基于PSpice的光伏并网系统仿真研究

采用DC／DC和DC／AC两级拓扑结构对光伏并网系统进行了研究和设计,采用改进的定电压跟踪法（CVT）实现最大功率点闭环跟踪,并将PWM控制器引入并网逆变中,采用三角波比较方式实现SPWM电压逆变和输出电流的波形跟踪与控制,在电压、电流内环的基础上引入功率外环以实现系统前后级功率平衡和能量管理,采用基于PSpice的光伏电池仿真模型对所设计光伏并网系统进行了仿真。仿真结果表明,基于PSpice的光伏仿真模型能够有效地模拟实际光伏并网系统的行为特征,将PSpice软件用于光伏发电系统的仿真是可行的。     

基于最优梯度法MPPT的单相光伏并网逆变器设计

光伏并网发电是新能源发展的趋势。目前单相光伏并网过程中存在能量利用率低、电流谐波量大等缺点,且逆变器体积较大、价格昂贵。本文介绍的单相光伏并网逆变器系统在DC/DC变换部分利用LLC谐振半桥电路代替传统的BOOST电路,有效的降低了开关管功耗和噪声,并采用最优梯度法实现了最大功率点跟踪。     

光伏并网的控制策略与最大功率点跟踪的仿真分析

太阳能是一种丰富干净的可再生性能源,研究可靠的光伏并网发电系统控制策略和光伏电池输出特性与最大功率跟踪是非常重要。该文分析了光伏电池的工程数学模型,根据光伏电源输出特性与交流电源之间功率流动特征,提出了并网控制方案采用电压电流双闭环控制结构方法相结合的单级式光伏并网系统,使光伏电源并网逆变器输出电流完全与电网电压相位一致。此外,针对最大功率跟踪算法的实现和并网控制策略的配合问题进行了稳定性分析,最后通过仿真与实验验证了理论分析的正确性及控制策略的可行性。     

基于推挽电路的光伏并网发电微型逆变器研究

随着新能源的逐步推广,光伏并网发电系统得到了发展。其系统通常由多块光伏电池板串联依此提高整个光伏支路电压,通过DC／DC变换器或DC／AC逆变器连接负载或电网。针对以往方式,本文研究了一种由前级推挽正激电路的变换器及后级Dc／Ac逆变器两级联接式的光伏并网发电微型逆变系统。其前级通过光伏电池板最大功率点跟踪进行高频准单极性控制,后级采用流内环,电压外环双闭环控制。仿真研究表明,该系统具有并网电流质量高,动态特性好,最大功率点跟踪精确、效率高、稳定性高等优点。     

500W光伏并网逆变器设计

光伏并网发电系统是光伏系统发展的趋势.根据光伏并网发电系统的特点,设计了一套额定功率为500W的光伏并网逆变器,该并网逆变器能实现最大功率跟踪和反孤岛效应控制功能,控制部分采用基于TMS320F240型DSP的电流跟踪控制策略,实现了与网压同步的正弦电流输出.     

三相单级式光伏并网控制策略仿真

根据单级式光伏并网系统的拓扑结构及工作原理,建立了基于电网电压定向的矢量控制的并网逆变系统.该系统控制部分采用了最大功率跟踪、电压外环、电流内环的控制策略,保证光伏系统最大功率输出,实现并网电流与电网电压同频同相,高功率因素运行.     

基于MATLAB光伏并网逆变系统的仿真研究

光伏并网发电系统是光伏发电系统发展的趋势。文中介绍了单极式光伏系统的拓扑结构和实现最大功率的工作原理,阐述了电导增量法实现MPPT的基本思想。根据光伏系统并网发电拓扑结构,设计了一套新型的实现最大功率跟踪的单极式光伏并网逆变器。逆变器控制部分由DSP实现最大功率跟踪和输出电流跟踪控制,实现了逆变输出电流与电网同步,且高功率因数运行。仿真结果表明,单极式光伏并网逆变系统能准确跟踪太阳能电池最大功率点,并具有较好的稳定性。     

交错并联式并网MATLAB仿真系统研究

对于小型光伏并网发电系统,文中详细分析交错两级式并网系统。直流侧为双重的BOOST升压电路实现最大功率控制,采用扰动观察法实现最大功率点跟踪,并网逆变器的控制策略电压外环电流内环的双环控制,其中电流内环为滞环控制方式,并网逆变器的输出电流跟踪电网电压,实现功率因数为1的并网方式。文中给出了基于MATLAB的系统仿真模型,结果表明光伏电池能较好地实现最大功率点跟踪,电感容量减小,并且逆变后成功并网。     

光伏发电中并网系统的节能控制器的设计与实现

设计并实现光伏发电中并网系统的节能控制器,给出硬件软件设计流程。设计光伏并网方案模块分析获取的电压电流值,得到光伏阵列输出的最佳电流值,将该值反馈到并网电流管理模块中,对并网变流器输出电流实时调控,确保其处于最佳状态,使得并网电能的消耗最低化。通过小波分析方法检测光伏电网孤岛效应,并调控并网电流定位模块终止工作,避免能量的浪费,实现节能控制。实验结果表明,所设计控制器节能控制效果显著,可实现能耗的均衡。     

基于DSP的光伏并网逆变器的设计

光伏并网发电系统是光伏系统发展的趋势,文章根据光伏并网发电系统的特点,设计了一套基于数字信号处理器TNS320F2407控制的单相光伏并网逆变器。分析了系统的结构和控制原理,设计了最大功率点跟踪算法和锁相环的软件设计流程图。实验结果表明并网电流波形良好,逆变器输出的电流基本与电网电压同频同相,并网的功率因数近似为1。     

连铸坯视觉定重线结构光平面调整方法研究

鉴于传统三电平逆变电路存在谐波含量高的缺点, 在分析模块化多电平换流器(MMC)工作原理的基础上, 提出使用模块化多电平电路实现光伏并网逆变功能, 采用微分-跟踪器法实现光伏阵列最大功率点跟踪(MPPT)及逆变器PQ解耦控制, 实现了光伏系统以单位功率因数并网。在PSCAD中建立光伏并网系统动态仿真模型, 仿真结果表明, 所建模型具有开关损耗低、谐波量小的优点, 验证了所提方法的正确性和可行性。     

Grid-Connected Photovoltaic Multistring PCS With PV Current Variation Reduction Control

In this paper, a grid-connected photovoltaic (PV) multistring power conditioning system with PV input current reduction control is proposed. An improved maximum power point tracking (MPPT) method for the multistring converter is suggested. The suggested MPPT algorithm tracks the maximum power point even though measurement errors exist. To reduce the PV current variation introduced by the inverter, a PV current variation reduction control is suggested. This PV current variation reduction control reduces the PV current variation without additional components. The low current variation reduces the filter size and improves the MPPT efficiency. All algorithms and controllers are implemented on a single-chip microcontroller. Experimental results obtained on a 3-kW prototype show high performance such as a MPPT efficiency of 99.7%, an almost unity power factor, a power efficiency of 96.7%, and a total harmonic distortion of 2.0%.     

单相光伏并网逆变器控制策略研究与设计

针对光伏并网逆变器并网后其本质上为电流源的特点,采用STM32F103VET6型ARM芯片作为系统的控制核心,制造了一台5 kW单相光伏并网型逆变器。采用了固定开关频率的电流瞬时值控制技术来实现对并网电流的控制,在控制策略中加入了电压前馈来抑制电网电压对逆变器输出电流的影响,使用二阶电流预估来抵消SPWM波形延时对系统控制的影响。并且优化了最大功率点跟踪（MPPT）。实验证明,该逆变器样机性能完全达到设计要求。     

基于DSP的单级式光伏并网逆变器的数字控制系统设计

单级式光伏并网逆变器具有转换效率高、体积小、成本低等优点,但在控制实现上却较为复杂,对太阳能电池的最大功率跟踪和输出电流正弦度及单位功率因素化的控制目标须同时得到保证。结合单同步坐标系软件锁相环和空间矢量脉宽调制算法,详细地阐述了数字控制系统的设计,针对其中的电压电流双闭环控制结构和前馈解耦控制策略进行着重分析。搭建光伏并网逆变器实验平台,采用TMS320F2812数字信号处理器作为核心芯片对数字控制系统加以实现,实验结果表明控制系统具有较高的控制精度和较好的控制性能。     

单相光伏并网逆变器无差拍控制的研究与仿真

光伏并网逆变器是光伏发电系统的主要部件,为了达到更好的效率输出更高质量的电能,对逆变器电流进行快速有效的控制尤为关键。该文简单介绍了当前光伏并网逆变器的几种常用控制方法及其基本思想,分析了并网逆变器的工作原理和无差拍控制方法的原理,给出了逆变器脉冲宽度的计算和参考电流的获取方法,通过MATLAB/Simulink软件仿真表明,无差拍控制在单相光伏并网逆变器控制中动态响应特性好,控制方便,电流跟踪电网电压波形好。     

Multilevel Inverter For Grid-Connected PV System Employing Digital PI Controller

This paper presents a single-phase five-level photovoltaic (PV) inverter topology for grid-connected PV systems with a novel pulsewidth-modulated (PWM) control scheme. Two reference signals identical to each other with an offset equivalent to the amplitude of the triangular carrier signal were used to generate PWM signals for the switches. A digital proportional-integral current control algorithm is implemented in DSP TMS320F2812 to keep the current injected into the grid sinusoidal and to have high dynamic performance with rapidly changing atmospheric conditions. The inverter offers much less total harmonic distortion and can operate at near-unity power factor. The proposed system is verified through simulation and is implemented in a prototype, and the experimental results are compared with that with the conventional single-phase three-level grid-connected PWM inverter.     

Granular control of photovoltaic arrays by means of a multi‐output Maximum Power Point Tracking algorithm

In this paper, a Distributed Maximum Power Point Tracking (D‐MPPT) approach in photovoltaic (PV) applications is discussed. The proposed control method is suitable for the granular control of the PV generator at a module level or even at a sub‐module level. D‐MPPT is usually implemented by means of independent converters, each one of them running its own MPPT algorithm. Instead, the architecture proposed in this paper consists of only one digital controller, implementing a multivariable MPPT algorithm based on the Perturb and Observe approach, acting on a number of dc/dc converters, each one of them dedicated to a single PV module. The proposed control strategy reduces the number of current sensors with respect to the classical D‐MPPT architecture and tracks the maximum power evaluated at the dc/dc converters' output. Planar solid immersion mirror simulations and experimental results confirm the validity of the approach and of the design guidelines proposed in the paper. Copyright © 2012 John Wiley & Sons, Ltd.     

Flyback Inverter Controlled by Sensorless Current MPPT for Photovoltaic Power System

This paper presents a flyback inverter controlled by sensorless current maximum power point tracking (MPPT) for a small photovoltaic (PV) power system. Although the proposed system has small output power such as 300 W, a few sets of small PV power systems can be easily connected in parallel to yield higher output power. When a PV power system is constructed with a number of small power systems, the total system cost will increase and will be a matter of concern. To overcome this difficulty, this paper proposes a PV system that uses no expensive dc current sensor but utilizes the method of estimating the PV current from the PV voltage. The paper shows that the application of this novel sensorless current flyback inverter to an MPPT-operated PV system exhibits satisfactory MPPT performance similar to the one exhibited by the system with a dc current sensor as well. This paper also deals with the design method and the operation of the unique flyback inverter with center-tapped secondary winding.