Electric Transmission 103: Upgrading the Grid

This briefing is the third in a series co-sponsored by EESI and WIRES. The other briefings were "How the Grid Works", "Policy Challenges to Grid Expansion", "Cost Allocation", "Integrating Variable Renewable Resources" and "Planning to Expand and Upgrade the Grid" .

On June 4, the Environmental and Energy Study Institute (EESI) and WIRES (Working group for Investment in Reliable and Economic electric Systems) held a briefing to discuss the upgrade and expansion of the nation's electric transmission systems. The use of digital technologies, advanced materials, communications, and system innovations can and are transforming the transmission system into a highly integrated, vital, and efficient network for a truly 21st century bulk power market. This briefing explored new and emerging technologies being deployed as part of the high voltage grid to enhance its capacity to transfer power, efficiently handle dispatch of system assets, ensure reliability, integrate variable renewable energy generation, and make the grid more efficient. This briefing also helped advance an understanding of the grid's operational capabilities and related investment opportunities and how they are changing.

• The concept of a “smart grid” lacks a standard definition but centers on the use of advanced technology to increase the reliability and efficiency of the electric grid, from generation to transmission to distribution. However, the smart grid does not necessarily replace the existing infrastructure, most of which was installed in the 1970’s.
• Some of the most common themes in a smart grid include advances in technology such as ubiquitous two-way communication, advanced sensors, and distributed computing. A smart grid would increase connectivity, renewable energy integration, distributed generation, and efficiency in demand response, consumer savings and reduced emissions.
• The term “smart grid” does not necessarily imply that the current grid is “dumb,” but it does indicate that there are several opportunities to improve the equipment and technology that make up the electrical grid as the United States shifts towards a more diverse and distributed energy supply.
• The electric transmission grid can be considered America’s “largest machine,” meaning that an event in one section of the grid can have an effect a thousand miles away. The 2003 blackout in the Northeast caused $7-10 billion in economic loss, and the advanced technology of a smart grid seeks to address potential problems by providing immediate feedback and distributing power more intelligently.
• SynchroPhasors are microprocessor-based measurement systems that give real-time data about power flow on the grid, acting like “the electrical equivalent of a tsunami warning system.” This technology and other advanced monitoring systems already exist, and there are 40 (Synchro)Phasor Measurement Units (PMUs) currently installed in the eastern power grid.
• Alternating current (AC) functions best at short distances and makes up 95 percent of the U.S. grid. Direct current (DC) is more cost effective for long distances.
• In a new application of an existing technology, superconductor power lines carrying DC current are 150 times more power dense than conventional lines, which results in higher efficiency and smaller footprint. They use 24 times less land because and can be installed underground along existing infrastructure, such as roadways or railroad lines. They are currently used in the demonstration phase in Long Island.
• High Voltage Direct Current (HVDC) technology uses special substations to convert AC to DC current for transmission of large amounts of electricity over long distances or under water. Currently, there are four lines in North America, with a more coordinated plan being developed across the Midwest and East Coast. HVDC lines can complement a well-designed AC network.