Bai Dich EMC

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<p>Tng thch in t trong h thng ngun</p> <p>GVHD: TS. Tng Tn Chin</p> <p>EMC (ELECTROMAGNETIC COMPATIBILITY) TNG THCH IN T TRONG H THNG NGUN SCHNEIDER ELECTRICVi tt c cc thit b s dng in, EMC phi c xem xt mt cch c th</p> <p>ngay t giai on thit k ban u v nhng nguyn l, quy tc khc nhau tip tc c xuyn sut qu trnh sn xut v lp t thit b. iu ny c ngha rng tt c rt phc tp, t nhng k s v nhng kin trc s m thit k mt ta nh n nhng nh k thut thi cng dy in trong cc t thit b in, bao gm nhng chuyn gia thit k mng trong cc ta nh v nhng kp, i xy lp cc thit b, phi c quan tm n EMC Mt qui tc c chp nhn l "Sng ha bnh " cng vi s tn ti ca cc nhy ca thit b vi nhng nhiu lon in t trng (m thnh ra c xem xt nh l " i tng b nh hng ") dc theo thit b pht ra nhng s nhiu lon nh vy (trong nhng t khc, gi l " ngun " ca nhng s nhiu lon) Tp ti liu ny c bin son qua nhiu nm c kt kinh nghim ca Cng ty Schneider Electric, gii thiu nhng s nhiu lon thng gp v cung cp vi phng php thc hnh b p s nhiu lon .</p> <p>Ni dung1. GII THIU 1.1 Tng thch in t - EMC - Nhng c trng v qui tc 1.2 Ngy nay, EMC l rt cn thit. 1.3 s phc tp ca l thuyt EMC 2. NGUN 2.1 Tm quan trng ca vic nhn dng h thng ngun 2.2 V d s nhiu lon vt dn in ca ngun lin tc trong in nng 2.3 V d bc x ca nhng nhiu lon ngun: ngn mch trong cc trm bin p MV v VHV 3. GHP NI 3.1 S khc nhau ca cc kiu ghp ang tn ti 3.2 Cc kiu trng chung hoc khc nhau lin quan ghp ni dy 3.3 Ghp tr khng chung 3.4 Cc kiu khc nhau ca vic ghp ni dy hoc bng xuyn cho 4. CC H HNG 4.1 Cc li thit b 4.2 Cch gii quyt vn 5. CI T 5.1 Ci t mt s h s quan trng trong ton b h thng EMC 5.2 Giai on thit k 5.3 Giai on ci t 5.4 V d thc hnh 6. TIU CHUN, KIM TRA THIT B V KIM TRA TON B 6.1 Tiu chun 6.2 Kim tra thit b 6.3 Kim tra 7. KT LUN Sinh vin thc hin: Trn Thanh Sn (T-VT 2006-2009) Trang 1</p> <p>Tng thch in t trong h thng ngun Ti liu tham kho chnh:</p> <p>GVHD: TS. Tng Tn Chin</p> <p>1/ Gio trnh mn hc: Tng thch in t v sng in t trong cc h nh hng 2/ Cahier technique no. 149; EMC: electromagnetic compatibility of SCHNEIDER ELECTRIC Ti liu nghin cu: 1/ Introduction to Electromagnetic Compatibility; Second Edition CLAYTON R.PAUL Department of Electrical and Computer Engineering, School of Engineering, Mercer University, Macon, Georgia and Emeritus Professor of Electrical Engineering, University of Kentucky, Lexington, Kentucky A JOHN WILEY &amp; SONS, INC. PUBLICATION 2/ Power Quality Application Guide Earthing &amp; EMC Fundamentals of Electromagnetic Compatibility (EMC) of Copper Development Association</p> <p>Sinh vin thc hin: Trn Thanh Sn (T-VT 2006-2009)</p> <p>Trang 2</p> <p>Tng thch in t trong h thng ngun 1. GII THIU</p> <p>GVHD: TS. Tng Tn Chin</p> <p>1.1 Tng thch in t - EMC c trng v qui tc: EMC l mt c trng ca thit b hoc nhng h thng m t chng li nhng s pht x in t tng ng ca chng. Theo T Vng K Thut in Quc t (International Electrotechnical Vocabulary) IEV 161 -01-07, EMC l kh nng ca mt thit b hoc h thng lm chc nng tha mn trong mi trng in t trng ca n m khng cho nhng s nhiu lon in t qu qut lm quen vi bt c ci g trong mi trng . Ngy nay, EMC cng l mt qui tc c tp trung vo ci thin s ng tn ti ca thit b hoc nhng h thng m c th pht ra s nhiu lon in t v / hoc c cm ng ti chng. 1.2 Ngy nay, EMC rt cn thit Nhiu thit b v nhng h thng lun lun b l thuc ti s nhiu lon in t, v bt k thit b k thut in no, chnh n, t nhiu l mt my pht nhiu lon in t. Nhng s nhiu lon ny c pht sinh bng nhiu cch. Tuy nhin, nguyn nhn chnh gy ra chnh l nhng s bin i thnh lnh ca dng in hoc in p. Phn ln nhng s nhiu lon in chung nht (xem hnh 1) trong vng in t ca in p thp c tho lun trong "Cahier Technique "s 141". Cahier Technique "s 143 tho lun v nhng s nhiu lon pht sinh khi thit b hot ng ti mc in p chuyn mch l trung bnh. Lp Nng lng cao Tn s trung bnh Ngun gc - Chuyn mch ngun cng sut Nhng s st p - Nhng b ngn mch - Khi ng cc mt cng sut cao - Cc h thng vi bn dn cng sut iu ha - L h quang in - St nh trc tip hoc gin tip - B chuyn mch ca thit b iu khin Qu p - Ngt cc b ngn mch ca cc b bo v Hin tng phng in ca trng tnh Phng in tnh in in trong c th con ngi Hnh 1:Nhng nhiu lon chung nht Kiu</p> <p>Tn s cao</p> <p>Nhng s nhiu lon ny c th c truyn lan do s truyn dn dc theo nhng si dy cp hoc c bc x trong cc hnh thc sng in t. Nguyn nhn gy ra s nhiu lon c m t bng cc hin tng di y. Hai v d l giao thoa ca sng v tuyn v giao thoa vi nhng h thng iu khin v o lng gy ra bi nhng s pht x in t. Trong vi nm gn y, vi khuynh hng cng nhau lm cho EMC tr nn quan trng hn bao gi, l : * Nhng s nhiu lon ang tr nn mnh hn vi gi tr in p v dng in ngy cng tng . * Nhiu mch in t ang gia tng s dng cc b cm bin. Sinh vin thc hin: Trn Thanh Sn (T-VT 2006-2009) Trang 3</p> <p>Tng thch in t trong h thng ngun</p> <p>GVHD: TS. Tng Tn Chin</p> <p>* Khong cch gia nhng mch cm ng (thng l in t ) v nhng mch gy nhiu (nh nhng mch cung cp ngun in) ang tr nn nh hn. Trong s pht trin ca nhng sn phm , nh h thng chuyn mch bo v Merlin Gerin (hnh 2), Schneider Electric thy trc nhu cu cn hiu bit v p dng nhng nguyn l EMC. Trong h thng thit b ng ngt v iu khin hin i, dng in thp v cao, b iu khin v cc b ngun in t, b bo v in t v nhng thit b cung cp in tt c c b tr tng i gn.</p> <p>Hnh 2 : V d ng dng EMC : mc in p trung bnh panel SM6 cha mt cu dao in c thit k ngt b ngun (vi dng in hng trm ampe in p di hng chc kilvn), v mt chng trnh SEPAM iu khin, b theo di v bo v. T hp thit b hon thin phi c chc nng n nh di tt c mi trng hp. Do vy EMC l mt tiu chun c bn phi c xem xt trong tt c cc khu pht trin v sn xut sn phm, cng nh trong thi gian lp t v u ni dy. Hn na, by gi EMC bao gm mt trong nhng tiu chun v ang tr thnh mt yu cu hp php. Nhng kinh nghim v thnh tu ca Schneider Electric th khng gii hn i vi vic tha mn chc nng ca cc h thng in v/hoc in t trong mi trng in t thng thng ca n: v d, Merlin Gerin thit k v xy dng thit b c kh nng chng c nhng iu kin khc nghit nht nh s bc x in t pht sinh bi cc v n ht nhn cao . 1.3 L thuyt EMC th phc tp Bt k cng vic no lin quan n EMC dn n vic phn tch ba thnh phn sau: Sinh vin thc hin: Trn Thanh Sn (T-VT 2006-2009) Trang 4</p> <p>Tng thch in t trong h thng ngun-</p> <p>GVHD: TS. Tng Tn Chin</p> <p>S gy nhiu ca my pht hoc ngun - Truyn lan hoc ghp ni - Thit b hoc h thng b nh hng hoc cc i tng b nh hng khc Ni mt cch chnh xc, ba thc th khng phi l c lp nhng tt c cc mc ch thc hnh u c gi thit ti. S phn tch l thuyt th kh khn bi v n lin quan n s truyn lan ca sng in t trng c m t bi mt tp hp phng trnh vi phn phc tp c gi l nhng phng trnh ca Maxwell. Ni chung, chng khng th c gii quyt nhng b mt gii php phn tch cho nhng thit b v nhng kch thc thc t. Thm ch vi nhng h thng my tnh mnh, gii php s thng rt kh thu c hiu qu. Trong thc t, nhng vn EMC phi c cp vi cc gi thit c n gin ha, vic s dng nhng m hnh v c bit l cc phng th nghim v a n cc phng php o. 2. NGUN NHIU 2.1 S quan trng ca vic nhn dng ngun Nhn dng v o th ngun th quan trng mt khi nm chc kiu ngun s xc nh nhng php o sau. - Gii hn ca nhng s nhiu lon pht sinh (E.g. trn mt cng tc, bng vic lp t mt mch cng hng n v RC song song vi ngun AC. Li dy, hoc mt it trn li dy ngun DC) - Trnh s ni cho (i.e. v mt vt l phn ra hai phn t khng tng thch cao) - Kh nhy nhng i tng b nh hng tim tng (e.g. s dng v cch ly) Cc tc nhn gy ra chnh: Bt k thit b hoc hin tng vt l /in pht ra s nhiu lon in t trng, hoc cc dy dn hoc bc x, gi l ngun nhiu. Nguyn nhn chnh gy ra s nhiu lon in t l s phn phi cc b ngun in, sng v tuyn, s phng in t v st nh - Phn phi ngun in, mt s ln s nhiu lon c to ra bi chc nng chuyn mch Trong vng in p thp, vic m nhng mch in cm nh nhng cun dy cng tc, nhng m t , nhng van cm ng t .v.v. pht sinh nhng xung in p rt cao (ln ti vi kV ngang qua nhng thit b u cui cun dy) m cha ng hi tn s cao (ti hng trm MHz). Trong vng in p cao hoc trung bnh, vic m v ng b ngt ni sn sinh nhng sng vi mt nhp rt nhanh (mt vi nan-giy). Nhng sng ny th c hi c bit ti nhng h thng trn nn b vi x l. - Sng v tuyn pht ra bi nhng h thng theo di t xa, iu khin t xa, truyn thng v tuyn, nhng my truyn hnh, nhng my b m .v.v. chnh l ngun gy ra s nhiu lon trong th t vi V/m. Ngy nay, tt c nhng my pht gy nhiu lon ny th ni chung ngy cng tng v d nh hng n thit b bi vy cn c cung cp ngy cng tng hiu qu bo v. - Mc np in ca c th con ngi : cho v d, mt ngi i b trn mt kiu thm trong mt kh hu kh v lnh c th c np ln trn ti hn 25 kV! Bt k tip xc vi sn phm thit b in t no u sn sinh mt s gii phng vi mt Sinh vin thc hin: Trn Thanh Sn (T-VT 2006-2009) Trang 5</p> <p>Tng thch in t trong h thng ngun</p> <p>GVHD: TS. Tng Tn Chin</p> <p>thi gian rt nhanh (vi nan-giy) c np vo thit b bi s kt ni v bc x, pht sinh s nhiu lon chnh. Nhng c trng ca s nhiu lon Ngun c th c nh trc (E.g. my pht v tuyn) hoc khng c nh trc (e.g. n v hn h quang in). Tuy nhin ni chung chng c th c phn bit bi nhng c trng ca nhng s nhiu lon do chng sn sinh : - Ph - Dng sng thi gian ln hoc bao ph ca ph - Bin - Nng lng Ph, bng tn s b bao trm bi s nhiu lon c th rt hp, nh trng hp ca h thng in thoi di ng , hoc rt rng, nh nhng l h quang in. Nhng s nhiu lon kiu xung bao trm mt b rng ph c bit ln ti 100 MHz hoc hn (xem hnh 3). Ti loi cui cng ny phn ln thuc v ring ca ngun nh l: - S phng in ca trng tnh in - Chuyn mch r le, b ngt kt ni, cng tc, nhng chuyn mch v nhng cu dao in bn trong LV, MV v HV bng - St - Cc xung in t ht nhn (lnh vc c bit)</p> <p>Hnh 3: Nhng v d v nhng c trng ph ca tn hiu nhiu Mt khi mc ca s ghp ni trc tip cn cn i ti tn s, EMC s dng min tn s m t c im s nhiu lon. Kiu trnh by ny ,cho mt tn hiu tun hon, th tng t nh mt chui Fourier (bao gm tng ca cc hi). Sinh vin thc hin: Trn Thanh Sn (T-VT 2006-2009) Trang 6</p> <p>Tng thch in t trong h thng ngun</p> <p>GVHD: TS. Tng Tn Chin</p> <p>Dng sng m t nhng c trng ca s nhiu lon trong c thi gian v c th, cho v d, mt sng hnh sin tt dn hoc hm m gp i. N c biu th nh mt thi gian ln tr, mt tn s tng ng 0.35/tr hoc n gin l tn s nhiu lon cho tn hiu bng hp hoc nh mt bc sng c quan h vi tn s bi cng thc =c/f, trong c l tc ca nh sng (3 * 108 ms - 1). Bin l gi tr cc i ca tn hiu t n di dng in p (volt), lnh vc in (v/m ), etc. Nng lng l s nguyn ca mc nng lng tc thi trong c thi gian tn hiu nhiu ko di 2.2 V d ca mt ngun lin tc dn n s nhiu lon trong cc b ngun in t Trong cc b ngun in t, nhng ngun nhiu c bn hng ti l in p hn l nhng dng in tc thi. Nhng in p c th thay i hng trm vn thc t trong mt vi ns a dV/dts qu mc109 V/s.</p> <p>Hnh 4: Ngun nhiu lon trong cc b ngun in t: K thut chuyn mch iu ch rng xung a) L thuyt b) M rng xung(m rng t); mt phn ca sng hnh sin khng tng xng khi n bao trm 20 ms; tr 2 to 3 tf (10 ns to 1 s) iu ch rng xung (PWM) (xem hnh 4), v d, pht sinh mt in p sng hnh sin t mt in p DC, vic in p thay i t 0 n Udc (660 V cho ngun ba pha) xut hin trong mt thi gian rt ngn, ns ti vi s ph thuc vo cng ngh c s dng. in p thay i nhanh chnh l ngun ca nhiu hin tng nhiu lon, phn ln s nghi vn da vo kinh nghim, pht sinh nhng dng chy xuyn qua bt k nhng in dung k sinh no. Dn n in dung k sinh Cp c tnh n, dng in tnh chung nh sau: ICM = Cp dV/dT. Vi nhng thi gian ln c cp sm hn, mt in dung k sinh 100 pF th pht sinh dng in ch chung ca vi trm mA. Dng nhiu ny s chy Sinh vin thc hin: Trn Thanh Sn (T-VT 2006-2009) Trang 7</p> <p>Tng thch in t trong h thng ngun</p> <p>GVHD: TS. Tng Tn Chin</p> <p>xuyn qua dy dn tiu chun zr v c th sa i nhng tn hiu (d liu hoc nhng cu lnh), c chng ln nhy php o v quy ry thit b khc bi vic a tn hiu nhiu vo trong mng phn phi cng cng. Mt cch b tr hin tng ny, i.e. bo m EMC, tng thm thi gian ln in p. Tuy nhin mt gii php nh vy gia tng ng k s mt mt cc chuyn mch trong nhng tranzito, sn sinh nhit c hi. Cch khc lm gim bt nhng dng in ch chung c hiu qu khc gm c tng thm tr khng ch chung. Cho v d, khi ghp nhng thnh phn b ngun in t, c hai phng php sau th thng s dng : _ Ngt b tn nhit (khng kt ni in), (xem hnh 5), nu nhng qui tc an ton th cha b xm phm.</p> <p>Hnh 5: in dung k sinh ca b tn nhit(thnh phn lm mt) c k n trong vic thit k UPS - Gim bt in dung k sinh gia thit b v b tn nhit s dng mt vt cch ly vi mt hng s cht in mi thp (xem hnh 6).</p> <p>Hnh 6: Cc kiu cht cch ly c s dng khi lp cc thnh phn in t</p> <p>Sinh vin thc hin: Trn Thanh Sn (T-VT 2006-2009)</p> <p>Trang 8</p> <p>Tng thch in t trong h thng ngun</p> <p>GVHD: TS. Tng Tn Chin</p> <p>Trong lnh vc h thng UPS (ngun lin tc) chng hn, cc bin php phng nga trn lm khc i gia h thng " lm nhim " v mt h thng " sch ". Cho nhng h thng UPS, ch rng in t mc thp trong b o tnh phi c bo v chng li nhng s nhiu lon c to ra bi nhng mch in ngun ca chnh mnh. Tht cn thit hiu v iu khin hin tng ny gii hn nh hng ca s pht x c hiu qu v tit kim. Nhng ngun t thng xuyn hn khc tn ti nh st v chuyn mch t bin c th pht sinh dV/dts v dI/dts ln. S nhiu lon ny cng pht sinh bc x nhng trng. 2.3 V d ca ngun nhiu bc x : ng mch trong trm MV v VHV Mi trng trm, c bit trong nhng ng dng in p trung bnh v rt cao, c th cha ng nhng min c xung in t trng rt mnh. Nhng thao tc ng ngt nht nh c th pht sinh nhng in p cao hn nhiu gi tr danh nh trong mt thi gian rt ngn. Cho v d, khi mt chuyn mch 24kV c ng, hin tng nh la gy ra nhng s bin i in p hng chc KV trong mt vi ns. Phn ny s c bn lun chi tit hn trong "Cahier Technique no 153 :"SF6 Fluarc circuit breakers and MV motor protection" Nhng php o thc hin nhng phng th nghim Schneider cho thy trong thi gian chuyn mch 24 kV ng ngt, min hnh sin tt dn t n nhng gi tr nh 7.7 kV/M vi tn s 80 MHz khong cch 1 mt t t chuyn mch. Sc mnh ca min ny th qu ln khi so snh vi mt 1W cng sut pht ca my b m song cng m pht sinh 3 n 5 V/m o ti khong cch ca 1 mt. in p c truyn lan dc theo dy dn, nhng thanh gp, cp v dy trn. Tn s th phc tp, i.e do hin tng xy ra nhanh, nhng dy dn (c bit l nhng thanh gp) vn hnh nh anten v nh c trng lnh vc trng in t chng pht ra th ph thuc cao vo thit k ca nhng thng kim loi (vng phn chia con, t chuyn mch). Trong nhng trm in p rt cao c lp bc kim loi, trng in t th c bit mnh. V bc kim loi SF6 cch ly trm c hnh dng ng trc v bi vy n lun th hin tr khng c trng khng thay i. in p thay i nhanh bn trong kim loi c th ngn vic pht sinh hin tng sng ng; chng c to ra do xut hin phn x lc tr khng b thay i. Cng v thi gian ca hin tng cng c tng bi hiu ng ny. Mi trng in t vng in p trung bnh v rt cao yu cu nghin cu tng thch in t su hn thit k v lp t nhng h thng r le, nhng thit b iu khin v b kim tra. iu ny th c bit quan trng v phi thm vo bc x nhiu. (xem hnh 7)</p> <p>Sinh vin thc hin: Trn Thanh Sn (T-VT 2006-2009)</p> <p>Trang 9</p> <p>Tng thch in t trong h thng ngun</p> <p>GVHD: TS. Tng Tn Chin</p> <p>Hnh 7:3 v d thit b vi in t s c pht trin bi Schneider Electric c thit k y tng thch in t trng 1- A SEPAM c tch hp n v bo v v iu khin trong thit b MV 2- n v bo v v iu khin cho b ng ngt Masterpact 3- ANTIVA 66 iu khin tc 3 GHP NI 3.1 Tn ti nhiu kiu ghp ni khc nhau: S ghp ni ni n s lin kt, s chuyn i hoc truyn lan ca nhng s nhiu lon trng in t t my pht n i tng b nh hng. S ghp ni c biu din di dng h s ghp ni k, n v l dB (e.g 75dB), m c th nh gi nh hng truyn dn tn hiu nhiu lon t ni pht n i tng b nh hng .</p> <p>Sinh vin thc hin: Trn Thanh Sn (T-VT 2006-2009)</p> <p>Trang 10</p> <p>Tng thch in t trong h thng ngun</p> <p>GVHD: TS. Tng Tn Chin</p> <p>(k = 20 log A (received)/A (transmitted), vi A l cng ca tn hiu nhiu) H s k ch c nhiu ngha khi chuyn i s nhiu lon in t sang tn s, m thng l trng hp trong thc hnh. Ba kiu ghp ni ni ting c th c phn bit - Ghp ni trng vi dy theo kiu chung v kiu vi sai - Ghp ni tr khng...</p>