Hello, my name is Brandon. I have designed numerous protection schemes for ring-bus switchyards. There are a couple of books that go into general protection schemes but I am not sure how specific they get into ring-bus configurations. They are,
1. Protective Relaying Theory and Applications - published by ABB
2. Protective Relaying Princples and Practices - Lewis Blackburn
3. The Art and Science of Protective Relaying - published by GE (this one is a free download through GE's website)