The influence of rotor damping structure on asynchronous operation of turbine generators during loss of field

Field failure of a turbine generator is one of the common faults of power system. The asynchronous operation of a turbine generator during loss of field can avoid equipment damage and large-scale blackout. It also can improve the reliability of the generator. The turbine generator's rotor damping effect which provides asynchronous torque plays an important role in asynchronous operation of turbine generator during loss of field. In order to study the influence of rotor damping structure on asynchronous operation of turbine generator, we establish a field-circuit coupled time-stepping finite element model and test this model by the experiment on a 7.5 kW model machine. With this model we study the influence of rotor iron core, rotor slot wedges and damping bars on the asynchronous operation of a 300 MW turbine generator during the loss of field. Meanwhile, we calculate the asynchronous operation ability of the turbine generator during the loss of field with different rotor damping structures. At last, we reveal that rotor slot wedges play an important role in asynchronous operation of turbine generator during loss of field.