“Controlled DC-Voltage Power Port” Controlled in a dq-Frame
Synchronized to the Voltage V
s,abc
Introduction:
In this assignment we are repeating the simulation of the Example 8.4 from the text book, Voltage Sourced
Converters in Power Systems [2]. We are using VSC (Voltage Source Converter) from assignment-2 and
PLL (Phased-Locked Loop) from assignment-3. In many applications, for example, photovoltaic (PV)
systems and fuel-cell systems, the VSC DC side is not interfaced with a voltage source; rather, it is
connected to a (DC) power source that needs to be interfaced and exchange (real) power with the AC
system [2]. Thus, the DC-bus voltage is not imposed and, therefore, needs to be regulated [2]. Therefore,
the source in VSC from assignment-2 will be a dependent current source such that its current, i
ext
, equals
the value P
ext
/v
dc.
PWM modulator used in this assignment (and Example 8.4 from the textbook) is a third-
harmonic injected PWM as a means for extending the VSC permissible voltage range. Because we are
using the third-harmonic injected PWM, the VSC AC-side terminal voltage can reach up to ±1.15 (V
DC
/2),
instead of ±(V
DC
/2) under the conventional PWM [2]. Also, the stepwise changes in V
DCref,,
P
ext
and Q
sref
are different than the Example 8.4 from the textbook.
Given Parameters:
V
sd
= 391 V, ω
0
= 377 rad/s
C = 9625 µF, L = 100 µH
R = 0.75 mΩ, r
on
= 0.88 mΩ
V
d
= 1.0 V, f
s
= 1680 Hz
