Efficiencies in Distribution Design and Operating Practices Mid-Study Analysis (February 2007)

This paper is a follow-up to the "efficiencies in distribution design and operating practices" paper presented at the rural electric power conference, 2005. It presents results of analysis of the data at the mid point (six months) of the study. By operating utility distribution systems in the lower range of the ANSI C84.1 allowable voltage limits, both the utility and the customer will benefit by having lower energy costs and high quality power. The basis of this conclusion is that electric load is not 100% constant power (PQ) load, but is actually a combination of constant power, constant impedance, and constant current. Performing cost-effective improvements to the distribution systems reduces the total voltage drop on the distribution feeder and changing the operation of the voltage regulation equipment reduces the average voltage level on the feeder. The results at mid-project show an overall energy savings by reducing the operating voltage with no adverse effect on the customer; the results are within expected values of 1 to 3 percent total energy reduction. Operating a utility distribution system in the lower half of the acceptable voltage range (120-114 volts) does save energy, reduces demand, and reduces VAR requirements. The Load Research project produced voltage reductions from 3.6% to 5.2% resulting in an average CVR_f of 0.55% with an overall relative precision of 10.7% at a 90% confidence level. The voltage reduction for the Pilot Demonstration Project (measuring substation bus voltage) ranged from 0.93% to 3.54% resulting in an average CVR_f of 0.86 with a relative precision of 13% at a 90% confidences level