Optimal Scheduling of Rover Charging for Lunar Power Systems

Extra-vehicular activities (EVAs) using pressurized and unpressurized rovers are planned by different space agencies to explore the lunar surface. The battery-powered lunar rovers can be charged from the lunar power systems, called lunar<br/>microgrids (MGs). These MGs are required to maintain reliable operations even in harsh and resource-scarce environments like space, fulfilling the mission’s long- and short-term goals, considering the power and resource availability, power demand, and system constraints. Preparing for an upcoming EVA demands intelligent strategies for planning the MG’s operation for autonomous power control (APC), energy management systems (EMS), and charging of rovers. The optimal operation of MGs can be affected by arbitrarily charging the rovers, altering the MG’s planned resource availability, and compromising the mission’s safety and reliability. This paper proposes an optimization framework to charge the lunar rovers optimally, considering the desired period of EVA and MG’s operational requirements. This defines well-designed operating references for MG’s APC and EMS. To investigate the performance of the proposed scheduling framework, two case studies are considered. In the first case, the paper considers the habitat MG to be supplied from its own PV-battery MG, to which the rover is also connected. The power demand profile of the habitat MG is modeled considering several activities in the habitat and wastewater filtration process. It can be observed that the optimization framework schedules the rover’s optimal charging duration and power from the excess PV power that would otherwise have been shed. In the second case, a multi-microgrid (MMG) system consisting of the habitat and in-situ resource utilization (ISRU) MGs is considered with power transmission among them, and it is assumed that the rover is charged from the habitat MG. The ISRU MG is also considered to be supplied from its PV-battery MG to supply its power demand for producing life-supporting resources according to the needs of the habitat. It is observed that the excess PV power from the ISRU MG is transmitted to charge the rover and maintain the battery state-of-charge (SoC) at the desired level.