1. 21st Oct' 05 1
ENERGY CONSERVATION
OPPORTUNITIES
IN POWER DISTRIBUTION SYSTEMS
- a paper presentation at PMI workshop
M.Nageswar Rao,
Engineer,
NTPC Electric Supply Company Ltd.

2. 2
What is Energy conservation
• Energy conservation is the idealistic or
economic practice of reducing the use of
energy by way of
– increasing energy efficiency.
– reducing the energy wastage.

3. 3
Need for EC
• Energy conservation has received attention in India
since the mid 70s.
• The impact of energy conservation efforts are felt at
a very low pace because
– the commercial energy consumption per capita is low in
the country and
– efficient end use devices are costly.
• Structural changes in the economy has led to
expansion of the industrial base in the country, and
subsequently the increase in demand for energy.
• Cost of energy creation through energy
conservation is far less than cost of Energy creation
through installation of power plants.

4. 5
Initiatives taken by India
• MoP developed the strategy to make power available for
all by 2012 includes promotion of energy efficiency and
its conservation in the country, which is found to be the
least cost option to augment the gap between demand and
supply.
• Nearly 25,000 MW of capacity creation through energy
efficiency in the electricity sector alone has been estimated
in India. Energy conservation potential for the economy as
a whole has been assessed as 23%.

5. 6
Initiatives taken by India….continues
• Government of India enacted the Energy Conservation Act,
2001 (52 of 2001)
– which, provides for the legal framework, institutional arrangement and
a regulatory mechanism at the Central and State level to embark upon
energy efficiency drive in the country.
– This act came into force since March, 2002
• MoP also set up Bureau of Energy Efficiency (BEE)
– to institutionalize energy efficiency services, enable delivery
mechanisms in the country and provide leadership to the key players
involved in the energy conservation movement.
– the primary goal of the Bureau is to reduce the energy intensity in
the economy.
– To coordinate with IIPEC (Indian Industry Programme for Energy
Conservation), which forms task forces.
– Also set up DSM cells, pilot projects are under formulation in the
states of Maharasthra and Karnataka

6. 7
Opportunities of concern in EC in
Power Distribution
1. Demand Side Management –DSM
2. Daylight Saving Time - DST
3. Demand Response Programme - DRP
4. Power factor improvement
5. Reconductoring of distribution feeders
6. Transformer Capacity and Location optimization
7. Amorphous core Distribution Transformers
8. Conservation Voltage Reduction- CVR

7. 8
DEMAND SIDE MANAGEMENT
• DSM is any utility-sponsored program designed to
influence customer usage in ways that produce
desired changes in a utility's load shape, i.e.,
– changes in the time pattern and/or
– magnitude of a utility's load.
• It requires network operators to reach "beyond the
meter" to develop more intimate relationships with
the most demanding users.

8. 9
DSM initiatives
1. Peak Clipping or the reduction of the system
peak loads, embodies one of the classic forms of
load management.
• Eg: Direct control of customers' appliances by
utilities at the times of peak load.

9. 10
DSM initiatives..continues
2. Valley Filling encompasses building off-peak
loads. This may be particularly desirable where
the long-run incremental cost is less than the
average price of electricity.
• Eg.: New thermal energy storage (water heating
and/or space heating) that displaces loads served by
fossil fuels.

10. 11
DSM initiatives..continues
3. Load Shifting involves shifting load from on-
peak to off-peak periods.
• Eg.: Use of storage water heating, storage space
heating, cold storage and
• Daylight Saving Time.

11. 12
DSM initiatives..continues
4. Strategic Conservation is the load shape change
that results from utility-stimulated programs
directed at end use consumption.
– This involves a reduction in sales as well as a change
in the pattern of use.

12. 13
DSM initiatives..continues
4.1 Weatherization (Home Weatherization Assistance Program, HWAP is a
Federally funded, low-income residential energy efficiency program that
reduces the energy use of qualified households across the state)
 good heat insulation ( thermocol etc ),
 sun shades,
 orientation of the air-conditioned bed rooms to minimize solar radiation,
 cleaning of air filters in ACs,
 solar films,
 reflective curtain glass,
 automatic door closers,
 Controlled lighting (not all lights on all times, sensor controlled switch off) , use
of natural light etc.
4.2 Energy Efficiency improvement (improving specific energy consumption of
an appliance by changing the technology deployed) like using
 Compact Fluorescent Lamp (CFL),
 Energy efficient pump sets,
 Energy efficient motors etc.

13. 14
DSM initiatives..continues
5. Strategic Load Growth is the load shape change
that refers to a general increase in sales beyond
the valley filling described previously.
– Load growth may involve increased market share of
loads that are, or can be served by competing fuels, as
well as area development.
– Electrification.

14. 15
DSM initiatives..continues
6. Flexible Load Shape is a concept related to
reliability.
– variations of interruptible or curtailable load
– concepts of pooled, integrated energy management
systems
– individual customer load control devices offering
service constraints.

15. 16
DAYLIGHT SAVING TIME
• Daylight Saving Time (DST) Saves Energy
• It’s a form of DSM-Load shifting.
• Energy use and the demand for electricity for
lighting our homes is directly connected to when we
go to bed and when we get up.
• Spring forward, Fall back (by one hour).
• DST is observed in about 70 countries.
DST begins DST ends
U.S.A.(upto 2007) 2 AM First Sunday in April 2 AM Last Sunday in October
U.S.A.(2007 onwards) 2 AM Second Sunday in March 2 AM Last Sunday in November
E.U. 1 AM Last Sunday in March 1 AM Last Sunday in October

16. 17
DST.. continues
• By deploying DST in India too, we can
change working hours of offices of different
regional electrical grids.
• With this peak demand of deficit power
grids can be met by surplus power grids.

17. 18
DEMAND RESPONSE PROGRAMME
• DRP is extension of DSM and load management
concepts.
• These are
– Electric load reductions called for by Independent
System Operators, utilities, or load serving entities
and
– Price response load managed by end-use
customers.
• DR markets have been started in 2001 in New
York Independent System Operator (NYISO)’s
wholesale spot market.

18. 19
DRP....continues
• Demand response - enabling load to be price-
responsive - is essential to assure the efficient
interaction of supply and demand.
Fig.: Wholesale markets today serve inelastic (vertical) demands
with increasingly expensive generation. S-supply, D-Demand.

19. 20
DRP....continues
Fig.: Increasing demand elasticity lowers the cost of meeting
loads, reduces frequency of high price spikes, and reduces
ability of generators to exert market power.

20. 21
DRP initiatives
• Economic load reduction
– Emergency load Curtail –Customers must reduce
their consumption to predetermined levels in
response to directions from system operators. In
exchange for these reductions, customers receive
discounted electricity rates or are paid directly for the
reductions.
– Voluntary demand response programs also pay
customers to reduce their load upon request by
system operators, but the customer does not have a
contractual obligation to curtail their demand.

21. 22
DRP initiatives….. continues
– Demand bidding programs let the customer specify
their own reservation bid for a specified level of load
curtailment. If customer bids are at or below market
clearing prices in the wholesale market, the customer
must reduce demand by this amount and then
receives payment for the reductions.
– Direct load control programs remotely cycle off
customer appliances, such as air conditioners, water
heaters, and pool pumps during times of high peak
demand.
– Interruptible load

22. 23
DRP initiatives….. continues
• Price response load (Demand reduction driven
by market signal)
– Time of use /Interval Meter incentives enable
facilities to participate in load-reduction programs
while also providing critical consumption feedback.
– Real time pricing tariffs expose customers to price
volatility in the wholesale market. Wholesale market
prices are passed through to customers who are
charged on an hourly basis. Customers who can
respond quickly to high prices or shift their
consumption to lower-price periods can reduce their
electricity bills.

23. 24
POWER FACTOR IMPROVEMENT
• Less power factor at loads will cause more current
flows in electric network, resulting
• More losses
• Increased VAR flows, make system more
vulnerable to switching.
• Methods of Power factor improvement
• Penalties to consumers operating at low p.f.
• Installing capacitors in the network, at 11Kv and
L.T. lines.

24. 25
RECONDUCTORING OF
DISTRIBUTION FEEDERS
• In India, most of the 33kV and 11kV
feeders are designed long back and are now
overloaded even upto 50%. This results
heavy ohmic losses in feeders.
• Solution is reconductoring them with
suitable higher rated conductors.
• NESCL is prescribing all old ACSR
conductors to be replaced by AAAC Rabbit
conductor for 11kV feeders.

25. 26
TRANSFORMER CAPACITY &
LOCATION OPTIMIZATION
• Optimization of transformer capacity to the load
demands yields lower transformer losses.
• Bringing the distribution transformer near to load
centre will greatly benefit in reducing the losses.
This involves running H.T. feeders and put small
distribution transformers of capacities 10/ 16 kVA
(1-phase) near the households. This concept is called
High Voltage Distribution System.
• HVDS has been implemented in India in recent
years throughout the country. Additionally, this
increased H.T. feeders results in minimizing
pilferage of electricity.

26. 27
AMORPHOUS CORE
DISTRIBUTION TRANSFORMERS
• Amorphous core is now preferred for
distribution transformers, as it offers very
less losses, almost 80% lesser to that of
conventional transformers.
• NESCL is promoting AMT in very large
scale in all Rural Electrification projects in
India and all other projects.

27. 28
CONSERVATION VOLTAGE
REDUCTION
• Conservation voltage reduction (CVR) consists of
power grid practices and technologies with which
a utility can manage demand by lowering
delivered voltage.
• The objective of CVR is to have the customer’s
voltage at the lowest level consistent with proper
operation of equipment and within levels set by
regulatory agencies and standards setting
organizations.
• CVR has been experimented in U.S.A., California,
Snohomish PUD and several utilities worldwide
for past 20 years.

28. 29
CVR….. continues
• For example, as the voltage supplied to a light
bulb is decreased, the current through the filament
decreases. Since both voltage and current have
been reduced, the energy used by the light bulb is
reduced.
• While the effect of a single light bulb is negligible,
a feeder serving several megawatts of lighting load
presents an opportunity for peak shaving.
• If used only at peak times, voltage reduction falls
into the category of peak clipping. If it is used for
an extended period, it falls into the category of
strategic conservation.

29. 30
CVR….. continues
• Voltage reduction has been proven to
reduce energy consumption, by an overall
factor of 0.8
– meaning that a 1% reduction in voltage results
in, on average, a 0.8% reduction in energy
consumption.

30. 31
Why CVR Is Necessary
• The American National Standards Institute (ANSI) requires that voltage be made
available to residential customers at 120V +/- 5% -- which yields a range of
126V to 114V. Because of line drop, power must be transmitted at a high enough
voltage that the last house on the line gets at least 114V. Consequently, power is
often transmitted at an initial value of 126V. US homes receive an average of
122.5V.

31. 32
Methods of CVR
•Line Drop Compensation (LDC)
– On distribution feeders, Load Tap Changer (LTC) or
Voltage regulator controls are set, so that the end of the line
voltage remains at 114 volts, while the source voltage will
be adjusted as the load varies.
•Voltage Spread Reduction (VSR).
– The voltage limits are narrowed from the ±5% range to
something less, typically ±2.5% using the regulator or LTC.
Some utilities use a combination of these strategies.
These strategies require system studies and computer
modeling of the system. They are engineering intensive,
often requiring expensive load balancing,
reconductoring, and capacitor additions before a utility is
able to implement them.

32. 33
Methods of CVR ….. continues
• Flattened voltage profile is necessary for effective
conservation voltage reduction. This is achieved
with Capacitor Application for Peak Shaving
(CAPS), wherein capacitors are placed at multiple
locations on the distribution circuit.
Fig.: Voltage profiles
at the radial feeder
before the reactive
compensation (dashed
line). After the
compensation is
applied, deeper
reduction is possible
(solid lines) before
reaching the threshold
(lower dotted line).

33. 34
CVR applicable to Indian Power Distribution
….. continues
• The voltage is reduced at 11kV by means of adjusting the
set point of on-load tap changers of 33/11 kV power
transformers at grid substations. So that supply voltage at
end consumers is ensured above 221.5 volts (and addition
of 3 volt to 218.5 Volt; this 3V is to cater for gray zone,
which is the line drop that occurs between the distribution
transformer and your service entrance).
11 kV feeder
11.55-10.45 kV
241.5-218.5 V
Tap control at
33/11 kV
Power
Transformer
11/0.233 kV
DTR
LT Feeder

34. 35
CVR applicable to Indian Power
Distribution
• CVR can also be implemented for light loads (generally from 1am-6am),
where voltage at end consumers will always be in positive tolerance band.
• Supply end voltage can be reduced to the extent possible so as to ensure
10.45 kV at receiving end.
• So, OLTC is to be operated only during night and can be set to usual tap
during day period.
11
kV
11.5
kV
(+5%)
10.45
kV
(-5%) 33/11 kV
Substation
End
11kV.Feeder length DTR
End
Peak day load
Light load (1am to 6am)
Light load (with CVR)10.67kV
(-3%)
Note well that the
energy saving to
customers from
+5% to -3% (241.5
volts down to 223.1
volts) is a 16%
reduction in
consumption for
simple impedance
(resistance) loads.

35. 36
Benefits with CVR
• Operational Benefits
– More even (flat) voltage profile.
– Maintain receiving end voltage within regulatory limits at
all times.
– Better reliability, with reduced load shedding.
– Improves power factor to near unity over the entire feeder
length.
– Reduces line losses.
• Financial Benefits
– Lower kW demand during peak times = cost savings &
increased profitability.
– Buy less power at peak.
– Sell more power at peak.
– Delay or avoid adding peaking generators.

36. 37
Limitations of CVR
• CVR has more effect on residential loads especially
lighting load, but has less or no effect on power
loads. Voltage reduction may increase energy usage
if ‘power’ loads are a significant portion of the total
load.
• Dynamically fluctuating electrical loads limit the
lowest voltage setting.
• Effect of CVR varies with feeder lengths and the mix
of consumer types.
• The presence of particularly sensitive customers,
such as hospitals and manufacturers, on a feeder line
can preclude the entire feeder line from using CVR.

37. 38
Preparation for CVR
• Until now, CVR has been a thoughtful and ambitious notion
that could be implemented only on short feeder lines with
expensive and labor-intensive equipment upgrades.
• CVR can be implemented with the following modifications
of utility equipment
– Modifying tap-changing settings and voltage regulators
– Adding more OLTC voltage regulators
– Adding more capacitors
– Reconfiguring the utility’s central control and communication
systems
– Constructing more substations
– Shortening feeder lines and configuring them with larger conductors
– Reconductoring present feeders
– Converting to higher primary voltages

38. 39
Implementation of CVR
• Between 20 and 25% of US utilities have
tested some form of a CVR program on parts
of their systems and for widely varying
lengths of time.
• In general they have successfully reduced the
average voltage supplied to residential and
some commercial customers about 4%, to
about 117.5V from the average 122.5V.
• Yet CVR is currently applied nationwide to
less than 2% of all feeders, and most of these
are in California, where CVR is mandated.

39. 40
Implementation of CVR… continues
• In India also, CVR can be implemented for
– light loads (morning off-peak and evening off-
peak)
– residential feeders (where residential consumers
are predominant)
– Short feeders where CVR equipment requirement
is less.

40. 41
Jevons Paradox
• The Jevons paradox is an observation made by William Stanley
Jevons who stated that as technological improvements increase
the efficiency with which a resource is used, total consumption
of that resource may increase, rather than decrease.
• It may also be that some conservation efforts have the same
effect.
• For example, if 10% of a country's population reduces its use of
gasoline by 10%, the price of gasoline may drop, and the
remaining 90% of the population may use more gasoline as a
result.
• However, energy conservation is generally regarded as a
beneficial undertaking, if we implement conservation options
which are technical and financial feasible.

41. 42
Thank you all