Two-interdependent-performance multi-state system: Definitions and reliability evaluation

摘要

Many engineering systems are designed to complete two tasks simultaneously and therefore need to consider two interdependent performance measures. For example, a combined heat and power (CHP) system requires two interdependent performance variables of heat power and electric power to measure its reliability. The operation of such a two-interdependent-performance multi-state system (TIP-MSS) is usually constrained by a two-dimension feasible operating region (FOR) specific to the state. Hence, the performance rate of the TIP-MSS system in each state should be represented by the upper boundary of the FOR corresponding to the concept of "capacity" in the single-performance MSS model. Considering the interdependence between the performance variables, the concept and definitions of the TIP-MSS are proposed. An object, i.e., the performance trade-off curve, is utilized to represent the performance rates. The universal generating function (UGF) method is extended to represent the performance distribution of a TIP-MSS. Moreover, different composition operators are defined for analyzing the reliability of TIP-MSS with parallel/series structures. The availability criterion based on the TIP-UGF method is also proposed. Finally, the proposed models and methods are illustrated by two numerical examples.