• T1RXOP and T2RXOP shall be set to On in instance 3 of TR8ATCC,
• T2RXOP and T3RXOP shall be set to On in instance 1 of TR8ATCC
and so on.
The parameter corresponding to the own IED must not be set.
T1RXOP should thus not be set in IED T1, T2RXOPnot in
IED T2 and so on.
3. Review the settings for UDeadband (based on percentage of nominal bus
voltage) and calculate the upper (U2) and lower (U1) voltage regulation limits
for which a tap change command will be issued from the master transformer
in the group.
4. Inject a voltage UB equal to USet for each transformer.
5. Inject a load current for Transformer 1 that is equal to rated load current
IBase (for winding 2, which is defined in a global base function, selected with
setting GlobalBaseSel2 for TR8ATCC) and a load current for Transformer 2
that is equal to 95% of rated load current IBase (for winding 2, which is
defined in a global base function, selected with setting GlobalBaseSel2 for
TR8ATCC). This will have the effect of producing a calculated circulating
current that flows from HV to LV side for Transformer 1 and LV to HV side
for Transformer 2.
6. Confirm that a circulating current is measured on the local HMI that is equal
in magnitude to 5% of IBase (for winding 2, which is defined in a global base
function, selected with setting GlobalBaseSel2 for TR8ATCC), with polarity
as discussed in step
5.
7. Confirm the settings for Ci (Compensation Factor) and Xi (Transformer Short
Circuit Impedance). Using these setting values and the measured quantity of
circulating current from the local HMI (Icc_i), calculate the value for
circulating current voltage adjustment Uci.
EQUATION2088 V1 EN (Equation 10)
The voltage regulation algorithm then increases (for transformer T2) or
decreases (for transformer T1) the measured voltage by Udi and compares Ui
against the voltage deadband limits U1 and U2 for the purposes of voltage
regulation.
EQUATION2090 V1 EN
(Equation 11)
8. To cause a tap change, the calculated value for circulating current voltage
adjustment must offset the injected quantity for bus voltage UB so that Ui is
outside the voltage deadband created by setting UDeadband. Expressed by
equation 12 and equation 13.
Section 6 1MRK 504 126-UEN -
Testing functionality
72
Commissioning Manual
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