Systems and methods of controlling uninterruptible power supplies of electrical power systems are described. According to one aspect, an electrical power system can include a generator having a stator and a rotor, a power converter coupled to a rotor bus of the rotor, and a control system comprising one or more control devices, the one or more control devices configured to operate the power converter to provide an AC signal for a rotor bus. The system can also include an uninterruptible power supply (UPS). The UPS can include a power storage element configured to receive and store electrical power, and configured to power the control system during a power failure, and, a health check circuit configured to verify a health status of the power storage element, and including a health check disable component configured to disable the health check circuit during the power failure.