U
U
U
U
U
p
s
z
ci
rsv
=
+
+
−
(Equation 184)
U
p
Control voltage
U
s
Set voltage level
Band center voltage
U
z
Line drop compensation term
U
ci
Circulating current compensation term
U
rsv
Voltage reduction parameter
U
p
can be directly read in the monitored data U_CTL.
The circulating current compensation term is calculated only in the parallel acting
operation modes "NRP" and "MCC".
Line Drop Compensation (LDC)
The line drop compensation feature is used to compensate the voltage drop along
a line or network fed by the transformer. The compensation setting parameters can
be calculated theoretically if the resistance and reactance of the line are known or
measured practically from the line drop.
I
L
X
L
R
L
U
B
U
L
Load
Figure 560: Equivalent electrical circuit for calculating the LDC term
The compensation parameters
Line drop V Ris (U
r
) and
Line drop V React (U
x
), are
percentage values of U
n
according to the equations.
Line drop V Ris
U
I
R
U
Line dro
r
CT
n
VT n
=
[ ]
=
⋅
⋅
⋅
[
]
%
_
_
3
100
1
1
%U
n
p
p V React
U
I
X
U
U
x
CT n
VT
n
n
=
[ ]
=
⋅
⋅
⋅
[
]
%
%
_
_
3
100
1
1
(Equation 185)
I
CT_n1
Nominal primary current of the CT
U
VT_n1
Nominal primary voltage of the VT (phase-to-phase voltage)
R
Resistance of the line, Ω/phase
X
Reactance of the line, Ω/phase
The general LDC equation can be calculated.
U
I
I
U
U
z
injected
n
r
x
=
⋅
[ ]
+
[ ]
(
)
[
]
% cos
% sin
ϕ
ϕ
100
xU
n
(Equation 186)
Control functions
1MRS757644 H
1052
620 series
Technical Manual
