ABB Relion 670 Series Commissioning Manual page 167

1MRK 511 403-UEN E
5. Inject a voltage U
6. Inject a load current for Transformer 1 that is equal to rated load current
load current for Transformer 2 that is equal to 95% of rated load current
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
8. Confirm the settings for C
Impedance). Using these setting values and the measured quantity of circulating current
from the local HMI (I
ci .
U
Udi
EQUATION2088 V1 EN-US
The voltage regulation algorithm then increases (for transformer
transformer
deadband limits U1 and U2 for the purposes of voltage regulation.
EQUATION2090 V3 EN-US
9. To cause a tap change, the calculated value for circulating current voltage adjustment
must offset the injected quantity for bus voltage U
deadband created by setting
EQUATION2092 V2 EN-US
EQUATION2094 V2 EN-US
Therfore:
Ci Icc i Xi U
EQUATION2096 V1 EN-US
Icc i
EQUATION2098 V1 EN-US
10. Using the settings for
short circuit impedance) calculate the magnitude of Icc
change command.
11. Inject current equal to
that the magnitude of calculated circulating current will cause a raise command to be
issued for Transformer 2 and a lower command for Transformer 1. Magnitude and
direction of circulating currents measured for each transformer can be observed as
Bay control REC670
Commissioning manual
USet for each transformer.
equal to
B
I2Base , with polarity as discussed in step 6.
i (Compensation Factor) and X i (Transformer Short Circuit
cc_i ), calculate the value for circulating current voltage adjustment
= × ×
Ci Icc i Xi _
T1 ) the measured voltage by Udi and compares Ui against the voltage
(Equation 37)
(Equation 38)
× × > -
_ 2
( )
-
U 2 Uset
>
_
(
Ci Xi
USet , UDeadband , C (Compensating factor) and Xr2 (transformer
I2Base for Transformer 1 and ( I2Base - |Icc_ i |) for Transformer 2 so
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B
UDeadband . Expressed by equation
(for the purposes of this test procedure)
Uset
)
×
Testing functionality by secondary injection
I2Base and a
I2Base . This will
T2 ) or decreases (for
so that Ui is outside the voltage
37 and equation 38.
_i necessary to cause a tap
Section 11
(Equation 35)
(Equation 36)
(Equation 39)
(Equation 40)
161