Caisheng Wang, Lingling Fan
Analysis, design, implementation, and control of an engineering system always start with modeling. On the one hand, modeling is always a process of simplification. For example, we can simply model a battery by an ideal constant voltage source and a light bulb by a resistor. Then, we can analyze the circuit and calculate circuit quantities (current, voltage, power, etc.). On the other hand, depending on the scope of study, we need to have enough details or a certain level of fidelity in the models so that meaningful studies can be carried out. For example, copper polygons in low-frequency (e.g., ≤10 kHz) printed circuit boards (PCBs): they can be simply treated as copper conductors using lump parameters, while we should use transmission line theory when handling polygons in high-frequency (e.g., over gigahertz) PCBs.
From a microgrid with a handful of distributed energy resources, such as solar panels and energy storage, and a group of local loads to a large, interconnected power system with thousands of components and even millions of subcomponents and systems, we need a variety of tools to help us to analyze, design, implement, and operate such systems. Electromagnetic transient (EMT) analysis is one of the important tools. In a world increasingly driven by sustainable energy development and green transportation, the role of EMT analysis cannot be overstated. It is the hidden force behind the scenes, the technology that powers the clean energy revolution, enables efficient transportation electrification, paves the way for carbon neutrality, and propels the electric vehicle industry into the future.
This issue is on EMT analysis fundamentals, methods, tools, data preparation, and applications. Eight remarkable feature articles, along with two columns authored by leading experts from around the globe, shed light on this important field, encompassing a wide spectrum of topics. From system and component modeling, multidomain and multiphysics modeling, to advanced simulation and emulation methods, such as hardware-in-the-loop (HIL), and applications in the design and implementation of zero-emission energy systems, this issue takes us on a journey through the heart of EMT analysis.
Brian K. Johnson from the University of Idaho contributes to the “Technology Leaders” column with “Electromagnetic Transient Simulation: Moving to the Mainstream.” He provides his insightful perspective on the evolution of EMT analysis from a highly specialized tool for a small group of people at the beginning to a common tool today for interconnection studies for inverter-based resources (IBRs) and design and implementation of transportation electrification systems. The power systems around the world have gone through significant changes during the same period of time. When the first author first saw a 500-kV transmission line and tower in the 1980s, he was really fascinated as an elementary school student. Now, there are transmission lines of over 1,000 kV, and the global electricity generation from wind and solar has gone up from almost zero in 1982 to over 3 trillion kWh in 2022. EMT tools have a unique contribution to this fantastic development.
With the promise that computer simulation tools can offer, Peter Wung penned the “Viewpoint” column titled “To Test or Not To Test?” to remind the reader that computer simulation tools are based on physics we know, and in the territories that physics are still to be learned, the trustworthiness of computer simulation results remains a question. Fortunately, for electromagnetism, power electronic circuits, and controls, we have the full confidence of physics and therefore computer simulation tools have been vastly deployed.
The first article is contributed by Xin Ma and Xiao-Ping Zhang from the University of Birmingham, providing a brief history of EMT development, and reviewing the mathematical fundamentals (such as trapezoidal rule in numerical analysis) of EMT models and solutions of power systems with components, such as RLC branches and synchronous machines. The second article is written by Dragan Jovcic, an expert on high-voltage dc from the University of Aberdeen. This article provides a great introduction to modeling power electronic converters, particularly via the average value approach based on a rotating frame. Power converters have become indispensable units in modern power systems. Power converters are the core equipment for most renewable and clean alternative energy systems, such as wind, solar, and fuel cell generation systems, as well as for transportation electrification. It has been estimated that 80% of utilized electricity will flow through power electronics devices by 2030. Analytical converter modeling complements detailed digital simulation and can expedite system studies.
The third feature article is the outcome of a collaboration between Kai Strunz from Technische Universität Berlin, Ying Chen of Tsinghua University, and Yue Xia from China Agricultural University. The article introduces the shift frequency method for frequency-adaptive simulation of wide-scale transients in power systems. The so-called frequency-adaptive simulation of transients method can handle power system transients in a vast range, from minutes down to microseconds or even faster for the EMTs of traveling waves in an efficient and accurate manner.
Electrical machines are the core equipment in power systems and are used in almost every aspect of our daily life. Modeling and simulation of electric machines play a critical role in EMT studies. The fourth article, coauthored by industry expert Erfan Mostajeran (from Electric Power Engineers LLC.) and academic researchers Navid Amiri, Seyyedmilad Ebrahimi, and Juri Jatskevich (from The University of British Columbia), provides a comprehensive review of this important topic of electrical machine modeling. Typical electrical machine models introduced with appropriate details in the article represent essential electromagnetic and mechanical transient phenomena. Electrical machines with more than three (e.g., five, six, nine, 12, etc.) electrical phases are also introduced in the article for applications with some specific requirements, such as increased reliability and fault-tolerant operation. Discussions on further improvement of the electrical machine model’s fidelity, numerical accuracy, and computational efficiency are also given in the article. Electrical machines are the core equipment in power systems and are used in almost every aspect of our daily life. Modeling and simulation of electric machines play a critical role in EMT studies.
The fifth article from the University of Alberta by Chengzhang Lyu and Venkata Dinavahi covers another important aspect of EMT studies: multidomain modeling of EMTs. Zero-emission marine vessels powered by fuel cells with battery storage are presented in the article as an interesting example of EMT modeling across electrical, chemical, hydraulic, and thermal domains. HIL emulation has often been considered for expediting the simulation process and for obtaining more accurate results. An FPGA-based, real-time HIL emulation system, called adaptive compute acceleration platform, is introduced for emulation studies of a zero-emission marine vessel.
The sixth article, contributed by Dionysios Aliprantis and Steven Pekarek from Purdue University, continues the discussions on computational electromagnetics for electric machine analysis, modeling, and design. Computational electromagnetics has played and will continue to play an even more important role in transportation electrification thanks to the recent advances in computing. After introducing the finite element method and the method of moments in the article, the authors provide their perspective on multiphysics modeling and 4D (space and time) simulation studies of electric machines.
The seventh article is another great piece of international collaboration work between Jean Mahseredjian, Mohammed Naidjate, and Mehdi Ouafi from Polytechnique Montreal and Juan Antonio Ocampo Wilches from Réseau de Transport d’Électricité in France. This article introduces a comprehensive and unified environment that enables the exploration of power systems across various modeling levels, encompassing load-flow analysis and extending to intricate time-domain simulations featuring IBRs. The authors first start with the initialization of IBR circuits and parallel computations for practical system problems. Then, they move on to demonstrate that the time-domain accuracy level can be further increased through detailed and integrated modeling of magnetic circuits in the proposed unified environment.
Last but not least, the eighth feature article in this issue is on data preparation for EMT simulation studies. The authors, Taku Noda and Tomo Tadokoro from Grid Innovation Research Laboratory, Central Research Institute of Electric Power Industry (CRIEPI), Japan and Takashi Dozaki from National Renewable Research Laboratory, discuss this important topic, and present application examples of the developed automatic data generation system in Japan. Simulation data preparation, although not directly focused on EMT modeling, is an indispensable segment and has become the most time-consuming part of EMT studies today.
There are also two timely newsfeeds in this issue. One newsfeed is on the past IEEE Transportation Electrification Conference and Expo (ITEC) conference held in Detroit, MI, USA, contributed by Matt Woongkul Lee from Michigan State University. A panel consisting of academia and industry experts was successfully organized by Dr. Lee in the conference to discuss high-performance rare-earth magnet-free electric machine design. The panel presentations and discussions underscore the importance of collaboration, innovation, and optimization to unlock the full potential of rare-earth magnet-free designs, which are critical to the sustainable development of transportation electrification. The other newsfeed is provided by Taku Noda from CRIEPI, Japan about the 2023 International Conference on Power Systems Transients (IPST). This year’s IPST hosted about 200 EMT experts around the world, seeking solutions for up-to-date and long-standing issues in the power system EMTs. We believe the readers will find the detailed descriptions of the conference interesting. More interestingly, beautiful pictures are also shared in this newsfeed.
B. K. Johnson, “Electromagnetic transient simulation: Moving to the mainstream,” IEEE Electrific. Mag., vol. 11, no. 4, pp. 6–7, Dec. 2023, doi: 10.1109/MELE.2023.3320482.
P. Wung, “To test or not to test?” IEEE Electrific. Mag., vol. 11, no. 4, p. 96, Dec. 2023, doi: 10.1109/MELE.2023.3320529.
X. Ma and X.-P. Zhang, “Basics of electromagnetic transients: Underlying mathematics,” IEEE Electrific. Mag., vol. 11, no. 4, pp. 8–19, Dec. 2023, doi: 10.1109/MELE.2023.3320485.
D. Jovcic, “Rotating frame, average value converter modeling: Basic principles in building analytical models,” IEEE Electrific. Mag., vol. 11, no. 4, pp. 20–28, Dec. 2023, doi: 10.1109/MELE.2023.3320486.
K. Strunz, Y. Chen, and Y. Xia, “Bridging scales with the shift frequency: Frequency-adaptive simulation of multiscale transients in power systems,” IEEE Electrific. Mag., vol. 11, no. 4, pp. 29–37, Dec. 2023, doi: 10.1109/MELE.2023.3320487.
E. Mostajeran, N. Amiri, S. Ebrahimi, and J. Jatskevich, “Electrical machines in electromagnetic transient simulations: Focusing on efficient and accurate models,” IEEE Electrific. Mag., vol. 11, no. 4, pp. 38–53, Dec. 2023, doi: 10.1109/MELE.2023.3320508.
C. Lyu and V. Dinavahi, “Zero-emission marine vessels: Multi domain modeling and real-time hardware-in-the-loop emulation on adaptive compute acceleration platform,” IEEE Electrific. Mag., vol. 11, no. 4, pp. 54–63, Dec. 2023, doi: 10.1109/MELE.2023.3320509.
D. Aliprantis and S. Pekarek, “The unsung hero of the electric vehicle revolution: The role of computational electromagnetics in electric machine design and analysis,” IEEE Electrific. Mag., vol. 11, no. 4, pp. 64–68, Dec. 2023, doi: 10.1109/MELE.2023.3320510.
J. Mahseredjian, M. Naidjate, M. Ouafi, and J. A. O. Wilches, “Electromagnetic transients simulation program: A unified simulation environment for power system engineers,” IEEE Electrific. Mag., vol. 11, no. 4, pp. 69–78, Dec. 2023, doi: 10.1109/MELE.2023.3320511.
T. Noda, T. Tadokoro, and T. Dozaki, “Automatic generation of power system simulation data cases from utility databases: Introducing a new technology,” IEEE Electrific. Mag., vol. 11, no. 4, pp. 79–85, Dec. 2023, doi: 10.1109/MELE.2023.3320521.
W. Lee, “Rare earth magnet-free electric machine design: Unlocking sustainable electrification,” IEEE Electrific. Mag., vol. 11, no. 4, pp. 88–89, Dec. 2023, doi: 10.1109/MELE.2023.3320522.
T. Noda, “International conference on power systems transients 2023,” IEEE Electrific. Mag., vol. 11, no. 4, pp. 90–92, Dec. 2023, doi: 10.1109/MELE.2023.3320556.
Digital Object Identifier 10.1109/MELE.2023.3320479
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