Figure 5 - 38 illustrates the physical layout of the two shafts. It can be observed that different stages of the turbines are supported by the same shaft. This layout can potentially induce torsional
oscillations between different masses on the same shaft.
The model of the thermal turbine generator has two shafts, each with either one or five masses. In addition, the cross-compound turbine generator model allows the application of a mechanical torque to each turbine mass. Since the masses are hard-coded, shaft models with a mass number other than 1 or 5 will be simulated by setting the inertia of non-existent masses to very small values and the rigidity factors adjacent to the shafts to a very high value.
Shaft Model with Spring Masses