Transient Operation Analysis of a Cogenerating Micro-Gas Turbine

A cogenerating micro gas turbine, operating with a partially recuperated thermal cycle based on a by-pass option towards the heat recovery boiler, is examined under the point of view of the transient developments. The latter are induced by variations in both electrical and thermal loads and are strongly affected by the fuel supply law and by the response delay of the rotating and stationary components. Several unsteady cases are investigated, by comparing different time changes in the fuel flow rate under constant or variable speed operating conditions. These examples allow identification of the most efficient fuel control laws, together with some possible critical conditions induced by either instabilities in the rotating components or by unreliable fuel/air ratios during the transient development.