Ormazabal ekor.rps, Общее руководство по инструкции

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IG-150-EN version 04; 03/10/16
110
Protection functions. Description and settings General instructions
ekor.rps
Pre-fault and post-fault filtering
The distance calculation algorithm uses the basic
components of the voltage and current waves. The filtering
extracts the said components from the signals stored at the
start-up moment.
The collected signal is processed using a digital filter that
provides the basic voltage and current components. For
this stage, a cosine filter is used.
The filtering is adapted to the fault cycle number it finds,
up to a maximum of 5 cycles and a minimum of 1 cycle. The
transition is also detected in evolutive faults, limiting the
cycle number to the fist type that appears.
Determination of fault type
Before launching the distance calculation algorithm, from
the pre-fault and fault measurements calculated in the
preceding step, it is necessary to define the kind of fault
that has occurred.
The locator includes an algorithm that determines what
phases were affected by the fault. The algorithm used
is based on the known Girgis method for distance relays.
This procedure, which analyses the various magnitudes of
the change between the pre-fault situation and the post-
fault situation in the basic component of the currents, has
demonstrated an enviable accuracy in its results.
Distance Calculation
The distance calculation algorithm developed for the single
line has been designed for a line topology such as the
following figure.
Vrele
Irele
Figure 4.42. Line topology
When a fault occurs on one of the lines corresponding to
our relay, the information collected by the locator, located
at one of the ends of the same, is reduced to the voltage
and current values.
The necessary equations for completely determining
the system will be obtained from the situation existing
at the instant immediately before the fault and from the
fault situation itself. The application of the principle of
superposing the models in the generators and a suitable
mathematical development lead to a system of equations.
The use of the expressions obtained allows calculating the
distance to the fault. In order to establish the interactive
method that allows calculating the distance, the three
different kinds of faults must be considered as mentioned
in the preceding point.