ABB RELION REX640, Техническое руководство, Страница: 910 / 1960

The recommended and the default value for
Phase supervision is “Pos
sequence”.
If the magnitude of the voltage level of any of the monitored voltage signal, defined
by the
Phase supervision setting, drops below Under Volt Blk value or exceeds Over
Volt Blk value, the calculation of vector shift is disabled and the
INT_BLKD
output is
activated.
The function is blocked and
LOWAMPL_BLKD
is activated, if the measured frequency
deviates ±5% from the nominal value.
The magnitude of calculated vector shift for three phase-to-earth or phase-
to-phase voltages, USHIFT_A_AB, USHIFT_B_BC and USHIFT_C_CA or positive
sequence voltage U1SHIFT, which resulted in the activation of last
OPERATE
output,
are available in the Monitored data view.
The activation of
BLOCK
input deactivates the
INT_BLKD
output.
Figure 510: Vector shift during Loss of Mains
Pulse timer
Once the Pulse timer is activated, it activates the
OPERATE
output. The pulse length
of
OPERATE
is fixed to 100 ms.
The activation of the
BLOCK
input deactivates the
OPERATE
binary output and resets
the timer.
4.5.9.6 Application
Use of distributed generation ( DG) units is increasing due to liberalized markets
(deregulation) and the global trend to use more renewable sources of energy. They
generate power in the range of 10 kW...10 MW and most of them are interconnected
to the distribution network. They can supply power into the network as well as to
the local loads. It is not common to connect generators directly to the distribution
networks and thus the distributed generation can cause some challenges for the
protection of distribution networks. From the protection point of view, one of the
most challenging issue is islanding.
Islanding is defined as a condition in which a distributed generation unit continues
to supply power to a certain part of the distribution network when power from the
Protection functions 1MRS759142 F
910 REX640
Technical Manual