Transmission And Distribution Of Electrical Power Pdf

[Manases Yatnalkar]

Conventionalpower grids

Which produce electricity in large quantities and deliver it in a one-way direction to different users, increasingly have to integrate excess power generated locally, for example via solar panels on a house. To ensure that the grid can safely absorb such bi-directional distributed energy resources (DERs), it must add intelligence

They concern overhead lines, cables, electrical conductors, insulators, power transformers, etc.. These standards also help utilities to roll out energy-efficient technologies, from high-efficiency transformers to more energy-efficient conductors. Others paved the way for the digitalization and automatization of the electrical grid.

All of these standards serve as the basis for testing and certification of components, devices, and systems. IEC runs four Conformity Assessment Systems which verify whether a product or device is built to the requirements contained in IEC Standards.

Electricity is generated at power plants and moves through a complex system, sometimes called the grid. The grid includes electricity substations, transformers, and power lines that connect electricity producers and consumers. Most local grids are interconnected to maintain reliability and for commercial purposes, forming larger, more dependable networks that helps suppliers consistently produce the right amount of electricity to meet demand.

In the United States, the entire electricity grid consists thousands of miles of high-voltage power lines and millions of miles of low-voltage power lines. This network of power lines connects thousands of power plants to hundreds of millions of electricity customers across the country.

The origin of the electricity that consumers purchase varies. Some electric utilities generate all the electricity they sell using just the power plants they own. Other utilities purchase electricity from other utilities, power marketers, and independent power producers or from a wholesale market organized by a regional transmission reliability organization.

The retail structure of the electricity industry varies from region to region. The company selling you power may be:A not-for-profit municipal electric utilityAn electric cooperative owned by its membersA private, for-profit electric utility owned by stockholders (often called an investor-owned utility)

Power plants generate the electricity that is delivered to customers through transmission and distribution power lines. High-voltage transmission lines, such as those that hang between tall metal towers, carry electricity over long distances. Higher voltage electricity is more efficient and less expensive for long-distance electricity transmission. Lower voltage electricity is safer for use in homes and businesses. Transformers at substations increase (step up) or reduce (step down) voltages to adjust to the different stages of the journey from the power plant on long-distance transmission lines to distribution lines that carry electricity to homes and businesses.

At the beginning of the 20th century, more than 4,000 electric utilities operated in isolation from each other. As the demand for electricity grew, especially after World War II, utilities began to connect their transmission systems. These connections allowed utilities to share the economic benefits of building large and often jointly owned power plants to serve their combined electricity demand at the lowest possible cost. Interconnection also reduced the amount of extra generating capacity that each utility had to hold to ensure reliable service during times of high and peak demand. Over time, three large, interconnected systems evolved in the United States.

The stability of the electricity grid requires electricity supply to constantly meet electricity demand, which in turn, requires numerous entities that operate different components of the grid to coordinate with each other. Local electricity grids are interconnected to form larger networks to maintain reliability and for commercial purposes. At the highest level, the U.S. power system in the Lower 48 states is made up of three main interconnections, which operate largely independently from each other with limited transfers of electricity between them:

The Eastern and Western Interconnections in the United States are also linked with Canada's power grid. The network structure of the interconnections helps maintain the reliability of the grid by providing multiple routes for power to flow and allowing generators to supply electricity to many load centers. This redundancy helps prevent transmission line or power plant failures from causing interruptions in service to retail customers.

The three major grid interconnections describe the large-scale physical structure of the grid. The regional operation of the electric system is managed by entities called balancing authorities. They ensure that electricity supply constantly matches power demand. Most of the balancing authorities are electric utilities that have taken on the balancing responsibilities for a specific part of the power system. All of the regional transmission organizations in the United States also function as balancing authorities. ERCOT is unique because the balancing authority, interconnection, and regional transmission organization are all the same entity and physical system.

A balancing authority ensures that electricity demand and supply are finely balanced to ensure the grid is safe and reliable. If electricity demand and supply fall out of balance, local or even widespread blackouts can result. Balancing authorities maintain appropriate operating conditions for the electric system by ensuring that enough electricity is available to serve expected demand, which includes managing electricity transfers with other balancing authorities.

Electric utilities are responsible for maintaining the safety of their systems and planning for the future power needs of their customers. Initially, the electric power industry developed voluntary standards to ensure they coordinated with linked interconnections. Today, mandatory reliability standards for planning and operating power systems and for addressing security concerns at critical electrical infrastructure are in place. The North American Electric Reliability Corporation developed and enforces mandatory grid reliability standards approved by the Federal Energy Regulatory Commission (FERC). In Canada, Canadian regulators fill this role.

Construction of electricity infrastructure in the United States began in the early 1900s and investment was driven by new transmission technologies, central-station generating plants, and growing electricity demand, especially after World War II. Now, some of the older, existing transmission and distribution lines have reached the end of their useful lives and must be replaced or upgraded. New power lines are also needed to maintain the electrical system's overall reliability and to provide links to new renewable energy generation resources, such as wind and solar power, which are often located far from where electricity demand is concentrated.

The transmission network is like the motorways, carrying vehicles (electricity) at high speed (high voltage) across the country. This is the network of big pylons and overhead lines you see around the country.

The distribution networks are the local roads, connecting motorways with communities to help vehicles complete their journey. These are the smaller pylons (and underground cables) carrying lower voltage lines.

Electric power transmission is the bulk movement of electrical energy from a generating site, such as a power plant, to an electrical substation. The interconnected lines that facilitate this movement form a transmission network. This is distinct from the local wiring between high-voltage substations and customers, which is typically referred to as electric power distribution. The combined transmission and distribution network is part of electricity delivery, known as the electrical grid.

Efficient long-distance transmission of electric power requires high voltages. This reduces the losses produced by strong currents. Transmission lines use either alternating current (AC) or direct current (DC). The voltage level is changed with transformers. The voltage is stepped up for transmission, then reduced for local distribution.

A wide area synchronous grid, known as an interconnection in North America, directly connects generators delivering AC power with the same relative frequency to many consumers. North America has four major interconnections: Western, Eastern, Quebec and Texas. One grid connects most of continental Europe.

Historically, transmission and distribution lines were often owned by the same company, but starting in the 1990s, many countries liberalized the regulation of the electricity market in ways that led to separate companies handling transmission and distribution.[2]

Most North American transmission lines are high-voltage three-phase AC, although single phase AC is sometimes used in railway electrification systems. DC technology is used for greater efficiency over longer distances, typically hundreds of miles. High-voltage direct current (HVDC) technology is also used in submarine power cables (typically longer than 30 miles (50 km)), and in the interchange of power between grids that are not mutually synchronized. HVDC links stabilize power distribution networks where sudden new loads, or blackouts, in one part of a network might otherwise result in synchronization problems and cascading failures.

Electricity is transmitted at high voltages to reduce the energy loss due to resistance that occurs over long distances. Power is usually transmitted through overhead power lines. Underground power transmission has a significantly higher installation cost and greater operational limitations, but lowers maintenance costs. Underground transmission is more common in urban areas or environmentally sensitive locations.

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