Electrophysical Method for Identifying the Causes of Excessive Hydro Generator Vibration

This article analyzes the operation of hydro generators based on the operation modes of a hydroelectric power plant operating in the Arctic zone of the Russian Federation. The main load of the hydropower plant is an aluminum smelter. The nonlinear load of the smelter is a powerful source of harmonic disturbances. This load produces current and voltage distortions not only in the electrical networks of the smelter but also in those of the city and in generating voltage busbars of the hydropower plant. As a consequence, higher harmonics cause additional losses in the supply networks and have a negative impact on the hydro generators’ condition. The article analyzes the influence of current impacts of the smelter load on the hydro generators under imbalanced conditions by estimating torsional and tangential vibrations emerging in the generators. The tangential forces of double frequency (100 Hz) have been shown to produce practically no significant vibration displacement when detuning the natural frequency of the basket-type end-winding parts. The values of vibration and surge displacement increase significantly in the near-resonance zone. The intense impact of superimposed surge currents has been shown to result in reduction in the hydraulic turbines’ service life and increase in frequency of repairs.