Reliability analysis and optimal redundancy for a satellite power supply system based on a new dynamic k-out-of-n: G model

As an important system in satellites or space stations, a power supply system (PSS) is used to support the work of various electrical devices via power supply channels. A PSS fails once the number of undamaged channels is smaller than the number of devices that currently require power supply. A channel may fail only when it powers a device. To describe these characteristics of PSSs, a new dynamic k-out-of -n: G model is developed in this work by considering the following dynamic mechanisms. First, the failure threshold k is assumed to be a random process rather than a fixed value. Second, the decline rate of the number of undamaged channels is dynamic and depends on k. For the new model, a closed-form solution of reliability is derived under the assumption that the channel lifetime follows an exponential distribution. For other cases, a simulation method is employed to evaluate the lifetime of the system. Based on the evaluation of reliability, the optimal redundancy of channels is proposed by minimizing the weight of a PSS under a constraint of reliability.