This book features a collection of high-quality, peer-reviewed research papers presented at the 3rd International Conference on Smart Electrical Grid and Renewable Energy (SEGRE 2025), held in Mianyang, China, from July 25th to 28th, 2025. It covers up-to-date, cutting-edge research on electrical and power engineering, smart grid operations, and sustainable energy. This book provides an opportunity for researchers and academics, as well as practitioners from industry, to publish their ideas and recent research developments on all aspects of electrical and power engineering, smart grid operations, sustainable energy, their applications, and other related areas.