•
T1RXOP and T2RXOP shall be set to On in instance 3 of TR8ATCC,
•
T2RXOP and T3RXOP shall be set to On in instance 1 of TR8ATCC and so on.
The parameter corresponding to the own IED must not be set.
T1RXOP
should thus not be set in IED
T1, T2RXOPnot in IED T2 and so on.
3.
Review the settings for
UDeadband (based on percentage of nominal bus voltage) and
calculate the upper (U2) and lower (U1) voltage regulation limits for which a tap change
command will be issued from the master transformer in the group.
4.
Review the expected time for first (
t1) and subsequent (t2) tap change commands from
the master transformer in the local HMI under Main menu/Settings/Setting group N/
TransformerVoltageControl(ATCC,90)/TR1ATCC:x/TR8ATCC:x/Time/t1 and t2
5.
Inject a voltage U
B
equal to
USet for each transformer.
6.
Inject a load current for Transformer 1 that is equal to rated load current
I2Base and a
load current for Transformer 2 that is equal to 95% of rated load current
I2Base. This will
have the effect of producing a calculated circulating current that flows from HV to LV
side for Transformer 1 and LV to HV side for Transformer 2.
7.
Confirm that a circulating current is measured on the local HMI that is equal in magnitude
to 5% of
I2Base, with polarity as discussed in step
8.
Confirm the settings for C
i (Compensation Factor) and Xi (Transformer Short Circuit
Impedance). Using these setting values and the measured quantity of circulating current
from the local HMI (I
cc_i), calculate the value for circulating current voltage adjustment
U
ci.
_
Udi Ci Icc i Xi
=
×
×
EQUATION2088 V1 EN-US
(Equation 119)
The voltage regulation algorithm then increases (for transformer
T2) or decreases (for
transformer
T1) the measured voltage by Udi and compares Ui against the voltage
deadband limits U1 and U2 for the purposes of voltage regulation.
EQUATION2090 V3 EN-US
(Equation 120)
9.
To cause a tap change, the calculated value for circulating current voltage adjustment
must offset the injected quantity for bus voltage U
B
so that Ui is outside the voltage
deadband created by setting
UDeadband. Expressed by equation
EQUATION2092 V2 EN-US
(Equation 121)
EQUATION2094 V2 EN-US
(Equation 122)
(for the purposes of this test procedure)
Therfore:
_
2
Ci Icc i Xi U
Uset
×
×
>
-
EQUATION2096 V1 EN-US
(Equation 123)
Section 12
1MRK 502 067-UEN B
Testing functionality by secondary injection
218
Commissioning manual
