Testing The Ldc Function - ABB RET670 Installation And Commissioning Manual

Section 14
Primary injection testing
14.1.1.2
206
to the VCTR function for the purposes of voltage regulation. This voltage will be
lower (if resitive or inductive load current is applied) than the Uset voltage and
VCTR will increase the voltage in order to achieve the correct system voltage at
the load point.
Procedure
1. Confirm that the LDC function is set to On in the local HMI under Main
menu/Settings/Setting group N/Control/
TransformerVoltageControl(ATCC,90)/VCSx/VCPx/LDC/
OperationLDC
2. Set (or confirm settings for) the line data (RL + j XL) to the load point in the
local HMI under Main menu/Settings/Setting group N/Control/
TransformerVoltageControl(ATCC,90)/VCSx/VCPx/LDC/RLine and
XLine
3. Check the position of the tap changer.
4. Read the bus and load voltage from the local HMI under Main menu/
Control/Commands/TransformerVoltageControl(ATCC,90)/VCSx/
VCPx. Note the values and the difference. The voltage at the busbar will be
the system voltage corresponding to Uset. At load point it will be lower than
the system voltage.
5. Set R and XL for the LDC to 0 (Zero).
6. Check the bus and load voltage in the local HMI and confirm that both are
higher than the first readings. At load point it will be the system voltage and
at the busbar the system voltage increased with the line voltage drop. VCTR
shall have also operated during these setting changes.

Testing the LDC function

Procedure
1. Confirm the settings in the Parameter Setting tool for USet and UDeadband
2. Set Rline and Xline for the LDC to Zero.
3. Manually operate the tap changer so that the voltage at the transformer (UB)
corresponds to the regulating value USet.
Check that neither the raise command nor the lower command are operating.
This can be confirmed by checking the signals from the configured binary
outputs and the event report on the local HMI. The test of the LDC should be
carried out with a single current at one time from the main current
transformers in L1 and L3 phase.
3.1. When measuring the current from the L1 phase, the main CT in L3
phase must have its secondary winding short circuited and the cables to
the IED disconnected.
3.2. When measuring the current from the L3 phase, the main current
transformer in L1 phase must have its secondary winding short-
circuited and the cables to the IED disconnected.
4. Modify the connections according to step a above.
1MRK 504 088-UEN C
Installation and commissioning manual