NPPD takes actions to ease burdens on its system during hot summer

The Nebraska Public Power District (NPPD) is taking steps to take some of the pressure off its transmission system from summer demand that is expected to rival the record demand seen during the summer of 2012.

The agency set a peak demand of 3,030 MW on July 25, 2012, and, while NPPD had adequate generation resources, “Our transmission system was overloaded last summer,” an NPPD spokesperson told TransmissionHub on March 20.

Last summer, NPPD saw high demand due to increased use of air conditioning, and crop irrigation due to a lack of rainfall and overall drought conditions. In limited cases, curtailment was needed to avoid overloading the transmission lines and maintain the reliability of the system, NPPD officials said. Conditions are expected to be similar this year, according to a forecast given to NPPD’s board of directors on March 15 by the state’s climatologist.

“Nebraska relies heavily on irrigation, and the ground is dry,” the spokesperson said, adding, “There’s a lack of moisture coming out of the mountains, there’s not much of a snowpack, [and] they’re not anticipating much moisture over the next few months.”

As a result of those dry conditions, the agency is bracing for increased demand as early as April, when the region’s farmers are expected to turn to irrigation, which often uses electrically driven pumps, to water their crops.

Although NPPD has a load-control program in place that allows it control over approximately half of its 1,200 MW of the demand attributable to irrigation pumps, it’s not enough, officials say.

To reinforce its system, the agency will install five, 8-MW mobile diesel generators at substations in its Zone 5, which covers a large swath of central Nebraska. The generators will reduce the burden on parts of the area’s transmission system by adding generation closer to load.

The generators, which the agency is leasing from Cummins Central Power in Omaha, Neb., will arrive on June 1 and be ready to operate no later than June 15. The cost of renting, installing, and removing the generating units and the fuel to operate them is estimated at $4.7m to $7.9m.

In addition to the 40 MW of new, distributed generation, NPPD has been upgrading portions of its transmission system. Improvements include reconductoring a critical transmission line between its Battle Creek and North Norfolk substations. That project is expected to be completed by the end of March, while additional upgrades are expected to be completed before mid-June.

NPPD’s proposed 345-kV Hoskins to Neligh transmission project, which will run from Hoskins, Neb., about 70 miles southwest of Sioux City, Iowa, to Neligh, Neb., about 47 miles to the west, will provide a significant improvement to the transmission system and provide longer-term support for Zone 5. However, that line is not expected to be in operation until June 2016.