Assessment of Operation Mode Influence on Reliability of Generating Equipment in Terms of Reactive Power Control

Since the mid-1980s, Russia’s power systems have been having problems with maintaining the required GOST voltage levels in high-voltage electrical grids, and with the modes of operation of turbine generators (TGs) in terms of reactive power load. These problems have recently worsened owing to the generation of reactive power by 220 – 500 kV transmission lines and the insufficiency of inserted reactive power compensation devices. To normalize the voltage, TGs operating on 220 – 500 kV buses are switched to reactive power consumption modes by commands of system operator, which helps reduce voltage levels but, over time, expedites wear of these TGs and, in some cases, causes emergency shutdowns due to destruction of the end zones of the active steel of stators. This study presents information regarding the influence of operating modes in terms of reactive power control on the technical condition of the main electrical equipment of power plants. Reactive power consumption modes lead to expedited destruction of end stack tooth zones and reduction in the service life of TG stators with both unbaked and baked stacks of active steel. Systematic operation in reactive power consumption modes degrades and destructs the end zones of the TG core; this has repeatedly resulted in emergency shutdowns due to the cutting of stator winding insulation by unabated and broken fragments of active steel sheets. This study briefly reviews disturbances in the generating equipment caused by its operation in maneuvering modes of reactive power control. It presents data on disturbances, induced by the abovementioned causes, in operation of the thermal power plants of the Unified Energy System of Russia. It is focused on the operation modes of TGs in the deep underexcitation mode. © 2023, Springer Science+Business Media, LLC, part of Springer Nature.