Siemens 7SJ85 - 8.9 Voltage Controller; Overview of Functions; Structure of the Function

Voltage Controller
Overview of Functions
The transformer voltage controller functionality (ANSI 90V) is used to control power transformers (two-
winding transformers, three-winding transformers, grid coupling transformers) and auto transformers using a
motor-operated tap changer. The function provides automatic voltage control within a specified voltage range
on the secondary side of the transformers or, as an alternative, at a remote load point (Z compensation or R/X
compensation) in the network. In order to compensate for the voltage variations in the meshed system, use
the LDC-Z procedure (Z compensation). For voltage drops on the line, use the LDC-XandR procedure (R/X
compensation).
The control principle is based on the fact that a higher or lower command to the tap changer, as a function of
the voltage change (ΔV) per tap, causes a voltage increase or decrease.
The voltage control operates on a tap-for-tap basis and compares the measured actual voltage (Vact) to the
specified target voltage (Vtarget). If the voltage difference is greater than the set bandwidth (B), a higher or
lower command is sent to the tap changer once the set time delay (T1) has elapsed. Specifying the time delay
(T1) depends on the set controller response (inverse or linear), to avoid unnecessary adjusting commands
during brief voltage deviations from the target value and for coordination with other automatic voltage
controllers in the system.
The voltage controller function also monitors the currents on the upper-voltage side and the low-voltage side
of the transformer to block the controller during impermissible operating states (overcurrent/undercurrent/
undervoltage). The voltage controller function also has limiting values that, in special operating cases,
suppress higher commands in the case of overvoltage and lower commands in the case of undervoltage.
Structure of the Function
The Two-winding transformer voltage controller, Three-winding transformer voltage controller, and Grid
coupling transformer voltage controller function groups consist of 5 function blocks. Depending on the
application, the function groups are preconfigured in the relevant application template by the manufacturer or
can be copied into the corresponding device project during engineering.
The following figure shows, for example, the functional scope of the Two-winding transformer voltage
controller function group.
[dwvolctl-060913-01.vsd, 2, en_US]
Figure 8-96 Structure/Embedding of the Function Group
The functions General (GAPC), Tap changer (YLTC), and Voltage controller (ATCC) are logical node points in
IEC 61850-8-1.
The tap changer (YLTC) is the interface between the voltage controller (ATCC) and the motor-operated tap
changer of the transformer (OLTC). This means that the voltage controller (ATCC) sends higher and lower
commands to the tap changer. This tap changer issues command pulses to the motor-operated tap changer of
the transformer (OLTC). The tap changer (YLTC) measures the tap positions and monitors the action of the
motor-operated tap changer (OLTC).
8.9
8.9.1
8.9.2
Control Functions
8.9 Voltage Controller
1194 SIPROTEC 5, Overcurrent Protection, Manual
C53000-G5040-C017-8, Edition 07.2017