For many years, electricity distribution companies have used sustained interruption indices as indicators of the reliability of service provided on their systems. Today, however, many electricity consumers are adversely affected by more subtle voltage disturbances such as sags and swells. Many utilities are well aware of such service quality concerns and are implementing extensive monitoring systems to detect such disturbances and assess service quality in this regard. This paper presents a subset of work completed which provides utilities with tools to make more complete service quality assessments. Indices developed to reflect system service quality with respect to all rms variations are presented. Example values for the indices are calculated using data from a national distribution power quality data collection project. Finally, an example application of the indices currently being made by a distribution utility is discussed.

Analyses have shown that electric vehicle (EV) loads may considerably affect the secondary service voltage quality. One of the ways to mitigate voltage drop concerns is to use a time-of-use (TOU) pricing scheme. A TOU pricing scheme utilizes the off-peak generation for EV charging, thus deferring any immediate grid upgrade and improving the grid sustainability. This paper evaluates various aspects of EV charging under a TOU schedule, with off-peak rates starting at hours ranging from 8 P.M. to 3 A.M. The study is conducted using an actual residential distribution circuit. A best practical time to begin the off-peak rates is determined so that the effects of EV charging on the secondary service voltages are minimized while ensuring that EVs are fully charged by 7 A.M., thus maximizing both grid and customer benefits. The analysis suggests that the best time to begin off-peak rates is between 11 P.M. and 12 A.M. Furthermore, the analysis also suggests that setting up TOU off-peak rates at the latter half of the peak load demand, for example, at 8 P.M., is detrimental to the distribution circuit voltage quality. The result indicates that the existing utility TOU scheme may exacerbate voltage drop problems due to EV load charging. INDEX TERMS Distribution system, electricity market, electric vehicle (EV), time-of-use (TOU) pricing.

The system impact of a new transit substation may include harmonic distortion, voltage unbalance, and flicker. Measurements were taken at a similar substation, and system simulations were performed for the planned substation. It was found that the Metro North train load produced significant levels of third harmonic current. Resonances in the 115-kV system were simulated and found to be at frequencies which are not critical. A third harmonic filter is needed in order to meet IEEE 519 requirements. Unbalance and flicker were found to be negligible.Index Terms-Harmonic analysis, power quality, rail transportation power systems.

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