Ngo Ehic Minh Tap chi KHOA HOC & CONG NGHE 122(08): 3-8
PHAN TICH t u ' d i ©IEN KIN VA I T N G DUNG C O N G N G H E F A C T S CHO DIEU K H I £ : N D 6 N G C O N G SUAT
Ng6 Dire Minh Truang Dai hoc Ky thugt Cong nghiep - DH Thdi Nguyen TOM TAT
No luc Clia bfii bfio la phoi hgp giua phuong phfip phan tich ludi dien tmyen thong vdi md phong bang Matlab de trinh bay nh&ng hoat hoat dgng co ban ciia he thong dien thong qua mot md hinh nghien cim tdi gian nhung vln dam bao tinh tdng quat, trong do co iing dung cong nghe FACTS Noi dung chinh g6m: Xfiy dung mpt md hinh ludi difn kin dien hinh dugc suy ra tir nh&ng so do chufin Clia IEEE de phuc vy chung cho nhieu hudng nghien ciru; Phan tich ludi, danh gifi nh&ng yeu to anh hudng den ddng cong suat trong ludi va xet rieng cho mpt yeu to cu the lfi dien ap niit;
LTng dung cdng nghe FACTS vdi thilt bi STATCOM-PWM bu cong sufit phan khang dl diiu chinh dien fip niit vfi do d6 dilu khiln dong cdng suit trong ludi; Mo hinh md phdng bSng Matiab- Simulink ludi dien kin co STATCOM-PWM vdi cfiu hinh nghich liru Multi-level; Phan tich dfinh gifi cfic kit qua nghien ciiu thu dugc va de xufit cfic nghien cim tiep theo.
Til' khda: Ludi dien kin. DCS. STATCOM-PWM, Dien dp mil. multi-level. FACTS DAT VAN DE
FACTS (Flexible Alternating Current Transmission Systems) dugc dl xufit dau tien vfio nam 1988 d vien EPRl (Electric Power Research Institute) tgi Hoa Ky. Dfiy la khai ni?m ve mpt he thdng dien linh hogt. Cd nghTa la cac thdng sd ciia he thdng dugc dieu khien, dap iing nhanh chdng theo dau vfio cung nhu khi thay ddi diem lfim viec.
Cdng nghe FACTS dua tren co sd cfic bd biln doi VSI (Voltage Source Inverter), VCS (Voltage Source Converter) cdng sufit Idn [1],[2]. Do su phat trien ciia cdng nghe sfin xuat cac thilt bj diln tir cdng suit ldn nhu GTO, IGTO, IGBT,... da cho phep irng dung vfio h? thong di$n nhfim nfing cao khfi nang dilu khien ddng cdng sufit (DCS) cfi ve dp Idn, phuong chieu vfi chfit lupng trong ludi di?n kin. Day lfi thl mgnh chinh giup cho FACTS ra ddi vfi phat trien ben viing. Cho den nay, FACTS dang ngfiy cfing phfit trien d hau hit cfic nudc tren the gidi. Vi the, van de tiep can vfi irng dyng cdng ngh? FACTS la tfit yeu cho giang dgy, nghien ciiu va iing dung trong h? thong di?n Vipt Nam.
FACTS la tgp hgp rat phong phii cua nhilu thiet bj. Tuy nhien, cd the chia ra thfinh cfic
nhdm chinh theo hinh thiic ket ndi: ndi tiep, song song, hdn hgp. Dfic tinh hogt ddng ciia chung dugc suy ra tir hai kieu bii ndi tiep va bii song song ly tudng.
Tel. 0982 286428
Hinh I. Mo hinh ludi dien kin 2 nguon, 5 niit Khi phfin tich mdt ludi dien kin, gifi sir theo mdt md hinh dfi dupc IEEE chufin hda nhu tren hinh 1, cfic thufit toan dupc ap dyng nhfim xac djnh chi ra dd ldn, phucmg chieu ddng cdng suat tren cac tuyen dudng dfiy vfi tdi iru hda bfii toan nay theo mdt tieu chi nfio dd nham dfip iing yeu cfiu cu the trong van hanh he thdng dien [3],[4].
Tuy nhien, neu khdng ke den che do su cd nfing cd the gay tan ra ludi (phgm vi bai bfio nay khdng xet den che dp su cd nang), trong thuc te cac thdng sd van hanh he thdng van cd the vupt ra ngofii pham vi cfic dieu kien dau
Ngo Dlic Minh Tgp chi KHOA HOC & CONG NGHE 122(08); 3-8 cua bfii tofin tdi uu dua trang thai be tbdng xa
rdi che do tdi uu dgt ra.
Nhung thdng sd thudng hi thay ddi do la:
- Tdng trd dudng day bi thay ddi trong trudng hgp ddng hofic cat mpt Id trong cap ddi dudng dfiy song song;
- Thay ddi tfii tai cfic mit;
- Dien ap niit thay ddi do cac thao tac ddng cat trong ludi: ddng cat tai, dudng day, may bien ap, ngudn... hofic do ngan mgch xa.
Cac tac ddng tren deu lam thay ddi DCS tren dudng day, dich chuyen diem phfin bd cdng suat ban dfiu dfin den xuat hien nhung trgng thai bfit thudng Vt du nhu: xufit hien nhung dudng dfiy khdng mang tfii, hofic chi mang tfii mdt thfinh phan P hofic Q, hoac ddi chilu DCS, hofic DCS P va Q ngugc chieu nhau.
Theo each tiep can nfiy, tfic gia de xufit hudng nghien ciiu ciia bai bfio theo 2 ndi dung chinh:
- Phfin tich ludi nhfim tudng minh hda bfin chfit vat ly ciia hoat ddng ludi dien, nhirng tfic ddng lfim thay ddi DCS.
- U'ng dung cdng nghe FACTS dieu chinh ddng cdng sufit trong ludi theo mong mudn.
PHAN TiCH LUCll
Hinh 2, Sa do ca bdn ludi dien kin Nguyen ly chung
Trong ludi dien kin, mgt niit phu tfii bat ky dlu cd kha nang duoc cap dien it nhfit lfi tir hai phia. Thuc chat so dd ludi tren hinh 1 hay nhiing ludi phiic tgp hem deu cd the dugc xem nhu la sy md rdng tir mdt dgng so dd co ban nhu so do tren hinh 2 vdi 03 nut A, B, C ; 05 tuyln dudng dfiy Ll... L5; 02 ngudn cung cap Nl va N2.Bieu thiic tdng quat tinh ddng cdng sufit chay tren cfic dudng day dupc xac dinhtheo(l)va(2).[3]:
N I U tinb tir phia NI:
Hofic tinh rtr phia N2:
! ^ W ^ k z ^ + 5 ^ (2)
Gifi thilt, thdng sd cac dudng day ciia so do ghi trong bang 1,
Bang 1. Thong so duang ddy Thong s6 dudng day
R JX
T6ng no 143 48 4 14.3+48.4i Ll 22 0 13 0 44 2 86 9 68 2 86+9 68i L2 22 0 13 0 44 2 86 9 68 2 86+9 68i L3 22 0 13 0.44 2 86 9 68 2 86+9 68i L4 22 0 13 0 44 2 86 9 68 2,86+9 68i L5 22 0 13 0.44 2 86 9 68 2.S6+9 68i Xet che dd
gidng nhau.
S Sa Sb Sc
dac biet cu the gh
cac phy trong bfin
tai CO gia tri g 2 Bfing 2. Phu ldi Igi cdc nut
Phu tfii P 5 5 5
tai cfic nui Q
1 1 1
S 5+jl 5+jl 5+jl Tru&ng hap thu nhdt: Thdng sd ngudn gidng nhau ca ve do ldn va gdc pha.
Ap dyng (1) vfi (2) tinh dupc cdng suat chay tren cac dogn dudng day va ket qufi thu dupc the hien tren bieu dd hinh 3. Trong dd, chieu DCS da quy udc theo chieu mui ten tren so dd hinh I. Neu cdng sufit am se dugc hieu Ifi ddng cdng sufit thuc tren dudng day do ngupc chieu mui ten.
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Hinh 3. Bieu do dong cong sudt Quan sat hinh 3 thfiy bai dudng dfiy L3 vfi L4 kbdng mang tai. Neu thay ddi thdng so dudng
Ngo Dlic Minh Tgp chi KHOA HOC & CONG NGHE 122(08): 3 - 8 dfiy, DCS tren cac dudng day s6 thay ddi
theo. Vi dy:
Thay ddi giam mpt mia chieu dai ciia L2= 11 km, tuong duong chl do chuyin tir mdt sang vgn hfinh hai dudng day song song. Kit qufi tinh thl hi$n tren bilu dd hinh 4 cho thfiy DCS tren L3 va L4 khfic khdng. DCS dugc tang cudng tir phia ngudn NL
^
S l S2Hinh 4. Gidm L2, DCS tren L3 duang - Tfing gap ddi chieu dai ciia L2=44km, ket qufi tinh thl hien tren bilu dd hinh 5 cho thay DCS tren L3 vfi L4 am (ddi chilu), DCS dugc tang cudng tir phia nguon N2.
0 -
1
5 1
1
S2 53
«.
•
55
• a Hinh 5. DCS tren L3 vd L4 ddi chiiu Tric&ng hgp th^ hai: Thdng sd ngudn khac nhau cfi ve dp ldn va gdc pha.
a) Hai ngudn chimg pha nhung khfic nhau vl dg idn, gifi sii
UNi=108kV, UN2=106kV.
Theo (1), ddng cdng suat tren cfic dudng dfiy tinh dugc the hign tren bilu dd binh 6.
i f e ^
Hinh 6. DCS tren dudng ddy khi UN, >UN2 Trong do, tbanh phan DCS khdng can bang cd the duprc tfich rieng vfi the hi?n tren bilu do hinh 7.
Tir bieu dd hinh 7 cho thfiy DCS tac dyng P chgy til ngudn cd dien fip cao sang phia ngudn cd dien fip thap, cdn ddi vdi DCS phan khfing Q thi nguac lai (ddng chgm sau 90"). Tren dudng day ddng cdng suat P va Q chgy ngugc chieu nhau.
b) Hai ngudn khac nhau cfi ve pha vfi dp ldn, gia sii:
UMi=108Z0.137kV,
U N 3 = 106Z0.194kV.
Ket qua tinh toan thu dupc the hien tren bieu dd hinh 8.
Hinh 8. Dong cong sudt P. Q Nhfin xet: Cfic bieu do tren da lam ro cdng thirc (1) vfi (2). Xet trong trudng hgp nay, DCS tren mdt dogn dudng dfiy phu thupc vao hai yeu td, dd lfi:
- Tdng trd ciia dudng dfiy, - Dp chenh the giua hai dau dudng day.
Trong dd, su khac nhau ve gdc pha thuc chat
!a khac nhau ve tri sd dien fip xet theo thdi gian tuc thdi (dp chenh the). Rd rfing, DCS tac dyng van cd chieu tir phia ngudn N2 cd dien fip 106kV thap ban sang phia ngudn Nl cd dien fip 108kV cao hon vi N2 cd gdc phfit sdm hon. Hay cd the dien dat dieu nfiy theo cfich khac thdng qua md hinh ludi dien kin cd so do nhu tren hinh 9.
Hinh 9. Mo hinh lu&i di?n kin 2 nguon DCS tac dyng P va DCS phfin khfing Q dugc xac dinh theo (3) vfi (4), [4].
v.y.,
(3)
Hinh 7. DCS khdng cdn bdng khi UN, >Um
v,,v.
{cosd (4)Ngd Dlic Minh Tap chi KHOA HOC & CONG N G H E 122(08): 3 - 8 Trong dd, de chi gifi tri dien fip dirng ky hieu
la chii V; hieu gdc pha ciia dien fip ciia hai ngudn Ifi S = 5) - 82.
Nhu vgy, ddng cdng sufit tren dudng day cd the thay ddi thdng qua dieu chinb gia tri dien ap mit hofic thay ddi tdng trd dudng day. Bai bao nfiy lua chgn giai phap dieu chinh dien fip nut bfing thiet bj bii song song la STATCOM- PWM. Bdi le, vdi mdt niit xa ngudn thi viec dieu chinh dien ap thuc hien tir mfiy phfit Ifi bat cap (cdng nghe cu). Mat khac trong mdt ludi phiic tap cd nhieu mit, viec lua chgn vi tri va sd lupng STATCOM ciing lfi mdt bai toan kho ma cfic ky su nang lupng phfii ddi mat. Tuy nhien, trong thuc te ludi dien thudng cd cau triic khdng qufi phiic tgp. Cac nghien ciru ap dyng cho so do tren hinh 2 Ifi hofin toan dam bfio tinh tdng quat.
L/NG DUNG STATCOM-PWM DIEU CHINH DONG CONG SUAT
Lira chon STATCOM
Thay cho cau hinh STATCOM trudc dfiy thudng su dyng cac van bfin dan Thyristor cd dieu khien gdc md cham a nen DCS phan khfing do STATCOM phfit ra cd chat lupng thfip, dp meo dang sin cang Idn khi gdc a cang ldn, vi du nhu tren hinh 10, [5].
~-1—H-
Hinh 10. Dong dien cda STATCOM-FWM Trong nhiing nam gan day, cac STATCOM dfi cd nhieu tien bd ve cfi cau true mgch luc vfi he dieu khien. Trong bfii bao nay, ung dung STATCOM-PWM cd cau hinh cao dugc md tfi tren hinh 11.
Trong dd:
- Cac Bridgel va Bridge2 diing van TGBT lam viec theo nguyen ly PWM,
- He dieu khien dugc fip dung phuang phfip dieu che vec to khdng gian SVM, nghich luu multi-level. [5],[6].[7],[8].
Hinh 11. Cdu triic sa do khoi cda STATCOM-PWM Thiet ke sff do mo phong STATCOM- PWM trong luoi dien kin
Muc tieu 6k ra cho STATCOM-PWM:
- Bil dien fip mit dl dilu chinb DCS tren dudng day;
- On djnh dao dgng cdng suat trong trudng bgp dien fip bi kich dgng tir phia ngudn.
Tu dd, cfiu true md phdng bfing Matlab ciia ludi dien kin tren hinh 2 cd STATCOM- PWM duoc thilt kl nhu hinh 12.
Hinh 12, Cdu true sa do mo phong bdng Matlab luai dien kin c6 STATCOM-PWM Tren hinh 12, vj tri kit noi STATCOM-PWM dupc tinh chgn tai nut A. Cac myc tieu ciia thiet ke dgt dupc the hien qua cac ket qufi md phdng nhu sau:
Hinh 13: Khi STATCOM chua hogt ddng, d che dp ddi xung trong khoang tir (0-5)s, dudng day L3 hfiu nhu kbdng tfii.
Vf\n\iU. DCS tren L3 Hinh 14a: Sau thdi dilm 5s, khi phu tfii Sb (hofic Sc) cd biln ddng (gifi thilt ddng tfii 5MVA), dien ap tgi cfic mit thay doi, tuang ling DCS tren cfic dudng dfiy thay ddi. Khi dd
Ngd Due Minh Tgp chi KHOA HQC & CONG NGHE 122(08). 3-8 STATCOM se bii cdng sufit phfin khfing Q
tren dudng day L2 de bii (tang) fip tai niit A, do dd sg tang them khofing L5MW lugng DCS tfic dyng P truyin tai tren L3 tir A din B, cdng nfing thiet kl ciia dudng dfiy L3 dupc dua vfio kbai thac. Kit qua md phdng thay rd khi so sfinh vol hinb 14b khdng cd STATCOM. Tuy nhien, mirc bii ciia STATCOM da dugc tinh theo gidi ban phat ndng ciia dudng dfiy L2, ddng thdi cd ke tdi sy phdi bgp ciia LI.
-v—y-
Hinh 14c. DCS tren L2 khi khong CO STATCOM Mfit khfic, STATCOM cdn cd y nghTa on djnh dipn fip nut vfi do dd dn dinh DCS khi dien ap bi kich dpng tir phia ngudn. Gia su dien fip ngudn Nl thay ddi nhu bang 3
Bang 3. Dien dp nguon Nl thay doi
Thtri gian (s) Di^n ip ngu6n N l tpu)
0 1 0
0 20 1 08
0 30 0 92
04 1 0
Ket qua md phdng thu dugc chi ra tren hinh 14a, hinhl4b vfi hinh 14c. Sd lieu cy the do dugc tren bfing 4 cho thfiy miic dao ddng dien ap tgi diem A khi khdng cd STATCOM ldn ban 5 lan so vdi khi cd STATCOM (0,13/0,025), hinh 14a. tucmg iing so sfinh mirc dao dgng DCS tren dudng dfiy L2 Ifi 3 lan (1,57/0.5) hinh I4b,c.
Hinh 15: Ddng di^n bii cua STATCOM ludn cd dgng sin (khdng bj meo) ke ca khi ddi chilu ddng bii tgi thdi diem 0.3s chuyen tir
ddng dien cfim chgm sau dien ap 90*^ sang ddng dien dung vugt tnrdc dien fip 90°.
Bang 4. Mice dao dgng dien dp vd DCS
Dircmg day L2
STATCOM Co STATCOM Dao d9ng dif n dp Dien ap max (pu)
Dien ap min (pu) Bien io dao dong
1,07 0.94 0,13
1,00 0,975 0.025 Dao aOng DCS DCS max (pu)
DCS min (pu) Bien dp dao d<ing
5,67 4,20 1,57
4.8 4 3 0,5
Hinh 15. Dong dien bit cua STACOM-PWM Hinh 16: Ddng va ap tren L3 thay ddi lien tyc nhung vfin khdng meo dgng, dam tdt tieu chufin chfit lugng dien nang trong truyen tfii.
'mimmmim m Ml
Hinh 16. Dien dp vd dong dien tren L3 KET LUAN
Ndi dung bai bao da cd dpng khdi lugng kien thirc tdng hgp rdng rai tir nhieu ngudn tai lieu chuyen ngfinh He thdng dien thdng qua viec phan tich mdt sd hogt dpng co bfin cua mdt ludi dien kin, nhung iing dung cua FACTS Md hinh nghien ciiu don gian nhung lai dam bao tinh tdng quat, tinh ke thira vfi tinh phat trien.
Tfic gifi hy vpng dfiy la san pham ddng gdp them cho ngudn tai lieu tham khao ddi vdi cfic sinh vien, hpc vien chuyen ngfinh he thdng dien. Qua day dd cung cd nhieu cfiu hdi cd the duac dgt ra, vi dy: Trong thuc te, neu nhirng dogn dudng day cao ap Udm >110 kV vdi chieu dfii hfing tram km (L4 > 100km), khi DCS tac dung bang 0 thi dieu gi xay ra? Tinh kinh te - ky thufit nhu the nfio''
Ngd Dlic Minh Tgp chi KHOA HQC & CONG NGHE 122(08): 3 - 8 Phgm vi bfii bfio nay tac gia mdi chi dl cap din FACTS Modelling and Simulation in Power mdt ylu to finh hudng din phan bd DCS trong V^f^^"^*"; „ c . o» ur*. An >^i
•' e- K , ^ =• 4. p.Kundur, Power System Stability and Control, ludi dien kin la dien ap niit. Nhung yeu to khac 5 ^ ^^.j^^^ V.G. Agelidis, O. Anaya Lara, T.J.E.
se dupc dl cap trong bfii bfio tilp theo. Miller. Power Electronic Control in Electrical Systems.
TAI LIEU THAM KHAO 6. Ngoducminh, Letienphong. Application of 1. Xiao-Ping Zhang,' Christian Rehtanz, Bikash bidirectional power converters to overcome some Pal. Flexible AC Transmission Systems: disadvantages of SVC substation. Joumal of Modelling and Control. Energy and Power Engineering, USA 2. Naiain G. Hingorani, Laszlo Gyugyi. 7. Giroux P., Sybille G., Power System simulation Understanding FACTS_ Concepts and Technology Laboratory, IREQ Hydro-Quybec.
ofFlexible AC Transmission Systems. 8. Ph.D. Thesis, M.Sc. Mariusz Malinowski.
3. Enrique Acha, Claudio R. Fuerte-Esquivel, Sensorless Control Strategies for Three - Phase Hugo Ambriz-Pe'rez, Ce'sar Angeles-Camacho. PWM Rectifiers. Warsaw, Poland 2001.
SUMMARY
ANALYSE CLOSED GRID AND APPLY FACTS TECHNOLOGY TO CONTROL POWER FLOW
Ngo Due Minh College of Technology - TNU This paper combines the traditional method to analyse grid and Matlab simulation that present basic operations of power system in a simple model using FACTS technology. Main contents include: Building a typical ciosed grid model provided from standard diagram of IEEE to serve many different researches; Analysing grid, evaluating factors that affect on power flow in grid, and considering a particular factor being node voltage; Using STACTCOM-PWM in FACTS technology to compensate reactive power in grid to adjust node voltage and power flow on the line; Simulating closed grid in Matlab/Simulink having STATCOM-PWM in forming multilevel inverter; Analysing and evaluating received research results and proposing further researches.
Keywords: Closed grid. DCS. STATCOM-PWM. node voltage, multi-level. FACTS
Ngdy nhdn bdrO 1/7/2014. Ngdy phdn bien. 31/7/2014; Ngdy duyet ddng: 25/8/2014 Phdn bien khoa hpc: TS. Nguyin Due Tuang - Truang Dgi hoc Ky thugt Cdng nghiep - DHTN
