Hi i am looking for practical examples for desining pid for power supply like what is the effect of changing this r or c on the stability of the power supply
thanks

 

You need to be much more specific. Topology, power requirements, circuit diagram, feedback loop, all of it.

 

In general, would you not be including a PID to keep your power supply stable in case there are loading effects? Your P, I, and D would have to be appropriately tuned for a circuit with specific characteristics so as to keep it stable.

As I recently found out, nothing beats prototyping, starting with circuit diagram and feedback loop.