Compensation of tap changer position
The position of the tap changer used for voltage control can be compensated and the
position information is provided for the protection function through the tap position
indication function 84T.
Typically, the tap changer is located within the high voltage winding, that is, winding 1,
of the power transformer. The
Tapped winding
parameter specifies whether the tap
changer is connected to the high voltage side winding or the low voltage side winding.
This parameter is also used to enable and disable the automatic adaptation to the tap
changer position. The possible values are "Not in use", "Winding 1" or "Winding 2".
The
Tap nominal
parameter tells the number of the tap, which results in the nominal
voltage (and current). When the current tap position deviates from this value, the input
current values on the side where the tap changer resides are scaled to match the currents
on the other side.
A correct scaling is determined by the number of steps and the direction of the deviation
from the nominal tap and the percentage change in voltage resulting from a deviation of
one tap step. The percentage value is set using the
Step of tap
parameter.
The operating range of the tap changer is defined by the
Min winding tap
and
Max winding
tap
parameters. The
Min winding tap
parameter tells the tap position number resulting in
the minimum effective number of winding turns on the side of the transformer where the
tap changer is connected. Correspondingly, the
Max winding tap
parameter tells the tap
position number resulting in the maximum effective number of winding turns.
The
Min winding tap
and
Max winding tap
parameters help the tap position compensation
algorithm know in which direction the compensation is being made. This ensures also that
if the current tap position information is corrupted for some reason, the automatic tap
changer position adaptation does not try to adapt to any unrealistic position values.
GUID-317C68F8-A517-458A-A5D0-32FCE6C5F547 V1 EN
Figure 250:
Simplified presentation of the high voltage and medium voltage windings
with demonstration of the Max winding tap, Min winding tap and Tap
nominal parameters
1MAC059074-MB A
Section 4
Protection functions
615 series ANSI
505
Technical Manual
Summary of Contents for Relion 615 series
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