• Area B defines the linear growth recovery voltage level from
Voltage level 1
to
Voltage level 2
in a time period from
Recovery time 1
to
Recovery time 2
.
• Area C is the zone where voltage stabilizes.
Voltage level 3
is defined to same
value as
Voltage level 2
. The system should remain above this voltage in a time
period from
Recovery time 2
to
Recovery time 3
.
The system restores to a normal state and function resets when the voltage is equal
or greater than
Voltage level 4
after
Recovery time 4
time period.
When the voltage at the point of common coupling is above the LVRT curve, the
generation unit must remain connected, and must be disconnected only if the
voltage takes values below the curve.
Figure 507: A typical required ride-through voltage capability of generating unit
The LVRT requirement depends on the power system characteristics and the
protection employed, varying significantly from each other. The requirement also
differs from country to country. LVRTPTUV function incorporates four types of LVRT
curves which satisfy most of the power system needs. Grid operators can fine-tune
the LVRT curve by setting the parameters as per their requirement, making the
use simpler in comparison with different conventional undervoltage protection with
different operate time setting and logics.
4.5.8.7 Signals
LVRTPTUV Input signals
Table 854: LVRTPTUV Input signals
Name
Type Default Description
U3P SIGNAL - Three-phase voltages
BLOCK BOOLEAN 0=False Block signal for acti-
vating the blocking
mode
1MRS759142 F Protection functions
REX640
Technical Manual
905
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