Electric power distribution
Commercial and residential customers are connected to the secondary distribution lines through service drops.
By contrast, direct-current indoor incandescent lighting systems, such as Edison's first power station, installed in 1882, had difficulty supplying customers more than a mile away because they used a low voltage (110 V) from generation to end use.
The low voltage translated to higher current and required thick copper cables for transmission.
In practice, Edison's DC generating plants needed to be within about 1.5 miles (2.4 km) of the farthest customer to avoid even thicker and more expensive conductors.
AC became the dominant form of transmission of power with innovations in Europe and the US in electric motor designs, and the development of engineered universal systems allowing the large number of legacy systems to be connected to large AC grids.
[6][7] In the first half of the 20th century, in many places the electric power industry was vertically integrated, meaning that one company did generation, transmission, distribution, metering and billing.
Starting in the 1970s and 1980s, nations began the process of deregulation and privatization, leading to electricity markets.
Electric power begins at a generating station, where the potential difference can be as high as 33,000 volts.
Users of large amounts of DC power such as some railway electrification systems, telephone exchanges and industrial processes such as aluminium smelting use rectifiers to derive DC from the public AC supply, or may have their own generation systems.
High-voltage DC can be advantageous for isolating alternating-current systems or controlling the quantity of electricity transmitted.
Since 1975, when Merlin and Back[11] introduced the idea of distribution system reconfiguration for active power loss reduction, until nowadays, a lot of researchers have proposed diverse methods and algorithms to solve the reconfiguration problem as a single objective problem.
Some authors have proposed Pareto optimality based approaches (including active power losses and reliability indices as objectives).
For this purpose, different artificial intelligence based methods have been used: microgenetic,[12] branch exchange,[13] particle swarm optimization[14] and non-dominated sorting genetic algorithm.
It uses higher voltages (than urban distribution), which in turn permits use of galvanized steel wire.
In New Zealand, Australia, Saskatchewan, Canada, and South Africa, Single-wire earth return systems (SWER) are used to electrify remote rural areas.
In North America, overhead distribution systems may be three phase, four wire, with a neutral conductor.
Most of the world uses 50 Hz 220 or 230 V single phase, or 400 V three-phase for residential and light industrial services.
Single-phase distribution, with one live wire and the neutral is used domestically where total loads are light.
In the UK a typical urban or suburban low-voltage substation would normally be rated between 150 kVA and 1 MVA and supply a whole neighbourhood of a few hundred houses.
Most of the Americas use 60 Hz AC, the 120/240 volt split-phase system domestically and three phase for larger installations.
[20] There are four high-voltage direct current (HVDC) converter stations that move power across Japan's AC frequency border.
The 240 volt circuits are typically used for appliances requiring high watt heat output such as ovens and heaters.
