any idea for poster presentation or some sort of working model on topics related electrical engineering?

Answer 1

How about simply showing the flow of energy from the falling water, steam from coal and from nuclear power though the transmission system to the distribution system to the breaker box and circuits in the house. Add pictures from the internet of the generators, towers, transformers, wires and breaker boxes.

Answer 2

I like mike1942f's idea. Here is a twist to it. Try the idea that all energy is solar. All of it. Sun shines on oceans, makes clouds, makes rain, fills reservoirs, turns generators, makes toast. Sun shines on forests, trees cut, firewood heats cabin. Sun shines on forests, forests get buried by time, forests turn to coal and oil, coal and oil burn in generating plants, makes toast. It is a sort of interesting idea. Short of nuclear, just about all our energy was originally sunshine.