Comparison between different procedures of reliability analysis for emergency and stand-by power systems

A general purpose Emergency Generator Set (EGS) is considered for a methodological study and related reliability behaviour is analyzed. In particular in a procedure of reliability and availability analysis of a EGS, dependent failure events need a complex mathematical model as “state-space model” to be a accurately evaluated. Furthermore these dependent failure events are one of the most important reliability characteristic of EGS. This paper suggests a procedure for reliability calculations in presence of dependent failure based on the evaluation of a equivalent failure rate that can be fitted to a network reduction method by simple mathematical calculations. The simplified models analyzed show a good accuracy for a wide range of variation of main reliability characteristics of EGS and utility. The advantages obtained are very useful on reliability evaluation because the possibility of use of network approach provides a shorter route to calculation and it is applicable by a larger number of power system designers.