A Microturbine Model including its Control for the investigation of the effects of Distributed Generation in distribution networks

The paper proposes a detailed model of the thermal and mechanical part of a microturbine; in fact this model accounts for three control loops: a speed controller (for primary frequency control), an acceleration control loop, which limits the rotor acceleration in case of sudden loss of load or in case of start-up, and a controller which limits the temperature of the exhaust gases below the maximum admissible temperature. Moreover the paper adopts a PV (active power – voltage) control of the inverter for the microturbine operation on the grid; the usual scheme adopted is a PQ (active power – reactive power) control, which regulates the values of active and reactive powers injected by the inverter into the grid. The use of a PV control scheme allows to evaluate the contribution of microturbines to voltage support in distribution grids. In case of isolated operation a Vf (voltage – frequency) scheme is adopted. A test grid is implemented and the results of the simulations are described and discussed.