Patent attributes
An uninterruptible power supply (UPS) of a UPS system including a plurality of UPSs connected in parallel at a load bus and configured to provide power thereto from respective batteries of a plurality of batteries is operated such that a difference between a variable, for example, battery voltage, indicative of battery capacity for a battery associated with the subject UPS and an average value of the variable for the plurality of batteries is determined and a power flow between the subject UPS and the load bus is controlled responsive to the determined difference. Controlling a power flow between the subject UPS and the load bus responsive to the determined difference may include, for example, controlling a phase of an inverter of the subject UPS responsive to the determined difference.