Summary - GE MiCOM P40 Agile Technical Manual

P14D
Transient directionality is obtained by using the instantaneous power direction of the fault component. The
instantaneous power is calculated directly from the samples of the fault component. In Transient situations, this is
a more accurate method than using phasor based power calculations .
The fault component circuit is used for analysis. The source is the fault itself. The capacitive branch produces the
reactive power while the inductance branch absorbs the reactive power. The resistance branch absorbs the active
power. The active power is from the source. The reactive power from the source balances the total consumption of
the reactive power by the other part of the circuit.
Resistor in Neutral
Faulty Line
P Rev
Q Fwd
Generally, the reactive power is more distinctive, since the distributed capacitance is often greater than the
distributed conductance. Therefore, in resistance-grounded or isolated systems, the reactive power direction is
used for transient direction detection.
In Peterson coil grounded systems, the active power direction is used to detect the direction because the Peterson
coil distorts the reactive power flow.
The output of the direction detection function (DIR) are flags indicating the fault direction: FA DIR Forward and FA
DIR Reverse.
These flags are set if the algorithm is in the Start stage and the criteria have been met. The FA function uses the
flag status to determine whether it is a forward fault or a reverse fault. An alarm can also be set to indicate the
faulted line. When counting a spike into the FA function's counter, the FA first refers to the direction flag. Only
spikes with forward direction (Forward transient) are counted for fault evaluation.
18.1.4

SUMMARY

The type of High Impedance Fault detection solution should be selected according to the different system
grounding conditions. The solution consists of two major algorithms and a facility algorithm that forms a matrix to
cover these different conditions.
CHA detects situations where there is a continuous earth fault harmonic. CHA should only be used for directly
grounded or low resistance grounded system.
FA detects intermittent faults where the fault current is changing between conducting and non-conducting. This
can be used in any system grounding conditions. However, a continuous fault will only be detected as a steady
event. The solution matrix is as follows:
FA+DIR(Active P)
FA+DIR(Reactive Q)
FA (non DIR)
CHA
Recommended Solution
P14D-TM-EN-8
Healthy Line Faulty Line
Fwd Rev
Rev -
Solid
Applicable Applicable
Applicable Recommended
Recommended Not applicable
Recommended Recommended
CHA+FA CHA+FA+DIR(Q)
Peterson Coil in Neutral
Healthy Line
Fwd
-
Resistor
Recommended
Not applicable
Not applicable
Not applicable
FA+DIR(P)
Chapter 6 - Current Protection Functions
Isolated
Faulty Line Healthy Line
Rev Fwd
Fwd Rev
Peterson Coil
Applicable
Recommended
Not applicable
Not applicable
FA+DIR(Q)
Isolated
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