Influence of Rotor Structure on Field Current and Rotor Electromagnetic Field of Turbine Generator Under Out-of-Phase Synchronization

Out-of-phase synchronization (OPS) fault may occur to the turbine generator used in gas-steam combined cycle units, which may seriously endanger the operation stability of the generator unit. To investigate the influences of rotor structure on field current and rotor electromagnetic field of a turbine generator under OPS, a 2-D field-circuit-grid coupled model (FCGCM) of the 150-MW turbine generator is established. By using the established FCGCM, the influences of rotor slot indexing number (RSIN) and magnetic permeability of the rotor wedge on field current under OPS of 180° were studied. A magnetic no uniform coefficient (MNC) was proposed to evaluate rotor magnetic field nonuniformity. The relations of the field current oscillation ratio and MNC to RSIN and magnetic permeability of rotor wedge were investigated. The results could provide a theoretical basis for the electromagnetic mechanism of the turbine generator under OPS faults.