Report: New Line Technology Boosts Reliability, Reduces Costs

  • Gives dispatchers better real-time insights into transmission lines, improving reliability and reducing costs
  • PJM partners with U.S. Department of Energy, American Electric Power and LineVision on pilot program
  • Paper on pilot program wins international award

PJM always looks for ways to embrace innovation and collaborate with its members and other key players in the industry to explore new and emerging technologies.

One such new technology is a new dynamic line rating tool, which reports the real-time ampere capacity capabilities of thermally limited transmission assets.

This equipment monitors and reports on transmission line temperature (and therefore, congestion) in real time. This potentially gives dispatchers a more accurate understanding of a line’s capacity at any given moment, expanding its capability, improving reliability and resulting in cost savings as well.

“We knew about the concept, it was a question of getting in contact with someone about the specific technology,” said Shaun Murphy, senior engineer – Market Services, who worked on the project with Nicolae Dumitriu, senior lead engineer – Market Simulation.

Collaborative Effort

PJM collaborated on a pilot program for the new tool with American Electric Power (AEP) and LineVision (formerly Genscape, Inc.). The pilot was performed on the Cook-Olive 345 kV transmission line between Michigan and Indiana in the AEP transmission grid.

The U.S. Department of Energy, through the Oak Ridge National Laboratory, coordinated the project, brought the players together and provided funding for the effort.

To determine a line’s dynamic limit, measurement equipment is installed in the transmission right-of-way to monitor the real-time conductor temperature as it changes with weather and loading conditions. This pilot successfully demonstrated that dynamic line rating, or DLR, can provide additional capacity and overall variability on a typical overhead transmission line.

“The results show the great potential for DLR systems to act as a tool for better congestion management,” said Murphy. These systems also provide increased situational awareness of the grid.

Another benefit of DLR systems is that they can be retrofitted to existing transmission lines. “They could be rapidly deployed to provide needed capacity to bridge the gap between the proposal of a Regional Transmission Expansion Plan or a market efficiency project and that project being put into service,” Murphy said.

Economic Impact

To better understand the overall economic impact, PJM performed economic analysis of a hypothetical DLR installation on one of the most congested lines in its footprint, dubbed the Target Line.

Currently, the DLR technology is used more internationally than domestically. While there is research going on in other areas of the country, the PJM pilot is the only one in the United States to simulate the economic impact.

Using historic National Oceanic and Atmospheric Administration weather data, LineVision generated back-casted hourly DLRs for the Target Line path. PJM used the data as ratings in a PROMOD Market Efficiency base case software simulation and then compared the simulation results to a base case simulation using standard summer and winter static line ratings. PROMOD is the tool PJM uses for fundamental electric market simulations.

Eliminating ambient weather assumptions (as per static line ratings) and switching to DLR (based on measured line parameters) alleviates the reliability and safety risks associated with times when a line’s static rating may not be conservative enough.

Line monitoring data revealed significant additional current capacity on monitored lines with similar results expected for all lines in similar geographic areas.

The analysis showed that use of DLR equipment would have reduced congestion payments by more than $4 million over the course of one year.

Boosting Reliability

In addition to the economic benefits, incorporating these types of advanced transmission technologies provides greater real-time situational awareness of the grid, which increases system resilience.

“Currently we don’t know the true conductor temperature, so without any measurement devices, we make a conservative assumption,” said Murphy. “This is to ensure reliability first, but we know that sometimes, it can be overly conservative.

“We know, at any given time – no matter what the wind or sun is doing – that we could overestimate the temperature to control the flow on the line, so we don’t risk damaging it. But, if we can replace our assumptions with a temperature measurement, we can ensure reliability and reduce congestion costs. That’s what the economic analysis showed us.”

The pilot will provide transmission companies additional information on the potential of DLR as they plan future transmission investments.