Siemens siprotec 7SA6 User Manual

Functions
6-737SA6 Manual
C53000-G1176-C133-1
A power swing is detected, if during the last eight measuring cycles (corresponding to
two periods), the continuity of the changing impedance vector is confirmed. In this
way, slip frequencies of up to at least 7 Hz are detected.
Power Swing
Blocking
The power swing blocking affects the distance protection. If the criteria for power
swing detection have been fulfilled in at least one phase, the following reactions are
possible in relation to the power swing blocking function (set in address 36
2SPRGH
• Blocking of all zones ($OO]RQHVEORFN):
All zones of the distance protection are blocked during a power swing.
• Blocking of the first zone only (==%EORFN):
The first zone (Z1) and the overreaching zone (Z1B) are blocked during a power
swing. Faults in other zones are tripped with the associated grading time.
• Blocking of only the higher zones (=WR=EORFN):
The higher zones (Z2 to Z5) are blocked during a power swing. Only the first and
the overreaching zone (Z1 and Z1B) remain active.
• Blocking of the first two zones (==%=EORFN):
The first and second zone (Z1 and Z2) and the overreaching zone (Z1B) are
blocked during a power swing. The higher zones Z3 to Z5 remain active.
The associated measures taken only apply to those phases in which the power swing
has been detected. They are active for as long as the measured impedance vector is
inside the power swing range PPOL, or if due to an abrupt change of the associated
impedance vector the power swing criteria are no longer satisfied.
If the distance protection recognizes a short-circuit which results in a trip, during a
power swing, this trip signal is always three-pole.
Power Swing
Tripping
If tripping in the event of an instable power swing (out-of-step condition) is desired, the
parameter 3RZHU6ZLQJWULS = <HV is set. If the criteria for power swing detection
are satisfied, the distance protection is initially blocked according to the configured
program for power swing blocking, to avoid tripping by the distance protection.
When the impedance vectors identified by the power swing detection exit the power
swing characteristic PPOL, the R components are used to check if the vectors have
the same sign as was the case when they entered the power swing characteristic. If
this is the case, the power swing process is inclined to stabilize. Otherwise, the vector
passed through the power swing characteristic (loss of synchronism, case (4) in
Figure 6-40). The device issues a three-pole trip command, thereby isolating the two
system segments from each other. Power swing tripping is alarmed.
As the operating range of the power swing supplement depends on the distance
protection settings, the power swing tripping can also only be active, when the
distance protection has been activated.
6.3.2 Applying the Function Parameter Settings
The power swing supplement is only active if it has been set to 3RZHU6ZLQJ =
(QDEOHG (address ) during the configuration.

Siemens siprotec 7SA6 Specifications

General

Brand	Siemens
Model	siprotec 7SA6
Category	Relays
Language	English