Thermally Integrated Induction Generator for Adjustable Speed Reciprocating Cogeneration Systems

The distributed generation based on the micro- cogeneration (less than 1 MW) is an emerging technology in the electric energy production scenario. Among the prime mover technologies the reciprocating engine is still the most widespread, due its distinctive features and the possibility to benefit of important synergy with traction applications. Concerning the cogenerator electric parts, the state of the art is based on an electric three-phase generator directly connected to the grid; hence the engine must deliver the requested power at the fixed speed determined by the frequency of the grid. Some potential advantages can be exploited adopting the electronic power control for the load following with the engine speed regulation. The paper discusses the design of a 125 kVA induction generator to be thermally integrated with the reciprocating engine in an adjustable speed cogeneration system: the single liquid cooling circuit simplify the cogeneration system and allows the recuperation of the iron and copper losses.