Off-nominal conditions and caution and warning techniques for the electric power system for the International Space Station

In this paper the latest electric power system (EPS) off-nominal operations and caution and warning techniques for the International Space Station (ISS) are presented. The EPS off-nominal operations development consists of a compilation of analyses that provide plans and procedures for continued operation of the EPS in the event of a failure or anomaly. The off-nominal conditions encompass the following: (1) expected system performance changes (i.e., contributions due to aging); (2) failures that are automatically detected, isolated, and reconfigured; (3) failures that are manually reconfigured (extravehicular activity or via command and control by an operator); and (4) unexpected system anomalies. Off-nominal scenarios including those associated with failure detection, isolation and recovery (FDIR) operations within the ISS EPS are performed by FDIR functionality allocated to individual FDIR domains resident in equipment that implements the EPS functionality