N NH TC CA TRUYN NG INChng 4N NH TC CA TRUYN NG IN Nguyn l chung n nh tc ng c in mt chiu dng phn hi dng dng ti n nh tc ng cmt chiu dng phn hi m in p n nh tc ng c mt chiu dng phn hi m tc n nh tc ng c d bNguyn l chung Nguyn l chung Trong qu trnh lm vic ca cc h thngtruyn ng in nhiu h thng i hi phi nnh tc nng cao cht lng sn phmv nng sut ca thit b. Mt khc n nh tc ca truyn ng in cn c kh nng mrng di iu chnh tc v tng kh nng quti cho ng c in.Nguyn l chung Nguyn l chung ci thincc ch tiu cht lng ca h thngtruyn ng in iu chnh, ngi ta thng thchin cc phng php iu chnh t ng, to ra khnng bin i thng s iu chnh (thng s u voXc) mt cch lin tc theo mc thay i ca thngs c iu chnh u ra (i lng X). Mun vy,ta phi thit lp h iu chnh vng kn, ly tn hiuphn hi t u ra trc tip t l vi i lng X hocgin tip qua cc i lng lin quan n X, cho tcnglnthng s uvo, lmchothng snythay i t ng theo chiu hng a i lng Xt n gi tr t trc.Nguyn l chung Nguyn l chung Cu trc chung ca h thng iu chnh tc vng knNguyn l chung Nguyn l chungTrong : U : tn hiu t, t l vi gi tr t ca thng s ciu chnh: tc . Uph: tn hiu phn hi, t l vi gi tr thc ca thngs c iu chnh . U = Udk: tn hiu sai lch, phn nh mc sai lchgia gi tr thc ca thng s ra vigi trmongmun t trc . Uk chnh l tn hiu dng iu khin phn t iuchnh Ch sao cho thng s ca n t ng thay i,v tc ng vo ng c () lm cho gi tr tin n .Nguyn l chung Nguyn l chung Bin php ch yu n nh tc l tng cngca c tnh c bng iu khin theo mch kn. Cc c tnh ca h h c: trong ton diiu chnh.constRK= =2) (Nguyn l chung Nguyn l chung Sai s tnh sai s tnh S Scpcn tm bin php tng tc n e = emin. Ta c im lm vic [emin ;Mm], ng c tnh c cng mong mun l |mv: Giao im ca c tnh mong mun vi c tnhca h h cho bit gi tr cn thit ca Eb khi Mcthay i:cpmSMS > =min 0. mM =min 0Nguyn l chung Nguyn l chungc tnh xc nh Ebkhi ti thay i.n nh tc ng c in mt chiu dng phn hi dng dng tiS nguyn l h thng Qui lut thay i Ebtheo dng ti n nh tc ng c in mt chiu dng phn hi dng dng ti c tnh c h h: MKEmb =. Ti giao im ca 2 ng ny ta lun c:m mbM MKE = 0I K E M K Ed bmm b'0 0)]1 1( [ + = + = Kdgi l h s phn hi dng.)1 1( ) (2 'mm dK K = c tnh c mong mun:mM =0(4.1)n nh tc ng c in mt chiu dng phn hi dng dng ti S nguyn ln nh tc ng c in mt chiu dng phn hi dng dng ti Theo s , ta c) ( ) (i b d b bU U K I R U K E + = + = T rt ra phng trnh c tnh c ca h nh sau:IKR RKI R U KIKR RKEdmddmd d ddmddmb ++=+ =) (IKR K RKU Kdmd ddmd d ) 1 ( + =U: in p t tc Ui: in p phn hi dng inRd: in tr shunt trong mch phn ng(4.2)(4.3)n nh tc ng c in mt chiu dng phn hi dng dng ti T (4.1), (4.2) c:( )( )d dmd b d b bR K RKR K KU K E + ===1..2'0 Nu chn Kd.Rd = R+Rdth c tnh c cng tuyt i. Nu chn Kd.Rd > R+Rdth c tnh c cng dng. Nu chn: Kd.Rd < R+Rdth c tnh c cng m.n nh tc ng cmt chiu dng phn hi m in p Qui lut thay i Ebtheo in p phn ngPhng trnh c tnh tnh ca b bin i BD c dng sau: Eb = U + RbIu Thay Rb = R - Ruta c:Thay (4.5) vo (4.1) ta c: )1 1( ) (2tndmbubuKU ER RU EI ==)1 1( ) (2'tndmbd bo bKU EK E E + =(4.4)(4.5)(4.6)n nh tc ng cmt chiu dng phn hi m in p Thay Kdvo (4.6) rt gn v t: Ta c: Kagi l h s phn hi in p.bbKbE E ba bo botn m== =1,11),1 1)(1 1(' ' U K E Ea bo b' ' =n nh tc ng cmt chiu dng phn hi m in p S nguyn ln nh tc ng cmt chiu dng phn hi m in p Nu b qua dng qua r1, r2v t Ka= r2/ (r1+ r2), ta c: T ta c phng trnh c tnh c ca h nh sau:) ( U K U K Ea d b b =b au b a d bu b b a d b bK KI R K U KI R E K U K E++= =1) ()} ( {MKRK KK KRK K KU KIKRKEdmba ba bdm a bd budm dmb2) (1) 1 ( ++= =n nh tc ng cmt chiu dng phn hi m in p Nu mch c Kb.Ka>> 1 th c tnh c dng:tna ddmua dmdMK U HayMKRK KU = =) , (.) ( . .02n nh tc ng cmt chiu dng phn hi m tc Qui lut thay i Ebtheo tc quayS nguyn ln nh tc ng cmt chiu dng phn hi m tc T phng trnh c tnh tnh ca b bin i B: Eb - Eu = Iu(Rb + Ru), Rb = R - Ru Ta c: Thay (4.7) vo (4.1) ta c: 1) (2dmdm bu bdm buKK ER RK EI=+=d dmdm dd dmdmbodmdm bd bo bK KK KK KKEKK EK E E=+ = / ) ( / ) (/ ) (1) (2 222 ' ') 1 (t bo dmm mbo bK E K E E = =Ktgi l h s phn hi tc :dmmtK K ) 1 (' =(4.7)n nh tc ng cmt chiu dng phn hi m tc c tnh c Ta c: ) ( t d b bK U K E =udm dmt d budm dmbIKRKK U KIKRKE = =) (ub t dm b t dmd bIK K KRK K KU K++= MK K K KRK K KU Kdm b t dm b t dmd b ) ( ++=n nh tc ng cmt chiu dng phn hi m tc Nu Kb.Kt t h | .n nh tc ng c d b n nh tc ng c d b Nguyn l iu p n nh tc dng phn hi m tc n nh tc ng c d b n nh tc ng c d b Nguyn l iu p- tn s n nh tc dng phn hi m tc v phn hi dng dng in