Abstract: An electrical power generating arrangement (for example, in a combined heat and (CHP) system in is which fixed frequency AC electric power for supply to the mains or grid is output from a frequency converter supplied with a variable frequency AC power input from an electrical generator driven by an internal combustion engine. The speed of the engine is varied by operation of a throttle controlled by a controller containing a predetermined engine map representing variation of engine speed as a function of the variation in electrical power output from the frequency converter to meet the demand of an external electrical load. On the load demand changing, the controller signals the frequency converter to give a changed new power output to meet the changed demand. The controller consults the map to determine the new engine speed corresponding to the new power demand and operates the throttle to cause the engine to run at the new speed.

Abstract: An electrical power generating arrangement (for example, in a combined heat and power system) in which electric power for supply to mains or grid is output from a generator driven via a continuously variable transmission (C.V.T.) by an internal combustion engine having a throttle. The throttle opening and ratio of the C.V.T. are controlled by a controller comprising a computer programmed with an engine map which is consulted by the computer when there is a change in an external electrical load power demand. For any load, the map indicates at which speed the engine should be run for optimum engine efficiency, the throttle opening is varied to attain that speed, and the controller varies the ratio of the C.V.T. to a value consistent with the desired engine speed.