网电压分别跌落30％-10s、50％-0．58s,85％-0．2s时永磁直驱式风电系统的动态响应。并搭建了实验系统,进行了实验验证。结果表明,直驱式风电系统在3种典型跌落情况下,具有良好的低压度过能力。     

Autonomous BDFIG-wind generator with torque and pitch control for maximum efficiency in a water pumping system

This paper presents and analyzes the operation strategy for an autonomous wind energy conversion system oriented to water pumping. It consists of a wind turbine with a Brushless Doubly-Fed Induction Generator (BDFIG), electrically coupled with a squirrel cage induction machine moving a centrifugal type water pump. Because of no brushes and slip rings, the BDFIG is suitable for autonomous systems, which often work in hard conditions. Additionally, the power flow on the BDFIG principal stator could be driven from a fractional power converter connected on the auxiliary stator winding. This Turbine-BDFIG and Motor-Pump configuration provides a high robustness and reliability, reducing the operational and maintenance costs. The operation strategy proposes, for wind speeds smaller than the rated, to maximize the volume of water pumped based on the optimization of the wind energy capture. To do that, a sliding mode control tracks the optimal turbine torque by means of a torque control. Meanwhile, for wind speeds greater than the rated, a pitch control keeps the water pump within the safe operation area by adjusting the speed and power of the turbine in their rated values. To assess and corroborate the proposed strategy, simulations with different wind profiles are made.     

Optimization of Multibrid Permanent-Magnet Wind Generator Systems

This paper investigates the cost-effective ranges of gearbox ratios and power ratings of multibrid permanent-magnet (PM) wind generator systems by using a design optimization method. First, the analytical model of a multibrid wind turbine concept consisting of a single-stage gearbox and a three-phase radial-flux PM synchronous generator with a back-to-back power converter is presented. The design optimization is adopted with a genetic algorithm for minimizing generator system cost. To demonstrate the effectiveness of the developed electromagnetic design model, the optimization results of a 500-kW direct-drive PM generator and a 1.5-MW multibrid PM generator with various gear ratios are, respectively, compared with those from other methods. Then, the optimal design approach is further employed for a range from 750 kW up to 10 MW. The optimization results of PM generator systems including direct-drive and multibrid wind turbine configurations are obtained, and the suitable ranges of gear ratios for different power ratings are investigated. Finally, the detailed comparisons of the most cost-effective multibrid PM generator system and the optimized direct-drive PM generator system are also presented and discussed. The comparative results have shown that the multibrid wind turbine concept appears more cost-effective than the direct-drive concept.