In the following article, results of the investigation on the effect of feeding subsynchronous currents from the electric grid in the generator are presented. In the end, torsional oscillations of the shaft train are excited, which can reach very high amplitudes in case of resonance. In time with the torsional oscillations, the synchronous generated voltage induced in the stator winding oscillates, which leads to the feed of subsynchronous currents from the generator into the electrical network. The focus is directed to the effect of these currents in the system “generator-grid”. Therefore, different analytical approaches to subsynchronous power excitation are presented and evaluated. In particular, the analytical equations of generator power generated by subsynchronous electric currents are derived. This article shows that, in addition to the damping properties in dealing with torsional oscillations, the interaction between the grid frequency, the natural electrical grid frequencies and the mechanical torsional natural frequencies is also important.
Cite this paper
Humer, M. (2020). Torsional Oscillations Excited by Feeding in Subsynchronous Currents from the Grid into the Electrical Generator. Open Access Library Journal, 7, e7035. doi: http://dx.doi.org/10.4236/oalib.1107035.
Exnowski, S. andHumer, M. (2018) Subsynchronous Resonances in the Shaft Train of Large Turbosets and High Voltage DC Transmission. 23th International Conference on Electrical Machines, Alexandroupoli, Greece, 3-6 September 2018, 414-418.
https://doi.org/10.1109/ICELMACH.2018.8507243
Humer, M., Salzig, C. and Wirsen, A. (2020) Monitoring von Torsionsschwingungen als Folge von Netzinteraktionen, Essener Turbogeneratorentagung “Generatoren in konventionellen Kraftwerken, Windparks und Wasserkraftwerken”, Haus der Technik Essen, 18-19 February 2020, Germany.
Humer, M. and Golebiowski L. (2012) Subsynchrone Resonanzen im System Turbosatz-Netz/Entstehung und Auswirkung auf den Turbosatz, Haus der Technik, Seminar “Turbogeneratoren im Kraftwerk”, Essen, Germany.
Wirsen, A., Lang, P. and Humer, M. (2004) Systems for Monitoring and Analysing Torsional Vibrations in Turbine Generator Shaft Lines. Conference Proceedings of the 16th International Conference on Electrical Machines, Krakow, Poland, 5-8 September 2004, 855-856.
Humer, M. and Kulig, S. (2003) Measurement and Assessment of Torsion Oscillations in Turbogenerators by Using a Torque Sensor and Robust Observer. IEEE Industrial Electronics Society, Roanoke, Virginia, USA.
Humer, M., Golebiowski, L. and Kulig, S. (2011) Reduzierung der Turbosatzbeanspruchungen durch den Einbau des Kraftwerksentkupplungsschutzes. VGB PowerTech 8/2011, 91, 54-59.