ABB RED615 Technical Manual page 762

Section 9
Control functions
756
stepwise change in the phase angle of the load, the regulating error can be
suppressed by an automatic setting group change or by changing the operation
mode with the logic.
Capacitor bank
connected
FALSE => Auto parallel (NRP)
TRUE => Auto single
GUID-20F51931-FED1-4E58-8BBD-4B94702F0E2A V2 EN
Figure 407: Changing the operation mode of OLATCC automatically when the
capacitor bank is connected
Comparison summary between parallel operation modes
The parallel operation modes are needed because if the parallel regulators operated
independently, at some point the transformers would become out of step with each
other.
The circulating current would increase and the line drop compensation would thus
increase for the transformer giving the highest voltage. Correspondingly, the
increasing circulating current would cause the transformer giving the lowest
voltage to decrease the voltage due to a decreased line drop compensation effect. In
other words, the two transformers would run apart.
However, it is case-specific which parallel operation mode is the most suitable.
I_A
I_B
I_C
U_AB
TR1_TAP_POS
TR2_TAP_POS
TR3_TAP_POS
RAISE_LOCAL
LOWER_LOCAL
TAPCHG_FLLW
NOT PARALLEL
AUTO
CON_STATUS
LTC_BLOCK
TCO
RSV
TR1_I_AMPL
TR1_I_ANGL
TR2_I_AMPL
TR2_I_ANGL
TR3_I_AMPL
TR3_I_ANGL
* Only for GOOSE Engineering
1YHT530004D05 D
OLATCC
RAISE_OWN
LOWER_OWN
FLLW1_CTL
FLLW2_CTL
FLLW3_CTL
BLKD_I_LOD
BLKD_U_UN
BLKD_U_OV
BLKD_I_CIR
BLKD_LTCBLK
ALARM
PAR_FAIL
PARALLEL
AUTO
TIMER_ON
TR0_I_AMPL*
TR0_I_ANGL*
615 series
Technical Manual