In the midst of the California energy crisis, it's no surprise that more large power users are rethinking their power usage needs and patterns.



To West Group, a leading provider of electronic information and solutions to the United States legal market, few things are more important than quality power. “Our business runs on electricity,” explained Tom Walrath, senior director of facilities management at West Group. So when West Group prepared to install a new power generation facility on its 300-acre campus in Eagan, Minn., it set out to design and build a world-class facility. The result is one of the largest corporate-campus distributed-generation systems in the world.

In the midst of the California energy crisis, it's no surprise that more large power users are rethinking their power usage needs and patterns.

That certainly was the impetus for West Group, which operates a computer-assisted legal research service known as Westlaw, to take on this project. With attorneys needing to tap into legal information 24 hours a day from anywhere in the world, Walrath characterizes the project's power requirements as “zero tolerance for downtime.”

With its mission-critical energy needs in mind, West Group embarked on a two-year, $5.5 million project in 1997. Its goal was to install the most reliable distributed power system it could find. The 14MW West Group facility represents the largest single-site generation installation undertaken by the turnkey installation firm Energy Alternatives to date.

Meeting Project Requirements

Although power redundancy was a primary requirement, there were other key factors, including the ability to peak shave and sell power back to the grid. West Group also wanted to receive cost savings from the local co-op utility (Dakota Electric Association), which services the Eagan area and the facility's 5,400 employees.

Dakota Electric offers its customers an “interruptible rate” on their power. This means West Group receives a reduced rate on its power throughout the year as long as the utility can “pull the plug” on campus power for as long as a peak demand exists.

Walrath said the rate savings should provide an approximate four-year return on investment and an excess of $1 million annual electric bill savings.

Energy Alternatives' first step was working with building engineers to design a sound-sensitive 7,620-sq-ft building that would eventually house seven 2MW generators, supplied by Caterpillar. In addition, West Group had to calm the “not in my backyard,” concerns in the neighborhood over the installation of the equipment.

“The community knew that whatever we were going to do, we were going to do right,” Walrath said. “We are located 500 yards from a residential area. We have been in this location for 25 years, and we have an excellent relationship with the community. They trust us.”

Minimizing Noise

West Group's power generation facility is located next to the local substation on the perimeter of the campus. This strategic site helps the company save on feeder installation costs. Noise, however, was still a concern. To achieve a sound-minimizing structural design, Energy Alternatives hired a sound engineer to ensure the generators did not exceed a preset decibel level of 55 dBA.

Custom pads — each a different depth and shape — were installed under each gen-set so that each unit would emit a different frequency. When the frequencies of each generator emit randomly, they do not multiply and may cancel each other out. Technicians tuned the generator's exhaust pipes for minimal decibel output and installed 7 ft of sound attenuation on the facility's residential side.

When operating, the sound level in the engine room is 120 dB, which is comparable to the sound level of a jet engine at full throttle. Outside the facility, the sound level does not reach more than 55 dBA at the property line.

Ensuring Power Flow

With smaller engine gen-set installations, there is typically one generator per transformer. Not here.

The seven generators are aggregated through ASCO Power Technologies' switchgear to provide 12.8MW of prime power or 14MW in standby mode. This is roughly enough power to supply 4,000 large homes. The power is then sent to a single transformer that resides on the Dakota Electric side of the fence.

Different codes applied to each side of the substation fence increased the amount of engineering required on the project. The National Electric Code (NEC) applies to the customer side, while the National Electrical Safety Code (NESC) applies to the utility side.

The custom switchgear arrangement makes all modes of power transfer possible. The switchgear comprises nine sections holding seven 5000V generator breakers, one 5000V main breaker, and one utility tie-in section where a bus duct connects the switchgear to the step-up transformer. The switchgear has four modes of operation: export, demand, isolate, and standby.

Two separate substations that rely on an automatic switching configuration serve West Group. If one substation or transmission line fails, the other automatically takes over. If both of those power sources fail, the generators automatically start to pick up the load and isolate the campus from the rest of the utility system.

Total time to complete gen-set backup after a severe outage is two minutes, which includes time delays for substation switching. During that time, uninterruptible power supply (UPS) systems and other small gen-sets power West Group's lighting and critical loads. All the switchgear equipment has a battery backup system for operation during a power outage.

Conclusion

Since the project's completion in 1999, Walrath said the system has been periodically put through its paces. It is typically in operation for peak shaving during the summer months, but in 2000, the system was run in the winter months in response to increased demand placed on the grid by community homes during the holiday season.

“I think the concept of distributed power is a great use of equipment,” Walrath said. Apparently, many others think so as well.

For the past year and a half, engineers, hospital administrators, city administrators, and data center operations managers from around the country have bombarded West Group with requests for visits. Groups have even flown in from overseas to tour the facility and obtain more information on the setup.