Add power analyser code

Signed-off-by: Warrick Lo <warrick.s.z.lo@gmail.com>

1 files changed, 57 insertions, 0 deletions

diff --git a/matlab/poweran.m b/matlab/poweran.m
new file mode 100644
index 0000000..e5f00df
--- /dev/null
+++ b/matlab/poweran.m
@@ -0,0 +1,57 @@
+function poweran(filename, pf_angle)
+	% Power analyser
+	%
+	% Analyse and plot the instantaneous, real, and reactive
+	% power of a waveform given by a tab-separated value
+	% (TSV) file.
+	%
+	% Required measurements to input:
+	% power factor angle (degree)
+	%
+	% The following column headers for the TSV are assumed:
+	% time, v1, v2, v3, i1, i2, i3
+	%
+	% Time measurements are assumed to be in milliseconds.
+	% All voltages and currents are assumed to be given
+	% in Volts and Amperes, respectively.
+
+	data = readtable(filename, FileType="text", Delimiter="\t");
+
+	L = length(data.time);
+
+	t = linspace(0, data.time(end), L);
+	p = data.v1(1:L) .* data.i1(1:L);
+
+	% Sum over a full period to get the RMS values.
+	n = length(data.time(data.time < 1e3/60));
+	vrms = sqrt(sum(data.v1(data.time < 1e3/60).^2)/n);
+	irms = sqrt(sum(data.i1(data.time < 1e3/60).^2)/n);
+
+	% These are constant in time so we extrapolate with two points
+	% to save compute time.
+	real_power = ones(2) * vrms * irms * cos(deg2rad(pf_angle));
+	reactive_power = ones(2) * vrms * irms * sin(deg2rad(pf_angle));
+
+	display(vrms);
+	display(irms);
+
+	figure(1);
+
+	subplot(3, 1, 1);
+	plot(t, p, "r", LineWidth=2);
+	title("Instantaneous Power versus Time");
+	xlabel("Time, $t$ (ms)", Interpreter="latex");
+	ylabel("Power, $p(t)$ (W)", Interpreter="latex");
+
+	subplot(3, 1, 2);
+	plot([0 data.time(end)], real_power, "g", LineWidth=2);
+	title("Real Power versus Time");
+	xlabel("Time, $t$ (ms)", Interpreter="latex");
+	ylabel("Real Power, $P$ (W)", Interpreter="latex");
+
+	subplot(3, 1, 3);
+	plot([0 data.time(end)], reactive_power, "b", LineWidth=2);
+	title("Reactive Power versus Time");
+	xlabel("Time, $t$ (ms)", Interpreter="latex");
+	ylabel("Reactive Power, $Q$ (VAR)", Interpreter="latex");
+end
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