The Role of Distributed Generation in Power Quality and Reliability

The hospital might also seriously consider CHP, were it not for financial and siting constraints.
The metal manufacturing plant also attempts to purchase equipment that can withstand less than
ideal power quality, varied operation to try to “catch” harmonics, sized motors and adjusted
overheads to protect against voltage/current sags, added isolators and power conditioners in
problem areas to avoid transient related problems and shifted some production to the night shift
to avoid power quality problems that are more likely to occur during summer days and evenings.
The “superalloy” manufacturer has installed a transformer substation to isolate internal plant
power quality from the surrounding distribution system, a standby generator with an automatic
transfer switch, other gas-fired emergency generators dedicated to emergency lighting circuits
and a 9,200 kVAR filter bank to deal with harmonic problems and power factor correction. A
temperature controlled (very cold) warehouse company sharing a building with a manufacturer
of plastic items installed a CHP system as well as a series of capacitors. A manufacturer of
precision plastic parts implemented one of the most comprehensive measures, installing a hybrid
onsite power system with both wind turbines and microturbines.
3.4 Site Analysis of DG/CHP Solutions
Of the nine firms interviewed:
• Two firms have active on-site CHP facilities. One, an upstate plastics manufacturer, cited
ongoing power quality and reliability problems as a major factor impelling it to consider
and ultimately install CHP.
• For the facility incorporating CHP as part of an overall strategy to improve power quality
and reliability, the situation has improved. The upstate plastics manufacturer has
indicated that phase imbalance problems that had repeatedly damaged microprocessordriven
equipment and ruined product have been resolved by virtue of its deployment of a
microturbine/wind hybrid system.
• An upstate copper and alloy manufacturer, faces a number of power quality issues,
ranging from voltage sags causing machines to trip; long duration over- and undervoltage
impacting the copper melting process; and harmonic noise. However, DG/CHP is
not considered to be an attractive option because: the company receives inexpensive
NYPA “Power for Jobs and Economic Development” making it more difficult to
undercut the cost with a CHP unit; the local utility’s standby tariff eliminates most of the
benefits of a system optimally sized to steam load; and the CHP system oversizing
necessary to avoid the utility standby charges requires excessive capital costs and would
result in less than optimal utilization factor.
• A hospital in Queens faces power quality issues ranging from relatively minor (blown
ballasts and computers when emergency generators run) to the life threatening (such as
when the back-up generator supplying life safety equipment was lost during the 2003
blackout). Financial resource constraints appear to be the major factor precluding the
hospital from pursuing CHP at this time. Difficulty finding a sufficiently large and
properly located site is another problem.
• Two other traditional manufacturing firms have indicated that external power quality
problems and reliability have not had a material impact on plant operations. One, a forge
Energy and Environmental Analysis / Pace Energy 14 The Role of DG in Power Reliability