EV Integration and the SYNDEM Smart Grid Architecture

Electric vehicles (EVs) offer a promising solution to electrify transportation for potential greenhouse gas reductions and cost savings. EVs are also identified as flexible resources for grid integration with the ability to mitigate the increasing complexity issues of the grid, e.g., the duck curve caused by increasing penetration of renewables. The BP Energy Outlook predicts that about 100 million EVs will be on the road worldwide by 2035 [1]. 

Challenges for EV Grid Integration

The impact of simultaneously charging many EVs’ batteries from the grid would change the overall load profile of the grid significantly. The traditional charging behaviors of EVs are irresponsible to the electrical grid because they are only regulated by the customer sides. The simultaneous charging of a large number of vehicles can degrade grid performance, such as bad power quality with frequency drops and/or voltage deviations, reduced operation efficiency with increased peak power demand, requirement of large ancillary services, even the blackout of the whole power system if EVs are not charged properly. 

On the other hand, EVs can also serve as energy storage systems and operate in the vehicle-to-grid (V2G) mode to feed power to the utility grid when needed. As a result, integrated V2G systems can provide grid support with ancillary services, facilitate easy integration of renewable energy resources, compensate intermittent supplies and time-varying demands, and enable emergency backup power in grid outages and disaster-recovery efforts.

Virtual Synchronous Machines (VSM) for EV Grid Integration

It is well known that synchronous machines (SM) can synchronize with each other or with the power grid autonomously, without the need for external communication. This has underpinned the organic growth and operation of power systems for over 100 years. Recent research has shown that power electronic converters can be controlled to possess the intrinsic synchronization mechanism of SM. Such converters are called virtual synchronous machines (VSM) or cyber synchronous machines (CSM) [2]. Therefore, EVs that have power electronic converter interfaces with the grid, can be equipped with the intrinsic synchronization mechanism of SM and controlled to behave like VSM. 

This turns EVs into synchronous players so they can provide (virtual) balancing inertia in the same way as conventional SM. This approach tackles the challenge faced when simultaneously charge a large number of EVs: each EV can actively participate in the voltage and frequency regulation of the power system. In this way, the integration of EVs has a plug-and-play feature without the need of additional communication networks. In addition, when EVs are connected to the electrical grid and operated as the VSM, their virtual inertia can be reconfigured to improve system stability. 

SYNDEM Smart Grid Architecture 

In addition to EVs, the VSM technology can also be applied to power electronic interfaces in other generators and loads. Future power system will be power electronics based with a huge number of players at the supply side, inside the grid, and on the demand side. For example, renewable sources are connected to the grid through power electronic converters. In transmission and distribution networks, there are many power electronic converters, such as high-voltage direct current (HVDC) links and flexible ac transmission systems (FACTS) devices. On the load side, many loads such as motors, internet devices and LED lights, will also be connected to the grid through power electronic converters. These power electronic converters can all be controlled to possess the synchronization mechanism of conventional synchronous machines and behave as VSM, leading to the synchronized and democratized (SYNDEM) smart grid architecture for next-generation power systems shown above. This unified grid architecture and the associated technologies are expected to be game changer for grid – as reported by Midwest Energy News [5]. Live discussions and future updates about this are available at https://www.linkedin.com/groups/7061909.

The SYNDEM smart grid architecture featured by Midwest Energy News [5]

Further Reading
[1]. https://www.bp.com/en/global/corporate/energy-economics/energy-outlook/electric-cars-and-oil-demand.html
[2]. Q. C. Zhong, "Power Electronics-enabled Autonomous Power Systems: Architecture and Technical Routes," in IEEE Transactions on Industrial Electronics, vol. 64, no. 7, 5907-5918, July 2017, doi: 10.1109/TIE.2017.2677339. 
[3]. Q. C. Zhong, Power Electronics-Enabled Autonomous Power Systems: Next Generation Smart Grids, Wiley – IEEE Press, 2017.
[4]. Q.-C. Zhong, "Synchronized and Democratized Smart Grids To Underpin The Third Industrial Revolution", in Proceeding of the 2017 IFAC World Congress, Toulouse, France, July 2017.
[5]. http://midwestenergynews.com/2017/09/13/illinois-engineers-invention-expected-to-be-game-changer-for-grid/ 

 

Dr. Qing-Chang Zhong, an IEEE Fellow and an IET Fellow, received the Ph.D. degree in control and power engineering from Imperial College London, U.K., in 2004 and the Ph.D. degree in control theory and engineering from Shanghai Jiao Tong University, China, in 2000. He is currently the Max McGraw Endowed Chair Professor in Energy and Power Engineering at Illinois Institute of Technology, Chicago, USA and the Founder of Syndem LLC (www.syndem.com). Having been appointed as a Distinguished Lecturer of three IEEE societies (Control Systems, Power Electronics, and Power and Energy) and an Associate Editor of four IEEE Transactions, he is well recognized worldwide as a leading multidisciplinary expert in control, power electronics and power systems. Before joining Illinois Tech., he was the Chair Professor in Control and Systems Engineering at The University of Sheffield, UK, where he built up a $5M+ research lab dedicated to control of energy and power systems and attracted the support of Rolls-Royce, National Instruments, Texas Instruments, Siemens, ALSTOM, Chroma, Yokogawa, and other institutions. He (co-)authored three research monographs, including Control of Power Inverters in Renewable Energy and Smart Grid Integration (Wiley-IEEE Press, 2013). His fourth monograph, Power Electronics-enabled Autonomous Power Systems: Next Generation Smart Grids, is scheduled for publication by Wiley-IEEE Press. He proposed the architecture for the next-generation smart grids based on the synchronization mechanism of synchronous machines, which unifies the interface and interaction of numerous power system players with the grid. His current research focuses on advanced control theory, power electronics and their seamless integration to address fundamental challenges in energy and power systems.