ÇUKUROVA UNIVERSITY INSTITUTE OF NATURAL AND APPLIED ...

4. MODELING OF PROPOSED DVR Mustafa İNCİ
Figure 4.17. Conventional phase freezer unit(Köroğlu,2012)
The most important disadvantage of the conventional phase freezer unit is
that it tracks both supply and load voltages and needs two independent voltage
measurements. The conventional method works with no error in simulation
environment but in practical it is very difficult to measure both supply and load side
voltages. Supply measurement should be somewhere upstream of the fault which is
difficult to locate and measure. To overcome the disadvantages of the conventional
phase freezer unit, proposed algorithm is used in this thesis seen from Figure
4.20(Köroğlu,2012).
The block diagram of the proposed DVR control system for single-phase is
shown in Figure 4.19. Supply-side and load-side voltages are defined by (4.47) and
(4.48), respectively
v
presag
presag
( ω t + ϑ )
= V × cos (4.47)
presag
v
l
sl
( ω t + ϑ )
= V × cos (4.48)
l
Based on the presag compensation method, the voltage phasor, which must be
injected by the DVR, is the complex difference between the supply voltage phasor
and the presag supply voltage phasor, as shown in the vector diagram of Figure 4.17.
This phasor ( V
inj
) is calculated by the phasor subtraction unit, shown in Figure 4.18,
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