BASIC VARIANTS
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5
5.1.1
Control structure
The power control is as presented below when the battery is directly on DC-link.
Figure 19. DC-link power control
Direct to DC can be used on a system where peak power shaving is desired and grid power sources’
power sharing is done mainly through active power drooping. In such system, the power and grid
frequency behave as shown in the picture below.
Figure 20. Behavior of system power and grid frequency
Grid Converter operation:
•
uGrid-operation mode
o Power control possible when operating parallel with other power sources.
•Reference is base current reference (+/-).
•If the device is operating in island mode, the power reference changes the
frequency.
o Grid frequency variations will affect what will be actual power to the grid.
•Operates like a normal generator.
•Power reference is several times faster than a normal diesel generator.
•Frequency drop in a grid will increase Grid Converter power output without power
reference.
- Useful in situations where PMS is not fast enough or is unable to control.
o Upper system needs to give charging and discharging limit to the drive
o Upper system needs to give minimum and maximum voltage limits to the drive (DC-Link
voltage).
U4
U3
D7
C
T2
T1
Q1
U5
Q3
Filter
Source
DC
Grid
Di
s
c
h
a
rg
e
Power
Frequency
Ge
n
e
ra
to
r
M
o
to
ri
n
g
Average
Charge
Summary of Contents for NX6
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