An electric power generation system and a method in an electric power generation system. The system comprising one or more generators for producing electrical energy, each generator being arranged to be driven with a corresponding prime mover, wherein the generators are multiphase AC generators adapted to generate a multiphase voltage having a frequency and an amplitude, the phase outputs of the generators are connectable to a common multiphase bus for distributing the electrical energy generated by the AC generators, the system comprises further means for providing independent reference values for a rotational speed of the prime movers and for amplitude of the multiphase voltage, the rotational speed of the prime movers defining the frequency of the multiphase voltage, and the system is adapted to operate in at least three operation points on the basis of the provided independent reference values, an operation point being defined by a ratio of the amplitude of the multiphase voltage to the frequency of the multiphase voltage, wherein the at least three operation points are different.