Impacts of Electric Vehicle Charging on Electric Power Distribution Systems

Electric Avenue, located on the Portland State University (PSU) campus along SW Montgomery Street, is a joint project between Portland General Electric, 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, the authors 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, the authors 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 current transformers (CTs) and voltage transformers (VTs), protection settings and decisions regarding conductor ampacity. For this study, the authors 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. The authors also noted phase imbalance, phantom loading and other PQ issues observed during the course of the study. The objective is to expand the electric utility industry’s understanding that EVs have on these issues.


  • English

Media Info

  • Media Type: Digital/other
  • Edition: Final Report
  • Features: Appendices; Figures; Photos; References; Tables;
  • Pagination: 53p

Subject/Index Terms

Filing Info

  • Accession Number: 01641418
  • Record Type: Publication
  • Report/Paper Numbers: OTREC-SS-731
  • Created Date: Jul 24 2017 9:53AM