ABB RELION REX640 Technical Manual page 1421

1MRS759142 C
REX640
Technical Manual
means the reference side voltage is lower than the running side voltage. So the voltage
matching generates the voltage lower command pulse LOWER_U.
The length of the voltage raise and lower command pulse (tpU) and the pulse off
interval (tsU) are calculated based on the setting Voltage match mode.
Voltage matching in manual mode
If Auto Syn mode is set to "Manual mode", the voltage raise or lower command pulses
are generated manually from the function's user commands.
If the command AVR voltage raise is set to "RAISE", the function activates the voltage
raise command pulse RAISE_U. If the command AVR voltage lower is set to
"LOWER", the function activates the voltage lower command pulse LOWER_U.
The lengths of these generated pulses tpU and pulse off interval tsU are based on the
settings as: tpU = Volt pulse Min Dur; tsU = Volt pulse off Intv.
Voltage matching with variable command pulse lengths
When the setting Voltage match mode is set to "Variable Pulse", the voltage matching
is done with variable command pulse lengths.
The voltage matcher issues a command with a length proportional to the voltage
difference. The proportionality factor setting Volt rate of change (dU/dt) can be
adapted to the voltage regulator. The voltage matcher aims at a value in the middle of
the set tolerance band.
The adjusting voltage command pulse length tpU is calculated as
U max
 + ∆ − −
U
∆ −

2

tpU
=
dU
dt
GUID-E12141B6-5B7F-44BB-BFC6-0512A51E9DDF V1 EN
ΔU Measured voltage difference across the CB to be synchronized
Voltage Diff Ov Ex
+ΔUmax Setting
Voltage Diff Un Ex
-ΔUmax Setting
Volt rate of change
dU/dt Setting
The adjusting pulse is discontinued as soon as the voltage difference exceeds the target
value. The command length does not fall below a settable minimum value Volt pulse
Min Dur. After an adjusting command, the system waits for the set Volt pulse off Intv
(tsU) so that the actual values can stabilize to the new set point.
U max
∆ 


Section 9
Control functions
(Equation 325)
1415