船用柴油机功率测量不确定度评定

针对船用柴油机功率测量存在的不确定度,根据JJF1059-2012《测量不确定度评定与表示》中规定的方法,对标定工况下发动机功率测量不确定度进行评定,得出影响不确定度较大的分量以及原因,在此基础上,提出了对船用柴油机功率测量时测功器选择的建议。     

通用汽油机功率测量不确定度研究

按JJF1059-1999<测量不确定度评定与表示>规定的程序和方法,依据通用小型汽油机台架性能试验方法,对引起通用汽油机功率测量结果不确定度的因素逐一进行评定,计算各不确定度分量,找出不确定度主要因素,采取适当措施,提高通用汽油机功率测量结果的质量,促进测量不确定度评定工作在内燃机功率测量方面的应用.     

太阳能用水平热管传输功率测量不确定度评定

本文介绍了太阳能用水平热管传输功率检测装置的组成和工作原理,并对传输功率测量的不确定度进行了分析和评定。     

热电偶测量不确定度分析及应用

本文简述了热电偶的测温原理,重点对二等标准热电偶的测量不确定度进行了分析,并介绍了热电偶的特性及实际应用中的问题。     

专用游标卡尺的测量不确定度分析

分析专用游标卡尺的误差来源 ,计算出专用游标卡尺的测量不确定度 ,并给出用专用游标卡尺测量活塞销孔挡圈槽距离为 L=65 .0 0 0 .3 0 0 .10 mm的活塞测量结果。     

圆柱度的测量不确定度分析与评定

简要介绍了用Talyrond 2 65型圆度仪测量零件圆柱度的方法及其误差来源 ,通过分析 ,找出了对圆柱度测量不确定度起主要作用的误差分量 ,并举例说明了不同高度零件圆柱度测量不确定度的计算与评定方法。当测量的结果被用于过程控制时 ,不确定度的评价很重要。     

柴油机输出功率测量结果的不确定度评定

依据往复式内燃机测量方法,按照测量不确定度评定方式,对影响柴油机输出功率的主要因素逐一进行评定,计算不确定度分量,最终合成,求得在标定工况下柴油机输出功率的扩展不确定度。     

活塞斜槽角度及测量不确定度分析

本文介绍了三坐标测量机测量活塞斜槽角度的测量方法,以及测量不确定度分析。     

涡街流量计测量系统不确定度的分析

通过分析涡街流量计在液体和气体流量测量应用中的工作原理,讨论了涡街流量计测量系统中仪器尺寸精度、斯特劳哈尔数、涡旋频率测量、温/压测量以及其它环节的系统不确定度分量和不确定度的合成。通过对测量系统不确定度的分析,提出了涡街流量计测量系统的改进方向以及涡街流量计的干标定问题,促进节能减排工作的进展。     

内燃机噪声测量不确定度

本文按《测量不确定度表示指南》和《测量不确定度评定与表示》规定的程序和方法,对引起内燃机噪声声功率级测量结果不确定度的因素(不包括声源本身的影响)及其累积效应进行不确定度分析与评定,旨在提高噪声测量结果的质量,促进降噪工作开展,并使测量不确定度评定在内燃机行业得到全面推广。     

A power-rating model for crystalline silicon PV modules

A model for the performance of generic crystalline silicon photovoltaic (PV) modules is proposed. The model represents the output power of the module as a function of module temperature and in-plane irradiance, with a number of coefficients to be determined by fitting to measured performance data from indoor or outdoor measurements. The model has been validated using data from 3 different modules characterized through extensive measurements in outdoor conditions over several seasons. The model was then applied to indoor measurement data for 18 different PV modules to investigate the variability in modeled output from different module types. It was found that for a Central European climate the modeled output of the 18 modules varies with a standard deviation (SD) of 1.22%, but that the between-module variation is higher at low irradiance (SD of 3.8%). The variability between modules of different types is thus smaller than the uncertainty normally found in the total solar irradiation per year for a given site. We conclude that the model can therefore be used for generalized estimates of PV performance with only a relatively small impact on the overall uncertainty of such estimates resulting from different module types.     

Validation of the Sandia model with indoor and outdoor measurements for semi-transparent amorphous silicon PV modules

This paper presents a set of indoor and outdoor measurement methods and procedures to determine the empirical coefficients of the Sandia Array Performance Model (SAPM) for a semi-transparent amorphous silicon (a-Si) PV module. After determining and inputting the total 39 parameters into the SAPM, the dynamic power output of the a-Si PV module was predicted. In order to validate the accuracy of using SAPM for simulating the energy output of the a-Si PV module, a long-term outdoor testing campaign was conducted. The results indicated that the SAPM with indoor and outdoor measured coefficients could accurately simulate the energy output of the a-Si PV module on sunny days, but it didn't work well on overcast days due to the inappropriate spectral correction as well as the equipment measuring error caused by the intense fluctuation of solar irradiance on overcast days. Specifically, all the errors between the simulated daily energy output and the measured one were less than 4% on sunny days. In order to achieve a better prediction performance for a-Si PV technologies, the SAPM was suggested to incorporate a more comprehensive spectral correction function to correct the impact of solar spectrum on overcast days in future.     

Evaluation of efficiency and degradation of mono- and polycrystalline PV modules under outdoor conditions

This paper presents the experimental results carried out over a period of years of several photovoltaic modules of two basic types, e.g. monocrystalline and polycrystalline, obtained from various sources. These panels were exposed outdoors under the climatic conditions of Bahrain. Our observations show that two of the “first generation” monocrystalline panels completely failed and severe corrosion developed. The rest of the panels show a degradation in efficiency, however polycrystalline modules show a greater drop in output.     

Estimation of the maximum power temperature coefficients of PV modules at different time scales

The maximum power temperature coefficients of a-Si modules are negative in indoor measurements, whereas the performance increases with module temperature in outdoor measurements. In order to resolve the discrepancy, we investigate the temperature coefficients of a-Si modules by two different methods corresponding to two different time scales. The results are that the temperature coefficient for a shorter time scale of several hours is negative, although the temperature coefficient for a longer time scale of seasons is positive. These results suggest that the discrepancy in temperature coefficient is partially caused by the effects of thermal annealing and light soaking. Therefore, the history of module temperature and received solar irradiance would be required for the correction of the performance of a-Si modules. In addition, we reveal that the effect of solar spectrum is also a contributory factor in the discrepancy.     

Outdoor performance of amorphous silicon and polycrystalline silicon PV modules

The daily watt-hour efficiency (η_Wh) and daily integrated output power (P_Wh) of the a-Si and poly-Si module have been used to examine the performances of both modules on the basis of two years' data accumulated at outdoor conditions. Results from the analysis of experimental data taken under incident solar energy higher than 3.0 kWh/m² per day show that the annual average of η_Wh of the a-Si module is about 95% and 92.5% of its efficiency at STC condition at the first and second year, respectively, while the values are nearly unchanged at about 89% for the poly-Si module. During a one year period, the average P_Wh of the a-Si and poly-Si module was about 60% and 56%, respectively, of their calculated output power at STC condition, so that the P_Wh for each watt-peak (W_p) of the maximum power of a-Si module is about 11% higher than that of the poly-Si module.     

晶体硅光伏组件的检测

我国有丰富的太阳能资源，太阳能光伏发电已不再仅仅用于小功率电源系统，而且广泛用于通信、交通、石油、农村电气化、民用产品等各个领域。1998年我国生产的太阳能光伏发电系统的主要部件——光伏组件产量只有2MWp左右，仅相当于世界总产量的1．3％，到2002年产量已达到100MWp左右，截至到2003年底在我国使用光伏组件装机的太阳能电站达到55MWp。保证太阳能光伏发电系统的质量不仅取决于系统的设计，     

Dynamic evaluation of maximum power point tracking operation with PV array simulator

This paper presents an innovative method to measure the dynamic control ability of maximum power point tracking for PV inverters under the condition of irradiance fluctuation. The PV array I–V curve simulator is a kind of indoor testing facility and easy to be adopted by industries. Basic functions are given by a specially designed PV array I–V curve simulator composed of the active power load. Most of the parameters are controllable by sophisticated software with capability of treating a lot of 1-s data for a very long period of time. In this paper, detailed structure of the equipment is described and test examples are also given by using a commercial PV inverter.     

The risk of power loss in crystalline silicon based photovoltaic modules due to micro-cracks

Micro-cracks in wafer based silicon solar cell modules are nowadays identified by a human observer with the electroluminescence (EL) method. However, the essential question of how the micro-cracks affect the PV module performance has yet to be answered. We experimentally analyze the direct impact of micro-cracks on the module power and the consequences after artificial aging. We show that the immediate effect of micro-cracks on the module power is small, whereas the presence of micro-cracks is potentially crucial for the performance of the module after artificial ageing. This confirms the necessity to develop the means of quantifying the risk of power loss in PV modules with cracked solar cells in their lifetime, in order to enable manufacturers to discard defective modules with high risk of failure while keeping modules with uncritical micro-cracks. As a first step towards risk estimation we develop an upper bound for the potential power loss of PV modules due to micro-cracks in the solar cells. This is done by simulating the impact of inactive solar cell fragments on the power of a common PV module type and PV array. We show that the largest inactive cell area of a double string protected by a bypass diode is most relevant for the power loss of the PV module. A solar cell with micro-cracks, which separate a part of less than 8% of the cell area, results in no power loss in a PV module or a PV module array for all practical cases. In between approximately 12 and 50% of inactive area of a single cell in the PV module the power loss increases nearly linearly from zero to the power of one double string.     

Early degradation of silicon PV modules and guaranty conditions

The fast growth of PV installed capacity in Spain has led to an increase in the demand for analysis of installed PV modules. One of the topics that manufacturers, promoters, and owners of the plants are more interested in is the possible degradation of PV modules. This paper presents some findings of PV plant evaluations carried out during last years. This evaluation usually consists of visual inspections, I-V curve field measurements (the whole plant or selected areas), thermal evaluations by IR imaging and, in some cases, measurements of the I-V characteristics and thermal behaviours of selected modules in the plant, chosen by the laboratory. Electroluminescence technique is also used as a method for detecting defects in PV modules. It must be noted that new defects that arise when the module is in operation may appear in modules initially defect-free (called hidden manufacturing defects). Some of these hidden defects that only appear in normal operation are rarely detected in reliability tests (IEC61215 or IEC61646) due to the different operational conditions of the module in the standard tests and in the field (serial-parallel connection of many PV modules, power inverter influence, overvoltage on wires, etc.).     

Application and validation of algebraic methods to predict the behaviour of crystalline silicon PV modules in Mediterranean climates

Predicting both PV module and generator performances under natural sunlight is a key issue for designers and installers. Five simple algebraic methods addressed to predict this behaviour in Mediterranean climates have been empirically validated. Firstly, the calibration in STC of all significant electrical parameters of both a monocrystalline and a polycrystalline silicon PV modules was entrusted to an accredited independent laboratory. Then, a 12-month test and measurement campaign carried out on these modules in the city of Jaén (Spain, latitude 38°N, longitude 3°W) has provided the necessary experimental data. Results show that (a) crystalline silicon PV module outdoors performance may be described with sufficient accuracy – for PV engineering purposes – only taking into account incident global irradiance, cell temperature, and using any one of two simple algebraic methods tried in this paper and (b) regardless the used method, poor results may be achieved if the PV specimens under study are not electrically characterised in STC prior to analysing their outdoors performance. Even so, the methods recommended in (a) perform best.