auto-reclosure; synchro-check & voltage check

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Technology and SolutionsProtection and Substation Automation

Topic:

REL316*4 Auto- Reclosure; Synchro- Check & Voltage Check

BASICSBASICS

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REL316*4 Auto Reclosure; Synchro- & Voltage Check

Objectives

Auto Reclosure (79)Rules / FactsImportant SettingsSupervision of the breaker (CB memory)the four AR cyclesFunction of the operating timeExamplesSubstations with single busbar or multiple busbar1 1/2 breaker schemeMaser / Follower schemeLine Protection Interfaces

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REL316*4 Auto Reclosure; Synchro- & Voltage Check

Objectives

Synchro Check (25) & Voltage Check (27/59)Auto Reclosure interfaces3-pole tripping with 3-pole AR1-pole tripping with 1-pole AROperating ModesSynchronism MonitoringApplication ExampleVoltage Selection

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REL316*4 Auto Reclosure (79)

Application

SYSTEM

SYSTEM

SYSTEM

TRIP LP TRIP LP

AR Close CB AR Close CB

Load

SYSTEM

Load

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REL316*4 79 - Rules / Facts

On several auto-reclosing cycle, only the first cycle can be single pole tripping with fast auto-reclosing Following auto-reclosing cycles must be three phase tripping and reclosing

The line protection must provide single phase trip for the first fault, following faults must be tripped three phase

The closing command always goes to all three phases

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No synchro check is needed for fast single phasereclosing (Sychro-check by-pass)The system will not loose synchronity: 3 of 4 conductors (2 phases and ground) are still in serviceDuring the pause time the line still transmits more than 50% of the maximum power

If AR is not ready for a single cycle, the tripping circuit must be prepared or switched to 3-phase trippingReasons for AR not ready:

- AR blocked or switched off- AR blocked with t inhibit after reclosing (CB recovery time)- Fast AR dead time expired- No 1- pole AR permitted

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During the 1-pole dead time (one pole from the breaker is open) all other functions who react on unsymmetry and have a shorter tripping time then t-dead-1P-setting must be blockedExample:

- Directional earth fault with tripping scheme POTT- Pole discrepancy protection

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REL316*4 79 - Important Settings

1-pole dead time One pole opens and closes after t-dead -1P (t dead 1P) Typical dead time: 0.3 – 0.5 s in high voltage

systems3-pole dead time All 3 pole open and close after t-dead-3P (t dead 3P) Typical dead time: 0.5 s – sev. minutesOperating time Prevents an AR for a long during fault (t oper) (eg. in the 2nd zone) Discrimination time Decision about 1-pole AR, 3 pole AR or (t discrim.1P, definitive trip after evolving fault t discrim.3P)Blocking time Prolongation of the AR blocking after a manual(t AR Block) close command or after close command from

the control system

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REL316*4 79 - Important Settings

Inhibit time Blocking of the AR for 5 ….. 180 s after an(t inhibit) unsuccessful AR attempt.t inhibit is also called

recovery time. The breaker needs time to be ready for a new AR cycle

Close pulse duration Must be long enough to make sure the breaker(t close) closes properly. The close pulse is reset direct

after an unsuccessful AR attempt.

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REL316*4 79 - Supervision of the breaker (CB memory)

Breaker position: Open circuit breaker blocks the AR device. (CB open) During a running AR cycle the position of the

breaker is not interrogated. This prevents underall circumstances an AR for a switched off CB

Close open The breaker is able to switch on to a fault and to(CO ready) open again. This information is interrogated

direct before re-closing Open-Close-Open The breaker is able to do a complete AR cycle(CB ready) This input is not interrogated during a running

AR cycle.

If the AR function operates two breakers the supervision signals are needed from both breakers.

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REL316*4 79 – four AR cycles

Why several AR cycles?

First AR: With the opening of the breaker the voltage whichsupplies the arc is switched off ⇒ the arc will extinguishThe dead time is set as short as possible. So the line canbe back in normal service as fast as possible.

Second AR: If the arc is not extinguished with the first AR attempt (tree, bamboo) a second attempt with a longer dead timewill be started (2nd and 3rd attempt are 3-phase cycles)

Third AR: This attempt is just an automatic voltage checkOne side will be switched on. An immediate trip occurs if the fault is still present. The opposite station will onlyreclose if the line was successful energized from the ownstation (Synchro- & V - Check)

Fourth AR: normally not applied in high voltage systems

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REL316*4 79 - Function of the operating time t-oper

Supervision of the fault duration is important in distance protection

Fault duration < operating timeExample: Trip in zone 1 initates an

AR cycle

Fault duration > operating timeExample: Trip in a higher zone stops the a

fast AR cycle

Tripping

Discrimination time

StartingStartingTripping

Operating timeDiscrimination time

Dead timeOn pulse

Definitive tript dead 1PQ0 Ph R

Q0 Ph SQ0 Ph T

t dead 3P Normal setting: t-oper < t2 of distance protectionThe operating time prevents AR for faults in higherzones ⇒ faults outside of the own line.Q0 Ph R

Q0 Ph SQ0 Ph T

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REL316*4 79 - Examples

AR Mode: fast AR 1 / 3 - pole Fault:: 1- phase FaultExample: - fast AR successful

Starting 1-phaseTripping 1-pole

Discrimination time

Dead time fast AR 1-pole, On - pulse

Q0 Phase R

Q0 Phase SQ0 Phase T

fast AR 1-pole

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REL316*4 79 - ExamplesAR Mode: fast AR 1 / 3 - pole and slow AR Fault: 1- phase faultExample: - fast AR not successful, - slow AR successful


Discrimination time 1-pole

Dead time fast AR 1-pole,


On-pulse, interrupted with second tripping


Dead time slow AR

Q0 Phase R


LAR

fast AR 1-pole

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REL316*4 79 - ExamplesAR Mode:fast AR 1 / 3 - pole, followed by a long dead time Fault: 1- phase faultExample: - fast AR not successful; - slow AR not successful


Definitive tripping

StartingTripping 3-pole


Discrimination time 1-pole On-pulse, interrupted with second tripping

Dead time 1-pole,


Dead time 3-pole

Q0 Phase RQ0 Phase SQ0 Phase T

fast AR 1-pole slow AR

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REL316*4 79 - ExamplesMode: fast AR 1 / 3 - pole and slow AR Fault: 1- phase faultExample: - Evolving fault before expiring of discrimination time

- fast AR not successful, slow AR successful



On-pulse, interrupted with tripping

Dead time 1-pole, interrupted with 2nd fault before expiring of 3-pole discrimination time

Q0 Phase R


Starting 1-phase(other phase)Tripping 3-pole


Dead time fast AR 3-pole



fast AR 1-poleinterrupted

fast AR 3-pole Slow AR

Dead time slow AR

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REL316*4 79 - ExamplesAR mode: fast AR 1 / 3 - pole and slow AR Fault: 1- phase faultExample: - Evolving fault after expiring of discrimination time of fast AR

- Definitive tripping



Dead time 1-pole, interrupted with 2ten fault after expiring of 3-pole discrimination time

Q0 Phase R


fast AR 1-poleinterrupted

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REL316*4 79 - Substations with single busbar or multiple busbar

Trip 2

Main 1

Main 2

AR

Trip 1 Close

3 3

Main 1

Main 2AR

Trip 1 Close

3 3

Trip 2

Standard - solution

“Cheap” - solution

Bus I

Bus II

Main 1 Main 2

AR

Main 1 Main 2

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REL316*4 79 - 1 1/2 breaker scheme

AR AR

AR

Main 1 Main 2 Main 1 Main 2

AR

Bus A

AR ARQ0 ABus A - CB

ARQ0 CCenter - CB

“Diameter”

All breakers are closedduring normal service

AR ARQ0 BBus B - CB

Bus B

Each CB next to a lineneeds an AR function.

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REL316*4 79 - Master / Follower scheme

1 1/2 breaker scheme

The Master re-closes after the set dead timeAR AQ0 A CB image

LineM

Q0 C The Follower re-closes only after successful re-closing of the Master.

In case the master is not ready for an AR-cycle a signal will be send to the follower.The follower will now re-close in the set dead time.

AR CCB image

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REL316*4 79 – Line Protection Interfaces

RE.316*4

HEST 965 010 C

Start

Trip CBTrip CB 3P

Trip 3-Pol

ZExtension

CondBlkAR

Start RST

Trip CBTrip CB 3P

1PolAR

ZExtensionAR

Start SOTF

< Z Auto-reclosurefunction

CB

open

CB

read

y

CO

read

y

Clo

s eC

B

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REL316*4 25; 27/59 – Auto Reclosure Interfaces

2527/59

the Auto Reclosure is able to send a closing command if the Permit to close Signal is active

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REL316*4 27/59 – Voltage Check

The Voltage Check is required to detect if

the Bus / Line is

Live or Dead

!!!

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REL316*4 27/59 - 3-pole tripping with 3-pole AR

Check of only one phase to phase voltage for the busbar and the line is enough

Q0

Synchro- & voltage-check

V Bus bar VLine

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REL316*4 27/59 - 1-pole tripping with 1-pole AR

On the busbar the check of one phase to phase voltage is enoughOn the line the check of all three phase to ground voltage is recommended

Q0

Synchro- & Voltage-check

Vbus bar vLine

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REL316*4 25; 27/59 – Operating Modes

Selectable Operating Modes

(bus dead AND line dead)

the Permit to close Signal is active, if the Conditions are fulfiled

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REL316*4 25 – Synchro Check

The Synchro Check is required to detect if in case of a

Live Bus & Live Line

the grid is synchronized or not

!!!

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REL316*4 25 – Synchronism Monitoring

∆V

∆ϕ

VLine

ωBusbar ωLine

fBusbar = ωBusbar /2 πfLine = ωLine /2 π

∆f = fBusbar - fLine = fSchlupf < 0.10 Hz

VLine > 80% Un

VBusbar > 80% Un

SETTINGS

VBusbar

∆V < 20% Un

∆ϕ < 15°

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REL316*4 25 – Application Example

Feeder Connected to a double busbar

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REL316*4 25 – Voltage Selection

• Only one phase to phase voltage is used for the synchro-check

Reasons:

• A three phase measuring is not needed because the synchro-check is only needed for 3-phase faults

• For 1-phase AR the synchro-check is bypassed

• Phase to ground voltage should not be used. The natural zero sequence voltage disturbs in the medium voltage system the sychro-check measuring

auto-reclosure; synchro-check & voltage check

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