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)
Protection for a ring bus is the protection for the connected lines and transformers. There is no separate bus protection because every part of the bus is protected by the connected circuit protection.
In addition to the resources given by Isuengineer, see
Also see ANSI/IEEE C37.91, Guide for Protective Relay Applications to Power Transformers, ANSI/IEEE C37.97, Guide for Protective Relay Applications to Power System Buses, and ANSI/IEEE C37.113, Guide for Protective Relay Applications to Transmission Lines.