Hi Ahmed
You can refer to the below example to plot an R-X (Resistance-Reactive) diagram for a distance relay with Zone 1, Zone 2, and Zone 3 specifications.
% Define the zone reach as a percentage of the line impedance
zone1_reach = 1.0; % 100% reach of the line impedance
zone2_reach = 1.5; % 150% reach
zone3_reach = 2.0; % 200% reach
% Define the impedance of the line
Z_line = 1 + 1j; % Example line impedance
% Calculate the impedance values for each zone
Z1 = Z_line * zone1_reach;
Z2 = Z_line * zone2_reach;
Z3 = Z_line * zone3_reach;
% Define the radius for each zone
R1 = real(Z1);
X1 = imag(Z1);
R2 = real(Z2);
X2 = imag(Z2);
R3 = real(Z3);
X3 = imag(Z3);
% Define the angles for plotting the circles
theta = linspace(0, 2*pi, 100);
% Calculate the x and y coordinates for each zone circle
x1 = R1 * cos(theta);
y1 = X1 * sin(theta);
x2 = R2 * cos(theta);
y2 = X2 * sin(theta);
x3 = R3 * cos(theta);
y3 = X3 * sin(theta);
% Plot the circles for each zone
figure;
hold on;
plot(x1, y1, 'r', 'LineWidth', 2); % Zone 1 in red
plot(x2, y2, 'g', 'LineWidth', 2); % Zone 2 in green
plot(x3, y3, 'b', 'LineWidth', 2); % Zone 3 in blue
% Plot the origin
plot(0, 0, 'ko', 'MarkerFaceColor', 'k');
% Set the axis labels and title
xlabel('Resistance (R)');
ylabel('Reactance (X)');
title('R-X Diagram of Distance Relay Characteristics');
legend('Zone 1', 'Zone 2', 'Zone 3');
% Set the axis limits and grid
axis equal;
grid on;
hold off;
This script plots an R-X diagram showing three distance relay zones as circles centered at the origin. Each circle’s radius corresponds to the impedance reach of the relay:
- Zone 1: Red circle (100% of line impedance)
- Zone 2: Green circle (150% of line impedance)
- Zone 3: Blue circle (200% of line impedance)
Hope this gets you started!
