New System can Monitor Large Power Systems

Wednesday, January 19, 2011 @ 05:01 PM gHale


There is now a new system in development that is capable of monitoring large power systems in an effort to avoid major power outages like the one that hit the Northeast in 2003.

By using high-resolution power-system measurements, called Synchrophasors, researchers can monitor large power systems and aid in the development of newer, more reliable power systems, said Dr. Aranya Chakrabortty, study leader and assistant professor of electrical and computer engineering at North Carolina State University, along with co-authors from Rensselaer Polytechnic Institute and Southern California Edison.

This system could alleviate major power outages that can cost upwards of billions of dollars.

The 2003 Northeast Blackout, which cut power to approximately 50 million people, resulted in $4 to $10 billion in costs and multiple fatalities. What led to this major power outage was the fact there was a “significant” disparity when it came to reactive power between the Midwest and New England, despite generating units appearing to work fine. This disparity caused a series of voltage collapses leading to the blackout. This showed the system needed a global monitor instead of having individual nodes “in isolation.”

“We need to have a better understanding of how a disturbance entering one generation cluster — or localized group of nodes — may spread across the system, creating havoc in its neighboring clusters as well,” said Chakrabortty. “More importantly, we need to investigate if the speed of this spread is dictated by the way these clusters are connected to each other.”

In an attempt to prevent this from happening again, Chakrabortty and his team of researchers used Synchrophasors to keep an eye on large power systems. Synchrophasors are real-time measurements of currents and voltages that offer a high-resolution view of the events occurring within a large power system. Phasor measurement units (PMUs) are the digital recording devices that measure Synchrophasors.

“PMUs are comparable to surveillance cameras that continuously monitor the complex dynamics of groups of people in busy places, and indicate how different people respond and interact with each other,” said Chakrabortty.

Chakrabortty and his team have made a plan to use Synchrophasers from PMUs to create cluster models, where the Synchrophasers from PMUs go at different points within a cluster of nodes. Researchers can compare the PMU measurements at the different points in this system in order to understand how the clusters connect to one another.

“Once you have modeled the clusters and determined their connections, our algorithm enables you to model the interactive behavior of the clusters within the larger system in the face of large disturbances,” said Chakrabortty. “We also show how to place PMUs optimally at the nodes so as to extract maximum amount of useful information for better modeling.

“Our models are informative, yet easy to compute. They will help power system operators track and predict the global health of any distributed power system in real-time so that catastrophes such as the 2003 blackout can be prevented in the future. The study will lead to an entirely new vision of monitoring and controlling the North American grid, which is becoming more expensive and more chaotic day by day.”



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