[GHIEN CUU SU ANH HUONG CUA CAi HIET Bl DIEN TU C 6 N G S U A T DEN
LaCll OIEN XY NGHIEP CONG NGHIEP
P G S . T S . G V C C . T H A I D U Y THl/C thuc_ thaiduy<i>yahoo.com Trudng Dgi hoc Md - Dia chdt.
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Noi dung bai bao de cap tdi nhiimg tac hai do cac thiet bj dien tiJT cong suat gay ra tren ludfi dien cua cac xy nghiep khi suf dung chiing ;d6ng thai gioi thieu phUOng phap xac dinh pho tan cua cac song lial bdc cao do cac thiet bi do gay ra tren liTori va cic gidi pliap loai bi cliung.
Abstract
The content of the paper refers to the harm caused by the power electronio devices on the grid caused latrines of the industry to use them at the same time introduce the method of determining the spec- trum of the harmonic high due to the device that caused the net and solutions to remove them
1. NGUY£N NHAN XUAT HIEN CAC SONG HAI BAC CAO TRONG LU(S\ D I I N CUA XY NGHIEP.
• • • He thdng cung cap didn cua cic xf nghidp ngay cang
hidn dai, trang bj ngiy cang nhilu eie thilt bj didn td cdng suit nhu biln t i n , khdi ddng mim, chinh lUu, Id didn hd quang... Vide trang bj thdm cac thilt bj dd da cii thidn he thdng truyin ddng cd chat lUpng tdt hPn, t i l t kidm nang lupng didn hpn... Tuy nhidn khi sd dung cing nhieu thilt bj didn td edng suit trong lUdi didn cd nhdng han ehl gi, phupng phip khie phuc ?
Chiing ta bilt ring mpt ham ehu ky theo thdi gian f(cut) nao dd thda man eie dilu kidn Dirickle cd t h i khai triln thanh chuoi Phurie:
fiat) = 00-1- Z , ^ ( a i coskot -H 6^ sin ia»t) (1)
Trong 36: Og - thSnh ph§n m0t chlSu i — s6 b#c ciia bdi
o,-,fcj - cdc h§ s6 ciia chu6i Phurie
Khi /=1la hai bac 1 hay edn gpi l i hii cP bin, td bilu thdc (1) cho thay nlu didn i p ludi khdng sin thi trong lUdi didn sd xuat hidn cic song hii bic eao (gpi la nhieu).
B4 tfnh toan mdc hii bic cao trong lUdi didn do dang didn ap khdng sin giy ra rat phdc tap va khd khin. Tat nhidn hidn nay la md phdng bing phan m i m Simulink cCia Matlab.
2 NGHIEN COrU XAC DINH NHIEU DO
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GAY RA.Trong thUe t l ed rat nhilu loai chinh lUu nhU mdt pha, hai pha, bap ha, cd dilu khiln, khdng dieu khiln, ddi xdng, khdng ddi xdng... loai cd dieu khiln thi cdn phu thupc vio gdc dilu khidn a. Trong khudn kho bai bao nay ehl xet mpt loai ehlnh luu cau ba pha cd dilu khiln la loai pho biln trong cdng nghidp.
Trdn hinh 1 la so do md phdng loai chinh luu nay va phUPng phip xic djnh nhieu.
Hinhl: Sd d6 cdu true md phing chinh lUu cdu 3 pha
Automation Today / 4, 2012
41
Hinh 2: Diin dp 3 pha khdng tin
Trdn hinh 2 ddng didn ba pha trong ludi didn khdng edn sin nda. Vdi ddng khdng sin dd se gdm ddng cP bin sin va cic ddng cd tin sd cao khic. Phd tin eho trdn hinh 3 vi hinh 4. Vdi cic kdt qui phin tfch din bic 40 (hinh 3) vi bic 200 (hinh 4). TU hinh 3 vi 4 eho thiy trdn lUdi didn sd xuit hidn ddng didn tan sd cP bin hinh 250(Hz) vi eie ddng didn ed tan sd bic cao khic (bic 3,5,11,17,19...).
Nghia li cac ddng didn cd tin sd 150,250,550 Hz.... Hd sd TDH chilm cd 29.24%.
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Khdi ddng mim dang 6ugc sii dung nhilu 64 giim ddng khdi ddng ddng ep khdng ddng bd rdto Idng sdc cdng suit Idn. Tuy theo hing ehl tao va mdc dp ydu ciu mi cd thi dung loai ddi xdng hoic khdng ddi xdng. trong bii bao nay gidi thidu kit qui nghidn cdu cho loai khdi dpng mim doi xdng 64 giim ddng khdi dpng cua ddng cP Idng sdc cdng suat 45kW.
1
Sor do mo ph6ng cho tren hinh 5
Hinh 5: Sad6 md phdng tren Matlab
Ket qu<^ phan tich pho nhieu xuat hien tren ludi dien cho thay cac nhieu chinh t^c (bac le ) co bien do Id hon rat nhieu so vdi nhieu khong chinh tic. Nhieu bac 5 la Idn nhat sau do dang ke la dang ke la nhieu bac 3,7,11. He so TDH = 27.83% (hinh 6)
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4 NGHIEN ClTU XAC D I N H NHIEU DO BIEN T A N SINH RA TRONG iiJCfl DIEN
Tren hinh 7 cho so do mo phong bien tan dieu khien dpng CO khong dong bp roto long soc cong suat 200kW.
Bien tan 600V dupc dau a dau ra bien ap. Ket qua nno phong cho thay hinh anh dien ap nguon, dien ap thu'cap eua bien ap nhu hinh 8
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Tu ddng hoa ngay nay / 4, 2012
Hinh 8 Diin dp ngu6n vd diin dp thUcdp
Rd rang r i n g didn i p nay khdng cdn sin nda. Kit q u i phin tfch phd nhieu eho thay khi p h i n tfch d i n tan sd 1000Hz cho trdn hinh 9a. Khi p h i n tfch d i n tan sd 2000Hz cho trdn hinh 9b. Khi p h i n tfch d i n t i n sd 10000Hz cho tren hinh 9e.
TU eie k i t q u i trdn eho thay nhieu xuat hidn trdn dudng d i y t d b i l n ap d i n bien tan cd rat nhieu tan sd khac nhau va vdi bidn 66 khac nhau.
Dang ehu y nhat la c i c tan sd 25, 75,100,125,150,175,200,1375,1850,1875...Hz
Bien dp ddng t i i d 50Hz la 285,5A trong luc dd nhieu d 75Hz la 160,5A d 10OHz la 50,6A. Ngoai nhieu chfnh t i e cdn xuat hidn cic nhieu khdng chfnh t i c .
O l thay rd bidn dp nhieu chfnh t i c va khdng chinh t i e do biln tan g i y ra trdn ludi didn sau d i y thdng kd k i t q u i phan tfch cho 1000Hz dau tidn:
Qua cie nghidn edu tren eho thay pho tan bien dp cua nhieu do cic t h i l t bj didn t d cdng suit gay ra chda cac song hai chfnh t i c b i c 3,5,7,9,11,13,15... lan nhdng sdng hai khdng chfnh t i c 2,4,6,8,10...
Nguydn nhan cP b i n lam xuat hidn cie sdng h i i khdng binh thudng (khdng chfnh tic) la do sU khdng ddi xdng eua cac xung d i l u khiln. SU khdng ddi xdng do thudng gap d hau h i t cic he thdng d i l u khiln hien nay. Tuy nhidn bidn
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dp cua sdng h i i khdng binh thudng rat nhd so vdi bidn dp cua sdng h i i chfnh t i c .
Trong ludi didn cang sd dung nhieu t h i l t bj dien tU cdng suit thi nhieu cang Idn vl theo nguyen ly x i p chdng. Cic i n h hudng dd cing l i m mdo dudng cong didn i p eua lUdi.
Hau q u i cua vide dd la: lam t i n g nhu cau cdng suat vd cdng, lam tang ton that n i n g lupng trong ludi dien, lam gia hda nhanh cic may dien v i t h i l t bi didn, lam g i i m hidu q u i eua cic tu bCi cos va g i y q u i t i i cho cic tu bCi do, lam xau chat lupng dieu khiln cua cac he dieu khien t u dpng, gay nhilu cho he thdng thdng tin, lam tang sai sd do lUdng dien, cic loai role b i o ve, lam tang dong trong day trung tfnh.
5 K^T LUAN
Qua sU phan tich tren cho thay cac t h i l t bj dien t d cdng suat se lam cho meo dien ap ludi, tao ra cac ddng dien bac cao trong lUdi dien gay ra rat nhieu hau q u i xau.
Oe giam i n h hudng do tdt nhat la sd dung t h i l t bj lpc sdng hai bac cao. Cae t h i l t bj Ipc nay cd hai loai la Ipc thu ddng va lpc tfch cUc. Cac Ipc thu dpng cd hieu qua kem hPn nhieu Ipc tfch cue.
Oa d i n luc cac xf nghidp phai quan tam den van de Ipc nhieu khi ma trang bj ngay cang nhieu bien tan, khdi dpng mem. a
Tai lieu tham khio:
1. Thai Duy Thifc, Khong Cao Phong
Giao trinh dien t i l cong suat va ijfng dung trong cong nghiep m6 - D i u l<hi, NXB Giao ThongVan TSi -2006.
2. Nguyen Xuan Phu
SCf dung help ly tiet l<iem va hieu quci dien nang trong shn xuat va sinh hoat NXB-Khoa hpc va l<y thuat.
3. Simulinl< cua Matlab
4. Thii duy thufc, Ngo thj Thanh Nga
Nghien cijfu sU phat sinh nhieu trong qua trinh dieu chinh cong suat bu trong thiet bj dieu toe tSi g i i cua cic tram thuy dien nh6. Tap chi KHKT thuy loi va moi truong 2009
5. Nguyen Van Lien- Bien tan- NXB KHKT - 2004
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Hinh 9: Pho tdn dcic dii tdn sd
Automation Today / 4, 2012