ABB REG670 Applications Manual page 565

1MRK 502 071-UEN -
Generator protection REG670 2.2 IEC and Injection equipment REX060, REX061, REX062
Application manual
T1
I
T1
U
B
I L
Load
U
L
en06000486.vsd
IEC06000486 V1 EN
Figure 286: Parallel transformers with equal rated data.
In the reverse reactance method, the line voltage drop compensation is used. The
original of the line voltage drop compensation function purpose is to control the
voltage at a load point further out in the network. The very same function can also be
used here to control the voltage at a load point inside the transformer, by choosing a
negative value of the parameter Xline.
Figure 287, shows a vector diagram where the principle of reverse reactance has been
introduced for the transformers in figure 286. The transformers are here supposed to
be on the same tap position, and the busbar voltage is supposed to give a calculated
compensated value U that coincides with the target voltage USet.
L
I =I =(I
T1 T2 T1
IEC06000485 V3 EN
Figure 287: Vector diagram for two transformers regulated exactly on target
voltage.
T2
I
T2
R I =R I
L T1 L T2
jX I =jX
L T1 L
U
B
+I )/2
T2
IEC06000485_2_en.vsd
Section 15
I
T2
Control
559