A New Approach for Protection of Turbine-Generator Shaft Against Axial Deflection in Non-Rotating Conditions

The operation of turbine generator of the thermal units leads to the high heat in the shaft and other rotating elements. Considering the related thermodynamic constraints, a controlled reduction of rotational speed is required to protect the shaft against the overheating and the axial deflection. As a common practice in current power systems, the “Turning Gear”, which is a mechanical protection system, is used for this purpose. Due to the costly maintenance and economic losses caused by the shaft deflection that may cause the generator outage, this research proposes a parallel protection for the shaft of turbine generator using the control of armature in-feed and excitation system. The success of this approach is not only confirmed by the simulation studies, but also consistent with the experimental test results.