Hi guys,
I'm facing with the following problem. I would like to define the right function for controlling line currents below dedicated values (e.g. 60 A per line). I've started with solve equation and Kirchoff's first law, however it doesn't work as I expected. Does anybody have a sollution how to cope with this problem? The known values are limited line currents (i.e. 60 Aef), limited active powers of every load (P1 - P5) and phase-2-phase voltages (i.e. 230 Vef).
The problem is that I don't know how to easy transform active powers (variables limited to 230V*32A = 7360 W) and known phase-2-phase voltages (230*sqrt(2)<0°, 230*sqrt(2)<120° and 230*sqrt(2)<240°) to phase-2-phase currents (x1 - x5)? By this the system would get 5 more equations and might be solvable.
So far I don't get any useful result, only the warning "Unable to find explicit solution For options, see help. ..."
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clc;clear all;
syms Y1 Y2 Y3 y1 y2 y3 x1 x2 x3 x4 x5
assume(Y1 >= 0);
assume(Y2 >= 0);
assume(Y3 >= 0);
assume(Y1 <= 60*sqrt(2));
assume(Y2 <= 60*sqrt(2));
assume(Y3 <= 60*sqrt(2));
assume(abs(x1) <= 32*sqrt(2));
assume(abs(x2) <= 32*sqrt(2));
assume(abs(x3) <= 32*sqrt(2));
assume(abs(x4) <= 32*sqrt(2));
assume(abs(x5) <= 32*sqrt(2));
assume(abs(x1) >= 0);
assume(abs(x2) >= 0);
assume(abs(x3) >= 0);
assume(abs(x4) >= 0);
assume(abs(x5) >= 0);
y1 = Y1*cos(0) + 1i*Y1*sin(0);
y2= Y2*cos(120*(pi/180))+1i*Y2*sin(120*(pi/180));
y3 = Y3*cos(240*(pi/180))+1i*Y3*sin(240*(pi/180));
y1 = x1 + x3;
y2 = -x1 - x2 - x4 - x5;
y3 = x2 + x4 + x5 - x3;
sol = solve([y1,y2,y3],[x1,x2,x3,x4,x5],'ReturnConditions',true);
sol1=sol.x1
sol2=sol.x2
sol3=sol.x3
sol4=sol.x4
sol5=sol.x5
sol.conditions;
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