Low Pass Filtering - ABB REG650 Technical Manual

Section 8
Current protection
8.7.4.1
232
Mode
Set value:
CA
A
B
C
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 hysteresis in the power function. The absolute hysteresis
for stage 1(2) is 0.5 p.u. for Power1(2) ≥ 1.0 p.u., else the hysteresis is 0.5 Power1(2).
If the measured power drops under the (Power1(2) - hysteresis) value, the over-power
function will reset after 0.06 seconds. If the measured power comes over the
(Power1(2) + hysteresis) value, the under-power function will reset after 0.06 seconds.
The reset means that the pickup signal will drop out and that the timer of the stage will
reset.

Low pass filtering

In order to minimize the influence of the noise signal on the measurement it is possible
to introduce the recursive, low pass filtering of the measured values for S (P, Q). This
Formula used for complex power calculation
* *
= × -
S V ( I I )
CA C A
EQUATION2060-ANSI V1 EN
*
= × ×
S 3 V I
A A
EQUATION2061-ANSI V1 EN
*
= × ×
S 3 V I
B B
EQUATION2062-ANSI V1 EN
*
= × ×
S 3 V I
C C
EQUATION2063-ANSI V1 EN
1MRK 502 043-UUS B
(Equation 63)
(Equation 64)
(Equation 65)
(Equation 66)
Technical Manual