Patent ID: 11923721
Assignee: SAUDI ARABIAN OIL COMPANY
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC H | IPC H

Claim 0:
1. A system comprising:
an alternating current (AC) input connected to an output bus of the system;
a plurality of battery cells connected in series;
a first connection path from an intermediate battery cell of the plurality of battery cells to the output bus of the system, wherein a subset of the plurality of battery cells includes a first battery cell through the intermediate battery cell;
a second connection path from a last one of the plurality of battery cells to an output bus;
a circuit switch installed along the second connection path, the circuit switch configured to open or close the second connection path; and
an undervoltage relay in the output bus, wherein the undervoltage relay is set at a threshold voltage that is less than a voltage of the first battery cell through the intermediate battery cell of the subset of the plurality of battery cells when the AC input fails, and wherein the undervoltage relay is configured to:
in a first mode of operation, control the circuit switch to open the second connection path when the voltage on the output bus exceeds the threshold voltage so that the subset of the plurality of battery cells provides power to the output bus; and
in a second mode of operation, control the circuit switch to close the second connection path when the voltage on the output bus drops below the threshold voltage so that all of the plurality of battery cells provide power to the output bus.