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921.
在光伏并网发电过程中,为了不影响电网的电能质量,逆变器输出并网电流谐波分量应该满足相关的并网标准。文章提出了一种基于阻抗分析的方法,分析了光伏并网逆变器与含背景谐波电网之间的谐波交互影响问题。光伏并网所引起的谐波谐振问题产生的根本原因是逆变器等效输出阻抗和电网等效阻抗在并网公共连接点(POC)处存在阻抗交点,且在交点位置阻抗和值最小,此时并网电流幅值将明显增大,即产生谐波谐振现象。为了分析这一问题,本文建立逆变器的诺顿等效模型,推导逆变器的等效输出阻抗表达式,并基于光伏并网谐波电压、电流的最大限值及谐波谐振条件,分析逆变器等效输出阻抗的合理取值范围。在此基础上,采用PI控制、准PR控制两种不同的控制方法调节逆变器等效输出阻抗,有效的抑制谐波,并避免谐波谐振现象的产生。通过仿真实验,验证了本文方法的有效性。 相似文献
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923.
Modeling of Nonlinear Magnetizing Characteristics of Pole Transformer for Analyzing Islanding Prevention of Photovoltaic System 下载免费PDF全文
Yoshiaki Yoshida Hirokazu Suzuki Koji Fujiwara Yoshiyuki Ishihara 《Electrical Engineering in Japan》2014,188(3):46-55
With increasing penetration of distributed generators such as photovoltaic (PV) systems in distribution systems, it is very important to quickly detect islanding caused by power system faults in order to assure electrical safety. We have developed a nonlinear magnetizing characteristics model of pole transformers for use in analyzing islanding prevention in PV systems. Basic experiments on the islanding detection were performed for verification of the proposed model. Analytical results obtained by the proposed model agreed well with experimental results. 相似文献
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926.
Santolo Daliento Vincenzo d'Alessandro Pierluigi Guerriero Orlando Tari 《Progress in Photovoltaics: Research and Applications》2015,23(2):194-200
In this paper, the selective illumination approach is adopted to separately extract the shunt resistance of the individual subcells belonging to a tandem cell. The method relies on simple theoretical considerations and is based on the measurement of the current–voltage characteristic of the tandem cell by alternately keeping one of the subcells under dark conditions. Numerical simulations are employed to support the reliability of the technique, which is experimentally tested on micromorph devices deposited onto glass covered by a V‐shaped transparent conducting oxide and subject to different thermal treatments. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
927.
Helmut Mckel Gabriel Micard Kenneth Varner 《Progress in Photovoltaics: Research and Applications》2015,23(2):135-149
A theoretical analysis of the power loss and series resistance of the front side emitter in silicon solar cells is presented. Existing 1D models (infinitely long finger) and 2D models (including the effect of busbars) of emitter series resistance contribution are extended to the case of selective emitters. The general case of different current densities for both emitters in the selective emitter scheme is considered in these extensions. The resulting models depend on the individual sheet resistances and current densities in both emitters and the device's overall grid geometry. The models are corroborated by finite element simulation of the potential in the emitter. An excellent agreement is found between the analytical models, and the simulations for a wide range of sheet resistances typically encountered in silicon solar cells. Grid simulations using the 2D model are applied to solar cells with selective emitters, where the width of the low‐resistive emitter was varied. The simulations demonstrate that the 2D model can explain the absolute change in fill factor observed in these cells. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
928.
Joao Gari da Silva Fonseca Junior Takashi Oozeki Hideaki Ohtake Takumi Takashima Kazuhiko Ogimoto 《Progress in Photovoltaics: Research and Applications》2015,23(10):1203-1218
The development of methods to forecast photovoltaic (PV) power generation regionally is of utmost importance to support the spread of such power systems in current power grids. The objective of this study is to propose and to evaluate methods to forecast regional PV power 1 day ahead of time and to compare their performances. Four forecast methods were regarded, of which two are new ones proposed in this study. Together, they characterize a set of forecast methods that can be applied in different scenarios regarding availability of data and infrastructure to make the forecasts. The forecast methods were based on the use of support vector regression and weather prediction data. Evaluations were performed for 1 year of hourly forecasts using data of 273 PV systems installed in two adjacent regions in Japan, Kanto, and Chubu. The results show the importance of selecting the proper forecast method regarding the region characteristics. For Chubu, the region with a variety of weather conditions, the forecast methods based on single systems' forecasts and the one based on stratified sampling provided the best results. In this case, the best annual normalized root mean square error (RMSE) and mean absolute error (MAE) were 0.25 and 0.15 kWh/kWhavg, respectively. For Kanto, with homogeneous weather conditions, the four methods performed similarly. In this case, the lowest annual forecast errors were 0.33 kWh/kWhavg for the normalized RMSE and 0.202 kWh/kWhavg for the normalized MAE. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
929.
P. Espinet‐Gonzlez C. Algora N. Núez V. Orlando M. Vzquez J. Bautista K. Araki 《Progress in Photovoltaics: Research and Applications》2015,23(5):559-569
A temperature accelerated life test on commercial concentrator lattice‐matched GaInP/GaInAs/Ge triple‐junction solar cells has been carried out. The acceleration of the aging has been accomplished by subjecting the solar cells at temperatures markedly higher than the nominal working temperature inside a concentrator, and the nominal photo‐current condition (820 X) has been emulated by injecting current in darkness. Three tests at different temperatures have been carried out. The failure distributions across the three test temperatures have been fitted to an Arrhenius–Weibull model. An Arrhenius activation energy of 1.59 eV was determined from the fit. The reliability functions and parameters of these solar cells at two nominal working conditions (80 and 100 °C) have been obtained. In both cases, the instantaneous failure rate function monotonically increases, that is, the failures are of the wear‐out kind. We have also observed that the reliability data are very sensitive to the nominal temperature condition. In fact, at a nominal working condition of 820 X and 80 °C, assuming that the concentration module works 5 h per day, the warranty time obtained for a failure population of 5% has been 113 years. However, for a nominal working condition of 820 X and 100 °C, the warranty time obtained for a failure population of 5% has been 7 years. Therefore, in order to offer a long‐term warranty, the working temperature could be a key factor in the design of the concentration photovoltaic systems. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
930.
R. Timmreck K. Leo M. Riede 《Progress in Photovoltaics: Research and Applications》2015,23(10):1353-1356
Recently organic tandem solar cells with record efficiency had been shown comprising identical absorber materials in both subcells. Such structures pose new challenges for characterization. The standard test methods for measuring spectral response of tandem solar cells can not be applied. The standard procedures demand for different bias illumination during measuring spectral response allowing to select the subcell being current limiting. With subcells comprising identical absorber materials, thus having identical absorption spectra, such a selection is not trivial. In this paper, we show that with the help of detailed optical simulations of such tandem organic solar cells, their characterization is possible, and we apply the proposed method to a sample structure. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献