Emergency strategy operation optimization for atmosphere environment control system in space station

Environment control system (ECS) in a space station is an essential system for the astronaut life safety. Composed of a number of coupling subsystems, the ECS functions as the controller of the cabin air condition and the environmental parameters, which are essential parts to the astronauts' life safety. As its subsystems are power-consuming, the system's regular operation highly relies on the stability of the power supply system and the ECS should have the ability to reconfigure operation strategy in some emergency conditions. In this paper, the emergency strategy optimization method of ECS is studied under potential insufficient power supply condition. To study this issue, we establish basic ECS mathematical models involving its substances, energy as well as consumption, and the non-regenerative substance lifetime conception, which represents the remaining amount of non-regenerative life support substance. A multi-objective optimization method is developed to search the ECS emergency strategy. The maximum non-regenerative substance lifetime and the minimum power consumption are chosen as the optimization objective functions. Some adjustable key variables are chosen as the optimal variables, which represent the way to reconfigure the operation strategy. With the constraints of 5 main environmental parameters, the non-dominated sorting genetic algorithm-Ⅱ (NSGA-Ⅱ) is adopted to obtain the Pareto optimal solution set and the Pareto optimal frontier (POF). The results of optimization research show that the presented optimal method can obtain the optimal emergency electric energy allocation strategy for subsystems under different insufficient power supply conditions, and the optimal reconfigured operation strategy can meet the maximum system lifetime and minimum system supply energy requirement.