ABB RELION RET670, Commissioning Manual, Page: 262 / 328

_ Vdi Ci Icc i Xi
= × ×
EQUATION2089-ANSI V1 EN
(Equation 112)
The voltage regulation algorithm then increases (for transformer T2 ) or decreases
(for transformer T1 ) the measured voltage by Vdi and compares Vi against the
voltage deadband limits V1 and V2 for the purposes of voltage regulation.
Vi VB Vdi
= +
EQUATION2091-ANSI V1 EN
(Equation 113)
9. To cause a tap change, the calculated value for circulating current voltage
adjustment must offset the injected quantity for bus voltage V
B
so that Vi is outside
the voltage deadband created by setting VDeadband . Expressed by equation 114 and
equation 115 .
2 Vdi V VB
> -
EQUATION2093-ANSI V1 EN
(Equation 114)
VB Vset
=
EQUATION2095-ANSI V1 EN
(Equation 115)
(for the purposes of this test procedure)
Therfore:
_ 2 Ci Icc i Xi V Vset
× × > -
EQUATION2097-ANSI V1 EN
(Equation 116)
( )
( )
2
_
V Vset
Icc i
Ci Xi
-
>
×
EQUATION2099-ANSI V1 EN
(Equation 117)
10. Using the settings for VSet , VDeadband , 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
Section 11
1MRK 504 165-UUS -
Testing functionality by secondary injection
256 Transformer protection RET670 2.2 ANSI
Commissioning manual