Development of a Variable-Speed Generator Driven by an Internal CombustionEngine. Final Report, June 1989-December 1990

摘要

The report describes the development of a variable-speed generator driven by areciprocating engine. The operating speed range for the system is 1200 rpm to 3000 rpm. In that range the generator produces at its output 11 kW to 32 kW at high electrical efficiency. Less than 11 kW may be obtained by closing the throttle enough to produce the desired power level at 1200 rpm, but the more the throttle is closed the lower the electrical efficiency becomes. The engine-generator set uses a doubly-fed machine as the generator, a series-resonant converter to condition the power on the rotor windings, and a supervisory controller to execute the operating strategy and protection and diagnostics. It is a grid-connected system and can generate or consume reactive power on the stator windings of the generator. At synchronous speed the system is able to generate the same power as a fixed-speed system of the same rating. However, to reduce the output power it reduces the shaft speed instead of closing the throttle. The action maintains high electrical efficiency. The system is also able to operate above synchronous speed, which means it can produce more power than a fixed-speed system of the same rating.