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A
PROJECT REPORT ON
ISLANDING SCHEME OPERATION
Submitted In Partial Fulfllment o the Requirement
For The
Award o Post Graduate Diploma in Thermal Power
Plant Engineering
S!"ITTED !#$% Arunkumar K Arunachalam R Pramod Kumar
Pandey
Ranjit M Sriram V
GIDED !#$%
Mr.Mahalingaswamy (Electrical)
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Manager!"S#E$E
CERTIFICATE
%his is to certi&y that this is a 'onade record o& rojectwork entitled
&IS'A(DI(G S)*E"E +PERATI+(,
$arried *ut 'y
Arunkumar K+ ,-P/,0Arunachalam R+ ,-P/1
Pramod Kumar Pandey+ ,-P/22
Ranjit M+ ,-P/20Sriram V+ ,-P/31
4n artial &ulllment o& the re5uirement &or the award o&6Post raduate /iloma in %hermal Power Plant
Engineering7(P../.$.)
*8ered 'y
-S. Energ/ 0entre o e10ellen0e2Torangallu
/uring the academic year 1, 9 1,1
1
Energ/ )entre o E10ellen0e(Recogni:ed 'y $entral Electricity Authority! o;t. o& 4ndia)
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"r3 S3 4arti5e/an "r3 "ahalingaswam/ "r3 Ramesh !abu34 "r3
Prashanth5umar )
(AM) (Manager! Project uide) (Manager) (/y.Manager)"S#E$E! %oranagallu "S#E$E !%orangallu "S#E$E ! %orangallu "S#E$E!%oranagallu
A)4(+.'EDGE"E(T
#e nd it most di hel in this roject. %he
words that &ollow are merely the &ormal e=ression
o& our dee sense o& inde'tedness that is 'etter
treasured in thoughts than said in words.
4t is leasure gi;ing ;er'al e=ression to our
&eeling o& deeest gratitude
towards!Mr.S.Karthikeyan(AGM),Mr.Prashanth
kumar c. (Asst.manager)! "r3
"ahalingaSwam/6manager72 and
"r3 Ramesh !abu 53 6"anager73
#e would also like to e=ress our secial
gratitude to the lant eole "r3De8ara9ulu
?
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6"anager2 Ele0tri0al "aintenan0e2S!%:7
"r3Rama5rishna 6"anager2Ele0tri0al
"aintenan0e2S!%II7 and our roject guide "r3
"ahalingaswam/ who guided during the entire
roject. #e are ;ery much inde'ted to him &or his
unreser;ed co+oeration! constant guidance and
constructi;e criticism.
@astly we are thank&ul to god! our &riends and
all &aculties o& -S.E)E &amily &or their moral
suort and co+oeration.
CONTENTS:
. 4ntroduction
1. enerating units on 4slanding
?. enets o& 4slanding
2. /etection o& 4slanding
-. Modes o& *eration
3. S@/ &or di8erent modes with conditions
B. Particulars o& di8erent modes
C. $onse5uences o& 4slanding
0. Post 4slanding oeration
,. @oad distri'ution ta'le
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. $ommunication during 4slanding
1. $ommunication &ailureD $ontingency logics
?. uture Modication
NT!O"#CTON
%he ower systems oerated 'y the utilities inde;eloing countries like 4ndia su8er &rom a large ga'etween demand and generation! inade5uatetransmission caacity! and non+uni&orm location o& theload centers and generating stations. *ccurrences o&&aults in such systems! in most o& the cases! end uwith the worst conse5uences (i.e.! comlete 'lackout).
A 'lackout can 'e re;ented in real time throughcontrolled segregation o& a system into a num'er o&;ia'le islands together with generation andFor loadshedding. %his is called System islanding.
/enition o& 4slandingD 4slanding is a rocess in which a
generator continues to suly ower to a articular load
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e;en when grid suly is not a;aila'le.
rid islanding scheme is a set o& rotecti;e relays!
connected at the islanding 'us + these relays will sense a
distur'ance in the grid and gi;e a tri command to theincomer 'reaker whene;er the grid distur'ance e=ceeds
a set limit. y oening the incomer 'reaker! the
lant is isolated &rom the grid.
%he "S#E@ thermal ower lant at %oranagallu is the
energy source &or the adjoining steel lant and its
rimary urose is to suly su
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through a line &rom the steel comle= called "P@+1.
$PP+ is connected to the 11,KV islanding 'us (GS+1)
through two tie lines &rom the $PP+ unit 'us to MS/S and
&rom MS/S to 11,KV GS+1 ;ia two trans&ormers %R+ and%R+1 o& ;oltage rating 11,F??KV.
#hen all three are a;aila'le! the islanding load which
can 'e catered to is 1B, M#. 4& one or more o&
these are una;aila'le due to any reason! there are
three other load le;elsD 1,-M#! B, M# and C
M#. %hese are called di8erent oeratingmodes. As
steel roduction grows year 'y year and new
generating units are added su'se5uently! these M#
le;els may undergo changes in &uture.
$ENE% TS O% S&AN"NG SC'EM E
%he 'enets o&&ered 'y the scheme are huge. %hey arelisted 'elowD. 4t re;ents triing o& 'oth "S#E@ and "S#S@ units!
hence re;ents hea;y losses which will occur due to tri
in 'oth the lants. 4n a'sence o& the scheme! whene;er
a &ault occurs in the grid and grid ;oltage le;el dros! so
does the ;oltage o& the 'us which connects it to the
generating units. %he steel lant loads also deri;e
ower &rom the same 'us. Hence! in e;ent o& a &ault! the
generating unit tris due to load star;ation whereas
steel lant loads shut down due to lack o& re5uired ower
suly.
1. 4t ensures continuous suly to the o=ygen lant
critical to the working o& steel mill. "P*$@ ("indal Pra=air
*=ygen $omany @td) is also situated in the steel lant
B
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camus and is the key to the working o& the main units
like last urnace ()! asic *=ygen urnace (*)! and
$oke *;en ($*) among others. 4& the suly to the
o=ygen lant is interruted! steel roduction comes to agrinding halt.
?. 4& the "S#E@ unit tris! it takes at least 2 hours to
get it into normal oeration mode again and a lot o&
H*(Hea;y uel *il) and @*(@ight uel *il) consumtion
in the 'oiler is necessary to 'ring the 'oiler temerature
to the ignition temerature o& coal &or its com'ustion.
%his is a;oided 'y islanding.
2. 4t hels in &aster restoration o& the other unit
e;en i& it has tried. %he au=iliaries o& this unit would
'e sulied ower &rom the running islanded unit &or its
restart and a changeo;er is done later.
"ETECTO N O% S&AN"NG
/etection o& islanding is done 'y three di8erent relaysnamely under ;oltage relay! under+&re5uency relay andrate o& change o& &re5uency relay which senses the;oltage and the &re5uency in the islanding 'us GS+1.
%he ;oltage and the &re5uency setting o& these relays areselected such that these settings are lesser than that o&the generator under+;oltage and under+&re5uency setting
so that the generator will not go &or tri and the systementers into islanding mode.4slanding is considered as detected in the &ollowingconditionsD
. Voltage magnitude o& islanding 'us dros to
C
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B-I o& normal ;oltage le;el &or more than .- sec.B?I o& normal ;oltage le;el &or more than ,, ms.
1. re5uency o& the 'us ;oltage dros to
2B.3 H: &or more than 1 sec.2B.- H: &or more than -, ms.
?. re5uency J - H: with d&Fdt,.- H:Fsec. %his is Rateo& $hange o&re5uency (R*$*) criterion.
2. @ine L @ine 1 L 4$%+ L 4$%+1 circuit 'reakers allare in oen condition.
-. us couler oens on its own rotection. 4t may 'eeither earth &ault or o;er current rotection.
3. us 'ar rotection o& GS+ acted.B.Sensing o& no ower Now O1I in 'oth lines with dFdt1 H:Fsec
Gnder any o& the a'o;e listed conditions! 'us couleroens! islanding detecting anel gi;es an alarm andislanding detected signal is assed to ?? kV MS/S and?, M# $ontrol Room.
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MO "ES O% OPE!ATON "#!NGS&AN"NG
%he 'elow are the 2 di8erent modes o& oeration when
the system goes into islanding.
QSee ta'le in Pg+3 &or load distri'ution in di8erent modes.
CPP-2
Net Net Gen. LOAD SHEDDING
MODES OPTIONS SBU-I CPP-I Max
Mi
n
Ma
x
Mi
n
JSWSL
LOAD Max Min
MODE-5 1 118 65 109 85 292 268 270 22 -2
MODE-4
2 118 65 84 55 267 238 205 62 33
3 118 0 109 85 227 203 205 22 -2
MODE-3
4 118 65 0 0 183 183 170 13 13
5 118 0 84 55 202 173 170 32 3
6 0 65 109 95 174 160 170 4 -10
MODE-1
7 118 0 0 0 118 118 118 0 0
8 0 65 109 05 174 70 118 56 2
9 0 65 95 55 160 120 118 42 2
)+(DI TI +( S F+ R DI FFERE (T "+DES$. Mode -D
a) 4sland /etected.
') "S#E@ 4sland Gnit Healthy
c) $PP+ eneration B,M#
d) $PP+1 et generation 0,M#
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1 . Mode 2D
$ase +
a) $PP+1 et generation O C-M#') $PP+1 et generation -- M#
c) $PP+ eneration B,M#
d) "S#E@ 4sland Gnit Healthy
e) 4sland detected.
$ase +1
a) $PP+1 et generation 0,M#
') $PP+ eneration O 3-M#
c) "S#E@ 4sland Gnit Healthy
d) 4sland detected.
3-M#
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3 . Mo d e 3:
$ase +
a) $PP+1 et generation O -- M#
') $PP+ eneration B,M#
c) "S#E@ 4sland Gnit Healthy
d)4sland detected.
$ase +1
a) $PP+1 et generation O C-M#
') $PP+ eneration O 3-M#
c) "S#E@ 4sland Gnit Healthy
1
, M#
3- M#
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d) $PP+1 et generation -- M#
e)4sland /etected.
$ase+?
a) "S#E@ 4sland Gnit %ri.
') $PP+ eneration B,M#
c) $PP+1 et generation 0,M#.
d) $PP+1 et generation O,0M#
e) 4sland /etected.
2 . Mode D
$ase +
a) $PP+1 et generation O -- M#
?
,M#
3-M#
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') $PP+ eneration O3-M#
c) "S#E@ 4sland Gnit Healthy
d) 4sland /etected.
$ase +1
a) $PP+1 et generation --M#
') $PP+ eneration B,M#
c) "S#E@ 4sland Gnit %ri
d) Gn Healthy o& Mode+?! $ase+?
e) 4sland /etected
$ase+?
a) "S#E@ 4sland Gnit %ri.
') Healthy o& Mode+?! $ase+?
2
, M#
3- M#
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c) $PP+1 et generation --M#
d) $PP+ eneration B,M#
e) 4sland /etected
$PP+ @ocal islandingD
a) 4sland /etected
') $PP+1 et generation O --M# and "S#E@ 4sland Gnit
%ri
c) $PP+1 %ri
PA!TC#&A!S O% "%%E!ENT MO"ES
%here are &our di&&erent modes a;aila'le &or oeration
and the ma=imum steel lant load to 'e sulied cannot
e=ceed 1B, M# as deicted in the ta'le a'o;e. %hemodes are automatically selecta'le through ser;er at
MS/S deending on generation o& the units. Real+time
mode is always annunciated irresecti;e o& 4slanding
detection.
-
3- M#
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Post islanding! SG+ oerates in seed control mode
and $PP+ and $PP+1 in constant load mode. 4n normal
oeration! all o& them are at constant load and seed. 4n
those cases where SG+ is una;aila'le! $PP+1 is tooerate in seed control mode during islanding.
$PP+ unit generation has two sla'sD a'o;e B, M# or'elow 3-
M#. #hen islanding gets detected! in the &ormer case! it
is 'rought to B, M# 'y assing an islanding signal to
$PP+. 4& itTs the latter case (generationO3- M#)! it goes
&or a tri.
$PP+1 generation has di8erent oerating sla's!'ecause it utili:es waste gases &rom all o;er the steellant as &uel. $onse5uently! it has 0 di8erent 'oilers toroduce steam 'y 'urning these gases at di8erentlaces in the lant.
$PP+1 oerates in one o& these
'locksD
4. C-M#O$PP+1O,0M#
44. --M#O$PP+1OC-M#
444. - M#O$PP+1O,0 M# (*nly in Seed $ontrolmode)
Since $PP+1 has a 'and o& generation o& ower and loadis constant the di8erence 'etween the generation and
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the load has to 'e shed 'y the seed control unit. ore=amle in mode - we ha;e the generation 'etween101M# and 13CM# and the load on the steel side is1B,M#.
4& the generation is ma=imum 101M# and the load is1B,M# the di8erence (101+1B,) 11M# has to the shed'y the seed control unit.
4& the generation is minimum 13CM# and the load isconstant at 1B,M# now the di8erence o& 1M# has to 'eshed 'y the load side in order to maintain the &re5uencyconstant at -,H:.
4& "S#E@ islanding unit tris!
A signal ost islanding unit tri signal assed to $PP+1 and it goes into seed control mode with last twominute a;erage &re5uency as the set oint. Howe;er incase o& $PP+1 % 'reaker oening 'oth @R/ (@oadrejection de;ice) > 4sochronous mode (i.e the unit now
runs at -,H:) are re;erted 'ack.
A signal &rom $@4MS ser;er shall initiate $PP+oeration to B,M# through @ocal %$S. 4& $PP+ isoerating 'elow 3-M# it has to 'e tried. or achie;ingthis! a local scheme at $PP+ %$S is 'uilt which shallinitiate $PP+ UesFo signal.
ormally! i& $PP+1O--M#! it goes &or a house load(au=illaries) oeration 'y oening o& 11,KV reaker at11,KV Switch Uard.
%he mode changeo;er &or @oad shedding is
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automatic 'ased on status o& Gnits at "S#E@ > $PP+and generation at $PP+1.
%he current islanding detection anel is used &or4slanding signal generation.
)onsequen0es o Islanding$
4n case o& islanding > 'us couler oen
4& either 4$%+ or 4$%+1 is connected to the islanding 'us!
the tri signal is gi;en to the resecti;e 4$%.
4slanding detected signal will ena'le G EH%$D
%o change o;er &rom @*A/ to SPEE/ control
A seed re&erence set oint will 'e generated &rom
EH%$ 'ased on 'elow &ormula
(R ; +ne hour a8erage a0tual speed ? 7@?3?7BC?? < : rpm
R%/ ;alue is limited to ?,CC.0, rm on uer side
and 1C0,.1, rm on lower side. R%/ will 'e &ast
tracking R in seed control mode.
4slanding detected signal will annunciated in control
room! MS/S control room > "P*$@.
GENE!ATON S'E""NG POSTS&AN"NG
C
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A&ter the system gets islanded! it is imerati;e tomatch totalgeneration with total load. As it turnsout! in most o& the cases! generation is in e=cesscomared to load 'ut to di&&erent e=tent in di8erent
modes. Hence! to maintain the generation load 'alance!ost islanding generation shedding logics areincororated in the scheme.
As can 'e understood &rom the a'o;e gure! the
generation shedding logic comes into lay i& ost
islanding! the generation e=ceeds load 'y 3, M# or
more (i& less! it can 'e taken care o& 'y seed
controlled unit). 4& it is so and $PP+ generation is
greater than B, M# sla' (then $PP+ UESF* signal
W)! $PP+ is gi;en tri command.
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4n case! e;en a&ter $PP+ is tried ($PP+ UESF*
signal W,) and still the di8erence is ersisting and
"S#E@ islanded unit is healthy (signalW,) ! $PP+1
unit goes &or a house load oeration 'y oening o&circuit 'reaker at 11, kV switchyard.
4n case! i& "S#E@ islanded unit has tried ("S#E@
island unit tri signalW) and i& the di8erence
'etween generation and load e=ist more than 3,M#
$PP+ has to go &or tri and the $PP+1 should 'e
running in the seed control mode.
%his logic is e&&ecti;e only &or -,, milliseconds a&ter
islanding detection a&ter that the generation and the
load cannot 'e distinguished and they attain the
same ;alue. 4& this generation shedding is not done
within -,,mS it leads to e=cess generation and the
&re5uency raises in all the units and the seed o& the
tur'ine increases in the seed control unit ultimatelyunit goes &or tri due to o;er seeding o& tur'ine. So!
generation shedding has to 'e done 'e&ore it.
4n an islanded network! at any oint o& time i& $PP+1 has
suly steam to the steel lant! additional load throw o8
has to 'e initiated at the MS/S. 4& MS/S is not initiating!
then either %R+? or %R+2 loads can 'e cut+o8 at "S#E@
end in concurrence with MS/S.
1,
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'+AD DISTRI!TI+($
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COMM#NCATON "#!NG S&AN"NG:
#hen the system gets islanded! Xislanding detectedsignalT is to 'eassed on to the main ser;er in ?? kVMS/S and the $ontrol Room. %he real time mode should'e continuously Nashing at the ser;er and the controlroom screen. %herea&ter! according to the mode! the$4@MS ser;er has to send tri signals to suita'le steelloads and generating units. Each o& these stes needcommunication 'etween the islanding detection anel!
main ser;er at ?? kV MS/S! control room! SG+! $PP+!$$P+1 and the steel loads in;ol;ed at di8erent times.
or this urose! a redundant dual otical &i'er
network has 'een
esta'lished 'etween these locations. 4t is resonsi'le
&or &ast transmission and recetion o& the signal
commands which is critical &or the success&ul oeration
o& the scheme. Remote %erminal Gnits (R%Gs) areinstalled at all generation and loading units in;ol;ed.
%hey are caa'le o& digital communication i.e. digital
inuts and digital oututs.1B, M# @ogic shall 'e
residing in ?? MS/S main ser;er and it shall rocess
the data as er logic and issue necessary
commands to resecti;e R%GTs as /igital *ututs.
COMM#NCATO N %A!E:CONTNGENC & OGCS
4& the *$ communication links &ail in one or morelaces! it uts the entire scheme at risk. So! &or 'acku!
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some hardwired signals are also sent and recei;ed'etween the generating units! 11, kV *#S (*erator#ork Station)! 1Y?, M# unit control room and ?? kVser;er. Se;eral logics ha;e 'een ut in lace as a
contingency measure
4. 4& communication &ailure haens at $PP+ endthen $PP+ shall go &or a %R4P. or this thecommunication &ailure is to 'e *RT ed with $PP+
UesFo signal.44. 4& communication &ailure haens at $PP+1 end!then contingency
arises as in case o& "S#E@ 4slanded Gnit %ri! Seedcontrol signal cannot 'e trans&erred to $PP+1. So!triing o& $PP+1 11,KV end 'reaker is initiated(4slanding detectedL Post $PP+1 communication &ailL %riing o& "S#E@ Gnit) &or house load oeration o&$PP+1.
444. 4n case o& communication &ailure haening at
11,KV "S#E@ end! one hardwired signal &or Postislanded "S#E@ Gnit tri is e=tended to MS/Sser;er. Howe;er the net eneration o& $PP+1 shallalso not 'e a;aila'le! hence changeo;er to $PP+1ross 9 3M# shall 'e taken as $PP+1 et generation&or Mode selection.
%#T#!E MO "%CAT ONS N T 'ESC'EME:
ow! it is roosed to increase the islanding load &rom1B, to ?,,M# as the steel lant constant load hasincreased o;er the recent ast due to increase inroduction. %he roosal is still under discussion.
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