Reliability worth assessment in electric power delivery systems

A very popular method utilized in quantifying the benefit of power delivery service reliability is to estimate the customer monetary losses associated with power supply interruptions by collecting data with customer surveys. MidAmerican Energy Company, a Midwest utility, recently performed surveys of its customers in the residential, commercial, industrial and company/organization sectors. This paper presents the overall results of these surveys with primary focus on the cost results. The results of this study are compared with the results of other studies performed in high cost areas of the United States east and west coasts. This is the first ever study of this nature performed for the electrical customers in the United States Midwest region. Methodological differences in study design compared to coastal surveys are discussed. The major contribution of this paper is that particulars of Midwest customers compared to customers of coastal utilities are noted, the impact on customers with backup supply is identified, a suggested approach to enhancing customer satisfaction due to advance warning on outages is recommended, and relatively high survey response return rates are elaborated. The customer damage functions derived from the survey results are being routinely used in power delivery project justifications in annual delivery system budgeting process.