Some of these needed improvements will require little in the way of new or advanced technologies, but they will depend more on policy decisions and implementation. For example, improvements in regulations, the training of participants in the market, and significant capital investments are all important.


Power outages can cause significant financial losses for U.S. industrial and commercial customers, as much as $80–100 billion annually, and can be very inconvenient or even dangerous for people. As discussed in the main text of this chapter, the 2003 blackout in the North American Eastern Interconnection occurred because a small problem in one part of the system resulted in cascading failures throughout the system. A self-healing transmission system could minimize such occurrences.

Self-healing actions are defined as automatic responses by the system such that system collapse will not occur and that, at worst, “graceful degradation”—which involves minimal interruption of service—will result. For example, faulty equipment or lines can be isolated when necessary to prevent problems from spreading. A self-healing system should be capable of being restored to normal operation with little or no human intervention. This means that both the transmission and the distribution system will have the ability to sense the state of the system as well as communicate this information to other parts of the system and take appropriate action. A wide variety of new measures will need to be implemented to create a self-healing T&D system. Many of these measures will be technological, while others will involve the development of software and standards. For example, research and development (R&D) is still needed on many of the algorithms involved (J. Eto, personal communication, 2008). In addition, integrating the new technologies will be a major challenge.

For transmission, the needed measures include: effective and advanced monitoring; methods for very quickly determining the cause and location of a fault or instability; probability-based contingency analysis; rapid system alignment for the next contingency; effective use of flexible alternating current transmission system (FACTS) devices and HVDC to stabilize system voltages and power flows; remotely dispatchable storage near generators and load centers; effective use of customer-generated power and storage; intelligent load-shedding; effective islanding; fast restoration means; strict reliability standards; and predictive maintenance of key components (NETL, 2007b). Many of these approaches are described in the sections that follow.

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