ISOLATED PARALLEL UPS SYSTEM WITH FAULT LOCATION DETECTION

An uninterruptible power supply (UPS) system (100, 300) is provided. The UPS system includes a plurality of UPSs (102, 104, 106, 302, 304, 306), a ring bus (118, 314, 410, 510) that electrically couples the UPSs (118, 314, 410, 510) together, a static switch (340, 342, 344) coupled between an associated UPS of the UPSs (118, 314, 410, 510) and the ring bus (118, 314, 410, 510), and a controller (200). The controller (200) receives current data representative of an inverter current and a load current associated with the associated UPS. An output capacitor (606) of the associated UPS is coupled to a node that conducts the inverter current and the load current. The controller (200) further calculates a measured current based on the received current data, determines a voltage of said output capacitor (606), generates a derived current based on the determined voltage and a predetermined capacitance of said output capacitor (606), compares the measured current and the derived current to identify a fault location, and controls said static switch (340, 342, 344, 408) based on the identified fault location.