ABB Relion REC615, Техническое руководство

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Network and the generator running in parallel with the network are connected
through the line AB. When a fault occurs between A and B, the protection relay
protection opens the circuit breakers A and B, thus isolating the faulty section
from the network and making the arc that caused the fault extinguish. The first
attempt to recover is a delayed autoreclosure made a few seconds later. Then, the
autoreclose function DARREC gives a command signal to the synchrocheck function
to close the circuit breaker A. SECRSYN performs an energizing check, as the line AB
is de-energized (
U_BUS
>
Live bus value,
U_LINE
<
Dead line value) . After verifying
the line AB is dead and the energizing direction is correct, the protection relay
energizes the line (
U_BUS
->
U_LINE
) by closing the circuit breaker A. The PLC of
the power plant discovers that the line has been energized and sends a signal to
the other synchrocheck function to close the circuit breaker B. Since both sides of
the circuit breaker B are live (
U_BUS
>
Live bus value,
U_LINE
>
Live bus value),
the synchrocheck function controlling the circuit breaker B performs a synchrocheck
and, if the network and the generator are in synchronism, closes the circuit breaker.
G
SECRSYN
DARREC
SECRSYN
PLC
A
B
U_Bus U_Bus U_Line U_Line
Figure 322: Synchrocheck function SECRSYN checking energizing conditions and
synchronism
Connections
A special attention is paid to the connection of the protection relay. Furthermore it
is checked that the primary side wiring is correct.
A faulty wiring of the voltage inputs of the protection relay causes a malfunction in
the synchrocheck function. If the wires of an energizing input have changed places,
the polarity of the input voltage is reversed (180°). In this case, the protection relay
permits the circuit breaker closing in a situation where the voltages are in opposite
phases. This can damage the electrical devices in the primary circuit. Therefore, it is
extremely important that the wiring from the voltage transformers to the terminals
on the rear of the protection relay is consistent regarding the energizing inputs
U_BUS
(bus voltage) and
U_LINE
(line voltage).
The wiring should be verified by checking the reading of the phase difference
measured between the
U_BUS
and
U_LINE
voltages. The phase difference measured
by the protection relay has to be close to zero within the permitted accuracy
tolerances. The measured phase differences are indicated in the LHMI. At the
same time, it is recommended to check the voltage difference and the frequency
1MRS758755 C Control functions
REC615 & RER615
Technical Manual
651