Load Curtailment Teaches Ole Miss New Tricks

Load Curtailment Teaches Ole Miss New Tricks

When reducing costs and improving education share top priority, the University of Mississippi gives up a little reliability to gain some Like many schools, the University of Mississippi in Oxford, Miss., is always interested in maintaining its quality of education without increasing costs. The university wanted to increase funds available for educational programs without raising fees, so when it learned

When reducing costs and improving education share top priority, the University of Mississippi gives up a little reliability to gain some

Like many schools, the University of Mississippi in Oxford, Miss., is always interested in maintaining its quality of education without increasing costs. The university wanted to increase funds available for educational programs without raising fees, so when it learned of a load curtailment initiative introduced by the Tennessee Valley Authority (TVA) that would allow it to reduce its electricity costs, it was eager to participate.

TVA's load curtailment plan is simple. In exchange for granting TVA the right to cut off its power during peak demand times for as many as 72 hr per year, UM has qualified for significantly reduced kilowatt and kilowatt-hour rates on its overall power usage. Darrell Russell, physical plant engineer at the university, says the reduced rates add up to more than $1 million in annual savings, cutting the school's electrical energy costs by 25% to 30%.

Load curtailment initiative details. The TVA, a power producer with a service region covering 80,000 sq mi, sells its power to 158 distributors and 62 large industrial and federal direct-serve customers.

TVA introduced the load curtailment plan to reduce its costs and better manage its resources. The plan allows TVA to curtail customer demand rather than invest in more generation facilities or pay higher market prices for excess power during peak demand periods.

The university qualified for the program because its overall electric load was more than 5,000kW and it was willing to make its entire electric load interruptible. The school also agreed to as little as one hour's notice before curtailment, although TVA tries to provide advanced notice whenever possible.

UM is the largest customer of the North East Mississippi Electric Power Association (NEMEPA), a distributor of TVA electricity. Because NEMEPA is a not-for-profit cooperative concerned only with keeping its revenue neutral, it was happy to help the school set up a load curtailment agreement. "While under this curtailment program, the university purchases its utility power at a reduced rate,” says Bob Collier, manager of NEMEPA. “This new rate causes a reduction in the revenue margin that NEMEPA previously collected from the university for its energy consumption. NEMEPA has been contracted by the university to manage the generation facility. NEMEPA also added a small facilities charge to the university's utility bill for equipment needed for the generation project, which helps keep our revenue neutral.”

Covering curtailment. The load curtailment plan helped the university save on its electric bills, but it created the new challenge of providing reliable power to the entire campus for those 72 hr a year when TVA could curtail its power supply. To that end, the school called in Fisher & Arnold, Inc., an architectural and engineering firm from Memphis, Tenn., to design, build, and oversee the construction of an on-campus generation facility.

For just less $7 million, the firm built the new facility to house 10 diesel generators with a maximum generation capacity of 20MW. The facility also has two empty bays that allow for future capacity growth to 24MW. Chet Puckett, project manager of energy services for Fisher & Arnold, Inc., says the new generation facility can power the entire campus for three or four days without refueling if necessary.

Information and system control. The system can function in the following three strategic modes:

  • "Island Mode" provides all the power necessary for the campus while the campus is completely offline from the utility.

  • "Baseload Mode" provides power supply in conjunction with the utility.

  • "Import/Export Mode" can provide power back to the utility's electrical grid.

A unique combination of equipment and technologies were used to provide the control and functionality necessary to operate the generators in these different modes. Each generator unit is equipped with its own control/monitoring system that allows for individual control and monitoring at the generator unit by an Advanced Power Technologies (APT) power module and switchgear.

An enterprise energy management (EEM) system from Power Measurement also contributes to the control within the facility. The EEM system comprises three meters located on a relay panel in the switchgear and a server PC that runs an EEM software package. Each meter fulfills a different function: one measures the overall load requirement of the campus, one monitors the power produced by the generators, and one tracks the incoming power from the utility at the service entrance of the university's substation.

"The meters are a small but key part in the system," Puckett says. "The information they provide allows the whole system to react quickly to any interruption in power from the utility, whether or not it is scheduled."

System information and control functions are available locally to users within the generation facility, as well as remotely to users with permission to either call in to the system's modem connection or log in via a virtual private network (VPN) Internet connection. Remote access permissions are held by staff at the university, NEMEPA, Fisher & Arnold, Inc., and Thompson Power, which is the Caterpillar distributor that supplied the generation equipment. Both local and dial-in access is monitored and controlled with three levels of physical and virtual security. For safety and control reasons, only the utility is authorized to dispatch the generators remotely.

The data collected by the meters is also used to confirm the data on the university's bills from TVA and to prepare operational reports for the system, particularly the operating costs of the generators. More specifically, data is drawn into a custom Excel-based decision model developed by Fisher & Arnold, Inc. The program, which is installed on the server PC, operates in the background to help determine the generators' operating costs on a real-time basis and limit the maximum price the university will pay for utility power at any given time.

Future revenue possibilities. The generation facility has excess capacity—as much as 8MW, depending on potential expansion and campus demand—that could be sold back to TVA or other entities when price conditions justify. When needed, UM and Fisher & Arnold will initiate the proper agreements with NEMEPA, TVA, and any other entities to allow power to be exported back to the grid and sold. Russell points out that all necessary protective, switchgear, and metering equipment is already in place. "The system is ready to go when the price is right," he says. "In fact, the entire 20MW of generated power has been exported back on to the grid on a test basis, to verify that the system functions properly."

As it turns out, the new system has offered an added benefit aside from lower utility costs. Prior to the construction of the generation facilities, UM didn’t have a full campus backup protection. With only small generators spotted throughout the campus for the most critical loads, the campus could be left in the dark after any loss of utility power. Now full power can be restored in less than a minute, as demonstrated not long after installation when a bird flew into the utility's transmission line system and dropped service to the university. The generators picked up the entire campus load in about 30 sec from the time of the outage, significantly reducing the effects on any functions or activities occurring at the institution. Not only is the new system saving the University of Mississippi more than $1 million a year, it has improved services for the entire campus as well. For Ole Miss, it truly is the best of both worlds.

Stieva is the lead writer for Power Measurement in Victoria, B.C.

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