Forecast of Power Generation for Grid-Connected Photo-voltaic System Based on Grey Theory and Verification Model

Being photovoltaic power generation affected by radiation strength, wind speed, clouds cover and environment temperature, the generating in each moment is fluctuating. The operational characteristics of grid-connected PV systems are coincided with gray theory application conditions. A gray theory model has been applied in short-term forecast of grid-connected photovoltaic system. The verification model of the probability of small error will help to check the accuracy of the gray forecast results. The calculated result shows that the ?model accuracy has been greatly enhanced.

Load Management Scheme Using Air Conditioning Electric Power Consumption and Photovoltaic Power System Generation

In the last few decades, in the world and also in the European Union, considerable resources had been invested in the rapid development of renewable energy sources and distributed generation in general. At the same time, power consumption is continuously increasing, and consumers are becoming more complex, which ultimately requires new investments in the distribution network. Concept of smart grids is generally accepted as a possible solution. Smart grid is a concept with many elements, where monitoring and control of every element in the chain of production, transmission, distribution and final consumption enable much more efficient delivery and use of electricity. One of the elements of smart grid efficiency is the ability of real-time demand-supply balancing. This balancing is carried out by monitoring of consumption and redistribution of electricity among individual end users, according to their needs. The aim of this paper is creating algorithm for real-time load management using power measurements. Algorithm for real-time load management at the ETFOS （Faculty of Electrical Engineering in Osijek）, Croatia is created based on measurements of photovoltaic power plant production, the power consumption of air conditioning system and the faculty building total electricity consumption. Expected result of real-time re-dispatching of air conditioners consumption, depending on the level of electricity production in photovoltaic power plant is decreasing peak demand of the faculty.

Large-Scale Distributed Photovoltaic Power Dispatching and Operation Management Review

Distributed photovoltaic power (PV) is the main development model of distributed generation. It is necessary to research on dispatching and operation management with large-scale distributed PV connected. This paper analyzes development status, technical requirement and dispatching and operation management situation of distributed PV in Germany and China. Then introduce the preparation of distributed PV dispatching and operation management criterion. Through summarizing the experiences and lessons of large-scale distributed PV development in Germany, it gives advice to the development of distributed PV dispatching and operation management in China.

Low Voltage Ride through Control Capability of a Large Grid Connected PV System Combining DC Chopper and Current Limiting Techniques

This paper presents the development and performance capability of a comprehensive Low voltage ride through (LVRT) control scheme that makes use of both the DC chopper and the current limiting based on the required reactive power during fault time. The study is conducted on an 8.5 MW single stage PV power plant (PVPP) connected to the Rwandan grid. In the event of fault disturbance, this control scheme helps to overcome the problems of excessive DC-link voltage by fast activation of the DC chopper operation. At the same instance, AC current is limited to the maximum rating of the inverter as a function of the injected reactive current. This helps overcome AC-over- current that may possibly lead to damage or disconnection of the inverter. The control scheme also ensures voltage support and power balance through the injection of reactive current as per grid code requirements. Selected simulations using MATLAB are carried out in the events of different kinds of fault caused voltage dips. Results demonstrate the effectiveness of the proposed LVRT control scheme.

Extended Quality Characterization of Grid Connected PV Inverters

The overall performance of photovoltaic （PV） inverter imphes many different technical issues.One of the key criterias is based on the measurement of the conversion and the maximum power point tracking （MPPT） efficiency and its applicable evaluation in practice.Intense work has been done in the last few years to formulate applicable standards for measuring static and dynamic efficiencies worldwide.Besides that,this work is presenting on novel methods of analysis on non-trivial system characteristics impacting the final evaluation on the overall performance of the PV inverter.The elaborated testing procedures for complex system behavior under highly nonlinear conditions （unintentional partial shading, mismatching of DC strings） are explained and characterized.With the help of experimental results, the exclusive impact on the overall efficiency is illustrated and helpful statements are given on the resulting technical characteristics of MPP strategies.

基于CSA-INC算法的光伏发电MPPT仿真研究

为提高最大功率点追踪的速度与准确性,并减小光伏阵列在局部阴影时光伏发电系统输出功率的损失与谐波含量,提出基于布谷鸟算法(CSA:Cuckoo Search Algorithm)和电导增量法(INC:Incremental Conductivity method)相结合的控制方法。在算法前期利用布谷鸟算法进行全局搜索,避免算法陷入局部最优解。后期利用电导增量法进行局部范围内细致搜索,锁定最大功率点。并且将此算法应用于并网控制,验证是否满足并网谐波含量要求。在Matlab/Simuink中建立了仿真模型,结果表明基于布谷鸟与电导增量法相结合的复合算法追踪速度更快,误差更小,满足并网谐波含量要求。

风-光-抽-柴并网型微网的优化运行研究

为抑制风电、光伏功率输出波动,提高消纳比例,建立风电、光伏、柴油发电及抽水蓄能电站组成的分布式并网型微电网模型。风电、光伏作为微电网的主要出力对象,柴油发电作为紧急备用供电措施,抽水蓄能电站作为能量储转设备完成对可再生能源的存储与转换。分析了微电网组成部分的出力特性及用户负荷,以运行成本及系统电能外购率最低为优化目标,建立优化运行数学模型,并结合实际算例,采用改进的多目标克隆选择算法进行求解,可以得到优化运行的Pareto解集,能够提供在运行成本和电能外购比例优化目标下的各个发电单元在各优化时段的出力,具有一定的理论研究与工程实践意义。

基于MMC-RPC的铁路光伏发电并网技术探究

通过对铁路光伏发电并网技术进行研究,分析了光伏发电系统并网的拓扑结构以及MMC-RPC并网结构的工作原理及技术优势,提出构建基于MMC-RPC结构的铁路光伏发电并网系统方案。同时结合铁路电力系统并网的电能质量问题,研究提出了基于MMC-RPC的并网控制策略,通过综合补偿、冗余保护、能量平衡和调制控制,改善电网电能质量,提高系统可靠性,为铁路光伏发电并网技术研究及方案实施提供参考。

Modeling and control of photovoltaic energy conversion connected to the grid

This paper presents modeling and control of a photovoltaie generator （PVG） connected to the grid. The parameters of the PVG have been identified in previous work （series and parallel resistance, reverse saturation current and thermal voltage） using Newton-Raphston and the gradient algorithm. The electrical energy from a PVG is transferred to the grid via two static converters （DC/DC and DC/AC）. The objective of the proposed control strategy is to maximize energy captured from the PVG. The adapted control law for extracting maximum power from the PVG is based on the incremental conductance algorithm. The developed algorithm has the capability of searching the maximum photovoltaic power under variable irradiation and temperature. To control the DC/AC inverter, an intelligent system based on two structures is constructed： a current source control structure and a voltage source control structure. The system has been validated by numerical simulation using data obtained from the PVG installed in the laboratory research （INSAT, Tunisia）.

Z-源逆变器在光伏发电系统中的应用

Z-源逆变器由于采用独特的X型Z-源网络,可以利用逆变器桥臂直通状态实现升压功能,从而使单级Z-源逆变器具有与两级并网系统相类似的性能。该文论述基于Z-源逆变器的光伏并网系统在变换效率、可靠性以及成本方面的优势,提出了一种新的单级Z-源逆变器并网系统两级控制策略,该控制策略实现了MPPT控制和逆变器并网控制,使Z-源光伏并网系统能够动态跟踪光伏电池最大功率点电压,输出电流与电网电压同相位,从而达到较高的功率因数。软件仿真和实验分析证明了该控制方法具有优良的动、静态特性,适合各种变化的天气情况。

大型滚装船船电-光伏并网系统构建及电能质量分析

随着绿色船舶和新型船体设计概念不断被推广,将光伏系统与船舶电力系统进行并网运行成为未来船舶发展的方向。为了给大型远洋船舶光伏并网发电系统的设计和应用提供依据,以适宜搭建光伏阵列的大型滚装船为研究对象,构建一种船电-光伏并网系统,对该系统的构建流程和系统结构进行详细阐述,并根据大型滚装船船电-光伏并网系统的特点,对电能质量问题及影响因素进行分析。研究成果可为大型远洋船舶光伏并网发电系统的设计和应用提供参考依据。

光伏并网发电系统的MPPT-电压控制策略仿真

在配电网络的末端,负载的无功波动将会对电网供电电压产生较大的影响,对光伏发电系统并网处系统侧的交流电压进行控制,可以提高系统的电压水平。根据光伏并网系统的结构,采用外环为电压环、内环为并网电流环的双环控制。通过abc/dq0变换将并网电流解耦为有功分量和无功分量,引入最大功率点跟踪(maximum power point tracking,MPPT)提供的直流侧电压参考量的闭环控制调节并网电流的有功分量,引入交流侧电压参考量的闭环控制调节并网电流的无功分量,实现了具有MPPT和电压控制能力的三相光伏并网发电技术。仿真结果表明MPPT-电压控制策略既能够实现光伏并网的最大功率点跟踪,也能够控制光伏发电系统接入点的交流电压,进一步提升了光伏并网发电系统的应用前景。

三相光伏并网Z-源逆变器的比例谐振控制

将具有独特的X型网络的Z-源逆变器应用于光伏并网系统,利用逆变器桥臂直通状态实现直流侧升压。对Z-源逆变器的拓扑结构和工作原理进行了详细的分析;根据电网电压定向的控制策略结合比例谐振控制器,利用改进的空间矢量脉宽调制方法实现了逆变器并网控制,使Z-源光伏并网系统能够动态跟踪光伏电池最大功率点电压,输出电流和电网电压相位,实现单位功率因数运行和电流波形正弦化。仿真结果表明系统具有良好的静态和动态性能,验证了采用的系统结构和控制策略的有效性和可行性。

基于和声搜索-高斯过程混合算法的光伏功率预测

光伏发电并网后会对电网产生冲击,影响电网稳定。通过对光伏发电功率的特性分析,在研究高斯过程算法原理的基础上,建立了基于高斯过程的光伏发电功率预测模型。针对传统高斯过程中优化超参数采用共轭梯度法存在的缺陷,提出采用和声搜索算法代替共轭梯度法,得到一种基于和声搜索优化的混合高斯过程模型。仿真结果表明,采用和声搜索优化后的高斯过程混合算法比传统高斯过程方法的预测精度更高。

基于EMD和ABC-SVM的光伏并网系统输出功率预测研究

针对光伏发电系统的输出功率具有非平稳性和随机性的特点,提出一种基于经验模态分解(EMD)和人工蜂群算法(ABC)优化支持向量机(SVM)的光伏并网系统输出功率预测模型。首先根据预测日的天气预报数据,构建相似日的15 min输出功率时间序列。然后,将输出功率时间序列进行经验模态分解,得到不同尺度下的固有模态分量IMFn和趋势分量Res,针对每个IMF分量和趋势分量分别建立相应的支持向量机预测模型,并对SVM模型参数进行人工蜂群算法寻优预处理。最后,将每个模型预测的结果进行合成重构,得到光伏并网系统输出功率的预测值。通过实际数据测试表明:基于EMD和ABC-SVM的功率预测模型同单一SVM预测模型及未经优化的EMD-SVM预测模型相比,具有更快的运算速度和更高的预测精度。

基于粒子群-稀疏贝叶斯混合算法的光伏功率预测方法

提出一种包含天气预报信息的了粒子群-稀疏贝叶斯混合算法的发电预测理论,结合历史发电量数据和气象因素分析影响光伏发电量的主要因素,采用基于辐照度、光伏发电量及环境温度等建立的预测模型。最后用国网风光储示范工程的数据进行测试,预测结果证明了方法的有效性。

高增益DC-DC变换器在光伏系统中的应用研究

以光伏、燃料电池为代表的新能源产业正逐渐兴起,通过高升压的DC-DC变换器将光伏输出电压提升到常规母线直流电压,用来保证正常的并网逆变,但由于其输出电压等级较低,很难达到应用场合所需的电压要求。为了克服这种缺陷,主要介绍目前光伏发电行业不同应用场合下的高增益直流变换器拓扑,同时对高增益变换器进行分类。把几种高增益直流变换器的拓扑进行总结,并分析其工作原理以及优缺点,指出未来直流变换器拓扑的发展趋势和所面临的挑战。

功率前馈的准Z源光伏并网逆变器Quasi-PR控制

为了加快准Z源光伏并网逆变器的动态响应,避免电网电压矢量定向控制策略需解耦控制和多次坐标变换的不足,同时提高并网电流控制器对电网频率偏移的适应范围,将功率前馈及准比例谐振控制引入准Z源光伏并网系统中。在两相静止坐标下,将功率前馈、准比例谐振控制与直通分段空间矢量脉宽调制(SVPWM)相结合,设计了并网系统的完整控制策略。在Matlab/Simulink中搭建了系统仿真模型,并与传统控制进行对比分析。仿真结果表明:当外界环境发生变化时,采用功率前馈的准比例谐振控制策略能使系统较快地过渡到另一个稳态,且可实现对给定值的无静差跟踪控制,抗电网频率偏移能力强。

光伏电源利用直流-同步电机并网控制方法的研究

针对光伏并网逆变器存在故障率高、谐波含量大、控制复杂等问题,提出一种实用的光伏电源利用直流-同步电机并网的方案。该光伏并网系统中光伏电源为直流电机供电,直流电机带动同步电机同轴旋转,实现直流与交流电能之间的转换。并网控制系统包括光伏阵列最大功率跟踪控制、电机转速控制和同步电机端电压控制,当自动装置检测和判断同步电机满足并网条件时合闸并网。光伏系统并网后,同步电机的输出功率跟随光伏阵列输出功率的变化而变化。MATLAB/Simulink仿真验证了该并网方案的可行性,该方案得到的并网电压、电流波形质量好,能够同时向电网提供有功和无功功率,有利于改善电网功率因数。

储能型光伏Quasi-TZ源逆变器研究

带储能元件准Z源(Quasi-Z source)逆变器可平衡光伏阵列能量注入电网时所产生波动,传统带储能元件准Z源逆变器在蓄电池放电时因输出电流不连续而产生功率损耗,升压能力局限性大。文章提出储能型光伏Quasi-TZ源逆变器拓扑,解决蓄电池放电时功率损失问题,缓解传统Z源系列逆变器启动时电流冲击,利用T源逆变器升压能力拓宽输出功率范围。提出储能型光伏Quasi-TZ源逆变器控制策略,提高输出电压稳定性。仿真结果验证了该设计拓扑结构的正确性和优越性。