That is a tall order you are asking for. The first step is to look at the NETA ATS/MTS and IEEE standards (I would start with the color books). For power factor testing, Doble is the pioneer, with newer test sets providing updated test procedures (Omicron, Megger, etc.). For Relay testing, there are numerous companies out there that provide in-person training, but I would visit Chris Werstiuk for a baseline and move up from there (
https://relaytraining.com/), his books are easy to read and understand with basic algebra/trig understanding.
Another great resource for Testing principles is Paul Gill's book:
Electrical Power Equipment Maintenance and Testing.
As for design, I would recommend looking at University courses, as their curriculum can point you to specific text books on Substation theory which assist with design.
Lastly, NERC/FERC controls all utility guidelines.