不同标称功率光伏组件替换使用时的模型研究

针对某类光伏组件无备件更换时替换成其他标称功率光伏组件使用的可行性进行研究,通过Matlab软件仿真模拟不同标称功率光伏组件串联后的输出特性曲线,以实物实验来验证效果;并对不同标称功率光伏组件构成的光伏组串运行时的温度进行测试,用于判断光伏组件是否存在发热烧坏的情况。结果显示：1)采用不同标称功率光伏组件形成的光伏组串的I-U曲线和P-U曲线均在达到最大值之前出现了一个拐点,曲线不如采用相同标称功率光伏组件时的平滑。2)当两块较大标称功率光伏组件串联时,其中一块被替换为较小标称功率光伏组件后,其整体的最大输出功率会降低,但输出功率的这种变动不影响光伏组件的正常使用;而当两块较小标称功率光伏组件串联时,其中一块被替换为较大标称功率光伏组件后,其整体的最大输出功率基本不变。由此可知,当相同标称功率的光伏组件备件不足时,最好替换的光伏组件不要与被替换光伏组件的标称功率差异太大,否则容易引起光伏组串较大的输出功率损失。3)低标称功率的光伏组件与高标称功率光伏组件串联后,光伏组件的表面温度在正常范围内,光伏组件可正常运行。该研究为光伏组件备件不足带来的困扰提供了解决方案。     

基于并联光伏组件外特性的最大功率点跟踪方法

当阴影条件变化时,并联光伏组件的全局最大功率点(MPP)会随之改变.为了实现太阳能发电最大化,要求最大功率点跟踪(MPPT)方法始终能实时而准确地锁定住并联光伏组件的全局MPP.不同阴影条件下并联光伏组件会呈现不同的外特性特征,如多阶梯的电流电压特性以及多峰值的功率电压特性.基于此现象,该文提出一种基于并联光伏组件外特...     

多晶硅光伏组件湿热湿冻超量测试研究

基于IEC 61215标准中湿热(DH)、湿冻(HF)试验的环境条件参数,对组件连续施加超量的环境条件压力,分析其性能变化;并将其静置1年后复测其功率,发现长时间静置对其功率有很大影响;然后继续对组件进行环境试验,并置于户外曝晒,其间测量其功率变化;最后拆解组件,研究湿热及湿冻试验分别对组件造成的影响。研究发现:湿热试验DH3000是功率衰减的一个临界点,且对组件焊带腐蚀深度较深,汇流条腐蚀程度也较大;而长时间的湿冻试验静置后功率会大幅恢复,且湿冻试验使背板脆化相当严重,焊带整体腐蚀面积也较大。通过整个实验发现,组件在经过环境试验后,静置多久去测量其功率是一个需要重新考究的方面。     

工程应用中的光伏组件输出功率衰减率评估

本文利用型号为HT I-V 525W的I-V曲线测试仪对实际工程应用中光伏组件的电性能数据进行了实地测试,通过该测试仪将测试数据折算为标准测试条件(STC)下的最大输出功率,然后统计STC下光伏组件的最大输出功率并计算其输出功率衰减率,以评估光伏组件在工程应用中的输出功率衰减率情况.该研究可为光伏组件的清洗周期提供依据...     

异构焊带在光伏组件中的应用

焊带表面结构与光伏组件功率存在一定的对应关系,通过优化焊带表面结构可优化光伏组件内部光路,从而提升光伏组件功率。该文采用4种不同表面结构的焊带,制备出4种类型的光伏组件,结合理论模拟和实验测试,研究了焊带的表面压花结构对光伏组件功率及可靠性的影响。结果表明,在标准测试条件下,斜纹、疏竖纹、密竖纹异构焊带光伏组件与常规焊带光伏组件相比,功率分别提升了0.5%、1.18%和2%,密竖纹异构焊带光学增益最优;与标准测试结果一致,在户外运用时,密竖纹异构焊带光伏组件提升功率最优。另外,研究还发现,斜纹异构焊带光伏组件基本不受安装方向的影响,竖纹异构焊带光伏组件横装优于竖装。     

一种环境变化下的高效率光伏组件最大功率点跟踪方法

为实现在环境变化下光伏组件高功率发电的目的,提出一种环境变化下的高效率光伏组件最大功率点跟踪方法。基于Lambert W函数实现光伏组件最大功率点提取,利用光强电压阈值设定法达到环境变化的自动识别,实现环境变化下光伏组件最大功率点跟踪目的。仿真及实验表明,该方法可在环境变化中有效跟踪光伏组件最大功率点,与扰动观察相比,发电效率提高了8.2%。     

便携式I-V测试仪测试结果准确性的影响因素研究

采用便携式I-V测试仪在户外进行光伏组件最大功率测试时,测试结果会不同程度地受到外界因素的影响,从而使得到的光伏组件最大功率测试结果出现偏差.本文通过对比不同外界因素(比如:太阳辐照度、辐照计摆放位置、光伏组件工作温度及风速等)下测试得到的光伏组件最大输出功率值,分析不同外界因素对户外采用便携式I-V测试仪进行光伏组件...     

吕梁市光伏发电系统效率提升研究

对影响光伏发电系统发电量的因素进行了研究,通过实验方法确定了倾角、方位角和局部阴影遮挡对吕梁市光伏组件发电量的影响.结果表明:在接近地理纬度的角度范围内,倾角对光伏组件发电功率的影响在12％左右;调整方位角对光伏组件功率的影响较大,在合理跟踪方位角的情况下,可使光伏组件发电功率增长1倍;遮挡对光伏组件的发电功率影响很大...     

高辐照量下遮挡时PV组件性能特性模拟分析

为研究高辐照量下(辐射强度为1200 W/m~2)遮挡时的组件可靠性,根据能量守恒定律,结合电池的单二极管和反向特性数学模型,建立适合分析遮挡情况的光伏模组仿真模型,用以分析标准工况和高辐照量条件下组件的光电转换性能和组件工作温度特性、二极管工作特性。模拟计算结果表明:在高辐照量遮挡情况下,组件最大输出功率比标准工况大18.5%;组件正常运行时的最高温度比标准工况时高14℃,比实际工况高30℃。因此,在高辐照量的地区,光伏组件尽量选择安放在通风处。旁路二极管分布可沿用标准工况的设计方案。     

新型光伏焊带及其在提升光伏组件发电功率中的应用

在光伏组件中,焊带主要起电气连接的作用,同时焊带表面结构与光伏组件的发电功率存在一定的对应关系,焊带表面的结构也存在较大的优化空间。应用全反射原理,通过对光路的分析和计算,得出光伏焊带表面结构对组件功率的影响机理。通过两种新型光伏焊带表面结构方案的设计,分别制备出两种类型的光伏组件。当太阳光入射到光伏焊带表面时,光线在光伏焊带表面的反射路径会发生改变,使得光线在玻璃/空气界面发生全反射,这样会增加光伏组件内太阳能电池片的受光总量,从而增加太阳能电池片产生的电子-空穴对的数量,最终提升光伏组件功率。在IEC61215测试标准条件下,两种类型光伏组件的功率分别提升了0.38%和1.00%。     

氢燃料电池汽车全球技术法规第二阶段火烧试验方法研究

近期,氢燃料电池汽车全球技术法规（UN GTR 13）第二阶段为提高火烧试验可重复性提出的新方法,将对中国氢燃料电池汽车的发展产生重大影响。该文在分析火烧试验结果可重复性问题的基础上,系统研究火烧试验新方法的主要内容、特点及其提出的技术理由,指出中国标准制定、试验设施和技术研究面临的挑战,并提出若干建议。     

Study of fuel cell structure and heating method: Development of JARI's standard single cell

The effects of cell configuration, materials, assembly method, and temperature control method on the performance of Japan Automobile Research Institute's (JARI's) standard single cell were investigated in order to reproducibly estimate the influence of impurities. From the results, active electrode area, flow channel configuration, clamping torque, and thermal design of the cell were optimized. JARI's standard single cells are used for investigating hydrogen fuel, because they are easily assembled and disassembled, have uniform electric generation performance from one unit to another, and have high reproducibility from one test to another.     

净全辐射表全波灵敏度的校准

介绍了在室外用两台标准总日射表和两台黑体校准过的地球辐射表提供净全福照度、日间检定净全辐射表的全波灵敏度和谙检定其长波灵敏度的结果。数据再次证明，两者之间存在明显差异，必须加以区分并分别予以校准。使用中，当净 辐照度为正时用以灵敏度，为我时用长小波灵敏度。分析表明，短波灵敏度并无实用价值。     

Round robin on accelerated life testing of solar absorber surface durability

As degradation by ageing of solar absorber surfaces was identified to be an important quality factor, the Working Group MSTC (‘Materials in Solar Thermal Collectors') of the IEA-SHCP (International Energy Agency-Solar Heating and Cooling Programme) worked out a general test procedure for accelerated lifetime testing (ALT) of these materials, based on methods established by the former Task X of the IEA SHCP. The qualification test procedure was adopted by ISO and is presently dealt within ISO/TC 180 ‘Solar Energy'. The standard proposal in detail describes a procedure how to test the long-term stability of an absorber surface for the use in flat plate collectors for domestic hot water systems. The collectors service lifetime is assumed to be 25 years, at least. Degradation caused by thermal loads, high humidity and condensation and sulphur dioxide are regarded. In order to examine the feasibility and reproducibility of the test method the Working Group MSTC initiated a round robin test in accelerated life testing of solar absorber surfaces. The test was performed according to the ISO standard proposal dated January 1997. In total, five different industrially manufactured absorber coatings were available to the three participating laboratories. Tests concerning the thermal stability as well as the resistance to high humidity and condensation were performed by all three laboratories. The test for determining absorber surface corrosion resistance to air of high humidity containing sulphur dioxide was carried out by one lab only. The outcome of the round robin test shows very good agreement of the results of the different coatings tested for all of the laboratories. The feasibility and reproducibility of the method was fully confirmed.     

风力发电机组塔架螺栓连接公差问题研究

针对风力发电机组塔架法兰的螺栓连接,基于IEC 61400对其公差的要求和可能发生的平面度问题,采用有限元方法进行应力计算.结合实际风力发电机组法兰螺栓连接实例计算,对塔架法兰内倾量和平面度公差对筒壁和螺栓的影响进行总结,提出法兰内倾角公差设计方法,比较平面度公差对螺栓的影响,可为提高塔架法兰连接的可靠性提供更为严谨的...     

分光总日射表校准因子的迭代计算法

详细讨论了分光总日射表的校准方法。论证了以一台直接日射表和一台遮蔽的总日射表为标准的校准方法优于仅用一台直接日射表为标准的校准方法，并提出了分光总日射表校准因子的迭代计算法。该方法可以解决由于遮蔽的总日射表校准因子不准确而产生的误差。最后还讨论了在校准过程中时间准确的重要性，指出至少应准确到分，否则每分的误差通过太阳高度角的正弦会给直接日射值带来０．２％的系统误差。     

Particle density determination of pellets and briquettes

Several methods and procedures for the determination of particle density of pellets and briquettes were tested and evaluated. Round robin trials were organized involving five European laboratories, which measured the particle densities of 15 pellet and five briquette types. The test included stereometric methods, methods based on liquid displacement (hydrostatic and buoyancy) applying different procedures and one method based on solid displacement.From the results for both pellets and briquettes, it became clear that the application of a method based on either liquid or solid displacement (only tested on pellet samples) leads to an improved reproducibility compared to a stereometric method. For both, pellets and briquettes, the variability of measurements strongly depends on the fuel type itself.For briquettes, the three methods tested based on liquid displacement lead to similar results. A coating of the samples with paraffin did not improve the repeatability and the reproducibility.Determinations with pellets proved to be most reliable when the buoyancy method was applied using a wetting agent to reduce surface tensions without sample coating. This method gave the best values for repeatability and reproducibility, thus less replications are required to reach a given accuracy level. For wood pellets, the method based on solid displacement gave better values of repeatability, however, this instrument was tested at only one laboratory.     

PCA-PSO/GS-SVM组合方法在风电齿轮箱故障预测中的应用研究

在标准支持向量机(SVM)的基础上,引入主成分分析法(PCA)、粒子群算法(PSO)以及网格算法(GS),构建针对风力机故障的PCA-PSO/GS-SVM组合预测模型。相对于标准SVM,该模型采用PSO以及GS算法寻优参数,能够更准确地建立各变量间的相关关系以提高模型的预测准确性。以中国北方某风场2 MW风电齿轮箱在2017年上半年某2个月的SCADA监测数据为例进行分析。结果表明,对于以齿轮箱输出功率为例的骤变信号的预测,采用PSO算法寻优后的绝对误差均值是采用GS算法的3.0647倍,而对于以高速侧轴端温度为例的缓变信号的预测,则采用PSO算法更加合理;同时发现剔除训练样本数据中的奇异点能够有效提高模型的预测精度及其泛化能力。     

非标条件下太阳电池短路电流向标准条件下的转化

分析了在太阳电池测试过程中，模拟器的光谱失配、光强、太阳电池的光谱响应和测试时太阳电池PN结温度这四个因素共同对测试结果的影响。找到了太阳电池在非标准测试条件下测试结果向标准测试条件下转换的一般方法。给出诸多实验，并确定该种转换方法中的一些经验参数。     

Comparative study of durability test methods for pellets and briquettes

Different methods for the determination of the mechanical durability (DU) of pellets and briquettes were compared by international round robin tests including different laboratories. The DUs of five briquette and 26 pellet types were determined. For briquettes, different rotation numbers of a prototype tumbler and a calculated DU index are compared. For pellets testing, the study compares two standard methods, a tumbling device according to ASAE S 269.4, the Lignotester according to ÖNORM M 7135 and a second tumbling method with a prototype tumbler. For the tested methods, the repeatability, the reproducibility and the required minimum number of replications to achieve given accuracy levels were calculated. Additionally, this study evaluates the relation between DU and particle density.The results show for both pellets and briquettes, that the measured DU values and their variability are influenced by the applied method. Moreover, the variability of the results depend on the biofuel itself. For briquettes of DU above 90%, five replications lead to an accuracy of 2%, while 39 replications are needed to achieve an accuracy of 10%, when briquettes of DU below 90% are tested. For pellets, the tumbling device described by the ASAE standard allows to reach acceptable accuracy levels (1%) with a limited number of replications. Finally, for the tested pellets and briquettes no relation between DU and particle density was found.