Abstract: This paper mainly studies the seriously harmful short-circuit fault of satellite power system and analyzes the transient characteristics based on both circuit model and mathematical model. The transient process can be subdivided into four stages: the bus capacitor discharge stage, the solar array regulator power up stage, the battery discharge regulator power up stage and the battery diode conduction stage. This paper points out the conversion conditions of these stages. According to the faults transient process, this paper analyzes the requirements and impacts of the static voltage drop. Then the influences of fusing I 2T, short circuit resistance, battery internal resistance and battery open circuit voltage are determined considering that the fuse protection is popular in satellites. Finally, this paper proposes a new grounding mode and parameter optimization methods including the battery open circuit voltage, the short circuit resistance and the threshold of under voltage protection, which can make the critical stand alone equipment keep working during the fault process.

Key words: Satellite power system, Fault analysis, Bus voltage drop, Influencing factors, Protection