Uninterruptible electric power supply

Abstract

An electric power supply system for a load wherein two prime movers, a gas turbine and a synchronous electric motor receiving its motive energy from a source of electric power, such as a public utility, are utilized to simultaneously drive an electric generator. A fuel controller, which is responsive to the output of the generator, operates in an isochronous mode and regulates the supply of fuel to the gas turbine from a fuel source to bring the turbine, generator, and motor up to operating speed. A paralleling controller, which is responsive to both the output of the generator and the output of the utility power source connects the motor to the utility when the outputs of the generator and utility are of equal frequency and phase so that the motor shares the load in driving the generator. A power sensor compares the flow of electric energy to the motor with a fixed reference signal, and generates a resultant difference signal which is used to trim the turbine fuel controller to speed up or slow down the turbine so that constant power flows through the power sensor and motor, resulting in the motor always providing a fixed or predetermined amount of driving force to the generator while the turbine provides the rest. Additionally provided is a reverse current sensor, which detects interruption of current flow from the utility, and immediately disconnects the motor from the utility. The fuel controller now operates in an isochronous mode without trimming signals from the power sensor, and the turbine is thus controlled to provide all the needed driving force to drive the generator to maintain constant generator frequency and phase output. An overrunning clutch is utilized between the turbine and generator which allows easy disconnection of the turbine from the generator in the event the turbine becomes disabled, while all the driving force needed by the generator is supplied by the synchronous motor. In the event the entire electric system is disabled, a switch connects the load directly to the utility source.

Dependencies are inferred from the claim text.