Warm weather and multiple entertainment venues draw more events and visitors each year, requiring the Orange County Convention Center in Orlando, FL, to constantly expand. The latest Phase-V expansion project consists of 2.8 million square feet of exhibit and meeting space, making it the largest public project in Orange County history. Combined with the other four phases, the total complex is now the second largest convention center in the US. To make sure that the new addition had a reliable supply of standby power for lighting, security, and life-safety systems, the general contractor, Hunt Construction Group, turned to Cummins Southeastern Power for an “unconventional” solution.

The Phase-V building is an entirely separate structure with its own standby power system. Other phases of the sprawling convention center have their own standby power systems, too, but this newest standby power system is unconventional in several ways, according to Mike Sincavage, electrical manager for Hunt Construction. The most unusual aspect is that the standby power system is located in a separate building approximately .5 mile from the Phase-V building. The generators are connected by a high-voltage, underground power line (15 kV) to minimize line losses; and communication with the 72 automatic transfer switches is carried out over a fiber-optic cable system. The power system’s PowerCommand Digital Master Control also communicates with the facility’s building management system (BMS) for various operations and maintenance functions.

Backup for Lighting, Life-Safety Systems
The standby power system in the Phase-V expansion consists of four 1,500-kW PowerCommand diesel generator sets from Cummins Power Generation, along with associated controls, switchgear, and automatic transfer switches. The 6-MW standby power system is designed to provide backup power for all the lighting in the complex, the ventilation fans, refrigeration in the four food-service courts, elevators, and security systems in the event of a utility power failure. This would allow visitors to safely exit the building from the main show floor and upper galleries; maintain basic security systems; and prevent food spoilage in the event of a prolonged outage.

The remote power building houses four 1500-kW standby generator sets from Cummins Power Generation.

Approximately 6 MW of standby power is available within 8 seconds of a utility power failure.

The new standby power system is one of several layers of power redundancy built into the new Phase-V facility. With 11 separate feeds from the Orlando Utility Commission for a total connected load of 36 MW, it would seem that the complex is well protected from utility outages. But, according to Sincavage, “Orlando is the lightning capital of North America, and momentary outages are common.” What’s more, hurricanes and tropical storms are also common and capable of widespread devastation that affects multiple utilities, substations, and power lines. The standby power system was required to ensure the utmost in power reliability and the safety of tens of thousands of convention visitors.”

2004’s Hurricane Charley Tests System
“The building was not hosting a show when the eye of Hurricane Charley passed directly over Orlando and knocked out a significant amount of power in the area. Although some buildings in the convention complex did not lose power, the Phase-V complex did, and the new standby power system came on and operated as designed for several hours,” says Brian Kennedy, assistant HVAC supervisor of the Orange County Convention Center. “Anytime the automatic transfer switches sense a power loss from any of the 11 utility feeds, they send a signal to start the generators.”

When a power outage occurs, all four 1,500-kW generators start and come up to operating speed in about eight seconds. The first generator to reach speed and proper frequency closes with the main bus. If one or two generators are sufficient to carry the emergency load, the other two generators shut down automatically and return to a standby mode. When normal utility power is restored, a signal from the automatic transfer switches sends the generators into a “cool-down” mode before shutting them down. With 10,000 gallons of diesel fuel on hand, there is enough fuel to power all four generators for 24 hours. With the current level of standby power demand at only about 2 MW, there would be sufficient fuel for about three days, says Kennedy.

“The whole standby system is automatic,” Kennedy continues. “Plus, it is designed to ‘fail-on’—meaning that even if the fiber-optic communication network fails, the generators will start and be available for power.”

Oversized for Reliability, Growth
With a current emergency load on the generators of only about 2 MW, the 6-MW standby system is significantly oversized. Citing that as a “good thing,” Kennedy says that the larger system provides enhanced reliability in the event that one of the four generators fails to start, or one of the units is down for scheduled maintenance. The larger system also provides capacity for growth as the facility expands or as other critical loads are identified. The off-site power building was designed to house an additional 6 MW of generation (for a total of 12 MW) should that be necessary for future growth.

According to Sincavage, the four 1,500-kW generators provided more generating capacity in a smaller footprint than a previous design involving six 1,000-kW generators. “Not only did the Cummins generators provide more capacity in a smaller footprint, but we liked the fact that the generators, transfer switches, and digital controls were all pre-integrated and came from a single source,” he says. “With the PowerCommand digital controls built right into the generators, it simplified a number of control and communications issues.”

Building Management System Integration
A major advantage of the PowerCommand digital control system is its ability to interface with building automation and management systems. This provides system operators with a continual, functional remote view of the standby power system and how it relates to the rest of the systems in the building complex.

“The standby power system is tied directly into our Johnson Controls BMS,” explains Kennedy. “We have it set up so that whenever the generators start, the BMS issues an alarm condition that tells us that the generators are running and available for power. It also provides us with information on coolant temperatures, fuel levels, and other diagnostics without having to go to the power building. All this can be supervised from our central energy control center across the street, which is manned 24/7.”

The BMS can also control the priority of certain loads and decide which loads need to be shed if there is not enough standby generating capacity available. “The BMS can analyze how much capacity is available and shut down some ventilation fans or refrigeration if needed,” says Sincavage. “The BMS is also helpful from a maintenance standpoint. System diagnostics can be performed and historic reports generated, in addition to other maintenance procedures that enhance reliability.”

To further enhance reliability, Kennedy says they have a two-year maintenance agreement with the local Cummins distributor to perform all required maintenance on the standby power system. Experience has shown that regular maintenance is the most important factor in power-system reliability.

The Orange County Convention Center will no doubt continue to grow as a leading convention destination for organizations and industries all over the world. The thousands that will attend events at the new Phase-V facility can take comfort in the knowledge that an “unconventional” standby power system is adding to the certainty that they’ll have a great convention experience.

BOB SHELDON is public relations director for Creative Communications Consultants, in Minneapolis, MN.

DE - November/December 2005