基于Matlab/Simulink的两级式光伏并网系统仿真分析

研究一种单相光伏并网发电控制仿真系统。利用Matlab2008b/Simulink,采用boost电路和逆变电路两级式结构,其中采用电导增量法的最大功率跟踪功能在boost电路中实现,并网控制通过采集电网电压参数和逆变输出电流电压参数在逆变电路中通过PI调节实现。通过光伏阵列通用模型验证最大功率跟踪模块的正确性,通过并网实验验证并网跟踪性能。基本实现了光伏阵列最大功率点的快速、准确跟踪功能和逆变输出电流电压与电网电压的同频同相,保证了输出电流为正弦波形且纹波较少,能够快速跟踪电网电压的变化。证明此系统在实际中是可行的。     

基于改进电导增量法的光伏MPPT控制

为了提高光伏发电效率及系统稳定性,需要对光伏阵列进行最大功率点跟踪(MPPT)控制.针对传统扰动观测法存在的系统振荡及误判问题,提出一种改进的电导增量法,通过计算系统当前时刻电导与电导变化率的差值,利用积分器进行调节,消除其差值,最终实现对系统最大功率点的稳定跟踪.为验证所提算法的有效性,将改进电导增量法与传统扰动观测...     

改进的电导增量法在光伏系统MPPT中的应用

分析了太阳能光伏阵列的输出特性和传统最大功率跟踪方法的优缺点,并在此基础上提出了一种改进的电导增量法.用Matlab/Simulink对Boost DC/DC变换器系统进行了建模与仿真,将改进的方法和传统的电导增量法分别应用于控制该系统.仿真结果表明,在外界环境变化的情况下,改进的方法在保证系统稳定性的前提下,使得光伏...     

基于DSP控制的光伏并网逆变器最大功率的跟踪问题

在对太阳电池的等效电路及特性曲线分析的基础上．提出了最大功率点的跟踪（MPPT）方法，设计了一套基于DSP（TMS320F240）控制能实现最大功率跟踪的光伏并网逆变器，通过实际测试发现原有逆变器设计在跟踪最大功率点时存在运行不稳定的问题，经过分析提出了改进方案，实验证明改进后的逆变器运行更加稳定。     

基于新型Z源逆变器的光伏并网发电系统

逆变器是光伏发电系统的重要组成部分,逆变器结构的选择与设计至关重要。文章从传统逆变器局限性入手,在重点分析了Z源逆变器的拓扑结构和工作原理基础上,提出新型Z源逆变器的拓扑结构,并设计了一种基于新型Z源逆变器的光伏并网发电系统。系统采用高性能DSP作为主控制芯片,研究了一种加入直通零矢量的双闭环控制方案,采用扰动观测法与最小二乘法相结合的最大功率点跟踪(MPPT)控制方法,使整个系统更加完善、安全。     

一种基于变步长电导增量法的自适应MPPT控制策略

光伏电池是太阳能光伏发电系统的基本组件,其输出特性易受到工作环境的制约,基于此利用优化的最大功率点跟踪(MPPT)策略能够可以有效地提高光伏发电系统的发电效率。文章针对传统电导增量法的实时性和容错性缺陷,提出了一种基于变步长电导增量法的自适应MPPT控制算法,该算法引入了一套全新的步长调节方法,能够根据外界环境的变化实时调整扰动步长,在一定程度上解决了辐照强度剧烈变化情况下传统电导增量法动态响应速度慢且容易发生误判的问题。文章通过仿真实验验证了所提算法的有效性和合理性。     

一种改进的变步长电导增量光伏电源MPPT控制方法

光伏系统的最大功率点跟踪方法可以最大限度地利用光伏电池所能产生的电能,因此成为提高光伏发电系统运行效率、降低光伏电能成本的研究热点。针对目前常用的扰动观察法速度较慢、电导增量法在最大功率点附近有较大振荡的问题,提出一种改进变步长电导增量的最大功率点跟踪控制方法,该方法既具有电导增量法快速跟踪的优点,又能准确、稳定地跟踪到最大功率点,因此更适于提高光伏电源的能源利用率。对所提方法进行了仿真分析,并比较了几种MPPT算法的跟踪效果,结果表明,所提方法具有快速性、稳定性和有效性。     

光伏并网发电系统的MPPT改进算法及其在光照突变时的仿真

利用MATLAB软件中的S函数编写了光照突变时光伏组件的模型,并依此建立了一个三相光伏并网发电系统的仿真模型。对传统的最大功率点跟踪（MPPT）算法进行了分析,提出了扰动观测法和电导增量法的改进算法,给出了基于光照突变时传统的恒定电压法和所提改进算法的跟踪仿真曲线,通过根据跟踪曲线的局部和总体的相对误差以及方差比较了这些算法的效果,指出改进的扰动观测法是一种特性较好并具有实用性的MPPT算法。由于仿真分析采用了三相并网运行光伏发电系统的仿真模型,得到的结论更适合作为实际应用参考。     

基于模型预测控制的MPPT控制策略

提出一种新的基于模型预测控制(MPC)的最大功率点跟踪(MPPT)优化算法。该目标控制算法把基于电流的改进型电导增量法与模型预测控制算法相结合,完成对光伏阵列最大输出功率的快速跟踪。在算法执行过程中,通过建立系统性能指标函数,评价与估算出未来控制变量的动作,从而决定P-U曲线的跟踪方向。仿真结果表明:该控制策略有效地解决了传统电导增量法在外界环境激烈变化时所产生的误判现象,在提高系统稳定性的同时,大大地减少了最大功率点跟踪时间和系统的能量损耗。     

两级式光伏并网系统建模与控制研究

建立了由Boost DC/DC电路和LCL滤波器的逆变电路组成的两级式单相光伏并网系统数学模型。前级Boost DC/DC电路采用变步长的扰动观察法调节占空比改变光伏阵列的输出电压,实现最大功率点的跟踪;后级LCL滤波器逆变电路采用电网电压前馈和电流跟踪控制技术,利用前馈补偿有效抑制电网波动,具有很好的跟随性能和抗干扰性能;改善系统的动态性能,有效减少系统产生的高次谐波。最后用Matlab软件对该模型进行了仿真,证明了建模和控制方法的有效性和可行性。     

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。     

可调度型光伏并网逆变器直接电流控制策略研究

为实现光伏电站有功功率的平稳输出以及灵活调度,文章提出了一种基于优化型DDSRF-PLL锁相环的直接电流控制方案。该方案将广义二阶积分器(SOGI-QSG)与解耦双同步旋转坐标系锁相环(DDSRFPLL)相结合,并应用于直接电流控制方案中。在Matlab/Simulink软件中对控制策略进行了仿真,结果表明,该控制策略下的光伏并网逆变器可以实现有功功率的平稳输出与灵活调度,动态性能优异,抗干扰能力强。     

New control strategy for 2-stage grid-connected photovoltaic power system

This work deals with the performances and responses of a grid-connected photovoltaic (PV) plant in normal and disturbed modes. The system is composed of a solar array, a dc–dc converter and a three-phase inverter connected to the utility grid. On the one hand a suitable control of the dc–dc converter is developed in order to extract the maximum amount of power from the PV generator. On the other hand an active and reactive power control approach (PQ) has been presented for the inverter. This method can provide a current with sinusoidal waveform and ensure a high power factor. Therefore, the grid interface inverter transfers the energy drawn from the PV into the grid by ensuring constant dc link voltage. Modeling and controlling were carried out using the informational graph of causality and the macroscopic energy representation methods. The simulation under MATLAB/SIMULINK and the experimental results show the control performance and dynamic behavior of grid-connected PV system in normal and disturbances modes.     

Sliding mode controller for the single-phase grid-connected photovoltaic system

A sliding mode controller for the single-phase grid-connected photovoltaic system has been proposed in this paper. Contrary to the conventional controller, the proposed system consists of maximum power point tracker (MPPT) controller and sliding mode current controller only. The proposed MPPT controller generates current reference directly from the solar array power information and the current controller uses the sliding mode technique for the tight regulation of current. The new MPPT controller does not require the measurement of the voltage derivative which can be a cause of divide-by-zero singularity problems. The sliding mode controller has been constructed based on a time-varying sliding surface to control the sinusoidal inductor current and solar array power simultaneously. The proposed system can avoid the current overshoot and make optimal design for the system components. The structures of a proposed system are simple, but they show the robust tracking property against modeling uncertainties and parameter variations. The mathematical modeling is developed and the experimental results verify the validity of the proposed controller.     

Harmonic distortion assessment for a single-phase grid-connected photovoltaic system

Nowadays, grid-connected photovoltaic (PV) systems constitute an emerging technology. This has given rise to concerns about their contribution to harmonic distortion levels in utility grids. Valuable insight into the electrical behavior of such a system, including its impact on power quality, can be obtained through extensive simulation studies. In this paper, models are developed with a focus on not only accurate but also fast simulation of grid-connected PV systems. First, time-consuming processes are identified and discussed. These are mainly associated with the semiconductor power switching devices and the non-linear characteristics of the system components (isolation transformer, PV generator). Next, models are developed in order to increase simulation speed by avoiding time-consuming procedures. The validity of the approach is ascertained by comparing simulation results with published measurements. A case study is then performed in order to obtain current and voltage waveforms and, subsequently, harmonic distortion levels. Further simulations are carried out using different values for various system parameters in order to make an assessment of their impact in terms of waveform distortion.     

A novel multi-model neuro-fuzzy-based MPPT for three-phase grid-connected photovoltaic system

This paper presents a novel methodology for Maximum Power Point Tracking (MPPT) of a grid-connected 20 kW photovoltaic (PV) system using neuro-fuzzy network. The proposed method predicts the reference PV voltage guarantying optimal power transfer between the PV generator and the main utility grid. The neuro-fuzzy network is composed of a fuzzy rule-based classifier and three multi-layered feed forwarded Artificial Neural Networks (ANN). Inputs of the network (irradiance and temperature) are classified before they are fed into the appropriated ANN for either training or estimation process while the output is the reference voltage. The main advantage of the proposed methodology, comparing to a conventional single neural network-based approach, is the distinct generalization ability regarding to the nonlinear and dynamic behavior of a PV generator. In fact, the neuro-fuzzy network is a neural network based multi-model machine learning that defines a set of local models emulating the complex and nonlinear behavior of a PV generator under a wide range of operating conditions. Simulation results under several rapid irradiance variations proved that the proposed MPPT method fulfilled the highest efficiency comparing to a conventional single neural network and the Perturb and Observe (P&O) algorithm dispositive.     

A grid-connected photovoltaic power conversion system with single-phase multilevel inverter

This paper presents a grid-connected photovoltaic (PV) power conversion system based on a single-phase multilevel inverter. The proposed system fundamentally consists of PV arrays and a single-phase multilevel inverter structure. First, configuration and structural parts of the PV assisted inverter system are introduced in detail. To produce reference output voltage waves, a simple switching strategy based on calculating switching angles is improved. By calculated switching angles, the reference signal is produced as a multilevel shaped output voltage wave. The control algorithm and operational principles of the proposed system are explained. Operating PV arrays in the same load condition is a considerable point; therefore a simulation study is performed to arrange the PV arrays. After determining the number and connection types of the PV arrays, the system is configured through the arrangement of the PV arrays. The validity of the proposed system is verified through simulations and experimental study. The results demonstrate that the system can achieve lower total harmonic distortion (THD) on the output voltage and load current, and it is capable of operating synchronous and transferring power values having different characteristic to the grid. Hence, it is suitable to use the proposed configuration as a PV power conversion system in various applications.     

基于双闭环策略的光伏并网逆变器鲁棒H_∞控制

光伏并网系统中,为了抑制逆变器参数不确定和外界干扰对输出电能的影响,提出了鲁棒双闭环控制策略。首先设计电压环线性化自抗扰鲁棒控制器,以稳定直流侧母线电压;其次建立系统电流环的广义参数不确定模型,并利用LMI设计了电流环鲁棒H∞控制器,实现对逆变器有功电流和无功电流的精确控制。通过仿真与传统PI控制方法进行比较,验证了该控制策略可以有效地消除模型不确定因素和外界扰动对系统输出性能的影响,增强光伏并网系统的鲁棒稳定性。     

基于模糊控制的无电压传感器光伏系统MPPT研究

基于光伏并网发电系统直流母线电压恒定的特点,定义了一个由光伏电池输出电流和Boost变换器占空比表示的等效功率,根据该等效功率与Boost变换器占空比的关系深入分析了一种无电压传感器最大功率点跟踪(MPPT)算法。为了实现变步长跟踪以保证MPPT算法的快速性,将模糊控制与无电压传感器MPPT算法相结合,改善了系统的动态特性。基于Matlab/Simulink平台搭建了光伏并网发电系统模型,将该算法与传统的扰动观测法进行比较,结果表明,在保证稳态精度的基础上,基于模糊控制的无电压传感器MPPT算法具有更快的跟踪速度,并在光照强度和温度变化的条件下证明了该算法具有更好的鲁棒性。