in the political domain. The number of active players, including DER units and storage units etc., is rapidly growing and could easily reach millions. This brings unprecedented challenges to grid stability, reliability, security, and resiliency. The fundamental challenge is that future power systems will be power electronics based, instead of electrical machines based, with millions of non‐synchronous heterogeneous players. This is less of a power problem but more of a systems problem – power systems are going through a paradigm shift.
Adding an ICT (information and communications technology) system into power systems, hence the birth of smart grids, has emerged as a potential solution. However, this could lead to serious reliability concerns. On 1 April 2019, a computer outage of Aerodata affected all major US airlines, causing 3000+ flight cancellations or delays. This sends a clear warning to the power industry: ICT systems may be a single point of failure and similar system‐wide outages could happen to power systems. Moreover, when the number of active players reaches a certain level, the management of ICT systems is itself a challenge. What is even worse is that adding ICT systems to power systems opens the door for potential cyber‐attacks by anybody, at any time, from anywhere. There are numerous reports about this and, on 23 December 2015, hackers compromised ICT systems of three distribution companies in Ukraine and disrupted the electricity supply to 230 000 customers. The reliance of power systems operation on ICT systems has become a fundamental systemic flaw.
Another fundamental systemic flaw of current power systems is that a local fault can lead to cascading failures. On 16 June 2019, a blackout originating in Argentina's northeast struck all of Argentina and Uruguay, and parts of Brazil, Chile and Paraguay. There is a pressing demand to prevent local faults from cascading into wide‐area blackouts.
This book summarizes the author's profound thinking into these problems over the last 18 years and presents a theoretical framework, together with its underpinning technologies and case studies, for future power systems with up to 100% penetration of DERs to achieve harmonious interaction, to prevent local faults from cascading into wide‐area blackouts, and to operate autonomously without relying on ICT systems. Thus, it is possible to completely avoid cyber‐attacks. The theoretical framework, referred to as SYNDEM (meaning synchronized and democratized), adopts the synchronization mechanism of synchronous machines, which has underpinned power systems operation and growth for over 100 years, as its rule of law. Hence, the SYNDEM framework brings backward compatibility to current power systems. The underpinning technologies will turn power electronic converters into virtual synchronous machines (VSMs) and achieve legal equality among millions of non‐synchronous heterogeneous players, including flexible loads that have power electronic converters at the front end. This unifies and harmonizes their interface and integration with the grid, making it possible to achieve autonomous operation for power systems without relying on ICT systems. Hence, the SYNDEM theoretical framework and its underpinning technologies will significantly smooth the paradigm shift of power systems from the centralized control of a small number of large facilities to democratized interaction of a large number of relatively small generators and flexible loads, accelerating the large‐scale adoption of renewables while enhancing grid stability, reliability, security, and resiliency.
This book consists of one introductory chapter (Chapter 1) and five parts: Theoretical Framework (Chapters 2–3), First‐Generation VSMs (Chapters 4–14), Second‐Generation VSMs (Chapters 15–20), Third‐Generation VSMs (Chapter 21), and Case Studies (Chapters 22–25). In the introductory chapter, the outline of the book and the evolution of power systems are presented. In Part I, the SYNDEM theoretical framework and the ghost power theory are presented. In Part II, the first‐generation VSMs (synchronverters) are presented, together with their application in wind power, solar power, flexible loads, STATCOM, and motor drives, the removal of PLLs, the improvement to bound frequency and voltage, and the reconfiguration of virtual inertia, virtual damping, and fault ride‐through. In Part III, the equivalence between droop control and the synchronization mechanism is established at first. Then, the second‐generation VSMs (robust droop controllers) are presented, followed by universal droop control, the removal of PLLs, droop‐controlled flexible loads to provide continuous demand response, and current limiting converters to prevent cascading failure. In Part IV, the third‐generation VSM, which achieves passivity of itself and the whole system if it is open‐loop passive, is presented. In Part V, four case studies are presented, including a single‐node system based on a reconfigurable SYNDEM smart grid research and educational kit, a 100% power electronics based SYNDEM smart grid testbed, a home grid, and the Panhandle wind power system.
This book is suitable for graduate students, researchers, and engineers in control engineering, power electronics, and power systems. The SYNDEM theoretical framework chapter is also suitable for policy makers, legislators, entrepreneurs, commissioners of utility commissions, utility personnel, investors, consultants, and attorneys. The book covers various challenging problems in the control of power electronic converters, distributed generation, wind power integration, solar power integration, microgrids, smart grids, flexible AC transmission systems, etc. It can be also adopted as a textbook for relevant graduate programs. Actually, it has been adopted as the textbook for ECE 537–Next Generation Smart Grids at Illinois Institute of Technology since 2018.
Acknowledgments
It is Father's Day as I am writing this. I cannot help but miss my parents, who live 12,000 km away from me. Needless to say, it is they who have planted the seeds for everything in this book. They nurtured me to keep being upright and taught me to serve the society wherever I am. They are like a mountain in my home town, constantly providing me with energy, courage, and calmness. There are many words I can say to thank them but, whatever I say, it is never enough to express my gratitude for what they have given me. There are many things I can do to thank them but, whatever I do, it is never enough to show my appreciation for them. The only thing that makes me feel slightly better is to call them once a week while I keep moving forward every day – I have been doing this for nearly 20 years. Many teachers and professors have taught me with their life‐long experiences, valuable wisdom, and profound knowledge, which have directly contributed to the development of the technologies described in this book. “Teacher for one day, father forever,” as a Chinese proverb says. I will always remember them. This book is dedicated to two of them, my first‐grade teacher Ms. Luo and my third‐grade teacher Ms. Lin for their inspirational words. This book holistically summarizes the intensive and extensive thinking I have had about future power systems since 2001. Over the last 18 years, I have had the great opportunity to advance this line of research with collaborators, postdoctoral researchers, and PhD students, including Mohammad Amin, Frede Blaabjerg, Dushan Boroyevich, Jianyun Chai, Chengxiu Chen, Joseph M. Guerrero, Tomas Hornik, George Konstantopoulos, Miroslav Krstic, Fred Lee, Hong Li, Zijun Lyu, Zhenyu Ma, Wen‐Long Ming, Long Nguyen, Beibei Ren, Tiancong Shao, Wanxing Sheng, Márcio Stefanello, Yeqin Wang, George Weiss, Yu Zeng, Xiaochao Zhang, Yangyang Zhao, Qionglin Zheng, and Yuanfeng Zhou, just to name a few. Their contributions to the work included in this book are greatly appreciated. I would like to thank Royal Academy of Engineering, U.K. and the Leverhulme Trust for the award of a Senior Research Fellowship during 2009–2010. Their visionary decision has made a significant impact on my research in this area. I would also like to thank the Engineering and Physical Sciences Research Council, UK for their support (under Grant No. EP/J01558X/1 and EP/J001333/2), which has facilitated me to make some major breakthroughs in this area. It is a great honor for me to be invested as the Max McGraw Endowed Chair Professor of Energy and Power Engineering and Management at Illinois Institute of Technology. Max McGraw (1883–1964) founded McGraw Electric Company in 1900 when he was 17 years old and acquired Thomas A. Edison, Inc. in 1957 to form the McGraw–Edison Company, which employed 21,000 people in 1985 when acquired by Cooper Industries. He never retired. He was so visionary and established McGraw Foundation in 1948 with the mission to provide financial assistance for educational and charitable purposes in furtherance of the public good and promoting the well‐being of all humanity. He will be remembered forever. The support of our industrial partners and advisors has always been instrumental for our research. I am particularly grateful to Phillip
