Reliability comparison of substation designs

This paper introduces the concept of reliability evaluation of substation designs in terms of the cost of lost load. To overcome the problem of dimensionality, the failure states are merged and a linear-programming approach is used to determine the LOLE by means of state-enumeration techniques. Where the single-line diagram of the substation is not symmetrical, an equivalent is constructed, thus giving rise to higher and lower values of LOLE, in other words defining an unreliability region. The average value of LOLE, called the mean evaluation of lost load (MELL), can then serve as an input to the economic comparison of alternative substation configurations.