by Bob Shively, Enerdynamics President

In our latest blog post, What Is the Smart Grid?, we discussed three applications for the Smart Grid. One such Smart Grid application is performing the functions that transmission owners and distribution utilities do today but simply using new technology to do it more efficiently and reliably.  This post elaborates on this application by providing an example of how implementation of Smart Grid technologies can improve reliability and asset utilization for an electric transmission company.

Traditionally, system schedulers used models to estimate the capacity available on transmission lines given expected weather, system flow, and other factors.  Using estimated data and modeled conditions forced operators to be conservative since they had to be careful not to exceed physical line limits.  This means the true physical capability of lines often was underutilized.  By installing and utilizing technologies that allow real-time monitoring and visualization of line conditions, operators can more fully use the capability of existing transmission lines.

So what technologies allow real-time monitoring?  These include monitoring devices that allow views into the condition of the power flowing on transmission lines as well as physical monitoring for factors such as line tension, line temperatures, and line sagging.  This could be as simple as video cameras on top of towers that allow real-time visual monitoring for sag or may be as advanced as widespread installation of phasor measurement units (also known as PMUs).

PMUs allow visualization and monitoring of the magnitude and phase angle of system voltages and currents.  Coupled with analytical software, this data allows operators to analyze voltage, current, reactive power, and frequency at multiple locations throughout the grid.  Given this knowledge, they can determine exactly what can and cannot be done on the transmission grid based on actual conditions. Thus, they can often identify problems before they occur and proactively solve the issue.

For a good discussion of how PMUs have helped one transmission owner, Southern California Edison, see the article “Phasors Point the Way” on tdworld.com.