Carrier Channels for Telemetering

This paper describes design engineering considerations involved in the application of 68 carrier current terminals at 25 locations used to establish the major portion of a 6,500-mile telemeter and automatic load-frequency control system. Both telephone-line and power-line carrier equipment is used with the latter predominating and consisting of four general types: keyed continuous wave; multitone amplitude modulation; multitone frequency modulation; and frequency shift. The quantity and direction of power flowing in 17 major transmission tie lines between the Tennessee Valley Authority (TVA) and surrounding power systems are telemetered an average distance of 172 miles to an operating office where tie-line loadings are totalized. Based on this net interchange quantity, deviation. from-schedule control signals, on a time-duration impulse basis representing kilowatts, are sent by a frequency-shift powerline carrier system to a total of 12 hydroelectric plants, to automatically regulate the governors of generators in response to load and frequency changes on the tie lines within the limits set by scheduled water releases which are co-ordinated with other objectives of the TVA. Two separate master control carrier channels are used with one serving seven and the other eight hydroelectric generating plants. To provide operating flexibility, three hydro plants are common to both carrier control channels.