Standby Electric Power Plant

a power plant in which part or all of the units operate when the consumption of electric power in the system sharply increases for short periods of time—that is, at times of peak load. The units must have a high degree of operational adjustability and must be capable of building up full power rapidly—sometimes in 2–3 minutes—and of being shut down just as rapidly. Standby power plants can be of the hydroelectric or the gas-turbine type; steam turbine electric power plants that have been adapted for such operation can also be used as standby plants.

The use of storage-type standby electric power plants is advantageous. Such plants can store energy at nighttime, when power consumption is low, and thereby create a load for the base-load steam-turbine power plants. In daytime, the stored energy is used to cover peak loads. Such standby electric power plants are exemplified by pumped-storage hydroelectric power plants and by certain gas-turbine plants. In the latter, air is pumped and compressed during the night and is stored in airtight spaces, for example, in underground chambers. In the future, operating hydroelectric power plants will function increasingly often as standby power plants. In the USSR, a second hydroelectric power plant with a capacity of 828 megawatts was put into operation at Dneproges in 1975. This plant will supply standby power for the power system of the southern USSR.

Figure 1. The covering of peaks and equalization of power-system load upon the connection of a gas-turbine unit (a), a pumped-storage hydroelectric unit (b), and a gas-turbine unit with air storage (c): (N_n) standby power, (P_non) nonuniformity of load during 24 hours. Time of day in hours is plotted along the abscissa axis, and power-system load in relative units along the ordinate axis.

Modern standby electric power plants also function as reserve power plants. Such plants are automated and are operated by remote control from a central station. The graphs in Figure 1 show the smoothing effect in the operating conditions of base-load electric power plants (mostly of the thermal type) as a result of the introduction of various types of standby electric power plants into the power system.