Steven M. Brown, Associate Editor
Although power system reliability concerns dominated headlines this summer, power quality is an issue also achieving top-of-mind status among utilities and the commercial and industrial customers they serve. Microprocessor-based equipment used in the new digital economy requires not only a steady flow of power, but a steady flow of clean, balanced power free of sags, swells and flicker. Even old economy mainstays, like manufacturing, are feeling the bite of power quality disturbances as variable frequency drives and other modern equipment become more sensitive to power fluctuations.
Power that deviates from the pure waveform can be devastating to modern business. According to the Electric Power Research Institute (EPRI), power quality events in the United States in 1999 resulted in the loss of $50 billion in productivity and replacement of damaged equipment and inventory. A subsequent report from Banc of America Securities predicted that “with an increasing percentage of U.S. commerce expected to be conducted over the Web over the next five years, EPRI’s $50 billion loss estimate could rapidly escalate to more than $100 billion.”
With tens of billions of dollars at stake, it’s not surprising that power quality awareness is up. Jason Sheppard, marketing manager for utility systems at Power Measurement, says awareness of power quality is increasing on both the customer and the utility side of the meter. Power Measurement specializes in enterprise energy management systems, including power quality measurement through advanced metering technology. Sheppard said that many utilities are trying to differentiate themselves based on the level of power quality they can offer. And some unregulated utility entities are basing business around the provision of advanced power quality services.
According to Sheppard, a good deal of power quality problems can be traced to the same root cause of many reliability issues-a power delivery infrastructure that was not originally designed to support today’s businesses. But when it comes to power quality disturbances, the problems aren’t always on the outside of the customer’s facility.
“A lot of utilities are running into issues where either their own system or the customer’s electrical system was designed to power lighting and large motors, and in a lot of instances it’s not up to snuff for the type of equipment used in the digital economy,” Sheppard said.
The equipment running within a customer’s facility can cause power quality disturbances as well, but regardless of whether the source of the disturbance is on the customer side or the utility side of the meter, the customer often expects the utility to identify and remedy the problem. That would be the case particularly in a deregulated, competitive market.
“In a deregulated marketplace, the customer has the freedom to choose a utility or other service provider that can help them mitigate their power quality problems,” Sheppard said.
Sheppard said that some large commercial and industrial utility customers are attracted to the idea of siting their facilities closer to utility substations as a means of lessening the risk of power quality and reliability-related disturbances.
Some commercial and industrial operations may take the concept of siting facilities close to the source of power even further by looking to distributed generation (DG) as a supplement to the grid’s supply. Using DG to remedy supply shortfalls has become a popular topic, but at the present DG’s viability as a solution for power quality disturbances has come into question. A report published in December 2000 by EPRI (“Power Quality Impacts of Distributed Generation: Guidelines”) discussed the possibility of using DG to mitigate power quality problems. EPRI’s study showed that given “current technology, interconnection standards and utility distribution system practices, it is possible that the impact of DG on power quality will be neutral at best; and, as DG becomes a significant portion of the distribution feeder load, it could have a negative impact.” The EPRI report suggested that voltage harmonic distortion and temporary overvoltages as customers island themselves from the grid would be among the issues impeding DG’s use as a customer-side power quality enhancer.
Sheppard remains optimistic about DG’s potential. “DG may present some challenges; however, enterprise energy management systems offer the real-time control and verification capabilities needed to tightly coordinate generator operations, which should in turn avoid many of the negative impacts,” he said.