INVESTIGATION OF ELECTROMAGNETICALLY INDUCED VIBRATIONS IN ASYNCHRONOUS HYDROGENERATOR

Abstract

In India, the first variable speed Pump Storage Power Plant (PSPP) having four nos. of 250 MW Doubly Fed Induction Machine (DFIM) totaling a capacity of 1000 MW recently started operation at the Tehri dam of Uttarakhand state. Variable speed Pump Storage Power Plant (PSPP) employing a Doubly Fed Induction Machine (DFIM) is an acceptable option for sites with wide variation in water head since they provide variable speed operation with reduced power converter rating and high dynamic stability. In DFIM, power converters on the rotor side function as an excitation system regulating the machine's real and reactive powers based on set points (reference) and feedback signals from various sensors. Consequently, in order to maintain the exponential rise in renewable energies, the sector of energy conversion must improve electrical machine performance. These performances are assessed based on standards unique to each of the physical domains i.e., thermal management, control, power converters, losses in electromagnetic materials, and acoustics—involved in the design of electrical machines. Noise and vibration are associated with a number of difficulties, including mechanical fatigue (in the energy sector, such as hydroelectric generators), security (in military applications), vibroacoustic comfort (in rail, automobile, or home applications), and safety and health issues (in industrial environments). Vibrations can degrade working conditions, limiting machine's life and raising maintenance costs. Standards are mostly used to evaluate the impact on the environment. However, individual people's subjective feelings vary depending on the circumstances. The Covid-19 health issue and containment efforts have brought attention to how pervasive noise pollution is in our communities. This work focuses on the vibrations from electromagnetic sources in doubly fed induction machine. Electromagnetic fields, which produce parasitic forces in active structures, are associated with these particular vibrations. The interaction between these magnetic forces and the structural mechanics causes noise and vibration. Nowadays, manufacturers of electrical machines are being forced by economic limitations to make lighter machines, which raises the vibration level and makes machine structures more pliable. Furthermore, the behavior of electromagnetic fields and, eventually, magnetic forces can be greatly impacted by modifications in topology as well. Reducing vibrations without sacrificing electromechanical performance is the primary challenge in machine design. A comprehensive literature survey is carried out in the area of electromagnetic vibrations in electrical machines such as squirrel cage induction machines, synchronous machines, permanent magnet synchronous machines etc. The source, effect, and cause for electromagnetic vibrations in DFIM is studied through simulation and experimental tests. From the literature, it is found that the electromagnetic vibration in large rated DFIM stator serving to hydropower applications is not yet explored enough.