Load-following power timeline analyses for the International Space Station

Spacecraft are typically complex assemblies of interconnected systems and components that have highly time-varying thermal, communications and power requirements. It is essential that power systems designers be able to assess the capability of the spacecraft to meet these requirements which should represent a realistic projection of demand for these resources once the vehicle is on-orbit. To accomplish the assessment from the power standpoint, a computer code called ECAPS has been developed at NASA Lewis Research Center that performs a load-driven analysis of a spacecraft power system given time-varying distributed loading and other mission data. This program is uniquely capable of synthesizing all of the changing spacecraft conditions into a single, seamless analysis for a complete mission. This paper presents example power load timelines with which numerous data are integrated to provide a realistic assessment of the load-following capabilities of the station´s PV power system. Results of analyses show how well the power system can meet the time-varying power resource demand