基于储能技术的直驱式风力发电机无功控制

风电系统中的电压源型变流器储能系统得到广泛应用,文章分析以超级电容器为储能元件,采用双向DC/DC变流器控制的储能系统对直驱式风机的影响,提出一种基于超级电容器储能的直驱式风力发电机无功控制策略。通过储能系统和风机变流器协调控制,维持直流电压恒定,提高直驱式风电系统的无功输出能力。最后基于3种无功控制方案的算例进行仿真,仿真结果验证了文章控制策略的可行性和有效性。     

采用耦合电抗器的兆瓦级永磁直驱风电变流器仿真研究

提出一种采用耦合电抗器的独立直流母线型永磁直驱风电变流器,分析其去耦等效电路和高阻抗环流路径,阐明耦合电抗器抑制环流的根本机理,并分别建立机侧变换器和网侧变换器的数学模型,根据所得模型分别设计控制策略,实现了永磁直驱风电变流器的并联运行,抑制了环流,解决了环流引起的不均流、波形畸变等问题,提高了系统的可靠性和效率。最后,对一组采用耦合电抗器的1.5 MW永磁直驱风电变流器进行了仿真验证,结果证明上述分析及控制策略的正确性。     

PMSG发电系统不平衡电网下网侧变流器控制研究

文章通过对电网不平衡情况下风力发电系统的分析,提出了以抑制负序不平衡电流为主要控制方法的网侧变流器控制策略。为维持不平衡下直流母线电压的稳定,提出电流微分前馈的控制方法,结合以上两点控制方法设计出电网不平衡下永磁直驱风力发电系统网侧变流器综合控制策略,该控制方法结构相对简单、有效,并具有一定的低电压穿越能力。最后在Matlab/Simulink下仿真验证了3 MW永磁直驱风机控制的有效性。     

基于永磁同步发电机的直驱风电双脉宽调制变流器的研制

阐述了永磁直驱风电系统背靠背双脉宽调制(PWM)全功率变流器的电路结构和控制原理,利用Matlab软件建立了该系统的仿真模型,对其稳态和动态性能进行了分析.并构建了永磁直驱风电试验平台和双PWM变流器系统.结果表明:采用双PWM变流器作为永磁直驱风电系统的变流器,可以实现对永磁同步发电机(PMSG)的优良控制,并向电网输送优质的电能.     

含超级电容器储能的永磁直驱风电系统低电压运行与控制

为实现电网不平衡条件下直驱风电系统低电压穿越,通过研究含超级电容器储能单元的系统运行特性,建立超级电容器储能单元小信号模型,实现精准的充放电控制,确保系统安全稳定运行。提出风电系统中储能容量的确定方法,研究适合于该系统的低电压运行的控制策略,包括限制机侧变流器有功输出以及调整网侧变流器有功无功分配,为电网提供无功支撑。提出新的频率自适应正序电压分量检测法,为变流器运行提供精准快速的响应信号,提高系统鲁棒性。通过仿真验证含超级电容器储能的直驱风机系统及其控制策略的可行性。     

稳定风电输出功率的控制策略研究

为稳定风电系统输出功率,提出一种在变流器的直流侧加入超级电容器(EDLC)储能的新拓扑结构,通过分析全功率双脉宽调制交-直-交变流器的控制策略,基于永磁直驱风电机组与电网连接的拓扑结构,提出超级电容器储能系统稳定风电系统输出功率的控制策略和输出功率的解耦控制方法,分析了风电系统输出功率初始值和超级电容器容量对输出功率稳定性的影响,并针对典型风速变化给出了输出功率初始值与超级电容器容量的整定范围。     

永磁直驱风力机低电压运行储能容量取值研究

针对永磁直驱风力机低电压运行时存在的直流侧过电压问题,建立了运用超级电容器储能来解决该问题的方案,提出了超级电容器储能容量取值方法。对故障前后系统能量变化进行分析设计了储能系统充放电控制策略,结合超级电容器等效模型进行数学推导得出储能容量计算表达式。通过模拟不同深度电压跌落故障进行仿真计算,分别得出所需超级电容器储能容量。最后对比储能投入前后直流侧电压变化证明了所提出的储能容量计算方法的正确性以及储能系统控制策略的有效性。     

基于两级全钒液流电池的风电储能系统的功率优化分配控制

为更好地利用储能系统平抑风电功率波动,采用了两级全钒液流电池(VRB)储能的功率优化分配及控制策略。基于直驱型永磁同步风电系统的工作原理及系统变流器的控制策略,建立了全钒液流电池等效电路模型,采用基于VRB组荷电状态(SOC)的双模式切换的双闭环控制策略,通过比较每级电池组荷电状态值确定优选目标,以VRB组最大充放电功率为电池组安全充放电的约束条件,提出两级VRB组的功率优化分配控制策略,利用Matlab/Simulink仿真平台,在变风速条件下对不同荷电状态的两级VRB储能系统平抑风电功率波动进行仿真,并与功率平均分配策略作对比。结果表明,两级VRB储能系统功率优化分配控制策略能有效平抑风电机组功率波动,同时,还确保了电池组工作于安全运行区域,有效地减少了VRB组的充放电次数,延长了电池组的寿命。     

风光储微网系统孤岛运行控制策略研究

文章建立了基于光伏发电系统、永磁同步风力发电系统以及混合储能系统的微网系统,主要对低压微网孤岛运行控制策略进行研究。针对传统单一主电源控制存在的缺陷,设计了由超级电容和蓄电池组成的混合储能系统作为主电源,采用改进V/F控制策略,为微网系统提供电压和频率支撑,同时在微网系统频率波动时实现功率的快速跟踪;风力发电系统和光伏发电系统作为从电源,采用按最大功率跟踪输出的PQ控制策略。基于PSCAD/EMTDC仿真平台建立了微网系统仿真模型并对不同运行工况进行仿真实验,仿真结果表明了该控制策略的有效性,同时微网孤岛运行的可靠性和稳定性得到了提高。     

大容量永磁同步风电机组系统谐振分析与试验研究

风机变流器是变速恒频风电机组的核心部件,变流器电网侧LC/LCL滤波器在保证良好并网特性同时也带来了谐振问题。针对该问题,文章基于风机变流器网侧滤波器动态特性分析,揭示了风电机组谐振机理,分析了系统阻尼对谐振的影响。在Matlab/Simulink中建立了2.0 MW直驱型永磁同步发电机组系统仿真模型,实现了风电机组谐振的全过程仿真。首次在2.0MW永磁直驱风电机组上进行了机组谐振现场试验,仿真与现场试验证明了理论分析的正确性。在此基础上,提出了风电机组谐振消除与抑制方法,对实际运行风电机组谐振改造和变流器设计具有现实的指导意义。     

Coordinated control strategy for a PV-storage grid-connected system based on a virtual synchronous generator

Due to the characteristics of intermittent photovoltaic power generation and power fluctuations in distributed photovoltaic power generation, photovoltaic grid-connected systems are usually equipped with energy storage units. Most of the structures combined with energy storage are used as the DC side. At the same time, virtual synchronous generators have been widely used in distributed power generation due to their inertial damping and frequency and voltage regulation. For the PV-storage grid-connected system based on virtual synchronous generators, the existing control strategy has unclear function allocation, fluctuations in photovoltaic inverter output power, and high requirements for coordinated control of PV arrays, energy storage units, and photovoltaic inverters, which make the control strategy more complicated. In order to solve the above problems, a control strategy for PV-storage grid-connected system based on a virtual synchronous generator is proposed. In this strategy, the energy storage unit implements maximum power point tracking, and the photovoltaic inverter implements a virtual synchronous generator algorithm, so that the functions implemented by each part of the system are clear, which reduces the requirements for coordinated control. At the same time, the smooth power command is used to suppress the fluctuation of the output power of the photovoltaic inverter. The simulation validates the effectiveness of the proposed method from three aspects: grid-connected operating conditions, frequency-modulated operating conditions, and illumination sudden-drop operating condition. Compared with the existing control strategies, the proposed method simplifies the control strategies and stabilizes the photovoltaic inverter fluctuation in the output power of the inverter.     

A review of power converter topologies for wind generators

Wind energy conversion systems have become a focal point in the research of renewable energy sources. This is in no small part due to the rapid advances in the size of wind generators as well as the development of power electronics and their applicability in wind energy extraction. This paper provides a comprehensive review of past and present converter topologies applicable to permanent magnet generators, induction generators, synchronous generators and doubly fed induction generators. The many different generator–converter combinations are compared on the basis of topology, cost, efficiency, power consumption and control complexity. The features of each generator–converter configuration are considered in the context of wind turbine systems.     

Introduction to motors and controllers of flywheel energy storage systems

简述了飞轮储能系统的基本组成,介绍了飞轮储能系统常用的永磁无刷直流电机、永磁同步电机、感应电机和开关磁阻电机的工作原理和特点,讨论了四种电机的控制策略,分析了各种控制策略的优缺点及其应用。     

Control of permanent-magnet generators applied to variable-speed wind-energy systems connected to the grid

Wind energy is a prominent area of application of variable-speed generators operating on the constant grid frequency. This paper describes the operation and control of one of these variable-speed wind generators: the direct driven permanent magnet synchronous generator (PMSG). This generator is connected to the power network by means of a fully controlled frequency converter, which consists of a pulsewidth-modulation (PWM) rectifier, an intermediate dc circuit, and a PWM inverter. The generator is controlled to obtain maximum power from the incident wind with maximum efficiency under different load conditions. Vector control of the grid-side inverter allows power factor regulation of the windmill. This paper shows the dynamic performance of the complete system. Different experimental tests in a 3-kW prototype have been carried out to verify the benefits of the proposed system.     

Energy storage-based power buffering control for photovoltaic power generation system

光伏发电系统输出的最大功率随外界环境变化而波动,无法满足负荷的供电需求,针对该问题,建立了基于储能系统的光伏发电系统结构,介绍了光伏发电系统运行原理,分析了系统功率与直流母线电压的关系,设计了无源式储能系统和有源式储能系统对功率进行缓冲以满足控制目标.仿真结果表明,有源式储能系统较无源式储能系统有更好的功率调节作用,通过双向DC-DC变换器的储放能量自动切换控制,使得光伏发电系统输出的功率与负荷需求功率良好匹配,直流电压稳定.     

计及变流器影响的直驱式永磁同步发电机二阶自抗扰控制

研究基于新型自抗扰技术的直驱式永磁同步发电机电气控制系统。考虑变流器对控制系统输出电压的影响,建立发电机组的数学模型,以此为基础设计二阶自抗扰控制器,对设计的扩张状态观测器和控制器的收敛性进行分析并给出控制参数配置方法。通过仿真对所提控制系统的可行性及控制性能进行定量分析,结果表明,该控制系统能够快速稳定的控制发电机组的运行过程,且相比传统的矢量控制及一阶自抗扰控制具有更好的动态性能及鲁棒性能。     

Control of a grid-connected direct-drive wind energy conversion system

This paper investigates the current control for a grid-connected direct-drive wind energy conversion system (DDWECS) with a permanent magnet synchronous generator (PMSG), which utilizes a back-to-back pulse width modulation (PWM) converter. For the machine-side, the controller adopts a current vector control method based on the rotating reference frame (RRF) and the maximum power extraction (MPE) is realised through the tip speed ratio (TSR) method. For the grid-side, a novel controller is proposed for the first time to be successfully used for the DDWECS, which combining a proportional complex integral (PCI) current inner loop based on stationary reference frame (SRF) for regulating the grid-side current with a dc voltage outer loop for stabilizing the dc bus voltage and compare with the proportional resonant (PR) controller. A system simulation model is established by using the Matlab/Simulink to simulate the performance of the DDWECS and a prototype system has been build and tested to verify the validity of the developed control methods for both machine-side and grid-side and the excellent performance of the DDWECS.     

A novel direct-drive ocean wave energy extraction concept with contact-less force transmission system

This paper describes the design and testing of a new rotary direct-drive ocean wave energy extraction system. The device employs a contact-less force transmission system (CFTS) to couple a float to the power take-off (PTO) mechanism made up of a ball screw, unidirectional clutch and a permanent magnet generator. Comprehensive simulation, design and testing of both the force transmission system and the ocean energy extraction system are presented along with preliminary wave flume test results of the buoy in irregular waves.     

基于Matlab/Simulink的永磁直驱风力发电机组建模和仿真研究

以永磁直驱风力发电机组为研究对象,建立了包括风力机、传动部分、永磁直驱发电机、矢量控制策略、最大风能捕获策略的整体数学模型;应用Matlab/Simulink工具,以建立的数学模型为基础搭建了永磁直驱风力发电机组仿真模型,并以两次阶跃风速为例对所建模型并网后运行特性进行了仿真研究。实现了永磁直驱风力发电机组的最大风能捕获和功率解耦控制,仿真结果表明,永磁直驱风力发电机组具有良好的运行特性,同时验证了所建模型的正确性和有效性。