Aggreko supplies 60 MW of power to ComEd; GreenPower gen-sets utilize Cummins diesels, Newage alternators

The summer of 1998 brought with it an acute power shortage that adversely affected the upper Midwest. As a result, Commonwealth Edison (ComEd), the major utility based in Chicago, contracted with several companies to supply diesel generator sets to supplement the power grid. One of those companies was Aggreko, New Iberia, La., which provided 20 MW of temporary diesel driven power generation.

The project was deemed such a success by ComEd that in the spring of 1999, Aggreko was again called on to augment the utility power, this time supplying 60 MW for distributed generation.

"We were extremely pleased at the return business," commented Mark Stavrakis, Aggreko project manager. "Aggreko pioneered the seasonal peak shaving application in the utility market by using temporary diesel generators. Our teamwork efforts were most instrumental in our success last year here in Chicago, and with the scale of the project increasing considerably this year, it has played an even more vital role."

Two Chicago area substations were supplied with two dozen 1250 kW generators totaling 30 MW each. "Because our equipment is designed to be easily installed and operated together, each site was installed and running in less than two weeks," noted Stavrakis.

A group of seven Aggreko employees, including technicians and market specialists were brought in from as far as Corpus Christi, Texas, for the nearly month-long installation process. The sites are manned by Aggreko technicians throughout the duration of the project with crew change-outs taking place every 30 days. "The units are maintained and operated by Aggreko personnel starting each unit individually and manually paralleling to the grid," said Stavrakis. "In other applications, these generators could be controlled and operated from a central control room or remotely."

Aggreko is using its standard GreenPower generator sets, which are powered by Cummins KTA50G3 diesel engines driving Newage 1875 kVA synchronous alternators producing 480 V, three-phase a.c. power. Each generator utilizes a VAR/power factor controller to maintain the proper power factor.

In operation, each generator first synchronizes with the grid and is base loaded to 1000 kW. The generators are typically being used six to eight hours a day as needed, based on area grid demands.

The generators are set up in groups of two and are connected to one 2500 kVA transformer to increase the voltage to 12,470 V. "There are 30 transformers on this project and they are all designed with the same specifications to be compatible with other," said Stavrakis. "This is extremely important in a parallel situation."

The 2300-gal. Aggreko EnviroTank fuel tank allows for approximately 15 hours of continuous running. "These tanks are an Aggreko design, incorporating double wall construction to insure a leak-proof, environmentally favorable application," said Stavrakis. "To further insure there will not be any fuel or oil leaks, the generator containers are designed like a bathtub in order to hold all of the internal fluids in the event of a leak."

More than 24,000 ft. of low voltage cable was used for the massive setup. The project was scheduled to run throughout the summer and will be demobilized this month.