Exploring the Power of Wind and Solar in North American Electric Grids

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A reliable, clean, and cost-effective electric power grid requires effective use of a variety of energy sources, including renewables which offer dispersed, localized options close to where the electricity is consumed. To evaluate the impact of a high percentage of renewable energy in the electric supply mix, researchers at the University of Tennessee, Knoxville (UTK) have developed a variety of scenarios for wind and solar generation as well as supporting technology for enhanced communications, measurement, and cybersecurity. These efforts are sponsored by the Center for Ultra-Wide-Area Resilient Electric Energy Transmission Networks (CURENT), an NSF Engineering Research Center (ERC) supported by NSF and the U.S. Department of Energy and headquartered at UTK, with partner organizations including Northeastern University, Rensselaer Polytechnic Institute, and Tuskegee University.


CURENT's vision is a nation- or continent-wide transmission grid that is fully monitored and dynamically controlled in real-time for high efficiency, high reliability, low cost, better accommodation of renewable energy sources, full utilization of energy storage, and accommodation of responsive load. The UTK researchers used CURENT’s North American grid large testbed (LTB) platform to conduct rigorous, transparent, and replicable testing of wind and solar sources at 20%, 50% and 80% of the electricity supply mix. Among the specific questions addressed were their flexibility in meeting various loads, and energy storage on the future grid. The learned that further study was needed because high renewable penetrations yielded higher power fluctuations and lower grid stability. In the course of their research, they also developed hardware and software to study wide-area data streaming of voltage or current measurements, as well as a platform for studying cyberphysical events and evaluating the vulnerability of wide-area measurement-based control techniques. The latter serve as tools which allow researchers to identify approaches to enhance the security of the national transmission grid.


The overall objective of CURENT’s LTB is to represent large power grids of the future at several resolution levels for both evaluation of new technologies and to help direct further research efforts. In the testbed, computer models simulate different scenarios of generation fuel mix and operation, wide-area measurements, new actuation technologies, and new control strategies. CURENT’s LTB uses integrated data from three major U.S. power transmission grid models: The Eastern Interconnected (EI) System—from the Atlantic Ocean to the Rocky Mountain states; the Western Interconnected System—managed by the Western Electricity Coordinating Council (WECC) for states west of the Rocky Mountains; and, the Texas Interconnected System—managed by the Electricity Reliability Council of Texas (ERCOT). The LTB strives to mimic the structure and operation of a real power system. CURENT developed the LTB to serve as a real-time grid operation platform to continuously simulate the operation of an actual power grid with small or large disturbances using communication and control actions as considered under wide- area measurement. While the traditional power system simulators only focus on the physical power system components, the LTB incorporates power system components, communication networks, energy management systems (EMS) and a measurement-based control system into an integrated platform for researchers to address emerging challenges such as renewable energy integration and cyber-physical security under innovative measurement-based technologies and controls.