5.7\" Write a MATLAB function named [ABCD] = abcdm(z, y, Lng) to evaluate and re

Question

5.7" Write a MATLAB function named [ABCD] = abcdm(z, y, Lng) to evaluate and return the ABCD transmission matrix for a medium-length transmis- sion line where z is the per phase series impedance per unit length, y is the shunt admittance per unit length, and Lngt is the line length. Then, write a program that uses the above function and çomputes the receiving end quan- tities, voltage regulation, and the line efficiency when sending end quantities are specified. The program should prompt for the following quantities: The sending end line-to-line voltage magnitude in kV The sending end voltage phase angle in degrees

Explanation / Answer

z=input('Line series impedance per phase per unit length z=');
y=input('Line shunt admittance per phase per unit length y=');
Lngt = input('Transmission line length = ');
ABCD = abcdm(z, y,Lngt)
VL_s=input('Sending end line-to-line voltage magnitude in kV=');
AngV_s=input('Sending end voltage phase angle in degree = ');
P_s =input('Three-phase sending end real power in MW ');
Q_s =input('Three-phase sending end reactive power in Mvar ');
S_s = P_s + j*Q_s; % MVA
AngV_srd = AngV_s*pi/180; % Radian
V_s = VL_s/sqrt(3)*(cos(AngV_srd) + j*sin(AngV_srd)); %kV
I_s = conj(S_s)/(3*conj(V_s)); % kA
IL_s= abs(I_s)*1000; AngI_srd = angle(I_s);
AngI_s = AngI_srd*180/pi;
VI_r = inv(ABCD)*[V_s; I_s];
V_r = VI_r(1); VL_r = sqrt(3)*abs(V_r);
AngV_rrd = angle(V_r); AngV_r = AngV_rrd*180/pi;
I_r = VI_r(2); IL_r = abs(I_r)*1000; AngI_rd = angle(I_r);
AngI_r = AngI_rd*180/pi;
S_r = 3*V_r*conj(I_r); P_r = real(S_r);
Q_r = imag(S_r); A = abs(ABCD(1,1));
Reg = (VL_s/A - VL_r)/VL_r*100;
Eff = P_r/P_s*100;
fprintf('Sending end line-to-line voltage =%g KV ', VL_s)
fprintf('Sending end voltage phase angle =%g Degree ',AngV_s)
fprintf('Sending end real power = %g MW ', P_s)
fprintf('Sending end reactive Power = %g Mvar ', Q_s)
fprintf('Sending end current = %g A ', IL_s)
fprintf('Sending end current phase angle=%g Degree ',AngI_s)
fprintf('receiving end line-to-line voltage = %g KV ',VL_r)
fprintf('receiving end voltage phase angle=%g Degree ',AngV_r)
fprintf('receiving end real power = %g MW ', P_r)
fprintf('receiving end reactive Power = %g Mvar ', Q_r)
fprintf('receiving end current = %g A ', IL_r)
fprintf('receiving end current phase angle=%g Degree ',AngI_r)
fprintf('Voltage regulation = %g percent ',Reg)
fprintf('Transmission efficiency = %g percent ',Eff)
typing ch5p7 at the MATLAB prompt result in
Line series impedance per phase per unit length z = 0.03+j*0.4
Line shunt admittance per phase per unit length y = j*4.0e-6
Transmission line length = 125
ABCD =
0.9875+ 0.0009i 3.7500+50.0000i
0.0000+ 0.0005i 0.9875+ 0.0009i
Sending end line-to-line voltage magnitude in kV = 350
Sending end voltage phase angle in degree = 0
Three-phase sending end real power in MW 407
Three-phase sending end reactive power in Mvar 7.883
Sending end line-to-line voltage = 350 kV
Sending end voltage phase angle = 0 Degree
Sending end real power = 407 MW
Sending end reactive Power = 7.883 Mvar
Sending end current = 671.502 A
Sending end current phase angle = -1.1096 Degree
Receiving end line-to-line voltage = 345.003 kV
Receiving end voltage phase angle = -9.63278 Degree
Receiving end real power = 401.884 MW
Receiving end reactive Power = 0.0475969 Mvar
Receiving end current = 672.539 A
Receiving end current phase angle = -9.63957 Degree
Voltage regulation = 2.73265 percent
Transmission efficiency = 98.7429 percent

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