Voltage Protection 27, 59; Measurement Principle - Siemens SIPROTEC 4 Manual

Functions

2.6 Voltage Protection 27, 59

2.6 Voltage Protection 27, 59
Voltage protection has the task to protect electrical equipment against undervoltage and overvoltage. Both
operational states are abnormal as overvoltage may cause for example insulation problems or undervoltage
may cause stability problems.
There are two elements each available for overvoltage protection and undervoltage protection.
Applications
•
Abnormally high voltages often occur e.g. in low loaded, long distance transmission lines, in islanded
systems when generator voltage regulation fails, or after full load rejection of a generator from the
system.
•
The undervoltage protection function detects voltage collapses on transmission lines and electrical
machines and prevents inadmissible operating states and a possible loss of stability.
2.6.1

Measurement Principle

Connection/Measured Values
The voltages supplied to the device may correspond to the three phase-to-ground voltages V
the two phase-to-phase voltages (V
of a single-phase connection - any phase-to-ground voltage. The connection type has been specified during
the configuration in parameter 213 VT Connect. 3ph (see Section ).
The following table indicates which voltages can be evaluated by the function. The settings for this are made
in the P.System Data 1 (see Section ). Furthermore, it is indicated to which value the threshold must be
set. All voltages are fundamental frequency values.
Table 2-8
Connection, threephase
(parameter213)
Overvoltage
Van, Vbn, Vcn
Vab, Vbc, VGnd
Vab, Vbc
Vab, Vbc, VSyn
Vab, Vbc, Vx
Vph-g, VSyn
Undervoltage
Van, Vbn, Vcn
122
, V ) and the displacement voltage (ground voltage V
A-B B-C
Voltage protection, selectable voltages
Selectable voltage
parameter 614/ 615
Vphph (largest phase-to-phase voltage)
Vph-n ((largest phase-to-ground voltage)
V1(positive sequence voltage)
V2 (negative sequence voltage)
Vphph (largest phase-to-phase voltage)
V1(positive sequence voltage)
V2 (negative sequence voltage)
None (direct evaluation of the voltage connected to
voltage input 1)
Vphph (smallest phase-to-phase voltage)
Vph-n (smallest phase-to-ground voltage)
V1 (positive sequence voltage)
, V , V
A-N B-N
) or - in the case
N
Threshold to be set as
Phase-to-phase voltage
Phase-to-ground voltage
Positive sequence voltage calculated
from
phase-to-groundvoltage or
phase-tophase voltage / √3
Negative sequence voltage
Leiter-Leiter-Spannung
Positive sequence voltage
Negative sequence voltage
Direct voltage value
Phase-to-phase voltage
Phase-to-ground voltage
Positive sequence voltage· √3
SIPROTEC 4, 7SJ80, Manual
E50417-G1140-C343-A8, Edition 12.2017
or
C-N