US Patent 7078825 Microturbine engine system having stand-alone and grid-parallel operating modes

A microturbine engine that includes a compressor that is operable to provide a flow of compressed air. The compressed air flows through a recuperator where it is preheated before delivery to a combustor. The preheated compressed air mixes with a fuel and is combusted within the combustor to provide a flow of products of combustion. The flow of products of combustion pass through one or more turbines to drive the compressor and a synchronous generator. The synchronous generator is able to synchronize to a priority load, to the utility grid or to both depending on the mode of operation. A control system monitors various engine parameters as well as load and grid parameters to determine the desired mode of operation.