ELECTRIC POWER DISTRIBUTION SYSTEM RELIABILITY AND OUTAGE COSTS: An Undergraduate Industry Collaboration

This paper describes an undergraduate, cross-disciplinary research into the economic effects that result from power system outages, which are useful for utility planning and assessing the valuation of electric grid reliability. The Pacific Northwest region of the United States experiences a temperate climate with brief summers and long-lasting winters. Generally, the highest electric demand for the region occurs during winter months, due to the need for heating. Therefore, an outage that occurs during cold weather could result in additional non-financial costs for customers (i.e., loss of comfort services such as electric heating, etc.). Outages that occur due to natural disasters such as hurricanes are not present in this region, unlike the East Coast of the United States. However, the region's abundant vegetation (i.e., trees) do impact the distribution system, especially during storm seasons, such as fall and winter, as they can cause faults on the distribution lines. This report examines the causes and consequences of electricity outages using a variety of metrics such as the Consumer Damage Function (CDF), Value of Lost Load (VOLL), Loss of Load Probability (LOLP), and other commonly used metrics for research and utility resource planning. The methods for estimating and analyzing the economic impacts of power outages include post-event analysis, economic output to energy consumption ratios, and electric customer surveys. Regression analysis (i.e., using Tobit specification) is performed on the data collected from a survey of the Pacific Northwest electric customers to estimate the Customer Damage Function (CDF), based on factors such as the duration and timing of an outage. The Department of Energy's (DOE) Interruption Cost Estimator (ICE) Calculator is used to assess the impacts of outages based on reliability data provided from the region's largest investor-owned utility, Puget Sound Energy (PSE). The reliability metrics include System Average Interruption Duration Index (SAIDI), which describes the average length of an outage in minutes, the System Average Interruption Frequency Index (SAIFI), which describes the average number of outages a customer experiences, and the Customer Average Interruption Duration Index (CAIDI), which is the average outage duration any given customer would experience and is the result of SAIDI divided by SAIFI. These three metrics from Puget Sound Energy were used in the regression analysis along with the number of customers the utility serve, separated out between non-residential and residential customers. This project was conducted in collaboration between two undergraduate students, an electrical engineering faculty specializing in power systems, and engineers from a local utility. The natural of the research was interdisciplinary as it required both economics and power engineering knowledge, which was a challenge but also very rewarding for the students. The students reached out to the local utility and worked with the engineering team there to conduct this research that is in turn both beneficial for the students and the utility. This partnership not only stimulated the students' interest in research but also helped them develop skills in communication, project management, and soft skills that will serve them well into their professional careers. The opportunities and challenges from this collaboration are also presented in this paper.