Zweiphasiger Betrieb von großen elektrisch erregten Synchronmaschinen

Large grid-connected electrically excited synchronous generators (EESG) in the medium MVA range (1…20MVA) and medium voltage (kV) are usually designed for 3-phase symmetrical operation. In rare exceptional cases, however, there may be applications (e.g., test bench applications) in which both 3-phase and 2-phase operation should be possible, whereby 2-phase operation here actually refers to asymmetrical single-phase operation via 2 strands with the 3rd machine strand switched off. In this extremely asymmetrical operating case, the damper cage, which in symmetrical 3-phase operation normally serves only as a start-up cage and is intended to dampen compensation and transient processes, plays a special role. In the extreme case of unbalanced operation, the losses in the damper cage are disproportionately higher, which must be taken into account in the machine design and, in particular, in the design of the damper cage, in addition to the high mechanical loads (torque fluctuations). The presentation deals with the calculation of losses in the damper cage and its influence on the operating behavior of the machine in the special case of 2-phase operation using transient FEM with ANSYS Maxwell.