BE Distribution 3rd slide

7/23/2019 BE Distribution 3rd slide

1/24

Factors affecting Distribution LossLoss dependence on Transformer Size

Suppose demand: 20 KW

Monthly energy sell : 4320 unit

The minimum standard size transformer required is 2!"#

Transformer $oss %ariation &ith transformer size

Transformer'ating(!"#)

*o $oad$oss(!W)

'ated $oad$oss (!W)

Monthly*o $oad+nergyloss(!Wh)

Monthly$oad $oss(!Wh)

Total +nergyloss (!Wh)

,er-entage+nergy $oss

2 0./0 0.30 2.00 2.1 .1 2.3/

0 0./ 0.0 /22.40 //.2 /33.2 3./0

/00 0.30 0. 2/1.00 4.0 220.0 .//

/10 0.44 /.30 3/1.0 2.3 3/.3 .40

200 0.10 /.10 432.00 2.30 434.30 /0.0


2/24

Loss dependence on Load center Size


3/24

5eeder &ise po&er loss


4/24

$oss Summary


5/24

Loss dependence on Load pattern

Suppose for the same load -enter &ithmonthly energy demand same as forpre%ious -ase i.e. Monthly energy sell :/2 unit

6ut the all energy is7 consumed in 3 hours

7 consumed in 6 hours



$oss %ariation &ith demand pattern


6/24

LT loss scenario


7/24

Loss dependence on feeder unbalancing

S-enario one all phase ha%e equal loading: 20 #

S-enario one feeder loading7 ,hase ': /0 #

7 ,hase 8: 20 #

7 ,hase 6: 30 #

S-enario three feeder loading7 ,hase ': /0 #

7 ,hase 8: /0 #

7 ,hase 6: 40 # 9f the loss in s-enario / is 1

The loss in s-enario 2 is aout .

The loss in s-enario 3 may e around /0


8/24

;ther 5a-tors

The loss also depends on -ondu-tor size

7 Thi-! -ondu-tor: less loss

7 Thin -ondu-tor: more loss

7 +.g the loss &ith dog -ondu-tor is aout /


9/24

Summary

Transformer should e appropriately installed tominimized transformer loss. 9t should not e o%ersized.

The load -enter size should e as small as possile.The feeder should e -onfigured so that the -onsumers

should e as -lose to the sour-e ( transformer). To redu-e the per-entage loss its required to in-reasethe other a-ti%ities than lighting only.#s far as possileminimize other use during pea! hours.

While -onne-ting -onsumers to supply phase alan-ingshould e !eep in mind.

Thi-! -ondu-tor -ause less loss ut high -ost-ompromise is done to sele-t appropriate -ondu-tor


10/24

Distribution Transformer Size & Location

In urban area go for maximum Transformer size and are

usually higher due to high load density as far as the LT

conductor capacities permits (No & size!

In "ural the maximum size of LT is limited by #o$er

Loss & %oltage drop (its recommended limit is around 'm! and Transformer size are usually smaller due to lo$

density and load coincident beha%ior

ut

This choice is also reflected by the utilization )oltage

le%el and the transformer %oltage ratio (The abo%e is for

*+,)!


11/24

Location of transformer

-s far as possible the Distribution transformer must be

located at the center of gra%ity the Load center In rural areas some times a single transformer is used to

ser%e ./* or more small %illages located in proximity

In such case follo$ing theoretical approach may be used to

locate approximate transformer location

Ta'e a reference point on the x/ y coordinate/ The location

0/ 1 is then find using/


12/24

In the selection of LT line routethe follo$ing criteriashould be ta'en into consideration2

3 The routing of the lines (radial length! has been made asshort as possible so as to minimize the %oltage drop andline loss

3 The LT lines are mostly routed along the feasible roads/foot trail4hilly road so that

The transportation of lines4construction materials to site is easier

This also facilitates the maintenance of lines

3 The line routing is done in such a $ay that maximum

number of households could be co%ered3 -%oids placing poles in flooded or land 3 sliding areas

3 5inimizes deforestation as much as possible

3 5inimizes $idth of ri%er crossings


13/24

,rimary >istriution 5eeder >esign

? @onfiguration

The primary distriution system design

in-ludes the routing and -ondu-tor sele-tion to

ser%e the distriution transformers from

Sustation. The optimization pro-edure usually used for

-ondu-tor and routing sele-tion is one of the

follo&ing:

7 minimizing the length of -ondu-tor

7 minimizing the -ost

7 minimum po&er transfer and distan-e approa-h.


14/24

$etAs -onsider fi%e different distriution transformers of same size and same

numer of -ustomers are desired to e -onne-ted from the sustation

through a radial distriution feeder of similar -ondu-tor. ;ut of pra-ti-ally

feasile feeder layout options t&o are sho&n in 5ig.(a) ? ().

S4S-

6

D

7(a! 8ption9-

. 'm

. 'm

. 'm

. 'm

. 'm

S4S-

6

D

7(b! 8ption9

. 'm

. 'm . 'm

. 'm

. 'm

*ote that:7 The load to e ser%ed in oth the -ases same

7 @ondu-tor length same

6ut it -an e sho&n that the losses in option 7# is aout /. times

greater than optionB6


15/24

Suppose the transformer size at ea-h of the node is S !"#.

Then the po&er flo& through the ran-hes -an e easily

-omputed and is sho&n in 5ig. elo&.

S4S -

6

D

7(a! 8ption9-

. 'm

. 'm

. 'm

. 'm

. 'm

:S

;S

*S

.S

S

S4S -

6

D

7

(b! 8ption9

. 'm

. 'm . 'm

. 'm

. 'm

:S *S

SS

S


16/24

9t is to e noted that this differen-e in losses are only due

to the fa-t that the ran-h po&er for the same load are

signifi-antly different in t&o options.

#lternati%ely it -an e said that the node po&ers ha%e to

tra%el larger distan-e in optionB# than optionB6.

Summarized in Tale elo&:


17/24

9t -an e sho&n that the -ondition for &hi-h po&er loss is

minimum "oltage >rop is also minimum.

#lso for the same -ase 'eliaility is also ma=imum Ta!e an e=ample &ith /00 -onsumers at ea-h node

7 5ailure rate 0.04

Node Tra%elingdistance

#robabilityoffailure4yr

#robable No ofconsumer notgetting supply4yr

- 2 0.0

4 0./1 /1

6 1 0.24 24

D 4 0./1 /1

7 1 0.24 24


18/24


19/24

'ea-ti%e ,o&er 5lo&:


20/24

&,, ')-,+ pf lag

&,, ')-,+ pf lag

&,, ')-,+ pf lag

&,,, ')-

**4&&')

SS -

6

&


21/24

A!A S"#STAT$%& S!L!'T$%&

Ser%i-e area

9nput


22/24

Sustation sitting

-%ailability of land for the %arious necessary e>uipment of there>uired capacity and re>uired number of distribution feeders forthe identified ser%ice area of the substation

The cost of land

8pportunity for ?eeder geta$ay

The cost of preparing the site (slope/ drainage/ underlying soil androc'!

The cost of transporting material

7sthetic re>uirements (fencing/ landscaping!

-%ailable options for expanding the substation capacities/ additionof distribution feeder and extension of sub transmission line for thene$ substation that may come in future

"ight of $ay for transportation of substation e>uipments


23/24

Ser%i-e #rea identifi-ation ? Sizing

The expected substation ser%ice area has to be fixed asserting the

follo$ing@

The area $here the reach of the distribution feeder is acceptableThis is to assure that the entire load $ithin the ser%ice area isade>uately ser%ed (%oltage/ reliability!

No e>uipment is o%er loaded considering the constraint in the plansuch as limitations on the size of transformers/ circuit brea'ers etc

Distribution feeder costs and its losses are $ithin the acceptablelimit considering the social/ geographical/ political and othersimilar scenarios

7xisting substations are utilized $here%er possible That is theareas that can be ser%ed by this proposed substation but at highercost or loss in comparison to the existing surrounding substation(s!ha%e to be discarded


24/24

Sele-tion of su transmission line route

#ossibly a%oiding any crossing of proposed sub transmission lineroute $ith another high (**') and abo%e! or 5edium (')!%oltage line this increase the cost due to high to$er

5inimizing the length of line

"eliability of the system $ithin the acceptable limit

5aintaining the %oltage profile and line loss (as from thepreliminary assessment! in the proposed and effected existing subtransmission line $ithin the standard limit

8%erall in%estment and running cost to be minimum

Nearest possible motor able road or ma=or trac's

-%oiding of proposed alignment crossing through the rural4urbansettlements

-%oiding of deforesting and long ri%er crossing

5inimizing the Land ac>uisition problem

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BE Distribution 3rd slide