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Teleprotection For Distance Protection: To Achieve

This document discusses teleprotection schemes for distance protection that provide non-delayed, selective tripping along the entire length of a power line. It combines the advantages of unit protection that covers 100% of the feeder with distance protection's speed and backup protection. There are three main types of schemes: transfer trip schemes that transmit a trip signal to the other end during a fault, blocking schemes that transmit a blocking signal under normal conditions and allow tripping only for external faults, and unblocking schemes that continuously transmit a blocking signal and transmit an unblocking signal during a fault to enable tripping.

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171 views5 pages

Teleprotection For Distance Protection: To Achieve

This document discusses teleprotection schemes for distance protection that provide non-delayed, selective tripping along the entire length of a power line. It combines the advantages of unit protection that covers 100% of the feeder with distance protection's speed and backup protection. There are three main types of schemes: transfer trip schemes that transmit a trip signal to the other end during a fault, blocking schemes that transmit a blocking signal under normal conditions and allow tripping only for external faults, and unblocking schemes that continuously transmit a blocking signal and transmit an unblocking signal during a fault to enable tripping.

Uploaded by

bijoy
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PPT, PDF, TXT or read online on Scribd
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Teleprotection for Distance Protection

To achieve :

- non-delayed ( Speeding up )

- selective tripping

- on 100% of line length.

Combines the advantages of :

Unit Protection i.e, 100% of the feeder

and

Distance protection: Speed & back-up protection to adjacent feeders


Schemes

Classification based on signaling

Transfer Blocking Un-Blocking

Classification based on logic

Direct Permissive

Classification based on reach

Underreach scheme Overreach scheme


Transfer Trip Schemes

Signal is transferred to the other end during a fault to initiate tripping.

-Direct Tripping ( No conditions need to be met to effect tripping)

-Permissive Tripping ( Specific conditions to be met to effect tripping)

Underreach : Signal transmitted by the Zone which does not cover the
entire feeder length. Small time delay introduced owing
to instantaneous operation of the transmitting zone.

Overreach : Signal transmitted by the Zone which covers beyond the


entire feeder length. Instantaneous transmission of signal
Blocking scheme

Uses inverse logic ie. Signal is transferred only for external faults

Activation of forward overreaching units and absence of blocking signal


enable tripping.

Un-Blocking scheme

Uses inverse logic ie. Information is transferred only for external faults

Continuous block signal is transmitted and during fault another signal ( Un-blocking)
Is transmitted.

Activation of forward overreaching units and presence of Un-blocking signal


enable tripping.
Difference between Blocking & Unblocking Scheme

Blocking (Release) Scheme Enable


Trip

Signal is sent to the remote end during normal situation ie., for faults which are
external, so as to effectively block untoward tripping.
Absence of the signal from remote end and local pickup causes tripping.
Robust signalling system required

Enable
Unblocking (Release) Scheme Trip

Release Signal is sent to the remote end to enable remote trip in the case of fault.
Presence of signal from remote end and local pickup causes tripping.
Absence of both block and unblock signals triggers tripping logic.

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