9 Electrical Distribution

8/11/2019 9 Electrical Distribution

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© Confederation of Indian Industry

Electrical Distribution System




Transformer

Transformer

Heart of Electrical Distribution

Category

Power Transformers

Distribution Transformers




Types Of Transformers

Distribution Transformer

Normal Efficiency- 98 to 99

!ron loss is "# to "$ of full loa% copper

loss

Optimum efficiency occurs between &# to

'# of loa%ing




Types Of Transformers

Power Transformer

Normal Efficiency- 99 to 99($

!ron losses is )# to )$ of full loa%

copper losses

Optimum efficiency occurs between '# to

8# of loa%ing




!ssues of transformers

Secon% *argest loss ma+ing electricale,uipment

$ billions +./ of energy is lost as

loss per year ' of Total generation is lost in

transformers

*ife of transformer *ife cycle cost




*oss in Transformer

Efficient Transformer 0 " loss

Substantial at /ig/er ratings

*osses contribute% by

Core loss 0 No loa% loss

Copper *oss 0 Depen%s on loa%




Core losses-No loa% losses

Hysterisis losses

Due to magneti1ationan% %emagneti1ation

E%%y current losses Due to circulating

currents in core






Transformer Efficiency

Transformer efficiency - 98-99

Optimum efficiency occurs at $# loa%

7$ loa%

"## loa%




Transformer Efficiency

Optimum efficiency occurs w/ere

!ron losses Copper losses




T/ree P/ase Transformer-Typical

*oss C/art

•Loss in watts

")###"8)#")$#

)#######)###

""8)#"77#"###

9$##"&)#7$#

'8'#"##$##

* copper

*oss :.;

!ron *oss

:.att;

<=5 2ating




How to re%uce losses >

?se copper rat/er t/an

aluminum

?se t/inner core steel

laminations

?se a con%uctor wit/ a

larger area an% small

lengt/

?se better gra%e of core

steel to increase

resisti3ity

?se fewer turns in t/e

coil

?se more turns in t/ecoil ?se a core wit/

larger leg area

Ways to Reduce Load

Loss

Ways to Reduce No-Load

Loss




Case Stu%y

11 KV

2000 KVA

11 KV / 415 V

80% Load

2000 KVA

11 KV / 415 V

CB CB

CB CB

415 V




Case Stu%y

@ac+groun%

Capacity of transformer )### <=5

*oa% on t/e transformer is 8#

!ron loss A +.

* Copper loss A )# +.






Case Stu%y

12.5 MVA

110 KV / 22KV

12.5 MVA

110 KV / 22KV

22 KV 6 MVA LOAD

110 KV




Case Stu%y

@ac+groun%

Two Transformers :")($4=5; are operate%parallel

5ctual total effecti3e loa% is ' 4=5

loa% to t/e in%i3i%ual transformers is)&

*osses

!ron loss A )$ +.

*( Copper losses A 7) +.






11 KV

2000 KVA

11 KV / 433 V

2000 KVA

11 KV / 433 V

CB CB

CB CB

415 V

Case Stu%y




!solate Primary Of T/e !%le

Transformer

!%le transformer consumes power for

its in/erent magneti1ation losses

No loa% loss A +.

5nnual Sa3ings A 2s #(8 *a+/s




Transformer *ife

*ife of t/e transformer is &# years

Possible if t/e temperature of win%ings is

less t/an 8#°C

Depen%s up on t/e insulation of t/e core

or e3ery "#< %ecrease in win%ingtemperature copper losses fall by

(9

*owering of win%ing temperature

slows %own ageing of a transformer




Transformers Cooling

!nsulating oil acts as cooling me%ium

Oil flow is t/roug/ Natural t/ermo sip/on flow :no pumps;

orce% flow :pumps;

Heat e6c/angers or ra%iators transfer/eat from oil to en3ironment

ans may be use% to increase force%

con3ection o3er ra%iator fins






Case Stu%y-2a%iators En/ancement

)# 4=5 Power transformer is

operating at '$-7# loa%ing 8 Cooling fans :"($ +.; are running

ans are interloc+e% wit/

temperature

Transformer is tripping because of

/ig/ temperature !nsufficient cooling




Case Stu%y-2a%iators En/ancement

2e%esigne% :increase%; t/e si1e of

transformer ra%iators !n all & %irections by con%ucting a

separate stu%y

Still cooling fans are interloc+e%

wit/ win%ing temperature to a3oi%

t/e problems




@enefits

Power reliability is increase%

Cooling fans power will be sa3e% Cus/ion for more capacity

Temperature of t/e win%ing willbe re%uce%

2esistance of t/e win%ing will be

re%uce%

*oa% losses will also come %own






5morp/ous =s Con3entional








Comparison of Efficiency

Amorphous CRGO Amorphous CRGO

250 180 570 98.7 98.2

500 250 900 99 98.53

630 200 1000 99.1 98.54

730 365 1250 99.2 98.65

1000 450 1500 99.2 98.68

Rating (kVA)No Load Loss (W) Efficiency (%)

Cold-Rolled Grain Oriented silicon steel (CRGO).

f ffi i




Transformer efficiency






5%3antages

No Nee% for 5%%e% De3ices suc/ as!solation Transformers Harmonic

ilters *esser /eat generation %ue to lower

losses

Slower ageing of insulation

*onger *ife

Superior electrical performance un%er

/armonics con%ition

*esser 4agneti1ing current




Power actor




Terminology

5cti3e Power :+.;

Power t/at actually powers t/e e,uipment

an% performs useful wor+

2eacti3e Power :<=5r;

Power t/at magnetic e,uipment

:transformer motor an% relay; nee%s to

pro%uce t/e magneti1ing flu6

5pparent Power =ector sum of +. an% <=5r




5nalogy

Power factorA +. A +. A @eer<=5 +. B<=5r @eer B oam




Effect of Power actor




P Compensation met/o%s

met/o%s

Centrali1e% compensation

Distribute% compensation

4i6e% compensation






Power actor Compensation

5%3antages

Easy P( maintenance

Capacitor maintenance easy

Disa%3antages

4ore 3oltage %rop in %istribution O3er /eating of cable resulting in

failure

Suitable if %istance between PCCan% 4CC is less





Distribute% Compensation

MOTOR

SS PANEL

PCC

MCC

MOTOR





5%3antages

4inimum 3oltage %rop

*ow %istribution losses

Disa%3antages

4aintenance is %ifficult 5pplicable w/ere %istribution is

remote






4i6e% Compensation

MOTOR

REACTIVE CURRENT

FLOW

CAPACITOR

BANK

SS PANEL

PCC

MCC

4i6e% Compensation

MOTOR

REACTIVE CURRENT

FLOW

CAPACITOR

BANK

SS PANEL

PCC

MCC

P t C ti





5%3antages

oo% P( control

Easy maintenance

*ow %istribution losses

Common in Continuous Process

in%ustry

C it S l ti




Capacitor Selection

C/art 4et/o%

ormula 4et/o% Capacitor re,uire% :<=5r;

A +. 6 FTan cos

-"ΦΦΦΦ" 0 Tan cos

-"ΦΦΦΦ) G

Cos ΦΦΦΦ" 0 Present power factor

Cos ΦΦΦΦ) 0 Desire% power factor

!mpro3e O3erall P an% 2e%uce 4D




Case Stu%y

4ont/ly 53g P maintaine% at #(9' Sanctione% 4D 7## +=5

4in %eman% c/arges 7$ :$&7$ +=5; 2ecor%e% mont/ly 4D

'8## +=5

Hig/ %eman% c/arges






5ction ta+en !nstalle% a%%itional capacitor ban+s I

5PC to impro3e P

P impro3e% to #(99 +=5 %eman% re%uce% by )&# +=5

5%%itional benefits 2e%uce% 3oltage %rop in fee%ers

ee%er loss re%uction Cus/ion for capacity e6pansion







5nnual Sa3ing - 2s "#( *a+/s

!n3estment - 2s "$(# *a+/s

Paybac+ perio% - "8 4ont/s

@enefits of Power factor




!mpro3ement

*ower utility fees

!ncrease% system capacity 2e%uce% system losses

2e%uction in Power losses

A "##-"## 6 :Present Pf;J)

New Pf

!mpro3e Power actor Of enerator




"# 4. turbo generator

2ate% P #(8

Operating P #(9

enerator %eli3ers acti3e power I

reacti3e power

Efficiency of T %epen%s on operating

P Hig/er t/e P /ig/er is t/e efficiency







T Test %ata

9'(9"9'(#)$ *oa%

98("897($9$# *oa%98($97(987$ *oa%

98($'98(#8"## *oa%

#(99#(8Efficiency K P(





!mpro3ing P from #(9 to #(9'resulte% in impro3ement in efficiency

2e%uce% loss %ue to re%uction in current


5nnual Sa3ings 2s "&(8 *a+/s

!n3estment 2s "$(# *a+/sPaybac+ " 4ont/s

=oltage Drop




=oltage Drop

=oltage %rop is an in%ication of %istribution

loss

Causes of 3oltage %rop

Poor power factor

!na%e,uate cable si1e lai%

Poor contact surface at

Cable Termination

Cable Loints

ContactorsMSwitc/es

=oltage Drop




=oltage Drop

!n a large comple6 %istribution system

3oltage %rops are 3ery common

5cceptable limit in a P/( System is

&-$ =olts M P/ase

4ore t/an $ =MP/ase in%icates energy

loss in t/e %istribution

=oltage Drop 4easuring




=oltage Drop 4easuring

Proce%ure

4easuring instruments s/oul% be calibrate%

Simultaneous measurement of 3oltage in t/efee%ing an% recei3ing en% of t/e fee%er

4easure P( I Current

Note %own t/e cable si1e

C St % = lt D




Case Stu%y-=oltage Drop33 kV

2500 KVA

33 kV / 433 V37% Load

2000 KVA

33 kV / 433 V

CB CB

434 V

PCC-IPCC-II

419 V

C e St % =olt e D o




Case Stu%y-=oltage Drop

Obser3ations

Currently t/e PCC-! is supplie% from PCC-!!4easurements

=oltage at PCC-!! A && =

=oltage at PCC-! A &"9 = Drop in =oltage A "$ =olts :a3g;

*oa% current A 7&# 5

Power factor A #(99 Cable si1e A & 6 &## 6 ($ S,(mm

Case Stu%y =oltage Drop





Cable loss- "9+.

Causes of 3oltage %rop

Poor contact surface at

Cable Termination

Cable Loints

ContactorsMSwitc/es






33 kV

2500 KVA

33 kV / 433 V

13% Load

2000 KVA

33 kV / 433 V

29% Load

CB CB

PCC-IPCC-II

Operate% bot/ t/e transformers






3.740.132250033025.43.3PCC-!! )($4=5

5.040.298200059623.632.95PCC-! )4=5

6.780.3704250092625.43.3PCC-!! )($4=5

Total *oss *oa%2ate% +=5Operating +=5ull *oa% Cu lossNo loa% loss

Operation of bot/ transformers resulte% inre%uce% loa%ing

!ncrease in transformer losses by )+.

Subse,uent re%uction in cable losses an%net sa3ing potential was "7+.






5nnual Sa3ing - 2s '(8$ *a+/s

!n3estment - Nil

Ot/er opportunities




Ot/er opportunities

!ntegrate% online energy management

system 53oi%s t/e %ifficulties

@etter monitoring Dri3es w/ere to focus

Easy to compare wit/ ot/er plants



Tec/nical Specifications




p

Solar 4ill




5%3antages

uic+ !nstallation

Simple

Continuous Power

Supply

!n%ian Power eneration




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9 Electrical Distribution