ABB Relion 670 Series Applications Manual page 399

1MRK 511 401-UUS F
current lags the busbar voltage V
Rline and Xline is designated j1.
ANSI06000626 V1 EN-US
Figure 186: Transformer with reverse reactance regulation and no circulating current
The voltage DV=V
less than -90°, then V
of the transformer load current I
control regulates the voltage towards a set target value, representing a voltage magnitude,
without considering the phase angle. Thus, V
said to be on the target value.
Assume that we want to achieve that j
D = ´
V Z I
ß
0
-
j 90
D
Ve
ß
0
- = j
90
1
ß
j j
= - -
1
EQUATION1983-ANSI V1 EN-US
If for example cosj = 0.8 then j = arcos 0.8 = 37°. With the references in figure 186, j will be
negative (inductive load) and we get:
j = - -
( 37 ) 90
1
EQUATION1939 V1 EN-US
To achieve a more correct regulation, an adjustment to a value of j2 slightly less than -90° (2 – 4°
less) can be made.
Bay control REC670
Application manual
Rline
j
1
Xline Zline
j
I
T
Rline +j I
-V =I *
B L T
will have approximately the same length as V
L
j j j j
+
j j j ( )
= ´ =
Ze Ie ZIe
1 1
+ j
0
90
- = -
0 0 0
53
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with the power factor j and the argument of the impedance
B
Xline has the argument j2 and it is realised that if j2 is slightly
*
T
(indicated with the dashed line). The automatic tap change
T
as well as V
B
= -90°, then:
2
I *Rline
T
V
L
jI *Xline
T
DV
V
j
B
2
en06000626_ansi.vsd
regardless of the magnitude
B
and also the dashed line could all be
L
Section 14
Control
(Equation 129)
(Equation 130)
393