Post on 20-Feb-2018
7/24/2019 Negative Sequence Protection
http://slidepdf.com/reader/full/negative-sequence-protection 1/35
Copyright © SEL 2014
Negative-Sequence
Differential Protection
Principle!" Sen!itivity" an# Security
Bogdan Kasztenny
Normann Fischer
Héctor J. Altuve
Schweitzer Engineering Laboratories, Inc.
7/24/2019 Negative Sequence Protection
http://slidepdf.com/reader/full/negative-sequence-protection 2/35
$he Nee# for Sen!itivity
• High-resistance line faults
• urn-to-turn faults
♦ ransformers
♦ !enerators
♦ "hunt reactors
• #a$acitor %an& failures
7/24/2019 Negative Sequence Protection
http://slidepdf.com/reader/full/negative-sequence-protection 3/35
Stator an# %otor $urn-to-$urn &ault!
• "tator turn-to-turn faults
♦ "$lit-$hase $rotection 'hydro(
♦ )ero-se*uence overvoltage 'steam(
• No electrical $rotection for rotor turn-to-turn faults
• +i%ration sensors
7/24/2019 Negative Sequence Protection
http://slidepdf.com/reader/full/negative-sequence-protection 4/35
'ren(t Stator $urn-to-$urn
&ault! )*plau!i+le,#onstruction indicates that
turn-to-turn faults are im$lausi%le
,e do not $rotect againstturn-to-turn faults
urn-to-turn faults evolve until
detected as ground or $hase faults
,e never see turn-to-turn faults
7/24/2019 Negative Sequence Protection
http://slidepdf.com/reader/full/negative-sequence-protection 5/35
./ Principle
• "ensitive• Fast
• nherently secure
7/24/2019 Negative Sequence Protection
http://slidepdf.com/reader/full/negative-sequence-protection 6/35
$he Secret to Sen!itivityDifferential Current,
athematically
/*uivalent
No 012 differential 3 no 014 differential
7/24/2019 Negative Sequence Protection
http://slidepdf.com/reader/full/negative-sequence-protection 7/35
./ Li*itation
7/24/2019 Negative Sequence Protection
http://slidepdf.com/reader/full/negative-sequence-protection 8/35
enerator
o#el
• 5igital model
ca$a%le of
simulating stator
turn-to-turn faults
• 67.0 &+8 9:: ,8
!";-connected
• A+< and s$eed
controls
7/24/2019 Negative Sequence Protection
http://slidepdf.com/reader/full/negative-sequence-protection 9/35
Sa*ple enerator &ault!Stator $urn-to-$urn &ault 35
9
$resent
69: Hz
$resent
7/24/2019 Negative Sequence Protection
http://slidepdf.com/reader/full/negative-sequence-protection 10/35
Sa*ple enerator &ault!E6ternal &ault
9
$resent
69: Hz
$resent
7/24/2019 Negative Sequence Protection
http://slidepdf.com/reader/full/negative-sequence-protection 11/35
' %otating $ran!for*er,
"tator 6= ω'rotor( > ω'field( 3 : • ω ? dc in F
"tator 9= ω'rotor( @ ω'field( 3 9 • ω ? 69: Hz in F
7/24/2019 Negative Sequence Protection
http://slidepdf.com/reader/full/negative-sequence-protection 12/35
Sa*ple enerator &ault!E6ternal &ault
9':Hz(
F'69:Hz(
67
9':Hz(
F'69:Hz(
7/24/2019 Negative Sequence Protection
http://slidepdf.com/reader/full/negative-sequence-protection 13/35
Sa*ple enerator &ault!Stator $urn-to-$urn &ault
9':Hz(
F'69:Hz(
1 C 67
9':Hz(
F'69:Hz(
7/24/2019 Negative Sequence Protection
http://slidepdf.com/reader/full/negative-sequence-protection 14/35
)&120 785 9er!u! )2:0 785
<otor
urn-to-urnFaults
7/24/2019 Negative Sequence Protection
http://slidepdf.com/reader/full/negative-sequence-protection 15/35
Stator &iel# Current ;n+alance
7/24/2019 Negative Sequence Protection
http://slidepdf.com/reader/full/negative-sequence-protection 16/35
Evolving &ault E6a*ple2refault /Dternal E urn
7/24/2019 Negative Sequence Protection
http://slidepdf.com/reader/full/negative-sequence-protection 17/35
Evolving &ault E6a*ple :0S&5
9':Hz(
F'69:Hz(
7/24/2019 Negative Sequence Protection
http://slidepdf.com/reader/full/negative-sequence-protection 18/35
Stator &iel# Current Differential
7/24/2019 Negative Sequence Protection
http://slidepdf.com/reader/full/negative-sequence-protection 19/35
Evolving &ault E6a*ple .S&5
9':Hz(
F'69:Hz(
7/24/2019 Negative Sequence Protection
http://slidepdf.com/reader/full/negative-sequence-protection 20/35
Evolving &ault E6a*ple .S&5
7/24/2019 Negative Sequence Protection
http://slidepdf.com/reader/full/negative-sequence-protection 21/35
Phy!ical achine o#el
• 99: +8 9: &+A8 7 $oles• 9 Gindings $hase8 6:: turns each
• EI slots8 6I60 $itch
• 68 98 78 E8 and 6: turn-to-turn faults
• 2rime mover > induction motor
7/24/2019 Negative Sequence Protection
http://slidepdf.com/reader/full/negative-sequence-protection 22/35
E6ternal &ault E6a*ple
9':Hz(
F'69:Hz(
IE
9':Hz(
F'69:Hz(
7/24/2019 Negative Sequence Protection
http://slidepdf.com/reader/full/negative-sequence-protection 23/35
E6ternal &ault E6a*ple
9':Hz(
F'69:Hz(
7/24/2019 Negative Sequence Protection
http://slidepdf.com/reader/full/negative-sequence-protection 24/35
Stator $urn-to-$urn &ault E6a*ple <5
9':Hz(
F'69:Hz(
E: C IE
9':Hz(
F'69:Hz(
7/24/2019 Negative Sequence Protection
http://slidepdf.com/reader/full/negative-sequence-protection 25/35
Stator $urn-to-$urn &ault E6a*ple <5
9':Hz(
F'69:Hz(
7/24/2019 Negative Sequence Protection
http://slidepdf.com/reader/full/negative-sequence-protection 26/35
Conclu!ion!
• Negative-se*uence differential♦ s eDcellent for $rotecting lines and transformers
♦ Needs security for # saturation
♦ #annot detect turn-to-turn faults in stators and
reactors
• :"F and 01"F $rovide very sensitive stator
and rotor turn-to-turn fault $rotection
7/24/2019 Negative Sequence Protection
http://slidepdf.com/reader/full/negative-sequence-protection 27/35
/ue!tion!,
7/24/2019 Negative Sequence Protection
http://slidepdf.com/reader/full/negative-sequence-protection 28/35
$he Secret to Sen!itivity%e!training Current,
012 014
oGer restraint $rovides sensitivity %ut challenges security
7/24/2019 Negative Sequence Protection
http://slidepdf.com/reader/full/negative-sequence-protection 29/35
%e!training Current Purpo!e
<eflect the stress on $rotection systemcom$onents8 #s in $articular8 that can cause
s$urious differential current
=he magnitude of every current that
contri%utes to the differential signal must
contri%ute to the restraining signal
=
Negative-se*uence restraining current
does not meet this re*uirement for
%alanced faults
7/24/2019 Negative Sequence Protection
http://slidepdf.com/reader/full/negative-sequence-protection 30/35
$he Secret to Sen!itivity'##re!!ing C$ Saturation>
• "ecurity $ro%lems under # saturation
• Need for eDternal fault detection logic
7/24/2019 Negative Sequence Protection
http://slidepdf.com/reader/full/negative-sequence-protection 31/35
' %otating $ran!for*er,
7/24/2019 Negative Sequence Protection
http://slidepdf.com/reader/full/negative-sequence-protection 32/35
$urn-to-$urn &ault Protection ?ith <2/
7/24/2019 Negative Sequence Protection
http://slidepdf.com/reader/full/negative-sequence-protection 33/35
$urn-to-$urn &ault Protection ?ith <2/
urn-to-urn Fault
"ystem Fault
7/24/2019 Negative Sequence Protection
http://slidepdf.com/reader/full/negative-sequence-protection 34/35
Stator &iel# Current Differential
#om$ensation
Fre*uency Angle
7/24/2019 Negative Sequence Protection
http://slidepdf.com/reader/full/negative-sequence-protection 35/35
Evolving &ault E6a*ple :0S&5