ÇUKUROVA UNIVERSITY INSTITUTE OF NATURAL AND APPLIED ...

3. FUNDAMENTALS OF DVR Mustafa İNCİ
The basic principle behind the design of the filter is to provide a shunt path
for the harmonic current and a series impedance to carry the harmonic voltages. To
achieve this goal, the capacitor should be chosen to satisfy (Choi, et al., 2002):
Z = K Z , K >> 1
(3.13)
Load ( m)
f Cf ( m)
f
Where Z − j ( m C)
(
>> / ω andω 0
= 2πf
0,
f0
, represents the fundamental
cf m)
0
frequency, and
is the order of the lowest harmonics to be attenuated. From Figure
3.10, let V
inv(n)
and V
L(n)
represent the respective nth order harmonic voltages on the
inverter and load-side of the L-C filter and n=m,m+1,m+2,m+,,,,,M. M is the order of
the highest harmonics to be attenuated. By using (3.13), we can obtain the following
relationship:
V = K V
(3.14)
load ( n)
( n)
inv(
n)
2
Where = 1/ ( n ) LC 1)
K n
ω . Thus,
( )
0
−
1
1+
K(
n)
L = (3.15)
2
( nω
) C
0
From (3.13), it is obvious that for a given
Z
load
, C is directly proportional to
K
f
. Thus, a suitable value for C can be obtained by the selection of an appropriate
value for K . Furthermore, (3.14) means that, in order to reduce the nth order
f
harmonic voltage with rms value from V
inv(n)
to V
load (n)
, the inductor of the filter can
be chosen according to (3.15) once the capacitor value C is given and K
(n)
is chosen
according to (3.14). Indeed, it will be shown in the next section that the voltage
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