Alstom MiCOM P846, Техническое руководство

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P846/EN FD/D Firmware Design
(FD) 9-18
MiCOM P846
i.e.:
Phase advanced vector Vp
= Vp (cos(s) + jsin(s)) * (sin(d) + jcos(d))
= Vp [- sin(s-d) + jcos(s-d)]
Phase advanced vector
Ι
pZr
=
Ι
pZr (cos (e) + jsin (e)) * (sin (d) + jcos (d))
=
Ι
pZr [- sin(e-d) + jcos(e-d)]
therefore from equation 1
m = Vp ÷ (
Ι
p * Zr) at
Ι
f = 0
= Vpsin(s-d) / (
Ι
pZr * sin(e-d))
where
d = angle of fault current
Ι
f
s = angle of Vp
e = angle of
Ι
pZr
Thus the relay evaluates m which is the fault location as a percentage of the fault locator line
impedance setting and then calculates the output fault location by multiplying this by the line
length setting. When calculated, the fault location can be found in the fault record under the
"VIEW RECORDS" column in the Fault Location
cells. Distance to fault is available in
kilometers, miles, impedance or percentage of line length.
1.5.4.3 Data acquisition and buffer processing
The fault locator stores the sampled data within a 12 cycle cyclic buffer at a resolution of 24
samples per cycle. When the fault recorder is triggered the data in the buffer is frozen such
that the buffer contains 6 cycles of pre-trigger data and 6 cycles of post-trigger data. Fault
calculation commences shortly after this trigger point.
FD
The trigger for the fault locator is user selectable via the programmable scheme logic.
The fault locator can store data for up to four faults. This ensures that fault location can be
calculated for all shots on a typical multiple re-close sequence.
1.6 Self testing & diagnostics
The relay includes a number of self-monitoring functions to check the operation of its
hardware and software when it is in service. These are included so that if an error or fault
occurs within the relay’s hardware or software, the relay is able to detect and report the
problem and attempt to resolve it by performing a re-boot. This involves the relay being out
of service for a short period of time which is indicated by the ‘Healthy’ LED on the front of the
relay being extinguished and the watchdog contact at the rear operating. If the restart fails to
resolve the problem, then the relay will take itself permanently out of service. Again this will
be indicated by the LED and watchdog contact.
If a problem is detected by the self-monitoring functions, the relay attempts to store a
maintenance record in battery backed-up SRAM to allow the nature of the problem to be
notified to the user.
The self-monitoring is implemented in two stages: firstly a thorough diagnostic check which
is performed when the relay is booted-up, e.g. at power-on, and secondly a continuous
self-checking operation which checks the operation of the relay’s critical functions whilst it is
in service.