Basic Protection Technology

8/20/2019 Basic Protection Technology

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Power Transmission and Distribution

No. 1 withEnergy Automation

Energy Automation Badiya Page 1

Power System Structure

Generation Transmission / Sub transmission Distribution

Extra High Voltage 7! "V

#$$ "V

%%$ "V

High Voltage 1&% "V11$ "V

"V

'edium Voltage && "V

%% "V

11 "V

'edium %# "V

Voltage %1 "V

1! "V

1&() "V

The *ur*ose o+ an ele,tri,al *o-er system is to generate and su**ly ele,tri,al energy to,onsumers( The system should be designed and managed to deli.er this energy to the

utilisation *oints -ith both reliability and e,onomy(

The *ur*ose o+ an ele,tri,al *o-er system is to generate and su**ly ele,tri,al energy to,onsumers( The system should be designed and managed to deli.er this energy to the

utilisation *oints -ith both reliability and e,onomy(

'any items o+ eui*ment are .ery ex*ensi.e0 and so the ,om*lete *o-er system re*resents a.ery large ,a*ital in.estment(

(

'any items o+ eui*ment are .ery ex*ensi.e0 and so the ,om*lete *o-er system re*resents a.ery large ,a*ital in.estment(

(


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Energy Automation Badiya Page %

System Disturbances

Short ir,uits in earthed systems

Symmetri,al 2& *hase3

Phase to Phase 2and Earth3

Phase to Earth

Earth 4aults in non e++e,ti.elyearthed systems

5.erload onditions

6nder+reuen,y/6nder.oltage

5.er.oltage


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Energy Automation Badiya Page &

Prote,ti.e elaying is the most im*ortant +eature o+

*o-er system design aimed at minimising the

damage to eui*ment and interru*tion to ser.i,e in

the e.ent o+ +aults( 8t is there+ore a ,o9+a,tor

among other +a,tors resorted to im*ro.e reliability

o+ *o-er system(

Protective Relaying

Role of Protection


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Energy Automation Badiya Page #

The Purose of Protection

!ut it can"#imit the damage caused by shortcircuits

$hile"

Prote,ting *eo*le and *lant +romdamage

Sele,ti.ely ,learing +aults inmilise,onds

Prote,ting *lant +rom o.erload

,onditions

The rotection can not revent system faults%

Po-er system must o*erate in a sa+e manner at all times(


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Energy Automation Badiya Page !

&auses and Probability of System Disturbances

Causes

Operator Mistakes

Pollution/Condensation

Equipment failures, e.g. P.T.'s, Isolators

Transient Overvoltages

Probability

System faults (220/400 kV): 3p.a. and 100 km

10-20 kV metal clad switchgear:10-3p.a. and feeder

GIS switchgear: 5-10-2p.a. and bus

outdoor switchgear: 110/132 kV7*10

-2

p.a. and bus 220/275 kV 10-1p.a. and bus 400 kV 2*10-1p.a. and bus


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Energy Automation Badiya Page

Sin,e *rote,ti.e relaying ,omes into a,tion at the time o+

eui*ment distress0 a ,ertain sa+eguard is ne,essary inthe unli"ely e.ent o+ its +ailure to a,t at the hour o+ need(

Hen,e0 t-o grou*s o+ *rote,ti.e s,hemes are generally

em*loyed 9

a3 Primary Prote,tion

b3 Ba,"9u* Prote,tion

Primary Prote,tion is the +irst line o+ de+ense0 -hereasba,"9u* relaying ta"es o.er the *rote,tion o+ eui*ment0

should the *rimary *rote,tion +ail(

Princiles of Relaying


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The Primary Prote,tion has +ollo-ing ,hara,teristi, +eatures 9

1( 8t has al-ays a de+ined :one o+ o*eration(

%( 8t should o*erate be+ore any ba,"9u* *rote,tion

,ould o*erate0 there+ore0 it should be +aster in

o*eration(

&( 8t should be able to ,om*letely isolate the +ault

+rom all the ,urrent +eeding sour,es(

#( 8t should be stable +or all o*erating ,onditions(

Primary Protection


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Energy Automation Badiya Page )

1( Ba,"9u* *rote,tion should *ro.ide su++i,ient time

+or the *rimary *rote,tion to *er+orm its duty(

%( Ba,"9u* *rote,tion ,o.ers a -ider :one o+

*rote,tion( There+ore0 there is al-ays a *ossibility

o+ large s,ale disturban,e0 -hen ba,"9u* relays

o*erate(

&( 6nder *rimary *rote,tion +ailure0 se.eral ba,"9u*

relays may o*erate +or ,om*lete isolation o+ +ault(

!ac'(u Protection

P T i i d Di t ib ti


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Energy Automation Badiya Page ;

Primary *rote,tions +ailure ,ould be due to any o+ the+ollo-ing reasons 9

1( urrent or Potential Trans+ormer +ailure

%(


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Energy Automation Badiya Page 1$

Protection &oncet

The system is only as strong as the wea'est lin'*

D+STAN&E RE#A,

Circuit BreakerCT / VT

Protection Battery

&abling



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!asic Protection

Re-uirements

Reliability deendability availability/high deendability 0 low ris' of failure to tri

Security stable for all oerating conditions %

high security 0 low ris' of over(tri

Seed high seed minimies damage

high seed reduces stability roblems

Selectivity tri the minimum number of circuit brea'ers

Sensitivity notice smallest fault value



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Energy Automation Badiya Page 1%

2ones of Protection

To limit the e3tent of the ower system that is disconnected when a fault

occurs% rotection is arranged in ones

2ones of rotection should overla% so that no art of the ower system is left

unrotected

#ocation of the &T connection to the rotection usually defines the one

4nit tye rotections have clear ones reach e.g Diff. Relay% RE) relay 2one reach deends on measurement of the system -uantities e.g 5& % E)%

distance relays . The start will be defined but the e3tent or 6reach7/ is sub8ect

to variation% owing to changes in system conditions and measurement errors.



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Energy Automation Badiya Page 1&

Protection ( 5ne 5ut of Two Princile

System1

TripCoil1

Battery 1

↑

↑

System2

TripCoil2

Battery 2



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Energy Automation Badiya Page 1#

Redundancy &oncet of D& &ircuits

Battery 1Battery 2

Main Protection

87T

TR

TC 1

L-

Back-up Protection

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TR

TC 2

Busbar Protection

87BB

TR

BF

L-

Trip remote infeed



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Energy Automation Badiya Page 1!

)actors that influence fault current magnitude

9

> Short circuit ower of the infeed> :oltage level> #ine imedance> )ault resistance arc/> Treatment of star oint

+nfeed &onsumer#ine

Estimate of short circuit currents"

;edium :oltage 1< ': uto =0 +#ma3

E3tra ?igh :oltage @@


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Earth faults" Star(oint configuration

R L

earthed system Peterson Coil isolated neutral• Earth fault =short circuit is recognised by normal over-current protection.• With low impedance earthing the residual current detection must be more sensitive.

• Earth faults = no short circuit• Supply is not disrupted• Earth fault must be alarmed and removed as fast as possible• Earth fault location is achieved with wattmetric earth fault detection



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Protection &riterion ( &urrent

The o.er,urrent ,ondition is e.aluated 8? Suitable +or@

Additional ,riterion 9 Time

to ensure selectivity/Prote,tion@ 4uses in.erse time *rote,tion 28D'T3 de+inite time *rote,tion 2DT3

+

+S&min+#ma3

+>



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Energy Automation Badiya Page 1)

Protection &riterion ( &urrent Difference

Evaluation of node +1 +@ += ... +n 0


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Energy Automation Badiya Page 1;

Protection &riterion ( +medance

)rom the voltage and current signals theimedance is calculated The imedance is roortional to the fault distance&haracteristic"

Additional criterion ( Time Re-uired for selectivity and bac'(u rotection/

Protection";ultile stage distance rotection

R

F

2G



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Energy Automation Badiya Page %$

;easured signals and time grading rincile

Protected ob8ect

Protectiondevice

t

l

t1

t@

t=

21A ! 2@

A !

Exam*le distan,e *rote,tion



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Energy Automation Badiya Page %1

&omarison Protection Princile

Protected ob8ect

A !

Protectiondevice

Protectiondevice

Protection

device

communication

momentary .alues/binary de,isions

t

A B



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Energy Automation Badiya Page %%

Tyical Distance 2one &haracteristics

;?5(circle combined circle(

and straight line

characteristic

olarised;?5(circle

olygonal triing

characteristic

-uadrilateral/

A

S

S

external+ault

internal+ault

C

7

ϕΘ

C

7

S D $

S small

S large

S

74

<

starting :one

one &

one %

one 1

C

7

settable ar, ,om*ensationCC A

<7


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Energy Automation Badiya Page %&

4urther Ty*i,al Prote,tion riteria

urrent in,rease6nder and o.er .oltageDire,tional ,om*arisonPhase ,om*arisonPo-er dire,tion

Phase angle5.er and under +reuen,y4reuen,y gradientHarmoni,sS*e,ial ,riteria in ma,hine *rote,tion



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Energy Automation Badiya Page %#

Ty*i,al Prote,ted 5be,ts

Generators

Trans+ormers

Busbars


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Energy Automation Badiya Page %!

Redundancy &oncets

Line Protection

LP1

LP2

≥1

1 out of 2 principle

trip line

Busbar Protection

Section1

&

2 out of 2 principle

trip section 1

Section2

Check

Zone

& trip section 2

Transformer Protection

Relay1

≥1

1 out of n principle

trip transformer

Relayn

.

.

.



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Energy Automation Badiya Page %

Stability #imits in Transmission System

<

1<

@<

=<

H<

B<

I<

J<

1=


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Energy Automation Badiya Page %7

)ailure Rate of Redundant Systems

<


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Energy Automation Badiya Page %)

$hy Digital ProtectionM

+ntegration of the rotection functions for one feeder"

)eeder rotection device

E3amle" overhead line of e3tra high voltage

Distance rotection with +>> or uGi>(e3itation

Three(ole reclosure Directional earth fault detection

)ault location

Event log

)ault recording



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Energy Automation Badiya Page %;

$hy Digital ProtectionM

Self-supervision

Raising of the availability

Plausibility control of the inut values

Suervision of the ad(conversion

+nternal testing of the comuter systems watch(dog/

Suervision of the memory chis

Testing the tri(relay(coil



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Energy Automation Badiya Page &$

&ontact Terms

&ontacts rovide electrical oututs for triing and remote

indication uroses

Self-reset

The ,onta,ts remain in the o*erated ,ondition only -hile the ,ontrolling uantity is a**lied0

returning to their original ,ondition -hen it is remo.ed(

Hand or electrical reset

These ,onta,ts remain in the o*erated ,ondition a+ter the ,ontrolling uantity is remo.ed( They

,an be reset either by hand or ele,tri,ally by an auxiliary ele,tromagneti, element

A 'make' contact is one that ,loses -hen the relay *i,"s u*

A break contact is one that is ,losed -hen the relay is de9energised and o*ens -hen the relay *i,"s u*(

Basic Protection Technology

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