Dynamic Thermal Circuit Rating Technology

Dynamic thermal circuit rating (DTCR) technology can be used to increase the thermal loading on individual transmission lines. Present limits are both static and often conservative, based on assumed weather conditions. DTCR uses real-time information about weather, load, temperature, line tension, and/or line sag to estimate actual thermal limits, allowing higher thermal capacity of lines. Certain DTCR devices are commercially available, and others are currently being demonstrated on a few transmission systems.

Video Sag Monitoring

Direct monitoring of line sag can be used to extend the effectiveness of DTCR even further. A video “sag” meter has been prototyped that uses a digital camera mounted on a transmission tower to monitor the vertical position of the line. Sag monitoring is listed separately here and not included under the broader title of remote video monitoring of critical components because it enables dynamic operation.

Topology Estimators

Topology estimators can be used to accurately determine the real-time transmission grid configuration status of an interconnection. Accurate information on topology is necessary for accurate state estimation and the subsequent security-constrained dispatch that is the key computation for solving congestion problems.

Improved Simulation and Modeling

Faster-than-real-time simulation and improved modeling would enable very rapid computation of the power condition’s status, and in turn:

•   Faster-than-real-time, look-ahead simulations of operating conditions;

•   What-if analyses from both the operations and the planning points of view;

•   Integration of risk analysis into system models and quantification of effects on system security; and

•   Through the use of advanced simulation, pattern recognition, and diagnostic models, determination of the location and nature of suspicious events.

Monitoring of Constraints

Sensor output, communication, and computation can be used in combination to monitor the effect of transmission constraints on wholesale power market activities. Operating in a limited fashion for the Eastern Interconnection, this capability could be enhanced to include probabilities of line outages on which a probabilistic reliability index could be based.

Database Protocols Development

A common information model is needed for transmission and distribution operations and maintenance databases. It would support interoperability by greatly reducing the number of needed software translators in situations involving a range of applications.

Technologies That Enable Increased Asset Utilization

Growth in the demand for electric power in dense urban areas will continue to challenge the capacity of the traditional medium-voltage underground network grids installed in most large cities to provide reliable power. To meet projected increases in demand while still providing safe, reliable, and affordable power, utilities will have to reconfigure networks and minimize secondary (low-voltage) cable. Technology options include the following:

Submersible (Underwater) Fast Switches

Fast switches enable connection of customers to alternate power sources during system reconfiguration, and a capability for reconfiguration at medium voltage minimizes the impact of a catastrophic event at a single power station or circuit. In underground networks where flooding is possible, there is a need for switches that can operate underwater while still energized so as to mitigate outages.

Low-voltage Switches and Smart Fuses for Isolation

Low-voltage devices such as automated breakers (switches) and smart fuses that respond to appropriate rise times allow for reconfiguration and isolation of faulty sections of the low-voltage grid network.

Technologies That Are Particularly Intended to Enhance Security

The technologies discussed in this chapter will contribute to enhanced security of the electric power system even though that is often not their primary goal. Technologies specifically intended to improve security will, in most cases, provide significant benefits in the face of major equipment failures resulting from natural disasters as well as terrorist attacks.

Probabilistic Vulnerability Assessment

A key priority among efforts to improve overall system security is to assess power system vulnerabilities to terrorism and identify the most effective countermeasures. Probabilis-



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