电力工业发展初期，电能是直接在用户附近的发电站(或称发电厂)中生产的，各发电站孤立运行。随着工农业生产和城市的发展，电能的需要量迅速增加，而热能资源(如煤田)和水能资源丰富的地区又往往远离用电比较集中的城市和工矿区，为了解决这个矛盾，就需要在动力资源丰富的地区建立大型发电站，然后将电能远距离输送给-The early days of electric power industry, electricity is directly in the user in the vicinity of the station (or power plant) in production, the power plant to run in isolation. As the industrial and agricultural production and urban development, rapid increase in electricity requirements, while the thermal energy resources (such as coal), and water resource-rich areas are often far away from power are concentrated in urban and industrial and mining areas, in order to solve this contradiction, we need to resource-rich regions in the power to establish large-scale power plants, and then long-distance power transmission to the