Electric Avenue, located on the PSU campus along SW Montgomery Street, is a joint project between Portland General Electric, Portland State University (PSU) and the City of Portland. Launched in August 2011, Electric Avenue is intended as a research platform for understanding the impact electric vehicles have within the larger context of the city. For this research, we used Electric Avenue to investigate the impacts electric vehicles (EVs) may have on electric power distribution systems. Nonlinear loads, such as EV chargers, will often introduce power quality (PQ) issues within distribution circuits, which can have detrimental effects on system components. PQ encompasses several specific concepts such as harmonic distortion, DC offset, phase imbalance, and voltage deviations, among others, and these are quantified in myriad ways. For this study, we focus on harmonic currents since these have the potential to affect the lifetime of magnetic assets such as distribution transformers and instrument transformers. Utilities plan asset management by anticipating the nature of loads and selecting assets designed to handle those loads. A deeper understanding of these matters specific to EVs will aid utilities in the design of distribution systems and provide guidance for asset planning. A load's PQ affects magnetic assets because of the potential for insulation failure and core saturation. Understanding the PQ of nonlinear loads assists distribution engineers with the selection of k-factor ratings for distribution transformers, selection of CTs and VTs, protection settings and decisions regarding conductor ampacity. For this study, we measured the PQ of EV chargers, paying specific attention to total harmonic distortion (THD) of individual EV chargers and total demand distortion (TDD) of the Electric Avenue service. We also noted phase imbalance, phantom loading and other PQ issues observed during the course of our study. Our objective is to expand the electric utility industry's understanding that EVs have on these issues. 17.

In distribution system planning, it is essential to understand the impacts that EVs and the power electronics associated with their charging units may have on power distribution networks. A deeper understanding of these matters aids utilities in the design of electrical power systems, including asset planning, an example being selection of k-type rating for distribution transformers. In this paper we present a method utilizing a VHDL-AMS environment for modeling these nonlinear, time-varying loads.

Nicole Zimmerman is an MS candidate in the Electrical & Computer Engineering department at Portland State University. She has worked as a research and teaching assistant in the Power Engineering Education Lab since her final year as an undergraduate at PSU. Nicole has contributed to several projects during that time, including analyses of natural ester oils as replacements for mineral oil in transformers and an HVDC feasibility study. Her thesis work employs VHDL-AMS in order to create generalized models of electric vehicle charging circuits for use in a tool designed to aid distribution engineers in planning electric vehicle charging installations.

In power distribution system planning, it is essential to understand the impacts that electric vehicles (EVs), and the non-linear, time-variant loading profiles associated with their charging units, may have on power distribution networks. This research presents a design methodology for the creation of both analytical and behavioral models for EV charging units within a VHDL-AMS simulation environment.Voltage and current data collected from Electric Avenue, located on the Portland State University campus, were used to create harmonic profiles of the EV charging units at the site. From these profiles, generalized models for both single-phase (Level 2) and three-phase (Level 3) EV chargers were created. Further, these models were validated within a larger system context utilizing the IEEE 13-bus distribution test feeder system. Results from the model's validation are presented for various charger and power system configurations. Finally, an online tool that was created for use by distribution system designers is presented. This tool can aid designers in assessing the impacts that EV chargers have on electrical assets, and assist with the appropriate selection of transformers, conductor ampacities, and protection equipment & settings.