August 10, 2006
[Article on Entergy Intranet]
What’s a PMU? Why Does Entergy Have 15 of Them?
The August 2003 blackout, largest in US history, did not directly affect Entergy’s customers. But since then, Entergy has played a leading role in a program to improve power system reliability, not only within our service territory, but across the entire Eastern Interconnect.
Entergy Transmission engineers, along with other utilities and various public and private agencies, have developed and are now testing new monitoring devices that provide near-instantaneous measurement of the Eastern Interconnect’s dynamic function.
The official report on the blackout concluded that faulty grid monitoring, and operators’ lack of awareness of deteriorating conditions, played large roles in the massive blackout.
Need to Know to Prevent Problems
The blackout showed the need for real-time, wide-area visibility, situational awareness and monitoring tools across the interconnected transmission systems serving the Eastern U.S.
In October 2003 the Department of Energy brought together utilities, vendors, and universities to look for new ways to mitigate the effects of system disturbances. This group became the nucleus of the Eastern Interconnect Phasor Project.
Entergy, TVA, NYPA, and AEP are the founding utilities. Almost three years later, EIPP has over 100 utility and non-utility participants.
Entergy’s Phasor Measurement Units
The Entergy Phasor Project reached a project milestone in July with the operation of the first of two new EIPP servers at the SOC in Pine Bluff. These servers will drive new operator screens that can be configured based on input from the operators.
Although the blackout did not affect Entergy’s transmission system, when it happened, like most utilities in the Eastern Interconnect, Entergy did not have any PMUs on its transmission system.
Today 15 PMUs are strategically sited within our service territory. Entergy maintains one of the newest and largest PMU systems in the Eastern Interconnect. The PMUs, spread across our four state territory, are recording data on our 115KV/138KV, 230 KV, and 500 KV transmission lines.
What Does a PMU Do?
“The Entergy Phasor system reflects the most current, most accurate understanding of transmission system dynamics. It is a reality thanks to the efforts and hard work of the Entergy Phasor Project Team,” Floyd Galvan, Entergy-EIPP Project Lead.
In addition to Galvan, Entergy’s EIPP team includes: Ian Barras, assistant project manager; Sujit Mandal, planning & phasor applications; Leonard Chamberlain, communications infrastructure architect; Steve Winsett, Pi applications and visualization; Jim Varnado, field installation construction & maintenance; Jerry Berndsen, communications & testing; Ryan Prejean, Entergy real-time operations.
Entergy’s EIPP team is lead by executive sponsor, Randy Helmick, vice president-transmission.
The knowledge this effort gives will be used to develop better transmission operating procedures and reinforcement plans. That means a more stable, reliable system serving our customers.
A key lesson from the August 2003 blackout was the need for time-synchronized system data recorders. Without these, it is time consuming and laborious to reconstruct the events that together lead to a wide spread blackout.
Another value of PMUs is that since they are time synchronized, and have a high sampling rate, they can measure between two buses, thereby improving the ability to monitor grid dynamics and stability for reliability management. This was never possible before. Together, these benefits will be significant steps in enhancing the reliability of Entergy’s transmission system and of the entire Eastern Interconnect.
In three years the EIPP Task Teams have taken the Eastern Interconnect from a system with no wide area measure to one with more than 75 planned or implemented PMUs.
Entergy’s PMU Sites
Six PMUs are in Arkansas, four in Louisiana, three in Mississippi and two in Texas. Entergy’s 15 PMUs are placed where they can monitor important interfaces and areas of the Entergy system where disturbances can cause problems.
You’ll hear more about EIPP as it evolves into the North American Phasor Project (NAPP). The EIPP website gives you up-to-date information on EIPP: http://phasors.pnl.gov/