ABB Relion 670 Series RES670, Technical Manual

Page: 261 / 888

Set value: Mode Formula used for complex power calculation
CA
* *
( )
CA C A
S V I I
= × -
EQUATION2060-ANSI V1 EN
(Equation 33)
A
*
3
A A
S V I
= × ×
EQUATION2061-ANSI V1 EN
(Equation 34)
B
*
3
B B
S V I
= × ×
EQUATION2062-ANSI V1 EN
(Equation 35)
C
*
3
C C
S V I
= × ×
EQUATION2063-ANSI V1 EN
(Equation 36)
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.
1MRK 511 365-UUS A
Section 8
Current protection
Phasor measurement unit RES670 2.1 ANSI 255
Technical manual