GE MiCOM P40 Agile User Manual

The Out-of-Step tripping time delay (Tost), delays the OST tripping command until the angle between internal
voltages between the two ends are at 240 degrees closing towards 360 degrees. This limits the voltage stress
across the circuit breaker. If a fault occurs during the swing condition, the Out-of-Step tripping function is blocked.
The Out-of-Step algorithm is completely independent from the distance elements and the power swing detection
function. The load blinder does not affect the OST characteristics. In common with other similar functions, a
minimum positive sequence current of 5%In is needed for Out-of-Step operation.
4.3
OUT OF STEP LOGIC DIAGRAM
V02761
Fault detected
OST Mode
OST Disabled
Pred. OST Trip
Pred. OST
OST Trip
&
&
&
&
0
25ms
0
t
delta T
&
&
&
Polarity detector
&
&
≥
1
0
t
tost
OST&
≥
1
Note : R1 is measured resistive component of positive sequence impedance
Start Z5
Start Z6
Reset function
Start Z6
Polarity Reversed?
Not reversed
Reset function
Pred. & OST Trip
1
1
554
555
555
551
553
Figure 159: Out of Step logic diagram
4.4
OST APPLICATION NOTES
This product provides integrated Out-of-Step protection, which avoids the need for a separate stand alone Out-of-
Step device. This section provides guidance on how to configure Out of Step protection.
If you are going to use either of the predictive OST options (Pred. OST Trip or Pred. & OST Trip) you
must conduct detailed system studies to determine accurate settings. This is because high setting accuracy is
needed to avoid premature system splitting in the case of severe power oscillations that do not lead to pole slip
conditions.
Using the non-predictive OST Trip setting is simpler. You can can set it by knowing just the total system impedance,
Z
T
, and the system split points.
4.4.1
SETTING THE OST MODE
The OST Mode setting provides four options:
●
OST Disabled
●
Pred. OST Trip
●
OST Trip
●
Pred. & OST Trip
Setting OST Trip is the most commonly used approach when this protection is applied. OST Trip should be
used when Out-of-Step conditions are probable. If Out-of-Step conditions are detected, the OST command will be
issued to split the system at the pre-determined points. A disadvantage of the OST Trip option compared with
P543i/P545i Chapter 10 - Power Swing Functions
P54x1i-TM-EN-1 285

GE MiCOM P40 Agile Specifications

General

Brand	GE
Model	MiCOM P40 Agile
Category	Control Unit
Language	English