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EOS Power Analysis

The SatLab graph below analyzes the power output of an Earth Observation Satellite under maximum solar gain. The script that generated this graph is shown below.

% Demo: EOS satellite
%
% This demo sets up a satellite for earth observation that passes
% over the earth at noon for optimum light conditions
%

removeAll;
clearGraphic();
setSimEpoch(2000,3,21,12,0,0);
addEpoch('equinox',2000,3,21,12,0,0);
addSatellite('EOS Sat',7171,0,98,0,0,0,'equinox');

%earthstation
earth0 = "Frankfurt";
addStation('Frankfurt', I_earth, 10, 50.05, 8.4, 0.1);

dtime      = 100;
alphaleft  = 45 *d2r;
alphatop   = 0 *d2r;
alpharight =-45 *d2r;

setSimTime(0);
setSimStepSize(dtime);
t = 0:dtime:120*dtime;
fleft = rotx(alphaleft) * [ 0
                            0
                           -1 ];

ftop = rotx(alphatop)*    [ 0
                            0
                           -1 ];

fright= rotx(alpharight)* [ 0
                            0
                           -1 ];

z_matrix = 
[   0 26.75 27.25 27.75 28.25 28.75 29.25 29.75 30.25 30.75 31.25
  100 12.39 12.23 12.14 12.14 11.95 10.64 10.51 10.33 10.14  9.94
   90 12.67 12.59 12.50 12.39 12.26 11.76 11.68 11.36 11.48 11.36
   80 12.77 12.73 12.68 12.63 12.57 12.31 12.27 12.22 12.17 12.11
   70 12.78 12.76 12.74 12.71 12.68 12.55 12.53 12.51 12.48 12.45
   60 12.74 12.73 12.72 12.71 12.69 12.63 12.62 12.61 12.60 12.68
   50 12.68 12.68 12.67 12.67 12.66 12.63 12.63 12.62 12.62 12.91
   40 12.61 12.61 12.61 12.61 12.60 12.59 12.59 12.79 12.88 13.18
   30 12.53 12.53 12.53 12.53 12.53 12.53 12.57 12.63 12.73 12.72
   20 12.46 12.45 12.45 12.45 12.45 12.45 12.45 12.45 12.65 12.45
   10 12.38 12.38 12.38 12.38 12.38 12.38 12.38 12.38 12.58 12.38
    0 12.30 12.30 12.30 12.30 12.30 12.30 12.30 12.30 12.40 12.30
  -10 12.22 12.22 12.22 12.22 12.22 12.22 12.22 12.22 12.22 12.22
  -20 12.14 12.14 12.14 12.14 12.14 12.14 12.14 12.14 12.14 12.14
  -30 12.06 12.06 12.06 12.06 12.06 12.06 12.06 12.06 12.06 12.06
  -40 11.98 11.98 11.98 11.98 11.98 11.98 11.98 11.98 11.98 11.98
  -50 11.70 11.84 11.90 11.90 11.90 11.90 11.90 11.90 11.90 11.90
  -60 11.32 11.62 11.72 11.82 11.82 11.82 11.82 11.82 11.82 11.82
  -70 11.14 11.24 11.44 11.64 11.74 11.74 11.74 11.74 11.74 11.74
  -80 10.95 10.95 11.35 11.45 11.65 11.65 11.65 11.65 11.65 11.65 ];

j            = 0;
temptop      = 0;
templeft     = 0;
tempright    = 0;
solarflux    = 1420;

alpha        = 0.65;
epsilon      = 0.81;
albedo       = 0.3;
sigma        = 5.67e-8;
capacity     = 660;

qir          = 0;
strings_top  = 4;
strings_side = 10;
eview        = 0.045;
dt           = 60;

dtc          = dt/capacity;
reference_flux_si = 1353;
voltage      = 28;
current      = zeros(size(t));

for i=t,j=j+1;
    stepSim;
    [d,r,a,e,v] = PlanetPosition();
    theta = ftop` * unitvector(a(2),e(2));
    theta = max(0,theta);
    temptop = temptop+((theta*solarflux*alpha)
                      -(epsilon*(temptop^4)*sigma))*(dtc);
    current_top = ((strings_top*theta)
                   *table(z_matrix,(temptop-273.15),voltage)
                   *((solarflux/reference_flux_si)/12));

    theta = fleft` * unitvector(a(2),e(2));
    theta = max(0,theta);
    templeft = (templeft+
               ((((theta*solarflux*alpha)+
                  (theta*solarflux*albedo*alpha*eview))
                -(epsilon*(templeft^4)*sigma)
                +theta*qir)*(dtc)));

    current_left = ((strings_side*theta)*
    table(z_matrix,(templeft-273.15),voltage)
        *((solarflux/reference_flux_si)/12));

    theta = fright` * unitvector(a(2),e(2));
    theta = max(0,theta);
    tempright= (tempright+
               ((((theta*solarflux*alpha)+
                  (theta*solarflux*albedo*alpha*eview))
                -(epsilon*(tempright^4)*sigma)+theta*qir)*(dtc)));

    current_right = ((strings_side*theta)
                    *table(z_matrix,(tempright-273.15),voltage)
                    *((solarflux/reference_flux_si)/12));

    current(j)=current_top+current_left+current_right;
endfor

average=sum(current*voltage)/prod(size(t));
erase

window('111');
plot(t,current*voltage,
     t,ones(size(t))*average, 'grid');
title('Power of EOS Satellite')
ylabel('P [Watt]');
xlabel('t [sec]')
wtext(2000,average+10,'Average Power');