Siemens 6MD85, Руководство пользователя

Страница: 474 / 1256

X
k
Reactance of the transformer
B
p
Total susceptance (total susceptance value) of all parallel transformers (sum of the reciprocals
of the transformer reactance)
B
k
Susceptance of the transformer (reciprocal of the reactance)
V
rated
Rated voltage of the transformer
With the parameter
Reactive I control factor
, you can adjust the control deviation D
CRCk
so that the
circulating reactive current caused by a tap difference results in exceeding the control bandwidth. A
Reac-
tive I control factor
set too high can affect the control stability. In most cases, control quality and
control stability are assured with the default setting of 1.
The sum of the control deviation resulting from voltage deviation D
V
and the control deviation D
CRCk
, caused by
the circulating reactive current, results in:
D
k
= D
CRCk
+ D
V
and is compared with the set bandwidth. The following 2 diagrams show the summations of the control devia-
tion at negative and positive voltage deviation. A possible control deviation is caused by the circulating reac-
tive current. The circulating reactive current on transformer T
1
is in opposite to transformer T
2
. This results for
both voltage controllers in a different total deviation.
Negative voltage deviation -D
V
Changing to higher tap of T
2
with D
V
+ D
CRC2
< -B
Positive voltage deviation D
V
Changing to lower tap of T
1
with D
V
+ D
CRC1
> B
For the calculation of the voltage deviation, the voltages of all voltage controllers are transferred with GOOSE
as a measured value and an average value is calculated. The voltage can be monitored. If the data are not
plausible, the voltage controller is blocked after a settable time delay.
Error Behavior
If the value of the circulating reactive current exceeds the threshold value
Circul. current threshold
for a longer time than the set time delay
Circul. current time delay
, the indication
Circul.
current blocking
is issued and the voltage control blocked.
If the circulating reactive current value drops below the preset value, the signal is automatically reset. You can
achieve this by manually controlling the tap changer.
Blocking the Tap Changer in Case of a Fault
To activate the supervision functions in Follower mode, if the transformer differential protection is used, you
must set the parameter
Blocking
to
Auto-Manual
in the Voltage controller function.
Control Functions
6.9 Voltage Controller
474 SIPROTEC 5, High-Voltage Bay Controller, Manual
C53000-G5040-C015-9, Edition 11.2017