Book excerpt: 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 technology 2. 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 application7. New technology of substation automation8. Energy storage technology and application9. Application of new technologies such as artificial intelligence, blockchain, and big data10. Application of Information and Communication Technology11. Low-carbon energy planning and security12. Low-carbon operation of the power system13. Low-carbon energy comprehensive utilization technology14. Carbon trading and power market15. Carbon emission stream and carbon capture technology16. Energy saving and smart energy technology17. Analysis and evaluation of low-carbon efficiency of power system18. Carbon flow modelling in power system operationThe papers included in this proceeding share the latest research results and practical application examples on the methodologies and algorithms in these areas, which makes the book a valuable reference for researchers, engineers, and university students.