Determination of Generator Stand-by Reserve Requirements

During the past few years there has been a trend toward the use of statistics of forced (unscheduled) generator outages as a basis for calculating the proper amount of stand-by reserve generation for a given power system. This paper presents a method of analysis which was developed to fit the needs of a system having a large number of generators, but which, it is believed, can be used to advantage for small systems also. The method is based partially on previously published results.^1,2,3 This method lends itself readily to calculations, involves few approximations, and has sufficient flexibility to take account of several types of machines having different outage factors. Although the discussion is confined to generator outages, the method of analysis here presented may be used for calculation of simultaneous overlap of events of other types for which corresponding assumptions can be made. Examples are random outages of transmission lines and other types of equipment, random use of parallel communication channels, and supply of current to a number of items of equipment, each having a random duty cycle. The method is applicable to any situation which can be represented on a graph similar to Figure 1(A), provided that necessary statistical data are available.