Islanding Project

7/25/2019 Islanding Project

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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

2


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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#


d)4sland detected.

$ase +1

a) $PP+1 et generation O C-M#

') $PP+ eneration O 3-M#


1

, M#

3- M#


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d) $PP+1 et generation -- M#

e)4sland /etected.

$ase+?

a) "S#E@ 4sland Gnit %ri.


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#


d) 4sland /etected.

$ase +1

a) $PP+1 et generation --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

3


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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

B


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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

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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+($

1


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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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Islanding Project