G&Ts operate these lines, which carry the electric energy from the generating stations to the places where electricity is used. Transformers at the generating plant increase the voltage up to a transmission voltage (69 kV, 115 kV, 230 kV, 500 kV, 765 kV), so it can travel long distances over high-voltage transmission lines. Wind hydro and solar are other forms of energy producers. In a combustion turbine, the fuel (gas or oil) is burned and the hot gas drives a turbine. At a steam generating plant, the fuel (coal, nuclear or biomass) heats water to make steam and drive a turbine. Generation and transmission cooperatives (G&Ts), like Great River Energy, operate power generating facilities. Transmission Nominal Voltage: +/- 400 kV HVDC Structures are generally single pole towers, constructed of either wood or steel and range from 50-70 feet tall. Many smaller and rural industrial customers receive power directly from these systems. These also provide connection to some of the more remote and sparsely populated areas in greater Minnesota. Some large industrial customers may be served directly from 161-kV and 115-kV systems.ġ61-kV and 115-kV structures are generally single pole structures between 70 and 95 feet tall.Ħ9-kV through 23-kV systems transmit power to distribution substations. (photos below of each).ġ61-kV and 115-kV systems are responsible for transmitting power from the larger transmission system and generation facility throughout the entire state. Structures are generally steel lattice towers, wooden H-Frames or single-pole steel. There are also two direct current (DC) lines, one of 400-kV and one at 500-kV. High-voltage (230-kV, 345-kV, 400-kV (DC), 500-kV (DC):Ĭurrently in Minnesota, the high-voltage system is generally comprised of 230-kiloVolt and 345-kV systems.The type of transmission structures used for any project is determined by the characteristics of the transmission line’s route, including terrain and existing infrastructure. Distribution lines carry power to farms, homes and businesses. At numerous substations on the transmission system, transformers step down the power to a lower voltage and deliver it to distribution lines. At a generating plant, electric power is “stepped up” to several thousand volts by a transformer and delivered to the transmission line. Transmission lines are sets of wires, called conductors, that carry electric power from generating plants to the substations that deliver power to customers. Transmission 101: the basics of how the system works

Substation design 101