Synchronism Check - ABB RELION 670 SERIES Applications Manual

1MRK 506 369-UUS -
15.1.2.2
Line distance protection REL670 2.2 ANSI
Application manual
phases used for SESRSYN, with the settings SelPhaseBus1, SelPhaseBus2,
SelPhaseLine2 and SelPhaseLine2, a compensation is made automatically for the voltage
amplitude difference and the phase angle difference caused if different setting values are
selected for the two sides of the breaker. If needed an additional phase angle adjustment
can be done for selected line voltage with the PhaseShift setting.

Synchronism check

The main purpose of the synchronism check function is to provide control over the closing
of circuit breakers in power networks in order to prevent closing if conditions for
synchronism are not detected. It is also used to prevent the re-connection of two systems,
which are divided after islanding and after a three pole reclosing.
Single pole auto-reclosing does not require any synchronism check since
the system is tied together by two phases.
SESRSYN (25) function block includes both the synchronism check function and the
energizing function to allow closing when one side of the breaker is dead. SESRSYN (25)
function also includes a built in voltage selection scheme which allows adoption to
various busbar arrangements.
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Figure 298: Two interconnected power systems
Figure 298 shows two interconnected power systems. The cloud means that the
interconnection can be further away, that is, a weak connection through other stations. The
need for a check of synchronization increases if the meshed system decreases since the
risk of the two networks being out of synchronization at manual or automatic closing is
greater.
The synchronism check function measures the conditions across the circuit breaker and
compares them to set limits. Output is generated only when all measured conditions are
within their set limits simultaneously. The check consists of:
Section 15
Control
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