Day 2 Transmission Line Protection

8/3/2019 Day 2 Transmission Line Protection

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TRANSMISSION LINEPROTECTION

TRANSMISSION LINEPROTECTION

20 December 2010 1Protection Courses


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TUTORIAL SCOPE8. LOAD ENCROACHMENT9. LOSS OF POTENTIAL10. UNIT PROTECTION11. PERMISSIVE UNDER REACH12. PERMISSIVE OVER REACH13. CARRIER BLOCKING14. CURRENT REVERSAL15. ZONE 1 EXTENSION


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TUTORIAL SCOPE16. WEAK IN-FEED17. SERIES COMPENSATION18. MUTUAL COMPENSATION19. AUTO RECLOSER20. STUB PROTECTION21. CCVT TRANSIENT22. DIRECTIONAL EARTH FAULT


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MHO CHARACTERISTICS

MHO


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MHO CHARACTERISTICS


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QUADRILATERAL CHARACTERISTICS

Quadrilateral


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OFFSET MHO CHARACTERISTICS


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POLARIZATION METHODS SELF POLARIZATION

Terminal faults will not cover CROSS POLARIZATION

Use other healthy phase voltages Terminal three phase fault will not cover

MEMORY POLARIZATION Covers all type of faults


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VR

VB

VY

VRB

VBY

VYR

POLARIZATION METHODS


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S/Stn 1 S/Stn 2 S/Stn 3

Time

Zone 3R

Zone 3R

Zone 3R

Zone 2

Zone 2Zone 3R

Zone 2

RelayA

RelayB

RelayC

RelayD

Zone 3F

Zone 2Zone 3

Zone 1

Zone 1

Zone 1

Zone 1

ZONES SETTING CRITERIA


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A B C

X

R

Zone 1

Zone 3Zone 2

ZONES SETTING CRITERIA

Zone 4


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SWITCH ON TO FAULT SWITCH ON TO FAULT.

Failure to remove Earth Clamps after CB Maintenance

Practically Zero Impedance in fault path.

Fault Point is at the Origin - Boundary condition for Zones 1 & 2 For a 3-Phase fault, cross-polarising will have no effect

SOTF Fault Point


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AC SOTF - Used where VT is on LINE SIDE of the CBIF Current and Voltage have been Dead for 10 SecsAND the Current Rises ABOVE 30% of Nominal

AND Voltage remains BELOW 20% of NominalTHENRemove the Time Delay from Zone 3AND

Allow tripping on Overcurrent onlyFOR200ms

DC SOTF - Used where VT is on BUSBAR SIDE of the CB

When Circuit Breaker Manual Close Handle is OperatedRemove the Time Delay from Zone 3FOR 400ms

(Longer delay allows for CB Closing time)

SOTF ALGORITHMS


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Power Swing Outer

boundary

Power Swing Inner

boundary

Transittime

PowerswinglocusZone 1

Zone 2

Zone 3

If the System

ImpedanceRemains in thePower SwingDetection Zone forlonger than thePSD Transit Time

(Nominally 50 ms)POWER SWINGALARMwill Operate

POWER SWING DETECTION & BLOCKING


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POWER SWING DETECTION & BLOCKING


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LOAD ENCROACHMENT


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LOSS OF POTENTIAL


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Zone 2Carrier

AidedTrip

S/Stn 1 S/Stn 2

Time

Zone 1 (No Operation)

Distance

Distance

Zone 1

Relay

B

Relay

C

Relay

A Signalling Channel

Zone 2Time Delayed Trip

Operation of Zone 1 sends signal to remote end

Instantaneous trip if

Zone 1 Operation

Zone 2 + Signal from Remote end

ALLOWS INSTANTANEOUS TRIPPING OVER 100% OF THE LINE LENGTH

Zone 2

SIGNALLING CHANNELREQUIRED BETWEENENDS

PERMISSIVE UNDER REACH


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Zone 2Carrier

AidedTrip

S/Stn 1 S/Stn 2

Time


Distance

Distance

Relay

B

Relay

C

Relay


Zone 2Time Delayed Trip

Instantaneous Operation of Zone 2 sends signal to remote end


Zone 1 Operation

Zone 2 + Signal from Remote end

Zone 2Zone 2 Instantaneous

Zone 1



PERMISSIVE OVER REACH


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Zone 2Carrier

AidedTrip

S/Stn 1 S/Stn 2

Time


Distance

Distance

Zone 1

Relay

B

Relay

C

Relay


Zone 4 - Blocking

Operation of Zone 4 sends blocking signal to remote end


Zone 1 Operation

Zone 2 + No blocking Signal from Remote end WITHIN the Permissive Trip Time

Zone 2



BLOCKING SCHEME


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Zone 2CarrierAidedTrip

S/Stn 1 S/Stn 2

Time


Distance

Distance

Zone 1

RelayB

RelayC

RelayA Signalling Channel

Zone 4 - Blocking(No Operation)

Operation of Zone 4 sends blocking signal to remote end


Zone 1 Operation

Zone 2 + NO BLOCKING SIGNAL from Remote End

WITHIN the Permissive Trip Time

Zone 2



BLOCKING SCHEME


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24Protection Courses

CURRENT REVERSAL

20 December 2010


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CURRENT REVERSAL


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CURRENT REVERSAL


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Relay

A

Relay

B

Relay

C

S/Stn 1 S/Stn 2

Relay

C

S/Stn 3

Time

Gives improved fault clearancetime for fault @ this position

Will trip CB @ 'A' forfault @ this position

No Signalling used between ends

Used with Auto-Recloser only

Results in More Breaker Operations

Zone 2Zone 3F

Distance

Distance

Trip

Reclose

Zone 1 Ext

Zone 1

ZONE 1 EXTENSION SCHEME


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WEAK IN FEED LOGIC


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SERIES COMPENSATION Used to increase load capacity Improve power system stability Improve load division on parallel paths Reduce transmission losses


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SERIES COMPENSATION

Voltage reversal


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COUPLINGBETWEENLONGLINESCANHAVEASIGNIFICANTEFFECTONDISTANCEPROTECTIONMEASUREMENT

ONLYAFFECTSZEROSEQUENCECOMPONENT(PPSANDNPSCOMPONENTSAREBALANCEDANDTHEREFORESUMTOZERO)

IFRELAY

NOT

COMPENSATED

FOR

EARTH

RETURN

AND

MUTUAL

EFFECTS

Z1WILLBEOVER

ESTIMATEDANDTHERELAYWILLUNDERREACH

Ia

ZMO

Fault

Ib

Double Circuit Line

MUTUAL COMPENSATION 1


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When one of the lines is out of service and earthed at both ends

Energise a Status Input SWITCH TO ALTERNATE SETTINGS group

ALTERNATE SETTING GROUP uses

Increased Earth Fault Compensation Factor to take account of the Zero

Sequence Mutual Coupling due to the parallel line

MUTUAL COMPENSATION 2


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CCVT TRANSIENT


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CCVT TRANSIENT Distance element may over reach CCVT Trans. Reduce the fundamental component of the

fault voltage results in decrease in the calculated impedance High capacitance reduced transient effect Passive Ferro-resonance reduced transient effect


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CCVT TRANSIENT


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DIRECTIONAL EARTH FAULT 1

Unrestricted Characteristic

Operates for any fault current above setting in selected direction

Detects high impedance earth faults

Operate quantity - residual current

Polarising quantity - residual voltage

X

R

Line

Angle


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DUAL DIRECTIONAL EARTH FAULT TWO Unrestricted Characteristics

Common Line Angle Setting

Different Operating Current Settings

Forward DEF

Operates on Current above FWDsetting in FORWARD direction

Reverse DEF

Operates on Current above REVsetting in REVERSE direction

X

RLine

Angle

Forward

DEF

Reverse

DEF


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Discrimination using DTL or IDMTL Time Grading (DEF Direct Trip)

OR

High Speed operation using a Signalling Channel (DEF POR)

Operation of both DEF elementsallows instantaneous tripping

If no Signalling Channel is available

OR

Signalling Channel fails

RELAY CAN OPERATE AS BACK-UPTIME GRADED OVER CURRENT

DIRECTIONAL EARTH FAULT 2

Day 2 Transmission Line Protection

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