This book includes original, peer-reviewed research papers from the 2021 International Top-Level Forum on Engineering Science and Technology Development Strategy -- the 6th PURPLE MOUNTAIN FORUM on Smart Grid Protection and Control (PMF2021), held in Nanjing, China, on August 14-22, 2021. The accepted papers cover the following topics:1. Advanced power transmission technology2. AC/DC hybrid power grid technology3. Power Internet of Things Technology and Application4. Operation, control and protection of smart grid5. Active distribution network technology6. Power electronic technology and...