FIGURE 1 System impact analysis framework.
high localized concentrations are possible. Using known distribution system circuit information, PEV charge characteristics, and likely customer behaviors to construct models of system conditions, the analysis framework considers the following principal factors that define PEV loading on distribution systems: PEV market penetration levels per utility customer class (residential, commercial); different PEV charge spectrums (battery type, charger efficiency) and profiles; time profiles and likely customer charging habits; and battery state of charge based on miles driven.
To evaluate circuits from 19 utility operating territories, PEV adoption levels in the range of 2–25% were used. It’s important to note that, even for low overall customer PEV adoption rates, based on system configuration and assumed customer adoption probabilities PEV clusters will occur randomly throughout the system, as shown in Figure 2. Each PEV is represented by a circle, and as PEVs are introduced at the same location they are spaced like petals on a flower. Detailed analysis from 36 circuits in 19 utility operating territories revealed a penetration pattern that resembles sparse clusters that are nonuniform, centered on early adopter neighborhoods. Several of these distribution system segments have older homes and are capacity constrained. Higher penetration rates, of course, increase the potential for larger and more numerous clusters. Although these clusters may indicate an increased risk of higher than average loading levels, clustering alone does not signify the likelihood of negative impact because other PEV load characteristics must be taken into account.