Siemens SIMADYN D Manual page 451

6QG2
Line voltage check
Line supply
quantities
Pulse
synchronization
System- and communication configuring D7-SYS - SIMADYN D
Edition 06.2002
If the external synchronizing voltage source (ITDC-X5:5/6)
(mode:PA6.SYX=1) is used, the signals of the zero crossovers of phase-
to-phase voltages V
L12
detection should be suppressed (PA6.INV=2).
For the 6QG3x SITOR sets, the zero crossover signals of phase-to-phase
voltages V and V
L12 L13
This is not the case for 6QG2x types. The calculated offset angle should
then be appropriately interpreted.
The synchronizing voltage is cyclically monitored and from this value the
period duration and line frequency determined.
A check is made as to whether the change in its period duration between
two consecutive measurements is less than 10 %.
For non-stable line supplies, different line supply handling methods can
be enabled by making the appropriate selection at the PA6.NCM
connector.
For example, in the operating mode PA6.NCM=2, an average value of
the period duration is generated over a parameterizable number of
measured values of the period duration. The number of measured values
used is specified at connection PA6.FAM (refer to the Table).
If larger deviations occur more frequently, then the "Synchronizing
voltage erroneous" fault message is output.
All of the frequency-dependent quantities are calculated from the new
average value of the period duration.
The gating unit calculates an internal offset angle which defines the
position of α=0° with respect to the line supply. The frequency-dependent
phase shift of the synchronizing voltage PA6.AFI, filtered through an RC
filter and the offset angle between the line supply and synchronizing
voltage PA6.XDA is included in this quantity.
The line supply frequency is emulated using a 16MHz counter (21 bit)
[16MHz] in the line supply value (50Hz
PA6.NZG. The value for 60° of the periods is calculated from this value
for 360°, and is output at PA6.Y6R.
The determined line supply frequency [Hz] is output at PA6.XFN.
If the line supply value is not smoothed (PA6.NCM=0), the line supply
frequency value actual periods can be monitored so that the line supply
frequency stability can be evaluated.
The actual phase position of the output pulses is compared with a
reference position (setpoint position), and from this a correction quantity
is determined for the pulse position.
Closed-loop thyristor current control
/V are not available so that the rotating field
L13
are smoothed and are therefore phase shifted.
= ˆ
320000) and is output at
5-11