Electric power is generated and ‘shipped’ to consumers across a system know as an energy grid. The grid is a network of transmission lines connecting power generators to consumers. The grid is used to transport electric power (megawatts or megavolt-amperes) over transmission lines.
Electricity generation and consumption must be balanced across the entire grid or a region or country because energy is consumed as it is produced. A failure in one part of the grid can cause current to re-route itself to flow from the remaining generators to consumers over transmission lines of that may not have that capacity. This re-routing and “flooding” of power to another part of a grid will cause further failures. When this happens from one part of the grid going down, then knocking down another part of the grid it’s called a cascading failure.
The North American Electric Reliability Corporation was formed in 2006 to coordinate power grid developments and develop protocols to maintain a stable grid. Because of the interconnected energy grids across North America NARC has advisory powers in parts of Canada and Mexico. In Europe this is done by the European Network of Transmission System Operators for Electricity.
The cheapest and simplest topology for a transmission grid is a tree shape where power from a large supply, like a generating station, radiates out into progressively lower voltage lines until the destination homes and businesses are reached. Historically this was the first type of energy grid deployed. Now transmission grids require greater reliability which can be provided by mesh networks. Mesh networks include many redundant connections in networks that provide for failure. If one link is severed the entire grid will not collapse. Mesh grids use more wiring, more connections and are more expensive. Mesh networks are most often deployed in transmission grids between primary power sources.
Electrical systems found in Europe and parts of Asia are called looped grids. These systems are designed to provide more even power distribution and some redundancy.