Available online at ScienceDirect. Procedia Technology 17 (2014 )

Transcription

1 Available online at ScienceDirect Procedia echnology 17 (2014 ) Conference on Electronic, elecommunication and Comuter CEC 2013 Effect of Shading on Serie Solar Module: Simulation and Exerimental eult L. Fialho a,c,. Melicio a,c, *,.M.F. Mende a,b, J. Figueiredo a,c, M. Collare-Pereira a a Univeridade de Évora, Deartment of Phyic, Évora, Portugal b ntituto Suerior de Engenharia de Liboa, Deartment of Electrical Engineering and Automation, Libon, Portugal c DMEC/LAEA, ntituto Suerior écnico, Univeridade de Liboa, Libon, Portugal Abtract hi aer i on the five-arameter modeling for hotovoltaic ytem. Normally, the technical information for hotovoltaic anel i too retricted to identify the five arameter. So, an undemanding heuritic method i adoted in thi aer, requiring only information on oen circuit, maximum ower oint and hort circuit condition. he - and the P- curve for a erie connected monocrytalline hotovoltaic ytem i obtained from the arameter identification uing the heuritic method and validated by comarion with exerimental curve. Alo, a imulation for artial hading on the hotovoltaic ytem i reented to illutrate a feaible aement during the deign of a P ytem for lo of energy converion due to hading he Author. Publihed by Elevier Ltd. hi i an oen acce article under the CC BY-NC-ND licene (htt://creativecommon.org/licene/by-nc-nd/3.0/). Selection and eer-review under reonibility of SEL ntituto Suerior de Engenharia de Liboa. Peer-review under reonibility of SEL ntituto Suerior de Engenharia de Liboa, Libon, POUGAL. Keyword: P ytem; effect of hading; algorithm for arameter etimation; imulation; exerimental reult 1. ntroduction he demand for energy, the hortage of foil fuel and the need for carbon footrint reduction have reulted in a global awarene of the imortance of energy aving and energy efficiency [1] and rogram on the Demand-ide Management have been develoed in order to ait conumer on energy uage. Alo, renewable energy ource coming from wind and olar energy ource are attractive to go into exloitation, conidering not only large cale ytem, but alo micro and mini cale converion ytem, i.e., Diere Generation (DG) owned by conumer. * Correonding author. el.: ; fax: addre: ruimelicio@uevora.t he Author. Publihed by Elevier Ltd. hi i an oen acce article under the CC BY-NC-ND licene (htt://creativecommon.org/licene/by-nc-nd/3.0/). Peer-review under reonibility of SEL ntituto Suerior de Engenharia de Liboa, Libon, POUGAL. doi: /j.rotcy

2 296 L. Fialho et al. / Procedia echnology 17 ( 2014 ) Among the DG the olar generator uually known by the name of hotovoltaic (P) ytem i in nowaday in a number of ower ytem and enviaged a a financially viable romiing indutrial energy converion. A P ytem directly convert olar energy into electric energy. he main device for the energy converion of a P ytem i a olar cell. Cell are groued to form module, module to form anel and anel to form array. A P ytem may be either an array with one anel or a et of anel connected in erie or arallel to form large a P ytem without or with a tracking un ytem. Although cotly, the tracking ytem allow a more roitiou intantaneou orientation for the anel in order to achieve higher value of energy caturing during unny day due to the divere erendicular oition to collect the un irradiation. he erformance of the P ytem deend on the oerating condition eecially on olar irradiation, temerature, configuration and hading. he hading on P anel, for intance, due to a aing cloud or neighboring building caue not only energy lo in the converion, but alo further non-linearity on the - characteritic [2]. A haded anel of a non-uniform illuminated P ytem can be ubmitted to a negative voltage. f there i no rotection, cell breakdown can haen during non-uniform illumination. Hence, normally in order to rotect the cell an extra n-junction i imlemented a a bya diode. For intance, one bya diode connected in arallel with each et of 18 cell [3] or with a anel i common ractice a a comromie between rotection and increae on the cot due to the extra n-junction. Alo hading attern with haty change i not eay for the tracking of the maximum ower oint (P), becaue with non-uniform illumination uually there will be multile local P and they will change a fat a doe the illumination. Under hadowing condition a P array layout can have large energy loe and even mall hadow can noticeably affect the energy yield [4]. n order to better undertand thee iue, for examle from artial hading, and imrove P tracking, model that reolve thi roblem at the level of individual cell are required. Nomenclature D 2 bya diode G olar irradiance 0 diode revere bia aturation current D current at diode D 1 maximum ower oint current leakage current hoto generated electric current c hort-circuit current k Boltzman contant m ideality factor q electron charge equivalent hunt reitance equivalent erie reitance cell -n junction temerature in [K] maximum ower oint voltage oc oen-circuit voltage thermal voltage of the olar cell α c current temerature coefficient voltage temerature coefficient β oc 2. Modelling here are very elaborate model done for a olar cell [5], but in thi aer in order to tudy the effect of hading on P ytem, the equivalent circuit with five arameter wa the followed otion. hi equivalent circuit conit on a current controlled generator, a ingle-diode, a hunt and erie reitance. hi otion i choen not only

3 L. Fialho et al. / Procedia echnology 17 ( 2014 ) becaue of the imlicity of the modeling, but alo in conideration to the tate of the art on the formalit ued for the identification of the arameter. he five arameter equivalent circuit and the bya diode rotection are hown in Fig. 1. G, S D + D 1 D 2 - Fig. 1. Equivalent circuit. he - characteritic aociated with the equivalent circuit five arameter modelling hown in Fig. 1 i an imlicit function given by: m ( e 1) (1) 0 where i the n-junction thermal voltage given by: k (2) q Equation (1) ha to be olved uing a numeric iterative method, for intance the Newton-ahon method. From (1), conidering hort-circuit condition, i given by: c c m 0 ( e 1) (3) he econd term of (3) i uually mall in comarion with the firt term [6,7], becaue the diode revere bia aturation current, 0, i a value in the range of a few micro Amere and the erie reitance,, i a mall value. So, the uually aroximation by defect conidered for i given by: c (4) he diode revere bia aturation current, 0, conidering oen circuit condition in (1) i given by: oc (5) 0 e oc m 1

4 298 L. Fialho et al. / Procedia echnology 17 ( 2014 ) Subtituting (4) into (5) and conidering that the exonential term i ignificantly greater than one unit, 0 i aroximated given by: oc m c( ) oc 0 e (6) he derivative of the current in (1) in order to the outut voltage at P i given by: m 0e ( m 1 ) (7) Attending that at P the derivative of the electric ower in order to the voltage ha a null value, the derivative in (7) i alo equal to the ymmetric of the quotient between the maximum ower oint current,, and the maximum ower oint voltage,. So, by equating the two derivative, the i comuted by the imlicit exreion given by: ( m 0e )( m 1 ) (8) Auming (8) [7], the equivalent hunt reitance i aroximated by a function of the ideality factor m and of equivalent erie reitance, given by: ( ) m ( )( ) m c (9) and from (6) of [7] i aroximated by a function of m and of, given by: 1 ( ) m c oc { oc m ln [ ]} (10) m ( ) 2 he ideality factor can be evaluated uing (1) at P, relacing S given by (4), 0 given by (6) and taking logarithm [7]. Hence m i aroximated by a function of and of, given by: c oc m (11) c( ) oc ln [ ] ( )( ) c he ytem with the imlicit exreion (9), (10) and (11) allow to comute the unknown m, and. Becaue > 0, (10) imoe the following imlicit relation given by: oc m (12) m c( ) oc ln m ( ) 2 c

5 L. Fialho et al. / Procedia echnology 17 ( 2014 ) and to aure that <, then the denominator in (9) mut be greater than zero [7]: ( )( c ) m (13) A weighting factor le than one hould be conidered in the right ide of (13) to et u an equality in order to find an aroximation for m. So, a lauible aumtion to et u the equality in order to comute m [7] i given by: / c (14) he above et of exreion (4), (6), (9), (10) and (11) are ued to determine a a heuritic method to find an aroximation for the value of the five arameter of the equivalent circuit, uing only data from oen circuit, maximum ower oint and hort circuit condition. With thee five arameter, equation (1) i olved uing Newton-ahon method in order to obtain the - value. hi heuritic method wa uccefully ubjected to exerimental and imulation tet. 3. Cae Study he heuritic method modelling for the olar cell equivalent circuit with ingle-diode, hunt and erie reitance wa imlemented in Matlab/Simulink. he imulation reult reorted are carried out for a monocrytalline P module technology with two module connected in erie. he exerimental data meaured are rovided in [8], obtained in a hotovoltaic facility located at N, W, at Laboratório Nacional de Energia e Geologia (LNEG) in Libon, Portugal. he - curve were extraolated to SC, according with the uual method [9,10]. he tracer ued howing the - curve i hown in Fig. 2. Fig. 2. he - curve tracer. able 1 ummarize the data for the ilicon monocrytalline olar module Siemen SP75 at SC [11].

6 300 L. Fialho et al. / Procedia echnology 17 ( 2014 ) able 1. Data for the Siemen SP75 olar module at SC echnology * m * m * oc * c Cell α c β oc Monocrytalline A A ma/ºc -77 m/ºc he P ytem teted formed by two monocrytalline olar module connected in erie [8] without tracking of the un are imlemented a hown in Fig. 3. Fig. 3. P ytem formed by two monocrytalline olar module connected in erie [8]. he artial hading imulation wa carried with the two P module aociated in erie having the rotection diode a hown in Fig. 4. G 1 1 P module 1 G 2 2 P module 2 Fig. 4. Partial hading configuration.

7 L. Fialho et al. / Procedia echnology 17 ( 2014 ) he artial hading i given by the following etting: G 1 = 1000 W/m 2 and G 2 = 700 W/m 2. he circuit equivalent of both module i a hown in Fig. 1, becaue every cell of a module i aumed to be ubjected to the ame olar irradiance, i.e., uniform illumination i aumed over each module, but with different value. he - curve imulated and exerimental without hading and imulated with hading are reectively hown in Fig. 5. Fig. 5. Simulated and the exerimental - curve without hading and imulated with hading. he P- curve imulated and exerimental without hading and imulated with hading are reectively hown in Fig. 6. Fig. 6. Simulated and the exerimental P- curve without hading and imulated with hading.

8 302 L. Fialho et al. / Procedia echnology 17 ( 2014 ) Fig. 5 and Fig. 6 reveal the imlication in the - and P- curve due to the hading, i.e., due to the non-uniform illumination on the two erie module there are two local P, which can oe a difficulty to the P tracking ytem and there i lo on the exected energy converion. 4. Concluion he five-arameter olar cell equivalent circuit i alied in order to acquire - and P- curve. he five arameter are etimated by a heuritic method uing a et of exreion requiring only the normal given information by the roducer of P module about oen circuit, maximum ower and hort circuit data. Once the identification of arameter i done, a imulation of the hading effect i oible. he imulation can how the effect of artial hading in reducing the energy obtained by a olar P ytem, which hould be taken in conideration during the economic evolution in the deign hae. Comarion between imulated and the exerimental reult how that the heuritic method i a atifactory one. A cae tudy with a hading effect imulation i reented to how the conequence in what concern caturing of maximum energy, i.e., P tracking. Acknowledgement hi work wa artially uorted by Fundação Ciência e ecnologia, through DMEC under LAEA and by Univeridade de Évora, Cátedra BES Energia enovávei. he author gratefully acknowledge to M. L. Giacobbe for roviding the meaured data of amorhou P module at LNEG. eference [1] Seixa M, Melício, Mende MF. A imulation for accetance of two-level converter in wind energy ytem. n: Proc. 3.a Jornada de nformática da Univeridade de Évora JUE2013. Évora, Portugal; [2] Patel H, Agarwal. MALAB-baed modelling to tudy the effect of artial hading on P array characteritic. EEE ranaction Energy Converion 2008;23: [3] Quachning, Hanitch. Numerical imulation of hotovoltaic generator with haded cell. n: Proc. 30th Univeritie Power Engineering Conference. London, UK; [4] Woyte A, Nij J, Belman. Partial hadowing of hotovoltaic array with different ytem configuration: literature review and field tet reult. Solar Energy 2003;74: [5] Catañer L, Silvetre S. Modeling of hotovoltaic cell uing free oftware alication for training and deign circuit in hotovoltaic olar energy. John Wiley and on LD; [6] Carrero C, odríguez J, amírez D, Platero C. Simle etimation of P module lo reitance for low error modelling. enewable Energy 2010;35: [7] Carrero C, odríguez J, amírez D, Platero C. Accurate and fat convergence method for arameter etimation of P generator baed on three main oint of the curve. enewable Energy 2011;36: [8] Giacobbe L. alidação de modelo matemático de comonente de itema fotovoltaico. Mater hei (in Portuguee). Libon: Deartamento Engenharia Eletrotécnica Comutadore/ntituto Suerior écnico; [9] EC Procedure for temerature and irradiance correction to meaured - characteritic. 2nd ed. Geneva: EC; [10] EC Photovoltaic device - Part 1: Meaurement of hotovoltaic (P) current-voltage characteritic.. 2nd ed. Geneva: EC; [11]Siemen Photovoltaic Product nformation, htt://