regulating mid point voltage of a transmission line using shunt compensation

%program for short lines
clear;
clc;

%continue with the program vl = input('enter line load voltage: '); f = input('enter local frequency: '); l = input('enter line constant in H/KM: '); length = input('enter length of line: '); r = input('enter the resistive constant: '); power = input('enter the load power: '); pf = input('enter load power factor: ');

%evaluate the parameters xl=l*length*pi*2*f; p=power/3;

res=r*length; z=complex(res,xl); A=1; B=z; C=0; D=1; vlo=vl/sqrt(3); %evaluate the load current ilmag=p/(vlo*pf); %assuming a lagging power factor il=complex(ilmag*cos(acos(pf)),-ilmag*sin(acos(pf))); vload=complex(vlo,0);

%evaluate the value of Vsending end and Isending end

vs=A*vload + B*il; is=C*vload + D*il; %calculte sending end power s=conj(is)*vs; %calculate voltage regulation vr=((abs(vs)-abs(vlo))/abs(vlo))*100;

%calculate efficiency pin=real(s); pout=p; n=(pout/pin)*100; %evaluating the power factor theta=atan(imag(s)/ real(s)); pfactor=cos(theta);

fprintf ('VS='); disp(vs);

fprintf('IS='); disp(is);

fprintf('power factor at sending end='); disp(pfactor);

fprintf('sending end complex power='); disp(s);

fprintf('voltage regulation='); disp(vr);

fprintf('effiency='); disp(n); %evaluate the per unit values of the line parameters %choosing the base values as follows vbase=vlo;

sbase=p/pf;

zbase=mpower(vbase,2)/sbase;

ibase=sbase/vbase;

zpu=z/zbase;

vreceivingpu=vload/vbase;

ireceivingpu=il/ibase;

vsendingpu=vs/vbase;

isendingpu=is/ibase;

ssendingpu=s/sbase;

precevingpu=p/sbase;

fprintf('the per unit value of the impedance='); disp(zpu); fprintf('the per unit value of the receiving end voltage='); disp(vreceivingpu); fprintf('the per unit value of the receiving end current='); disp(ireceivingpu); fprintf('the per unit value of the sending end voltage='); disp(vsendingpu); fprintf('the per unit value of the sending end current='); disp(isendingpu); fprintf('the per unit value of the sending end apparent power='); disp(ssendingpu); fprintf('the per unit value of the receiving end real power='); disp(precevingpu);

%for power factor correction

thetanew=acos(pfdesired);

qold=imag(s);

qnew=real(s)*tan(thetanew); %evaluating the value of the capacitor bank

qc=qold-qnew; pfdesired = input('enter the desired power factor: '); c=qc/(mpower(abs(vs),2)*2*pi*f);

fprintf('value of the capacitor bank in farads='); disp(c); fprintf('the reactive power to be supplied by the capacitane bank in var='); disp(qc);

[Joel Van Sickel]

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