What are the energy transformation that might occur in a power plant?

Energy is not a physical unit. It is a philosophical concept and an accounting technique used to analyze mechanical and chemical exchanges. In nuclear physics it is defined as a wavelength of light, in biology it is a synonym for metabolism, and in public utilities they say energy when they mean connectivity.

If you want to talk about what happens in a power plant you need to find the words that specifically apply to your topic. Otherwise nobody knows what you are talking about.