IMPROVING EFFICIENCY OF TRANSMISSION & DISTRIBUTION.pptx

Presented By:Sanjay Dhokadia (43)

Shaleen Bhola (46)SibaPrasad RanbirSingh (48)

Siddharth Sarangi (49)

IMPROVING EFFICIENCY OF TRANSMISSION & DISTRIBUTION

Contents

Electricity is a concurrent subject in India i.e, both the central and state governments are responsible for the development of the electricity sector.

NTPC, NHPC, THDC, NEEPCO, SJVNL, NLC etc. are the central generation utilities.

POWERGRID is the Central Transmission Utility. At the State level, there are Gencos and Transco in the

respective States.

Present Transmission System of India- An Overview

Power distribution is the final and most crucial link in the electricity supply chain and, unfortunately, the weakest one in the country.

It assumes great significance as the segment has a direct impact on the sector's commercial viability, and ultimately on the consumers who pay for power services.

The sector has been plagued by high distribution losses (30% overall) coupled with theft of electricity, low metering levels and poor financial health of utilities with low cost recovery.

Due to the above, the distribution companies have not been able to undertake corresponding investments in infrastructure augmentation.

Distribution

The distribution segment continues to carry electricity from the point where transmission leaves off, that is, at the 66/33 kV level.

The standard voltages on the distribution side are therefore 66kV, 33 kV, 22 kV, 11 kV and 400/230 volts, besides 6.6 kV, 3.3 kV and 2.2 kV. Depending upon the quantum of power and the distance involved, lines of appropriate voltages are laid. The main distribution equipment comprises HT and LT lines, transformers, substations, switchgears, capacitors, conductors and meters. HT lines supply electricity to industrial consumers while LT lines carry it to residential and commercial consumers.

Overview of the Existing System

India’s transmission network comprises274,882 ckt km of lines383,465 MVA transformer capacity at 220 kV & above

CAGR of 7% between 2007-28 and 2011-12

Twelfth Plan Target 109,440 ckt km lines 270,000 MVA of substation capacity

Statistics

In 2010-11, at least 14 of the 53 unbundled state utilities reported an aggregate AT & C losses of 30% & above.

The aggregate net losses of state utilities is at Rs. 820 billion till 2009-10.

AT&C losses remain woefully high though the restructured APDRP is aiming to bring it to 15 per cent by 2012.

Another problem is poor billing and collection. Of the total electricity generated, less than 50 per cent is paid for.

Tariffs continue to suffer from lack of commercial principles in most cases.

Investment in distribution infrastructure remains lower than what is desirable.

Key Issues

The “business case” for energy efficiency is fairly straightforward: using less energy means paying less for energy.

But a simple cost-benefit analysis might overlook some very important benefits that efficiency brings.

Greater energy efficiency in the T&D system means lower emissions in generation to deliver the same amount of consumed energy.

Fuel conservation and diversity is another strong selling point for efficiency, and here the benefits extend well beyond economic and even environmental considerations. Reducing the dependence on foreign fuel supplies—be they oil, natural gas or even coal—pays obvious dividends from a security standpoint, and the less we use, the less we have to buy.

Benefits of Improved Efficiency

classified into the following three categories:Technologies for expanding transmission capacity to enable

optimal deployment and use of generation resourcesTechnologies for optimizing transmission and distribution

system design and operations to reduce overall energy losses

New industry standards for energy efficiency power apparatus

Technology Options

Reducing T&D energy losses through optimized system design and operation practices

The following are some of the most widely recognized loss reduction techniques in T&D system Design and operation resulting in higher efficiency. Reconducting – replace a conductor with a larger conductor or add

additional conductors in parallel. Voltage upgrades – upgrade a portion of the transmission or

distribution network to a higher voltage level. Voltage optimization through reactive power compensation – install

reactive power resources at chosen locations to Minimize reactive power transfer on the T&D grids. Direct delivery of power to mega load centers through HVDC. Equalizing phase loading – improve the balance of phase currents of

distribution systems.

Technology Options

Distribution is the weakest link in the power supply chain. Huge T&D losses are a major cause of concern.

Distribution reforms and Energy efficiency are inter-linked processes. In order to reduce the T&D losses, and thereby improving energy efficiency, the following measures have to be taken in right earnest.100% metering and AMR:Static (electronic) meters:

Installation of static meters on all 11 KV out-going feeders and distribution transformers (DTs).

Distribution Reforms and Energy Efficiency

Total energy accounting: The energy received in each 11 kV substation and 11 kV

out-going feeders; energy billed and T&D losses at each of the distribution transformer shall be accurately accounted for. The implementation of energy audit and accounting system, with billing unit at subdivision level as the nodal point, the problem of commercial losses can be solved. This will help fix proper responsibility at the sub-divisional, divisional, circle and zonal levels. Installation of capacitor banks and network reconfiguration:

Installation of capacitors at all levels; reconfiguration of feeder lines & distribution transformers in such a way as to reduce the length of LT lines (to reduce technical and commercial losses) and make the system less LT oriented.


High Voltage Distribution System & re-conductoring:Installation of smaller size energy efficient distribution

transformers so that each transformer supplies power to 10 to 15 households only, re-conductoring of over loaded sections; improving HT/ LT line ratio, development of digital mapping of the entire distribution system and load flow studies for better energy management.Effective Management Information System (MIS):

Both feeder and DT static meters will record active energy, power factor and load information. The data recorded in the static meters can be downloaded to a computer network and software packages will be effectively utilized to process the data for meaningful management of the distribution system. An effective MIS ensures effective flow of information to facilitate quick decision-making and to improve the operation and management of the distribution system.


Transmission and distribution of electrical energy require cables and power transformers, which create three types of energy loss:The Joule effect, where energy is lost as heat in the

conductor (a copper wire, for example)Magnetic losses, where energy dissipates into a

magnetic fieldThe dielectric effect, where energy is absorbed in the

insulating material

Technologies With Potential

FACTS DevicesA family of power electronics devices known as Flexible AC

Transmission Systems, or FACTS, provides a variety of benefits for increasing transmission efficiency. Perhaps the most immediate is their ability to allow existing AC lines to be loaded more heavily without increasing the risk of disturbances on the system.

Actual results vary with the characteristics of each installation, but industry experience has shown FACTS devices to enhance transmission capacity by 20-40%. FACTS devices stabilize voltage, and in so doing remove some of the operational safety constraints that prevent operators from loading a given line more heavily. In addition to the efficiency gains, these devices also deliver a clear reliability benefit.


Dynamic voltage control, to enable limiting of over-voltages over long, lightly loaded lines and cable systems, as well as prevent voltage depressions or even collapses in heavily loaded or faulty systems.

Increased power transmission capability and stability of long power corridors, without any need to build new lines. This is a highly attractive option, costing less than new lines, with less time expenditure as well as impact on the environment.

Facilitating connection of renewable generation by maintaining grid stability and fulfilling grid codes, as well as making room for the additional power in existing grids.

Facilitating the building of high speed rail by supporting the feeding grid and maintaining power quality in the point of common connection.

Maintaining power quality in grids dominated by heavy industrial loads such as steel plants and large mining complexes.

Enabling the implementation of Smart Grids.


High Efficiency Transformers:According to the Leonardo ENERGY website, which is the global

community for sustainable energy professionals: “The worldwide electricity savings’estimated to be 200 TWh. This savings potential is not only technically advantageous, but also brings economic is often an economically sound investment decision despite their higher purchase price.” decades.

But because their prices are greater than for ordinary transformers, buyers should estimate the energy savings which can be made during the life cycle of a transformer and then choose the most appropriate one.

These transformers differ from ordinary ones in that they use high quality magnetic material and selected insulating substances and are designed in such a way that they can be cooled down better.


Voltage OptimizationAt the transmission level utilities and Regional Transmission

Operators (RTO) have made extensive investments in real-time and near-real time tools to minimize losses in transmission networks. It is noted that there is extensive metering/ monitoring at the transmission level. As indicate earlier, Reactive Power also contributes to loss; under normal circumstances it is unusual to see significant reactive power flow on transmission lines. Distribution systems are poorly monitored. Thus operational efficiency improvements are achieved by pre planning and through technologies such as controlled capacitor banks.


Voltage Optimization is an analysis and control tool addresses minimizing losses in the distribution system but can also be used to implement CVR from the utility side. The application of the voltage optimization concept has been hindered by the lack of metering in the distribution system. The key issue is that it is critical for any utility side solution to know that customers at the tail end of the system continue to receive adequate voltage. The ongoing smart-meter implementations as well as new technologies that are applied at the service transformer level will allow distribution companies to implement comprehensive voltage optimization and CVR(Conservation Voltage Reduction) programs.


Superconductivity:Most conductors have some degree of resistance which

prevents electricity from flowing effortlessly.Superconductors are materials that have no resistance to

the flow of electricity and mostly this occur at extremely cold temperatures.

With the discovery of new materials superconductivity is happening at 138ºK.


High temperature superconducting cables:Superconducting cables offer the advantage of lower loss,

lighter weight, and more compact dimensions, as compared to conventional cables. In addition to better energy efficiency to utility grid, this can lead to easier and and faster installation of the cable system, fewer linking parts, and reduced use of land. The high performance of superconducting materials leads to reduced materials use and lighter and more compact cable technology. In this way, energy and cost are saved in the whole chain of manufacturing, transport, installation, use and end-of life disposal.


Superconducting transformers: When a transformer is under a loaded condition, Joule heating of the copper

coil adds considerably to the amount of lost energy. Although today’s utility power transformers lose less than 1 % of their total rating in wasted energy, any energy saved within this 1 % represents tremendous potential savings over the expected lifetime of the transformer as they can be in service for decades.

We are all used to seeing copper and aluminium electrical wires and cables, which conduct electricity at ambient temperatures but lose energy due to the Joule effect.

With superconductors, losses due to the Joule effect become essentially zero, thereby creating the potential for dramatic reduction in overall losses.

Even with the added cost of making them cold enough for superconducting, transformers in the 10 MW and higher range are projected top be substantially more efficient and less expensive than their conventional counterparts.


Higher efficiency Transformers / lower resistance conductors: Transformer/Conductor selection has traditionally been based on cost-

benefit analysis, trading off the cost of losses over the life of the asset against capital cost. In recent times the pressure to manage capital expenditures may have worked against efficiency considerations. Resistance can be reduced by using larger conductor which drives up capital cost.

A closely related option is re-conductoring transmission lines. Often driven by the need for additional capacity, emphasizing efficiency can be a synergistic consideration. New types of conductors that are larger in size but retain strength will have a major impact in this area, as will new transformer designs and advanced materials.

Super-conducting transmission, with a wire loss of zero, will also contribute; however the justification will come from other benefits such as increased load carrying capability and system security.


Demand reduction:Any technology that reduces demand or reduces peak

demand (better ‘utilization factor’) produces efficiency benefits throughout the T&D system. Thus demand response programs, distributed energy resources and CVR all have the added benefit of improving transmission efficiency. In fact, the perceived decrease in T&D efficiency are directly attributed to the fact that demand increases in the absence of T&D additions has increased both the peak demand and lowered the utilization factor in T&D.


HVDS Systems: The advantages of HVDS systems are well known, particularly in

containing theft of electricity. Besides, it improves the quality of power significantly and thereby improves customer satisfaction. HVDS systems should be given a special focus to get immediate results in loss reduction.

Efforts also need to be made to bring down the HT/LT ratio during the 11th Plan. The investment on conversions from conventional systems to HVDS is recovered by way of loss reduction within a period of 3 to 5 years in most cases.

Installation of medium voltage distribution (MVD) networks in theft-prone areas, with direct connection of each consumer to the low voltage terminal of the supply transformer.


Gas-Insulated Substations:Most substations occupy large areas of land to

accommodate the design requirements of the given facility. However, each time power flows through a substation to step down the voltage, more energy is lost as the power flows through the transformers, switches and other equipment. The efficiency of the lower-voltage lines coming out of the substation is also markedly lower than their high-voltage counterparts. If power can be transmitted at higher voltage to a substation that is closer to where the energy will be consumed, significant efficiency improvements are possible.


Gas-insulated substations essentially take all of the equipment you would find in an outdoor substation and encapsulate it inside of a metal housing. The air inside is replaced with a special inert gas, which allows all of the components to be placed much closer together without the risk of a flashover. The result is that it is now possible to locate a substation in the basement of a building or other confined space so that the efficiency of high-voltage transmission can be exploited to the fullest extent.

Technologies With Potential(Gas-Insulated Substations)…

Wide Area Monitoring SystemsMuch of the transmission system could feasibly be operated at a higher

loading, were it not for reliability concerns. However, if operators were given the ability to monitor grid conditions more precisely and in real time, some of these constraints would be removed. One example relates to the simple fact that when transmission lines heat up, the metal becomes pliable and the lines sag, which can cause a short circuit if they come into contact with a tree or other grounding object.

Wide area monitoring systems (WAMS) have many promising capabilities, one of which is line thermal monitoring. With this functionality, transmission operators could conceivably change the loading of transmission lines more freely by virtue of having a very clear understanding of how close a given line really is to its thermal limits.


Wireless power TransmissionAdvantages

Wireless Power Transmission system would completely eliminates the existing high-tension power transmission line cables, towers and sub stations between the generating station and consumers and facilitates the interconnection of electrical generation plants on a global scale.

It has more freedom of choice of both receiver and transmitters. Even mobile transmitters and receivers can be chosen for the WPT system.

The cost of transmission and distribution become less and the cost of electrical energy for the consumer also would be reduced.


The power could be transmitted to the places where the wired transmission is not possible.

Loss of transmission is negligible level in the Wireless Power Transmission; therefore, the efficiency of this method is very much higher than the wired transmission.

Power is available at the rectenna as long as the WPT is operating. The power failure due to short circuit and fault on cables would

never exist in the transmission and power theft would be not possible at all.

DisadvantagesThe Capital Cost for practical implementation of WPT seems to be

very high and the other disadvantage of the concept is interference of microwave with present communication systems.

Technologies With Potential (Wireless power Transmission)…

Other notable technologies and design practices that can increase the efficiency of the grid include:More underground distribution lines – these could save up

to 80 percent of distribution lossesDC distribution networksMicrogrids to eliminate long distance transmissionIntelligent automated grid designReal-time online control systemsLoad management through smart meteringEnergy storage devices

Technology Options

IMPROVING EFFICIENCY OF TRANSMISSION & DISTRIBUTION.pptx

Documents

maintaining

voltage optimization

lt lines

transmission

distribution

energy efficiency

distribution

distribution