Envisioning the Future Renewable and Resilient Energy Grids—A Power Grid Revolution Enabled by Renewables, Energy Storage, and Energy Electronics
Authors: Fang Z. Peng; Chen-Ching Liu; Yuan Li; Akshay Kumar Jain; Dmitri Vinnikov
Extended Abstract:
Today’s power grids are facing tremendous challenges because of the ever-increasing power demand, system complexity, infrastructure cost, knowledge base, and policy and regulatory issues to achieve supply–demand power balance and resiliency with respect to more frequent extreme weather events and cyberattacks. Many countries are calling for building up more transmission and distribution lines to increase power delivery capacities. This article is an attempt to answer two urgent questions: Is more transmission and distribution infrastructure really needed to meet the increasing power demand? What kind of future grid infrastructure should we envision and build? This article attempts to answer these questions and proposes the concept of community-centric asynchronous resilient energy grids. By clearly differentiating the concepts of grid resilience and reliability, the importance of building resilient power electronics’ devices and robust system-level control algorithms to achieve resilient grids is presented. To identify the shortcomings and propose advancements, power electronics’ technologies are categorized using the proposed concepts of natural source frequencies (NSf), energy storage, direct energy conversion/control and fault protection (DeCaFp), and high-efficiency energy consumption and buffering (heECaB) technology. The ability of networked microgrids to greatly reduce power outages and power system restoration time is demonstrated by leveraging robust decentralized and centralized control algorithms, identified through a comprehensive literature review. Future research areas are proposed to further enhance grid stability, controllability, cybersecurity, and protection against faults by leveraging the advanced capabilities of NSf, DeCaFp, and heECaB devices and system-level control algorithms.
Our proposed several fundamental and conceptual changes to today’s power grids would have wider implications than just for North America alone. From the enabling technology’s device level, one of the “fundamental and conceptual changes” is from “power electronics” to “energy electronics.” We define “energy electronics” as the integration— over both time or horizontal axis and functional or vertical axis—of power electronics with energy buffering functions, energy storage capabilities, and/or self-protection/circuit breaking, thus acting as an energy processing and delivery system. The proposed resilient energy grid can be built using a bottom-up approach starting from the community level and through the lens of energy instead of power to meet the need for both energy and resiliency with respect to natural and man-made disasters. Transforming today’s power grids to energy grids can significantly increase the energy delivery capacity of the existing transmission and distribution grid infrastructure to meet community energy demand. The NSf energy grids use the natural frequencies of inverter-based-resources and optimal voltage levels in the generation, transmission, distribution, storage, and consumption with much higher efficiency. Networked microgrids supported by fast acting centralized and decentralized control algorithms can be the building blocks of these future grids. The development of dynamic impedance-source control and protection schemes will be essential to protect the proposed grids from cyber and physical threats. Turning AC grids to resistive and active grids by making all passive and reactive grids equipment/devices virtually resistive and active will naturally increase (50-100%) the power delivering capability to their maximum capacity. Inverter-based resources, energy storage, and power electronics together can and will revolutionize the existing power grids and transform them into energy grids.
The implementation and theoretical expansion of these concepts are further detailed in two sequential papers published in Nature Scientific Reports. These follow-up works demonstrate how to implement impedance-source (Z-source) grids and re-define reactive power from both spatial and temporal physical meanings of energy exchange. By revealing the colossal interactions among all AC and DC sources and loads within a grid, these studies provide the roadmap for the revolutionary transition from traditional power systems to resilient, high-capacity energy grids.
