KHOA HOC CONG NGHE BAIVI SAT DIEIVI COiXIG SUAT CIJC OAI DAIM PIIM IVAIXIG LUQIVG IVIAT TROI DIJA TREIV DIEU KHIEIV IVID CAU TRUC THAY DOI , ; ; , Nguyfen Vilt Ngu^''''^ Wang Hong Hua\ Lfe Thi Minh Tam^[.]
KHOA HOC CONG NGHE BAIVI S A T DIEIVI COiXIG S U A T CIJC OAI DAIM PIIM IVAIXIG LUQIVG IVIAT TROI DIJA TREIV DIEU KHIEIV IVID CAU TRUC T H A Y DOI , ; ; -., Nguyfen Vilt Ngu^'^ Wang Hong Hua\ Lfe Thi Minh Tam^ TOMTAT Bai bao trinh bay phuang phap MPPT (Maximum Power Point Tracking) dan pin nang lugng mat troi dua trfen dieu khien ma cau tnic thay ddi Phuang phap dieu khien khien cho he thdng luon lam vifec dn dinh d diem cong suit cue dai Hon niia, no co kha nang bam sat tdc nhanh va chinh xae dieu kifen moi tru'ong bfen ngoai thay ddi Kfei qua thuc nghiem dieu kien thai tifei troi ram va co nang cho thay dan pin nang lugng mat troi vin luon lam viec MPPT (P„, = 55 W) Xu the bien ddi cong suit P ddng nhat voi xu the bie'n doi cuang anh sang S, ma difen ap U vin dam bao a lan can diem cong suit cue dai (MPPT) Tu khoa.- Pin nang lugng mat trdi, dieu khien ma, bam sat diem cong suat cue dai (MPPT), mdi trudng ben ngoai LMffDAU Dan pm nang lugng mat trdi ed dac dilra la khong nhilm, khong ed tiing dn, la mpt loai ngudn nang lupng sach dugc su dung rit phd biin frong tuong lai Nhung dan pin nang lupng mat trdi ed dae tinh phi tuyin tinh ro ret D l thue hifen tdi uu hda edng suit dau ciia din pin nang lupng mat trdi thi ein phai tiln hanh thuc hifen bam sat diera cong suit cue dai (MPPT) diu dan pin nang lupng mat trdi Mach difen dilu khiln MPPT thudng sii dung phuang phap ed dinh difen ap, phuong phip quan sat dao ddng, phuang phap tang lupng difen din va phuang phap dilu khien md' '^' ^' Nghifen ciiu dua vao dae tinh eua dan pin nang lugng mat trdi, phan tieh va dua phuong phap dilu khien MPPT dan pin nang lupng mat trdi thich hpp Trfen ea sd' su dung dilu khiln md' d l dilu khiln MPPT, dua mdt loai phuong phap dieu khiln rad' eau tnic thay ddi va da tife'n hanh nghifen ciiu thue nghiera Kit qua thuc nghiera cd trang thai tinh va dpng rat tdt II niOl DUniG VA PHUONG PHAP NGHIEN CUU Dac tinh cua dan pin nang luong mat frdi Pin nang lupng mat trdi (hay pin quang difen), la thilt bi ban din ehiia lupng ldn cic diod p-n, ed kha nang chuyen ddi nang lupng anh sing mat frdi thinh nang lupng difen Dac tinh ea ban ciia pin nang lupng ' Dai lioc Ha Hai, Nam Kinh, Trung Qu6c •Dai hoc Su pham Ky thuat Hung Yen, Viet Nam mat trdi gin gidng vdi diod p-n Mach difen tuong duong eiia nd dugc t h i hifen b hinh R \AA Phu tai Hinh Mach difen tuong duong cua dan pin nang lugng mat frdi Tu sa mach difen tuong duong eua din pin nang lupng raat trdi ta cd quan he ddng difen, difen ap vdi eong suit diu eua dan pin nang lupng mat trdi dugc bilu thi bang eac eong thiic sau'^': / = /,„-/„-/,, I, = / 1000 '/,/, ''qjU + IlC -1 exp nlcT,j + c , (r - 7-,^^) (2) Trong dd: I la ddng difen diu dan pin nang lugng mat trdi, (A); I,,,, la ddng difen anh sang raat frdi va pin nang lupng mat trdi tao ra, (A); ID la ddng difen ehay qua diod D, (A); I^i, la ddng difen ehay qua ndi tra R^n eiia dan pin nang lugng mat trdi, (A); IQ la ddng difen bao hda, don vi (A); I^c la ddng dien ngan raach eiia dan Pin nang lupng raat frdi, (A); R^h Rs l i ndi tra song song va npi tra ndi tilp cila dan pin nang lugng mat trdi,, (Q); U la dien ap trfen hai dau ctta phu tai, (V); q la dien tieh, (C); n la he sd mat ghep p-n NONG NGHIEP VA PHAT TRIEN NONG THON - KY - THANG 11/2010 39 KHOA HOC CONG NGHE dan pin nang lugng raat trdi; k la he sd Boltzraan, 0/K); Ttd li nhiet dp tuyet ddi, (K); S,ef la eudng dp anh sang raat trdi ehuan, (W/m^), (lay S,ef = 1000 W/m^; S la cudng dp anh sang mat trdi thue tl, (W/ra^); T,ef la nhifet raoi trudng ehuan, don vi (°C), Oay T,.ef = 30°C); T la nhiet dp moi trudng thue tl, CQ; Cx li he sd nhiet dp; thdng thudng R,h cd gia tri rat ldn va Rs ed gii tri rit nhd vi vay ta ed thi bd qua lirfmg^+^^ , tir dd bilu thiie (1) duae nit gpn lai la: m qU I = I„ -',.^ expK"'^T,jj - •I,U _qU_ exp (4) Z^- Tu eong thiie (2) va (4) cho thay P la ham sd cila eudng dp anh sing S va nhifet dp moi trudng T Day la mdt ham sd phi tuyin tinh, tdn tai rapt gia tri cue dai nhit dl eho tiing trudng hpp eu thi Hinh mo ta dudng cong dae tinh P - U dl cho hai trudng hpp khae Hinh 2a la hp dudng eong dae tinh P - U eho cae gia tri S khae T khong ddi va T,.ef = 30°C Cdn hinh 2b la hp dudng cong dae tinh P H eho cac gia tri T khae S khong ddi va S,.ef =1000W/ra2 Tu hinh 2(a) eho thay, eudng dp inh sang mat trdi thay ddi, nhiet dp moi trudng khdng ddi, eong suit diu dan pin nang lugng mat frdi thay ddi ti lfe thuan vdi eudng dp anh sing mat trdi Tii hinh 2(b) eho thay, nhifet dp moi trudng thay ddi, eudng dp anh sang mat trdi khong ddi, cdng suit diu dan pin nang lugng mat frdi thay ddi ti lfe nghich vdi nhiet dp moi trudng Nhu vay, eudng dp inh sing mat frdi va nhiet dp moi trudng la hai tham sd quan trpng anh hudng true tilp din cong suit diu dan pin nang lugng mat trdi Ro rang dac tinh P - U luon cd diim cue dai Vi vay phai bao dam din pin nang lupng mat trdi ludn lam viee MPPT Phuong phap MPPT thudng diing la: phuong phap cd dinh dien ap; phuong phap quan sat dao dpng; phuang phap tang lupng difen din Phuang phap ed dinh difen ap cd uu dilra la don gian, nhung diim cdng suit lara vile each xa diem edng suit cue dai, hao tdn cdng suit ldn Hien nay, phuong phap quan sat dao ddng va phuong phip tang lupng dien din la hai phuong phap duge ling dung nhieu, hieu suat eao, nhung lupng dilu chinh chu ki ddng cit Ad eua thilt bi ddng cit mach dien MPPT lai la gia tri dat: dat Ad 40 lon, tdc dp MPPT nhanh, thai gian MPPT ngan, nhung dao dpng cong suit d' lan can diim edng suit cue dai ldn, hao tdn eong suit diu ldn; dat Ad nhd, tdc dp MPPT eham, thai gian MPPT dai, dao ddng eong suit a lan can dilra eong suit cue dai nhd, sai lech eong suit diu ldn''" Dua tren dae tinh diu cila dan pin nang lupng mat trdi cd thi tim su khae a hai ben diim eong suit cue dai cua dudng eong dac tinh P-U Ma ham sd phu thude va quy tie dilu khiln eiia dilu khiln ma truyen thdng chua khao sat din dac dilra ciia dan pin nang lugng raat trdi Do dd, b lan can diim cong suit cue dai vin tdn tai sdng dao ddng edng suit nhat dinh /—.t\ /, // / / / // / //y / / \\ ^ y ^ \vi ' X \li| J^^^^ -^-M S- 10 15 ?D 35 Hinh Dudng eong dac tinh P-U cho hai trudng hgp khae Trfen ca sd' nhirng van dl tdn tai eua phuang phap dilu khien ma truyin thdng eung vdi dae diim eiia dan pin nang lugng mat trdi, nghifen ciiu da dua phuang phap MPPT dua trfen dilu khiln md cau tnic thay ddi O radi rapt khu vuc dudng eong dae tinh khae sii dung rapt quy tic dilu khiln md va ham sd phu thude khic nhau, lam cho he thdng phan iing tde dp nhanh dilu kien radi trudng bfen ngoai thay ddi Phuang phip niy khiln cho dan Pin nang lupng raat trdi ludn phat cong suit cue dai, cung liic eung cd tae dung Ioai tni duge hifen tupng dao dpng cdng suit diu din pin nang lupng mat trdi d' lan can dilra edng suit cue dai Nguyfen ly, thilt kl bp dilu khien ma cau tnic thay doi Tii bieu thiie (4) suy vi phan cua edng suit diu ddi vdi difen ip diu ra: dP_= -^w,-^exp qU \ + 3M •h nkT„, nkT Id J dU (5) Tu bilu thiic (5) cho thay dP/dU la ham sd don difeu cua U, U = thi dP/dU la gia fri lon nhat, gin bang gia tn ddng dien ngin mach eiia pin nang NONG NGHIEP VA PHAT TRIEN NONG THON - KY - THANG 11/2010 KHOA HOC CONG NGHE lugng mat trdi; U tang len thi dP/dU giam xudng tii tii, a lan can diera cong suit cue dai dP/dU giim xudng rat nhanh, d' diim cong suit cue dai dP/dU bing khong; U tiep tire tang Ifen, dP/dU chuyin gia tri ara, gia fri tuyet ddi dP/dU tang Ifen nhanh, ldn hon gia tri diim eong suit cue dai d ben trai eiia dudng eong, dudng cong dae tinh dugc bilu thi trfen hinh (¥l s " ^ ^ k l k -.4 -e I -:, '•: iFi ,, •- 1 O 1— I-J ^"" = l_l 0, cdn nlu difen ap ldn hon difen ap dilra eong suit cue dai thi dP/dU < Khi difen ap hai ben dilra cong suit cue dai thay ddi ed thi Idiiln cho eong suit diu ciing thay ddi, tii dd tao sai lech edng suit diu Dua trfen gia tri dP/dU U thay ddi ed thi dilu khiln dl dan pin nang lugng mat trdi bara dilra cong suit cue dai Tuy nhifen dl dim bao bam nhanh cong suit cue dai va giam dao ddng cong suit dat dugc diem cong suit cue dai thi d' radi mgt khu vuc trfen dudng eong dac tinh phii chgn dugc phuong phap dilu khien thich hgp dl thu dugc Ad ein thilt Dl dat dugc y tudng da thilt kl bg dilu khiln cd ciu tnic thay ddi Dudng cong dac tinh dP/dU din pin nang lugng mat trdi phan lim ba khu vue bing hai diem phan each kj > va kg < (xem hinh 3) Khu vuc dP/dU > kl, khu vuc ka < dP/dU < kj va khu vue dP/dU < K2 O eae khu vue khae se lua chgn eae phuong phap dilu khiln ma cd kit cau kbac nhau, eac quy tac dilu khien va ham sd phu thuge ciing khae dl tao dugc Ad thich hgp tii dd se loai tni duge hifen tupng dao dpng cong suit: k2< dP/dU