ABB REG670 Commissioning Manual page 254

Section 13
Testing functionality by secondary injection
248
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
9. To cause a tap change, the calculated value for circulating current voltage
adjustment must offset the injected quantity for bus voltage U
outside the voltage deadband created by setting UDeadband. Expressed by
equation 116 and equation 117.
(Equation 116)
EQUATION2092 V2 EN-US
(Equation 117)
EQUATION2094 V2 EN-US
Therfore:
× ×
Ci Icc i Xi U _
EQUATION2096 V1 EN-US
(
-
U 2
>
Icc i _
EQUATION2098 V1 EN-US
10. Using the settings for USet, UDeadband, C (Compensating factor) and Xr2
(transformer short circuit impedance) calculate the magnitude of Icc_i
necessary to cause a tap change command.
11. Inject current equal to I2Base for Transformer 1 and (I2Base - |Icc_i|) for
Transformer 2 so 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 service values on the local HMI and
raise/lower commands detected from the binary output mapped in the Signal
Matrix.
Generator protection REG670 2.2 IEC and Injection equipment REX060, REX061, REX062
(for the purposes of this test procedure)
> -
2 Uset
)
Uset
( )
×
Ci Xi
1MRK 502 073-UEN A
(Equation 115)
so that Ui is
B
(Equation 118)
(Equation 119)
Commissioning manual