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Parametri T: Quid sunt? (Exempla Problemataque et Quomodo Parametros T in Alios Parametros Convertantur)

Electrical4u
Campus: Electrica Elementaria
0
China

quid sunt parametri T

Quid sunt Parametri T?

Parametri T definuntur ut parametri lineae transmissionis vel parametri ABCD. In rete duorum portarum, porta 1 consideratur ut extremitas missiva et porta 2 ut extremitas receptiva. In diagrammate rete infra, terminales portae 1 repraesentant portam input (missivam). Similiter, terminales portae 2 repraesentant portam output (receptivam).



rete duorum portarum parametri T

Parametri T in Rete Duorum Portarum


Pro supradicta rete duorum portarum, aequationes parametrorum T sunt;


(1) \begin{equation*} V_S=AV_R + BI_R \end{equation*}



(2) \begin{equation*} I_S=CV_R + DI_R \end{equation*}


Ubi;

VS = tensio extremi emitterentis voltage
IS = currentus extremi emitterentis current
VR = tensio extremi recipientis
IR = currentus extremi recipientis

Hi parameteri utuntur ad creandum modello mathematicum lineae transmissionis. Parameter A et D sunt sine unitate. Unitas parameter B et C est ohm et mho, respectiviter.


  \[ \begin{bmatrix} V_S \\ I_S \end{bmatrix} = \begin{bmatrix} A & B \\ C & D \end{bmatrix} \begin{bmatrix} V_R \\ I_R \end{bmatrix} \]


Ad inveniendum valorem T-parameterorum, oportet circuitum receptoris apertum et circuitum brevem facere. Quando extremus receptoris est apertus, currentus extremi receptoris IR est nullus. Hunc valorem in aequationibus ponimus et obtinemus valores parameterorum A et C.


  \[ I_R=0 \]




conditio circuiti aperti


Ex aequatione 1;


  \[ V_S=AV_R + B(0) \]



  \[ V_S=AV_R \]



  \[ A = \left \frac{V_S}{V_R} \right|_ {I_R=0} \]


Ex aequatione II;


  \[ I_S = CV_R + D(0) \]



  \[ I_S = CV_R \]



  \[ C = \left \frac{I_S}{V_R} \right|_ {I_R=0} \]


Cum terminus receptoris brevi circuitu coniungitur, tensio inter terminos receptores VR est nullus. Hoc valore in aequatione posito, valores parametrorum B et D obtinere possumus.


  \[ V_R = 0\]




conditio circuiti brevis


Ex aequatione-1;


  \[ V_S=A(0) + BI_R \]



  \[ V_S = BI_R \]



  \[ B = \left \frac{V_S}{I_R} \right|_ {V_R=0} \]


Ex aequatione secunda;


  \[ I_S=C (0) + DI_R \]



  \[ I_S = DI_R \]



  \[ D = \left \frac{I_S}{I_R} \right|_ {V_R=0}\]


Exemplum Problema Solutum Parametrorum T

Consideretur impedimentum inter terminos emittendi et recipiendi ut in figura subiecta ostenditur. Inveni T-parametros datae rete.



t parameter example

T-parameter Exemplum


Hic, currentis emittendi est idem ac currentis recipiendi.


  \[ I_S = I_R \]



(3) \begin{equation*} I_S = (0)V_R + (1) I_R \end{equation*}


Nunc, applicamus KVL ad rete,


  \[ V_S = V_R + I_S Z_1 \]



  \[ V_S = V_R + I_R Z_1 \]



(4) \begin{equation*} V_S = (1)V_R + (Z_1) I_R \end{equation*}


Compare equation-1 and 4;


  \[ A = 1, \, B = Z_1 \]


Compara aequationes 2 et 3;


  \[ C = 0, \, D = 1 \]


Parametri T Lineae Transmissionis

Secundum longitudinem lineae, lineae transmissionis classificantur ut;

  • Brevissima linea transmissionis

  • Media linea transmissionis

  • Longissima linea transmissionis

Nunc, invenimus parametris T pro omnibus typis lineae transmissionis.

Brevissima Linea Transmissionis

Transmissio lineae brevior quam 80km et tensio minor quam 20kV consideratur brevis transmissio lineae. Propter parvam longitudinem et minorem tensionem, capacitatio lineae negligitur.

Itaque, consideramus tantum resistensiam et inductivitatem modelando brevem transmissionem lineae. Representatio graphica brevis transmissionis lineae est sicut in figura subiecta ostenditur.



t parameter of short transmission line

T-parametri brevis transmissionis lineae


Ubi,
IR = Current receptoriae extremi
VR = Tensio receptoriae extremi
Z = Impedentia oneris
IS = Current mittentis extremi
VS = Tensio mittentis extremi
R = Resistensia lineae
L = Inductivitas lineae

Cum currentus per lineam transmissionis fluat, IR cadit in resistensia lineae et IXL cadit in inductivitate reactantia.

Ex hoc reticulo, currentus mittentis extremi idem est ac currentus receptoriae extremi.


  \[ I_S = I_R \]



  \[ V_S = V_R + I_R Z \]


Nunc, compare istas aequationes cum aequationibus T-parametrorum (aequatio 1 et 2). Et obtinemus valores parametrorum A, B, C, et D pro brevi linea transmissionis.


  \[ A = 1, B = Z, C = 0, D = 1 \]


Medius Trames Line

Trames line habens longitudinem de 80km ad 240km et tensionem de 20kV ad 100kV consideratur ut medius trames line.

In casu medii trames line, non possumus neglegere capacitatem. Debemus considerare capacitatem dum modellemus mediam trames line.

Secundum locum capacitatis, medii trames lines classificantur in tres methodos;

  • Methodus Condensatoris Extremi

  • Methodus Nominalis T

  • Methodus Nominalis π

Methodus Condensatoris Extremi

In hac methodo, capacitatio lineae ad extremum lineae transmissionis conlocatur. Figura graphica Methodi Condensatoris Extremi infra demonstratur.



t parameter of end condenser method

T-parametri Methodi Condensatoris Extremi


Ubi;
IC = Currentus condensatoris = YVR

Ex figura supra,


  \[ I_S = I_C + I_R \]



(5) \begin{equation*} I_S = Y V_R + I_R \end{equation*}


Per KVL, possumus scribere;


  \[ V_S = V_R + Z I_S \]



  \[ V_S = V_R + Z (I_C + I_R) \]



  \[ V_S = V_R + Z (Y V_R + I_R) \]



  \[ V_S = V_R + Z Y V_R + Z I_R \]



(6) \begin{equation*} V_S = V_R (1 + ZY) + Z I_R \end{equation*}


Nunc, comparate aequationes-5 et 6 cum aequationibus parametrorum T;


  \[ A = 1 + ZY, \; B = Z , \;  C = Y , \;  D = 1\]


Methodus T Nominalis

In hac methodo, capacitatio lineae ponitur in medio lineae transmissionis. Figurae representationis Methodi T Nominalis sicut infra ostenditur.



t parameter of nominal t method

T-parametri Methodi T Nominalis


Ubi,
IC = Currentus capacitoris = YVC
VC = Voltus capacitoris


  \[ V_S = V_C + I_S \frac{Z}{2} \]



  \[ V_C = V_R + I_R \frac{Z}{2} \]


Ex lege KCL;


  \[ I_S = I_R + I_C \]



  \[ I_S = I_R + Y V_C \]



  \[ I_S = I_R + Y (V_R + I_R \frac{Z}{2}) \]



  \[ I_S = I_R + Y V_R + Y I_R \frac{Z}{2}) \]



(7) \begin{equation*} I_S = Y V_R + I_R (1 + \frac{YZ}{2}) \end{equation*}


Nunc,


  \[ V_S = V_R + I_R \frac{Z}{2} + I_S \frac{Z}{2} \]



  \[ V_S = V_R + I_R \frac{Z}{2} + \frac{Z}{2} \left[ YV_R + I_R (1 + \frac{YZ}{2}) \right] \]



  \[ V_S = V_R + I_R \frac{Z}{2} + \frac{Z}{2} YV_R + \frac{Z}{2} I_R (1 + \frac{YZ}{2}) \]



(8) \begin{equation*} V_S = V_R \left( 1 + \frac{YZ}{2} \right) + I_R \left( Z + \frac{YZ^2}{4} \right) \end{equation*}


Nunc, comparare aequationes-7 et 8 cum aequationibus parametri T et obtinemus,


  \[ A = 1 + \frac{YZ}{2} \]



  \[ B = Z(1+\frac{YZ}{4}) \]



  \[ C = Y \]



  \[ D = 1 + \frac{YZ}{2} \]


Methodus Nominalis π

In hac methodo, capacitas lineae transmissionis in duas partes dividitur. Una pars ponitur ad extremum mittendi, altera pars ad extremum accipiendi. Figura graphica huius methodi nominalis π ut sequitur ostenditur.



t parameter of nominal pi method

T-parametri Methodi Nominalis π



  \[ I_S = I_1 + I_{C2} \]



  \[ I_1 = I_R + I_{C1} \]



  \[ I_{C1} = \frac{Y}{2} V_R \; and \; I_{C2} = \frac{Y}{2} V_S \]


Ex figura superior, possumus scribere;


  \[ V_S = V_R + I_1 Z \]



  \[ V_S = V_R + (I_R + I_{C1}) Z \]



  \[ V_S = V_R + Z (I_R + \frac{Y}{2} V_R) \]



  \[ V_S = V_R + Z I_R + Z \frac{Y}{2} V_R \]



(9) \begin{equation*} V_S = V_R \left(1 + \frac{YZ}{2} \right) + Z I_R \end{equation*}


Nunc


  \[ I_S = I_1 + I_{C2} \]



  \[ I_S = (I_R + I_{C1}) + I_{C2} \]



  \[ I_S = I_R + \frac{Y}{2} V_R + \frac{Y}{2} V_S \]


Pone valorem VS in hanc aequationem,


  \[ I_S = I_R + \frac{Y}{2} V_R + \frac{Y}{2} \left[ V_R \left(1 + \frac{YZ}{2} \right) + Z I_R \right] \]



  \[ I_S = I_R + \frac{Y}{2} V_R + \frac{Y}{2} (1 + \frac{YZ}{2}) V_R + \frac{Y}{2} I_R Z \]



(10) \begin{equation*} I_S = I_R \left[ 1 + \frac{YZ}{2} \right] + Y V_R \left[ 1 + \frac{YZ}{4} \right] \end{equation*}


Per comparando aequationes-9 et 10 cum aequationibus parametrorum T, habemus;


  \[ A = 1 + \frac{YZ}{2} \]



  \[ B = Z \]



  \[ C = Y \left( 1 + \frac{YZ}{4} \right) \]



  \[ D = 1 + \frac{YZ}{2} \]


Linea Transmissoria Longa

Linea transmissoria longa ut rete distributum modelatur. Non potest ut rete concentratum assumi. Modelus distributus lineae transmissive longae sicut figura subiecta ostenditur.



t parameter of long transmission line

T-parametri linea longa transmissionis


Longitudo lineae est X km. Ut lineam transmissionis analysemus, consideramus partem parvam (dx) lineae. Et sic ut in figura infra demonstratur.



long transmission line t parameter


Zdx = impedimentum seriei
Ydx = impedimentum shunt

Tensio super longitudinem crescens. Ergo, ascensus tensionis est;


  \[ dV = IZdx \]



  \[ \frac{dV}{dx} = IZ \]


Similiter, ampera ab elemento ducta est;


  \[ dI = VYdx \]



  \[ \frac{dI}{dx} = VY \]


Differentiando aequationes supras;


  \[ \frac{d^2V}{dx^2} = Z \frac{dI}{dx} = ZVY \]


Solutio generalis aequationis supradictae est;


  \[ V = K_1 cosh(x\sqrt{YZ}) + K_2 sinh(x \sqrt{YZ}) \]


Nunc, differentia hanc aequationem respectu X,


  \[ \frac{dv}{dx} = K_1 \sqrt{YZ} sinh(x\sqrt{YZ}) + K_2 \sqrt{YZ} cosh(x\sqrt{YZ}) \]



  \[ IZ = K_1 \sqrt{YZ} sinh(x\sqrt{YZ}) + K_2 \sqrt{YZ} cosh(x\sqrt{YZ}) \]



  \[ I = \sqrt{\frac{Y}{Z}} \left[ K_1 sinh(x\sqrt{YZ}) + K_2 cosh(x\sqrt{YZ}) \]


Nunc, oportet nos constantes K1 et K2 invenire;

Pro hac re assumamus;


  \[ x=0, \; V=V_R, \; I=I_R \]


Ponendo haec valores in aequationibus supra;


  \[ V_R = K_1 cosh 0 + K_2 sinh 0 \]



  \[ V_R = K_1 + 0 \]



  \[ K_1 = V_R \]



  \[ I_R = \sqrt{\frac{Y}{Z}} \left[ K_1 sinh 0 + K_2 cosh 0 \right] \]



  \[ I_R = \sqrt{\frac{Y}{Z}} [0+K_2] \]



  \[ K_2 = \sqrt{\frac{Z}{Y}} \]


Itaque,


  \[ V_S = V_R cosh (x\sqrt{YZ}) + \sqrt{\frac{Z}{Y}} I_R sinh (x\sqrt{YZ}) \]



  \[ I_S = \sqrt{\frac{Y}{Z}} V_R sinh (x\sqrt{YZ}) + I_R cosh (x\sqrt{YZ}) \]



  \[Z_C = \sqrt{\frac{Z}{Y}} \, and \, \gamma = \sqrt{YZ} \]


Ubi,

ZC = Impedentia Characteristica
ɣ = Constantia Propagationis


  \[ V_S = V_R cosh \gamma x + I_R Z_C sinh \gamma x \]



  \[ I_S = \frac{V_R}{Z_C} sinh \gamma x + I_R cosh \gamma x \]


Compare haec aequationes cum aequationibus T-parametrorum;


  \[A=cosh \gamma x\]



  \[B=Z_C sinh \gamma x \]



  \[C=\frac{sinh \gamma x}{Z_C} \]



  \[D=\cos \gamma x \]


Conversio parametrorum T ad alios parametros

Alia possumus invenire ex aequationibus parametrorum T. Ad hoc, necesse est invenire coniunctam aequationum aliorum parametrorum in terminis parametrorum T.

Considera rete biportale generalizatum ut infra figura ostenditur.


conversion of t parameters to other parameters


In hac figura, directio currentis receptivi mutatur. Itaque, consideramus paucas mutationes in aequationibus parametrorum T.


  \[ V_S = V_1, \; V_R = V_2, \; I_S = I_1, \; I_R = -I_2, \]


Aequationes T parametrorum sunt


(11) \begin{equation*} V_1 = AV_2 - BI_2 \end{equation*}



(12) \begin{equation*} I_1 = CV_2 - DI_2 \end{equation*}


Parametri T ad parametri Z

Sequens set aequationum representat parametros Z.


(13) \begin{equation*} V_1 = Z_{11}I_1 + Z_{12}I_2 \end{equation*}



(14) \begin{equation*} V_2 = Z_{21}I_1 + Z_{22}I_2 \end{equation*}


Nunc, inveniemus aequationes parametrorum Z in terminis parametrorum T.


  \[ CV_2 = I_1 + DI_2 \]



(15) \begin{equation*} V_2 = \frac{1}{C}I_1 + \frac{D}{C} I_2 \end{equation*}


Nunc comparate aequationem-14 cum aequatione-15


  \[Z_{21} = \frac{1}{C}, \quad Z_{22} = \frac{D}{C} \]


Nunc


  \[ V_1 = A \left[ \frac{1}{C} I_1 + \frac{D}{C}I_2 \right] - BI_2 \]



  \[ V_1 = \frac{A}{C} I_1 + \frac{AD}{C}I_2 - BI_2 \]



(16) \begin{equation*} V_1 = \frac{A}{C}I_1 + \left( \frac{AD-BC}{C} \right) I_2 \end{equation*}


Comparatio aequationis (13) cum aequatione (16);


  \[Z_{11} = \frac{A}{C}, \quad Z_{12} = \frac{AD-BC}{C} \]


Parametri T ad parametri Y

Coniunctio aequationum parametrorum Y est;


(17) \begin{equation*} I_1 = Y_{11}V_1 + Y_{12}V_2 \end{equation*}



(18) \begin{equation*} I_2 = Y_{21}V_1 + Y_{22}V_2 \end{equation*}


Ex aequatione duodecima;


  \[DI_2 = CV_2 - I_1 \]



  \[ I_2 = \frac{C}{D}V_2 - \frac{1}{D}I_1 \]


Pone hanc valorem in aequatione-11;


  \[ V_1 = AV_2 - B \left[ \frac{C}{D}V_2 - \frac{1}{D}I_1 \right] \]



  \[ V_1 = AV_2 -\frac{BC}{D}V_2 + \frac{B}{D}I_1 \]



  \[ V_1 = V_2 \left[ \frac{AD-BC}{D} \right] +\frac{B}{D}I_1 \]



  \[ \frac{B}{D}I_1 = V_1 - V_2 \left[ \frac{AD-BC}{D} \right] \]



(19) \begin{equation*} I_1 = \frac{D}{B}V_1 - \frac{BC-AD}{B}V_2 \end{equation*}


Compare hanc aequationem cum aequatione-17;


  \[Y_{11} = \frac{D}{B}, \quad Y_{12} = \frac{BC-AD}{B} \]


Ex aequatione 11;


  \[BI_2 = AV_2 - V_1 \]



(20) \begin{equation*} I_2 = \frac{A}{B} V_2 - \frac{1}{B}V_1 \end{equation*}


Compara hanc aequationem cum aequatione 18;


  \[ Y_{21} = \frac{-1}{B}, \quad Y_{22} = \frac{A}{B} \]


Parametri T ad parametri H

Coniunctio aequationum parametrorum H est;


(21) \begin{equation*} V_1 = H_{11}I_1 + H_{12}V_2 \end{equation*}



(22) \begin{equation*} I_2 = H_{21}I_1 + H_{22}V_2 \end{equation*}


Ex aequatione 12;


  \[ DI_2 = CV_2 - I_1 \]



(23) \begin{equation*} I_2 = \frac{C}{D} V_2 - \frac{1}{D}I_1 \end{equation*}


Comparatio huius aequationis cum aequatione-22;


  \[H_{21} = \frac{-1}{D}, \quad H_{22} = \frac{C}{D} \]



  \[ V_1 = AV_2 - B \left[ \frac{C}{D} V_2 - \frac{1}{D}I_1 \right] \]



  \[ V_1 = AV_2 - \frac{BC}{D}V_2 + \frac{B}{D}I_1 \]



(24) \begin{equation*} V_1 = V_2 \left[ \frac{AD-BC}{D} \right] +  \frac{B}{D}I_1 \end{equation*}



  \[ H_{11} = \frac{B}{D}, \quad H_{12} = \frac{AD-BC}{D} \]

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