MatlabSimulink 3 phase pisection model of transmission lines (impedance calculatio)
I am using the "ThreePhase PI Section Line" MatlabSimulink block from Simpowersystems blockset for modelling an electric power system transmission line.
I had obtained the data from a research paper regarding the transmission line specifications (provided as sequence values).
Since I am trying to do actual impedance calculations of each phase for distance protection & fault location purposes, I tried to compute the variation of per phase impedance using a program (given below).
The distance is multiplied to the data to get the actual values.
The impedances are computed, the sequence impedances and the per phase impedances are found out. The values of resistance and reactance are computed from the real part and imaginary part respectively. This operation is done for various distances and the plot shows that.
I find that the values plot rise to very high values (order of 1e200). How can current flow if impedance is so high ? If the system data is inappropriate, please tell me why.
Please suggest the reason for such a problem and how can I overcome it?
Thanks in advance ðŸ˜€
I had obtained the data from a research paper regarding the transmission line specifications (provided as sequence values).
Since I am trying to do actual impedance calculations of each phase for distance protection & fault location purposes, I tried to compute the variation of per phase impedance using a program (given below).
clear all; clc;close all; a=exp(deg2rad(120)*1j); %% a = 0.5000 + 0.8660j A = [1 1 1; 1 a^2 a; 1 a a^2]; %% Matrix for Symmetrical component transformation Fo = 60; %% Line Specification using sequence values (taken from paper) R10 = [0.0317 0.3192]; L10 = [0.3204 1.0083]./(2*pi*60) ; C10 = [10.838e9 7.6493e9]; Distance = 1:150; %% in km for k = 1:length(Distance) R10 = R10*Distance(k); L10 = L10*Distance(k); C10 = C10*Distance(k); XL10 = (2*pi*Fo)*L10; XC10 = 1./((2*pi*Fo)*C10); Z10 = R10 + 1j*( XL10  XC10 ); Z0(k) = Z10(2); Z1(k) = Z10(1); Z2(k) = Z1(k); Z012 = [Z0(k) 0 0; 0 Z1(k) 0; 0 0 Z2(k)]; Zabc = A*Z012*((1/3)*(A')); Zs(k) = Zabc(1); Zm(k) = Zabc(2); end figure(1);subplot(2,1,1);plot(Distance,real(Z0));subplot(2,1,2);plot(Distance,imag(Z0)); figure(2);subplot(2,1,1);plot(Distance,real(Z1));subplot(2,1,2);plot(Distance,imag(Z1)); figure(3);subplot(2,1,1);plot(Distance,real(Zs));subplot(2,1,2);plot(Distance,imag(Zs)); figure(4);subplot(2,1,1);plot(Distance,real(Zm));subplot(2,1,2);plot(Distance,imag(Zm));The program takes the system data of the transmission line (which are given in unit/km), which can be used as parameters for the Simulink 3 phase pisection block.
The distance is multiplied to the data to get the actual values.
The impedances are computed, the sequence impedances and the per phase impedances are found out. The values of resistance and reactance are computed from the real part and imaginary part respectively. This operation is done for various distances and the plot shows that.
I find that the values plot rise to very high values (order of 1e200). How can current flow if impedance is so high ? If the system data is inappropriate, please tell me why.
Please suggest the reason for such a problem and how can I overcome it?
Thanks in advance ðŸ˜€
Replies

steelomaticRe: MatlabSimulink 3 phase pisection model of transmission lines (impedance calcula
not really into power systems
but from wht i remember
admittance and impedance matrix should be seperate
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