Calculation Of Harmonic Bins - AEMC 8335 User Manual

Calculation of Harmonic Bins

Harmonic bins are calculated by FFT with 16 bit resolution (1024 samples on
4 cycles) without windowing (IEC 1000-4-7). From real and imaginary compo-
nents, each bin ratio is calculated on each phase Vharm[3][51], Uharm[3][51] and
Aharm[3][51] in proportion to the fundamental value and the phase angles Vph[3]
[51], Uph[3][51] and Aph[3][51] between each bin and the fundamental.
This calculation is accomplished using the following principle:
m od
module in %:
ck: amplitude of the component with a frequency of
Fs: sampled signal
co: DC component
k: ordinal number (spectral bin)
Power Quality Analyzer Model 8335
c
= c × 100
k
k
1

c = b +
k k


1
1024
∑
b
=

k
512

with

1
1024
a
=

k
512


1
c
=

0
1024

angle in degree:
2 2
ja = a + b
k k k
k
π

sin
F
×

s
512

s = 0
k π

∑
cos
F
×

s
512

s = 0
1024
∑
F
s
s = 0
ϕ = arctan
k

s
ϕ
+

k


s
+ ϕ

k

k
=
f f
1
k
4


a
   
k
b
 
k
95