Table 227: Complex power calculation
Set value:
Mode
Formula used for complex power calculation
L1, L2, L3
* * *
1 1 2 2 3 3L L L L L L
S U I U I U I= × + × + ×
EQUATION1697 V1 EN (Equation 88)
Arone
* *
1 2 1 2 3 3L L L L L L
S U I U I= × - ×
EQUATION1698 V1 EN (Equation 89)
PosSeq
*
3
PosSeq PosSeq
S U I= × ×
EQUATION1699 V1 EN (Equation 90)
L1L2
* *
1 2 1 2
( )
L L L L
S U I I= × -
EQUATION1700 V1 EN (Equation 91)
L2L3
* *
2 3 2 3
( )
L L L L
S U I I= × -
EQUATION1701 V1 EN (Equation 92)
L3L1
* *
3 1 3 1
( )
L L L L
S U I I= × -
EQUATION1702 V1 EN (Equation 93)
L1
EQUATION1703 V1 EN (Equation 94)
L2
EQUATION1704 V1 EN (Equation 95)
L3
EQUATION1705 V1 EN (Equation 96)
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). A start signal START1(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 start signal is still active. At activation of any of the two stages
a common signal START 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 reverse 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
Section 8 1MRK502052-UEN B
Current protection
432
Technical manual
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