12.10.3.7 Single transformer
Load drop compensation
1. Confirm that OperationLDC is set to On.
2. Confirm settings for Rline and Xline.
3. Calculate the expected load voltage U
L
(displayed as a measured value on the
local HMI) based on secondary injection of transformer secondary voltage (U
B
=
USet) and rated load current (I
L
= I1Base), in accordance with equation
115.
EQUATION2080 V3 EN (Equation 115)
where:
U
L
, I
L
= Re(I
L
) + jlm(I
L
) are complex phase quantities
When all secondary phase-to-earth voltages are available, use the positive-
sequence components of voltage and current. By separation of real and
imaginary parts:
, , , ,ul re ub re rline il re xline il im= - × + ×
EQUATION2082 V1 EN
(Equation 116)
, , , ,ul im ub im xline il re rline il im= - × - ×
EQUATION2084 V1 EN (Equation 117)
where:
ub is the complex value of the busbar voltage
il is the complex value of the line current (secondary side)
rline is the value of the line resistance
xline is the value of the line reactance
For comparison with the set-point value, the modulus of U
L
are according to
equation
118.
¦ U
L
¦ = (ul , re)
2
+ (ul , im)
2
EQUATION2086 V2 EN
(Equation 118)
4. Inject voltage for U
B
equal to setting USet.
5. Inject current equal to rated current I2Base.
6. Confirm on the local HMI that service values for bus voltage and load current are
equal to injected quantities.
1MRK502053-UEN B Section 12
Testing functionality by secondary injection
Generator protection REG670 2.0 IEC 217
Commissioning manual
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