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Breakdowns
More
frequent | Minimum, except
for damage
& Incidence breakdowns
due
to
cau
sed
by
oth
er
age
ncies.
of
faults various reasons
causing
damage
to
equipment
4,
Restoration
Supply can be restored in
minimum
time.
Skills
required
are
also
minimum
5.
Interruption
Maximum
uninterrupted
6.
7.
8.
9.
10.
MINISTRY
_|
Cannot be assured
Takes more time for identify the
fault and rectification, Skills
of
highest
order
and
special
equipment are needed
for
location of fault as well
as
rectification.
and Minimum and fairly uninte
rrupted
supply supply can be maintaine
d
Life of service Less
High
Losses
Maximum and theft prone Neg
ligible and theft free.
by
hooking
to
bare
conductors
Accidents
Possibilities of accidents Ver
y rare.
are more and risk oflife is
involved
Facility
for| Needs more land for;
Can be installed on minimu
installation of| installation of Sub
m
-stations. land. But costly due
to need for
in line subRMUsetc.
stations..
Aesthetic
beauty
Cannot be maintained
Can be maintained.
_|
WORKMANSHIP, PROPER JOI
NTINGetc.
Stringing of the Line Conductor
:
REC hasstandardized the follow
ing
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sizes of conductors for 33 KV, 11
KV and LT lines.
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[11 KVlines
Best Practices in Distribution Loss Reduction
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i)
ii)
7/2.17 mm (20 mm>
7/2.59 mm (30 mm?)
ACSR (AAAC)
ACSR (AAAC)
7/2.11 mm (20 mm.
7/2.59 mm (30 mm)
7/3.35 mm (50 mm?)
ACSR (AAAC)
ACSR (AAAC)
-ACSR (AAAC)
ii) 7/3.35 mm (50 mm’)
LT lines
i)
ii)
iii)
iv) 7/2.21 mm (25 mm’)
v)
_7/3.10 mm (50 mm’)
ACSR(AAAC)
AAC (AAAC)
AAC (AAAC)
Conductor Erection:
The erection of overhead line conductor is very important phase In construction.
The erection of conductor can bedividedinto 4 parts.
1. Transport of conductors to worksite
2. Paving and stringing of conductors
3. Tensioning and sagging of conductors and
4. Jointing of conductors
Having transported the conductor drum to the tension point, the drum should either be
mounted on the cable drum supports or jacks or hung by means of chain pully of
suitable capacity suspended from a tripod. The conductor should be passed over the
pole on woodenor aluminum snatched pully blocks provided with low friction bearings.
The conductor shall be raised to a minimum height of 5 mt. above ground by rough
sagging.
The mid span joints of conductors can be carried out by twisting joint or compression
joints. The twisting joints for aluminum conductors and ACSRconsist of relatively thin
walled aluminum sleeves, the end of the wire should project a few centimeters beyond
the endof the sleeves. The projected wires are given a sharp bend to keep them from
slipping out of the sleeve. Twisting Tongues are preferably to be used for joints and
jumpers.
Sagging
and Tensionin
On completion of the paving: of conductors and making mid spanjoints if any, tensioning
operation will commence. Temporary guys will have to be provided for both anchoring
supports. At the tensioning end one of the conductors is pulled manually up to a certain
point and then come-along clamp is fixed to’ the conductor to be tensioned:The grip ‘of’
the comealong clamp is attached to double sheave pully block or the pull lift (TIRFOR)
machine and gradually tensioned.
The conductor should then be sagged in accordance with the sag temperature chart for
a particular conductor and span. The sag should then be adjusted in the middle span of
the section.
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The stretch of the conductor has to be taken out before stringing in order to avoid the
gradualincrease in sag due to setting downof the individual wires. There are two ways
of accomplishing this
1. Prestressing
2. Over tensioning
1. Prestressing: In this method, the conductoris pulled upto a tension considerably
above the EL correct figure, but never exceeding fifty percent of breaking load for
a
short period of say 20 minutes. As this method requires more time andinvolves the use
of stronger tackle to secure high tension, the other method of over-tensioning
is
commonly adopted.
2. Over-tensioning: The method consists of pulling up the conductor to a tension
a
little above the theoretical tension for the prevailing temperature andfixedit up
at that
tension with a correspondingly reduced sag. After a certain time the conductorwill settle
down to the correct sag and tension. A tension of 5% to 8% more than the theoreti
cal
value has been found to be suitable for the sizes of ACSR and AAC conductors.
The
ambient temperature during the sagging may recorded ‘correctly.
.
Conductors can be sagged correctly only when the tension is the same in each span
throughout the entire length of the section. Use of snatch blocks reducesthe friction and
|
chances of inequality of tension in various spans.
Sagging can be accomplished by different methods, but most commonly used
method
for the 11 KV line is "SIGHTING" by use of targets placed on the supports below
the
cross arms. The targets are light strips of wood clamped to thepole at a distanc
e equal
‘to the sag below the conductor when the conductor is placed in snatch blocks.
The
lineman sees the sag from the next pole. The tension of the conductor is then reduce
d
or increased; until the lowest part of the conductor in the span coincides with
the
lineman'sline of sight.
Whensagging is completed, the tension clamps shall be fixed. The clampscanbef
itted
_ on the conductor without realising the tension. A mark is made on the conductorat a
distance from the cross arm equal to the length of complete Strain insulators. Before
the
insulator set is raised to position all nuts should be free. A come along clampis
placed
on the conductor beyond the conductor clamp and attached to the pulling unit.
The
conductor is pulled in sufficiently to allowthe insulator assembly to be fitted
to the
clamp. After the conductor is clamped to the insulator assembly unit may be release
d
gradually. After the stringing is completed all-poles, cross arms, insulators, fittings
etc.
are checked up to ensure that there havebeen no deformities.
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The next step is to place the conductor on the top of the pin insulator from the snatch
block and removing snatch blocks. Conductors are then fastened to insulator by the use
of aluminum wires.
Before tying the conductor to the insulator, two layers of aluminum taps should be
wrapped overthe conductorin the portion where it touches the insulator.
Normally in straight lines the conductors are run onthe top of the insulators. When there
is a smail angle of deviation the conductoris placed inside groove and binded.
OVER HEAD LINES - CROSSINGS - RAILWAYS/RIVERS/P&T LINES/ ROADS REGULATIONS
Railway
Crossings:
Before commencing work on any crossing, approval of the Railway and the Electrical
Inspector in writing shall be obtained for the proposed location and detailed design of
the crossing. For this propose, data, designs and drawingsrelating to the crossing shall
be submitted in duplicate by the ownerto the Railway and the Electrical Inspector.
Classification of Crossings: For the purpose of these regulations, electric overhead
lines crossings are classified in accordance with the clearances required under the
following categories.
1.
Category 'A':
Tracks electrified.
2.
Category'B':
a
‘Tracks already electrified or likely to be converted toor
electrified on 25 KV AC system within the foreseeable future:
3.
Category Cc. Tracks notlikely to be electrifiediin the foreseeable future.
Minimum clearance between the over head lines and Railway Tracks:
(i)
Crossing over tracks already electrified shall normally be located at mid
spans of the overhead traction conductors, but in any case shall not be less
than 6 meters from the nearest traction. mast.
(ii) The minimum height aboverail level of the lowest portion of any conductor
under conditions of maximum sagshall be as follows.
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m
including 11
KV
Above 11KV/10.0m
including
MINISTRY O
Best Practices in Distribution Loss Reduction
Distribution Reform, Upgrades and Management (DRUM)
Training Progra
7.6m
33
8.6 m
6.3m
8.8m
6.4m
KV
Note: Low and Medium voltage (upto 650V
) crossing of category A only will be
obligatory by meansof underground cables, (m
- metre)
re
volts
Above
650]
volts upto 33
KV
Only by Cable
Only
12.5m
10.5 m
Note: If the crossing is located on a metre guag
e or a narrow guage section, likely to
be converted to broad guag
e; clearance applicable to broad guage shall
be adopted.
Minimum clearance between conductors and
any Railway Structure:
The minimum vertical and horizontal clearanc
es between any conductors and any
Railway buildings and: structures other than tract
ion supports and overhead equipment
under the most.adverse conditions shall be in
accordance with Rule 80 of IE Rules,.
1956.
Minimum clearance between owners and
Railway conductor:
The minimum clearance between any of the owne
r’s conductor or guard wires and the
railway conductor shall
not be less than 2 metres.
—
,
Insulators:
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Categories A&B: Double set of strain insulator strings shall be used in the crossing
- Span in conjunction with a yoke plate where necessary. It is recommended that each
string of such strain insulator shall have one insulator disc - more than that used in
normal span of the overheadline.
Category 'C': Strain insulators, suspension insulators or pin insulators may used as
required.
Guarding: The minimum height above the rail level to the lowest level of any cradle
guard and guard wires under conditions of maximum-sag shall be asfollows:
Category 'A&B': The sameclearances as given in clause 19(1) shall apply.
Category 'C': The minimum height of 6.9 m shall apply for broad guage and 6.1, for
metre and narrow gauges.
B. RIVER CROSSINGS:
_ For the rivers on whichthe crossing is to be done, the dates of high flood level of atleast
_the previous 20 years is to be obtained from the revenue authorities and the structures _.
are to be erected so that in rainy season also they will be approachable under the
flooded conditions of the river. In case of navigable rivers, the structures should be so
designed as to give sufficient clearance between the lowest conductor and the highest
flood level. Consultation which Navigation authorities is necessary. In case of non_navigable rivers, the structures should be designed in such a way that the lowest
conductor should be 3 mts above the maximum flood level. This is necessary because
floodwater may carry trees and their branches.
C. CROSSINGS OVER TELEGRAPH OR TELEPHONE LINES AND P.T.C.C.
Communication circuits coming under the influence of electric field of high voltage
' power lines experience extraneous induction, which may introduce noise in
communication equipment and cause danger to the-equipment ‘and persons handling
them.
Therefore,it is very essential that whenever powerlines and communication lines pass
close to eachother suitable measures are taken. Approval of PTCC (Power Telecommunications Co-ordination Committee) may be obtained.
Further, while crossing the telecom lines, the following points may be observed.
1)
The powerlines cross over the telecom lines because the Dia of powerline
conductors is generally greater than telecom line conductors.
2) The angle of crossing shall be as far as possible 90°: but shall not be less
than 60°.
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am
3)
A safe clearance between the commun
ication lines and overhead power
lines has to be maintainedin accordanc
e with the PTCC code of practice.
4)
Power contact protectors are to be
installed on all conductors of teleco
m
lines at crossings with HV powerlines.
5)
The telecom lines shall be erected clo
se to the support of the OH powerline
s
for increased clearances.
D. ROAD CROSSINGS:
The ground clearance of the guard
wire and strength of the supports on
either side of
the road have to be considered in inst
alling a cradle guard at the road cros
sings. The
Supports on either side of the road
on which the cradle guard terminate
s are earthed
separately and the line should not cro
ss at an angle less than 60°. The saf
e minimum
distances between the Support of OH
lines and road had to be kept in vie
w while
planning road crossing.
The clearances above groundlevel
of the lowest conductor shall bein
accordance with
Rule No.77 of IE Rules 1956.
See Also Tables for
Pawn a
.
Permissible Spans
Clearances at Railway Xings
Clearances at Road Xings
Clearances. & Spacings from Buildings
Clearances at Highways
,
Clearances between power and Telephon
eLines etc
Section of Conductor Size and
Impact on Losses
Like in any other system, the power
system should be efficient. This mea
ns that the
ratio of the powerutilised by the ulti
mate consumers of electric power to
the power
‘produced at the generating statio
ns must be as high as possible.
In
othe
r words the
losses occurringin carrying electric pow
er from the generator to the consumers
must be
kept at the minimum. These loss
es are called "Line Losses" and
occ
ur in the
transmission and sub-transmission lin
es, Step up and step down transform
ers primary
‘and secondarydistribution line and dist
ribution transformers.
These losses are I?R losses in the resi
stance of the conductor and equipment
in the
line, iron losses ‘in the transformersetc
.
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Lowline losses result in a low cost perunit to the consumer. For the country as a whole,
low line losses mean betterutilisation of the sources of energy,
.In India, line losses vary form region to region from 15-30%. This is extremely high
comparedto about 8-10% in the developed countries of Europe, America and Japan.
This shows that the percentage losses need to. be brought down to reasonable level in
orderto improvethe efficiency of the distribution system.
This assumes great urgency and importance in view of the acute shortage of power.
Factors contributing towards Increased Line Losses:
The major amount of losses in a power system are in primary and secondary
distribution lines; while transmission and sub-transmission lines account for only about
30% of the total losses. Therefore the primary and secondary distribution systems must
be properly planned to ensure losses within acceptable limits.
The factors contributing to the increase in the line losses in the primary and secondary
systems:
1.
Lengthy Distribution Lines:
The primary and secondary distribution lines in rural areas; by and large radially laid,
usually extend over long distances. This results in high line resistance and therefore
high 12R lossesin theline.
Becauseof the above reason, the rural loads contribute towards increasedline losses.
2. . Inadequate Size of Conductors:
Rural loads are usually scattered and generally fed by radial feeders. The conductor
size of these feeders should be properly selected.
The size of the conductor should be selected on the basis of KVA x KM capacity of
standard conductorfor required voltage regulation.
Table provided below indicate the length of lines for 11 KV and 415 volts corresponding
_. to different loads for the voltage regulation prescribed by IE Rules; for different sizes of
conductors respectively.
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Table-1: Length of 11 KV line corresponding to different loads
‘50 MMZ ACSR
Rabbit
| 30 MM* ACSR
130.
7,200
20
360
5,120
15
341
Weasel
20 MM* ACSR
Squirrel
1358
The figures are for a conductor temperature of 60° C. For a conduc
tor temperature of
50° C, the abovefigures shall be about 3% higher and for a tempe
rature of 70° C about
3% lower.
Table-2: Length of 415 volts line correspondingto different loads
30M
Rabbit
20MM*ACSR-
.
7.86
Weasel
13 MM* ACSR
5.58
30 MM? AAC ANT 12.06
16
MM’
.
sO
7.35
1.0
14.86
1.0
1.6
5.58
7.54
oo
AAC/6.96
1.0
6.96
Gnat
The figures are for a conductor temperature of 60° C.. For a conductor
temperature of
50° C, the above figures shall be about 3% higher and for a temperature
of 70° C about
3% lower...
3.
Distribution Transformers not Located at Load centre on the Secon
dary
Distribution System:
Often DTs are not located centrally with respect to consumers.
Consequently, the
farthest consumers obtain an extremely low voltage even. though
a reasonably good
voltage level is maintained at the transformers secondaries. This again
leads to a higher
line losses. (The reason for theline losses' increasing as a result
of decreased voltage
at the consumersterminally are explainedin para - 5)
.
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Therefore in order to reduce the voltage drop In the line to the farthest consumers, the
distribution transformer should be located at the load centre to keep voltage drop within
permissible limits and thus minimise the losses.
4,
Over-rated Distribution Transformers and Leading to Under-Utilisation:
Studies on +1 KV feeder have revealed that often the rating of DTs is much higher than
the maximum KVA demand on the feeder. Over rated transformers draw an
unnecessarily high iron losses. In addition to this iron losses in over rated transformers
the capital costs locked upis also high.
From the aboveit is clear that the rating of DT should be judiciously selected to keep
the losses with in permissiblelimits.
For an existing distribution system the appropriate capacity of distribution transformer
may be taken as very nearly equal to the maximum KVA demandat good PF (say 0.85)
Such an exercise has been carried out for a number of distribution systems and
transformers with capacity of 25, 63,100,160, 315 KVA and standardised for different
systems with powerfactors and diversity factors.
5.
Low Voltage (less thandeclared voltage) at Transformers and Consumers
Terminals:
Whenever the voltage applied to induction motor varied from rated voltage, its
performance is affected. Within permissible voltage variation of +/- 6% in practice, the
supply voltage varies by more than 10% in many distribution systems. A reduced
voltage in case of induction motor results in higher currents drawn for the same output.
For a voltage drop of 10%, the full load current drawn by the induction motors increase
by about 10% to 15% the starting torque decreases by nearly 19% and the line lossesin
the distributor increases by about 20%.
_As the bulk toad of rural areas and small scale industrial areas consists of induction
motors, the line losses in the concerneddistribution systems may even touch 20%.
The above situation is corrected by operating an "on-toad-tap changing” in the power
transformer situated at high voltage sub-stations 66/11 KV and 33/11 KV sub-stations
and providing on the 11 KV feeders a combination of switched capacitors and automatic
voltage regulators.
Further, the "off load tap changing”in distribution transformers is adjusted prior to the
commencement of agricultural load season which. is readjusted before the on-set of
monsoons whenthe rural load is small if the off-load tap changing gearis available.
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Bas
6.
Low Power Factor:
In most of the LT distribution circuits, it is found that the
PF ranges from 0.65
to 0.75. A
low PF contributes towards high distribution losses. For a
givenload, if the PF is low,
the current drawn is high. Consequently, the losses propor
tional to square of the
current, will be more.
Thus, line losses owing to the poor PF can be reduced by
improving the PF. This can
be donebyinstalling of shunt capacitors.
Shunt capacitors can be connectedin the following ways:
(i)
Shunt capacitors are connected on the secondary side (11
KV side) of the
33/11 KV power transformers.
Table 3 shows from the studies carried out on 11 KV
lines, how the improvement of
power
factorresults in considerable reduction of losses.
Table-3: Reduction of Line Losses with Improvementi
n Power Factor
(A)
38.9
Mtoe
300
1.0
300
27.2
13.4
After
(ii)
Line losses in LT distribution lines may also be considerab
ly reduced by
installing shunt capacitors of optimum rating at vantage points
as decided during load
stations.
The optimum rating of capacitor banks for a distribution syste
m is 2/3rd of the average
_KVAR requirementofthat distribution system. The vantage
pointis at 2/3rd the length of
the main distributor from the transformer.
,
A study madein an urbandistribution system fed from a
200 KVA, 11. KV/415 volts
transformer with 300 HP CL of more than 200 consumers
having small loom loads
showed therangeof PF ofthe distribution system varied from
0.65 to 0.70. The reactive
power requirement was 135 KVR. The inductive loads occur
red on the distribution
syste
m between 7 AM and 8 PM: onall the working days
with almost const
ant loadcycle. The capacitor bank rating 42.5 KVAR were installed
at 2/3rd the distance from
the transformer on the maindistributor and were switched
on and off manually at 7 AM
and 8 PM respectively on all working days. The loss reduction
was thus found to be 67%. The released capacity in this particular study was 42 HP,
which could be supplied
to the additional consumers.
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A more appropriate mannerof improving this PF of the distribution system and
thereby reduce the line losses is to connect capacitors across the terminals of the
motors (inductive load). The extent of reduction of line losses in this manner depends
mainly on the extent to which the PF of consumer is improved. In this case, the
capacitor is connectedin parallel directly to the terminals, the capacitor being switched
on and off together with the equipmentitself.
Manyelectricity supply authorities are including a clause in terms & conditions of supply
making it compulsory for the consumers to provide capacitors of adequate ratingforall
types ofinstallations with connected loads of 5 HP and above.
By connecting the capacitors acrossall individual inductive loads it is observed that
10% voltage improvement 20% reduction in current and reduction of losses upto 9%
can be achieved depending uponthe extent of PF improvement.
7.
Bad Workmanship Resulting in Poor Contacts at Joints and Connections:
Bad Workmanship contributes significantly towards increase in distribution losses. In
this context, the following points should be bornein mind.
i)
Joints are a source of power loss. Therefore the numberof.joints should be
Kept to a minimum. Proper jointing techniques should-be used to ensure: firm
connections.
ti)
Connections to the transformer bushing-stem, drop-out fuse, isolator, LT
switch etc. should be periodically inspected and properjoint ensured to avoid sparking
and heating of contacts.
ili)
Replacement of deteriorated wires and services should also be madetimely
to avoid any cause of leakage andloss of power.
7.
First Segment Leaving Substation.
In a radial distribution systemthe first segment leaving the substation carriesall the |
load. This first segment is the one or several spans from the substationto thefirst tap
(junction) point.
In manycasesthis first segment contributes to (a) most of the technical losses (KWH, =
I**2Rt heating), and (b) to excessive voltage drop ( = IR).
A strategy is to increase the conductorsize ofthis first segment.
e Larger conductor(in terms of cross sectional area).
e Double or triple conductor with the samesize conductor.
Since losses (KWH, and voltage drop) are directly proportional to resistance (see the
above formulae), doubling the cross sectional area haives the losses (kWH and voltage
drop) in the segment.
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The above technique works for both MV and LT Systems.,
thoughits affect is more
noticeable on the LT feeders.
Contrastthis technical improvement where the conversion
fromLT (400 volts) to 11 kV
HVDS results in a 756 fold decreasein losses [ = (1100
0/400)**2 J.
Pilferage of Energy:
In addition to the above, pilferage of energy through
manipulation of metering, direct
tapping, application of wrong multiplying factors,
non performing meters, under
performing meters etc cause commercial losses. Since
it is often not possible to
measure the stolen energy and, therefore, cannot be
charged to any one. Stolen energy
is, therefore, considered as a part of T&D losses.
Unscrupulous consumers extract energyillegally eithe
r by-passing the energy meteror
by connecting leads directly to the distribution lines.
Electricity supply authorities take
various measuresto stop theft of energy as below:
1)
Surprise inspections are carried out by vigilance squa
ds.
2)
The energy meter is housed in a separate box seal
ed and made inaccessible
to the consumers. The fuse cut-outs are provided
after the meter.
3): The separate box shall be located outside
of the customer’s premise
(property line) in a location that is (a) readily acces
sible to utility personnel
(meter readers, maintenancestaff, inspectors and
auditors, etc.) at all times
(nights, weekends, ‘holidays, as well as workdays
), and (b) which is in a
public location visible to all persons.
oo
wires.
5) _ The energy meter manufacturers are asked
to provide the potential link
inside the body of the energy meter and not insid
e terminal cover. This prevents the potential link to be disconnected by the
consumer.
6)
Heavy fines are imposed on consumers found comm
itting theft of energy
including imprisonment.
It must be stated that the consumer stealing energyis
imposing extra financial burden
on honest law-abiding consumers. Further high
line losses result in increased
consumption of fuel, oil. etc. used in the generation
of electric power. Therefore, it is
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necessary that line losses
minimum.
(including pilferage of energy) are to be kept downto
A unit saved is one and a half units saved for the system and this slogan is well worth
remembering.
1)
To enable the designing and operating personnel in each power supply
undertaking to determine the specific causes of interruptions and take
suitable remedial measures to improve the standard of supply.
2)
3)
To determine whether any improvementin service continuity is necessary to
any consumer or group of consumers and to ensure that expenditure on
improvementsis incurred whenit is most needed.
To keep a Discom informed of the performance of its various operating
systemsordivisions.
INTEGRATED OPTIMUM SYSTEM PLANNING (IOSP)
(Distribution Net Work)
Introduction
The distribution system in developing countries is faced with low voltage and highloss.
The twin problem of the losses and voltage drop in distribution feeders are
interdependent and varies with the pattern of loading on the feeders. Powerlosses of
primary distribution system shall be between 3% to 5%. The maximum limits of voltage
:. variation at customer premises as per the Indian Electricity Rules are +6% and —9% at
_ » high voltage and +6% at low voltage. The loss reduction and voltage improvement can
be achieved by adding system facilities like erection of additional substations, setting up
of non-conventional energy sources, etc., or through short term measureslike network
reconfiguration, reconductoring, employing. shunt of series capacitors, or voltage .
boosters. The short term measures are cost effective and can be executed in a shorter
period. An integrated approach to be adopted for the LRVI problem of large scale
practical distribution network is discussed in this chapter for an optimal cost effective
strategy to upgrade the existing primary network such that losses are within the desired
range of 3-5% and alsosatisfy the statutory voltage limits at customer premises.
Short Term Measures
i) The Distribution Network in developing countries were expanded in adhoc mannerto
minimize the initial investment cost; and long range planning studies are not generally
undertaken. This situation has given a vast scope for reconfiguring the network to
minimize the losses.
The term network reconfiguration includes any oneorall the works indicated below:
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a) Formation of new links to minimize within a
feeder to form a tree stracture.
b) Erection of interlinking lines to change
the area of feed from one substation to
another and balance the load amongthe subs
tation.
c) Bifurcation of existing feeder to form parallel
paths of powerflow.
Network reconfiguration among feedersis effec
tive only when the voltage drop between
the nodesto be linked is rich and the distance
between the nodesis short. The nodes to
be linked have to be selected taking the quot
ient of voltage difference and the distance
between the nodesas criteria. Network reconfig
uration within a feederis effective only
when zig-zag factoris high. Zig-zag factor is defi
ned asthe ratio of total length of feeder
to the beeline distance between the Distributi
on substation and minimum voltage point.
Thelinks have to be chosenso as to create a tree
structure.
Shunt Compensation
The loadincident onthe distribution system is
mostly inductive, requiring large reactive
power. The best methodis to compensate the
reactive powerat the load end itself butit
is difficult to implement in practice. Hence, prov
iding compensation on the distribution.
system is essential. The shunt Capacitor supplies
constant reactive powerat its location,
independent of the load. So, optimal compensa
tion provided for peak load condition
may result in over compensation during light
toad conditions, necessitating automatic
switching schemes. The problem of determin
ing the number, size and location of shunt
Capacitors required to be provided is formulat
ed as an optimization problem. Objective
function is the cost of energy saved due to redu
ction of power losses by the installation
of capacitor banks less the annual cost of capa
citors installed. The voltage constraints
need not be considered, as the Capacitors are
switched on.andoff along with load to
avoid over voltage during low load operation;
and capacitor alone cannot economically
improve the voltage during peak load period to
Satisfy the statutory lower limit.
Series Compensation
The maintenance of voltage at customer prem
ises within Statutory limits at Il loads is the
responsibility of utility. Series Capacitor intr
oduces negative reactancein the line and
improve the voltage which in turn also reduces
the power losses. The main advantage
of series capa
citor is the quantum of compensation is
highly responsive of series
_ Capacitor is that the quantum of compensation
is highly responsive to load current and
series capacitor can be kept in the circuit
during the complete load cycle, without
causing any adverse effect of over voltages,
during low load conditions. The problem of
determination of optimal location and capacity
of series capacitor is formulated as an
optimization problem. The objective function
is similar to that of shunt compensation.
The voltage constraint is that the voltage at
the location of capacitor shall not exceed
permissible upper is less than the difference
between the permissible upper limit of
voltage and voltage at the location of capacito
r without series capacitor. Solution to the
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problem of determination of optimal capacity and location of series capacitor is obtained
through an interactive approach.
. Automatic Voltage Booster
The functioning of Automatic booster (AVB)is similar to that of series capacitor. AVB is
an on load tap changerIt boosts the voltage at its point of location in discrete steps and
this in turn improves the voltage profile and reduces the losses in the section beyondits
point of location towards receiving end. An AVB generally has a total voltage boost of
10% in four equal steps. The loss reduction is directly proportional to voltage boost and
maximum permissible voltage boostis limited by the difference between the permissible
maximum voltage and voltage at the point of location of AVB. The problem of
determination of optimal location and percentage of boost of boost of AVB is formulated
as an optimization problem. The objective function is the cost of energy saved due to
desirable constraints are that the voltages at all sections should not exceed the
statutory upper and lower limits. An interactive type of algorithm is adopted in the
proposed solution approach.
Network Reconductoring
Network Reconductoring is replacement of the existing conductor on the-feeder.with
optimal conductor size for optimal length of the feeder. This scheme arises where
existing conductor is no more optimal due to rapid load growth. This is particularly
relevant to developing countries, where annual growth rates are high and the conductor
sizes are chosen to minimize the initial capital investment. Studies of several
distribution feeders indicate that the looses in the first few main sections (4 to 5 say)
from source constitute a major part of the losses in the feeder and by reinforcing these.
sections with conductor of optimal size, the losses can minimize the total cost, that is,
cost of investment and cost of energy losses over a period of 5 to 10 years.
Rule-Based Optimal Integrated Strategy
Based on the investigations made on several practical distributions feeders and
‘considering the’ inherent characteristics of short term strategies the following
observations are focused:
1.
Reconfiguration among feedersis effective onlyif there is unequal loading amongthe feeders of the network. Reconfiguration within the feeder is dependent upon
the structure of feeder.The Network Reconfiguration is cost effective, as the rate of
return is high. It should be the first choice, as it improves the utility of other shortterm measures.
2.
Shunt compensation reduces losses to the extent of 40% to 60%,. if the power
factor is low (lower than 0.8). It also reduces the loading on feeder sections and
thus may avoid reconductoring. - The voltage improvement due to shunt
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compensation is marginal except in cas
e of very heavily loaded feeders. Shunt
compensation alone cannot correct volt
age drop.
3.. Reconductoring of feeders reduces
both losses and voltage drop when the init
ial
sections of feeder are loaded beyond eco
nomic or break even loading limits. The
existing supports generally have no stre
ngth to carry heavier conductor size and
may need reelection of feeders or insertio
n of intermediate supports. This measur
e
may Cause some difficulties in implementati
on in practice.
4. AVB reduces the voltage drop by
10% and is very effective tool to solve
voltage
drop problem. The reduction of losses duet
o installation of AVBis marginal and as
such rate is poor.
5. Series capacitor performance is like
AVB with regard to LRVI problem.
limited. Further, series Capacitor requires
elaborate protection andis costlier than
AVB
and thusit is not cost effective. It is ane
ffective solution, only when the loads are
of
rapidly fluctuating type. Henceit is not
recommended to tackle the LRVI proble
m of
primary network.
‘A Rigorous Mathematical Model, which
integrates all of the Strategies into one stag
e,is
complex andis difficult to solve using
optimization techniques. Hence a set
of rules
based on the investigations of several
practical distribution feeders to solve
LRVI
problem is suggested. The rules can
be formulated in the form of expert syst
ems.
Since rigorous optimization techniques are
employed for the solution of each short-te
rm
Rule-1: Check the loading on the feedersi
n the network. IF the feeders are unequall
y
loaded viz., some feeders are heavily load
ed compared to others, then reconfigure
the
networkfor minimal losses. Otherwise, go
to Rule-2. The above measure automaticall
y
-equalizes the loading on the feeders. The
n check for losses and voltage drop. If
the
target values for any feeder are not achi
eved, go to Rule-2.
Rule-2:
Check the powerfactor of the feeders.
IF it is below 0.95, determine the
optimal number, location and ‘Capacity of
the shunt capacitor banks to be placed on
the
network. Otherwise go to Rule-3. Check
losses and voltage drop andif violated go
to
~Rule-3. .
Rule-3: Checkviolation of which targets
comparatively severe. If voltage drop viol
ation
is Severe and losses are violated marg
inally, then install AVB on the feeders
to
improve .
voltage profile and maximize loss redu
ction. If loss violation severe and volt
age
violation is marginal proceed for re-condu
ctoring.
MAINTENANCE SCHEDULEOF DISTRIBUTION TRA
NSF
ORMERS
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1.__|
Cleaning of bushing and external surface of tank coiling pipes
2.__|
3.
Checking ofoil levels in the conservator and gauge glass
Checkingof silicased in the breather and replacementis necessary
Monthly
4.
5.
Checking of oil level in the oil seal of breather & top upif necessary
Checking of HG fuse & L.T fuse and renew if necessary (correct
gauge shall be maintained) checking breaker operation in case of
CSPtransformer
6.
Checking of vent pipe diaphragm
7.
Checking of terminal loose connections is any and tightening the
same
8.
Checking for anyoil leaks & rectification (including replacementofoil
seals if required)
9.
Taking tong tester reading during peak load hours and remedial
action wheneverload exceeds 80% rated capacity
10. Noting down neutral currents and load balancing in all the three
| Monthly
Monthly
Monthly
Monthly
Monihly
Monthly
Monthly
Quarterly
Quarterly
phase
11. | Measurementof IR values —
12. Testing of oil for BDV, acidity
13.| Checking of lightening arrestors and replacement is required
Half yearly
Half yearly
Half yearly.
preferably once before monsoon
14.
| 15.
Measurement of earth resistance checking of earth in system and
rectification if required
Overhaul of transformer
Half yearly
One in
years
5
MAINTENANCE SCHEDULE OF FOR POWER TRANSFORMERS
1.
2.
3.
“_ |
4.
Checking the color of silicagel in the breather and also oil Daily
level of the oil seal. If silicagel color changes from blue to
pink by 50%the silicagelis to be reconditioned or replaced.
;
Observation of oil levels in. (a) main conservator tank (b) Daily
OLTC conservator (c) bushings and examining foroil-leaks
if any from the transformer
| Visual check for overheating if any at terminal connections Daily in each shift
(red hots) and observation for any unusualinternal noises.
9.
Checking for noise, vibration or any abnormality in cooling
fans & oil pumps of power transformers standby pumps &
fans are also to be run condtion to be observed .
Observation of oil and winding temperatures and recording
Hourly
6.__|
Visual check of explosion vent diaphragm for any cracks
Daily
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7.
,
Checking for any water leakage into cooler in case
of Daily
forced cooling system
| 8.
Physical examinationof diaphragm for any cracks
9.
.
B8est Practices in Distribution Loss Reduction
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Monthly
Cleaning of bushings, inspect for any cracks or chippings of
Monthly
the porcelain and checking of tightness of clamps and
jumpers
10. Measurement of I.R valuesof transformer with 2.5
KV Monthly
megger upto 33 KV rating and 5.0 KV megger above 33 KV
rating. Recording of the values specify the temperature
which measurementsare taken.
11. Cleaning of Silicagel breather
Monthly
| 12. Checking of temperature alarms by shorting conta
cts by Monthly
operating the knob.
| 13. Testing of main tankoil for BDV and moisture conte
nt
Quarterly
14. Testing OLTC oil for BDV and moisture content
Quarterly
15. Testing of Bucholtz surge relays & low oil level trips
for Quarterly
correct operation
16. Checking auto start of cooling fans and pumps
17.
Quarterly
Checking of operation of bucholtz relay for any
gas
Quarterly /
ensuring actuation alarm andtrip
shutdown
collection and testing the gas collected
during fault
Checking of operation of bucholtz relay by air injection
Half
yearly
18.
19.
/
Noting the oil level in the inspection glass of bucholtz relay
Monthly
and arresting of oil leakages if any
Checking of all connection on the transformerfor tightness
Quarterly
20.
such as bushing, tankearth connection
"
21. Lubricating/Greasing all moving parts of OLTC mechanis
m
22. Checking of control circuiting, interlocks of oil pumps
and
,
Quarterly
cooling fans for auto start and stop operation at correc
t
23.
24.
| 25.
temperatures and also for manual operation
Testing of motors, pumps and calibrating gauge
Pressure testing ofoil coolers
‘
Testing of oil samples for dissolved gas analysis (for 100
| MVAtransformers)
.
Half yearly
Half yearly
Half yearly
26. Testing of oil for dissolved gas analysis EHV trans
former | Once in year
27.
upto 100 KVA capacity
Overhauling or oi! pumps and their motors also cooling
fans
Oncein year
and their motors
28. Testing of oil in main tank for acidity, tan delta, interf
ace Oncein year
tension specific resistively
29. Bushing testing for tan delta
Oncein year
30.
31.
Calibration of oil & winding temperature indicators
Repeates
Measurement of magnetizing current at normap tap
and | Oncein year
extremetaps
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32. Measurement of D.C winding resistance
33. Turns ratio at all taps
34. inspection of OLTC mechanism and contacts its divertor
|switch .
| 35. Overhaul of tap changer and mechanism
36. Replacementof oil in OLTC
37. Calibration of thermometers (temperature indicators) and
tap position indicator
38. Remaining old oil in thermometer pockets, cleaning the
pockets and filling with new oil
39. Checking oil in the air cell (for transformers of 100 MVA &
40.
above capacity)
Bushing partial discharge test and capacitance (EHV
transformers)
41. Filteration of oil/replacementof oil andfiltration
Once in year
Once in. year
Once in year
Oncein year
Oncein year
Yearly
Yearly
Yearly
Once in 5 years
Whenever
values
the
transformer
42.
IR
of
are
below limits.
General overhaul (consisting) (1) Inspection of core & Oncein 10 years
winding (2) Through washing of windings (3) Core
tightening (4) Check-up of core bolt insulation (5)
replacementof gaskets (6) Overhaul of OLTC
SHUNT & SERIES CAPACITORS
The type of usage have different applications, operation problems which are as.
discussed below:
Shunt Capacitors
Series Capacitors
1. Supply fixed amountof reactive powerto 1.
Quantum
of
compensation
is
the system at the point where they are dependent
on
load
current
and
installed. Its effect if felt in the circuit from instaneous changes occur. lts effect is
the location towards source> only.
from its location towards load end.
2. Causes reduction in reactive power
following in the line and causes (a)
Improvement of Power factor of system (b)
Voltage profile improvement. (c) Decrease
KVA loading on source (i.e.) generators,
transformers and line upto location and thus
provide additional capacity.
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2. It is effective
(a) On radial feedes improve
regulation,
automatically. (b) On tie lines; power
transfers are greater. (c) Specifically
suitable when flickers due to respective
load functions occur.
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|3. The location has to be as near the load
point as possible. In practice due to high
compensation
required - it
is
found 3. As a thumb rule, best location is 1/3"
economical to provide group compensation electrical imped
ance from source bus.
on lines and at S.S.
,
4. As fixed KVARis suppliedthis may some
/times result in over compensation during
light
load
period.
Switched
banks, 4. As full load current is to pass through;
comparatively costlier becomes necessary.
the capacity (current rating) should be
more than the load current.
5. As series capacitors feed faults also
special protection is required
5. As the power factor approaches unity,
larger compensation is required for
incremental improvement of power factor.
6. Causes sudden rise in voltage at its
| location.
/6. Where lines are heavily loaded
compensation required will be more.
-f. Cost of series capacitor is higher than
shunt capacitor.
¢. Cost is lesser compensation to series
8. Transformers draw high transient exciting
current when charged and this causes Ferro
resonance. Spark gap of capacitor to take
care ofthe contingency.
9.
capacitor.
Due to sub synchronous resonance;
motors when started through series
Capacitors, may get locked in and continue
to rotate at low speed. This is prevented by
providing resistor in parallel across
capacitors or resistor in series with supply
leads to motorat the timeof starting.
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TRAINING PROGRAM
BEST PRACTICESIN DISTRIBUTION LOSS REDUCTION
Distribution System Planning, Analysis, and Design
Prepared by Energy Economyand Environmental Consultants
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Distribution System Planning, Analysis, and Design
-
Energy Economy & Environmental Consultants
1. introduction
Electric utilities in India are facing the pressure of reducing costs and improving the
quality and reliability of supply. Though the Generation and transmission systems have
“VVVVW
seen considerable technical development and capital investment, the distribution and to
" some extent the sub-transmission systems have been neglected and have suffered due
to poor operating efficiencies leading to financial losses and cynical customer
perception. The distribution systems have suffered mainly from the following maladies:
Unbalanced Load Flow
Poor voitage regulation
High level of Technical (Peak power/Energy losses)
Conductor Heating / Equipment Damages
Very high unaccounted energy losses [20-40% againstinternational standards of810%}
Acute need for a consistent and Long lasting solution aimed at Improving &
Strengthening of the PowerDistribution network with minimum losses in the long run
through Integrated planning for PowerDistribution system has beenfelt for a long time
now.
Arising from these issues, the realization by the Utilities and the increasing reliance on
having accurate up-to-date information for decisions on increasing revenues, improving.
‘customer service and development is now setting in. Thankfully, there is now the
awarenessthat this approachwill be driven by modern
n technology.
For fast, accurate and-reliable data management, a power distribution software solution
based on an integration of dedicated GIS and Load flow analysis (viz., network analysis)
solution will provide the right kind of approach for addressing the issues affecting the
~ system. The advantagesof this approach are innumerable.
> Visualisation: Can visualise the actual network, asit will be laid out on ground.
> Convenience: Userfriendly and ease of data entry.
> Flexibility: Flexibility of choosing what other systems to share or exchangdata with
(i.e. Network Analysis, Inventory, Trouble call analysis)
> Better comprehension
A detailed description of the GIS, the processes involved and the applications are
discussed henceforth.
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2. Background ~
VVVVVVVVVVV VV
2.1 Present NeedsofDistribution Companyto achieve effectiveness
The present day Distribution companies haveto deal with a number of
problems &
issues to meet the day to day requirementsof the power consumers. Someof
these are
as follows.
System managementfor quality power with minimum tosses
Efficient diagnosis of losses - Technical & Commercial
Monitoring of commercial losses due to
Malpractice
Defective metering
Lack of meters
Undisciplined meter reading
Effective Metering & Billing programme
An effective vigilance system
Prompt actionon meter readers observation
Optimum inventory management
Proper customer complaints & grievance system
Effective Man powerutilization
2.2 Challenges
In addition to meet the present day needsthe distribution companies have
to overcome
V
VVVWV
many challenges. These are
;
Nonavailability of network information/data base
Non existence of regular updating system
Non-availability of any specific manual
Non-availability of any IT enabled tool to provide requisite analytical reports
correctly & quickly
a
The distribution company cannot work efficiently and economically Without
VV
availability of consumerand technical data base
Record day to day change in the system.
Analysis & improvementof the system will not be possible.
_2.3Solution - GIS data base & Distribution Analysis Software Packa
ge
The need of the hours is a powerdistribution software solution based on an integrat
ion
of dedicated GIS and Loadflow analysis (viz., network analysis) solution will provide
the
right kind of approach for addressing the issues affecting the system. The advant
ages
of this approach are innumerable.
> Visualization: Can visualize the actual network,asit will be laid out on
ground.
> Convenience:Userfriendly and ease of data entry.
@
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> Flexibility: Flexibility of choosing what other systems to share or exchange data with
(i.e. Network Analysis, Inventory, Trouble call analysis)
>» Better comprehension
The primary objective of using GPS and GIS for powerutilities should be to enhance the
efficiency of transmission/ distribution system in term of quality of power and increased
revenue earning by reducing T & D losses (both technical and Commercial), outages
and to merge the functions of independent offices into the main stream operational
hierarchy with the help of organization wide networking.
2.4GIS Applications
VVVVVVVVVY
GIS can be usedin distribution systems managementfor:
Handling customerinquiries
Fault Management
Routine maintenance can be planned.
Network extensions and optimization
Whatis analysis
‘Network reconfiguration
Improved revenue management
SCADAcan beintegrated with GIS
Rights of way and compensation
GIS environment hosts a wealth of presentation techniques that enable fast and
accurate interpretation of results from powerflow results to short circuit analysis.
2.5GIS Benefits
VVVVVVWV
Properselection & implementation of GIS will he the Distribution Company to reap the
following benefits
Improving financial viability
Reduction of T & D losses to around approx 10%
Improving customer satisfaction
Increasingreliability of power supply
improving quality of supply
Systems approachwith GIS
Transparency through Computerization
3. GIS Technology
3.1 Definition of GIS
GIS technology helps to
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MINISTRY 0
> Integrates common database operatio
ns (data query and Statistical analysis),
with the unique benefits of visualization
and conceptual spatial analysis, offered
by maps.
» Optimizes data layering (spa.tial overlays|
for object relationshipidentification),
> Allo
wsfor effective and
VVVVWV
3.2 Whatis the Need
In the present context, the GIS need to do
the following basic functions
Inventory of Existing Network
Easy access to Network details
_Easy access to Consumer Data
Data export for Analysis & Network Improv
ement of existing system
Load growth projections
3.3GIS components
The GIS consists of following component
s
1. Database — for storage & retrieval of info
rmation
2. Base map — for Geo referencing netw
ork system
3. GPS points — for picking up actual
location (latitud
e/longitude) of various network
components
4. User interface — foraccomplishing vari
ous tasks of reports, query, analysis
3.4GIS based mappingforelectrical net
work
All GIS data are made of two component
s:
1. Geomeiry of geographical features
like locality boundary, street bounda
ry, plot
boundary, building features
, etc. These type of data are called the "ge
ometric data".
This could be one or both of the follow
ing:
,
> Geo-reference satellite imagery pro
cured from NRSA or any other nodal
agency
> Surveyof India Maps
The geometric data is usually acquired with
one of the following two accuracies:
Coarse
Mapping
Fine
Mapping
Positional Accuracy
Geometric Tolerance
10m (using hand held DGPS or 1-2m
(using Rodometer
IKONOS).
Tape)
2m (using Geodetic GPS and Sub-de
cimeter (using ETS)
ETS)
:
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> “Fine Mapping" is much more capital intensive than "Coarse Mapping”.
> "Fine Mapping" is more laborintensive than "Coarse Mapping". >» Hence, "Fine Mapping” is usually two to three times as expensive as "Coarse
Mapping".
_
World over, it is the general practice to use "Coarse Mapping" specifications at the
planning stage.
2. Information associated with the geometric data like locality name, street name,
nature of occupation of a plot, elevations, etc. We will call this the "attribute data”viz.
Consumerdata
Category wise number of consumer and connected load including the Bulk
Consumerdetails such as
> Contract demand
> Maximum demand
> Energy Consumption
> ‘Supply Voltage
Demand data
,
-
> Peak demand MW/MVAR-simuitaneous and non simultaneous
> Annual Energy Consumption data
Network data
> Source (s) of power supply/Grid substation (s) supplying powerto the area
> Existing Substation
> Existing lines
Sub-Transmission System
> Existing 66-33/11 kV Sub-Stations & Existing 66-33 kV LINES.
> Under Construction Sub-Station.
> Under Construction 66/33/11 kV lines.
Distribution System
> 11kVlines
> Distributiontransformers
> LT lines
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Figure 1: Attributes for HT,LT lines
tists
VVVVWV
‘Operational parameters | Substation equipmentstatus
66/33 kV Feeder breakdowns
Failure of distribution transformers
Tripping on 11 KV feeders/lines
Consumer outages
Electrical network details
> Electrical network details - single line diagrams
with conductor sizes, lengths,
transformerlocat
ions, Capacitors, capacitors, consumer loca
tion andload etc.
> Parameters of equipments, devices and
conductors
» Load data-peak load, diversity factor, powerfac
tor etc.
Figure 2: Details of a distribution transformer
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LT Network
> Section length
|
> Conductor size of each section
> Connected load for each group of consumer
> Numberof consumers in each group
> Total connected load on the transformer
Equipment Parameter Data
The Schematic diagram for existing sub-stations are to be prepared with ~
information of power transformer rating and numbers, impedance values, bus bar
scheme, isolators, circuit breakers type e.g. minimum oil/bulk oil/SF6//accum
and type ofinstallation (indoor/outdoor), no of incoming and outgoing feeders,
CTs and PTs, details of taps and normal tap position, spare bays etc.
VVVV
WV
Load DataThe load data covering the monthly, daily and yearly details of energy/peak
powerin the electrical system as well as information as below is required:
Peak load on each transformer/feeder and corresponding actualvoltage.
Diversity factor at various voltagelevels.
Powerfactor at various voltage levels
Load factor and loss load factor at various voltage levels.
Finally, Plot the above points of entities on the digitized maps. Model the network using
a network mapping software and build customized queries on network database.
3.5 Preparation of GIS
Geographic Information Systems is a
system of mapping of complete
electrical network. including low voltage system and customer supply points
with latitude and longitudesoverlaid on
. Satellite imaging and/or survey of India
maps.
Layers
of
information
are
contained
in
° these
~ map
representations.
The
first
layer
correspondsto the distribution network
coverage.
The
second
layer
corresponds to the land background
containing roads, landmarks, buildings,
rivers, railway crossings etc. The next
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layer could contain equipment information
viz poles, conductors transformers etc. Most
.
of the electrical network/equipment have
a geographical location and the full bene
fit of
any network improvement can be had
onlyif the work is carried out in the geog
raphical
context. The “attribute data” is attach
ed to each of the entities using a bac
kend
“database”,
3.6GIS Applications
3.6.1. Querying a GIS
Interfaces that use the querying facility
available with the RDBMSin the netw
orkmapping environment will provide the
accurate and reliable information to the
utili
ty
operational staff on the spatial and nonspatial attribute data of the network crea
ted in
the GIS. Customised interfaces can be deli
vered as also the staff can be easily trai
ned
3.6.2 Maintenance & Monitoring
Let us assumethat the engineer has to
send a cable jointer in the field who has
to
access a certain underground cable joint.
The engineer can take the digitized mapf
ile
of
the area, mark a small portion of that area
in the neighborhood ofthejoint, and print
that
small part on a piece of paper. This prin
ted map of that small area will show, to
the
jointer, the location of the joint with
proper distance and bearing referenc
es to the
nearby identifiable objects. With
these references so readily available with
the jointer,
his work will be easy and quick. There will
be no need for him to have any guesswork
or
to constantly contact the office for knowin
g the joint location.
3.6.3 Information Processing
Information processing is a key to imp
rove productivity and cutting costs of
excess
work. Converting information to a com
puterized format in GIS is more usef
ul and timely
for electric utility. For example: GIS will
allow to search and retrieve information
stored
on a server simply by pointing and clic
king through user-friendly menus or typi
ng
Tequesis in a Windows environment.
GIS has a way of making work proces
ses
simp
ler
through moreproductive use of time and
information.
The applications of GIS with respect to urban & rural
area is given below.
Urban:
> Consumer indexing
> Asset Management
> Location offaults
> Efficient planning of maintenance
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> Effective network augmentation/upgradation
> Customer Management viz. Complaints, new services, etc
> Build in consumerdata base covering consumption, billing and collections, etc
> Energy Audit& MIS —
.
VVVVVWV
Rural:
Asset Management
Efficient planning of maintenance
Location of faults
Effective network augmentation/upgradation
Monitoring of consumption
Energy Audit & MIS reports
4. Software based distribution network analysis
4.1 Whatis the need?
Improving the performance of Transmission & Distribution systems to meet required
targets is a matter of..selecting the most cost-effective technologies and operating
practices. Particularly the distribution systems tend to be very extensive with a longlife
span for conductors andplant. It is not sufficient to analyse how a particular portion of
the network may be modified to improve its performance today: it is a matter of
determining what would be the optimal solution when allowance has also to be made for
the uncertainties in the prediction of the future scenario of customer demand. It is
valuable to investigate long-term solutions specially so when the implementation of the
solutions will also entail decisions involving large-scale investments.
VVV
VV
-The systematic and methodical approach to planning, design, construction, operation
and maintenance ofdistribution systems using Computer aided tools should be adopted’
by the utilities for upgradation of Transmission and Distribution system.
.Assessmentof Voltage Regulation .
Peak Power Loss/Energy Loss of each system élementto arrive at total technical
loss
Assessmentof inadequacies of the existing ST&Dsystem
Inadequacy of the backup transmission system
Security and reliability of the power supply
.
i
.
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4.2 What does it provide?
[
Y
Network
Creation
_
Analysis
y
System
-— Analysis
a
SLD
|
v
System
Optimization
Geographic
Cost benefit
Analysis
What if analysis
Express feeder
HVDS
Reconductoring
r
Switch optimization
Network
reconfiguration
representation
Capacitor
Over load cquip.
Equipments
Veasibitity
Sub station design |
Reconductoring
v
Reports
Transformer summary
Consumer summary
Energy Audit
an flow
ort circuit
Complaints
Inventory
Others:
Consumerledger
Load Balancing
Consumerservice losses
Shortcircuit
> Load flow
Net work configuration. .
VVVVVWV
4.3 Advantages of software based network analysis
The following are the advantages ofthe software based
network analysis
Very accurate analysis of Voltage variation, Energy loss,
etc
Less time requirement
Graphical output Quick Output based onquery for each facility/line
WhatIf analysis
‘Manual method - More possibilities for error and
Time consuming process
Labor
ious method
>
4.4|ntegration of GIS & Network analysis systems
“GIS” and “Network analysis Systems” for Electr
icity Distribution Utilities provide
differ
ent sets of information. GIS provides static information related
to the location and attribute related data of the assets installed in the field. Netwo
rk Analysis, on the other
hand, is an engineering application, which is independentof
the equipmentlocation and
provides dynamic information related to the performanc
e of the network. The network
performance is computed by using equipment related physi
cal parameters and other
engineering data of the supply network. When viewed
separately, if one were to
conclude that these two
are independent systems with no commonality betw
een them,
one would not’be grossly wrong. However, a close view.w
ill indicate that both these
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systems since are somewhatinter-related they are usefulto the utility in their own ways.
Therefore, it would be preferable and advantageousif they could be combined into one
as an integrated system. Such integration will allow the utility to share, between these
two systems, the data and information common to both. And,.as a result, the utility
would save considerableefforts and. money to implement, use, and maintain these two
as separate systems.
5. Software Analysis Methodology
VVVVV
The major components of software based networkanalysis includes
Mapping of the Network
Information aboutfacilities
Loads
Analysis
Output
5.1 Mapping of the network:
Most of the electrical network/equipment -have a geographical location and the full
benefit of any network improvement can be plannedonly if the work is carried out in the
geographical context. The basic geographical land use maps should be prepared to
scale in the second phase. This can be done by importing the GPS based Networks
with actual lengths of each span, load centres, transformerpoints, etc into the software.
Alternately the software can be clubbed with a GIS backend to collect information of
network & its assets.
’
5.2 Information aboutfacilities
“In the beginning sample LV network emanating from distribution transformer located in
high, medium and low load density pockets of the circle and covering different
categories of consumers may bemodeled whichcanform thebasis for determining the
;
improvement in’ the entire LV »
network. The following information
is essential for modeling of. the
"
Section length
.Conductor size of each section
Conductor type
Vv
Connected load for each group
of consumer
Number of consumers in each
Vv
WVYVYV
low-voltage network.
group
Total connected load on the
transformer
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5.3Loads
VVV
Wv
Thereliability of analysis results depends on
the quality of input. The load data should
cover the monthly, daily and hourly details of
energy/peak power in theelectrical system
of the circle. The load data could be obtained
from the log sheets maintained at each
33/11 kV sub-station. The data could also
be obtained more accurately from logging
type electronic energy meters, if available in
the system. Lot of care has to be taken to
provide thefollowing inputs
Load of each consumer
Transformer load — Peak load on each tran
sformer/feeder and corresponding actual
voltage
PowerFactor(PF) at various voltage levels
Power & Energyflow at the Input buses on
the network
Actualvoltage levels at the input bus
The steps 4.1 through 4.3 can be avoided
through integration of “GIS” with “Network
analysis software”.
5.4 Analysis
VVVVVVVVVVVVV
After providing necessary inputs, the software
can be asked to perform analysis for the
following:
Load flow study
Short circuit analysis
What if analysis
Over loaded equipmentanalysis
Network reconfiguration
Switching optimization
Load balancing
Energy auditing
“-HVDS
Reconductoring
Capacitor placement
Express feeder proposal
Protective device coordination
5.5 Output
The output of the analysis will be given in a
summary format/ graphical view
1. Summary/Text Output
>» Based on the queries specific reports
on voltage regulation, loss level, loading
levels can be obta
ined
» Segregation of losses at various voltages
and into categories
> Identification of causes leading to Higher
Losses
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> Estimation of benefits from various improvement options to choose the best
option
2. Graphical output
A series of graphical output examplés depicting the analysis of a distribution. network
before and after carrying out some modifications is given. The graphical display
provides information on improvementin voltage levels pre & post modifications.
The following figures show the “before” & “after” cases for Voltage profile while studying
the modifications under “Express feeder” & “High Voltage Distribution System” for a
11kV feeder.
It can be observed from the following ‘three figures that the overall losses can be
reduced to 193kW from 749kW by adopting HVDS system. The result of this is also
reflected in the voltage profile where almostall the segments are in the range 90-100%.
Figure 3: Voltage profile of 11kV feeder
Red © 1350- 70%
Yellow : 70-80% ~
Magenta: 80 - 90%
:90 = 100%:
_*MajorLosses in the Trunk section
“Excessive voltage dropin HTitself
“Very. Low ‘voltage level-in.LT‘Section
*Total: losses 749.kW
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Figure 4: Voltage profile after “Express feeder” modification
i}
ddsciate Group it View]
mptoveren in HT Voltage even attai ‘end
‘Marginaliimprovementin LT-voltagelevel .
*Total Losses reduced to. 594KW... os
:
3
oe
Figure 5: Voltage profile after "High Voltage Distribution System"
SYNerGEE. [International Resources Group Map View]
° Improvementin LT voltage level ,
rota losses1reduced to 193 kW
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6. GIS Based Growth Planning & Load Forecast Implications
6.1 Whatis the need?
For the Distribution system planning which involvessiting of substations, routing of
feeders and many other decisions relating to both locations and quantum of capacity
additions, the forecast of Geographical locations as well as quantum of future load
growth is necessary.
6.2 Whatis GIS based?
Load forecast of Geographical locations as well as quantum of future load growth can
be easily made using GIS and also the planning of Distribution system like
upgradation/strengthening can be performed accurately with the geographical, and
networkdetails with consumptionhistory is available in the GIS.
6.3 Load forecasting .
The Distribution system planning involves siting of substations, routing of feeders and
many other decisions relating to both locations and amounts of capacity additions.
Therefore, the Distribution load forecast refers to forecast of geographical locations as
. well as quantum of future load growth. The three step procedure for Distribution load
s. forecastis:
*. 1. Trend Analysis- analysis of past trends of growth in electricity demand. and energy
~ consumption
.
.
2. System load forecast viz. Forecasts of load for the entire study area
3. Spatial or small area load forecast viz. Divide the utility service area into sufficiently
‘large numberof small-areas and forecast for each small area
6.3.1 Trend analysis
Trendsin electricity demand plays a significant role in the forecast of future demandif
the area is already exposed io electrical power usage and past records are available.
The data required for trend analysis is Category wise numberof services, Connected
load and Energy consumption for the last 5 to 10 years, etc. These parameters can be
,
incorporated in GIS for Trend analysis.
The important trend parameters evaluated from analysis of load growth are:
> Growth rate of energy - year wise and cumulative growth rate of energy for the
period
So
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Share of electrical energy consumption among different sectors year wise and
the
average for the period
Energy consumption per service year wise and the average for the period
Growth rate of service connections year wise and cumulative growth rate for
the
Vv
period
Connected load per service connection year wise and the average during the period
6.3.2 System load forecast techniques
System load forecast techniques can be broadly classified into three categories:
1. Techniques Based on Extrapolation : This technique involves fitting a trend curve
to
the basic historical data, using method of least squares
2. Techniques Based on Co-relation: Relates the system demand to various
demographic and economic factors such as population, value added, net
domestic
product, etc.
3. End use Method: Demand of each category of consumeris assessed and summe
d
up to arrive at total consumption. Generally this method is adopted for distribu
tion
systems.
6.3.3 Spatial load forecast
_ The forecast of loads and their locations, known as spatial or small area
load forecast,
is very importantfor Distribution system planning. For optimal siting of new substat
ions/
augmentation of capacity of existing system and economical reinforcement of
existing
networks, the spatial load forecast has to be adopted.
For this purpose, total area is divided into a number of small areas and the
loadsin
each area are forecasted.
> Constitution of small areas:
_» Grid co-ordinate system - for urba n areas
‘> Random area method - rural area
Objective of spatial load forecast is to allocate among the small areas the
growth of
demand or energy consumption/number of customers computed in system forecas
t for
the total area
.
6.4End use method
The demand for energy is estimated for each category of consumption taking
into
account relevant parameters such as
> No. of consumers
> Connected load
» Annual rate of energy consumption per consumer |
> Past trends, etc
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> Peak demand is worked out from total consumption adopting appropriate load
factors keeping in view the nature and composition of loads and considering the loss
figures.
6.4.1. Estimation of Agricultural Consumption/Rural Load
Main factors contributing to load growth in this sector are:
> Potential for tapping ground water /lifting it from a flow of stream
> Development of other allied agricultural activities like horticulture, forestry, fishery
and
> Potential for development of agro-based industries and ongoing programmes of
other development agencies for boring of well and / of energisation of pump sets
Agricultural consumers are largely unmetered & a. correct assessment of energy
consumptionis also very difficult
Agricultural consumption mainly depends on
>» Number of Pumpsets
> Capacity of Pumpset
> Numberof working hours.per day
The number of Pumpsets and their capacity are
e grossly underestimated, as there are
number of unauthorized Pumpsets and the capacity of the motor is increased due to
depleting watertable.
:
VVVVVVVVV
The number of working hours depends on:
Areairrigated.
Types of crops grown
Ground waterlevel
No. of crops grown/annum .
Yield of well
Rainfall in the year
Type of soil
Seasonal requirement
Availability of power supply
6.4.2 Methods to assess Agricultural Consumption
The data on these factors is not being maintained by any single Government
Department or agency. Hence mostof the utilities have been assessing a uniform figure
for the entire state for number of hours a pumpset works in a year based onfield
assessment. The methods. which are being used to assess agricultural consumption
are:
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VVV
Sampling - Avg. consumption per HP from
sampling techniques
Annual Load Factor- Avg. Load Factor x Tota
l kW of pumpsets x 8760
Consumption /irrigation/hectare as per
studies by independent agencies. Consumption for one irrigation/ hectare x
No. of irrigation/year x Total land under
irrigation.
>» Comparing with State Tubewell/Corpora
tion Tubewell Consumption Data
6.5Planning Objective
Objective of strengthening and improveme
nt of ST&D is
» To ensure quality and reliability of supp
ly to consumers
> Bring down technical losses to an opti
mal value and
» Phase the system expansion to match
the demand growthin the time horizon of
the
study
6.6 Planning Philosophy
Approach for Planning ofdistribution syst
em. should be based on: .
.
> Delivering bulk supply of electricity as
near to the load centres as possible
» Consumers affected due to outage
to be few in the area, if at all it bec
omes
inevitable
> Formation ofring circuit and radial circu
it or combination of both, depending on
the
technical and economic requirement of
the system to enhance reliability of pow
er
supply
.
s
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=
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Voltage regulation
s
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VVVVVVVVVV VV Vv +
6.7 Planning Criteria
Siting of Primary substation
Capacities of Power & Distribution transformers
Choice of conductor
11kV feeder design .__ ce
Selection of voltage vis a vis size of cond
uctor
Customer substation
Power Factor
Technical loss levels
Maxfault levels
Harmonic distortion
Sub-station layout
Distribution automation.
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6.8GIS based planning
GIS
Planning
¢
Load Forecast Techniques
—>
—_—|
Distribution Analysis
Software
Long
term
Upgradation of Sub-transmission & Distribution systems
_ Based on the Demand Growth, the planning for the upgradation of ST&D system should
be performed
Sub-Transmission system requirement:
> Augmentation of sub-stations
> New Sub-stations
> Sub-transmission lines (new)
> Reconductoring of sub-transmission lines
6.9Short term options
VV VV
In the short term, the results of the analysis would be used for estimation of baselevel
technical losses, and for segregating the total unaccounted losses of the system,
available from the energy balance into technical losses and the non-technical i.e.
commercial losses (occurring mainly due to faulty /ampered metered supplies, due to
the illegal connections, due to powerdelivery atflat rate to the subsidized category of
consumers).. Besides, extrapolation of the results of the analysis of a sample fow .
voltage (0.4 kV) network for the complete low voltage network will also be done. The
technical power loss reduction will be accomplished by.the following measures:
> Network reconfiguration including installation of new primary and secondary substations/up-gradation of existing sub-stations
Newdistribution transformer sub-stations/up-gradation of distribution sub-stations.
Re-conductoring
Capacitor placement
Load balancing in the three--phase system
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MINISTRY 0
> Refurbishment/replacementof old and
obsolete equipment
The measureswill follow certain system
design philosophy that would be. decided
in
consultation with the customer €.9., prior
ity level of consumer in terms of service
availability, requirement of short-circui
t levels, level of redundancy required
etc. The
system improvement mea
sures will be applied to meet the spec
ified common
requirements, which would generally be foll
owed viz., Loadinglimits of conductors and
transformers, supply voltage variations with
in thelimits specified by the Indian Electricit
y
rules, targets for economic loss levels as per
CEA normsetc.
6.10
Long Term Options
In the long-term, due to the need to identify
and predict the customer demandsthat will
decide the system loading conditions prevaili
ng in future, outputs of the trend analysis of
load growth and load forecasting will be used
. The processofload forecasting based on
the trend analysis of past load growth, thou
gh complex, is invaluable in optimizing the
planning approach for the network expansio
n on a long-term basis. As stated above,
having a geographical reference for the netw
ork will provide necessary information. on
land use pattern for planning optimum expa
nsion of network and for setting up of new
facilities. The spatial load forecast meth
od, which divides the total area into num
ber of
small areas, with the specific growth rates
and the load characteristics applied to each
small area, is the ideal method for opti
mal planning of the distribution system
of the
area. For optimal location of new sub-stat
ions and augmentation of the existing
facilities, several alternatives, subject to their
meeting the agreed planning criteria, will
be evaluated on basis of the Capital cost ofe
quipment and work and net worth present
worth of the energy losses over the total hori
zon period. The plan objective will be the
minimization of losses whil
e maximizing the net benefit i.e.,
the present worth of loss
reduction less the annual cost of capital
investment. The cost estimates will be
based
on the prevailing market rates for each item
of equipment and work.
VVVV
vVvvVvVyY
A few long-term options are
Adoption of HVDS
Standardization of construction practices and
O&M procedures
Adoption ofDistribution Automations techniqu
es
Adoption of DSM measures
Use of electronic meters with remote
meter. reading systems, prepayment mete
rs,
etc.
Use ofall aluminum alloy conductors, AB
LTlinesin theft prone area, XLPE cables
Lowloss transformers
Ring main units, Automatic sectionalisers,
autoreclosers, load break switches, etc
Adoption of Management Information syst
ems, Customer Relationship managemen
t
systems, etc
.
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TRAINING PROGRAM
BEST PRACTICESIN DISTRIBUTION LOSS REDUCTION
Best Practices in Commercial Loss Reduction
by Kodanda R. Parupally, CORE international, Inc.
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BestPracticesin Distribution Loss Reduction
_ Distribution Reform, Upgrades and Management (DRUM) Training Program
Best Practices in Commercial Loss Reduction
Kodanda R. Parupally, COREInternational, Inc.
The study on commercial losses in powerdistribution utilities involves the following
-ON>
steps:
Direct tapping by the non customers.
Pilferage by the existing customers.
Defective metering, billing and collection functions, and
The role of franchisees, user groups and gram panchayats in billing and
collection.
Direct tapping by non customers
In certain areas, direct tapping of power by non customers is widely prevalent. This is
mainly in domestic and agricultural categories. Geographical remoteness, mass basis
for theft, poor law enforcement capability and inaction on the part of utility, are helping
this phenomenon.
Some amountof public relations work by the utility is needed to tackle this menace.It is
to be widely publicized that theft will increase the tariff for the genuine consumers, result
in poor voltages, burnt motors, failed transformers and dried crops. The scarce
resources of the state meant for social welfare are diverted to feed these powerthieves.
Somechange in the value systems of the society is also needed. The opinion makers
and social leaders are to be involved to effectively tackle this massivesocial evil.
Direct theft is an insult and thus a challenge to the utility engineer. It speaks volumes
about the inefficient functioning of the company. Tackling it brooks no delay. Other
works can be stopped andtotal attention divertedfor this purpose.
The details of legislation, procedure to inspect, detect and prosecute the criminals are
discussed separately.
Pilferage of powerbythe existing customers
Theft by the existing consumers is the predominant cause of loss of revenue tothe
electrical utilities. Almost all categories of the consumersare involved in this. However.
emphasis can be given on inspecting high value services for more effective and
immediate gains.
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The modus operandi
A.
Totally bypassing the meter.
The meter is not tampered. It is like direct tapping. From the supply lines, the tappingi
s
made andpart or full load is fed from that. This can be proved only whenit is observ
ed
at the time of inspection. The consumer can erase alltraces of theft if the inspecti
onis
knownin advance.
B.
Tampering the meter.
1. Bypassing at the terminal block.
2. Damaging the meterinternal mechanism.
There are umpteen methods for tampering the meter. New methods are
being
consiantly evolved. The thief is always ahead of the police. The latter tries
and
sometimes succeedsin catching the former.
a
The problem oftheft, its magnitude, procedural aspects in detecting it andlegal position
are discussed now in detail. Here, it is to be noted that these are commo
n for both
customer and non customertheft.
Tackling Power Theft
Genesis
Theft of energy is almost the single cause of all ailments afflicting powerutilities.
The
transformerfailures, breakdowns, poorcollection of revenue,financial losses,
the wide
spread customerdissatisfaction, the recurring crisis in summer crop period,
the poor.
creditworthiness resulting in inability to raise the funds needed for the required
growth,
increased technical losses and the corroded integrity of employees... are
all the
manifestations of the theft. These can include low frequency, cascade trippings
in: grid
and unscheduled shutdowns. The whole bad image of theutilities is due to theft.
In the
districts where theft is non existent, the utility is having good reputation and vice versa.
Magnitude
In the nation around Rs.40, 000 crores are lost by the utilities annually. In any
other
sector - be it private, public or joint - or beit in the state or the nation — no other
companyis losing moneyin this magnitude. In the world over powerutilities are making
' profits. Those shares are considered as retired people’s and widows’ shares.
They
make money whether it is famine orflood, though not excess profits. With just half
of
this amount employment guarantee schemeis being planned. Within two and half years
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of this money all the 444 pendingirrigation projects can be completed, irrigating millions
of acres.
Beneficiaries
The beneficiaries of theft are anti social elements, immoral political abettors and
unscrupulousindustrialists. The bad money is driving out the good money from the
market. This is a social menace crippling all other developmental and social welfare
activities.
Forerunner
A.P., as usual, is the forerunner in recognizing this menace and established a separate
wing for pilferage detection as early as in early sixties. Even now in somestates thereis
no such separate cadre for detecting pilferage. The local officer, either operation or
construction or MRT, is very much preoccupied with his busy day-to-day activities and cannot spare time for detection of theft. The social and political influences are
more easily brought on the local officer who has, perforce, to deal with them in
other fora regularly. A specialized knowledge on the functioning of various meters
and the latest M.O. of power theft can be acquired by a dedicated band only.- Personnel: While filling up DPE (Detection of Pilferage of Electricity) wing extra
care is to be taken so as to have only officers having the required technical
knowledge, tact, tenacity and integrity: at times, they would be detecting, dealing and
deciding the casesinvolving crores of rupees on the spot.
Opportune time: With the advent of E.R.C., the functioning of electrical utility is now
transparent. lts financial performance is in public gaze. The necessity of eradicating
theft is realized byall.
After realizing this, state governments are coming out in a big way to support the
electrical engineers entrusted with the arresting of powerpilferage. The opposition
parties, farmers’ organizations, colony welfare associations and industrialists are one
with us in this errand. If we do not move now, our very sincerity will be debated.
One cannot be guilty of inaction on the notion that attempting to control theft is
dangerousto onesself. Actually the test of ones loyalty to the organization is the
number of cases she booksin a month.
Functions: Though originally DPE- wing was meant only for detection of pilferage, of
late its functioning is covering many other facets:
1.
Malpractice.
2.
Backbilling.
3.
4.
5.
Excess connected loads.
Poor powerfactors in all categories.
Running of captive generator sets without adequate safety arrangements etc.
6.
Non sealing of AB switches, meter boxes, and terminal covers.
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7.
Line losses inselected towns, industrial feedersetc.
8.
Functioning of border meters, capacitor banksetc.
9.
Bus, P.T. and C.T.facilities for efficient metering.
10. Inspectionof high value UDC services.
11. Study of MRBs.
12. Applying CAT for HT & LT services and inspecting class F services,etc.
13. Maintenanceof assets by local officers.
14. Billing irregularities in transformer repairs, maintenance and construction
works.
15.
16.
17.
18.
19.
20.
Non standard releasing of services.
Releasing of services in UDC premises.
Releasing of services in wrong categories.
Coordinating massive inspections with all engineers and APTS personnel
whereverrequired.
Involvement of employeesin various irregularities.
Payment andbilling pattern of services of VIPs.
Legal Aspects:Electricity Act 2003 is being implemented now in respect of powertheft
and other irregularities.
The relevant sections with brief description are covered
separately.
,
Theft or pilferage of energy is a conscious and dishonest consumption of unmeter
ed
energy.
For backbilling and such cases where no prosecutionis contemplated, section 126 is
desirable. Where the loss to utility is heavy, section 135 is to be taken recourse
to and
otherwise section 138. Sections 135 and 138 are cognizable, nonbailable
and
punishable with imprisonment.
Judgementality. Understand the value systemsof the judiciary.
Let 99 criminals go scot-free, but one innocent person should not be convicted. So even
an iota of doubt will make the case weak. The beneficiary of the crime and the motive
are to be established convincingly. Above board. Notonly respect judiciary but seem to
respect too. Take the seat only when offered which is done fairly quickly. No
unnecessary laughing. Keep a smiling face and givefirm and polite replies.
Rapport: Meet the people of the area: in advance.’ Explain to them that the: theft
eradication is for their benefit. Higher tariffs, low voltages, drying crops, scarce
resources for social welfare and development, failed transformers and burnt motors
can
be avoided. Initially target the opinion makers who will set the trend for others to follow.
In some cases,attacking the weakest link may be taken recourse to. Prove that thieving
is not any more economical.
The arms and ammunition: Every engineer of utility, authorized to detect, must have
the following materials always with her:
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Inspection notes, white papers, carbons, stamp, stamp pad, gum bottle, cuiting pliers,
cutter, spanners of assorted sizes, tester, 1O00W heater, testing bulb, magnifying lens,
torch light, camera, cloth backed covers, meter cartons and a hammer. Seals, sealing
wire and sealing pliers are desirable.
,
Whereis theft? Contact your worker on one to one basis. He will come out. Explain to
him that if theft is detected subsequently by any inspecting officer, he has to explain his
ignorance lest he be impleaded as an abettor. If he points out some thefts, subsequent
one or two findings can always be explained. Meter reading register is the best source
to catch thieves. You go to a house, see the bill, connected load, the consumption
pattern and you can easily conclude. Give wide publicity to the phones of vigilance and
DPE officers. Once a message goes to the public that you are really serving your
organization, there would be a constantstream of revelations by the informants.
Reconnaissance: Select five to six targets in a locality. One person should know the
location precisely and he should take the inspecting officer to the installation directly.
The ownership, the name of the registered consumer, the name of person availing
supply and the No./S.F.No.of the house/field are to be collected in advance.
- Sensitive areas: The targets are to be finalized much in advance. The precise time of
raid shall be kept confidential. Go in required numbers. Small is beautiful. Mobility is
required. Get satisfied if you could detect one or two cases. Close the show in one or
two minutes. Inform all the members of the team, to come back to the vehicle in one
and a half minutes and there would be no waiting for them. To the extent possible, bring
the criminal along with you.
‘Sprinkle color; Take color photos of the scene and details of offence. Avoid private
photographer; he may decline to stand as a witness in the end. Have five copies of
each photo.
Furnish negatives to police.
Mark the particulars and if possible
signatures on the reverse of photo.
Writing notes:Fill up every item of the inspection notes. Note correct postal address.
Draw a sketch of the scene of offence on a separate sheet marking the orientation. Try
hard to.get signature of the consumer/representative. Procure independent witnesses
limiting to two. Even departmental witnesses should belimited to one or two. Theutility
‘cannot afford more witnesses. You lose the case by not being able to bring all the
witnessesat atime for the hearing and by not being coherent.The scene and method of crime should be noted clearly. Don't commit the details of
which you are not certain.
Police. They are there to protect law and orderandto lookafter all the teams. They are
not there in a single scene of offence from the beginning to the end. Theirnames are
not to be notedin the inspection notes.
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Seizure. The Act is emphatic on incriminating material. So
bring the materials, wire and
equipment to prove the crime. Note like this; ‘The servi
ce wire and the motor usedfor.
committing the pilferage are removed from the scene of
offence to hand over the same
in the police station for producing in the court as
material evidence’. Keep the
incriminating materials in a cover/carton,seal and haveit
attested byall.
F. I. R. Give the complaint as soon as possible.
Delay is dangerous.
In the
complaint you can add the names ofthe persons who are
actually committing/abetting
the crime. Narrate the whole event asit passed. Note
the taking of photos, removal of
incriminating material and hand over the same along with
complaint. On a separate
sheet, write downthefull name, age, profession and addre
ssofall the people involved
and give one copy fo S.H.O. On a small Slip, note downthe
details of crime, signatures
and pasteit to the removed material. Give extra slips to police
.
Court matters: calling out in a court is theinitial stage in
the day whenthe cases to be
actually taken up on that day are decided basing on
the presence of the persons
connected with the case. Crime No. is the number given to
a complaint registered in the
police station. Court Case No. (C. C. No.)/Original Suit
No.(O.S.No.) is theserial
numberof the case registered in the court initially. 1LA‘N
o. (Interlocutory Application
No.) is the numbergiven to an interim petition filed by eithe
r ofthe litigants in which one
seeks aninterim relief while the original case is yet pending.
W.P.No. (Writ Petition No.)
is the case number in high court. W.P.M_P. (Writ petiti
on miscellaneous petition) is
interlocutory application in W.P. IPC 186is for mere obstr
ucting the public servant and
is cognizable. IPC 353 is for obstructing the public serva
nt with force. It is bailable,
cognizable and can go upto 2 yearsorfine or both. IPC
332 is for major injury to public
servant. In
cognizable offence, police can arrest without warra
nt. Cr. P. C.
authorizesprivate personsto arrest the criminalsin certain
cases.
43
Rehearsal.
—_Oneday beforethetrial, collect the witnesses and recoll
ect the scene of
offence so that the actual incident can be presented to
the court accurately and with
coherence.
Ensure the
presence of other witnesses. Go through the file. Meet the
lawyers in advance andclear their doubts. Appeals are to
be madein time.
Suggestions:
Let there be frequent change of incumbents interacting
with the
consumers. A message should gofo every onein the socie
ty that theft would be curbed:
at any cost. Every officer should be made conscious of the
present policy of making him
accountable for the energy taken by him. A comparison
with contiguous areas will
highlight the weak spots. Any replacement of single phas
e meter shall be done only
after S.O. inspects, Asst. Divisional Engineer in case
of 3 phase meters. All removed
meters should .be handed over to M.R.T. It shall check
every meter for possible
tampering. Inaction-on the part of any field officer-in detec
ting cases shall be reviewed
and taken seriously. The theft is very predominantin many
areas. Single Section Officer
or handful of DPE officers can never complete the job.
Authorizing revenue and
police officials, as is done in. M_P.; to detecttheft is desir
able. Sub engineers and UDCs
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also can be authorized to book category | cases at least whenthere is no meteratall.
Elecironic meters will go a long way in controlling theft. Clear guidelines on the
procedure to be adopted, while releasing a new service, are to be issued.
MIS: The performance of DPE wing is to be reviewedperiodically as is done for other
wings. Their functioning in all the activities is to be taken into account. MIS reflecting the
performanceofan officer in controlling theft is to be insisted.
IT Applications: Of late, the rate of booking cases increased substantially. The
drudgery of paper work is appalling. No meaningful review and follow-up is becoming
possible manually. Marking of copies to various wings, communicating to them and
confirming subsequentactions manually is really meaningless in this age. So !.T. should
be brought in and made full use of. Already M.A.T.S. is being implemented in
Hyderabad company. This is to be studied and revised suitably and implemented
throughout. CAT is a useful tool for detection of theft before inspection.
Nemesis: Control of theft is not a single time operation. No amountof hi-tech gadgetry,
ABC, boxes to meters, theft-revealing meters - will serve any purpose unless they are
accompanied by continuous vigilance. Stop other work, if necessary, and rush for catching the thieves now!
Theft of energy and Electricity Act 2003
|.
Hl.
Electricity Act 2003 brought radical changesin all the facets of the electricity
sector. Let us consider its impact on power theft and assessment.
Sec.55 contemplates compulsory metering of all the services within 2 years.
Concerned E. R. C. is to initiate action on the defaulting company and person. It
can extend this period if necessary.
‘
_
lil.
,
Sec.126. Earlier, the litigation could be prolonged endlessly, Further there were
innumerable stages for appeal by the accused. Now they are reduced to just two.
a.
Inspecting officer.is herself the provisional assessing officer and acts as the
final assessing officer too.
b. This section is non criminal in nature.
c.
Assessmentis at one and haif times the normalrate.
d. The assessment is to be made for 3 months for domestic and agricultural
services and 6 monthsfor other services.
e. The consumer could always say that he-did not receive any notice from the
utility. Now the Act says that it could be served on any person available.
IV.
Sec.127. There is only one appeal. It is to be made within 30 days after making
one third payment. Earlier, there was protractedlitigation without any payment or
with nominal payment. After such long periods, interest too was not levied. This
section specifies 16% half yearly compoundedinterest after 30 days of order of
assessment and not from the date of serving of the notice. Further, the decision is
final.
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V.
Sec.135.
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Criminal
prosecution
is to
be
launched
DISHONELSTLYtaps, tampers, damagesetc.
a.
on
the
person
who
3 years imprisonment orfine or both can be levied. Forthe first offence
, the
fine is at 3 times the loss sustained by the utility. For the second
offence,it is
at 6 times andif the connected load is more than 10 kw, impris
onment is from
6 months to 5 years.
The burdenof proof rests on the consumer.
b.
c.
d.
The inspecting officer can break open, seize and remove records.
But the presence of one adult male memberof the family is necessary
p.m. to6 a. m.
.
from 6
Vi.
Sec.138. Restoration during disconnection period, evenif it is through
the meter, is
a criminalact entailing 3 years imprisonment orfine of Rs. 10,000 or both.
VII. Sec.145. Nocivil court has jurisdiction.
VIII. Sec.150. The utility officials can prosecute the ruffians and mislea
ding leaders for
abetmentof these offences even if it is against the provisions of Cr. P.C.
The black
sheepin theutility employees can be prosecuted as abettors wheneverthe
y even
just acquiesce.
Sec.151. The complaint can be lodged, inter alia, only by the emplo
yees of the
utility.
.
Sec.152. Compounding ofthe case is permitted at the specified rates.
S.No.
Nature of service
1.
2.
Industrial
Commercial
3.
Agricultural
4.
Others.
Rate per kw /hp /kva
Rs. 20, 000
Rs. 10, 000
Rs. 2, 000
Rs. 4, 000
appropriate government may change these rates.
acceptance of the compounding fees-by an officer empowered shall
amount to |
clean acquittal.
This can be availed only once for any person or consumer.
The
- The
Xl.
Sec.153. A special court shall be constituted for these cases with a
judge of the
cadre of Additional District andSessions Judge.
XII. Sec.154. Only Special Court. Summary trial with punishment up to
5 years. Can
pardon. Civil liability not less than 2 times the assessmentfor 12 months
.
XIN. Sec.156. Appeal to High Court.
XIV. Sec.157, Review by special court.
XV.
Sec.168. Protection for bonafide actions of assessing officer, public servant
etc.
XVI. Sec. 169. Assessing officers along with others are public servants.
XVII .Sec.170. Considered as land revenue.
XVII |. Sec.171. Notice can be served.on the person available, or
prominent place.
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Defective metering, billing and collection functions.
These losses are not due to any deliberate actions of the customers.
They are dueto internal shortcomings and henceare that much easierto tackle.
They thrive due to the fact that the boards did not function on commercial lines though
they were supposed to do so.
Metering:
There are many services unmetered. A large scale drive is necessary to bring all
unauthorized consumers on to the rolls. Such drive in Andhra Pradesh during a single
month of June 2000 resulted in metering of 20 lakh new consumers and regularization
of 2.57 lakh agricultural services.
The Act contemplates metering of all the services within 2 years and visualizes action
on the company and the individual officers responsible for lapses. So unequivocal
instructions are to be issued to not to release any new service without meter. All the
existing unmetered services shall be stopped to be so immediately. The utility should
concentrate on purchasing of adequate quantity of meters both for fresh services and
for replacement of the defective meters in the existing services. Purchasing of other
materials shall be given low priority, if the financial position demandsit. Other materials
can be purchased by the consumers.
Unmistakable instructions are to be given on the standards to be adoptedat the time of
releasing of new services. The service wire is to be brought in a pipe which shall be
‘visible throughout and end in the meter box with a gland. The meter, preferably
electronic, shall be fixed in a box visible and accessible from outside. The meter shall
be fixed in a box at a height of 5’to 6’ from the ground. Theparticulars of seal bits used
are to be noted and attested by the consumer. Proper earthing is needed ai the
installation. This earth, body earth and neutral are to be clubbed up on the meter board.
If ail these- precautions are taken, possibility for theft and defective metering are
reduceddrastically.
An exhaustive note on releasing of high value services is given separately.
The meters tend to get sluggish over a period of time. Old meters are to be replaced in
a phased manner by high accuracy meters, specially for high value |services and at.
places wherethe load varies substantially.
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C.T. meters are to be adopted in stead of whole
current meters for L.T. high value
services.
A comprehensive energy audit will pinpoint the area
s of high commercial losses.
Important services, feeders and towns are to be
taken up early for this exercise.
Actually, the biggest ever theft case was detected while
on one such exercise.
Following are the general defects observed in metering.
e
Many stuck up meters are allowed for years.
times, continuously.
:
¢ Constant nil consumption cases are reported witho
ut any comment.
e There are progressive readings in disconnected
services.
e There is considerable voltage drop in metering
cables.
¢ The meter capacity and the load have norelation.
e Wrong multiplication factors are adopted. After
the M. F.is changed, it is not
intimated to
the billing agency.
7
BILLING
Correctbilling and timely serving will go a tong awayi
n improving the collections. The
normal complaints in the billing process are: non recei
pt/ late receipt ofbills, receiving of
wrong bills, wrong reading/ status, table readings and
wrong calculations. All these can
be avoided in a single go by going for computerized
spot billing as is already done in
some
states. This can be introduced in stages start
ing from cities
. A thorough
understanding by the readers on the various statuses
of the meter is a sine qua non for
the successof the system.
Commonbilling software adoption is to be achieved
so as to have'a meaningful control, °
review, storage and retrieval of the consumer data
base. Even the application of CAT
would be moreeffective this way.
Monthly billing is to be achieved for the convenie
nce of the consumer and also for
. psychological reasons. Stringent checks are to be
adoptedin the billing process SO as
to plug the leaks.
.
SO
,
Thefirst bill is not issued oris issued late in many cases
. The customer service number
is to be noted on the meter at the time ofissue in the
sectionoffice.
The utilities adopt the last 3 months average in case
of abnormal meter status. A meter
becomesinitially sluggish and then Slowly drifts to stuck
up position. So the last three
months average would not give a correct picture of
the consumption. A study in A. P.
revealed that the utilities are annually losing scores
of crores onthis count alone.
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Very high consumption when compared to the similar connected loads indicates
unauthorized
additional
loads.
The services,
where the standard
deviation in
consumpiionis less than 2%, are to be targeted. Similar action whenthere is abnormal
variation. Constantly getting less than minimum in good areas should attract our
intention.
The powerdistribution companies have a unique advantage of contacting millions of
citizens at least once in a month. Thisis to be utilized fully to explain the latestinitiatives
and seek their support in their own interest and in the interest of the company. The
Tirupathy based company spared somespacein the reverse ofthe bill to an advertiser
and thusthebill making cost is saved.
Collection
Unbundling and corporatisaion will give a real boost for the collection effort. Every
citizen would feelit to be her normal duty to pay for the commodity she purchased. The
poor now have a tendencyto feel that they have a natural right to enjoy the government
bonanza. But even the poorest man will not dream of having a soap freely from the
seller. After reforms, therewas phenomenal increase both in demand and in collection
percentage in A.P.
Increased customer convenience shall be the guiding factor for smooth collections.
Drop box facilities and roping in more collection agencies make the lengthy queues
vanish. E seva centers are a relief to the customer as around 25 types of bills are
accepted in a cool atmosphere at convenient hours in the holidays too: Online facilities
like icici bill-junction are extended.
Special collection drives, coupled with intensive inspections, in the areas where the
paymenthistory was bad, broughtterrific results. Effective disconnection of defaulters
shall be a norm rather than a chance occurrence. CATis.to be applied and high arrears
services are to be targeted. Class F services, where the consumeris availing supply
without any payment from last one year are to beinitially tackled for more impact.
Reversal tll in the case of non paying consumers demand immediateattention. The worst villages: are to be adopted by DPE and vigilance wings and make them as
‘modelvillages. This will be a spark for others to act..
Every house shall have the service connection no. painted at the pole, gate and meter.
in fuse off call offices, before attending a fuse off call, they verify the defaulters’ list.
Only whenthese two conditions arefulfilled, the complaint would be attended.
The electricity revenue officials are to work and they are to be pin pointed for poor
collections. The revenue recovery act is to be made use of. There shall be compulsory
and immediate prosecution in the case of bounced cheques.It is interesting to note that
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no witness, except the bounced cheque, is nece
ssary for imprisoning the offender
promptly, in these cases.
The problem of fraud ever lingers on in the colle
ction process. In one case, a single
employee in electricity revenue office could knoc
k off more than one crore rupees in
about a year. Computerized monitoring system will
help here.
Increased booking of cases on thieves and defaulters
will bring real changein collection
scenario. Anti powertheft police stations (APTS)to
deal exclusively with these cases
are desirable to have any meaningfuleffect.
The role of users’ associations, panchayats
and franchisees in billing and
collection.
The electricity act 2003 visualizes the role of
Users’ Associations, cooperatives,
panchayats and franchisees in electricity distributi
on management especially in rural
areas.
The concept of paymentfor the power consumed
can be successfully inculcated if more
people are involved in the process andif a sense
of belonging to and stakein the entity
is created.
This is actually a continuation of the earlier
concept, which was successfully .
implemented in some countries in the sectors
of electricity, financing, sugar and
irrigation. Here much depends on the leadership, whic
h takes up the issue. In A.P. only
half of the cooperative electric societies are somehowp
ulling on and the other half are
recently merged with the concerned distributi
on companies. Loksatta, a voluntary
organization, is trying to take up certain areas now.
One major workers’ union, which
wasall the while supporting the reforms vehement
ly, is planning of plunging into this
workin a big way. ZLRI is taking up this workin Oriss
a...
A sincere effort should be made to induct mass lead
ersofintegrity into this movement.
Otherwise,large rural stretches in India have no
hope of enjoying quality supply and
required system growthfor the onsetoffull scale integ
rated developmentofIndia.
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BEST PRACTICESIN DISTRIBUTION LOSS REDUCTION
Single Phase HT Distribution System
by M. V. S. Birinchi, CORE International, Inc.
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Single Phase HTDistribution System
M. V. S. Birinchi, CORE International, Inc.
1. Introduction:
The loadsin rural area are predominantly pumpsets used forlife irrigation. The loads
have low power factor and low load factor. Further load density is low due to
dispersal of loads. The existing distribution system consists of three phase 11KV
lines of considerable size and 3 phase 11KV/433 volts distribution transformers with
lengthy LT lines. The system is based on British practice and is found to be
unsuitable to cater Indian Loadconditions, as the line losses are high, voltage profile
andreliability are unsatisfactory.
To improve quality of supply, one of the recommendations is the implementation of
single phase H.T. distribution system with small capacity and single-phase
distribution transformers. Under this system HT line i.e., 11KV line is extended as
near the load as possible and small capacity distribution transformers say 5, 10 and
15 KVA are erected and supply is released to the consumer through a short length
of LT lines preferably insulated over head cable popularly knownas aerial bunched
cable.
The idea is to have ‘Less LT System’ and gradually move on to “LT less system’.
Even the short LT iines are laid using Aereal Bunched Cables.
Advantages of H.T. Distribution System:
The advantages of H.T. distribution compared to conventional L.T distribution
system are indicated below.
i.
For the distribution of same power, the comparison of current losses and
voltage drop for (with 100 as base) L.T. are given below:
Single phase
6.35 KV H.T
distribution
3 phase 4 wire
475VLT
distribution
—
system
Current Amps
Losses K.W
Voltage drop
—
system |
11.0
8.5
100.00
100.00
12.7
100.00
The consequential benefits are
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a. Small size A.C.S.R or aluminum alloy
conductoror high conductivity steel
wire can be used.
b. Better Voltage profile
c. Reducedline losses
ii.
Both reliability and security of supply are impr
oved for the following reasons:
a. The faults on HTlines are far less comp
ared to that of LT line
b. The faults on LT lines are eliminat
ed as LT lines are with ABC. This in
turn
reducedthefailure of distribution tran
sformers.
c. In the event offailure of distribution
transformers it will effect only small
number of consumer
s. 2 to 3 Power consumers 10
to 15 domestic
consumers, whereasfailure of an existing
large size distribution transformer
will effect a group of 40 to 50 power
consumers 100 to 200 domestic
consumers.
3. Designof H.T. Distribution System:
The salient design features of the system are
indicated below:
i.
i.
The Scheme envisages running % wire 11KVl
ine (i.e. 3 phase and one neutral) from a
‘33/11 KV sub-station .preferably to adjoinin
g 33/11 KV sub-stations. 11KV singlephase 2 wire branches (phase and neutral)
are extended and one number 6350 V /
230-0-230 volts distribution transformer is erec
ted to feed single-phase loads. Since
single-phase motor capacity is limited to 15
HP, motive power loads of above 15 HP
are given by extending main'line through phas
e-convertersin isolated cases.
Three ratings of single-phase transformers
namely 5, 10 and 15 KVA are suggested.
The table below give the losses and costs of
single-phase transformers:
[Single
phase
transformer
5 KVA
10 KVA
15 KVA
No load
Full load
-loss
Cost of each
loss
40 W
40W
60 W
150 W
225 W
275W
transformer
Cast .
Oilfilled.
resin
5,800
4,540
6,700
5,260
7,960.
5,980
_|
In the distribution
transformers the coreloss is a continuous loss
whereas load occur
only when motor works (about 700 to 800
hours in a year). Hence core losses
constitu
tes substantial portion oftotal losses.It woul
d be very advantageous if the
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transformer can beisolated from the system, when the moioris not in use to reduce
core losses. In the absence of such an arrangement, as both 5 KVA and 10 KVA
single phases transformers have the same corelossi.e. 4 watts, and cost difference
is not considerable, it would be advantageousto install larger number of 10 KVA
transformers. Each transfer can eater 3 to 4 pumpsets, one atthe transformer
location and the other two or three on either side at an average distance of 0.2 to
0.25 KM. The savings in core losses are more than the lossesin the LT line and the
arrangementis also cost effective is the line cost is lower than the additional
transformercost.
iii.
The LT lines will be laid with aerial bunched cables (ABC) of size 16 sq. mm
with a bearer wire size of 25 sq. mm. The length of LT lines has to be kept
minimum to reduce LT losses. With the HT distribution system, the current
carried by LTlines is reduced due to usage of small capacity of transformers. It
is seen than the cost of line is cheaper, that the conventional LT 3 @ / 4 wire
line used in LT distribution system. The comparable cost of the ABC, ACSR,
current carrying capacities and the cost per KM ofline are given in the table.
SI.
Particulars
No
1.
Current carrying
2.
capacity in Amps.
Costofconductor
cable per KM in
Rs.
3..
7/2.11
1X164+1X25
2X1641X25
ACSR
sq. mm
ABC
sq. mm
ABC
115
74
88.68
1590 per
4515
7555
KM
3180 per
2
per
per
14,200
17,600
Cost of line per
conductors
4770 per 3
conductors
Single
K.M
phase
;
2 wire
14,500
SO3W.
18000
The major advantages of ABC is that the faults on-the LT lines are totallyeliminatedimproving the equality of supply. The ABC can be run on the building facades the
problem ofvertical and horizontal clearance does not arise.
4. Single Phase Motors:
The successful implementation of HT single-phase distribution system with its many
advantagesofreliability, satisfactory voltage conditions and not existent opportunity for
pilferage solely depends upon availability of good quality single-phase motors, because
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most of the rural loads are pumping load.
The single-phase motor chosenfor the duty
shall have comparable efficiency and price
with that of 3 phase motors now available
in
the market.
There are four types of single-phase motors
I.
Split Phase Motors: Split phase motor are
single-phase induction motors and
usually have a squirrel-cage motor. The
‘stator consists of iwo windings,
namely, a main and auxiliary windings and
are displaced in space from one
another by 90 electrical degrees. The diff
erence in the winding impedancesis
responsible for phase displacement betwee
n the field established by the two
windings. Thus a rotating magnetic field is
produced in the air gap andtorqueis
produced by the action of field on the squi
rrel cage rotor. A starting switch,
whichis usually centrifugally operated, disc
onnects the auxiliary winding after
the motor has attained approximately 70 to
80 percentof synchronous speed.
Capacitor — Start Motors: The capacito
r start motor, is similar to the split
phase motorin design except that a capa
citor s placed in series with auxiliary
winding to provide
the desired 90° phase displacement between
the main and
auxiliary fields. The auxiliary winding andits
capacitor are switched out of the
circuit by a starting switch, which is usually
centrifugally operated as the motor
nears synchronous speed.
Hl.
Two Valve Capacitor Motor: This moto
r has two capa
citors in auxiliary
winding. It starts as a Capacitors start
motor with start Capacitor in series with
the auxiliary winding. As the motor
nears Synchronous speed, the starting
capacitor
is switched out but running capacitoris
brought into the circuit in
series with the auxiliary winding. The auxi
liary winding and capacitors are
continued in running condition and ‘this
makes the motor operate more
efficiently, with an improved. power factor
and Slightly increased break-down
torque.
ee
Permanent —Split Capacitor Motor: A capa
citoris permanently is series with
the auxiliary winding and the auxiliary and
the auxiliary circuit remains excited
both under starting and running conditio
ns. Motor of this type designed for
continuous duty have low Starting torque (abo
ut 50 to 60 percentof the full load
torque) but this is adequate for the duty for
pumpsets. These motors have very
high PF. Generally more than 0.9. After exam
ining the characteristics of four
types of single phasemotorsit can be conclude
d that permanentsplit capacitor
motors are best suited for pumping loads
as these motors have high power
factor and the centrifugal switch whichis likel
y to cause maintenance problem
Is avoided,
“Motors:
Comparison with the Three Phase
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Today in the country good quality single phase motors of 3 HP and 5 HP ratings are
not available in the market. APSEB has taken up the issue of manufacturing proto
type single-phase monoblock motor pumpsets with three leading manufacturers
namely M/s General Electric Company, M/s. Crompton Greaves and M/s. Kirloskar
Brothers, who have evincedinterest in the project. M/s. Kirloskar Brothers and M/s.
Crompton Greaves have developed 2 HP and 3 HP single-phase motor pumpsets
and M/s. G.E.C. 3 HP and 5 HP single-phase pumpsets. Field tests are conducted
on these motors to evaluate their performance. The test results are indicated in
Table-l.
Regarding efficiency it is appropriate to look for “effective efficiency” figure, which is
defined as the product of efficiency and powerfactor. The low power factor motor
takes more current and in turn causes higher distribution losses. The effective
efficiency of 3 phase and single phase motors are indicated below:
P.F. Efficiency
Three phase motor
0.85 X 0.8 = 0.68
=
0.90 X 0.75 = 0.68
From the above it can be seen that effective efficiency of single phase motors*
comparable to that of 3 phase motors.
For comparison of costs it is appropriate the total cost of electrical installation is
compared. In case of three phase motors an external capacitor is required to
improve the powerfactor, whereasthis is not needed in case of single-phase motors
becauseofits inherent high power factor due to built in capacitor. The single-phase
motors also do not.require the conventional starter as there is no single phasing of
supply and a simple.M.C.B is adequate for protection of single-phase motor. Thé
comparable costs are indicated below:
Single
3Phase3
Phase 3
HP
| Single5HP |
3 Phase5
HP
HP
Motor with pumpset}
3700
|
3400
5400
500
---
4900
(Monoblock) |
Starter
---
MCB
.
Capacitor
GESRE
250
——
---
100
3950
4000
a
|
'
250
-—-
See
100
5650
5550
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From the aboveit can be seen that diff
erence in costs of single phase and 3 pha
se
motors is not appreciable. With more dem
and and further development, the prin
ces
of single phase motor Pumpsets could
further come down making it cheaper than
existing 3 phase motors.
5. Demonstration Project
Erstwhile APSEB has placed an order 18,4
00 Nos. Single Phase transformers (13,
800
Nos., 10 KVA., 1600 Nos., 4600., 15 KVA
). To popularize single-phase motors APS
EB
is placing an order for 150 Nos. Single pha
se motors (75 Nos. 3 HP, 75 Nos.5 HP)
and
setup a demonstration project around Hyd
erabad to conduct extensive field studies.
This project is expected to be ready in next
few months.
6. Case Study:
A single phase HT distribution scheme
covering 27 Nos. of- agricultural pumpse
ts is
formulated and capital costs and running
costs of the scheme are compared with
that
working schedule for capital costs and runn
ing costs.
The analysis of results indicate that:
i.
-The single phase HT distribution sys
tem is 25 percent costlier than LT
distribution system
li.
The power loss in single phase HT
distribution is only 7.0 percent of LT
distribution system
iii.
Benefits due to HT distribution system on
account
7. Conclusions:
Capacity. If the overall cost of the sys
tem is taken into account, the HT dist
ribution
system may be economical compared to
LT Distribution system. With regard to sing
le
phase motors required for success of
HT distribution system, it is demonstra
ted
that the
manufacturers in the country have
‘the technical know how and capabili
ty to
manufacture good quality single phase
motors which are comparable inefficiency
and
price with that of 3 phase motors. It can
be safely concluded that new generation
of
phase HT distribution system has to be
speeded up to give better quality of supp
ly to
our farmers.
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TRAINING PROGRAM
BEST PRACTICES IN DISTRIBUTION LOSS REDUCTION
Emerging Technologiesfor Distribution Loss Reduction
by M.V. S. Birinchi, CORE International, inc.
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EMERGING TECHNOLOGIES FOR DISTRIBUTION LOSS REDUCTION
(HVDS, ABC, METERING (ELECTRONIC, PRE-PAID, SCADA & D.A)
M. V. S. Birinchi, COREInternational, Inc.
Powerutilities in-charge of Distribution have taken numerousinitiatives to reduce losses
in the system which are discussedin this session.
HVDS
The loads in Rural distributions are widely dispersed and to fetch a small load of 4 KW
(5 HP) LT lines are run for long distances. For a 400 KVAload, the amperage at 11 KV
is 5 Amperes, where asat LT it is 140 Amps. Prior to introduction of HVDS, 11 KV, 3-
phase lines are run upto large sized 3-phase transformers 11KV / 433V from which
lengthy 3-phase LT lines are run. Such a system is found not suitable for Indian.
conditions, especially Rural, as voltage profiles is poor, losses are high and outagesin
supply are also high.
HVDS envisages running 11 KV lines right up to a cluster 2 or 3 pumpsets, employ
small sized distribution transformers (15 KVA) and extend supply to these 2 or 3
pumpsets with least (or almostnil) LT lines.
Single Phase HVDS
HVDS wasfirst attempted as single phase system (i.e.) running one phase of 11 KV
and oneneutral wire from 33/11 KV SS,install small sized 5, 10 or 15 KVA single phase
transformers 6350 / 230-0-230volts and changing all three phase .pumpsets to single
phase pumpsets.
ABC
. WhereLTlines could not be totally avoided, ABC (Aerial Bunched Cables) with a bearer
wire was used. The major advantages of ABC are that the faults on LT lines are totaily
eliminated, thus improving reliability and also theft by direct tapping is avoided. The
authorised consumer / consumers (a couple of them) do not allow unauthorised tapping
by another as their transformer gets overloaded or may get damaged, resulting in
outage of supply for longer durations.
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It was found that the single phase HVDS is not pract
icable as millions of pumpsets are
to be changed and also pump / motor mechanic
s at Rural level are not equipped with
- know howto repair or maintain single phase pump
sets.
Three phase HVDS
Existing LT lines are upgraded to 11 KV and
small capacity 3-phase Distribution
Transformers (15 KVA) are employed. The chang
eof insulators (pins, discs, etc.) was
enough.
Theworkinvolvesthefollowing:
Case Studies
Details of four cases where L.V.D.S. is chan
ged to 11KV HVDS and the results
obtained are explained below.
Studies are conducted by erecting a 11KV CT PT
set and HT trivector meter at DTR
location (100KVA) existing prior to conversi
on. The four locations are Kottur,
Murakkambottu, Patnam and Bangarupalem in chitt
oor district of Andhra Pradesh.
Existing LT Distribution of KOTTUR - SS - |
39 Agl Services
37} 8)
3.6 km LT Line
HT UNE
loo tua OTR
LY Btn
AC RAGULTUR AL Seawiers
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Existing LT Distribution of Murakambattu - SS Il
24 Agi Services
3.0 km LT Line
ost
¢
OFee
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trans
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toy kek OTR
ABUCUETORAL SERVERS
apiesel
ExistingLT Distribution of Patnam — SSIl
Oo TD
“one
9 Agl Services
1 no Poultry Service
rose
1oOMF
i
1.59kmLT Line
\ O 333
:
tene
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ast
Fane
r
“ETICVULTURA
LINES Lu
DE RVICES
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Existing LT Distribution of Bangaru Pale
m — SS IV
38 Ag! Services
3.3 km LT Line
Hy 21N&
(OO KVA
be
a
BTR,
LerNES
oe
SEevites
AGRICULTURAL SE
|
i
The details of cropping pattern, lengths of LT
lines, pumpsets with connected
load, percentage losses existing prior to conversi
on to HVDS wereasfollows:
Sugarcane,
paddy
Coconut,
mango | Sugarcane
garden, paddy and
part of the land
cultivated
2.
Length
3.
No
of LT
lines
of
3.6 Km
Pump | 39-
sets
4.
sugarcane
3.0 Km
Loads
Connected
179.5 HP
130 HP
5.
6.
No of days
Input
7.
Output
13 days
4290 units
14 days
3059 units
8.
| Loss of units
9.
% ofline loss
"
1.59 Km
.
3.3 Km
9
38
otal
;
40 days
3490.4 units | 2638 units
e,
Paddy, Coconut,
Mango Garden
by
24
ugar
90% paddy &
G.nut
130 HP
19 days
17672 units
6152 units
799.6 units
4271 units
14700 units
5149 units
18.63%
13.76%
16.82%
16.30%
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The HT layouts after conversion of the same areas are now asfollows:
HT and LT Layout of HVD System KOTURU — SSI-1
7
7
~Y
39 Agl Services
3.6 km LT Line
2.6 km converted to HT
1.0 km LT Line
11 Nos 15 kVA DTR’s
*
—_ BT LING
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AGRLULTURAL Seawites
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HT meresing
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H.T and L.T layout of HVD System Murakambattu SS I1
(24 Agl Services
‘5
3.0 km LT Line
2.04 km converted to HT .
0.96 km LT Line
10 Nos 15 kVA DTR’s
20% agpbe
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HT METERING
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H.T. and L.T Layout of HVD-System. Patnam SS-ll
{ 9 Agl Services
_
1.59 km LT Line
1.59 km converted to HT
8 Nos 15 kVA DTR’s
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H.T and L.T layout of HVD System Bangaru Palem SS IV
38 Ag] Services
3.3 km LT Line
2.5 km converted to HT
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9 Nos 15 kVA DTR’s
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The results obtained and a comparison between the parameters before and after
conversion to HVDSare plotted below:
1. | No1SKVA
8 nos
9 nos
11 nos
10 nos
distribution
transformer
erected
2._|
INPUT
1299 units
334 units
15 days
13 days
3.
4.
5.
OUTPUT
Loss of units
% of line losses
1229 units
69.7 units
5.30%
321.4 units
12.6 units
3.77%
5310 units
5019.2 units
5.47%
3926 units
3712.2 units
5.44%
6.
% ofline loss on
earlier LT
Distribution
System
% Net reduction
in line losses
16.82%
16.30%
18.63%
13.76%
(11.52%
12.53%
13.16%
8.32%
on HVDS
7.
The voltage improvement and loss reduction obtained in all the four cases are as
follows
Comparison between LT system with HVD system
KOTTURUSS -I
Length of HTlines
-
Length of LT lines
Noof Distribution transformers
3.6 Km
100 KVA—1 no/
1 Km
15 KVA-11 no/
Voltageat tail end
350 volts
% Line losses
18.63%
420 volts
547%
.
2.6 Km
MURAKAMBATTU SS-I1 100KVA
-| Length of HTlines
| Length of LT lines
No of Distribution transformers
Voltage attail end
% Line losses
3.6 Km
100 KVA—1 no/
385 volts
13.76%
2.04 Km
0.96 Km
15 KVA— 10 no/
430 volts
5.44%
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PATNAMSS-I 63 KVA
“Length of HT lines
-
Length of LT lines
| No of Distribution transformers
1.59 Kin
1.59 Km
63 KVA-I no/
15 KVA-—8no
Voltage at tail end
340 volts
% Line losses
420 volts
16.82%
5.30%
“Length of HTTines
-
Length of LT lines
Noof Distribution transformers
Voltage at tail end
- | % Line losses
| 2.5 Km
3.3 Km
100 KVA — 1 no/
320 volts
0.8 Km
15 KVA — 9 no/
430 voits
16.30%
3.77%
The Distribution losses which were as hi gh as 19% in some cases were brought
down
to 5.5%.
The results of improvementsin tail-end voltage, reduction of lossesareillustrated in the
table below for four case studies in Chittoordistrict of Andhra Pradesh.
Sl.
No.
Location
Tail End Voltage
(Volts)
1.
2.
3.
Kothuru
Murakambattu
Patnam
LVDS
350:
385
340
4.
Bangarupalem
320
Losses —
HVDS
420
430
420
LVDS
18.63.
13.76
16.82
HVDS
5.47 .
5.44
5.30
430
16.30
3.77
Advantages of HVDS"
e The. registered customer will feel ownership and take responsibility and not
allow others to meddle with the LT network.
e
Prevention of unauthorized loads by the consumers themselves since the
distribution transformer mayfail if loaded beyondits capacity.
¢ Failure will.be minimal because of on. over loading and-no meddling of LT
lines.
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e
In the event of equipment failure only 2 or 3 customers will get affected
instead of 25 to 30 customersin original system
e
High quality of supply since there is practically no voltage drop.
e
Less burnouts of motors because of good voltage and lessfluctuations
*
Considerable reduction in line losses and consequent savings in power
purchase cost
e
e
Since losses are reduced considerably, Power can be supplied to additional
loads without any further investment oninfrastructure.
No additional generation capacity needed for giving new loads due to
reduction in power drawals.
e
Accidents due to touching of snapped conductors reduced dueto the fact that
the breakertrips at substation since the line is at 11KV potential.
Metering
STATIC (ELECTRONIC) ENERGY METERS
Static Energy Meters re utilized now-a-days at HT Services and LT High value Industrial
services. The Static energy meters are microprocessors based. The programmability of .
microprocessor has become a useful tool to incorporate different features like Tamper
data, Import-Export, Time-of day metering, load pattern analysis, Remote meter reading
_etc. The availability of such meters made it possible for the ElectricityBoards to evolve
new meteringavailability of such meters madeit possible for the Electricity Boards to
evolve new metering concepts to cater to the requirementsofutilities and consumers.
The other important development is the advent of information technology, which now
provides solution to the development is the adventof information technology, which now
provides solution to the management and interpretation of large masses of data,
handheld devices. are used to gather information and. transport the sameto the larger
computersatthe utilities for Onward Processing.
The principles of measurements used in electromechanical systems and the equations
governing the measurements are still the basis for processor based meters. Only
difference is that, these equations are implemented with digital algorithms.
For example: single-phase active poweris given by:
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Kw = Vrms Irms Cos O
This can be written as
KW = 1/T ... Vi.dt
WhereV is the instantaneous magnitudeof
voltage
| is the. instantaneous magnitude of curr
ent and
T is the time period = 1/f
This integral measures the area under a
curve obtained by voltage and current wav
e
forms.
In discrete form, suitable for implementing
with a Processorbased mater, this equa
tion
can be written as
k=n
kw=1/N 2 Vk\k
where Vk and. Ik are the sample of volt
age and current taken simultaneously, n
is the
number of samples obtained in one period.
The poweris integrated over the time peri
od
to get the energy.
There are several techniques. associated
with Solid state metering the various
techniques differ mainly in the type
of multipliers used. These are briefly. desc
ribed
below.
4.
2.
3.
Mark space amplitude Multiplier
Hall Multiplier
Analog to Digital Conversion and sampling
Mark Space Amplitude (MSA) Multiplier
_In this type, multiplier voltage V is tran
sformedin to pulses whichis linear func
tion of
voltage (voltage to time conversions). The
se pulses are than amplitude modulated
by
current |. The integration of resulting sign
al is proportional to the energy when
time
energy reaches a predefinedlevel, the inte
grator delivers an output pulse which is then
processed, thefigureillustrates a simplifi
ed block diagram of a mark-space multipli
er.
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width
Modutetor
:
a
o
Sompting Switch. °.
‘
a ra
fu
ae
Samples are taken from the voltage to the pulse width modulator at a rage of some
definite frequency. As an output, a pulse frequencyis received, the mark-spaceratio of
which is varying according to the value of instantaneous input voltage. The voltage
output signal is used to drive a sampling switch. Height of the output pluses are
proportional to the instantaneous values of the current. At the output of the multiplier
there is thus a signal, the pulse with of which is proportion to the voltage and height to
current i.e., the average value of the ‘signal is proportional to the electric power. The
wave forms are shownin Figure 1.2.:M/s Schelumberger Industries Meter use MSA
Technique for measurement of energy.
Hall Multiplier
A poteniial difference is developed between opposite sides of current carrying conduct
_ subject to a transverse magnetic field. This is called Hall effect and the potential
.. difference, Hall voltage. The current carrying conductor is a semi conductor called Hall
Generator. Hall voltage proportional to
the product of the two input variables,
9 ©
oy
Axa".
current and flux.
The Hall effect is derived as a potential
difference Vh which will appear across
the width of a hall crystal when current,
1, flows along its length as shown in
Vb ott Output-
figure 1.3. and placed in a magnetic
field,
at
right
angles" to. these two.
——
direction, then Hall output is given by:
Vh = “10
Vh = Hall voltage in mv
K = Hall co-efficient of conductor is Cm*/couloumb
of
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[= Current in ma
B = Flux density in Kilo causs
t = Thicknessof plate in cm
M/s L&G Static meters use Hall effect principle
for measuring energy.
Analogto Digital Conversion and Sampling
e
Convertor:
Mulliplie®
Current to frequeney
convertor or w/f.-
-
The simplified block diagram is shownbelow
:
The input voltage and currents are isolated
from the line and sensed through.internal
potential and current transformers. The powe
r supply voltages required to operate the
electronics is derived from the input liné voltage.
The voltage and current are sampled
at suitable sample frequency and converte
d to digital form by. analog to digital
converters. Then these values are fed to the
microprocessor. The multiplication of both
voltage and current values is done by the micr
oprocessor and displays the energy. M/s.
Duke Arnics and M/s. P.l. Industries
(secure Meters) use this principle ~ of
measurements.
Static Meters
TamperData
The static meter can detect date pertaining
to tamper such as
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_
(a)
Missing potential: Gives the informant on regarding missing of supply to
the potential coil and records the date and time of such occurrence.
(b)
.T. polarity reversal: The meter can also give information regarding
_.- availability of load /current. The meter can also register the non-availability
of load in a particular phase comparedto the other phases.
(c)
Phase Sequence Reversal: The meter can also recognize proper phase
association.
Time-of-day Metering
The processor based electronic (static) meters have build-in Real-time clock. So the
time available in-a day i.e., 24 hours is devided into different time zones. The duration of
each time zone is programmable and the user can define their time zones as perhis
requirements. The meter records the energy consumed in different time zones in
separate registers and exhibits accordingly. This is known as Time-of-day metering.
This system is very useful forutilizing the available electrical energy in an optimum way.
‘-~ By revising different-tariffs for peak and off-peak energies, the consumption during
peak-loads can be discouraged. This helps in demand-side managementbyflattening
the peak of the demand curve.
Load Survey Data
The static meter has the provision to store thebilling and tamper data for 35 days at the
specified logging interval, say 15 Mts/30 Mts. This is useful to draw the load curvesof
KWH & KVAH, KVA & KVAH..This is known as load survey data which gives complete
’ picture of load pattern of that consumer.
The utility should give strong consideration to using meters with load survey data.
Especially for those meters on the DTs (either high side or low side).. The interval by
interval data from this function helps in several ways.
e The energy supplied to the feeder(s) by the DT can be windowed(sliced) so that
it aligns with the energy consumption from the route meter readers. This reduces
the “time parallax” problem that plagues energy accounting at the feederlevel.
* The magnitudeof the peakload onthe transformer can be measured. e Thetime of the peak load on the transformer can be measured.
If the meter is on a customer, especially a large customer (KWHor Rs) the load profile
can be analyzed and suspected times and methodsoftheft of service can beidentified.
Such “signature/ signal analysis” may not be proof of theft of service, but in the hands of
a revenue protection expert it can help them identify the methods and times of theft.
Investigation and prosecutionwill follow, if appropriate.
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Import/Export Metering
The static meter can measure
the energy in both direcition etc., the consumeracting as
a load for some time and feeding into the grid for some
other time. This is known as
Import/Export metering.
Meter Reading Instruments
The meter reading. instrument (MRI) is a simple hand held
terminal used for data
transfer from/to meter to/from the system-computer. MRI can
be usedfor data transfer
from HT trivector meter for analysis of data & billing. The
MRI can be preloaded with
meter numbersto be read and optionally the MRI can also have
a bar code reader. The
bar code reader will be useful to identify the serial number/ide
ntify of meter. In case of
H.T. services with load survey data, MRI is very essential for
transfer of data from meter
to computer as the data collected is enormousandis not possi
ble to read manually.
The MRI can also be used for LT energy meters. MRI can
also be made to have a
printer attachedto it and a bill can be generated immediately
upon reading the meter. In
this case
the MRIshall contain the meter serial numbers to be read and the
previous
reading. The entire data can be off-loaded at the endof the
day.
Telemetering
Transfer of metered data through a communication network
is known as telemetering.
The meter shall be connected to Say a telephone line
at the consumer end via a
.Modem. At the system end also the computer is connected
to the telephone via a
modem. Wheneverdata is to be accessed by the computer,
the consumer telephone
numberhost be : dialed, and the modem connected to the
telephone will connect to the
meter. This type of metering system can be very useful in case
of H.T. services as well
as substation/services.which require constant monitoring.
PREPAID METERS — A NEW CONCEPT
Introduction
-
Payment before use of electricity by the consumerwill elimi
nate difficulties involved in
reading of energy meters periodically, preparing bills and collec
tion of revenue. Under
this scheme, the consumer buys a Specific number of units
of energy as per his
requirement by paying the cost in advance. The electr
icity metering devices
(consumer's meter) have the facility to read and store the
number of energy units
bought by the consumer, to subtract the energy consumedb
ythe user and to cutoff the
main supply on exhausting the units.
.
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Prepaid meters have been in existence for over a few decadesin the form of coin-inthe-slot electricity meters. In these meters a coin (say one rupee) is to be inserted to
obtain oneunit of energy. Such meter present enormous administrative problems.
Consequently the methods of implementing the pre-payment schemes have undergone
a sea change. This becamepossible mainly because of the advances madein thefiled
of electronics. In this paper, the latest electronic methods used for prepaid metering are
presented anda schemefor implementingit in the Indian conditions is proposed.
in India the mobile phone system has pioneered pre — payment systems, and so the
electric utilities can be offering a payment method that has already found acceptance by
the public and the regulators.
Prepaid Meter is an Elementin a Revenue Collection System — a Schematic View
Fig. 1 illustrates the use of prepaid meters as an element in a revenue collection
system. It may be seen from this schematic that the previous (pay after use scheme)
activities of periodic meter reading, preparation on bills, collection of revenue,
monitoring of revenue and issuing disconnection notices are all replaced by just two
activities, namely:
1.
2.
Vending of pre-payment device.
Monitoring for fraud.
For both the aboveactivities a single computeris sufficient as describedlater.
3:
Facilities Required in a Prepaid Meter.
Fig. 2 illustrates the Facilities required in a prepaid meter. While someofthe facilities
are essential, some of them are optional. The consumer buys his pre-payment device
(detailed more in the later sections) from any of the EROs which are distributed
geographically.
“BONS
The pre-payment device contains details on :
" Consumernumberagainst which .the: pre-payment was made.
Numberofunits for which the pre-payment was made.
Presentrate of tariff.
Maximumcredit allowedin liew of the deposits already made withtheutility.
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'. Moin frome computers
wit Debts
stormer: Trapord vending
zy
So ge Oe
fl
+
“Customer prepaid meter
Figure-1 : Prepaid Revenue System
”
Reverse
Rote'of
power ied
Meer
consuption fed
.
"|. Register.-
Audible buzzerpe
{Th Totctiser_.
:
-
Real-time
-Lo— |
—shhased
—J f
Lood/Toritf [o.<"") Credit/Debt
conirof
*
. management
Auxitiory
reloy” or
: “s
; on pho
system [|
“hs
—
se he ae Be
_
ee eee Posh,but ton
~~“Tfor disploy
:
eoa? Write
Figure 2. Meters Block Diagram
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The information onthis device, when inserted into meter, will be transferred into the
meter and the meter automatically cancels the pre-payment advice, sc that the device
may not be used again without further payments.
The meter now updates the credit available by adding the balance of the previous prepayment advice with the current payment advice and reads backwards showing the
balance amountof energy due to the consumer. When the balanced is reduced to a
minimum level, an audible buzzeris actuated for about % a minute. When the consumer
ignores this warning and continues to use the electricity , when the balance reaches
zero the poweris automatically cut — off.
In a more sophisticated system a credit may be allowed which will be subtracted when
the next payment advice is received by the meter. Also when different types of tariff
(like TOD), the Real Time clock calendar takes care of the different energy rates for
different timings.
Pre-Payment Methods
The old methods of pre-payment iss by!‘coins-in-the —slot” where the consumer puts in
cash or tokens boughtfrom theutility company.
In either of the above cases, collection of revenue is conducted at the consumers
premises. Administratively, it is very difficult to transfer the cash or tokens from the
consumerlocation to the utility office. This method is highly susceptible to frauds and
thefts. Also the locks on the coin meter can never be madeso strong as to withstand
the outside break-ins.
Fortunately, the developmentof electronics and its application to credit card markets
have thrown in many choices to improve the pre-payment methods. Of the many
. methods available, the following two methods are becoming more and more popular..
1.
2.
Key type vending
° Card type vending
The Customer Key is designed to be inserted into the meter’s key receptacle which is
’ fully isolated from the meter’s electronic circuit. The key comprises an over-molded
P.C.B. Supporting a 1K bit EEPROM. The key contacts are of nickel plated copper with
a gold overlay giving a life expectancy in excess of 10,000 read/write operations. A
space is provided on the key forindividualidentification markings.
The customerkeyis primarily for use as a high security meansof transferring credit to
the customer meter.
The individual customer key is personalized to that customers
particular meter and cannot be used with any other meter.
mm
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As well as being able to read and transfer meter readings from the
meter back to the
point-of-sale equipment, the key can be programmed with all the neces
sary parameters.
These can be transferred to the meter along with the credit inform
ation. Without ay
changes to the key or the meter, the future expansion of the key
system to cater for
automatic key parameter updates direct from the mainframe computer
via the point —of
~sale equipmentcan easily be achieved. Key vending and programmingf
acilities need
to be fully supported by a comprehensive maintenance and after sales
services.
The second system consists of customers magnetic cards availa
ble, in fixed
denominations, say Rs.50,100,500. It is like a credit card and
carries a magnetic code.
This is simply inserted into the card slot of the meter. If the card
is valid, its value is
credited to the meter, its code automatically erased and visually and
actually marked to
prevent further use. The meter also hasa facility to count the numbe
rof cards inserted
and registers the total value inserted in the meter. The card can be
bought from any of
the registered vendors, who charge a nominal fee for the service.
The choice of any one of the above systems, dependsonthefollowing.
A.
B.
C.
Integrity of the vendors
Security level for communication with meters and
Level of monitoring for fraud.
Distribution Automation
Power distribution systems havegrownin size and complexity in
the last decade. For
example, the consumer base in Andhra Pradesh has reach
ed 13.6 million, which is
twice the figure in 1990s. With increase in volume of workload, the
technologies also
should change. Continuance with conventional manual systems
is going to prove a
luxury in terms of cost apart from resulting in consumerdissatisfactio
n at the quality of
service rendered.
The Athens Utility Board in North Carolina, U.S.A, which is perhapsthef
irst utility in the
world to achieve 100% distribution automation by 1990, has observ
edin its report “It is
.. amazinghow.well this country has proposed on rule of thumb, flip a coin and
gut feeling .
decision making during 20" century. We will not be allowed this
luxury in the 21°
century”.
oO,
,
.
The utility has installed SMART meters at consumers premises
with miniature circuit
breakers that can be addressed and controlled from the utility.
For example, when
the
system is in distress, it can disable certain appliances like air condit
ioners, washing
machines, mixies, geysers, etc. from being used and enable lightin
g and fan loads.
Reading of meters, change over of feeds (reconfiguration),
adjustment of transformer
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taps for better voltages, switch-on capacitors, controlling distribution transformers and
online energy audit, etc are all achieved remotely.
This is apttime tostart ‘Distribution Automation” starting with Metros and rolling it out
gradually to towns and villages. A clear road map towards achieving Distribution
Automation is to be laid down with no further delay and start implementation forthwith.
The automation system can be designed using available technology in computer
systems, control systems and metering systems and dovetailing the same into the
existing power systems. All the tools required such as Computers, Remote Terminal
Units
(RTUs),
breakers,
Switched
Capacitor Banks,
OLTC Transformers, Auto
Reclosures, Sectionlisers, AMR Systems and Communication Systemsare available.
Anintegrated Distribution Automation system enablesutilities to have real time control
over the costly energy sold. Improved efficiency results in lower costs, better reliability in
power supply, planned control actions, optimum powerfactor, reduction in losses.It
enables online energy audit (AMR Systems), which is now receiving the focused
attention ofall utilities.
An integrated distribution control system mainly comprises of systems necessary for
Data Acquisition, Voltage & reactive power controls, System reconfiguration & Load
Control. The components used for these are primarily Distribution remote terminalunits,
Pole top units and Distribution control receivers.
APTRANSCO Experimental Projects
in 1992, a completely indigenous microprocessor based substation supervisory system
called INSYST 33 was commissioned at Indira Park, Greenlands and Kalyannagar
‘Substations and the RTUs were erected. The interfacing work with .CTs, PTs and
. auxiliary switches of circuit breakers, etc.was done by Master Plan Circle. The RTU.is
rigged up by a team of Engineers of BHEL (R&D) and Master Plan Circle, who worked
hand in hand to put the precept into practice. Remote acquisition of data and remote
control of the substations from Vidyut Soudha were achieved. It was then decided to
draw up a scheme for comprehensive Supervisory control and Data Acquisition ©
(SCADA) covering 120nos substations in and around Hyderabad andto control all of
- them from a Host Station. The scheme is implemented andis-in operation sirice one ©
year.
This scheme provides for real time monitoring of operating parameters of Amps, MW,
MVAR, PF, Frequency, Voltages, etc at all points of the substation, status of circuit
breakers, remote operation of circuit breakers and archiving of historical data, audio
alarm and annunciation for limit violations and breakertripping, recording of sequence
of events, recording f maxima and minima of operating parameters with time of
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occurrence, cumulative energy fed, etc.
This is now integrated with Computerised
:
Trouble Call
System, which receivesall fuse off calls in twin
cities.
This Distribution Automation System aimsat achi
eving
~
-
Control of DTRs, HT services and individual loa
ds apart from 11KV feeders.
Operation oflines sectionalisers, motorized isola
tors, auto Reclosures
Data acquisition from load end CTs and PTs
Operation of CBs for switched capacitors bank
s
Use of customized EMS software packageswit
h real time data collected through
RTUs
Issue, control and receiving back ofline clear
s, introduce interlock and safety
algorithm, password protected operating envi
ronment.
Real time logging of data / archived records of
hours of service.
Equipment data base
Integration with Automated Mapping(AM) and
Geographical Information System
(GIS) Software packages
Integration with Distribution system engineering
software for network planning »
The other functions achievable through Distributi
on Automation are:
Network
- ‘Distribution Transformer control
~ Monitoring and Control of LV breakers
- Trouble call management
ConsumerInterface
- Load monitoring and-control
- Voltage monitoring
- Metering and Billing through AMR
- Immediate detection of attempts for meter tamp
ering
- DSM objectives (individual pump control or
group of pumps or DTRs)
- Monitoring of captive generation when sync
hronized with system network
Miscella
neou
s func
tion
ce
s
na
ne
ou
s
-
-
Load forecasts and load surveys
System statistics
Optimalnetwork planning
Energy Audit
A Distribution Automation system basically
comprises of a distribution contro! center
(DCC), devices to be monitored / controlled
like Substations, Switching CapacitorsSpace for
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Banks, line equipment and a reliable communication system that forms the backbone
for successful operation.
Z
Distribution Control
Cenire (DCC)
The
iio
Distribution
Control Centre (as
shown on the right)
consists of Computer
system with software
for Data Acquisition
and
storage
Communication Interface
applications,
media for
storing
the
Data,
Visual Display Units
(VDUs) for displaying
the data to the
operators
and_
to’
issue
control
commands
communication
interfaces.
Modem
a
A
Vv
¥.
Data Acauisition
CH
Disc
Storage
and
Long Term
Data Storage
Tele Control Svstem
Computer Hardware and Software
Operation and Supervision
‘Mimic
Board
Alphanu
meric
VDU
System
Console
. Communication Options
The communication options for achieving DistributionAutomation are:
--. Radio (UHF).
-
DLCC uses the power lines for transmission of data (where commercially
available)
-
Optic Fibre (Cosily)
-
Public switched telephone network and paging services for auto dial--up schemes
(wherewide coverageis available)
One-way VHF radio can be used for load contro] because low cost load control switches
are available for this technology. VHF radio switches can also be used for capacitor
control on the distribution network, in lieu of more expensive RTUs with remote MARS
radios, if monitoring is not essential at the capacitor banks.
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Communication Selection for Hyderabad SCADA Project
The Radio Technology based communication. system is chosen for Hyderabad SCADA
project. In this a TDM / TDMA System operating in 2 Ghz bandis chosen as the primary
communication. The Central Station for this system is located at DCC, which
has 60
trunks of 64 Kbps capacity to provide high quality Data and Voice Communication.
Connectivity from DCC is provided by this system up to EHV substations which
are
nodal points of the Power System by installing TDMA outstations. Two TDMA
Repeaters are also provided to overcomeline of sight problems and to ensure better
coverage. At the 33/11. KV substations MAR remotes are installed. These are
connected to EHV substation by co-locating MARs MasterStations at nodal points and
by connecting them back to back to TDMA outstations. MAR remotes at 33/11K
V
substations or at any field locations will be polled by the MARs Master Station.
Thus
data acquisition / sending control commandsto the controlled equipment is ensured
in
this project.
Sub-Station Telemetry
Equi ment
Remote Terminal Units (RTU) are to be provided in each of the Substations for
acquisition of substation data parameters, transmitting them to the control centre. The
RTU’s will be rugged, intelligent and microprocessor based. All activities including /O
data processing and communication will be done using microprocessors. A typical RTU
is.a self-contained unit with CPU, RAM, EEPROM, RS 232 communication ports, power
supply, protective circuitry, analogue and digital 1//O channels with signal conditio
ning.
The I/O moduleswili be selectable to achieve the quantity and mix of I/O needs for each
substation. The RTU givespriority to telecommandsfrom the control centre overits data
acquisition tasks and at the same time ensures that the background scan of all the
events at the controlled substations are carried out and no event is lost. A typical
schematic RTUis given below.
a;
"L
:
Analog
WO)
RealTime
Clock
:
1 oN
|} Data |
{|
R ‘+
a
}
!
>
&
ee)
'
M
'
8
ror
&
[Pp nnn nw18
AID
1
Converter!
EEPROM
Memory
Tomer
}
|
1
Program
PROM
}.
i
1
Pea eee bhe-- wee 2
Digital
4
.
-
t
:
Central Processor
>|
Modem
——
Communication
equipment
:
™:
7
—
oc
=
:
L
Y
Interface
Module.
Circuit
Breaker
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The functional capabilities of the: DAS (Distribution Automation System) for distribution
operation are:
e Supervisory Control and Data Acquisition (SCADA)
e Historical Accounting and Reporting
e Load Control of HT consumers
e Automatic Meter Reading
e Feeder SCADA including fault localization, restorations of supply and load
balancing
e
Integrated volt/VARcontrol
e
e
Automatic Mapping and Facilities Management
Trouble Call Management System
Pole — Top
RTUs
Functions in the field are performed through Pole Top RTUs. They are similar in
functionality to the RTUs except that their 1/O handling capacity is small. These are
installed on Distribution poles to control the equipment online, such as.a line AB
switches, capacitor banks, voltage regulators, etc. To obtain information form pole-top
RTUs when needed, operators shall be able to manually request the polling of any
specific pole top RTU. It would be possible to issue polling requests for an RTU by
selecting a cursor target from any display, tabular schematic, on which that RTU is
displayed. Manual polling requests shall be processed on a higherpriority than any
». periodic scan activities. Scanning of pole-top RTUs shall be’distributed over time in
‘order to minimize the impact on the faster substation scan. Distribution Automation — Operational Methodology
Voltage Control
A pole top RTU with a MARSremoie is installed at each voltage regulator / capacitor
bank location and interfaced with it for getting input data of feeder voltage at the
monitored point, reactive loading, current tap position of voltage regulators, on/off status
of capacitor banks and to do switching operations of capacitors and voltage regulators.
The location and capacity of capacitors / voltage regulators shall be decided using an
optimal strategy. The switching schedule of capacitor banks is to be obtained for
minimal loss strategy while simultaneously satisfying the maximum /minimum voltage
constraints on the feeder. A similar method is required for determining the voltage
regulator taps also. Here, the regulator tap position is placed in maximum possible
position as long as the voltage at the maximum affected node does not exceéd
maximum permissible voltage limit. The on / off switching commands for capacitor
banks and raise / lower commands for voltage regulators shail be issued to pole top
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RTUs either through supervisory control automatically or through manua
l control by the
operator. A feedback of the change in status due to contro! comma
nds have to be
obtained and the results have to be displayed with any alarm / even
messages as
required.
Fault localization and Restoration
Wheneverthere is any fault on a feeder, the circuit breaker (CB) for that
breaker trips.
Test charging is done by closing the CB for twoto three times at an
interval of a few
minutes, to ascertain whetherthe fault is a transient one. The last test
charging is done
by opening the isolator and closing the breaker to ensure that the fault
is not in the
breaker. If it is ascertained that the fault is permanent andis on
the feeder, the circuit
Breaker is charged again and the switches are closed one after anothe
r starting from
the substation end. Whenthe breaker is in closed position andif it trips
before thefirst
switch Sectionlisers is closed, that fault is noted to be in between the substa
tion and the
first switch (i.e. in the first section). Every sectionlisers closes after
a definite time and
interval and the fault is noted to be in the section beyond the most
recently closed
sectionlisers switch. The fault section is isolated’ by opening switches
at both ends of
the section. Supply to the healthy between the substation and the faulty
section is
resorted.
.
Provision for sectionalisers to close can be by stand above automation
by a software
program for operation of switches by the operator through SCADA.
Trouble Cail Management System (TCMS
The outage of supply is reported by the consumers to a centralized
Fuse Off Call
Centre. TCMS helps to analyze the reasons for outage reported
by the consumer/
consumers and take remedial action to restore supply speedily using
this function. For
instance, when outage of supply is reported by a large number
of. consumers in one
area, it may be probable to trace the reason to blowing off of a sectio
nal fuse of
distribution transformer. By maintaining database of consumers
connected to each
transformer or feeder, such an analysis could be made easily. By
providing SCADA
connectivity to fuse off call centres, the operator at DCC will be
able to analyze the fault
and sendrectification gangs for speedy restoration. This function helps to
reduce losses
due ‘tolong interruptions and improve customerrelations.
Conclusions
e
Implementation of Distribution Automation cannot be delayed anymor
e. Infact
delayin automation mayproveto be a luxury.
e
Substation Automation, 11KV feeder controls, LV System control
s, AMR, DSM,
Online Energy Audit can be achieved.
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°
The cost towards Automation is generally recoverable in two to three years pay
backperiod.
e
Distribution networks provide an interface between the-consumersandtheutility
and any amount of sophistication on the upstream side with a less efficient
distribution system cannot provide satisfaction to the consumers.
Intelligent Distribution Transformers
Distribution Transformers (more popularly referred to as DTRs) from the essential link
between a. powerutility and millions of its LT Consumers. Phenomenal technology
advancements have taken place in Generation and Transmission sectors but the same
in Distribution are not equally spectacular. The engineers in-charge of Distribution deal
with lesser quantum of power and energy but have to provide satisfactory power supply
to a very large number of consumers. The technological solutions for adoption in
Distribution Sector shall be a compromise between ‘technically desirable’ and
‘economically viable’. The efficiency of monitoring the Distribution System essentially
lies in the effective performancemonitoring of a DTR.
DTRs are supposed to be least prone for failure as they are most rugged with all their
‘componentstightly clamped and norotating or moving partsinside. It is unfortunate that
in most of the Indian Powerutilities, the rate of incidenceof failure of DTRs is around 20
percent per year.
All the reasonsforfailure like loss of diversity, overloading, unbalance in loads, low oil
=. levels, loose spans, improper earthing, inadequate protection, etc., are being explained
away stating that they are unattended and unmanned. It is true that the DTRs are very
“large in number and are scattered over large areas but technology can always find a
solution for overcoming the problem. When the volume increases, technology shall
change and adherenceto old conventional manual systems can no longer be continued.
Attempts have been made on a pilot basis to implement Distribution Automation. The
first of one such attemptsis Gachibowli Distribution Automation Project in Hyderabad,
Andhra Pradesh
Gachibowli Distribution Automation Project
In the year 1995, the Department of Electronics (Govt. of India) has awarded a Pilot
‘Distribution Automation Project called Gachibowli Distribution Automation Project to be
implemented jointly by erstwhile APSEB and CMC the project was implemented
covering one 33/11KV Substation, 20 nos.,
Distribution Transformers,
50 nos.
Agricultural pumpsets, two High Tension services, two numbers Capacitors banks. and
10 nos., load break switches to be controlled from Gachibowli Substation. Pole top |
RTUs with two way Multiple Address Radios (MARS) Communication was used to
control DTRs, H.T. services, capacitor Banks and load break switches, VHT one way
er
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radios were used for the control of agricultural pumpsets (i.e.) to enable or disable a
consumer from running his pumpset.
Pole top RTU employed in Gachibowli DA Project
The pole top RTU (PRTU) developed in Gachibowli Projectis similar in functionality to a
normal Remote Terminal Unit (RTU) but has less input/ output handling capacity. The
lO handling capacities provided are’ Digital Inout module — 16 inputs, Digital Output
module — 16 inputs and Analog Input module — 16 inputs.
These PRTUis designed to be powered either by 110V or 230 V AC. The RTU has a
serial port to which a radio can be connected for data transmission to the control centre.
The PRTUis built to house a MARSradioin it throughwhich it communicates to DCC at
selectable baud rates.
lif Kanpur Experiment
Government of India (Ministry of Power) has identified IIT, Kanpur as lead agency for
developing technologies in the area .of Distribution Automation and a workshop cum
technology dedication event was held at Kanpur on 22™ & 23" February, 2003. A
practical demonstration of a pilot level project covering one 33KV SS with two power
transformers, two 33KV circuit breakers with their isolators, three DTRs with 11KV & LT
Load break switches (LBS)installed within IIT campus was made andthe indigenous
technology developed is dedicated to the nation by Secretary, MOP of Governmentof
India.
,
Remotely operable LBS (Load Break Switches) for 11KV operation and MCCBs
(Moulded Case Circuit Breakers) for 415 volts have been developed and field-tested in
the Distribution network inside the IIT Campus. The 11KV three pole LBs for outdoor
operation are rated for 80 Amps., with-an opening time of 100 milli seconds. They can
sustain a fauit current of 16 KA for one second and have a breaking capacity of 1.5
MVAto 0.7 pf and with a dynamic peak withstand capacity of 40 KA.
The LT LBSs are designed for a rated current of 200 Amps., with rated short circuit
withstand strength of 35 KA between phases and 21 KA between each phase and
neutrals for oné second. These are designed with ‘Solenoid Plunger’ arrangementas
operating mechanism.
.
.
A practical demonstration of remote monitoring and controlling of DTRs has been made
during the workshop-cum-technology dedication eventin February 2003 at IIT Kanpur.
APCPDCL Experiment
- Andhra Pradesh hasa flair to embrace and adopt new technologies and try them out on
pilot basis in practical networks. The Central PowerDistribution. Company of AP has
MATERPATIONAL I.
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adopted the technology and four distribution transformers located in different districts
are being monitored from centrally located DCC (Distribution Control Centre) at
Hyderabad using Cell Phone connectivity. This exercise is being done successfully from
January 2003 onthe following DTRs. |
District
33KV SS
Rangareddy Himayatsagar
-Rangareddy | Kesavaram
Medak
Narsapur
11KV
Feeders
Azeeznagar
DTR location
Anantharam
Kagaz
Mazdoor
Sts)
Jamathota
Umpathy
Gardens
Monitoring
being done
3 Phase current
and voltages, pf
load survey with
last35 days
data storage
- do Instant values of
3 phase
currents,
Nalgonda
Bhongir
Chandupatla
voltages, p.f, etc
- do -
SS -— 17
The successful experiment. clearly demonstrates that a Distribution Engineer can™
monitor on real time the operating parameters of every DTR andinfact he can chit chat ©
with his DTR as frequently as is necessary.
Electronic meters (CT operated) with RS232 port are erected at the DTRs and have
facility of storing data for the last 35 days for conducting load survey. Cellular
connectivity using GSM Modem is employed for data transmission to DCC using
Wireless Access Protocols.. Instantaneous readings of three phase currents, voltages,
phase angles, powerfactor, active power, status of CTs, etc., are obtained and printed ©
out at DCC for these DTRs. Also load survey with 24 hours data on any selected date
can be retrieved remotely from DCC.
The meter proper is capable of measuring electrical energy in all four quadrants, active
as well as reactive, max demand, etc., and hasall facilities for TOD, tamper proof data,
self diagnostics, and an optical port for communicating with CMRI orto an external
device like RTU for SCADA application. These meters are now to be equipped witha
remotely operable relay, which in turn closes or opens LBs andalso report back Status
using potential free auxiliary contact.
Communication Options
Unlike traditional communication options, the approach is to have a core communication
controller at the Base Station, which can support diverse choices of communication
media
(ie.)
Dial
up,
Ethernet,
WLL
(CDMA),
GSM,
etc,
for
cost
effective
implementation. Out of the options of PSTN, PLCC, Radio, etc., the employment of
GSM modemsis found to be best suitable in areas having cellular corridors.
wy
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. Distribution Reform, Upgrades and Management (DRUM)Tr n
aining Program
intelligent DTRs
It is desirable to have inbuilt intelligence into the
DTR, considering the following aspects
i.
Monitoring the various operating parameters
of the DTR such as load,
temperature rise and oil levels which are helpful
to detect the abnormalities and
provide opportunities to take corrective actions to
avoid failures.
ii.
Measurement of energy sent out to achieve effec
tive energy audit.
iii"
Housing the electronics and communication inter
faces capable of withstanding
the heat and oily environmentin a safe way withi
n the DTR to avoid meddling by
consumers.
lt will be advantageous if DTRs are manufactured
with built in facilities of CT operated
electronic meter which can store data for the last
30/60 days, remote reading facility,
anda remotely operable relay to perform control
operations. A float switch to monitoroil
level-in the DTR can also be incorporated. A comp
rehensive unit, which can be called
“Intelligent DTR” can be manufactured withtotall
y indigenous technology.
Initial estimates indicate that the cost of an Intel
ligent DTR may betwice the cost of a
conventional DTR of equal rated capacity but subst
antial reduction can be achieved if
these are procuredin very large quantities.
Powerutilities are spending large amounts
on repairs to DTRs and with the amount
spent on rectificat
ion of every three failed DTRs, a new DTR can
be procured. To start
with repairs of failed DTRs which are 20 year
s old, those which have already failed
twice, and those requiring replacementof all thre
e limbs can be dispensed with and new
DTRs can be procured with built in intelligence.
This may incidentally from step no.1
_. towardsDistribution Automation in Indian Powerut
ilities.
International experience shows that, the automati
on projects have high benefit cost
ratios and less payback times. Now there is no
option except to go in for Automation of
DTRs astheyare large in number and are continuous
lyincreasing to improve quality of
service.
Several leading Indian Transformer manufact
ures of CSP and amorphous core
transformers in the country have come forward
to manufacture “Intelligent DTRs”(i.e.)
DTRs with inbuilt facilities for remote monitoring
and control adopting totally indigenous
technology. The R&D activity has already start
ed and catching up momentum as they
have setup a short-term goal to achievethis.
Sixty-three districts in the country are chos
en for APDRP (Accelerated Power
Development Reform Programme)and the District
Head Quarters shall be thefirst to be
automated. The Distribution networks in these town
s shall be upgraded to 100 percent
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technical standards and made amenable for Automation. CSP transformers have
already got a breakerinside the transformer which open out for overloads or excessive
temperature and these can be attempted for conversion asIntelligent DTRs.
Fruits of Implementation
lf the above Schemeis implemented, the following benefits can be achieved whichwill
be the beginning of a new era ofefficient distribution systems in the country.
DTRscontinue to be unattended butwill be monitored remotely online.
Instantaneous voltages, currents, active power, reactive power, power factor
(perhaps temperature andoil level also) can be monitored remotely.
Unbalancesin voltages and currents can be detected and corrective action can be
initiated
Hours of powersupply through each DTR can be monitored and data stored to
compute thereliability
Energy Audit will be possible at grass root level
.
wee
Substantial reduction in failure rate of DTRs as impending failures can be
detected in advance
Quality of power supply will be ofthe highest order
Load survey makes Distribution Network planning and meaningful
Phenomenal reduction in losses can be. achieved through reconfiguration |
. roistering, etc., whichis possible to do remotely.
Total consumersatisfaction
Information TechnologyInitiatives in Electricity
Distribution Systems
(Those implemented in APare explained)
1. The IT initiatives in powerdistribution systems are aimedat
Improvementof efficiency by way ofelimination of delays, duplication, drudgery
in paper work
Reductionin over all expenditure
So
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Provides quick and efficient informati on syst
emslike online Billing & Collections,
online report generation
Customer satisfaction
Very fast reconciliation between impo
rtant activities of Metering, Billing &
Collections
Webbasedservices for 24 hours X 365 days
To attain transparency and gain credibility
2. Theinitiatives are broad! Yy
as follows:
classified as peractivity in which the initiative
s aretaken
(a) Power Supply
SCADA(Supervisory contro] &
Data Acquisition
TCMS
(Trouble
Call
ManagementSystems
Micro
Controllers
Supply & Control)
(Power
Data loggers for feeders
(monitoring of power supply &
energy)
-
intelligent
DTRs
(Remote
monitoring & load survey on
feeders)
Mobile
Vans
with. GSM
connectivity’ for very fast
restoration of supply
GIS & GPS
(c) Performance Management
PMRS
(Performance
Monitoring & Review System)
Uploading of PMRS data at
field level and transfer through
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(b) Metering, Billing & Collection
Common Billing System
Spot Billing through hand held
computers
with
GSM
connectivity
Networking
of
Electricity
Revenue Officer with e-Seva
collection Centres
Remote metering with tamper
proof data
for
High - value
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-AMR Systems
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Profite Consumer
(d) Investments for System
Improvement
DISBUT (Software develope
In-House and other advanced
software tools
Integrated
optimum
System
planning for maximum LRVI
(Loss Reduction & Voltage
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FROM THEAMERICAN PEOPLE
Best Practices in Distribution Loss Reduction
Distribution Reform, Upgrades and Management (DRUM) Training Program
8Rae,
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TIMS (Transfer
Management)
Information
Improvement) withleast cost
Prioritisation of works based
on High benefits cost ratio and
least pay back period.
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MIMS (Meter — tracking)
FM
AM
HRD
BCM
Loss Study
Finance Management
Office Automation
The expected results are
-
Loss Reduction
-
Increase in specific revenue
Improvementin Collections
Fast & Better Consumer Servicing
Quick feedback
-
Reduction in interruptions
-
Aboveail Total ConsumerSatisfaction
SCADA- (Supervisory Control and Data Acquisition
SCADAinvolves net working of a group of substations (especially in Metros & large
towns) for data collection in respect.of all equipment at a host station. The distribution
system can be monitored on real time and also controlled by issuing commands to
remote stations where RTUs (Remote terminal units) are located.
The aim of the system is effective load management of the distribution system to
improvereliability and efficiency of supply.
SCADA is more effective .if integrated with load control, AMR, emergency load .
shedding, integrated Var Control, fault location through sectionalisers, trouble call
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management, and.facilities management..
Apart from achieving efficient distribution management, accurate fault analysis and
promptrestoration of supply, it will be possible to identify malfunctioning of equipmentin
advancefor taking corrective action. Historical data for say two years can be sorted for
future analysis.
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IRA,
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Best Practices in Distribution Loss Red
uction
Distribution Reform, Upgrades and Management
(DRUM) Training Program
The system mains comprises of
—
Control Centre equipment
— Application software
— Distribution Management Software
— Communication System
— RTUs forfield data acquisition
—
Ups, etc.
TCMS
The objectives are development of consumers
profile each DTR wise, ‘recoding of
complaints, quick compliance, confirmation of comp
liance, dynamic display of control
system (as a mapdisplay) evaluation of working
patterns and plan work allocation, and
online
information flow to managers.
configuration, location of fuse ofcall offices with
their jurisdiction.
supply system
ee
The Telephone # (say 1912) is allotted as a toll
free connection to cater to the needs of
consumers in a Metropolitan City or a large area
with heavy load density (MW / Sq KM)
CSC (Customer Services Centres) are esta
blished as single point of contact for
redr
essal of all customer grievances including rele
ase of new service connections.
The complaints received and computerized to
be attended as per Citizens charter.
Cases of supplyfailures are communicated to. conc
erned fuse call office or mobile vans
for quick compliance. The communication syst
em updates. status of: compliant and
provides information to administrators through Inter
net based GIS and also priorities the
works to be attended.
GIS mapping and geo referencing and integratio
n with TCMS for development of DTR
based consumer data will greatly help Discoms.
MICRO CONTROLLERS.
Micro controllers are provided at each-of the 33-KV
substations to achieve the following:
- Ensuring number of. hours. of power supp
ly ‘including implementation of
restrictions and control measures when in force
-
Automatic tripping to supplyif load exceeds a pres
et value during specific hours
to avoid over loadi
ng of equipment.
-
Monitoring of uniform distribution of load as per sche
dules
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ee
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-
.
Best Practices in Distribution Loss Reduction
Distribution Reform, Upgrades and Management (DRUM) Training Program
Reading of all events and data ofall parameters is provided generates reports
data of feeder wise hours of supply and also complete data required for
conducting load survey
This logged data can be periodically retrieved through an hand held terminal for post
processing and monitoring apart from report generation. The Micro Controllers work as
per microprocessor based control logic and derives inputs from CTs & PTs of each the
feeders picking up signals and converting them to digital from (A.D converters).
Depending on availability of incoming power supply to SS, and as per pre programmed
time settings, each of the feeder breakers will be enabled or disable for switching ON.
Also at pre-determined timings the circuit breakers will be switched off. Further during
such timings when lighting load is permitted and three phase power loads (such as
pumpsets or LT industry) are not allowed to run, the controllertrips the feeder breakerif
the load exceeds a pre programmedvalue.
e
The microprocessor based control logic has got current and voltage sensors
(CTs & PTs) for each feeder and samples the data on continuous basis,
conditions the signals and converts to digital form for processing, decision
making and logging purpose.
e
Based on incoming poweravailability and based on predefined time settings, the
individual feeders will be enabled for switching ‘on’ and at the end of elapsed
time the same will be tripped ‘off. During the two-phase condition, if the power
drawl exceeds the.rated load, the control mechanism will trip the feeder.
ate
e
The processorlogic also logs all the events and parameters on regular intervals.
e
The logged data can be periodically down loaded to a Hand Held Terminal for
post processing or for report generation.
MBC(Metering, Billing & Collections) ©
CommonBilling
System (CBS
A common software for both HT & LT billing, revenue collection, . New customer
accounting, change of ownership ofservice, dismantlement & termination of service etc
is developed’sothat thé entireMBC function is a commonplatform.
Networking
All Electricity revenue offices and collection centres are networked. The Billing data is
updated on real time basis‘so as to enable consumers to pay their Bills at any of the
collection centres (e-Seva Centres) of the Distribution Company.
fe
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