Electric Transmission

8/6/2019 Electric Transmission

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Electric power transmissionFrom Wikipedia, the free encyclopedia"Electric transmission" redirects here. For vehicle transmissions, see diesel-electrictransmission.

400 kV high-tension transmission lines near Madrid

Electric power transmission or "high voltage electric transmission" is the bulk transfer ofelectrical energy, from generatingpower plantsto substations located near population

centers. This is distinct from the local wiring between high voltage substations andcustomers, which is typically referred to as electric power distribution. Transmission lines,when interconnected with each other, become high voltage transmission networks. In the US,these are typically referred to as "power grids" or just "the grid", while in the UK the networkis known as the "national grid."North America has three major grids: TheWesternInterconnection; The Eastern Interconnection and theElectric Reliability Council of Texas(or ERCOT) grid.

Historically, transmission and distribution lines were owned by the same company, but overthe last decade or so many countries haveliberalizedthe electricity marketin ways that haveled to the separation of the electricity transmission business from the distribution business.[1]

Transmission lines mostly use three-phasealternating current (AC), although single phaseAC is sometimes used in railway electrification systems. High-voltage direct-current(HVDC) technology is used only for very long distances (typically greater than 400 miles, or600 km); submarine power cables (typically longer than 30 miles, or 50 km); or forconnecting two AC networks that are not synchronized.

Electricity is transmitted athigh voltages (110 kV or above) to reduce the energy lost in longdistance transmission. Power is usually transmitted throughoverhead power lines.Underground power transmission has a significantly higher cost and greater operationallimitations but is sometimes used in urban areas or sensitive locations.

A key limitation in the distribution of electricity is that, with minor exceptions, electricalenergy cannot be stored, and therefore must be generated as needed. A sophisticated systemof control is therefore required to ensure electric generation very closely matches the demand.If supply and demand are not in balance, generation plants and transmission equipment can
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shut down which, in the worst cases, can lead to a major regional blackout, such as occurredin California and the US Northwest in 1996 and in the US Northeast in 1965, 1977 and 2003.To reduce the risk of such failures, electric transmission networks are interconnected intoregional, national or continental wide networks thereby providing multiple redundantalternate routes for power to flow should (weather or equipment) failures occur. Much

analysis is done by transmission companies to determine the maximum reliable capacity ofeach line which is mostly less than its physical or thermal limit, to ensure spare capacity isavailable should there be any such failure in another part of the network.

Diagram of an electrical system.

Contents[hide]

1 Overhead transmission

2 Underground transmission

3 History

4 Bulk power transmission 4.1 Grid input

4.2 Losses

4.3 Subtransmission

4.4 Transmission grid exit

5 High-voltage direct current

6 Limitations

7 Control

7.1 Load balancing 7.2 Failure protection

8 Communications

9 Electricity market reform

10 Cost of electric power transmission

11 Merchant transmission

12 Health concerns

13 Government policy

14 Special transmission 14.1 Grids for railways
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14.2 Superconducting cables

14.3 Single wire earth return

14.4 Wireless power transmission

15 Security of control systems

16 Records

17 See also

18 Notes

19 Further reading

20 External links

[edit] Overhead transmissionMain article: Overhead power line

Contiguous United States power transmission grid consists of 300,000 km of lines operated

by 500 companies.High-voltage overhead conductors are not covered by insulation. The conductor material isnearly always an aluminium alloy, made into several strands and possibly reinforced withsteel strands. Copper was sometimes used for overhead transmission but aluminium is lowerin weight for only marginally reduced performance, and much lower in cost. Overheadconductors are a commodity supplied by several companies worldwide. Improved conductormaterial and shapes are regularly used to allow increased capacity and modernizetransmission circuits. Conductor sizes range from 12 mm2 (#6 American wire gauge) to750 mm2 (1,590,000 circular mils area), with varying resistance and current-carryingcapacity. Thicker wires would lead to a relatively small increase in capacity due to the skineffect, that causes most of the current to flow close to the surface of the wire.

Today, transmission-level voltages are usually considered to be 110 kV and above. Lowervoltages such as 66 kV and 33 kV are usually considered subtransmissionvoltages but areoccasionally used on long lines with light loads. Voltages less than 33 kV are usually used fordistribution. Voltages above 230 kV are considered extra high voltage and require differentdesigns compared to equipment used at lower voltages.

Since overhead transmission lines are uninsulated, design of these lines requires minimumclearances to be observed to maintain safety. Adverse weather conditions of high wind andlow temperatures can lead to power outages: wind speeds as low as 23 knots (43 km/h) can

permit conductors to encroach operating clearances, resulting in aflashoverand loss ofsupply.[2] Oscillatory motion of the physical line can be termedgallop orflutterdepending on

the frequency and amplitude of oscillation.
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High Voltage Lines in Washington State

[edit] Underground transmissionMain article: Undergrounding

Electric power can also be transmitted byunderground power cables instead of overheadpower lines.

[edit] History

Main article: History of electric power transmission

New York City streets in 1890. Besides telegraph lines, multiple electric lines were requiredfor each class of device requiring different voltages.

In the early days of commercial electric power, transmission of electric power at the samevoltage as used by lighting and mechanical loads restricted the distance between generating

plant and consumers. In 1882, generation was with direct current (DC), which could noteasily be increased in voltage for long-distance transmission. Different classes of loads (for
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example, lighting, fixed motors, and traction/railway systems) required different voltages,and so used different generators and circuits.[3][page needed]

Due to this specialization of lines and because transmission was so inefficient that generatorsneeded to be near their loads, it seemed at the time that the industry would develop into whatis now known as a distributed generation system with large numbers of small generators

located nearby their loads.[4]

In 1886 in Great Barrington, Massachusetts, a 1kValternating current (AC) distributionsystem was installed. That same year, AC power at 2 kV, transmitted 30 km, was installed atCerchi, Italy. At an AIEE meeting on May 16, 1888,Nikola Tesla delivered a lecture entitled

A New System of Alternating Current Motors and Transformers, describing the equipmentwhich allowed efficient generation and use ofpolyphasealternating currents. Thetransformer, and Tesla's polyphase and single-phase induction motors, were essential for acombined AC distribution system for both lighting and machinery. Ownership of the rights tothe Tesla patents was a key advantage to theWestinghouse Company in offering a completealternating current power system for both lighting and power.

Nikola Tesla's Alternating currentpolyphase generators on display at the 1893 World's Fairin Chicago. Tesla's polyphase innovations revolutionized transmission.

Regarded as one of the most influential electrical innovations, the universal system usedtransformers to step-up voltage from generators to high-voltage transmission lines, and thento step-down voltage to local distribution circuits or industrial customers.[3] By a suitablechoice ofutility frequency, both lighting and motor loads could be served. Rotary convertersand latermercury-arc valves and other rectifier equipment allowed DC to be provided whereneeded. Generating stations and loads using different frequencies could be interconnectedusing rotary converters. By using common generating plants for every type of load, importanteconomies of scalewere achieved, lower overall capital investment was required, load factoron each plant was increased allowing for higher efficiency, a lower cost for the consumer andincreased overall use of electric power.

By allowing multiple generating plants to be interconnected over a wide area, electricityproduction cost was reduced. The most efficient available plants could be used to supply thevarying loads during the day. Reliability was improved and capital investment cost wasreduced, since stand-by generating capacity could be shared over many more customers and awider geographic area. Remote and low-cost sources of energy, such as hydroelectric poweror mine-mouth coal, could be exploited to lower energy production cost.[3]

The first transmission of three-phase alternating current using high voltage took place in 1891during the international electricity exhibitioninFrankfurt. A 25 kV transmission line,approximately 175 km long, connectedLauffen on the Neckarand Frankfurt.

Voltages used for electric power transmission increased throughout the 20th century. By1914, fifty-five transmission systems each operating at more than 70 kV were in service. Thehighest voltage then used was 150 kV.[5]
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The rapid industrialization in the 20th century made electrical transmission lines and grids acritical part of the infrastructure in most industrialized nations. Interconnection of localgeneration plants and small distribution networks was greatly spurred by the requirements ofWorld War I, where large electrical generating plants were built by governments to provide

power to munitions factories. Later these plants were connected to supply civil loads through

long-distance transmission.[6]

[edit] Bulk power transmission

A transmission substation decreases the voltage of incoming electricity, allowing it toconnect from long distance high voltage transmission, to local lower voltage distribution. Italso reroutes power to other transmission lines that serve local markets. A transmissionsubstation may include phase-shifting or voltage regulating transformers. This is thePacifiCorp Hale Substation, Orem, Utah, USA.

Engineers design transmission networks to transport the energy as efficiently as feasible,while at the same time taking into account economic factors, network safety and redundancy.These networks use components such as power lines, cables, circuit breakers, switches andtransformers. The transmission network is usually administered on a regional basis by anentity such as a regional transmission organization ortransmission system operator.

Transmission efficiency is hugely improved by devices that increase the voltage, andproportionately reduce the current in the conductors, thus keeping the power transmittednearly equal to the power input. The reduced current flowing through the line reduces thelosses in the conductors. According to Joule's Law, energy losses are directly proportional tothe square of the current. Thus, reducing the current by a factor of 2 will lower the energy lostto conductor resistance by a factor of 4.

This change in voltage is usually achieved in AC circuits using astep-up transformer.DCsystems require relatively costly conversion equipment which may be economically justified

for particular projects, but are less common currently.A transmission grid is a network ofpower stations, transmission circuits, and substations.Energy is usually transmitted within a grid with three-phaseAC. Single phase AC is usedonly for distribution to end users since it is not usable for large polyphase induction motors.In the 19th century, two-phase transmission was used but required either three wires withunequal currents or four wires. Higher order phase systems require more than three wires, butdeliver marginal benefits.
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The synchronous gridsofEurasia.

The capital cost of electric power stations is so high, and electric demand is so variable, thatit is often cheaper to import some portion of the needed power than to generate it locally.Because nearby loads are often correlated (hot weather in the Southwest portion of the US

might cause many people to use air conditioners), electricity often comes from distantsources. Because of the economics of load balancing, wide area transmission grids now spanacross countries and even large portions of continents. The web of interconnections between

power producers and consumers ensures that power can flow, even if a few links areinoperative.

The unvarying (or slowly varying over many hours) portion of the electric demand is knownas the base loadand is generally served best by large facilities (which are therefore efficientdue to economies of scale) with low variable costs for fuel and operations. Such facilitiesmight be nuclear or coal-fired power stations, or hydroelectric, while other renewable energysources such as concentrated solar thermalandgeothermal powerhave the potential to

provide base load power. Renewable energy sources such as solar photovoltaics, wind, wave,

and tidal are, due to their intermittency, not considered "base load" but can still add power tothe grid. The remaining power demand, if any, is supplied bypeaking power plants, whichare typically smaller, faster-responding, and higher cost sources, such as combined cycle orcombustion turbine plants fueled by natural gas.

A high-power electrical transmission tower.

Long-distance transmission of electricity (thousands of kilometers) is cheap and efficient,with costs of US$0.0050.02/kWh (compared to annual averaged large producer costs ofUS$0.010.025/kWh, retail rates upwards of US$0.10/kWh, and multiples of retail forinstantaneous suppliers at unpredicted highest demand moments).[7] Thus distant supplierscan be cheaper than local sources (e.g., New York City buys a lot of electricity from Canada).Multiple local sources (even if more expensive and infrequently used) can make the

transmission grid more fault tolerant to weather and other disasters that can disconnect distantsuppliers.
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more than a short time. While subtransmission circuits are usually carried onoverhead lines,in urban areas buried cable may be used.

There is no fixed cutoff between subtransmission and transmission, or subtransmission anddistribution. The voltage ranges overlap somewhat. Voltages of 69 kV, 115 kV and 138 kVare often used for subtransmission in North America. As power systems evolved, voltages

formerly used for transmission were used for subtransmission, and subtransmission voltagesbecame distribution voltages. Like transmission, subtransmission moves relatively largeamonts of power, and like distribution, subtransmission covers an area instead of just point to

point. [12]

[edit] Transmission grid exit

At the substations, transformers reduce the voltage to a lower level fordistributiontocommercial and residential users. This distribution is accomplished with a combination ofsub-transmission (33 kV to 132 kV) and distribution (3.3 to 25 kV). Finally, at the point ofuse, the energy is transformed to low voltage (varying by country and customer requirements

see mains power systems).

[edit] High-voltage direct currentMain article: High-voltage direct current

High voltage direct current (HVDC) is used to transmit large amounts of power over longdistances or for interconnections between asynchronous grids. When electrical energy isrequired to be transmitted over very long distances, it is more economical to transmit usingdirect currentinstead ofalternating current. For a long transmission line, the lower losses andreduced construction cost of a DC line can offset the additional cost of converter stations ateach end. Also, at high AC voltages, significant (although economically acceptable) amountsof energy are lost due to corona discharge, thecapacitance between phases or, in the case of

buried cables, between phases and thesoil orwaterin which the cable is buried.

HVDC is also used for long submarine cables because over about 30 km length AC can nolonger be applied. In that case special high voltage cables for DC are built. Many submarinecable connections - up to 600 km length - are in use nowadays.

HVDC links are sometimes used to stabilize against control problems with the AC electricityflow. The power transmitted by an AC line increases as the phase angle between source endvoltage and destination ends increases, but too great a phase angle will allow the generators ateither end of the line to fall out of step. Since the power flow in a DC link is controlledindependently of the phases of the AC networks at either end of the link, this stability limitdoes not apply to a DC line, and it can transfer its full thermal rating. A DC link stabilizes theAC grids at either end, since power flow and phase angle can be controlled independently.

In other words, to transmit AC power as AC when needed in either direction between SeattleandBoston would require the (highly challenging) continuous real-time adjustment of therelativephaseof the two electrical grids. With HVDC instead the interconnection would: (1)Convert AC in Seattle into HVDC. (2) Use HVDC for the three thousand miles of crosscountry transmission. Then (3) convert the HVDC to locally synchronized AC in Boston, andoptionally in other cooperating cities along the transmission route. One prominent example ofsuch a transmission line is the Pacific DC Intertielocated in the Western United States.

[edit] LimitationsThe amount of power that can be sent over a transmission line is limited. The origins of thelimits vary depending on the length of the line. For a short line, the heating of conductors dueto line losses sets a thermal limit. If too much current is drawn, conductors may sag too closeto the ground, or conductors and equipment may be damaged by overheating. For
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intermediate-length lines on the order of 100 km (62 mi), the limit is set by the voltage dropin the line. For longer AC lines, system stability sets the limit to the power that can betransferred. Approximately, the power flowing over an AC line is proportional to the sine ofthe phase angle of the voltage at the receiving and transmitting ends. Since this angle variesdepending on system loading and generation, it is undesirable for the angle to approach 90

degrees. Very approximately, the allowable product of line length and maximum load isproportional to the square of the system voltage. Series capacitors or phase-shiftingtransformers are used on long lines to improve stability. High-voltage direct current lines arerestricted only by thermal and voltage drop limits, since the phase angle is not material totheir operation.

Up to now, it has been almost impossible to foresee the temperature distribution along thecable route, so that the maximum applicable current load was usually set as a compromise

between understanding of operation conditions and risk minimization. The availability ofindustrialDistributed Temperature Sensing (DTS) systems that measure in real timetemperatures all along the cable is a first step in monitoring the transmission system capacity.This monitoring solution is based on using passive optical fibers as temperature sensors,

either integrated directly inside a high voltage cable or mounted externally on the cableinsulation. A solution for overhead lines is also available. In this case the optical fiber isintegrated into the core of a phase wire of overhead transmission lines (OPPC). Theintegrated Dynamic Cable Rating (DCR) or also called Real Time Thermal Rating (RTTR)solution enables not only to continuously monitor the temperature of a high voltage cablecircuit in real time, but to safely utilize the existing network capacity to its maximum.Furthermore it provides the ability to the operator to predict the behavior of the transmissionsystem upon major changes made to its initial operating conditions.

[edit] ControlTo ensure safe and predictable operation the components of the transmission system are

controlled with generators, switches, circuit breakers and loads. The voltage, power,frequency, load factor, and reliability capabilities of the transmission system are designed to

provide cost effective performance for the customers.

[edit] Load balancing

The transmission system provides for base load andpeak load capability, with safety andfault tolerance margins. The peak load times vary by region largely due to the industry mix.In very hot and very cold climates home air conditioning and heating loads have an effect onthe overall load. They are typically highest in the late afternoon in the hottest part of the yearand in mid-mornings and mid-evenings in the coldest part of the year. This makes the powerrequirements vary by the season and the time of day. Distribution system designs always take

the base load and the peak load into consideration.The transmission system usually does not have a large buffering capability to match the loadswith the generation. Thus generation has to be kept matched to the load, to preventoverloading failures of the generation equipment.

Multiple sources and loads can be connected to the transmission system and they must becontrolled to provide orderly transfer of power. In centralized power generation, only localcontrol of generation is necessary, and it involves synchronization of the generation units, to

prevent large transients and overload conditions.

In distributed power generation the generators are geographically distributed and the processto bring them online and offline must be carefully controlled. The load control signals can

either be sent on separate lines or on the power lines themselves. To load balance the voltageand frequency can be used as a signaling mechanism.
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In voltage signaling, the variation of voltage is used to increase generation. The power addedby any system increases as the line voltage decreases. This arrangement is stable in principle.Voltage based regulation is complex to use in mesh networks, since the individualcomponents and setpoints would need to be reconfigured every time a new generator is addedto the mesh.

In frequency signaling, the generating units match the frequency of the power transmissionsystem. Indroop speed control, if the frequency decreases, the power is increased. (The dropin line frequency is an indication that the increased load is causing the generators to slowdown.)

Wind turbines,v2gand other distributed storage and generation systems can be connected tothe power grid, and interact with it to improve system operation.

[edit] Failure protection

Under excess load conditions, the system can be designed to fail gracefully rather than all atonce. Brownoutsoccur when the supply power drops below the demand. Blackoutsoccurwhen the supply fails completely.

Rolling blackouts (also called load shedding) are intentionally engineered electrical poweroutages, used to distribute insufficient power when the demand for electricity exceeds thesupply.

[edit] CommunicationsOperators of long transmission lines require reliable communications forcontrolof the powergrid and, often, associated generation and distribution facilities. Fault-sensingprotectiverelays at each end of the line must communicate to monitor the flow of power into and out ofthe protected line section so that faulted conductors or equipment can be quickly de-energized and the balance of the system restored. Protection of the transmission line from

short circuitsand other faults is usually so critical thatcommon carriertelecommunicationsare insufficiently reliable, and in remote areas a common carrier may not be available.Communication systems associated with a transmission project may use:

Microwaves

Power line communication

Optical fibers

Rarely, and for short distances, a utility will use pilot-wires strung along the transmission linepath. Leased circuits from common carriers are not preferred since availability is not undercontrol of the electric power transmission organization.

Transmission lines can also be used to carry data: this is called power-line carrier, orPLC.PLC signals can be easily received with a radio for the long wave range.Optical fibers can be included in the stranded conductors of a transmission line, in theoverhead shield wires. These cables are known as optical ground wire (OPGW). Sometimes astandalone cable is used, all-dielectric self-supporting (ADSS) cable, attached to thetransmission line cross arms.

Some jurisdictions, such as Minnesota, prohibit energy transmission companies from sellingsurplus communication bandwidth or acting as a telecommunications common carrier. Wherethe regulatory structure permits, the utility can sell capacity in extra dark fibers to a commoncarrier, providing another revenue stream.

[edit] Electricity market reformMain article: Electricity market
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Some regulators regard electric transmission to be a natural monopoly[13] [14] and there aremoves in many countries to separately regulate transmission (see electricity market).

Spain was the first country to establish a regional transmission organization. In that countrytransmission operations and market operations are controlled by separate companies. Thetransmission system operator is Red Elctrica de Espaa (REE) and the wholesale electricity

market operator is Operador del Mercado Ibrico de Energa - Polo Espaol, S.A. (OMEL)[2]. Spain's transmission system is interconnected with those of France, Portugal, andMorocco.

In the United States and parts of Canada, electrical transmission companies operateindependently of generation and distribution companies.

[edit] Cost of electric power transmissionThe cost of high voltage electricity transmission (as opposed to the costs ofelectricitydistribution) is comparatively low, compared to all other costs arising in a consumer'selectricity bill. In the UK transmission costs are about 0.2p/kWh compared to a delivered

domestic price of around 10 p/kWh.

[15]

Research evaluates the level of capital expenditure in the electric power T&D equipmentmarket will be worth $128.9bn in 2011. [16]

[edit] Merchant transmissionMerchant transmission is an arrangement where a third party constructs and operateselectric transmission lines through the franchise area of an unrelated utility. Advocates ofmerchant transmission[who?] claim that this will create competition to construct the mostefficient and lowest cost additions to the transmission grid. Merchant transmission projectstypically involve DC lines because it is easier to limit flows to paying customers.

Operating merchant transmission projects in the United States include theCross Sound Cablefrom Long Island, New YorktoNew Haven, Connecticut, Neptune RTS Transmission Linefrom Sayreville, N.J., to Newbridge, N.Y, ITC Holdings, Inc. transmission system in themidwest, and Path 15 in California. Additional projects are in development or have been

proposed throughout the United States.

There is only one unregulated or market interconnector in Australia:BasslinkbetweenTasmania and Victoria. Two DC links originally implemented as market interconnectorsDirectlinkand Murraylinkhave been converted to regulated interconnectors.NEMMCO

A major barrier to wider adoption of merchant transmission is the difficulty in identifyingwho benefits from the facility so that the beneficiaries will pay the toll. Also, it is difficult fora merchant transmission line to compete when the alternative transmission lines are

subsidized by other utility businesses.[17]

[edit] Health concernsMain article: Electromagnetic radiation and health

Thepreponderance of evidence does not suggest that the low-power, low-frequency,electromagnetic radiation associated with household current constitutes a short or long termhealth hazard. Some studies have found statistical correlations between various diseases andliving or working near power lines, but no adverse health effects have been substantiated for

people not living close to powerlines.[18]

There are established biological effects foracutehigh level exposure to magnetic fields well

above 100 T. In a residential setting, there is "limited evidence of carcinogenicity in humansand less than sufficient evidence for carcinogenicity in experimental animals", in particular,
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childhood leukaemia, associated with average exposure to residential power-frequencymagnetic field above 0.3 to 0.4 T. These levels exceed average residential power-frequencymagnetic fields in homes which are about 0.07 T in Europe and 0.11 T in North America.[19][20]

[edit] Government policyHistorically, local governments have exercised authority over the grid and have significantdisincentives to take action that would benefit states other than their own. Localities withcheap electricity have a disincentive to making interstate commerce in electricity tradingeasier, since other regions will be able to compete for local energy and drive up rates. Someregulators in Maine for example do not wish to address congestion problems because thecongestion serves to keep Maine rates low.[21] Further, vocal local constituencies can block orslow permitting by pointing to visual impact, environmental, and perceived health concerns.In the US, generation is growing 4 times faster than transmission, but big transmissionupgrades require the coordination of multiple states, a multitude of interlocking permits, andcooperation between a significant portion of the 500 companies that own the grid. From a

policy perspective, the control of the grid isbalkanized, and even formerenergy secretaryBill Richardson refers to it as a third world grid. There have been efforts in the EU and US toconfront the problem. The US national security interest in significantly growing transmissioncapacity drove passage of the 2005 energy act giving the Department of Energy the authorityto approve transmission if states refuse to act. However, soon after using its power todesignate twoNational Interest Electric Transmission Corridors, 14 senators signed a letterstating the DOE was being too aggressive.[22]

[edit] Special transmission

[edit] Grids for railways

Main article: Traction power network

In some countries where electric trains run on low frequency AC (e.g., 16.7 Hz and 25 Hz)power, there are separate single phase traction power networks operated by the railways.These grids are fed by separate generators in sometraction powerstations or by tractioncurrent converter plants from the public three phase AC network.

[edit] Superconducting cables

High-temperature superconductors promise to revolutionize power distribution by providinglossless transmission of electrical power. The development of superconductors with transitiontemperatures higher than the boiling point ofliquid nitrogen has made the concept ofsuperconducting power lines commercially feasible, at least for high-load applications.[23] Ithas been estimated that the waste would be halved using this method, since the necessaryrefrigeration equipment would consume about half the power saved by the elimination of themajority of resistive losses. Some companies such as Consolidated Edison and AmericanSuperconductorhave already begun commercial production of such systems.[24] In onehypothetical future system called a SuperGrid, the cost of cooling would be eliminated bycoupling the transmission line with a liquid hydrogen pipeline.

Superconducting cables are particularly suited to high load density areas such as the businessdistrict of large cities, where purchase of an easement for cables would be very costly.[25]

[edit] Single wire earth return

Main article: Single-wire earth return

Single-wire earth return (SWER) or single wire ground return is a single-wire transmissionline for supplying single-phase electrical power for an electrical grid to remote areas at low
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cost. It is principally used for rural electrification, but also finds use for larger isolated loadssuch as water pumps, and light rail. Single wire earth return is also used for HVDC oversubmarine power cables.

[edit] Wireless power transmission

Main article: Wireless energy transferBothNikola Tesla andHidetsugu Yagi attempted to devise systems for large scale wirelesspower transmission, with no commercial success.

Wireless power transmission has been studied for transmission of power from solar powersatellites to the earth. A high power array ofmicrowave transmitters would beam power to arectenna. Major engineering and economic challenges face any solar power satellite project.

[edit] Security of control systemsThe Federal government of the United States admits that the power grid is susceptible tocyber-warfare.[26][27] The United States Department of Homeland Security works with industryto identify vulnerabilities and to help industry enhance the security of control systemnetworks, the federal government is also working to ensure that security is built in as the U.S.develops the next generation of 'smart grid' networks.[28]

[edit] Records Highest capacity system: 6.3 GW HVDC Itaipu (Brazil) (600 kV DC)[29]

Highest transmission voltage (AC): 1.15 MV on Powerline Ekibastuz-Kokshetau(Kazakhstan)

Largest double-circuit transmission, Kita-Iwaki Powerline.

Highestpylons: Yangtze River Crossing (height: 345 m/1,132 ft)

Longest power line: Inga-Shaba (length: 1,700 kilometres / 1,056 miles) Longest span of power line: 5,376 m (17,638 ft) at Ameralik Span

Longest submarine cables:

NorNed,North Sea - (length of submarine cable: 580 kilometres / 360 miles)

Basslink,Bass Strait - (length of submarine cable: 290 kilometres / 180 miles,total length: 370.1 kilometres / 230 miles)

Baltic-Cable, Baltic Sea - (length of submarine cable: 238 kilometres / 148miles, HVDC length: 250 kilometres / 155 miles, total length: 262 kilometres /163 miles)

Longest underground cables: Murraylink, Riverland/Sunraysia - (length of underground cable: 180

kilometres / 112 miles)

[edit] See also

Energy portal

Conductor marking lights

Dynamic demand (electric

power)

Mains electricity

Mains power around the world (list of voltage by

country)
http://en.wikipedia.org/w/index.php?title=Electric_power_transmission&action=edit&section=24http://en.wikipedia.org/wiki/Wireless_energy_transferhttp://en.wikipedia.org/wiki/Nikola_Teslahttp://en.wikipedia.org/wiki/Nikola_Teslahttp://en.wikipedia.org/wiki/Hidetsugu_Yagihttp://en.wikipedia.org/wiki/Hidetsugu_Yagihttp://en.wikipedia.org/wiki/Solar_power_satellitehttp://en.wikipedia.org/wiki/Solar_power_satellitehttp://en.wikipedia.org/wiki/Microwavehttp://en.wikipedia.org/wiki/Microwavehttp://en.wikipedia.org/wiki/Rectennahttp://en.wikipedia.org/w/index.php?title=Electric_power_transmission&action=edit&section=25http://en.wikipedia.org/wiki/Federal_government_of_the_United_Stateshttp://en.wikipedia.org/wiki/Cyber-warfarehttp://en.wikipedia.org/wiki/Cyber-warfarehttp://en.wikipedia.org/wiki/United_States_Department_of_Homeland_Securityhttp://en.wikipedia.org/w/index.php?title=Electric_power_transmission&action=edit&section=26http://en.wikipedia.org/wiki/HVDC_Itaipuhttp://en.wikipedia.org/wiki/Powerline_Ekibastuz-Kokshetauhttp://en.wikipedia.org/wiki/Kita-Iwaki_Powerlinehttp://en.wikipedia.org/wiki/Electricity_pylonhttp://en.wikipedia.org/wiki/Electricity_pylonhttp://en.wikipedia.org/wiki/Yangtze_River_Crossinghttp://en.wikipedia.org/wiki/Inga-Shabahttp://en.wikipedia.org/wiki/Ameralik_Spanhttp://en.wikipedia.org/wiki/NorNedhttp://en.wikipedia.org/wiki/North_Seahttp://en.wikipedia.org/wiki/Basslinkhttp://en.wikipedia.org/wiki/Bass_Straithttp://en.wikipedia.org/wiki/Bass_Straithttp://en.wikipedia.org/wiki/Baltic-Cablehttp://en.wikipedia.org/wiki/Baltic_Seahttp://en.wikipedia.org/wiki/HVDChttp://en.wikipedia.org/wiki/Murraylinkhttp://en.wikipedia.org/wiki/Riverlandhttp://en.wikipedia.org/wiki/Sunraysiahttp://en.wikipedia.org/w/index.php?title=Electric_power_transmission&action=edit&section=27http://en.wikipedia.org/wiki/Portal:Energyhttp://en.wikipedia.org/wiki/Conductor_marking_lightshttp://en.wikipedia.org/wiki/Dynamic_demand_(electric_power)http://en.wikipedia.org/wiki/Dynamic_demand_(electric_power)http://en.wikipedia.org/wiki/Mains_electricityhttp://en.wikipedia.org/wiki/Mains_power_around_the_worldhttp://en.wikipedia.org/wiki/File:Crystal_energy.svghttp://en.wikipedia.org/w/index.php?title=Electric_power_transmission&action=edit&section=24http://en.wikipedia.org/wiki/Wireless_energy_transferhttp://en.wikipedia.org/wiki/Nikola_Teslahttp://en.wikipedia.org/wiki/Hidetsugu_Yagihttp://en.wikipedia.org/wiki/Solar_power_satellitehttp://en.wikipedia.org/wiki/Solar_power_satellitehttp://en.wikipedia.org/wiki/Microwavehttp://en.wikipedia.org/wiki/Rectennahttp://en.wikipedia.org/w/index.php?title=Electric_power_transmission&action=edit&section=25http://en.wikipedia.org/wiki/Federal_government_of_the_United_Stateshttp://en.wikipedia.org/wiki/Cyber-warfarehttp://en.wikipedia.org/wiki/United_States_Department_of_Homeland_Securityhttp://en.wikipedia.org/w/index.php?title=Electric_power_transmission&action=edit&section=26http://en.wikipedia.org/wiki/HVDC_Itaipuhttp://en.wikipedia.org/wiki/Powerline_Ekibastuz-Kokshetauhttp://en.wikipedia.org/wiki/Kita-Iwaki_Powerlinehttp://en.wikipedia.org/wiki/Electricity_pylonhttp://en.wikipedia.org/wiki/Yangtze_River_Crossinghttp://en.wikipedia.org/wiki/Inga-Shabahttp://en.wikipedia.org/wiki/Ameralik_Spanhttp://en.wikipedia.org/wiki/NorNedhttp://en.wikipedia.org/wiki/North_Seahttp://en.wikipedia.org/wiki/Basslinkhttp://en.wikipedia.org/wiki/Bass_Straithttp://en.wikipedia.org/wiki/Baltic-Cablehttp://en.wikipedia.org/wiki/Baltic_Seahttp://en.wikipedia.org/wiki/HVDChttp://en.wikipedia.org/wiki/Murraylinkhttp://en.wikipedia.org/wiki/Riverlandhttp://en.wikipedia.org/wiki/Sunraysiahttp://en.wikipedia.org/w/index.php?title=Electric_power_transmission&action=edit&section=27http://en.wikipedia.org/wiki/Portal:Energyhttp://en.wikipedia.org/wiki/Conductor_marking_lightshttp://en.wikipedia.org/wiki/Dynamic_demand_(electric_power)http://en.wikipedia.org/wiki/Dynamic_demand_(electric_power)http://en.wikipedia.org/wiki/Mains_electricityhttp://en.wikipedia.org/wiki/Mains_power_around_the_world


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Demand response

Distributed generation

Double-circuittransmission line

Electricity distribution Electricity market

Electricity pylon

ElectromagneticTransients Program(EMTP)

Flexible AC transmissionsystem (FACTS)

Geomagnetically induced

current, (GIC) Green power grid

Grid-tied electrical system

High-voltage direct current(HVDC)

Infrastructure

List of high voltageunderground andsubmarine cables

Load profile

Miesbach-Munich Power Transmission

Off-the-grid, living without public utility

Overhead power line

Power line communications (PLC)

Power System Harmonics

Power outage

Radio frequency power transmission

Relative cost of electricity generated by differentsources

Submarine power cable

Traction current

Traction power network

Three-phase electric power V2G

Wheeling (electric power transmission)

Wireless energy transfer

25Hz Power Transmission System

[edit] Notes1. ^ (pdf)A Primer on Electric Utilities, Deregulation, and Restructuring of U.S.

Electricity Markets.United States Department of EnergyFederal Energy ManagementProgram (FEMP). 2002-05. Retrieved December 27, 2008.

2. ^ Hans Dieter Betz, Ulrich Schumann, Pierre Laroche (2009). Lightning: Principles,Instruments and Applications.Springer, pp. 202-203. ISBN 9781402090783.Retrieved on May 13, 2009.

3. ^ abcThomas P. Hughes (1993).Networks of Power: Electrification in WesternSociety, 1880-1930. Baltimore: Johns Hopkins University Press. pp. 119122.ISBN0801846145.

4. ^National Council on Electricity Policy (pdf).Electricity Transmission: A primer.

5. ^ Bureau of Census data reprinted in Hughes, pp. 282-283

6. ^ Hughes, pp. 293-295

7. ^ "Present Limits of Very Long Distance Transmission Systems"

8. ^ Hutchingson, Alex. "The New Energy Fixes: 10 Fixes."Popular Mechanics. June2011: 73. Print.

9. ^ California Public Utilities Commission Corona and induced currents
http://en.wikipedia.org/wiki/Demand_responsehttp://en.wikipedia.org/wiki/Distributed_generationhttp://en.wikipedia.org/wiki/Double-circuit_transmission_linehttp://en.wikipedia.org/wiki/Double-circuit_transmission_linehttp://en.wikipedia.org/wiki/Electricity_distributionhttp://en.wikipedia.org/wiki/Electricity_markethttp://en.wikipedia.org/wiki/Electricity_pylonhttp://en.wikipedia.org/wiki/Emtphttp://en.wikipedia.org/wiki/Emtphttp://en.wikipedia.org/wiki/Flexible_AC_transmission_systemhttp://en.wikipedia.org/wiki/Flexible_AC_transmission_systemhttp://en.wikipedia.org/wiki/Geomagnetically_induced_currenthttp://en.wikipedia.org/wiki/Geomagnetically_induced_currenthttp://en.wikipedia.org/wiki/GIChttp://en.wikipedia.org/wiki/Green_power_gridhttp://en.wikipedia.org/wiki/Grid-tied_electrical_systemhttp://en.wikipedia.org/wiki/High-voltage_direct_currenthttp://en.wikipedia.org/wiki/Infrastructurehttp://en.wikipedia.org/wiki/List_of_high_voltage_underground_and_submarine_cableshttp://en.wikipedia.org/wiki/List_of_high_voltage_underground_and_submarine_cableshttp://en.wikipedia.org/wiki/List_of_high_voltage_underground_and_submarine_cableshttp://en.wikipedia.org/wiki/Load_profilehttp://en.wikipedia.org/wiki/Miesbach-Munich_Power_Transmissionhttp://en.wikipedia.org/wiki/Off-the-gridhttp://en.wikipedia.org/wiki/Overhead_power_linehttp://en.wikipedia.org/wiki/Power_line_communicationhttp://en.wikipedia.org/wiki/Power_system_harmonicshttp://en.wikipedia.org/wiki/Power_outagehttp://en.wikipedia.org/wiki/Radio_frequency_power_transmissionhttp://en.wikipedia.org/wiki/Relative_cost_of_electricity_generated_by_different_sourceshttp://en.wikipedia.org/wiki/Relative_cost_of_electricity_generated_by_different_sourceshttp://en.wikipedia.org/wiki/Submarine_power_cablehttp://en.wikipedia.org/wiki/Traction_currenthttp://en.wikipedia.org/wiki/Traction_power_networkhttp://en.wikipedia.org/wiki/Three-phase_electric_powerhttp://en.wikipedia.org/wiki/V2Ghttp://en.wikipedia.org/wiki/Wheeling_(electric_power_transmission)http://en.wikipedia.org/wiki/Wireless_energy_transferhttp://en.wikipedia.org/wiki/25Hz_Power_Transmission_Systemhttp://en.wikipedia.org/w/index.php?title=Electric_power_transmission&action=edit&section=28http://www1.eere.energy.gov/femp/pdfs/primer.pdfhttp://www1.eere.energy.gov/femp/pdfs/primer.pdfhttp://www1.eere.energy.gov/femp/pdfs/primer.pdfhttp://en.wikipedia.org/wiki/United_States_Department_of_Energyhttp://en.wikipedia.org/wiki/Federal_Energy_Management_Programhttp://en.wikipedia.org/wiki/Federal_Energy_Management_Programhttp://en.wikipedia.org/wiki/Special:BookSources/9781402090783http://en.wikipedia.org/wiki/Thomas_P._Hugheshttp://books.google.com/?id=g07Q9M4agp4C&pg=PA122&lpg=PA122&dq=westinghouse+%22universal+system%22http://books.google.com/?id=g07Q9M4agp4C&pg=PA122&lpg=PA122&dq=westinghouse+%22universal+system%22http://en.wikipedia.org/wiki/International_Standard_Book_Numberhttp://en.wikipedia.org/wiki/Special:BookSources/0801846145http://en.wikipedia.org/wiki/Special:BookSources/0801846145http://www.oe.energy.gov/DocumentsandMedia/primer.pdfhttp://www.geni.org/globalenergy/library/technical-articles/transmission/cigre/present-limits-of-very-long-distance-transmission-systems/index.shtmlhttp://www.cpuc.ca.gov/environment/info/aspen/deltasub/pea/16_corona_and_induced_currents.pdfhttp://en.wikipedia.org/wiki/Demand_responsehttp://en.wikipedia.org/wiki/Distributed_generationhttp://en.wikipedia.org/wiki/Double-circuit_transmission_linehttp://en.wikipedia.org/wiki/Double-circuit_transmission_linehttp://en.wikipedia.org/wiki/Electricity_distributionhttp://en.wikipedia.org/wiki/Electricity_markethttp://en.wikipedia.org/wiki/Electricity_pylonhttp://en.wikipedia.org/wiki/Emtphttp://en.wikipedia.org/wiki/Emtphttp://en.wikipedia.org/wiki/Flexible_AC_transmission_systemhttp://en.wikipedia.org/wiki/Flexible_AC_transmission_systemhttp://en.wikipedia.org/wiki/Geomagnetically_induced_currenthttp://en.wikipedia.org/wiki/Geomagnetically_induced_currenthttp://en.wikipedia.org/wiki/GIChttp://en.wikipedia.org/wiki/Green_power_gridhttp://en.wikipedia.org/wiki/Grid-tied_electrical_systemhttp://en.wikipedia.org/wiki/High-voltage_direct_currenthttp://en.wikipedia.org/wiki/Infrastructurehttp://en.wikipedia.org/wiki/List_of_high_voltage_underground_and_submarine_cableshttp://en.wikipedia.org/wiki/List_of_high_voltage_underground_and_submarine_cableshttp://en.wikipedia.org/wiki/List_of_high_voltage_underground_and_submarine_cableshttp://en.wikipedia.org/wiki/Load_profilehttp://en.wikipedia.org/wiki/Miesbach-Munich_Power_Transmissionhttp://en.wikipedia.org/wiki/Off-the-gridhttp://en.wikipedia.org/wiki/Overhead_power_linehttp://en.wikipedia.org/wiki/Power_line_communicationhttp://en.wikipedia.org/wiki/Power_system_harmonicshttp://en.wikipedia.org/wiki/Power_outagehttp://en.wikipedia.org/wiki/Radio_frequency_power_transmissionhttp://en.wikipedia.org/wiki/Relative_cost_of_electricity_generated_by_different_sourceshttp://en.wikipedia.org/wiki/Relative_cost_of_electricity_generated_by_different_sourceshttp://en.wikipedia.org/wiki/Submarine_power_cablehttp://en.wikipedia.org/wiki/Traction_currenthttp://en.wikipedia.org/wiki/Traction_power_networkhttp://en.wikipedia.org/wiki/Three-phase_electric_powerhttp://en.wikipedia.org/wiki/V2Ghttp://en.wikipedia.org/wiki/Wheeling_(electric_power_transmission)http://en.wikipedia.org/wiki/Wireless_energy_transferhttp://en.wikipedia.org/wiki/25Hz_Power_Transmission_Systemhttp://en.wikipedia.org/w/index.php?title=Electric_power_transmission&action=edit&section=28http://www1.eere.energy.gov/femp/pdfs/primer.pdfhttp://www1.eere.energy.gov/femp/pdfs/primer.pdfhttp://en.wikipedia.org/wiki/United_States_Department_of_Energyhttp://en.wikipedia.org/wiki/Federal_Energy_Management_Programhttp://en.wikipedia.org/wiki/Federal_Energy_Management_Programhttp://en.wikipedia.org/wiki/Special:BookSources/9781402090783http://en.wikipedia.org/wiki/Thomas_P._Hugheshttp://books.google.com/?id=g07Q9M4agp4C&pg=PA122&lpg=PA122&dq=westinghouse+%22universal+system%22http://books.google.com/?id=g07Q9M4agp4C&pg=PA122&lpg=PA122&dq=westinghouse+%22universal+system%22http://en.wikipedia.org/wiki/International_Standard_Book_Numberhttp://en.wikipedia.org/wiki/Special:BookSources/0801846145http://www.oe.energy.gov/DocumentsandMedia/primer.pdfhttp://www.geni.org/globalenergy/library/technical-articles/transmission/cigre/present-limits-of-very-long-distance-transmission-systems/index.shtmlhttp://www.cpuc.ca.gov/environment/info/aspen/deltasub/pea/16_corona_and_induced_currents.pdf


16/20

10.^ ab"Where can I find data on electricity transmission and distribution losses?".Frequently Asked Questions Electricity. U.S. Energy Information Administration.2009-11-19. Retrieved 2011-03-29.

11.^ L. Paris et al. (1984). "Present Limits of Very Long Distance TransmissionSystems". CIGRE.Global Energy Network Institute. Retrieved 2011-03-29.

12.^ Donald G. Fink and H. Wayne Beaty, Standard Handbook for Electrical Engineers(15th Edition) McGraw-Hill, 2007 ISBN 978-0-07-144146-9section 18.5

13.^ Raghuvir Srinivasan (August 15, 2004). "Power transmission business is a naturalmonopoly". The Hindu Business Line. The Hindu. Retrieved January 31, 2008.

14.^ Lynne Kiesling (August 18, 2003). "Rethink the Natural Monopoly Justification ofElectricity Regulation". Reason Foundation. Retrieved January 31, 2008.

15.^ http://www.claverton-energy.com/what-is-the-cost-per-kwh-of-bulk-transmission-national-grid-in-the-uk-note-this-excludes-distribution-costs.htmlWhat is the cost perkWh of bulk transmission / National Grid in the UK (note this excludes distributioncosts)

16.^ visiongain The Electric Power Transmission & Distribution (T&D) EquipmentMarket 2011-2021 http://www.visiongain.com/Report/626/The-Electric-Power-Transmission-and-Distribution-(T-D)-Equipment-Market-2011-2021

17.^ Fiona Woolf (February 2003). Global Transmission Expansion. Pennwell Books.pp. 226, 247. ISBN0-87814-862-0.

18.^ Electromagnetic fields and public health, World Health Organization

19.^ "Electromagnetic fields and public health".Fact sheet No. 322.World HealthOrganization. June 2007. Retrieved 2008-01-23.

20.^ "Electric and Magnetic Fields Associated with the Use of Power" (PDF).National

Institute of Environmental Health Sciences. 2002-06. Retrieved 2008-01-29.21.^National Council on Electricity Policy (pdf).Electricity Transmission: A primer. p.

32 (41 in pdf).

22.^ Wald, Matthew (August 27, 2008). Wind Energy Bumps Into Power Grid's Limits.New York Times. p. A1. Retrieved December 12, 2008.

23.^ Jacob Oestergaard et al.,Energy losses of superconducting power transmissioncables in the grid, [1]

24.^ 600m superconducting electricity line layed in New York

25.^ http://www.futureenergies.com/print.php?sid=237

26.^ BBC: Spies 'infiltrate US power grid'27.^ CNN: Video

28.^ Reuters: US concerned power grid vulnerable to cyber-attack

29.^ "Energy Systems, Environment and Development".Advanced TechnologyAssessment Systems (Global Energy Network Institute) (6). Autumn 1991. RetrievedDecember 27, 2008.

[edit] Further reading Grigsby, L. L., et al. The Electric Power Engineering Handbook. USA: CRC Press.

(2001). ISBN 0-8493-8578-4
http://tonto.eia.doe.gov/tools/faqs/faq.cfm?id=105&t=3http://en.wikipedia.org/wiki/U.S._Energy_Information_Administrationhttp://en.wikipedia.org/wiki/U.S._Energy_Information_Administrationhttp://www.geni.org/globalenergy/library/technical-articles/transmission/cigre/present-limits-of-very-long-distance-transmission-systems/index.shtmlhttp://www.geni.org/globalenergy/library/technical-articles/transmission/cigre/present-limits-of-very-long-distance-transmission-systems/index.shtmlhttp://en.wikipedia.org/wiki/CIGREhttp://en.wikipedia.org/wiki/CIGREhttp://en.wikipedia.org/wiki/Global_Energy_Network_Institutehttp://en.wikipedia.org/wiki/Special:BookSources/9780071441469http://en.wikipedia.org/wiki/Special:BookSources/9780071441469http://www.thehindubusinessline.com/iw/2004/08/15/stories/2004081501201300.htmhttp://www.thehindubusinessline.com/iw/2004/08/15/stories/2004081501201300.htmhttp://www.reason.org/commentaries/kiesling_20030818b.shtmlhttp://www.reason.org/commentaries/kiesling_20030818b.shtmlhttp://www.claverton-energy.com/what-is-the-cost-per-kwh-of-bulk-transmission-national-grid-in-the-uk-note-this-excludes-distribution-costs.htmlhttp://www.claverton-energy.com/what-is-the-cost-per-kwh-of-bulk-transmission-national-grid-in-the-uk-note-this-excludes-distribution-costs.htmlhttp://www.claverton-energy.com/what-is-the-cost-per-kwh-of-bulk-transmission-national-grid-in-the-uk-note-this-excludes-distribution-costs.htmlhttp://www.visiongain.com/Report/626/The-Electric-Power-Transmission-and-Distribution-(T-D)-Equipment-Market-2011-2021http://www.visiongain.com/Report/626/The-Electric-Power-Transmission-and-Distribution-(T-D)-Equipment-Market-2011-2021http://en.wikipedia.org/wiki/International_Standard_Book_Numberhttp://en.wikipedia.org/wiki/Special:BookSources/0-87814-862-0http://en.wikipedia.org/wiki/Special:BookSources/0-87814-862-0http://www.who.int/mediacentre/factsheets/fs322/en/index.htmlhttp://en.wikipedia.org/wiki/World_Health_Organizationhttp://www.who.int/mediacentre/factsheets/fs322/en/index.htmlhttp://en.wikipedia.org/wiki/World_Health_Organizationhttp://en.wikipedia.org/wiki/World_Health_Organizationhttp://en.wikipedia.org/wiki/World_Health_Organizationhttp://www.niehs.nih.gov/health/docs/emf-02.pdfhttp://en.wikipedia.org/wiki/National_Institute_of_Environmental_Health_Scienceshttp://en.wikipedia.org/wiki/National_Institute_of_Environmental_Health_Scienceshttp://www.oe.energy.gov/DocumentsandMedia/primer.pdfhttp://www.nytimes.com/2008/08/27/business/27grid.html?_r=2&ref=business&oref=sloginhttp://en.wikipedia.org/wiki/New_York_Timeshttp://en.wikipedia.org/wiki/New_York_Timeshttp://www.supercables.com/Reference/tabsartikel.pdfhttp://www.newscientist.com/article/dn11907-superconducting-power-line-to-shore-up-new-york-grid.htmlhttp://www.futureenergies.com/print.php?sid=237http://news.bbc.co.uk/2/hi/technology/7990997.stmhttp://in.reuters.com/article/oilRpt/idINN0853911920090408http://www.geni.org/globalenergy/library/technical-articles/transmission/united-nations/center-for-science-and-technology-for-development/advanced-technology-assessment-system/energy-systems-environment-and-development.shtmlhttp://en.wikipedia.org/w/index.php?title=Electric_power_transmission&action=edit&section=29http://en.wikipedia.org/wiki/Special:BookSources/0849385784http://tonto.eia.doe.gov/tools/faqs/faq.cfm?id=105&t=3http://en.wikipedia.org/wiki/U.S._Energy_Information_Administrationhttp://www.geni.org/globalenergy/library/technical-articles/transmission/cigre/present-limits-of-very-long-distance-transmission-systems/index.shtmlhttp://www.geni.org/globalenergy/library/technical-articles/transmission/cigre/present-limits-of-very-long-distance-transmission-systems/index.shtmlhttp://en.wikipedia.org/wiki/CIGREhttp://en.wikipedia.org/wiki/Global_Energy_Network_Institutehttp://en.wikipedia.org/wiki/Special:BookSources/9780071441469http://www.thehindubusinessline.com/iw/2004/08/15/stories/2004081501201300.htmhttp://www.thehindubusinessline.com/iw/2004/08/15/stories/2004081501201300.htmhttp://www.reason.org/commentaries/kiesling_20030818b.shtmlhttp://www.reason.org/commentaries/kiesling_20030818b.shtmlhttp://www.claverton-energy.com/what-is-the-cost-per-kwh-of-bulk-transmission-national-grid-in-the-uk-note-this-excludes-distribution-costs.htmlhttp://www.claverton-energy.com/what-is-the-cost-per-kwh-of-bulk-transmission-national-grid-in-the-uk-note-this-excludes-distribution-costs.htmlhttp://www.visiongain.com/Report/626/The-Electric-Power-Transmission-and-Distribution-(T-D)-Equipment-Market-2011-2021http://www.visiongain.com/Report/626/The-Electric-Power-Transmission-and-Distribution-(T-D)-Equipment-Market-2011-2021http://en.wikipedia.org/wiki/International_Standard_Book_Numberhttp://en.wikipedia.org/wiki/Special:BookSources/0-87814-862-0http://www.who.int/mediacentre/factsheets/fs322/en/index.htmlhttp://en.wikipedia.org/wiki/World_Health_Organizationhttp://www.who.int/mediacentre/factsheets/fs322/en/index.htmlhttp://en.wikipedia.org/wiki/World_Health_Organizationhttp://en.wikipedia.org/wiki/World_Health_Organizationhttp://www.niehs.nih.gov/health/docs/emf-02.pdfhttp://en.wikipedia.org/wiki/National_Institute_of_Environmental_Health_Scienceshttp://en.wikipedia.org/wiki/National_Institute_of_Environmental_Health_Scienceshttp://www.oe.energy.gov/DocumentsandMedia/primer.pdfhttp://www.nytimes.com/2008/08/27/business/27grid.html?_r=2&ref=business&oref=sloginhttp://en.wikipedia.org/wiki/New_York_Timeshttp://www.supercables.com/Reference/tabsartikel.pdfhttp://www.newscientist.com/article/dn11907-superconducting-power-line-to-shore-up-new-york-grid.htmlhttp://www.futureenergies.com/print.php?sid=237http://news.bbc.co.uk/2/hi/technology/7990997.stmhttp://in.reuters.com/article/oilRpt/idINN0853911920090408http://www.geni.org/globalenergy/library/technical-articles/transmission/united-nations/center-for-science-and-technology-for-development/advanced-technology-assessment-system/energy-systems-environment-and-development.shtmlhttp://en.wikipedia.org/w/index.php?title=Electric_power_transmission&action=edit&section=29http://en.wikipedia.org/wiki/Special:BookSources/0849385784


17/20

Thomas P. Hughes,Networks of Power: Electrification in Western Society 1880-1930, The Johns Hopkins University Press,Baltimore 1983 ISBN 0-8018-2873-2, anexcellent overview of development during the first 50 years of commercial electric

power

Reilly, Helen (2008). Connecting the Country New Zealands National Grid 1886 -2007. Wellington: Steele Roberts. pp. 376 pages.. ISBN978-1-877448-40-9.

Westinghouse Electric Corporation, "Electric power transmission patents; Teslapolyphase system". (Transmission of power; polyphase system; Tesla patents)

Pansini, Anthony J, E.E., P.E. undergrounding electric lines. USA Hayden Book Co,1978. ISBN 0-8104-0827-9

[edit] External links

Look upgrid electricity in Wiktionary, the free dictionary.

Japan: World's First In-Grid High-Temperature Superconducting Power Cable System

A Power Grid for the Hydrogen Economy: Overview/A Continental SuperGrid

Global Energy Network Institute (GENI) - The GENI Initiative focuses on linkingrenewable energy resources around the world using international electricitytransmission.

Union for the Co-ordination of Transmission of Electricity (UCTE), the association oftransmission system operators in continental Europe, running one of the two largest

power transmission systems in the world

Non-Ionizing Radiation, Part 1: Static and Extremely Low-Frequency (ELF) Electric

and Magnetic Fields (2002) by theIARC-- Link Broken. A Simulation of the Power Grid - The Trustworthy Cyber Infrastructure for the Power

Grid (TCIP) group at the University of Illinois at Urbana-Champaignhas developedlessons and an applet which illustrate the transmission of electricity from generatorsto energy consumers, and allows the user to manipulate generation, consumption, and

power flow.

[hide]v d eElectricity generation

ConceptsAvailability factorBaseloadBlack startCapacity factorDemand factorDemand managementEROEIGrid storageIntermittencyLoad following

Peak demandRepoweringSpark spread

SourcesNonrenewableCoalFossil fuel power plantNatural gasPetroleum

NuclearOil shale

Renewable BiomassGeothermalHydroMarineSolarWind

TechnologyAC powerCogenerationCombined cycleCooling towerInductiongeneratorMicro CHPMicrogenerationRankine cycleThree-

phase_electric_powerVirtual power plant

DistributionDemand responseDistributed generationDynamic demandElectricitydistributionElectrical gridHigh-voltage direct currentLoad management
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Electric Transmission

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