永磁直驱风力发电系统MPPT控制的研究

文章首先介绍了风力机模型。然后介绍了一种改进型的变步长爬山算法,通过该算法改变直驱风力发电系统三重交错并联Boost变换电路的占空比,从而实现最大功率跟踪,获取最大风能。最后,利用MATLAB/SIMULINK建立直驱永磁风力发电系统仿真模型并进行研究。试验结果表明,改进型变步长爬山算法比传统爬山算法能更快跟踪最大功率点,控制系统具有较好的控制精度和稳定性。     

双级式光伏并网变换器的控制策略研究

文章针对双级式光伏并网前级Boost变换器,提出了一种具有功率、电压双闭环结构和基于梯度信息的变步长MPPT控制策略,它直接从光伏阵列的功率-电压特性出发,依据梯度信息直接给出最大功率点电压,进而通过电压闭环实现自动寻优,快速实现最大功率跟踪控制。针对后级含有LCL滤波器的逆变器,基于常规矢量控制技术,引入了有源阻尼控制中的电容电流反馈技术,给出了一种含有LCL滤波器的逆变器有源阻尼功率解耦控制策略,能够实现直流侧电压恒定和单位功率因数的并网控制,且在不增加系统损耗的情况下有效抑制系统谐振。建立了10 kW双级式光伏并网系统仿真模型,仿真结果表明,系统能够快速跟踪光强变化,实现MPPT控制及单位功率因数并网控制,具有良好的动态调节性能和静态特性。     

新型MPPT算法在两级式光伏并网系统中的应用

以光伏发电系统为研究对象,分别结合相应的控制算法建立了一种带有最大功率点跟踪(MPPT)功能的光伏并网系统,并利用Matlab软件进行了仿真。仿真结果表明,前级Boost电路基于新型算法——变步长扰动观察法实现了最大功率点跟踪的功能;后级逆变电路采用电压外环、电流内环的双闭环控制方式,使逆变器的输出能准确、快速地跟踪电网电压变化,并与电网电压保持同频、同相。该系统的输出为纹波较少的正弦波形,功率因数接近于1,可满足光伏并网对逆变器的要求。     

并网中小型风电系统最大功率跟踪控制

针对目前中小型风力发电系统发电效率低,提出了一种新型拓扑结构,即机侧采用三相PWM整流器,网侧采用单相PWM逆变器。在对永磁同步发电机数学模型和风力机最佳输出功率进行分析的基础上,采用转子磁链定向控制技术,实现对发电机输出的有功功率的控制,进而实现对风力发电机最大功率的跟踪控制;同时,在单相系统中引入"虚拟电路",使网侧单相变流电路参数可以转化到旋转坐标系下,实现无静差控制。通过仿真试验验证了控制策略的可行性。     

中小型风力发电系统单相并网逆变器控制策略研究

介绍了适用于中小型风力发电系统并网的单相逆变器主电路拓扑及其典型控制策略;针对传统PI控制器和新型PR控制器进行了详细的理论分析和比较。利用Matlab/Simulink搭建了风力发电系统单相并网逆变器仿真模型,分别对PI控制器和准PR控制器进行了仿真研究。仿真结果显示,新型准PR控制器具有更好的稳态特性、跟踪特性和更强的抗电网扰动能力。该控制策略对于中小型风力发电系统并网逆变器的实际应用具有重要意义。     

离网型风力发电测试及实验系统一体化研究

利用LabVIEW软件及相关配套硬件设备,开发了一套实用的基于虚拟仪器技术的离网型风力发电性能测试系统。为简化离网型风力发电模拟系统结构、降低成本,设计了包含变频器、异步电动机、永磁同步发电机、二极管整流桥堆、升压斩波器、铅酸蓄电池、全桥逆变器和负载的小型风力发电实验系统。针对系统能量转换的核心——蓄电池,采用HC16F877单片机和Boost斩波电路实现其智能充放电控制;对决定系统性能的逆变器进行了理论分析和基于MATLAB的计算机仿真。所提方案正确可行,对离网型风力发电系统的研究开发具有工程指导意义。     

基于DSPIC30F6010A双闭环控制的并网逆变器的研究与实践

光伏并网发电是光伏发电应用发展的趋势.并网逆变器是光伏并网发电系统核心部件之一,基于DSPIC30F6010A芯片控制的并网系统,利用DSP丰富的外围电路和强大的功能实现并网系统的所有工作、控制和相应的保护功能等.针对输出电流谐波含量大的特点,提出了基于同步PI内环控制和直流电压前馈外环控制的双闭环电流控制思路,并网逆变器采用前级DC/DC的boost升压结构电路,减少系统体积和重量;后级DC/AC逆变器采用全桥逆变电路;且具有最大功率跟踪和反孤岛效应等功能.仿真和实验证明:利用提出的算法,可有效减少并网电流的谐波,光伏并网系统具有可靠性强,工作效率高,稳定性好等优点.     

基于比例多谐振控制的直驱永磁风力发电系统谐波抑制研究

直驱永磁同步发电机受变流器开关频率限制及电网电压畸变的影响,并网电流常含有大量且难以消除的低频谐波。文章基于双PWM并网变流器建立永磁同步风力发电系统仿真模型;提出一种高性能比例多谐振电流环控制器以提高电流环的谐波抑制能力和改善跟踪控制性能,并对基于传统PI控制及比例多谐振控制的永磁风力发电系统进行了对比。仿真和实验结果验证了风力发电控制系统模型的正确性,以及比例多谐振控制器谐波抑制的优越性。     

基于BOOST变换器的小型风力机并网逆变控制系统设计

概述了基于BOOST变换器的小型风力机并网逆变控制系统设计方案。系统由一个H桥并网逆变器和一个BOOST升压斩波电路组成。对并网逆变器采用电流内环和电压外环双环控制,以取得网侧电流的快速跟随性和直流侧电压的抗扰性;对BOOST斩波电路进行功率控制,实现风力发电机的最大功率跟踪。系统采用了根轨迹图解法进行控制器参数设计,并取得了较好的动态控制性能。最后,以1.5kW并网逆变器的试验结果验证了设计的正确性。     

永磁直驱风力发电并网逆变器电流滞环控制

永磁直驱风力发电系统网侧逆变器采用单电流环控制时,其稳定性不足,输出电流谐波含量大、电能质量下降。文章分析了含有LCL滤波并网逆变器的数学模型,提出了瞬时功率外环、电流滞环内环的控制策略。通过仿真结果表明,在该控制策略下,并网系统输出的电流波形较好,谐波含量低,具有良好的动态跟踪响应特点,并满足了风力发电并网的控制要求,有效验证了该控制方法的可靠性和正确性     

Maximum power point tracker of wind energy conversion system

In this paper, a simple control strategy for an optimal extraction of output power from grid connected variable speed wind energy conversion system (WECS) is presented. The system consists of a variable speed wind turbine coupled to a permanent magnet synchronous generator (PMSG) through a gear box, a diode bridge rectifier, a dc-to-dc boost converter and a current controlled voltage source inverter. The maximum power point tracker (MPPT) extracts maximum power from the wind turbine from cut-in to rated wind velocity by sensing only dc link power. The MPPT step and search algorithm in addition to the DC–DC and DC–AC converters PWM controllers are simulated using MATLAB-SIMULINK software. The obtained simulation results show that the objectives of extracting maximum power from the wind and delivering it correctly to the grid are reached.     

并网光伏发电系统暂态特性研究

基于光伏发电系统的物理模型研究,在matlab/simulink中开发了包含光伏阵列模型、光伏阵列的最大功率跟踪（MPPT）模块、DC/DC升压电路和采用电压及电流环控制的逆变系统在内的动态仿真模型,并建立了基于电压型逆变器的暂态数学模型;并通过仿真得到了并网光伏发电系统辐射强度突变和发生短路时的暂态运行特性,为深入研究并网光伏发电系统的暂态特性建立了基础。     

A utility interactive wind energy conversion scheme with anasynchronous DC link using a supplementary control loop

The paper presents modelling, simulation and experimental verification of a utility interactive wind energy conversion scheme with an asynchronous link comprised of a diode bridge rectifier and a line commutated inverter. The control objective is to track and extract maximum power from the wind energy system and transfer this power to the electric utility. This is achieved by controlling the firing delay angle of the inverter. Since the diode bridge rectifier has no control on the DC link voltage, a supplementary control loop is used to limit the voltage within a preset voltage threshold. The proposed scheme for regulating the flow of power through the DC link ensures reduced reactive power burden on the self-excitation capacitor banks and better utilisation of available wind energy, while limiting the DC link voltage within a preset voltage threshold. The simulated results are experimentally verified and found to give good power tracking performance     

Power conversion system for high altitude wind power generation with medium voltage AC transmission

High Altitude Wind Power (HAWP) generating system provides clean energy at low cost and high capacity factor due to reduced size of the turbine and high speed streamlined wind at high altitude. An air-borne wind turbine (AWT) at high altitude extracts kinetic energy from wind using buoyancy provided by the blimp/aerostat. The generated electrical power is then transmitted to the ground based station (without any power conditioning) using the transmission lines (tether). The power conversion system (PCS) for harnessing HAWP is proposed in this paper. The proposed PCS consists of a three-level neutral point clamped (NPC) rectifier, a three-level NPC DC–DC converter followed by a two-level inverter. Modelling, design and control of the PCS are presented and discussed. The PCS provides generation side maximum power-point tracking (MPPT) using sensorless optimal torque control technique. The DC–DC converter provides electrical isolation as well as voltage step-down functions. A modified proportional resonant (PR) control which can selectively eliminate lower order current harmonics of the grid-connected inverter is also presented. The proposed control scheme of the PCS is evaluated through simulation studies using software programs like PSIM and MATLAB. A scaled-down 1 kW laboratory prototype of the complete PCS is designed, built and tested. The experimental test results obtained validate the proposed control scheme for efficient power generation from high altitude wind and interface to the grid/load.     

Development of a comprehensive MPPT for grid‐connected wind turbine driven PMSG

This paper proposes a comprehensive MPPT method by which extraction of maximum power from wind turbine and its subsequent transfer through various power stages and final delivery to the connected grid are realized. In the proposed system, the operation of the wind turbine at its maximum efficiency point is maintained by control of grid‐tied inverter such that the shaft speed of the generator is set to result the desired optimum tip speed ratio of the turbine. The proposed comprehensive MPPT estimates the required DC link voltage for each wind speed using a unified system model, uses a loss factor to account for the system losses, and then controls the inverter to push the WT extracted maximum power into the grid. The comprehensive MPPT is developed and is validated in MATLAB/Simulink platform in a wide range of operating wind speed. The results ascertain that the wind turbine is made to operate at its maximum efficiency point for all wind speeds below the rated one.     

A fuzzy control strategy for power smoothing and grid dynamic response enrichment of a grid‐connected wind energy conversion system

This paper concentrates on the output power smoothing and the grid dynamic response enhancement of a grid‐interactive MW‐class permanent magnet synchronous generator‐based wind energy conversion system (WECS). A simple fuzzy controller method is applied to improve the overall performance of the WECS. The proposed method can retrieve the storing kinetic energy from the inertia of a wind turbine, perfectly. As a result, it can ensure a proficient power smoothing of the variable speed WECS. On the other hand, the grid side inverter is controlled by the fuzzy controller. This approach can reduce the fluctuation of DC link voltage and can deliver a smooth power to the power grid. The proposed method is compared with two other methods such as the maximum power point tracking control method and the without fuzzy controller method. A simple shunt circuit also includes in the DC link circuit. Therefore, during the system fault condition, the WECS can perform a stable operation. Effectiveness of the proposed method is verified by numerical simulations. Copyright © 2013 John Wiley & Sons, Ltd.     

基于超级电容储能的风电并网功率调节控制系统

风能是一种随机变化的能源,风速变化会导致风电机组输出功率的波动,对电网的电能质量产生影响,使用储能装置可以改善风电质量。通过在风电场并网的交流侧母线上并联超级电容储能单元,能实现对风电场功率的调节,减小功率的波动。文章设计了风电场并网及储能系统各部分的控制策略,在Matlab/Simulink仿真环境下创建了系统的仿真模型,验证了控制策略的正确性。仿真系统最终实现了电机侧变流器最大风能跟踪、电网侧变流器单位功率因数并网和超级电容储能单元对风电场并网功率的调节。     

Comprehensive control strategy for a variable speed cage machine wind generation unit

A comprehensive control strategy, that addresses all three control objectives in a wind generation system, i.e. control of the local bus voltage to avoid voltage rise, capture of the maximum power in the wind and minimization of the power loss in the induction generator is proposed. The control signals are the desired current wave shapes (instantaneous three-phase currents) of the rectifier and the inverter in a double-sided PWM converter system connected between the wind generating unit and the grid. Studies performed on a complete model for a variable speed cage machine wind generation unit, including wind profile, wind turbine, induction generator, PWM converter, local load and transmission line, show that even as the wind speed changes randomly, the proposed control strategy leads the system to the optimum operating conditions.     

基于SPWM的小型风电逆变系统的建模与仿真研究

以小型风力发电系统为研究对象,重点研究其逆变环节的设计,通过比较分析,主电路选择高频变压器形式,控制电路采用电压瞬时值反馈控制。利用MATLAB/Simulink软件建立了风电逆变系统的电路模型,给出了基于SPWM(Sinusoidal PWM)电压反馈控制的系统设计与仿真。在突加干扰的情况下仿真模型能很快稳定,具有较强的抗干扰能力,仿真结果验证了系统设计的可行性。在此基础上,完成了基于芯片TL494、IR2110和SG3525A的风电逆变控制系统的硬件设计方案。