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Copyright © CFE and SEL 2014

CFE Generator Protection

Guidelines for Setting 40 and 64GEleents !ased on Siulations

and Field E"perience

Mauricio Sosa-AguiluzComisión Federal de Electricidad

Armando Guzmán and Jean LeónSchweitzer Engineering Laboratories, Inc.



CFE Po#er Plants $re %i&erse'nstalled !ase Consists of 4(1 Generators



0 50 100 150 200

–100

–50

0

50

100

150

Q ( M

A ! "

# (M$"

!o%or &urren% Limi%

Capa)ility Cur&e %eterines Safe

Generator *perating +egion

S%a%or 'nd-&oreea%ing Limi%

Arma%ure

&urren% Limi%



Lea,age Flu" Causes Stator

End-Core .eating



%irect $ir-Cooled /ur)ogenerator End



/#o-one Loss-of-Field Protection

ith %irectional Eleent Super&ision



/#o-one Loss-of-Field Protection

ith %irectional Eleent Super&ision

)'''



0 20 *0 +0 ,0 100

–+0

–*0

–20

0

20

*0

+0

,0

M$

M A !

*riginal CFE Guide +ecoendation

3atch one 2 ith Capa)ility Cur&e

&aa.ili%/ &ure

(#1Q1"

(#2Q2"

&'



Set one 2 to 3atch

Stator End-Core .eating Liit

( )

( )

− + =

− −

2 22

2 2

Q2 Q1 #2 &3!4iame%er

3!Q1 Q1 Q2 #2 Q2

6

Q2

Angle a%an #2

= ÷

( )−=

+ −2

2

2

Q2 Q1 &3!788se%

3!#2 Q2 Q1 Q2

6



one 2 3atches Stator End-Core

.eating Liit

–20 –10 0 10 20 90

–*0

–90

–20

–10

0

10

20

90

!eal (secondar/ o:ms"

) m a g

i n a r / ( s e c o n d a r / o : m s "

&aa.ili%/ &ure

;one 2

eal%:/ 7era%ing

;one



0 20 *0 +0 ,0 100

–+0

–*0

–20

0

20

*0

+0

,0

M$

M A !

Proposed Settings Pro&ide

!etter Protection

&'

)'''



Static $+ 'ncludes

3anual Control



40 Eleent *peration $&oids Generator

%aage %uring !lac, Start /esting



Po#er *scillations Entering 2

hile $+ 's in 3anual Control

0 10 20 90 *0 50 +0

–20

–10

0

10

20

90

*0

M$

M A !

&aa.ili%/

&ure

M'L

–10 0 10 20

–20

–10

0

10


) m

a g i n a r / ( s e c o n d

a r / o : m s "

;one 2



5ndesired *peration of

40 Eleent %uring 3EL /esting



0 20 *0 +0 ,0 100

–+0

–*0

–20

0

20

*0

+0

,0

M$

–20 –10 0 10 20 90

–*0

–90

–20

–10

0

10

20

90


one 2 Setting $ccording to

CFE Guide

&aa.ili%/ &ure

M'L

;one 2

&aa.ili%/ &ure

;one 2

M'L

M A !

) m a g




–+0

–*0

–20

0

20

*0

+0

,0

M$

M A !

–*0

–90

–20

–10

0

10

20

90


) m a g


$pparent 'pedance Enters

one 2 Causing 5ndesired *peration

7era%ing #oin% 7era%ing #oin%

0 20 *0 +0 ,0 100 –20 –10 0 10 20 90



–+0

–*0

–20

0

20

*0

+0

,0

M$

M A !

–*0

–90

–20

–10

0

10

20

90


) m a g i n a r / ( s e c o n d a r / o : m s "

$fter 'pro&ing Coordination

$pparent 'pedance 's *utside one 2

7era%ing #oin% 7era%ing #oin%

0 20 *0 +0 ,0 100 –20 –10 0 10 20 90



CFE Generator 5nits .a&e

.igh-'pedance Grounding



Characteristics of

.igh-'pedance Grounding

Ground 8aul% curren% is limi%ed (2 %o 15 A" %o

minimize core and <inding %:ermal damage

Ground 8aul%s cause oerol%ages on:eal%:/ :ases

&ommon ro%ec%ion se%%ings use long

dela/s 8or coordina%ion urose



Con&entional

64G %elay

Settings

Ma/ consider coordina%ion <i%: 3 8uses

and e=%ernal 8aul%s on :ig:-side ol%age

o8 GS> %rans8ormer



Concerns ith Slo# Fault

Clearing /ies

3ransien% oerol%ages due %o arcing and

in%ermi%%en% 8aul%s s%ress <inding insula%ion

#ro.a.ili%/ o8 second 8aul% increases a8%er8irs% 8aul% .ecause o8 %ransien% oerol%ages

and arc res%ri6es



Effects of Second Fault Lead to

3a7or %aage

Second 8aul% on ano%:er :ase roduces

:ig: curren%s %:a% lead %o di88eren%ial

elemen% oera%ion Second 8aul% on same :ase ./asses

:ig:-imedance grounding resis%or and

ro%ec%ion &3s (clearing %ime deends on+*G elemen% onl/"



Fault Clearing %elay 3a,es a

!ig %ifference

4ela/ed oera%ion o8 +*G causes second 8aul%

a% di88eren% <inding loca%ion

irs% :ase-%o-ground 8aul% Second 8aul%



'nterittent Ground Faults

Arcing 8aul%s <i%: lo< curren% can .e %o%all/ e=%inguis:ed

can reigni%e seeral %imes and are di88icul% %o de%ec%



'nterittent Fault $cceleration Logic

Ac%ia%es 5 s o.sera%ion <indo< <:en

+*G elemen% deasser%s 7era%es i8 +*G reasser%s 8or 9 c/cles

<:en o.sera%ion <indo< is ac%ie



For !etter Generator Protection8

Se% loss-o8-8ield elemen% according %ocaa.ili%/ cure

&onsider reduced oera%ing ol%age

condi%ions <:en coordina%ing loss-o8-8ieldelemen% <i%: minimum e=ci%a%ion limi%er



For !etter Generator Protection8

Quic6l/ de%ec% ground 8aul%s %o reduce ris6o8 :aing mul%ile <inding 8aul%s and %o

minimize genera%or damage

Al/ in%ermi%%en% 8aul% accelera%ion logic8or 8as% de%ec%ion o8 ground 8aul%s

>se 8ield een% reor%s and rogramma.le

logic %o imroe genera%or ro%ec%ion



9uestions:



$dittance Plane is $lso $ffected )y

oltage ariations

-0.01 0 0.01 0.02 0.03 0.04 0.05 0.06-0.04

-0.03

-0.02

-0.01

0

0.01

0.02

0.03

Real (Secondary S)

I m a g ( S e c o n d a r y S )

Admittance Plane

generator protection setting

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