CC BY
11
(0:в) - оптимальная ежемесячная коррекция положения СМ; (@ф) - устройство слежения за солнцем (трекера); Ьфм - повышение эффективности работы станции которое было рассчитано по данной формуле:
Таблица. 3
Анализа эффективности СМ на основе двухкаскадного a-Si:H/nc-Si на широте Хартума и Санкт-Петербурга
Площадь = 1,43 м2, ц = 11% и Ррк = 157 Вт для СМ, П = 9,46% и Ррк = 135 Вт для устройства ФЭС при стандартных условиях измерения
Характеристики ФЭС Санкт-Петербург 59,9° широта, 30,3° долгота Хартум 15,6° широта, 32,5° долгота
0ф = 41° (0:ß) (®:ß) 0ф = 18° (0:ß) (®:ß)
Среднее значение Тт, °С 13,9 14,4 16,2 47 48,5 53,7
Среднее значение G(t), (Вт/м2) 251 267 324 567 613 778
Ш, Вт час/м2 3075 3271 3969 6662 7202 9142
РДГт, ^ г), Вт: А = 1м2 21,45 22,76 27,02 46,45 49,72 60,93
Pf(Tm, ^ г), Вт: А = 1,43м2 30,67 32,55 38,65 66,42 71,10 87,13
Е, кВт час: А = 1,43м2 0,375 0,398 0,473 0,780 0,835 1.023
Среднее значение КПД ФЭС, % 2,14 2,27 2,70 4,65 4,98 6,10
ЛQw, % - 6 26 - 7 31
AQw = (Ef/Ei) - 1 (9)
где Ei - вырабатываемая энергия при ßф.
Заключение. Основные результаты работы сводятся к следующему:
- Достоверность расчетов по программе PVGIS повышается при учете потерь мощности ФЭС на основе а-Si:H/nc-Si, возникающих из-за изменения температуры СМ.
- ßф составляет 18° для Хартума и 41° для Санкт-Петербурга.
- Высокая эффективность работы СМ на основе a-Si:H/nc-Si на территории Судана происходит за счет высокого и постоянного солнечного излучения в течение года. Благодаря этому Судан обеспечивает оптимальные условия для создания проектов, солнечных электростанций.
- Эффективность работы солнечной электростанции на основе двухкаскадных модулей a-Si:H/nc-Si на широте Хартума повышается на 7 % при оптимальной ежемесячной коррекции ß, и на 31 % при установке устройства слежения за солнцем (трекера).
Список литературы
1. Photovoltaic Geographical Information System. http://re .j rc.ec.europa. eu/pvgis/apps4/pvest.php#. European Commission. 2002 - 2013.
2. About Renewable Energy in the Republic of the Sudan. http ://www. rcreee.org/wp-
content/uploads/2013/07/RCREEE CountryProfile R E Sudan 2012 AR.pdf.pdf. (Regional Center for Renewable Energy and Energy Efficiency "RCREEE" - Sudan - 2013).
3. Energy Projects. http://www.wre.gov.sd/index.php. The Ministry of Water & Electricity - Sudan - 2013.
4. Температура воздуха. www.pogodaiklimat.ru. Климат Хартума и Санкт-Петербурга, 2004-2013.
5. E. Skoplaki, J.A. Palyvos. On the temperature dependence of photovoltaic module electrical performance: A review of efficiency/power correlations. Solar Engineering Unit, School of Chemical Engineering, National Technical University of Athens, 4 November 2008.
6. V.Jafari Fesharaki, Majid Dehghani, J. Jafari Fesharaki. The Effect of Temperature on Photovoltaic Cell Efficiency. International Conference on Emerging Trends in Energy Conservation. Tehran, Iran, 20-21 November 2011.
7. Kaneka - product. http://www.kaneka-solar.com/product/thin-film/pdf/U-EA.pdf. Texas U.S.A.
PHOTOVOLTAIC POWER STATION PROGRAM
Mirghani M. M.
Saint Petersburg State Electrotechnical University «LETI», St. Petersburg
ПРОГРАММНОЕ ОБУСПЕЧЕНИЕ ФОТОВОЛЬТАИЧЕСКИХ ЭЛЕКРОСТАНЦИЕЙ M. M. Миргхани
АННОТАЦИЯ
Программа PVPSP показала себя как надежный инструмент расчётов, кроме того обладающий интуитивно понятным интерфейсом и практичным выводом результатов, она позволяет рассчитать, как интенсивность солнечного излучения, падающего на любую точку планеты с разными углами в разное время года, общую площадь и количество панелей для солнечной электростанции, так и производительность солнечной электростанции (от 1 кВт до 250 мВт) в течение года с разными углами положения солнечных панелей.
Программа фотовольтаических электростанцией (PVPSP), Фотовольтаическая географическая информационная система (PVGIS), аморфные и нанокристаллические кремниевые солнечных элементов (a-Si:H/nc-Si).
Photovoltaic Power Stations Program PVPSP proved to intensity of the solar radiation incident on any point on the be a reliable tool for calculations also has an intuitive interface planet at different angles at different times of the year., the to-and a practical display of the results, it enables calculate the tal area and number of panels and productivity solar power
(from 1 kW to 250 mW) during the year with different angles of position of solar panels.
Photovoltaic power stations program (PVPSP), Photovoltaic Geographical Information System (PVGIS), radiation intensity, amorphous and nanocrystalline silicon solar cells (a-Si:H/nc-Si).
Introduction. The world has witnessed an unprecedented development in the XXI century in the field of solar cells industry. Between 2010 and this year in Russia was conducted many studies, which aims to raise the efficiency of solar cells and in this period the focus was largely on amorphous and nanocrystalline silicon solar cells (a-Si:H/nc-Si), due to the relatively high efficiency and rival for the rest of the other types in terms of economic cost. Indeed, the efficiency of these cells increased to 11.4 % [1]. It is expected to boost the efficiency to 14% by including polymorphous silicon (pm-Si:H) layers of the structure of the solar cells a-Si:H/nc-Si [2]. In the near future is counting on these cells in the construction of large PV power station (more than 1 MW). This trend according to the features of these solar cells enjoy beside the broad absorption spectrum characteristic compared to monocrystal-line silicon solar cells.
It is well know that performances of a given Photovoltaic (PV) station are strongly dependent on the climate conditions at the system setting. The most important parameters influencing these performances are the solar radiation impinging at the surface of the PV modules and the ambient temperature that effect losses from these modules.
There are many programs used in determining the productivity of PV stations. A famous of these programs is Photovoltaic Geographical Information System (PVGIS), which was create by the European Joint Research Centre. Advantage of this program is a long-term experience for monitoring and testing of various solar module according geographical location. However, this program does not take into calculate the effect of temperature on the performance of a-Si:H/nc-Si, which in recent years have gained widespread. As well as for other solar modules, does not calculate temperature change according to the change of the wind speed.
The aim of this paper is to write a program that calculates the productivity of solar PV power stations for all types of solar cells and for any area on the earth's surface, taking into consideration climate conditions such as the degree air temperature, wind speed and humidity.
Measurement of Meteorological Variables. The main key to extrapolate the data of solar power stations is to determine accurately meteorological data of the study area. There are two methods to get meteorological information, which are then use in calculations PV stations:
■ Ground measurements
■ Calculations based on satellite data
The first method is to install devices in the area where you want to study and these devices are registration of solar radiation data, temperature, humidity and wind speed.
Ground station measurements give the best results, but their number is limited, they are mainly in the cities and populated areas. Therefore, the adoption of data to be true near these stations and areas that are not located more than 5 kilometers.
The second method is calculations based on satellite data. There are a number of methods to estimate the solar radiation at ground level using data from satellites. Typically,
the satellites measure the light (visible or infrared) coming from the Earth. This light is mainly the light reflected from the ground or from clouds. The calculation of the solar radiation at ground level must therefore be able to take into account the radiation absorbed by the atmosphere as well as that reflected by clouds. Different types of satellites can be used to estimate solar radiation. Geostationary weather satellites take pictures of the Earth at short intervals (every 15 or 30 minutes) so have a very good time resolution. However, each pixel in the picture typically represents a rectangle a few km on each side, so the estimate of solar radiation for each pixel will be the average of such an area. Polar-orbiting satellites fly closer to the Earth, so the space resolution is better. However, they do not stay permanently above a particular area, so they are normally able to take only a couple of pictures a day of a given area [3].
The main advantage of satellite-based methods is that they give a fairly uniform coverage of large areas while ground stations are often very far apart. On the other hand, there are potential problems also with the satellite methods:
-I- Snow on the ground is a special problem for satellite methods, since snow will look very much like clouds in the satellite images. There are methods to overcome this problem, but the uncertainty is higher in areas with snow.
-I- In mountain areas one pixel may cover an area with strongly varying altitude. The solar radiation dependence on altitude is not well represented in the satellite-based calculations.
-I- When the sun is very low in the sky the calculation from satellite data becomes very difficult. This can cause problems, in particular in winter at high latitudes. The quality of satellite-based estimates must be checked by comparison with high-quality ground station measurements.
Photovoltaic Power Stations Program (PVPSP) proposes a scientific solution to estimate the daily solar radiation accurately value. The solution is to make a correction value of solar radiation through:
1. Calculate the daily solar radiation value theoretically from equations (Variables here are Location, Altitude, Time and Date).
2. Registration temperature, humidity and wind speed data from ground stations or satellites.
3. Calculate the losses of theoretical solar radiation according to three variables (air temperature, humidity and wind speed), where the change in the value of any of this data is accompanied by a change in the other data values as follows:
~ Wind speed function in the temperature [(Vair) = f(T)];
~ Temperature function in humidity [(Tair) = f(H)];
~ Solar radiation functions in humidity and wind speed [(R) = f(H, Vair)].
On the basis of the above information it can be said that:
I. The wind speed increases the possibility of result dust formation in the atmosphere and thus deficiency the amount of beam solar radiation connecting to the earth's surface
II. Increased humidity lead to increase ratio of absorption in layers of the atmosphere and increase the percentage reflection beam of solar radiation return back to space.
Some basic equations used in PVPSP. The equation of time (EoT) (in minutes) is an empirical equation that corrects for the eccentricity of the Earth's orbit and the Earth's axial tilt:
EoT = 9.87 sin(2B) - 7.53 cos(B) - 1.5 sin(B) (1)
Where
360 , B = 365 (d-81)
(2)
where d is the number of days since the start of the year. The declination angle, denoted by 5, varies seasonally due to the tilt of the Earth on its axis of rotation and the rotation f [CoEibiTHfl Equations]
of the Earth around the sun. If the Earth were not tilted on its axis of rotation, the declination would always be 0°. However, the Earth is tilted by 23.45° and the declination angle varies plus or minus this amount. Only at the spring and fall equinoxes is the declination angle equal to 0° [4].
The declination angle can be calculated by the equation:
S = sin-1(sin(23.45°) sin(B)) (3)
Figure 1 illustrates how to write the previous three equations in the program code.
- f Load
For Day = 1 To DayArray.Length - 1 DayArray(Day) = Day B = (360 / 365) * (Day - SI) BRad - (Hath.PI / 1B8) * B
E0T = (9.S7) * (Hath, sill (2 * BRad)) - (7.53) * Hath .Cos (BRad) - (1.5) * Math. Sin ((BRad)) kronikaRad - ■■1ath.Asin(,'lath.Sin(23.45 * 'lath. PI / 1SG)) * -lath. Sin (BRad) kronikaDeg - kronikaRad * 1S0 / Hath.PI Next Day
Figure 1. Fragment of code PVPSP
Temperature dependence of the solar module on the air temperature and the radiation intensity is defined as follows:
Tm = Ta + (TNOCT - 20)
G(t) gNOST
= Ta + [Kt,
NOST
■ G(t) (4)
E = ((G x t)/G°) • Ppk • nf = (lOOo) ^ P
Wherein the temperature of the solar module at an open circuit when the ambient temperature 20 °C; GNOST -intensity of 800 W / m2 at a wind speed of 1 m / s; KT, NOST - the conversion coefficient of optical radiation in temperature.
The average daily value of electricity production by PVPS was calculate according to this formula:
pk • nf (5)
where E in kilowatt hour (kWh) unit, which is a measure of the amount of energy consumed or produced; t - time of a solar day; Hd - the average value of the sum of the intensity of radiation per hour per square meter for a solar day (Wh / m2).
Contents of the program and explain interfaces. PVPS program written in Visual Basic (2013), which is widely used in solving mathematical calculations and researches. PVPSP is designed for scientific and commercial purposes. Interfaces and reporting program in English, Russian and Arabic language.
The PVPSP can be calculated:
The intensity of solar radiation incident on any point on the planet at different angles at different times of the year;
Loss of solar radiation due to angular reflectance effects;
The average temperature of any solar panel during the year due to data on air temperature, solar radiation and wind speed;
The number of solar panels which will be used in solar power stations;
The total area of panels for solar power stations; Productivity of solar power stations (from 1 kW to 250 mW) during the year with different angles of solar panels positions (by the horizon, latitude, selected angle and monthly correction angle position of solar panels depending on changes in azimuth for each month).
The first interface for entry and exit from program. Figure 2 illustrates the first interface.
Figure 2. The first interface PVPSP
The second interface for data entry and view the results.
Data entry for the program in three stages:
1. Geographical location data, which contain Latitude, Longitude & Altitude. These data can be obtained from the GLD link with a blue color in the second interface (Figure 3 - a).
2. Solar station data, which contain Power, efficiency & TNOST of solar panel. This information is located on the backside of the solar panel. In solar radiation data, it also contain information about selection angle of solar panel and productive power station required.
3. Meteorological data, which contain Air temperature, Relative humidity & Wind speed. This information is also can be obtained from the MD link. Through this interface can access to the third interface, which contains information about the program and how to use the program.
Figure 3 represents a picture of the second interface program before entering data and after entering data for St.Peterburg City - Russia, and for to productive power station (1kW, 1MW).
File Help
se.oa.sois
381781.153 242806.220
Ortohrt-
The ittrig» printer
0 2M 0.097 0.017 0 540
117196 479 44808 404 21SSJ 105 250000 000
T of шпм« per dir » ri» installation of uilir p>uli jîcontins to ih« monthly arimnth
ГЪс qaantirv of salar panc-k 447499.1 panels
Tb« total area of solar pa*«Jt 63*703.2 a'
The production photovoltaic power >UI»os 2500*0 kWh
latitude (') 59.938
Nominal pcwer ol me s<
Produktive power roqiiirod
Geographical location data
S«ilnr slHliuiis ГУм1»
Norr>nal etneerey c< Ih» setar panel (*)
Altitude atmre sen fcviK (m>
T < Nuninal upefali'iy
oflhescta'pnnd ГС)
Selection inctnalion angle of solar ponci acccnlng to the horizontal (*>
Fo- 4w soultt of the ctxalst 40 For ihe north ofte eqjalu
.Month The »vcrag« reiaperanre of the uiir |uul (С1) Prnlarnl by ob« solar panel Distn <kWht stat» na during the vcar (kWh)
Jwvwry -9 4 01)98 4)911 141
F<tnu»4 « 0.235 105373.347
Marek 1.3 0.478 214021 062
April 12 4 0 777 347624 778
Мшу 22.0 1.035 463376.391
Jme 28 6 1.156 5I711S.114
ht) 31 3 1 064 476262 233
Ацца; 27.1 0.830 371430.178
September 17 S 0.550 246130 753
October 76 0291 130226 587
November -2.9 0.124 55526J50
Decent» 9 0 0 065 2S995 565
Yc« 100 0559 250000 C00
Motoorologir.il tfcrt.i
Rebitive hurrority (%)
About IKc ptogiam
tntcr new oato
All rirf*s»«avedC' 2014 - 2015. Montana Mb shea
74 яп Г: 04-Ы2 lui l-eh i /»H Mai 31
ы: W5 F23 r-.
42 Apr 108 Mir» 155 Jun 708 Ар» £23 May Gl A Jun
J.J 44 45 S ■гам 15.» мал 1- -13 1 1 ; 113 7 ■ ¡li- IP" SnnrÉ «4 И 5 и s гп^^ш 1 □S M
1/8 -Xt "'s 17 S ICS Aus H 10 b See 1104 PF" P - ri 1 U » ■ S) 7 Aug =S 1 <04 Itoo 75.3 Зеэ 757
?9 Feb 29 Mai
Apr 29 ttev 29
I
Fxport the repert as an HIMLMe
Figure 3. The second interface PVPSP
The report of PVPSP. The program generates a report in HTML file with the desired graphics for print and the ability to insert the script report in websites.
Figure 4 illustrates the report of PVPSP for St.Peterburg City - Russia (1kW - station based on a-Si:H/nc-Si panels). The report contains seven Pages with seven tables and eight graphics.
Photovoltaic power station program (PhVSP)
Repart on the geographical location
(latitude: 59.938 Longitude: 30.339. Altitude: U above sea level)
Figure 1. The average air temperature during the year
Л Ê » 5
Month The average air temperature (C) Humidity (•/•) Wind speed (m's)
January ) -74 84 4 3
February -74 82.7 29
March -2.9 79,3 2.9
Apnl 42 708 1 3
May 10.8 62.3 29
June 15.5 63.8 2.9
July 178 66 28
August 158 69.7 29
September 10.5 75.3 3
October 48 82.3 3.1
November -2 844 29
December -6.4 84.8 2.9
Year 44 75.5 2 9
Figure 4. The the report of PVPSP
Conclusion. The main results are summarized as follows:
4- Can be explore any point on the planet from the equator to the north pole and the south including land and water.
4- Convenient interface, in which the maximum reduced data entry errors for fair calculation.
4- In comparison with the program PVGIS, PVPSP gives more accurate results of solar power capacity by determining the temperature of the solar panel is
dependent on a number of factors (solar radiation, the angle of incidence of solar radiation, wind speed).
4- report is generated in the form of an HTML file which enables insert the script report in websites.
References
1. В.П. Афанасьев, Е.И. Теруков, А.А Шерченков. Тонкопленочные солнечные элементы на основе кремния. 2-е изд. СПб.: Изд-ов СПбГЭТУ «ЛЭТИ», 2011. 15 с.
2. Бадрелдин-Миргхани М.М., Семенов А.В., Терен-тьева В.Н., Теруков Е.И., «Оптические и фотоэлектрические свойства тонкопленочных пленок полиморфного гидрогенизированного кремния» // Сборник трудов II Всероссийской научной конференции «Наноструктурированные материалы и преобразовательные устройства для солнечной энергетики 3-го поколения», Чебоксары. 2014. С.76-79.
3. Photovoltaic Geographical Information System. http ://re .jrc.ec. europa.eu/pvgis/, European Commission. 2002 - 2014.
4. Photovoltaic Education Network. http://pve-ducation.org, 2014.
РАСЧЕТ ЭЛЕКТРОДИНАМИЧЕСКИХ СИЛ В ПЛОСКОМ ПОЛУКОЛЬЦЕ С ТОКОМ
Буров Анатолий Викторович
доктор технических наук, профессор, ВУНЦВМФ «ВМА», г. Санкт-Петербург,
Попов Юрий Игоревич,
кандидат физико-математических наук, доцент, СПбГЭТУ «ЛЭТИ», г. Санкт-Петербург
Рискнок 1. Плоское полукольцо с током
Рассмотрим взаимодействие токов в проводнике в форме полукольца, вырезанного из тонкого листа немагнитного металла толщиной J А (Рис. 1).
Внутренний радиус полукольца обозначим через
a
внешний
через
b
а их отношение
a < 1 b _
через мала
^ . Будем считать, что ширина полукольца (Ь а)
ь
по сравнению с его внешним радиусом и , т.е. значение
(у ' ЛП Ъ
^ достаточно близко к единице, и ш . При наших предположениях можно считать, что линии тока в полукольце параллельны его плоскости и представляют собой полуокружности.
Для определения величины Р суммарного взаимодействия токов в полукольце обратимся к общему выражению (7) работы [1, с. 587], рассматривая тот случай, когда ток, протекающий в полукольце, а также форма и размеры самого полукольца не зависят от времени. Тогда в формуле (7) работы [1, с. 587] можно положить
d^k dVk, d^n dVn, , Jn Jn
откуда F - M
4n
J dVn J dVk
Jn X ( Jk X Rkn )
Rkn
где
V V , (1)
У — область пространства, занимаемая полукольцом.
Рассмотрим два произвольных элемента объема
проводника к и п. Введем цилиндрическую систему координат, поместив начало координат в центре полукольца так, чтобы полукольцо располагалось в плоскости XOY симметрично оси ординат (Рис. 1). Тогда
=рк(1ркЛфкА, йУп =pndpndфnk
dVn
Радиус-векторы элементов объема
Rk R
обозначим соответственно через k и
n
откуда
Rk = Рк(i ' cospk + j • sin^k), Rn =Pn(i • cos^n + j • sinÇn)
