The electricity generation, transmission, distribution and control networks make up the electrical grid. The simplest grids link a local generator to homes, but grids can cover whole continents too. Smaller grids have a radial structure with supply lines branching out from a large centralised
electricity supplier. This is relatively simple to operate, but if a line goes down, users are cut off.
To ensure reliable supply, most grids use a mesh structure. In this configuration, the power lines of any given electricity supply source are interconnected with those of other sources. If one line has a problem, power can be rerouted from elsewhere while the damaged line is repaired.
To plan, operate and manage large interlinked systems, we need control centres where operators monitor grid status. They will adjust to electrical demand variations in real time, using sophisticated network management systems.
The AC electrical grids are composed of substations connected to each other by overhead, underground, or even submarine lines.
To plan, operate and manage large interlinked systems, we need control centres where operators monitor grid status. They will adjust to electrical demand variations in real time, using sophisticated network management systems.
In connecting larger networks across countries or continents, we are facing a challenge: directly connecting AC grids with different frequencies is not possible. DC is the answer. We therefore convert AC into DC to enable the interconnection.
Did you know? In order to reduce losses, the electricity generated by the power station (in the range of 10-20 kV) is first stepped up to 230 kV or 400 kV in Europe, 500 kV in the Americas (except Canada where up to 765 kV is used) and as high as 1,100 kV in China. It is then transmitted by high voltage transmission grids at powers of up to 800 kV. From the grid, the electricity is converted by transformers in the distribution network, stepping the power down to medium voltages (below 50 kV) and finally to the voltage used by consumers (220-240 V in Europe or 110 V in North America).