| 摘要(英) |
This thesis developed an apparatus for measuring the offset angle of sun-tracking system with CCD camera and performed the outdoor tests of two photovoltaic (PV) systems which are controled by closed-loop and hybird sun-tracking (combine the detection of short-circuit current and sun-position calculation), respectivily. Monitoring data including offset angles and PV power performance.
CCD sensor is a discrete element structure based on the matrix elements to record images. This thesis used LabVIEW to develop an image processing algorithm to acquire the image profile, and then find out the centroid of image. Image processing consists of four parts: acquiring of sun images, image threshold processing, target filtering, and calculating centroid position.
Clustering-threshold method is better than the fixed-threshold binary approach in condition of varying light attenuation/scattering on outdoor testing. Comparing with centroid approach and edge-detection method for distinguishing sun images was carried out. On clear days, the average of offset angles ranging from 0.008o-0.01o, and values of 0.02o-0.05o was obtained on cloudy days. Results with the edge-detection method shown that in the case of cloud covering on sunlight wouldn’t degrade its accuracy. Thus the edge-detected method is better than the centroid method. Position sensitive device (PSD) technique is adopted to validate CCD technique for its applicability. The former has high accuracy and transmission, and the latter can correct local cloud covering on sunlight by image processing.
Field testing with CCD for monitoring the close-loop and hybrid sun-tracking found that the former has an average of offset angle of 0.147o on a six-day period and the average power output of 1226 W (total electricity on six days is 73.73 kWh). The hybrid sun-tracking has an average of offset angle of 1.291o on a five-day period, and the average power output of 1291 W (total electricity on six days is 68.9 kWh). Most of offset angles of the former are less than 0.3o. While the latter mainly using perturbation to detect the short-circuit current of PV module, which significantly being affected by solar radiation, deformed by gravity when finding maximum power point where offset angle is not small and limited test period (only full 6 days measurement). Thus the hybrid sun-tracking has large offset angles ranges up to 3.5o. Further long time monitoring of PV electrical performance is needed to fully assess the characteristics of sun-tracking based on short-circuit current. Although the short-circuit current tracking accuracy is less than the sun-tracking sensor, yet for assessing the performance of PV system, electricity is the ultimate factor. Thus, the hybrid sun-tracking with the short-circuit current algorithm is a practical and effective sun-tracking method.
|
| 參考文獻 |
行政院原子能委員會（2011），太陽光發電影像追蹤技術研發，委託研究報告。
陳宏鑫（2011），以PSD開發混合式追日控制與直射日照量測方法，國立中央大學能源工程研究所碩士論文。
曾英瑞（2011），高精度影像追蹤技術之研發應用於高聚光型太陽能供電系統，國立成功大學航空太空工程研究所碩士論文。
周建仁（2011），太陽電池短路電流法追日控制器之研發，國立中央大學機械工程研究所碩士論文。
劉智維（2010），以指向誤差修正技術應用在追日精度改進，國立中央大學能源工程研究所碩士論文。
陳麒峯（2010），追日偏差量測技術開發與聚光太陽光電系統之實測，國立中央大學能源工程研究所碩士論文。
張智凱（2008），被動式雙軸太陽追蹤器之追控系統開發，國立中央大學能源工程研究所碩士論文。
Arturo M.M. and Alejandro G.P (2010) “High–Precision Solar Tracking System,” Proceedings of the World Congress on Engineering 2010 Vol. II WCE 2010, June 30 – July 2, 2010, London, U.K.
BASLER (2011) “Scout users_manual,” BASLER.
Chong, K.K., Wong, C.W. (2009) “General formula for on-axis sun-tracking system and its application in improving tracking accuracy of solar collector,” Solar Energy 83:298–305.
Chong, K.K., Wong, C.W., Siaw, F.L., Yew, T.K., Ng, S.S., Liang, M.S., Lim, Y.S., and. Lau, S.L. (2009) “Integration of an on-axis general sun-tracking formula in the algorithm of an open-loop sun-tracking system,” Sensors 9:7849-7865.
Cucumo, M., Kaliakatsos, D., Marinelli, V. (1997) “General calculation methods for solar trajectories,” Renewable Energy 11:223-234.
Delta-T (2012) http://www.delta-t.co.uk/
DERlab (2011) “DERlab technical guidelines on long-term PV module outdoor test 100 – 01,” DERlab.
Donato V., Stefano B., Massimiliano O., Marco S., Antonio P., Giuliano M. (2010) “Measurement of sun-tracking accuracy and solar irradiance through multispectral imaging,” Optics for Solar Energy (OSE), Tucson, AZ, Solar Concentrator Characterization (STuA).
Davis, M., Lawler, J., Coyle, J., Reich, A., Williams, T. (2008) “Machine vision as a method for characterizing solar tracker performance,” GreenMountain Engineering, LLC, 33rd IEEE Photovoltaic Specialists Conference.
Duffie, J.A., Beckman, W.A. (2006) Solar Engineering of Thermal Processes, 4th Ed. New York: John Wiley & Sons.
Green M.A., Emery K., Hishikawa Y., Warta W., Dunlop E.D. (2011) “solar cell efficiency tables (version 38),” Prog. Photovolt: Res. Appl. 19:565-572.
Kelly N.A., Gibson T.L. (2011) “Increasing the solar photovoltaic energy capture on sunny and cloudy days,” Solar Energy 85:111–125.
Koussa M., Cheknane A., Hadji S., Haddadi M., Noureddine S. (2011) “Measured and modelled improvement in solar energy yield from flat plate photovoltaic systems utilizing different tracking systems and under a range of environmental conditions,” Applied Energy 88:1756–1771.
National Instruments (2007) “NI Vision Concepts Manual,” National Instruments.
Nijegorodov N., Devan K.R.S., Jain P.K., Carlsson S. (1994) “Atmospheric transmittance models and an analytical method to predict the optimum slope of an absorber plate, variously orientated at any latitude,” Renew Energy 4:529–43.
Reda, I., Andreas, A. (2008) “Solar position algorithm for solar radiation applications,” NREL/TP-560-34302.
Roth P., Georgiev A., Boudinov H. (2004) “Design and construction of a system for sun-tracking,” Renewable Energy 29: 393–402.
Thousand Oaks Optical (2012) http://www.thousandoaksoptical.com/index.html
|
[Endnote RIS 格式]
[相關文章]
[文章引用]
[完整記錄]
[館藏目錄]
[檢視]
plurk
funp
live
udn
HD
myshare
netvibes
friend
youpush
delicious
baidu
Google bookmarks
del.icio.us
hemidemi
facebook
twitter
google
reddit