The Power Grid ELEC 403 The Citadel Mark McKinney.

The Power GridThe Power Grid

ELEC 403The Citadel

Mark McKinney

The Power GridThe Power Grid

Number one invention of the 20th century is electrification

US has one of the most extensive and reliable networks in the world

The Power GridThe Power GridUS and Canada are

divided into eight large regions (RROs – Regional Reliability Organizations) overseen by the North American Electric Reliability Council (NERC)

South Carolina is in SERC Source: NERC

SERCSERCSERC Transmission Mileage

(161kV and above)

0

5,000

10,000

15,000

20,000

25,000

161kV 230kV 345kV 500kV0

200

400

600

800

1,000

1,200

1,400

1,600

1,800

161kV 230kV 345kV 500kV

2006-2010 2011 - 2015

Comprised of about 50 member companies, co-ops, and municipalities that supply energy within the region

Covers an area of approximately 560,000 square miles in sixteen states

Supplies about 1,000,000GWh of energy annually

Dominated (like the US) by coal and nuclear generation

Source: SERC Information Study, July 2006

SERCSERC Comprised of about 50

member companies, co-ops, and municipalities that supply energy within the region

Covers an area of approximately 560,000 square miles in sixteen states

Supplies about 1,000,000GWh of energy annually

Dominated (like the US) by coal and nuclear generation

Nuclear16%

Dual Fuel (Gas/Oil)12%

Gas14% Oil

2%

Net Internal Purchases

9%

Coal38%

Pumped Storage3%

Hydro6%

Source: SERC Information Study, July 2006

US Energy UsageUS Energy Usage

Source: US Energy Information Administration

http://www.eia.doe.gov/emeu/aer/pecss_diagram.html

Power in SCPower in SC South Carolina’s four nuclear power

plants supply about half of the State’s electricity demand.

South Carolina receives most of its coal from Kentucky.

Industry is the State’s largest energy-consuming sector, accounting for roughly two-fifths of total energy consumption.


http://tonto.eia.doe.gov/state/state_energy_profiles.cfm?sid=SC

Power in SCPower in SC If licensing and construction go as

planned, two new nuclear reactors could come online in South Carolina by 2016.

Per capita electricity use in South Carolina is higher than the nationwide average due to high air-conditioning demand during hot summer months and the widespread use of electricity for home heating during generally mild winter months.


http://www.eia.gov/cneaf/nuclear/state_profiles/south_carolina/sc.html

The US Power SystemThe US Power SystemThe Generating Station

• Can be nuclear, coal, etc…

• Usually a steam turbine

• Generates 3-phase AC power

• Output usually in the 10-30kV range

• Voltage must be increased to high voltage for “transmission”

The US Power SystemThe US Power SystemThe Transmission Substation

• Voltage stepped-up to 150-500kV

• Allows for transmissions up to 300 miles.

The US Power SystemThe US Power SystemTransmission Lines

• The transmission phase covers long distances at high voltages

• Towers are BIG

• Overseen by NERC

• Connect power plant to localities

• Also connect the various companies and even regions

Transmission LinesTransmission LinesAluminum has replaced copper lines because they have lower cost and are lighter weight.

A shield wire is connected directly to the top of transmission line towers to protect the main conductors from a direct lightning strike.

Transmission lines are connected to the towers by porcelain insulators.

Source: American Transmission Company

Transmission Line Structures


Electrical Properties Electrical Capacity (I) Transmission Distance (V) Efficiency (R, L, & C)

Aesthetics Wood or Steel Construction Physical Size

Environmental Impact

Designs of transmission lines vary greatly to meet various needs



Accessibility Constructability Maintainability

Zoning and land-useRight-of-way/Easement

Width and height restrictions Determine voltage

and height of tower

Designs of transmission lines vary greatly to meet various needs



Double-circuit, 138-kilovolt transmission line built on wood structures.

Local electric distribution lines, cable and telephone lines are sometimes carried on the same structures to make efficient use of space. Taller poles are needed to do this.




Double-circuit, 138-kilovolt line build on galvanized steel poles.

This type of design is often used when the line will carry heavy electric loads. Higher voltage lines require taller poles-sometime 100 feet or more.




138-kilovolt single-circuit line on weathering steel.

This type of maintenance-free structure will weather (rust) over time to give the appearance of wood and is generally used in wooded areas.




H-frame wood structure. This type of design allows for shorter spans (the distance between structures.) In general the height of the structures is less than single pole structures.




138-kilovolt steel H-frame. Require less height, but wider right-of way.




345-kilovolt, double-circuit on single poles.

Higher voltage lines require taller poles and wider rights-of-way.


The Power SubstationThe Power SubstationPower Substation

• Steps-down the HV for the “distribution” network

• Voltages <100kV

The Power SubstationThe Power SubstationPower Substation

Switch Tower and Main Transformer

Distribution Bus

The Distribution NetworkThe Distribution Network

Smaller, low-voltage poles

Simpler designs – usually wooden Ts

Typically 7.2kV

What’s on the poles?What’s on the poles?

Capacitor banks


Reclosers


Transformers

At your houseAt your house

TransformerTap off of one

(occasionally two) phase

The Power Grid ELEC 403 The Citadel Mark McKinney.

Documents

Transcript of The Power Grid ELEC 403 The Citadel Mark McKinney.