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1、<p><b> 附 錄</b></p><p> Solar Energy Copyright Elsevier Science </p><p> DATA SAMPLING SPEED VERSUS ENERGETIC MEASUREMENT ERRORS OF IRRADIATION MONITORING IN PHOTOVOLTAIC
2、 </p><p> Tokyo University of Agriculture and Technology,2-24-16,Nakamachi, Koganei-shi, Tokyo 184, Japan.(Communicated by GERARD WRIXON.)</p><p><b> Abstract:</b></p><p
3、> To measure solar irradiation and photovoltaic array output energy a measuring accuracy cannot be guaranteed unless the data sampling interval is appropriately selected.From this viewpoint,actual irradiance has been
4、 measured by comparatively high speed sampling of l-4s for 44 months and the daily errors of the numerical integral have been estimated for various step sizes.Approximation formulae of the error versus the step size have
5、 been statistically obtained as well as their probability density </p><p> Introduction:</p><p> In a photovoltaic system the input solar energy has a basic day-and-night cycle and an uncertai
6、n, time varying factor caused by meteorological conditions.When a measurement is performed to obtain long-term performance parameters such as irradiation,the amount of generated energy,etc.,the accuracy of the measuremen
7、t may not be maintained if the sampling speed of data acquisition is decided regardless of the fluctuating rate of solar radiation.</p><p> Since simplified measurements may have to be adopted in the future
8、 with the spread of photovoltaic systems,some instructions must be clearly prepared as a system monitoring standard.The author presents an analysis of this need.</p><p> For this purpose, actual irradiance
9、profile has been measured by comparatively high speed sampling for 44 months at the Electro- technical Laboratory in Tsukuba Science City(Kurokawa and Mine,1989;Kurokawa,1994).By using these data, the daily errors of num
10、erical integration have been evaluated for various time step sizes.Then,the errors for each step size have been analyzed for a certain term to obtain statistical parameters such as standard deviation 0 and average value.
11、Approximation formulae h</p><p> Data Acquisition:</p><p> In order to know the true integral of irradiance profiles,original irradiance data were taken at a comparatively high speed sampling
12、rate for 44 months from September 1986 to April 1990 at Tsukuba Science City.The city is located 60 km north of Tokyo and its climatic conditions seem to be ordinary as far as Japan is concerned.</p><p> Me
13、asuring equipment used is illustrated in Fig.1.Noises,which may be generated in signal conditioners,were also suppressed very carefully by using an isolation amplifier and electronic filter.In addition,a digital averagin
14、g technique synchronized with the utility grid frequency was adopted and drastically decreased the noise level.More than 100 data were sampled and averaged for just 40ms,which corresponds to 2 cycles of the frequency.Thi
15、s becomes one sample of raw data for this study.</p><p> Total data acquisition flow is illustrated in Fig.2.The normal raw data sampling period was 1s but it was made longer,up to 4s,in case of a slower fl
16、uctuating speed of the irradiance to reduce data volume.Daily data were stored in a 2HD disk for every day.</p><p> By applying the trapezoidal rule to the measured irradiance data, typical examples of whic
17、h are shown in Figs3(a) and 4(a),the integrated value of irradiance,i.e.irradiation, si is given by.</p><p> The integrating interval is indicated by h.Iteration of eqn(1) gives as daily integral of Si unti
18、l ti=sunset.</p><p> The various intervals are denoted as hj for j=l-60.The sampling interval of the original data is ho.The range of hi corresponds to 10s to 2h logarithmically as shown in Table 1.S,and Sj
19、 are given as S for h=ho and h=hi,respectively.Then,per cent integration error,ej is defined by.</p><p> The statistical values obtained for a comparatively short term are apt to show some irregularity in t
20、he trends of standard deviations as presented in Fig.6.However, it is observed that the overall results for the whole 44 months gave enough smoothness as shown in Fig.9.Therefore, the 44 month results are to be studied a
21、s described below.</p><p> By using the data in Fig.9,approximation formulae were formed.As shown in Figs 10 and 11,the relationship showing and cs versus hj is determined by.</p><p> To obtai
22、n enough precision for both smaller h regions and larger ones,two-region approximation was adopted.For example,it gives m=0.0315 and d=0.220 for h=60 and their ratios to statistical data are 1.07 and 0.980,respectively.A
23、lthough the former looks slightly large,the data of m contain larger irregularities.They seem to be a reasonable approximation for data smoothing.</p><p> Probability:</p><p> As a tentative c
24、onclusion of the preceding statistics,it is understood that the standard deviation of integration errors is mostly a noteworthy factor for determining an appropriate integration interval.However,its probabilistic meaning
25、 is not precisely known so far.This section studies it.</p><p> The frequency of the error classes covering +40 at respective intervals has been plotted as histograms as shown in Figs 12-14.Figure 12 is giv
26、en for h=60s,Fig.13 for h=600s and Fig.14 for h=3600s.From these figures,it is supposed that their distribution shapes are fairly similar in all intervals.Therefore,each histogram is superimposed by normalizing the integ
27、ration errors with each standard deviation 6.This result is given as a histogram inFig.15.The Gaussian distribution is also drawn in the s</p><p> 在光伏誤差輻射監(jiān)測能量測量的數(shù)據(jù)與采樣速度</p><p><b> 耿介黑川&l
28、t;/b></p><p> 東京大學(xué)農(nóng)業(yè)和科技,16年2月24日Nakamachi</p><p> 小金井市,東京184,日本</p><p><b> 摘要:</b></p><p> 為了測量太陽輻射和光伏陣列輸出能量,除非數(shù)據(jù)采樣間隔是適當(dāng)選擇,否則測量精度無法保證。從這個角度看,實際輻照已被1-
29、4秒的比較高的速度采樣測量44個月,用數(shù)值積分的每日誤差估計各種步長。用逼近公式的誤差與步長以及統(tǒng)計學(xué)獲得其概率密度函數(shù)覆蓋±4σ。最后,諾模圖是決定一個適當(dāng)?shù)牟蓸娱g隔??偨Y(jié)的例子表明,偏離誤差超過±1%的組件可以為每1個月或6個月發(fā)生一次,如果選擇步長為105或65.5s,則總誤差變?yōu)?0.0485±1%,或-0.0336±1%,其中包括根據(jù)筑波測得的數(shù)據(jù)平均誤差分量。版權(quán)1996愛思唯爾網(wǎng)絡(luò)科
30、技有限公司。</p><p><b> 引言:</b></p><p> 在太陽能光伏系統(tǒng)中輸入的太陽能有一個基本的晝夜周期和一個不確定的,隨時間變化氣象條件造成的的因素。當(dāng)測量是獲得長期作為輻射度,產(chǎn)生的能量等性能參數(shù),如果數(shù)據(jù)采集的采樣速度是決定于太陽能的輻射,而不是太陽能的波動率,測量精度可能無法維持。</p><p> 由于簡化了
31、測量可能要通過在未來光伏發(fā)電系統(tǒng)的傳播,一些指令必須明確準備作為一個系統(tǒng)的監(jiān)測標準。作者提出這方面的需求的分析。 為此,實際輻射譜在筑波科學(xué)城電工技術(shù)實驗室用比較高的速度采樣,用了44個月(黑川和煤礦,1989年;黑川紀章,1994年)來測量。通過使用這些數(shù)據(jù),數(shù)值積分的日常錯誤已被評估為不同的時間步長。然后,每一步的大小誤差都進行了分析,以獲得一定期限,如標準偏差0和平均值的統(tǒng)計參數(shù)。近似公式也已表達這些值和步長之間的關(guān)系。此
32、外,誤差的概率密度函數(shù)輪廓也已估計。最后,通過應(yīng)用的近似公式和概率密度函數(shù),諾模圖是確定最大允許步長,以保證監(jiān)測精度。</p><p><b> 數(shù)據(jù)采集:</b></p><p> 為了了解真正的輻照型材的組成,原輻射數(shù)據(jù)均在一個比較高的速度采樣率采樣,用時44個月,從1986年9月至1990年4月在筑波科學(xué)城。科學(xué)城位于東京以北60公里,其氣候條件對日本來說是
33、普通的城市。</p><p> 測量設(shè)備使用說明圖1噪音,可能產(chǎn)生的信號調(diào)理,也非常仔細地進行抑制,使用隔離放大器和電子過濾器。此外,通過與電網(wǎng)頻率同步數(shù)字平均技術(shù),大幅降低噪音水平。超過100多個數(shù)據(jù)采樣,平均只有40毫秒,這相當(dāng)于2個周期的頻率。這將成為本研究的原始數(shù)據(jù)的一個樣本。</p><p> 總數(shù)據(jù)采集流程如圖2所示。正常的原始數(shù)據(jù)采樣周期從1秒提高到4秒,可用于輻射波動速
34、度較慢的情況下減小噪音量。每日數(shù)據(jù)存儲在每天的2HD磁盤。</p><p><b> 定義及統(tǒng)計:</b></p><p> 通過測量輻射數(shù)據(jù)應(yīng)用梯形法則,其中典型的例子是在圖3(a)和4(a)所示,集成的輻射值,即照射,是由不同的時間間隔為表示,j=1-60。原始數(shù)據(jù)的采樣間隔是。范圍相當(dāng)于10秒至2小時,對數(shù)如表1所示。</p><p>
35、; 一個設(shè)置上繪制的參考期的散點圖,圖5的一個例子所示。然后,平均值m,每個間隔的標準偏差σ的計算。如圖6計算的例子,對應(yīng)圖5。集成一個特定的時間間隔,h=60s,在圖7,這些統(tǒng)計結(jié)果用了44個月。這些每年還表示在圖8上。他們觀察到任何明顯的季節(jié)性趨勢不能。因此,本文進一步研究只涉及到整個學(xué)期。</p><p> 一個比較短的時間內(nèi)獲得的統(tǒng)計值,容易出現(xiàn)在一些不規(guī)則的趨勢圖6的標準偏差。然而,據(jù)觀察,整個44
36、個月的整體成績給予了足夠的平整度,如圖9。因此,44個月的結(jié)果是要研究如下所述。</p><p><b> 概率</b></p><p> 由于前面的統(tǒng)計數(shù)據(jù)的初步結(jié)論,據(jù)了解,集成誤差的標準差主要是一個值得注意的因素,確定一個適當(dāng)?shù)恼祥g隔。但是,它的概率的意義不正是迄今已知的。本節(jié)研究它。</p><p> 覆蓋在各自的時間間隔4σ類
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