ABB REC650 Applications Manual page 154

Section 6
Current protection
148
Operate
Angle1(2) = 0
Power1(2)
IEC06000556 V1 EN
Figure 63: For low forward power the set angle should be 0° in the underpower
function
TripDelay1(2) is set in seconds to give the time delay for trip of the stage after pick up.
The possibility to have low pass filtering of the measured power can be made as shown in
the formula:
( )
S TD S TD S
= ⋅ + 1 − ⋅
Old Calculated
EQUATION1893-ANSI V1 EN
Where
S is a new measured value to be used for the protection function
S is the measured value given from the function in previous execution cycle
old
S is the new calculated value in the present execution cycle
Calculated
TD
is settable parameter
The value of TD=0.98 or even TD=0.99 is recommended in generator low forward power
applications as the trip delay is normally quite long. This filtering will improve accuracy
of the power function.
Q
°
en06000556.vsd
1MRK 511 286-UUS A
P
(Equation 80)
Application manual