Page 140 - Decision Making Applications in Modern Power Systems

Power quality issues of smart microgrids Chapter | 4 105

I Ind I DG I MG I Grid

I Local
V PCC
DG Grid
V DG

Harmonic-free
I Grid
I MG V PCC PCC voltage
I DG
Harmonic-free
local load current
I DG I MG V PCC I Grid

Harmonic-free
I DG I MG V PCC I Grid DG current

FIGURE 4.6 Overall view of harmonic compensation in microgrids.

V PCC I ref_f
PLL and
synchronization
K p
I DG
2K ω b s
G (s) = if
V PCC R s 2 + 2ω b s + () f ω 2
V PCC Comp H D (S) –1/R v
Harmonic extraction (s) = Σ 2K ω
ih b s
I Local I ref_h G
I Local-Load H D (S) H 3,5,7,9,11 s 2 + 2ω b s + (hω ) 2
Comp h= f
Harmonic extraction
I DG Comp
*
0 G inner s = V Out
() K inner
I ind
FIGURE 4.7 Overall view of CCM with harmonic current reference calculation. CCM,
Current-controlled method.
reference calculation methods. To have a harmonic-free output current of
MFDG, it is the default compensating objective of CCM, that is, it is simply
done by setting the harmonic current reference to zero as in (4.2).
I ref 5 I ref f 1 I ref h ð4:1Þ
f is the fundamental
where I ref is the main current reference for CCM, I ref
h is the harmonic reference current for CCM.
current reference, and I ref
I ref 5 I ref f ð4:2Þ
To compensate the local load harmonic current, as it could be seen in
(4.3), the harmonic reference would be the harmonic elements of the local