%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
% synphas.m - plots phasors for a synchronous generator and
%             equivalent grid prior to synchronization to
%             assess voltage across contactors to be closed.
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
clear;
fdiff=input(' Frequency difference small?( Y or N )  ','s');
mdiff=input(' Voltage magnitude different?( Y or N )  ','s');
pdiff=input(' Phase sequence different?( Y or N )  ','s');
if fdiff == 'Y'; n=100; else; n=15; end; % Set angle increment
if mdiff == 'Y'; m=0.5; else; m=1; end   % Set magnitudes
if pdiff == 'Y'; k=-1; else; k=1; end    % Set phase sequence
% 123. - Grid, abc* - oncoming alternator
theta=linspace(0,2*pi,n);A1=0; A2=-2*pi/3; A3=2*pi/3;
for i=1:n; pause(0.0001)
Aa=theta(i); Ab=Aa-k*2*pi/3; Ac=Aa+k*2*pi/3;
polar(0,1.25); hold on 

% Configurable phasors of the alternator - asterisks at the tip
polar([0 Aa],[0 m],'r');   polar(Aa,m,'*'); % Red
polar([0 Ab],[0 m],'y-.'); polar(Ab,m,'*'); % Yellow
polar([0 Ac],[0 m],'b--'); polar(Ac,m,'*'); % Blue

% Fixed phasors of the grid - dots at the tip
polar([0 A1],[0 1],'r');   polar(A1,1,'.'); % Red
polar([0 A2],[0 1],'y-.'); polar(A2,1,'.'); % Yellow
polar([0 A3],[0 1],'b--'); polar(A3,1,'.'); % Blue 

% Contactor voltages indicated by dotted green lines
polar([A1 Aa],[1 m],'g:'); polar([A2 Ab],[1 m],'g:');
polar([A3 Ac],[1 m],'g:'); hold off
end
text(1.1,0.1,'V1'); text(-0.7,-1,'V2'); text(-0.7,1,'V3');
name=['Phasor diagrams for synchronizing alternator';
   '                                            ';
   '                                            ']; title(name);