For power system operations: "Power System Stability and Control" by Prabha Kundur (https://www.amazon.com/System-Stability-Control-Prabha-Kundu...)

It is the bible of modern power system operations, and it will become more and more important as more renewable energy comes online. Understanding the concepts presented in this book is the difference between "why haven't we hit 100% renewables yet?!" and "we need market incentives for inertial ancillary services".

Right now I'm reading this book about this topic: Power System Stability and Control by Prabha Kundur https://www.amazon.com/System-Stability-Control-Prabha-Kundu...