ABB RELION REX640 Technical Manual page 1048

Protection functions
Z =
1
The calculated positive-sequence impedance amplitude Z1_AMPL and angle
Z1_ANGLE are available in primary ohms and degrees, respectively, in the Monitored
data view.
Power swing detection
Power swing detection function comprises an inner and outer quadrilateral /circular
measurement characteristic. The positive sequence impedance is continuously
monitored for detecting a power swing condition. During normal power system
operation, the impedance is outside of outer characteristic. When the impedance
enters outer characteristic, output SWING_ST is activated, and the power swing
detection timer is triggered. The SWING_ST output will be deactivated if the
impedance leaves the zone between inner and outer characteristic. If the impedance
remains between the inner and outer characteristics longer than the time defined
by the setting
PSB is activated. The PSB output will be deactivated after the impedance leaves
outer characteristic for the time defined by
When an unbalanced fault occurs during power swing, the PSB output should
be deactivated to allow tripping. For the purpose module is monitoring negative
sequence current which is calculated from fundamental frequency three phase
currents. Negative sequence current level can be monitored if
is set to "Enable". When the negative sequence current is above the
current setting longer than the time delay defined by the setting Neg Seq current
time , the Power swing detection module is disabled. The module is disabled until
negative sequence current drops below the setting value. The
setting should be set above the maximum negative sequence current which may
appear during power swing.
Slow power swing can be used as criterion for disabling power swing detection.
Monitoring is activated by setting
sequence impedance enters and remains inside outer characteristic longer than
the time delay defined by the setting
module is disabled. The module is disabled until the positive sequence impedance
moves outside outer characteristics. The setting
coordinated with network or cable current rating characteristics. Too long lasting
large current may need to be cleared even if situation is classified as power swing.
In case of heavily loaded lines, the optional load encroachment logic can be enabled
with the
defined by the
Rv Ld Ris Rch, Load angle1 and Load angle2 settings.
Quadrilateral characteristic
If the
characteristic.
1048
U
1
I
1
The calculated impedance is converted to ohms as the operating
characteristics are defined with the ohm settings.
Swing time , and the impedance enters inner characteristic, output
Load discrimination setting. The logic reserves an area for load impedance
Outer Fw Ld Ris Rch, Outer Rv Ld Ris Rch, Inner Fw Ld Ris Rch, Inner
Pe Swg impedance Chr is 'Quadrilateral', DSTRPSB has a double-polygon
Pulse time setting.
Slow swing Spvn to "Enable". If the positive
Slow swing time , the Power swing detection
Slow swing time should be
1MRS759142 F
(Equation 281)
Ng Seq current Spvn
Max Ng Seq
Max Ng Seq current
REX640
Technical Manual