The influence of rotor slot wedge material and conductivity on first swing stability of turbine generator

The turbine generator rotor damping system consists of damping bars, iron core and slot wedges. The rotor slot wedges are not only preventing the field windings out of slot, but also provide the damping effect to keep power system stability. Since there are several materials to choose from and their conductivity is different, it is necessary to study the influence of rotor slot wedge material on First Swing Stability (FSS). In this paper, we establish the Field-circuit-network coupled time-stepping finite element model, which is verified by the experiment of model machine. With a 300MW turbine generator as an example, the FSS limits of turbine generator with rotor slot wedge made from aluminum, copper base bronze and stainless steel are calculated and compared; the key factor affecting the FSS limit is obtained. In order to find the optimal material for FSS improvement, the FSS limits are calculated with the conductivity of rotor slot wedge in the range of 0 to a al (conductivity of aluminum). The result shows that the FSS limit of turbine generator with the rotor slot wedge made from stainless steel is larger than that made from aluminum and copper base alloy. The variation law of FSS limit with the change of rotor slot wedge conductivity is revealed. The results provide important reference for improving the FSS in the design of turbine generator.