Analysis of Load Noise Components in Small Core-Form Transformers

We propose load noise analysis components for small core-form transformers (1 MVA–20 MVA) using computational fluid-structure coupled calculations that consider the electromagnetic force, transformer structure and fluid (oil). The proposed technique has two beneficial aspects: coil modeling using shell elements of the finite element method (FEM), and acoustic noise analysis using a combination of boundary element method transmission path simulation and FEM structural simulation. The shell element model, which includes structural bending information, is less computationally intensive for simulations than solid models because it uses larger element sizes. Lighter simulations enable easier redesign for noise reduction. Additionally, division of the simulation process into individual structural vibrations, transmission paths, and radiation processes makes it easier to find a remodeling point without performing a complete simulation. We illustrate the importance of avoiding coincidence of the natural frequencies of the coils and the electromagnetic force and present a practical noise reduction study. This technique can be implemented using a light simulation that was proposed to confirm the remodeling effects. Using the proposed analysis method along with a ray tracing method, we can construct a frontloading design simulation tool to determine the transformer specifications and the substation's geographical features.