Module III - Concepts and Principles of Distribution Loss

8/13/2019 Module III - Concepts and Principles of Distribution Loss

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DEVELOPMENTTHROUGHINTERNATIONALPARTNERSHIPS

DRUM TRAINING PROGRAMA U.S. Agency for International Development (USAID)

Funded Program

BEST PRACTICES INDISTRIBUTION LOSS REDUCTION

Program Presenter Program Presenter

National Power Training Institute CORE International, Inc.

January 27

February 1, 2005, Faridabad


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III. Concepts & Principlesof

Distribution Losses

2

M. V. S. Birinchi

CORE International, Inc.

BEST PRACTICES IN

DISTRIBUTION LOSS REDUCTION


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Losses

Technical losses

Commercial losses T & D losses

AT & C losses

Concepts & Principles of Distribution Losses


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Technical Losses Every element in a power system

a line a transformer etc

consume some energy whileperforming their expected duty.

Cumulative energy consumed byall these elements constitutes

technical losses



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Commercial Losses

Occur on account of

Non performing meters

Under performing meters Meters not read

Application of lower multiplication

factors

Defects in CT / PT circuitry

Pilferage by manipulation

Theft by Direct tapping etc.



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T & D & Revenue Loss

The total of Technical &

Commercial losses are called

T&D losses

In addition to the above,

revenue loss occurs on accountof non-realisation of billed

demand



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AT & C Losses

AT & C is abbreviation for

Aggregate Technical & Commercial

loss

Example:Units Input 100 MU

Units sold 70 MU

Losses 30 MU

T&D loss% 30%

If Revenuecollections are 90%

of demand

Out of 70 MU of

sales revenue isrealised for 63 MU

AT & C losses

are 37%



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Historical background for high losses

Developing Countries could not invest in

network expansion commensurate with

rapid load growth

Network expansion carried out onadhocism & haphazard basis

Diversity factor of 1.5 was adopted which

is now lost due to restricted supply

Usage of lower size conductor, lowvoltage pockets, absence of reactive

power control etc.



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Loss Scenario in India

Sl.

No.System Segment

Existing

Level

Target

Level

% diff

3 to 4

1 2 3 4 5

1. Trs. System 4.5 2.0 225%

2. Sub Trs. System 4.0 2.25 178%

3. Primary (HV) Distn. 7.0 3.00 233%

4. Secon (CV) Distn. 7.5 1.00 750%

5. Total 23% 8.25 279%

[Tolerable level can perhaps be 4 + 4.0 + 5 + 2 = 15%]



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Causes for Technical Losses

Lengthy Distribution (11 KV & LT) lines

11 KV & LT lines are extended for

unduly long distances in RuralAreas (low load density)

Inadequate Conductor sizes

Initially lower size conductors were

used and are not replaced whenload growth has taken place.



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Length of 11 KV line corresponding to different loads_______________________________________________________________________Size of KVA-KM for 8% Maximum of Load thatconductor voltage drop at length of can be(with 0.8 PF line connectedcode No.) (KM) (KW)

________________________________________________________________________50 MM2ACSR 10, 640 30 355

Rabbit

30 MM ACSR 7,200 20 360

Weasel

20 MM2ACSR 5,120 15 341

Squirrel

. The figures are for a conductor temperature of 60o C. For a conductor temperatureof 50oC, the above figures shall be about 3% higher and for a temperature of 70oC about 3%

lower.

Standards for 11 KV lines



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Standards for LT linesLength of 415 volts line corresponding to different loads________________________________________________________________________Size of KW-KM for 8% Maximum of Load thatconductor voltage drop at length of can be(with at 0.8 PF line connectedcode No.) (KM) (KW)________________________________________________________________________30 MM2ACSR 11.76 1.6 7.35Rabbit20 MM2ACSR 7.86 1.0 4.86Weasel13 MM2ACSR 5.58 1.0 5.58

30 MM2

AAC ANT 12.06 1.6 7.5416 MM2Gnat 6.96 1.0 6.96________________________________________________________________________The figures are for a conductor temperature of 60 C. For a conductor temperature of



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Causes for technical losses(Contd.)

Wrong location of DTRs

DTRs are not located centrally &

farthest consumers face low voltages

For every 10% voltage drop losses

increase by 21% and for every 20%

voltage drop losses increase by 44%

DTRs to be relocated at load centre to

minimise losses.



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Over rated DTRs

Under loaded DTRs are a source forhigh avoidable iron losses

Taking village as a unit the loads can

be readjusted among all DTRs in the

village for optimal use of installed

capacity



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Low Voltage Pockets

Where as the permissible voltage

variations are 6% the voltages atsome points go below 10% and in rare

cases even more.

Full load current drawn by motors go up

by 15% for every 10% drop in voltage On load tap changers are not made use

of due to certain inhibitions



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Causes for technical losses(Contd.)Low Power Factor

In majority of Distribution circuits the p. f

is between 0.65 & 0.75

Low p. f. contributes to high distributionlosses

When shunt capacitors of adequate rating

are fixed at load end, experiments showed

10% improvement in voltage20% reduction in current

6% overall reduction in energy.



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Causes for technical losses(Contd.)Bad workmanship

Bad joints are a source of power loss

Proper jointing techniques should beadopted for firm connection

Connections at line jumpers, Trs. bushing

rods, drop-out fuses, isolators, LT switch

etc shall be periodically inspected. Timely replacement of deteriorated

wires, worn out clamps etc



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I O S P(Integrated optimum System Planning)

An integrated approach towards optimum

system planning for prioritizing the works is as

follows

Reconfiguration Change of feed from onesource to another

Reconductoring Enhancing conductor size by

replacement or conversion to double circuit

Shunt / series capacitor (switched / unswitched) Auto Booster

Additional link lines

Combination of two or more of the above



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I O S P (Contd)

For each of the approach as above

LRVI (Loss Reduction & Voltage

Improvement) are determined

Cost benefit ratio is calculated and

least cost option for maximum LRVI is

selected.

IT IS IMPORTANT TO CONDUCTTHESE STUDIES FOR LOAD GROWTH

UPTO 5 YEAR HORIZON.



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Software packages available

Hardware Software packages available

Work Stations CADPAW, CAD PAD ABB, USA

Plotters DINIS ICL, UK

Digitisers PRAO EDF, France

Printers CYME CYME inc., CanadaScanners DPA SCOTT & SOOTT, USA

PSS Power Technologies

SINIX Siemens, Germany

DISBUT APSEB

CAPSI WIPRO

DISTPLAN CPRIPOWER NET GECE



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H. V. D. S.

High Voltage Distribution System

The HT to LT ratio is now skeweddue to very long LT network For 100 KVA load at 11 KV the

amperage is 5 Amps where as at LTit is 140 Amps.



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Conversion of existing LVDS to HVDS

Single phase HVDS and 3 phase

HVDS are both practised

As majority of existing Agl. pump sets

are with 3 phase motors, 3 phase

HVDS is more acceptable.



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Sample results of conversion toHVDS in APSPDCL

Location

Voltage Losses%

Before After Before AfterKottur 350 420 18.63 5.47

Patnam 340 420 16.82 5.30

Bangarupalem 320 430 16.30 3.77

Murakambattu 385 430 13.76 5.44



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Additional Benefits Motor Burn outs drastically gotreduced Fuse blow outs are practically NIL Reliability of supply has improvedconsiderably Consumer satisfaction has gone up.



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Steps taken to reduce commercial losses Accurate Metering Plan (appropriate range) Correct selection of C.T. ratios High and sustained accuracy meters for

high value services Intensive inspections by pooling up staff Reduce Meter exceptionals by changingdefective meters One time regularisation of unauthorisedservices



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Steps taken to improve MBC

Introduced spot billing through hand-held computers Networking of Electricity Revenueoffices cash collection centres Multiple payment options Web enabled services



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In this Training Course Exchange of experiences expertisetowards Reduction of Technical losses Reduction of commercial losses Efficiency improvement in MBC

Metering, Billing Collections. Thus reduce AT C losses.



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THANK YOU

FOR

YOUR ATTENTION

INTERACTION INVITED

Documents

Module III - Concepts and Principles of Distribution Loss