Siemens 6MD85, Manual

Page: 452 / 1256

This function is designed to control the following:
•
For two-winding transformers (2W): the voltage on the secondary circuit of the power transformer and
parallel control of several transformers feeding the same busbar or a nodal point of a system
•
For three-winding transformers (3W): the voltage of the secondary winding 1 or winding 2
•
For grid coupling transformers (GC): voltage of winding 1 or winding 2, selectively depending on the
power direction
Control operation is based on a step-by-step principle. To move the tap changer one position higher or lower,
a single control pulse is issued to the motor-drive mechanism of the tap changer. The length of the control
pulse can be set over a large range so as to handle the different types of tap-changer drives. The control pulse
is issued if the measured voltage deviates from the set reference value by more than the preset voltage range
for more than a given time period.
The voltage can be controlled at the voltage measuring point or at the load point in the electrical power
system. In this case, the load-point voltage is calculated on the basis of the measured load current and the
known impedance between the voltage measuring point and the load point.
The following figures show possible configurations of the voltage controller for two-winding transformers
with and without current measurement.
[dwkonlst-060913.vsd, 1, en_US]
Figure 6-118 Voltage-Controller Constellation for Two-Winding Transformers with Current Measurement for
Load Compensation at the End of the Line
(1) Only if a transformer side is present
Control Functions
6.9 Voltage Controller
452 SIPROTEC 5, High-Voltage Bay Controller, Manual
C53000-G5040-C015-9, Edition 11.2017