For the parallel control, the following 2 methods are available:
•
Master-Follower method
•
Method of minimizing the circulating reactive current
Table 6-28 Conditions for the Use of Both Methods
Requirements for the Transformers Requirement for the Voltage
Controller
Method
Voltage change
per tap
Rated power Short-circuit
voltage devia-
tion
Current meas-
urement
Tap position
Same Same or
different
<10 % Optional Necessary Master/Follower
Different Same or
different
Different Necessary Recommended Minimizing circu-
lating reactive
current
As the preceding table shows, before selecting the method, you must check whether the corresponding
requirements are met. If you place transformers in parallel, whose short-circuit voltages differ by more than
10 % from each other, then Siemens recommends the Method of minimizing the circulating reactive
current.
Control of the Function
You can control the Parallel control function via setting values or commands.
Parameters
Values
With setting values Parallel mode Master, No mode, Follower, Circulat. react
current
Parallel mode changeable by setting, controllable
Force master changeable by setting, controllable
With command Parallel control (ParOp) independent, parallel
Set master (ForceMast) off, on
Parallel groups (ParGrp) 1 to 4
The state of the control is reported as:
•
no mode
•
independent
•
Master
•
Follower
•
Circulating reactive current
If the parallel control is connected to further transformers via the communication, the state is checked for
correctness. If this is not the case, an inconsistency indication is issued. The communication to the trans-
formers of a group is also monitored. If a fault is present, this is reported.
Grouping
Each transformer in the parallel control is assigned to a group. You enter the name of the group via the Prop-
erties tab of the command Parallel group in the Information routing of DIGSI 5.
Control Functions
6.9 Voltage Controller
466 SIPROTEC 5, High-Voltage Bay Controller, Manual
C53000-G5040-C015-9, Edition 11.2017
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