Areva MiCOM P441 - P44 X;En AD;E44

Update Documentation P44x/EN AD/E44
MiCOM P441, P442 & P444 Page 21/82
4. DISTANCE ALGORITHMS
The "Deltas" algorithms have priority over the "Conventional" algorithms if they have been
started first. The latter are actuated only if "Deltas" algorithms have not been able to clear
the fault within two cycles of its detection.
Since version C1.x no priority is managed any more. The fastest algorithm will give
the immediate directional decision.
4.1 Distance and Resistance Measurement
R
fault
and D
fault
are computed for every sample (24 samples per cycle).
NOTA: See also in §4.3.1 of that chapter the Rn and Dn (Xn) conditions of
convergence.
4.2 "Deltas" Algorithms
The patented high-speed algorithm has been proven with 10 years of service at all voltage
levels from MV to EHV networks. The P440 relay has ultimate reliability of phase selection
and directional decision far superior to standard distance techniques using superimposed
algorithms. These algorithms or delta algorithms are based on transient components and
they are used for the following functions which are computed in parallel.
4.2.1 Network Status Monitoring
…/…
• Power System Frequency is being measured and tracked (48 samples per cycle at 50
or 60Hz).
4.3 "Conventional" Algorithms
NOTA: The distance measurement of the fault is taken on the loop selected
by the "Deltas" or "conventional" phase selection algorithms. This
measurement uses the fault values which are computed by Gauss
Seidel method.
4.3.1 Convergence Analysis
This analysis is based on the measurements of distance and resistance of the fault. These
measurements are taken on each single-phase and two-phase loops (15 loops in total).
4.3.5 Directional Decision during SOTF/TOR (Switch On To Fault/Trip On Reclose)
…/…
If a stored voltage does not exist (SOTF) when one or more loops are convergent within the
start-up characteristic, the directional is forced forward and the trip is instantaneous (if
“SOTF All Zones “ is set or according to the zone location if SOTF Zone 2, etc. is set). If the
settable switch on to fault current threshold I>3 is exceeded on reclosure, the relay
instantaneously trips three-phase (No timer I>3 is applied – see also the chapter AP in
§2.12).
…/…
Other modes can be selected to trip selectively by SOFT or TOR according to the fault
location (SOTF Zone 1, SOTF Zone 2, etc., TOR Zone 1, TOR Zone 2, etc. depending from
the software version - from A3.1 available).There are 13 bits of settings in TOR/SOTF
logic.