Application - ABB RED615 Technical Manual

1YHT530004D05 D
9.3.5
615 series
Technical Manual
Voltage angle difference adjustment
In application where the power transformer is located between the voltage
measurement and the vector group connection gives phase difference to the
voltages between the high and low-voltage sides, the angle adjustment can be used
to meet synchronism.
The vector group of the power transformer is defined with clock numbers, where
the value of the hour pointer defines the low voltage-side phasor and the high voltage-
side phasor is always fixed to the clock number 12, which is same as zero. The
angle between clock numbers is 30 degrees. When comparing phase angles, the
U_BUS input is always the reference. This means that when the Yd11 power
transformer is used, the low voltage-side voltage phasor leads by 30 degrees or lags
by 330 degrees the high voltage-side phasor. The rotation of the phasors is
counterclockwise.
The generic rule is that a low voltage-side phasor lags the high voltage-side phasor
by clock number * 30º. This is called angle difference adjustment and can be set
for SECRSYN with the Phase shift setting.

Application

The main purpose of the synchrocheck function is to provide control over the
closing of the circuit breakers in power networks to prevent the closing if the
conditions for synchronism are not detected. This function is also used to prevent
the reconnection of two systems which are divided after islanding and a three-pole
reclosing.
The Synchro check function block includes both the synchronism check function
and the energizing function to allow closing when one side of the breaker is dead.
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 IED 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 IED 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.
Section 9
Control functions
687