A method of operation of a turbogenerator system is described. The system comprises a plurality of turbogenerators provided in parallel and in fluid communication with a gas stream. The method comprises identifying one or more of the turbogenerators which are currently operating closest to their maximum power output, and adjusting the speed of one or more of the turbogenerators to cause the power outputs of the plurality of turbogenerators to become more similar. In this way, it is possible to match the power output of the plurality of turbogenerators.