The miniature power plant at the museum is a scaled model of the old Pelton-turbines utilised in the power plant.
The difference between the model and the originals is that the real versions were installed as double turbines rather than singular. That means that they have two turbines and two generators, while the model is singular. In addition to the turbine itself the miniature power plant has its own pipeline that supplies the turbine-wheel with water.
The miniature power plant works in the same way as its larger-scale cousins. You can see how the power of the water forces the wheel to spin and generate electrical power by utilizing friction and electromagnetic magnetization. The electricity is then transferred through electrical wires and used to light up a model of an apartment building.