Siemens 6MD85, Manual

Page: 1089 / 1256

Checking the Tap Direction and the Set Bandwidth
•
Set the bandwidth according to the formula in chapter 6.9.4.3 Voltage Controller .
The tap direction and the set bandwidth are checked with the following functional test.
With the correct tap direction, there will be a voltage increase when changing to a higher tap or a voltage
reduction when changing to a lower tap.
•
First switch the voltage controller to the
Manual
operating mode.
•
Switch the tap changer to a higher or lower tap on the on-site operating panel or in the DIGSI Online-
Editor until the voltage set point value is reached.
•
Keep switching the tap changer higher until the bandwidth is exceeded.
The difference in the control deviation ∣ΔV(n+1) - ΔV(n)∣ at a tap setting must be smaller than double the
bandwidth.
•
Switch the voltage controller to the
Auto
operating mode.
After the parameterized time
T1
, the voltage controller should change to lower taps until the control
deviation drops below the bandwidth.
•
Switch the voltage controller back to the
Manual
operating mode.
Keep switching the tap changer lower until the value drops below the bandwidth. The difference in the
control deviation ∣ΔV(n-1) - ΔV(n)∣ at a tap setting must be smaller than double the bandwidth.
•
Switch the voltage controller to the
Auto
operating mode.
After the parameterized time
T1
, the voltage controller must change to higher taps until the control devi-
ation drops below the bandwidth.
Checking the Circulating Reactive Current Sensitivity in Parallel Operation
The prerequisites for correct function of the parallel operation are the commissioning of the voltage controller
in single operation and that the secondary tests have been completed.
For the functional test, the voltage controllers must be in the same parallel group according to the topology
and the
Manual
mode as well as the Method of minimizing the circulating reactive current must be acti-
vated. In most cases, the default setting of the parameter
Reactive I control factor
is sufficient, since
an optimal adjustment to the configuration takes place because of the entry of the parameter
General
:
Imp(Z): short circuit imp.
of the transformer.
If the control deviation is still larger than double the bandwidth due to the circulating reactive current at a tap-
position difference of 1, alternating tap changing may take place. In this case, reduce the parameter
Reac-
tive I control factor
.
i
i
NOTE
Carry out the following tests only at low load current.
•
With all voltage controllers, approach
one
tap position which corresponds to the same no-load voltage to
keep the circulating reactive current as low as possible and to reach the voltage set point value.
•
Set one of the tap changers to a higher or lower tap. This results in a circulating reactive current.
–
If the difference of the circulating reactive current control deviation ∣ΔV
actK
(n+1) - ΔV
actK
(n)∣ is
smaller than the set bandwidth, increase the parameter
Reactive I control factor
.
– If the difference of the circulating reactive current control deviation ∣ΔV
actK
(n+1) - ΔV
actK
(n)∣ is larger
than double the bandwidth, reduce the parameter
Reactive I control factor
.
•
Repeat this test for all voltage controllers.
Functional Tests
10.10 Commissioning Hints for Voltage Control
SIPROTEC 5, High-Voltage Bay Controller, Manual 1089
C53000-G5040-C015-9, Edition 11.2017