how can I simulate distance relay to protect HVDC transmission line and distance relay m.file code in MATLAB

How can I plot R-X diagram of distance relay characteristics with Zone specifications,i.e specifying Zone1, Zone2 and zone 3 ?

Please anyone guide me how do I model the distance/impedance relay by MATLAB M-file? or Can anyone share MATLAB code (in M-file) for distance/impedance relay

Answer 1

[Vaibhav]

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!