ABB Relion 670 series - Page 479

Set value: Mode Formula used for complex power calculation
BC
* *
( )
BC B C
S V I I= × -
EQUATION2059-ANSI V1 EN (Equation 101)
CA
* *
( )
CA C A
S V I I= × -
EQUATION2060-ANSI V1 EN (Equation 102)
A
*
3
A A
S V I= × ×
EQUATION2061-ANSI V1 EN (Equation 103)
B
*
3
B B
S V I= × ×
EQUATION2062-ANSI V1 EN (Equation 104)
C
*
3
C C
S V I= × ×
EQUATION2063-ANSI V1 EN (Equation 105)
The active and reactive power is available from the function and can be used for
monitoring and fault recording.
The component of the complex power S = P + jQ in the direction Angle1(2) is
calculated. If this angle is 0° the active power component P is calculated. If this angle
is 90° the reactive power component Q is calculated.
The calculated power component is compared to the power pick up setting Power1(2).
For directional underpower protection, a pickup signal PICKUP1(2) is activated if the
calculated power component is smaller than the pick up value. For directional
overpower protection, a pickup signal PICKUP1(2) is activated if the calculated power
component is larger than the pick up value. After a set time delay TripDelay1(2) a trip
TRIP1(2) signal is activated if the pickup signal is still active. At activation of any of
the two stages a common signal PICKUP will be activated. At trip from any of the two
stages also a common signal TRIP will be activated.
To avoid instability there is a settable hysteresis in the power function. The absolute
hysteresis of the stage1(2) is Hysteresis1(2) = abs (Power1(2) + drop-power1(2)). For
generator low forward power protection the power setting is very low, normally down
to 0.02 p.u. of rated generator power. The hysteresis should therefore be set to a
smaller value. The drop-power value of stage1 can be calculated with the Power1(2),
Hysteresis1(2): drop-power1(2) = Power1(2) + Hysteresis1(2)
For small power1 values the hysteresis1 may not be too big, because the drop-
power1(2) would be too small. In such cases, the hysteresis1 greater than (0.5 ·
Power1(2)) is corrected to the minimal value.
1MRK505222-UUS C Section 7
Current protection
473
Technical reference manual