Teleprotection function
Budapest, July 2011.
Teleprotection function
Teleprotection function
The non-unit protection functions, generally distance protection, can have two, three or even
more zones available. These are usually arranged so that the shortest zone corresponds to
an impedance slightly smaller than that of the protected section (underreach) and is normally
instantaneous in operation. Zones with longer reach settings are normally time-delayed to
achieve selectivity.
As a consequence of the underreach setting, faults near the ends of the line are cleared with
a considerable time delay. To accelerate this kind of operation, protective devices at the line
ends exchange logic signals (teleprotection). These signals can be direct trip command,
permissive or blocking signals.
In some applications even the shortest zone corresponds to an impedance larger than that of
the protected section (overreach).
As a consequence of the overreach setting, faults outside the protected line would also cause
an immediate trip command that is not selective. To prevent such unselective tripping,
protective devices at the line ends exchange blocking logic signals.
The combination of the underreach overreach settings with direct trip command, permissive
of blocking signals facilitates several standard solutions, with the aim of accelerating the trip
command while maintaining selectivity.
The teleprotection function block is pre-programmed for some of these modes of operation.
The required solution is selected by parameter setting; the user has to assign the appropriate
inputs by graphic programming.
Similarly, the user has to assign the send signal to a relay output and to transmit it to the far
end relay. The trip command is directed graphically to the appropriate input of the trip logic,
which will energize the trip coil.
Depending on the selected mode of operation, the simple binary signal sent and received via
a communication channel can have several meanings:
Direct trip command
Permissive signal
Blocking signal
To increase the reliability of operation, in this implementation of the telecommunication
function the sending end generates a signal, which can be transmitted via two different
channels.
NOTE: the type of the communication channel is not considered here. It can be
Pilot wire
Fiber optic channel
High frequency signal over transmission line
Radio or microwave
Binary communication network
Etc.
The function receives the binary signal via optically isolated inputs. It is assumed that the
signal received through the communication channel is converted to a DC binary signal
matching the binary input requirements.
For the selection of one of the standard modes of operation, the function offers two
enumerated parameters, Operation and PUTT Trip. With the parameter Operation, the
following options are available: PUTT, POTT, Dir. Comparison, Dir. Blocking, DUTT while with
the parameter PUTT Trip: with Start,with Overreach can be set.
VERSION 1.0
2/6
01.07.2011. Gyula Pka
Teleprotection function
Permissive Underreach Transfer Trip (PUTT)
The IEC standard name of this mode of operation is Permissive Underreach Protection
(PUP).
The protection system uses telecommunication, with underreach setting at each section end.
The signal is transmitted when a fault is detected by the underreach zone. Receipt of the
signal at the other end initiates tripping if other local permissive conditions are also fulfilled,
depending on parameter setting.
For trip command generation using the parameter SCH85_PUTT_EPar_ (PUTT Trip), the
following options are available:
with Start
with Overreach
Permissive Underreach Transfer Trip (PUTT) with start
The protection system uses telecommunication, with underreach setting at each section end.
The signal is transmitted when a fault is detected by the underreach zone. The signal is
prolonged by a drop-down timer. Receipt of the signal at the other end initiates tripping in the
local protection if it is in a started state.
UZSt
Rec1
Rec2
Send
Blk
NOT
CarrFail
NOT
AND
Send
OR
ZSt Fw
Blk
NOT
CarrFail
NOT
SEND
AND
Ztp
RECEIVE
Permissive Underreach Transfer Trip (PUTT) with Overreach
The protection system uses telecommunication, with underreach setting at each section end.
The signal is transmitted when a fault is detected by the underreach zone. The signal is
prolonged by a drop-down timer. Receipt of the signal at the other end initiates tripping if the
local overreaching zone detects fault.
UZSt
Rec1
Rec2
Send
Blk
NOT
CarrFail
NOT
AND
Send
SEND
VERSION 1.0
OR
OZSt
Blk
NOT
CarrFail
NOT
AND
Ztp
RECEIVE
3/6
01.07.2011. Gyula Pka
Teleprotection function
Permissive Overreach Transfer Trip (POTT)
The IEC standard name of this mode of operation is Permissive Overreach Protection (POP).
The protection system uses telecommunication, with overreach setting at each section end.
The signal is transmitted when a fault is detected by the overreach zone. This signal is
prolonged if a general trip command is generated. Receipt of the signal at the other end
permits the initiation of tripping by the local overreach zone.
OZSt
GenTr
AND
Blk
NOT
CarrFail
NOT
Rec1
Rec2
OR
Sen
d
AND
Send
OR
OZSt
Blk
NOT
CarrFail
NOT
SEND
AND
Ztp
RECEIVE
Directional comparison (Dir.Comparison)
The protection system uses telecommunication. The signal is transmitted when a fault is
detected in forward direction. This signal is prolonged if a general trip command is generated.
Receipt of the signal at the other end permits the initiation of tripping by the local protection if
it detected a fault in forward direction.
ZSt Fw
Gen Tr
AND
Blk
NOT
CarrFail
NOT
T
Dir Tr
OR
Send
AND
SEND
VERSION 1.0
Rec1
Rec2
OR
ZStFw
Blk
NOT
CarrFail
NOT
AND
RECEIVE
4/6
01.07.2011. Gyula Pka
Ztp
Teleprotection function
Blocking directional comparison (Dir.Blocking)
The IEC standard name of this mode of operation is Blocking Overreach Protection (BOP).
The protection system uses telecommunication, with overreach setting at each section end.
The blocking signal is transmitted when a reverse external fault is detected. The signal is
prolonged by a drop-down timer. For the trip command, the forward fault detection is delayed
to allow time for a blocking signal to be received from the opposite end. Receipt of the signal
at the other end blocks the initiation of tripping of the local protection. The received signal is
accepted only if the duration is longer then the parameter Min.Block Time, and the signal is
prolonged by a drop-down timer.
OZSt
T
ZSt Bw
ZSt Fw
St
Send
ZSt Fw
NOT
Blk
NOT
CarrFail
NOT
Send
AND
Rec 1
Rec 2
OR
OR
T
NOT
Ztp
AND
Min Blk
Pro Blk
Blk
NOT
CarrFail
NOT
SEND
RECEIVE
Direct underreaching transfer trip (DUTT)
The IEC standard name of this mode of operation is Intertripping Underreach Protection
(IUP). The protection system uses telecommunication, with underreach setting at each
section end. The signal is transmitted when a fault is detected by the underreach zone.
Receipt of the signal at the other end initiates tripping, independent of the state of the local
protection.
UZSt
T
Send
Blk
NOT
CarrFail
NOT
AND
Send
SEND
VERSION 1.0
Rec 1
Rec 2
OR
Blk
NOT
CarrFail
NOT
T
Dir Tr
AND
Ztp
RECEIVE
5/6
01.07.2011. Gyula Pka
Teleprotection function
Technical data
Function
Operate time accuracy
Accuracy
5% or 15 ms, whichever is greater
Parameters
Enumerated parameters
Parameter name
Title
Selection range
Parameter for teleprotection type selection:
Off, PUTT, POTT, Dir. comparison,
SCH85_Op_EPar_
Operation
Dir. blocking, DUTT
Parameter for PUTT type selection:
PUTT
SCH85_PUTT_EPar_
with Start, with Overreach
Trip
Default
Off
with Overreach
Timer parameters
Parameter name
Title
Unit
Send signal prolong time:
SCH85_Send_TPar_ Send Prolong time
ms
Received direct trip delay time for DUTT:
Direct Trip delay
SCH85_DirTr_TPar_
ms
DUTT
Forward fault detection delaying for Dir. Blocking:
SCH85_St_TPar_
Z Start delay (block)
ms
Duration limit for Dir. Blocking:
SCH85_MinBlk_TPar
Min. Block time
ms
_
Prolong duration for Dir. Blocking:
SCH85_ProBlk_TPar
Prolong Block time
ms
_
Min
Max
Step
Default
10000
10
10000
10
10000
10
10000
10
10000
10
Binary output status signals
Binary output status signals
SCH85_Ztp_GrI_
Signal title
Z Teleprot. Trip
SCH85_Send_GrI_
Send signal
Explanation
Teleprotection trip command
Teleprotection signal to be
transmitted to the far end
Binary input status signals
The binary input status signals are the results of logic equations graphically edited by the
user.
Binary input signals
SCH85_Blk_GrO_
Signal title
Block
SCH85_CarFail_GrO_
Carrier fail
SCH85_Rec1_GrO_
SCH85_Rec2_GrO_
SCH85_ZStFw_GrO_
SCH85_UZSt_GrO_
SCH85_OZSt_GrO_
SCH85_GenTr_GrO_
SCH85_ZStBw_GrO_
Receive opp.1
Receive opp.2
Z Gen.start Fw
Z Underreach Start
Z Overreach Start
General Trip
Z Gen.start Bw
VERSION 1.0
6/6
Explanation
Blocking signal
Signal indicating the failure of the
communication channel
Signal 1 received from the opposite end
Signal 2 received from the opposite end
Protection start in forward direction
Start of the underreaching zone (e.g. Z1)
Start of the overreaching zone (e.g. Z2)
General protection trip
Protection start in backward direction
01.07.2011. Gyula Pka
