Voltage Instability Mitigation - ABB REL650 Applications Manual

1MRK 506 334-UUS A
8.1.3.4
8.1.3.5
8.1.3.6
Application manual

Voltage instability mitigation

This setting is very much dependent on the power system characteristics, and thorough
studies have to be made to find the suitable levels.
Backup protection for power system faults
The setting must be below the lowest occurring "normal" voltage and above the highest
occurring voltage during the fault conditions under consideration.
Settings for Two step undervoltage protection
The following settings can be done for two step undervoltage protection (UV2PTUV ,27).
GlobalBaseSel: Selects the global base value group used by the function to define (IBase),
(VBase) and (SBase).
ConnType: Sets whether the measurement shall be phase-to-ground fundamental value,
phase-to-phase fundamental value, phase-to-ground RMS value or phase-to-phase RMS
value.
Operation: Disabled/Enabled.
UV2PTUV (27) measures selectively phase-to-ground voltages, or phase-to-phase
voltage chosen by the setting ConnType.
This means operation for phase-to-ground voltage if:
< ×
V (%) VBase kV ( )
3
EQUATION1711 V1 EN
and operation for phase-to-phase voltage if:
< ×
Vpickup (%) VBase(kV)
EQUATION1991-ANSI V1 EN
Characteristic1: This parameter gives the type of time delay to be used for step 1. The
setting can be. Definite time/Inverse Curve A/Inverse Curve B. The choice is highly
dependent of the protection application.
OpModen: This parameter describes how many of the three measured voltages that should
be below the set level to give operation for step n (n=step 1 and 2). The setting can be 1
out of 3, 2 out of 3 or 3 out of 3. It is sufficient that one phase voltage is low to give
Section 8
Voltage protection
(Equation 164)
(Equation 165)
257