Areva MiCOM P441, Техническое руководство

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Application Notes P44x/EN AP/E33
MiCOM P441/P442 & P444 Page 41/220
2.9 Channel-aided distance schemes
The following channel aided distance tripping schemes are available when the Standard
program mode is selected:
•
Permissive Underreach Transfer Trip Schemes PUP Z2 and PUP Fwd;
•
Permissive Overreach Transfer Trip Schemes POP Z2 and POP Z1;
•
Weak infeed logic to supplement permissive overreach schemes;
•
Unblocking logic to supplement permissive schemes;
•
Blocking Schemes BOP Z2 and BOP Z1;
•
Current reversal guard logic to prevent maloperation of any overreaching zone used in
a channel aided scheme, when fault clearance is in progress on the parallel circuit of a
double circuit line.
2.9.1 Permissive Underreach Transfer Trip Schemes PUP Z2 and PUP Fwd
To provide fast fault clearance for all faults, both transient and permanent, along the length
of the protected circuit, it is necessary to use a signal aided tripping scheme. The simplest
of these is the permissive underreach protection scheme (PUP), of which two variants are
offered in the P441, P442 and P444 relays. The channel for a PUP scheme is keyed by
operation of the underreaching zone 1 elements of the relay. If the remote relay has
detected a forward fault upon receipt of this signal, the relay will operate with no additional
delay. Faults in the last 20% of the protected line are therefore cleared with no intentional
time delay.
Listed below are some of the main features/requirements for a permissive underreaching
scheme:
•
Only a simplex signalling channel is required.
•
The scheme has a high degree of security since the signalling channel is only keyed
for faults within the protected line.
•
If the remote terminal of a line is open then faults in the remote 20% of the line will be
cleared via the zone 2 time delay of the local relay.
•
If there is a weak or zero infeed from the remote line end, (ie. current below the relay
sensitivity), then faults in the remote 20% of the line will be cleared via the zone 2 time
delay of the local relay.
•
If the signalling channel fails, Basic distance scheme tripping will be available.
P3054XXa
ZL
Z1A
A B
Z1B
Z2A
Z2B
FIGURE 17 - ZONE 1 AND 2 REACHES FOR PERMISSIVE UNDERREACH SCHEMES