How to engineer manufacturing, industrial buildings: Electrical and power systems
- C. Erik Larson, PE, LEED AP BD+C, Principal, Industrial Systems, Wood Harbinger, Bellevue, Wash.
- Ronald R. Regan, PE, Principal, Triad Consulting Engineers, Morris Plains, N.J.
- John Schlagetter, NCARB, PMP, CSI, CCS, CCCA, LEED Green Associate, Senior Architect, Process Plus, Cincinnati
- Wallace Sims, SET, NICET Fire Alarm Level IV, Lead Life Safety Engineer, CH2M Hill, Portland, Ore.
CSE: Describe some recent electrical/power system challenges you encountered when designing a new building or working in an existing building.
Regan: A client acquired an existing 20-story high-rise with the intent of duplicating an existing data center environment he has in another state with more than 250,000 sq ft of white space. The building’s power system, while extensive and capable, was no match for the anticipated load. Compounding the fact was that the facility sits on the Hudson River and was a victim of Hurricane Sandy flooding. The first issue was negotiating with the utility for two new 38 kV class feeders, and the second was to fit 38 kV class switchgear in one half of the space normally required (all the room left in the approved electrical vault). Our firm worked hand-in-hand with a custom switchgear manufacturer to design a one-of-a-kind, high fault duty rated compact lineup that needed to be approved by both the city inspector and the utility. Working as a team to solve the problem, the city, the utility, and our firm produced a viable solution. This design is now being considered by the utility for Hurricane Sandy victims that must move their substations from below grade or at grade to higher floor locations. The more compact and lighter switchgear helps make such a migration more acceptable with fewer structural modifications needed.
Larson: When working with the University of Oregon, it needed its new systems to connect directly to the university’s grid rather than the local public utility district (PUD) grid. This required a very complex modeling program to ensure smooth operation and uninterrupted service. Eighty-nine potential switching configurations were established, either manually prompted by the university or by the automatic controls. The challenge was determining the appropriate data needed for proper simulation for each of those 89 configurations, as well as how to test without damaging the systems or equipment. This resulted in an extensive matrix that systematically kept track of the various possibilities. Based on the modeling results, the university was assured that the installation could work reliably.
CSE: How do you balance the need for reliable power with the desire for efficiency and sustainability?
Regan: As more of our projects seek to be LEED certified and the pressure is on to deliver efficient/sustainable projects, yet with high reliability, we must perform the needed balancing act. Interestingly, some thought processes for achieving efficiency goals lead to better reliability. Electrically, we see decisions to purchase more expensive high-efficient equipment such as transformers, HVAC equipment, and variable frequency drive (VFD) packages to save energy and decrease carbon footprint, and then there is the realization that this more costly equipment is actually more robust and reliable and, thus, achieves our reliability goals, too.
Larson: At the University of Oregon, we were able to use a cogeneration system that had the capability to increase power reliability without compromising the efficiency or sustainability of the system. The combined cycle system could be operated in parallel with the utility or as an independent grid or island, separate from the utility as a micro-grid. By operating in an island configuration, Wood Harbinger was able to mitigate any extended utility outage, thus maintaining campus operations. Because of the increased efficiency, the amount of fossil fuels released was dramatically reduced, and the university received a savings of more than $700,000.
CSE: What low- and medium-voltage power challenges have you overcome?
Larson: The project at the University of Oregon was a complex medium-voltage power solution. The new medium-voltage switchgear is a 4-bus ring configuration. Bus A was fed from the utility and connected to half of the campus feeders, Bus B also has a separate utility feed, 7.5 MW of cogeneration, and is connected to the other half of the campus; it is connected to Bus A via a tiebreaker. Bus G has three 2.275 MW diesel generators and room for a fourth, and it is connected to Bus A and Bus S via tiebreakers. Bus S feeds all the standby power feeders on campus, and is connected to Bus B and Bus G via a tiebreaker. The new chiller plant and upgrades to the boiler plant required a new service from the utility; this required the building to be on a new 60 MW double-ended substation for the university. Wood Harbinger worked with the university, the local utility, the contractor, the switchgear manufacturer, the diesel generator manufacturer, and the cogeneration equipment manufacturer to ensure that all the components would be able to be paralleled together and would correctly reconfigure the system and switchgear, without interrupting power to the campus, if any of the 89 scenarios happened.
Regan: On overseas projects, especially in developing countries, we often run into the problem of unskilled workers in a high-tech world. Some of these countries limit ex-patriot supervision and entrance into the country. On a project in the Middle East, the concept of duct banks, high-voltage splicing, and cable pulling was too much for the assigned (by the government) local contractor to grasp and execute. As they were very capable of digging trenches, we worked with a U.S. cable manufacturer to deliver “oversized reels” of 15 kV metal-clad armored cable, “cable in flexible conduit,” to our local contractor. We were able to run from switchgear to all terminals with no manholes, no cable pulling, and no splicing. All terminations, as there was a manageable amount, were handled by our ex-pat team of supervisors/splicers.
CSE: Describe a recent manufacturing/industrial facility project in which you specified standby or emergency power. What challenges did you face, and how did you overcome them?
Regan: We were designing the installation of a 1000 kW diesel generator at a refinery that was very heavily affected by Hurricane Sandy. Corporate mandate requires all affected equipment be raised 12 to 15 ft above existing grade. We had been designing a large 24 x 56-ft prefabricated substation on piles. Now a large rotating piece of machinery had to be added, yet have continuous walkways for access and egress. We had to isolate vibrations, waterproof all incoming/outgoing cables, and provide a built-in load bank while maintaining all the 4160 V and 480 V loads active in a hazardous area. We set up temporary distribution boards at 480 V and 4160 V to bypass the existing substation. While this work was being done, an alternate feed from an adjacent processing unit, backed up by standby generator, was brought to the temporary boards. Weekly scheduling and planning meetings quickly turned to daily and sometimes twice daily to execute the transfer without dropping the critical loads. With a great deal of engineer/owner/contractor cooperation, it was executed without disruption to the refinery.
Larson: The three 2.275 MW diesel generators installed at the University of Oregon provide a challenge in that two of the generators had to be on-line and paralleled together in less than 10 sec in order to meet the university’s requirements for its standby power. This required a lot of collaboration during construction between Wood Harbinger, the contractor, and the diesel generator manufacturer work through the paralleling requirements and to validate after installation that the requirements were met. Through the collaboration we were able to get two of the generators on-line and paralleled in less than 10 sec and the third paralleled in less than 15 sec.
CSE: Describe a project in which the client requested demand-response or Smart Grid technologies.
Regan: A major Northeastern city was determined to install a Smart Grid/micro-grid city-wide emergency generation system in the aftermath of Hurricane Sandy when all essential buildings were blacked out. As one of the largest cities in the state with little available footprint for micro-generation plants, it became both an engineering and real estate challenge. In order to garner state funding, the design had to pass muster with the state department of energy, the utility, and the governor’s office. Our engineers quickly determined the key city facilities, hospitals, and police stations that had to stay up in hurricane/flooding crises. The city endorsed those determinations and agreed that a large shelter location that we proposed made sense, and that was added to the list. We worked with the Federal Emergency Management Agency (FEMA) to outline best areas for those generation facilities. The end product won all the competitions we entered, garnering the city two-thirds of the statewide funding as the design was practical, reliable, cost-effective, and marketable to co-sponsoring developers. The plants will provide the needed power to support critical systems and even large shelters to house hundreds of possibly misplaced people after a major climatic event such as Hurricane Sandy.
Larson: In order to realize significant financial savings, the University of Oregon would require the co-gen to directly connect to the university grid via the new switch house, rather than direct to the local PUD grid, the Eugene Water and Electric Board. To create this direct connection and ensure continuity and uninterrupted service to the campus, an extensive computer modeling analysis was required using a type of software called electrical transient analysis program (ETAP), which provides simulated performance predictions of the utility PUD equipment, the standby generation, the co-gen, and the campus distribution. This analysis modeled the transient and dynamic nature of each of the electrical components in the system to demonstrate how the co-gen and protection schemes would react to planned and unplanned changes and interruptions to the system. It demonstrates protection and switching schemes as real-time events and can be modeled in software applications such as supervisory control and data acquisition (SCADA), so that the operators can do similar modeling to predict the outcome of a change of state during real-time, day-to-day operations.