Simulation-Based Investigation for Local Resonance Frequencies in Power Transformer Core
* Presenting author
Core resonance is one of the main phenomena that has always a negative effect on transformer noise level. Because of limitation of measuring the natural frequnecies of a core, only few varieties of changing core dimensions are possible. However, using simulation tools is more effective and can help initially to build a suitable model for daily use.Investigating the core in simulation environment as bulk mass simplyfies the duty to build a mathematical model to calculate the resonance frequencies based on core dimensions. However, this way is not presenting the reality, that each step of the core has its own shape modes and effective resonances frequencies as well. Considering each step geometry separately will lead to determine the local resonance frequencies and to find a solution for the steps, which have the undesirable resonance frequencies.The target is to find out the effective geometry factors of the step on the resulting resonance frequencies and shape modes. Moreover, the measured frequency spectrums for some tested core are studied and a correlation between the simulation results and measurements is studied. The focus covers core designs for 50 and 60 Hz, and the investigated frequency range lies between 100 and 1400 Hz.