Electricity is an energy source powered by electricity. Discovered in the 1870s, the discovery and application of electricity set off the second industrial climax. It has become one of the three scientific and technological revolutions in the world since the 18th century in human history. Since then, science and technology has changed people's lives. 

 The large-scale power system in the 20th century is one of the most important achievements in the history of human engineering science. It is a power production and consumption system composed of power generation, transmission, power transformation, power distribution and electricity consumption. It converts the primary energy of nature into electricity through mechanical energy devices, and then supplies electricity to users through power transmission, transformation and distribution.