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NG DNG MATLAB/SIMULINK XY DNG M HNH V M PHNG H THNG NI LI S DNG NGUN PIN MT TRI

KT HP NGUN C QUYL Kim Anh *

Tm tt

Bi bo gii thiu ng dng Matlab/Simulink xy dng m hnh v m phng h thng ni li s dng ngun pin mt tri kt hp ngun c quy. Nh chng ta bit, ngun nng lng mt tri l ngun nng lng sch c tr lng ln, ang l mc tiu nghin cu ca nhiu nc trn th gii nhm thay th dn ngun nng lng ha thch c nguy c cn kit, gy nhim mi trng. Trong qu trnh lm vic, pin mt tri ph thuc nhiu yu t nh hng nh cng nh sng, nhit mi trng, hin tng bng rm mt khc, cng sut sinh ra do tm pin mt tri ph thuc vo bc x mt tri v nhit . Nhm nng cao hiu sut s dng ca pin mt tri kt hp ngun c quy v thc hin ni li, i hi phi c cc gii thut iu khin. y s dng gii thut h bm im cng sut cc i nhm m bo rng pin mt tri s lun lun lm vic im cc i khi ti thay i.

T kha: Nng lng ti to, pin mt tri, mt tri ni li, ngun c quy, h bm im cng sut cc i.

Abstract

The article aims to introduce the application of Matlab/Simulink in modelling and simulation of combined solar cells and batteries power sources connected to power grids. As we know, solar power, a clean energy source which has large reserves, is a target for the study of many countries in order to gradually replace fossil energy sources both at risk of depletion and causing environmental pollution. The working process of solar cells depends on many factors such as light intensity, environment temperature, the phenomenon of shade ... furthermore, power generated by solar panels is dependent on the solar radiation and heat. In order to improve the efficiency of combined solar cells and batteries and grid-connected implementation, the control algorithms ared required. Here using the algorithm of maximum point power tracking ensures that solar cells will always work at peak although the load changes.

Keywords: Renewable energy, solar cells, grid connected solar cells, battery power, maximum point power tracking.

* Trng Cao ng Cng Nghip Tuy Ha

1. t vn

Ngun in mt tri l dng ngun nng lng ti to v tn vi tr lng ln. y l mt trong cc ngun nng lng ti to quan trng nht. Vic tm cc cch thc khai thc, s dng ngun nng lng in mt tri ny sao cho hiu qu v thay th dn cc ngun nng lng ha thch ngy cng cn kit, gy nhim mi trng ang l mc tiu nghin cu ca nhiu quc gia. Nng lng mt tri (NLMT) thc cht l ngun nng lng nhit hch v tn ca thin nhin. Hng nm, mt tri cung cp cho tri t mt nng lng khng l, gp 10 ln tr lng cc ngun nhin liu c trn tri t. Hin nay, nc ta ch yu s dng h thng pin mt tri c lp, hoc h thng c lp kt hp gia pin mt tri v cc ngun nng lng khc nh ngun c quy, pin nhin liu..vv. Bi bo ng dng matlab/simulink xy dng m hnh v m phng

h thng ni li s dng ngun pin mt tri kt hp ngun c quy iu khin theo phng php bm im cng sut cc i (MPPT). K thut iu khin tm kim da trn m hnh nhm hng n pht trin li in thng minh v iu khin ni li linh hot cho cc ngun nng lng ti to.Bng 1. Mt NLMT trung bnh nm v s gi nng theo khu vc (Ngun: VNL)

Khu vcNLMT trung

bnh nm(kcal/cm2)

S gi nng trung bnh

nm(hrs/nm)

1 ng Bc B 100 - 125 1500 - 1700

2 Ty Bc B 125 - 150 1750 - 1900

3 Bc Trung B 140 - 160 1700 - 2000

4 Nam Trung B v Ty Nguyn 150 - 175 2000 - 2600

5 Nam B 130 - 150 2200 - 2500

Trung bnh c nc 130 - 152 1830 - 2450

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Bng 2. in t NLTT cng sut lp t giai on 2011 2030 (ngun: Quyt nh s 1208/Q TTg ngy 21/7/2011 ca Th tng Chnh ph, Ph lc 1)

Nm Cng sut lp t(MW) NmCng sut

lp t(MW)

1 2011 30 8 2018 200

2 2012 100 9 2019 230

3 2013 130 10 2020 300

4 2014 120 11 2011 - 2020 1.660

5 2015 150 12 2021 - 2025 2.500

6 2016 200 13 2026 - 2030 4.200

7 2017 200 2011 - 2030 8.360 = 8.36GW

2. M hnh iu khin ni li s dng ngun pin mt tri kt hp ngun c quy

H thng ni li s dng ngun pin mt tri kt hp ngun c quy bao gm cc thnh phn c bn nh Hnh 1.

Hnh 1. S cu trc c bn iu khin ni li ngun pin mt tri kt hp ngun c quy

2.1. M hnh ngun pin mt tri (PV)

* Pin mt tri PV (Photovoltaic cell) gm cc lp bn dn chu tc dng ca quang hc bin i cc nng lng phton bc x mt tri thnh nng lng in. Theo quan im nng lng in t, pin mt tri c th c coi l nhng ngun dng biu din mi quan h phi tuyn I-V nh Hnh 2.

Hiu sut ca tm pin mt tri s ln nht khi pin mt tri cung cp cho ta cng sut cc i. Theo c tnh phi tuyn trn hnh 2, n s xy ra khi P-V l cc i, tc l P-V = Pmax ti thi im (Imax,Vmax) c gi l im cc i MPP (Maximum Point Power). H bm im cng sut cc i MPPT (Maximum Point Power Tracking) c s dng m bo rng pin mt tri s lun lun lm vic im MPP bt chp ti c ni vo pin.

* Dng in u ra ca pin theo [Saurav Satpathy, Aryuanto Soetedjo] c tnh nh sau:

Trong : q: in tch electron = 1.6 x10-19 C, K: hng s Boltzmanns = 1.38 x10-23J/K, Is: l dng in bo ha ca pin, Iph: l dng quang in ,Tc: nhit lm vic ca pin, Rsh : in tr shunt, Rs : in tr ca pin, A: h s l tng.

Theo cng thc (1), dng quang in ph thuc vo nng lng mt tri v nhit lm vic ca pin do :

Hnh 2. c tnh lm vic ca pin mt tri

Hnh 3. S tng ng ca pin mt tri (2)

(1)

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Vi: Isc: l dng ngn mch nhit 250C,

KI: h s nhit ca dng in ngn mch, Tref: nhit ca b mt pin (nhit tham chiu), H: bc x ca mt tri kW/m2.

y, gi tr dng in bo ha ca pin vi nhit ca pin c tnh nh sau:

Trong : IRS: l dng bo ha ngc b mt nhit v bc x ca mt tri, EG: nng lng vng cp ca cht bn dn, ph thuc vo h s l trng v cng ngh lm pin.

Mt khc, mt pin mt tri c in p khong 0,6V. Do mun c in p lm vic cao th ta mc ni tip cc pin li, mun c dng in ln th mc song song. Nh vy, dng in mt modul tm pin s l:

2.2. M hnh ngun c quy

Theo [M.Makhlouf, F.Messai , H.Benalla], in p ca c quy v trng thi np (state of charge SOC) c xc nh theo biu thc:

Trong : v1: in p thay i ca c quy (V); Ib: dng in (A); Qm: dung lng ln nht ca c quy (Wh); kb: h s np v x ; D: t l x.

T biu thc (5), gi tr in p thay i ca c quy c tnh nh sau: v1=[2+0.148.SOC(t).ns] (6)

Vi ns: s lng c quy 2V ni tip.in tr ca c quy l:

2.3. Phng php iu khin

iu khin ni li ngun pin mt tri kt hp ngun c quy, ta s dng phng php iu khin bm im cng sut cc i (MPPT). Hin nay, k thut iu khin bm im cng sut cc i c th phn thnh 2 nhm chnh sau: nhm k thut tm kim v nhm k thut tm kim da trn m hnh. K thut tm kim d thc hin nhng i hi mt s bc ln mi hi t c im cc i (MPP), cn nhm k thut tm kim da theo m hnh s hi t rt nhanh im MPP. Tuy nhin, vic s dng k thut tm kim da theo m hnh th i hi ta phi bit chnh xc thng s ca pin mt tri v cc s o, k c nhit v bc x mt tri.

3. Cc b bin i

Theo [D. Ganesh, S. Moorthi, H. Sudheer], thc hin chuyn i 2 trng thi ta s dng b chuyn i DC/DC (t ngun mt chiu thnh ngun xoay chiu) nhm thch nghi vi mc in p v in tr t tm pin mt tri. Ngoi ra cn b nghch lu DC/AC bin i (t ngun mt chiu thnh ngun xoay chiu) thc hin ni ti v ni li xoay chiu (AC).

(3)

Hnh 4. Dng in 1 modul tm pin

Hnh 5. S cc b chuyn i DC/DC; DC/AC

(5)

(7)

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4. Xy dng m hnh v m phng trn Matlab/Simulink 4.1. Xy dng m hnh trn Matlab/Simulink

Hnh 6. M hnh Pin mt tri Hnh 7. B chuyn i 2 trng thi DC/DC

Hnh 8. M hnh iu khin ni li s dng ngun pin mt tri kt hp ngun c quy

4.2. Kt qu m phng trn Matlab/Simulink

Hnh 9. c tnh I - V Hnh 10. c tnh P - VNhn xt: kt qu m phng cho thy khi chiu (G) thay i th dng PV thay i mnh, p PV t thay i v cng sut ca PV ph thuc nh hng ca chiu .

Hnh 11. in p u ra U_dc(V) Hnh 12. Cng sut u ra P (W)

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Hnh 13. in p u ra Uabc (V) Hnh 14. Dng in u ra Iabc (A)

Hnh 15. in p ni vi li Uabc (V) Hnh 16. Dng in ni li Iabc (A)

5. Kt lun

M hnh iu khin ni li s dng ngun pin mt tri kt hp ngun c quy s dng gii thut iu khin bm im cng sut cc i (MPPT), cng sut ca PV thu c lun t gi tr cc i, ng vi cc chiu sng khc nhau. Ti thi im t = 0.2s, dng v in p u ra t gi tr n nh v bng gi tr t, ni li thng qua my

bin p v ng dy ti in. Hin nay, nc ta ch yu s dng h thng nng lng mt tri c lp nn cn nhiu hn ch v bt cp. Do vy, h thng iu khin ni li s dng ngun pin mt tri kt hp ngun c quy l mt gii php nhm hng n pht trin li in thng minh v iu khin ni li linh hot cho cc ngun nng lng ti to.

Ti liu tham kho

Aryuanto Soetedjo, Abraham Lomi, Yusuf Ismail Nakhoda, Awan Uji Krismanto. 2012. Modeling of Maximum Power Point Tracking Controller for Solar Power System. Telkomnika.

D. Ganesh, S. Moorthi, H. Sudheer. 2012. A Voltage Controller in Photo Voltaic System with Battery Storage for Stand Alone Applications. International Journal of Power Electronics and Drive System.

ng nh Thng. 2012. Cng ngh Pin mt tri bi hc kinh nghim t Vit Nam. Trung tm nghin cu nng lng mi. Trng i hc bch khoa H Ni.

Hong Dng Hng. 2008. Nng lng mt tri l thuyt v ng dng. Trng i hc Bch Khoa Nng.

M.Makhlouf, F.Messai , H.Benalla. 2012. Modeling and Simulation of Grid-connected Hybrid Photovoltaic/Battery Distributed Generation System. Canadian Journal on Electrical and Electronics Engineering Vol. 3, No. 1, January.

Saurav Satpathy. 2012. Photovoltaic power control using MPPT ang boost converter. Department of Electrical Engineering National Institute of Technology. Rourkela.