Opt-D7 - Danfoss Vacon NXP Applications Manual

14 · vacon
Q2
SG
The normal operation voltage range in a land-based grid is usually between 80% and 115% of the
grid nominal voltage.
The voltage losses compensation is handled separately for Active power (kW) and Reactive power
(kVar), the latter being more significant. The Active power voltage losses are compensated with
Inductor Losses parameter (P2.2.8.6) and Reactive power voltage losses are compensated with
Inductor Size parameter (P2.2.8.5).
Uncompensated system may result in unnecessary reactive power circulation in a grid between the
different power sources and wrong grid voltage.
OPT-D7 can be used to compensate the voltage losses (closed loop voltage compensation) but it is
recommended to do an open loop voltage compensation tuning in case of OPT-D7 failure. When the
OPT-D7 measurements exceed the set limit values, the voltage compensation falls back to open loop
control.
Inductor Size and Losses affect
Grid Nom. Voltage: 400 Vac, Reactive Current: 30%, Active Current 50%, Inductor
Size: 15%, Inductor Losses: 15%, Voltage Correction: 0 Vac.
Reactive Increase:
Active Increase:
Total increase:
See also document: Voltage Compensation Vxxx.pdf.
1.11

OPT-D7

OPTD7 is an AC sinusoidal voltage measurement board. Using this board, the drive measures the
line voltage, the frequency and the voltage angle information.
The drive can compare this information with its output voltage angle when it runs. This feature can
be used to make synchronisations to a grid that is measured. For example, for line synchronisation
purposes you can use APFIFF44 LineSynch II Application. That will work as a smooth starter.
In Micro Grid application this can be used:
- To synchronise to existing external grid while the drive is running to enable bumpless
transfer from a generator operation to a shore powered operation in a ship.
- To control the grid voltage (Voltage losses compensation).
1
~
U2
Filter
U1
=
Figure 9. Voltage compensation
400 Vac×30%×15%=18 Vac
400 VacIncrease:∶or Losses: 15% 400 Vac×50%×15%×15%=4.5 Vac
18 Vac+4.5 Vac =22.5 Vac
D7
U3
UDC
Filter
Tel. +358 (0)201 2121 • Fax: +358 (0)201 2121 205
General
T1
U5
U4
Q3
Q1
T2
U4 = Transf. GC Side
U5 = Transf. Grid Side