Palmer House Hilton – Private Dining Room 9 A Comparable Method for Benchmarking the Reliability Performance of Electric Utilities Dan Kowalewski 630-437-2905 daniel.kowalewski@exeloncorp.com IEEE PES 2002 Summer Meeting Chicago, Illinois Palmer House Hilton – Private Dining Room 9 Monday, July 22, 2002 – 2:00 to 5:00 PM

Overview Criteria and Desired Elements Analysis Conclusions Approach Alternatives Considered Proposed Application Rules Calculation Specifics Analysis Results Conclusions

Event Criteria Create Event Exclusion Criteria Facilitates Consistent Exclusions Allows “Fair” Benchmarking Provides Information to Understand Performance Trends Repeatability of Results

Desired Elements Has Clear Rules for Application and Exclusion Removes Subjectivity Scales to Various Sized Utilities Removes Outlying Events Removes Major Weather Variability Allows Trends to Appear Balances Operational Concerns Frequency Duration Allows for Consistent Results Ease of Calculation

Analysis: Approach Compare Proposed Methods to Understand Consistency and Understandability Differences of Exclusions Impacts on Different Sized Companies Variability of Results A Great Deal of Confusion Initially Methodology and Calculation Approach was Not Clear 3 Years vs 5 Years of Historic Data Log vs Non-Log Data Basis Unclear: SAIDI, SAIFI, Customer Minutes Had to Apply Data to Understand Traded Methodology and Results Ensures Consistent Application Expanded Understanding with Broader Data Set

Analysis: Alternatives Considered Traditional 10% IEEE Definition ComEd Region ComEd PECO Bootstrap 3 Year Historic 5 Year Historic 2.5 or 3 Beta (SAIDI per Day) 6 Beta (SAIDI per Day) Other Analysis SAIDI per Calendar Day Start Time of Interruption Customer Interruption Minutes Experienced per Day Rolling 24 Hour Window

Alternative Comparison Removes Weather Variability Clear Rules for Exclusion Removes Subjectivity Removes Outliers Balances Frequency Balances Duration Ease of Calculation Allows Trending Scalability

ComEd Major Event Days * * * * * * * Based On Outage Start Date * * Customer Interruption Minutes by Calendar Day * * * Based on 24 hour rolling customer outages

* Based On Outage Start Date ComEd Major Event Days * * Based On Outage Start Date

3 Beta SAIDI Day -Threshold Calculation IEEE data (all outages > 5minutes) Five years of most recent historic SAIDI per day data Take the log of SAIDI per day values Calculate the mean Calculate the population standard deviation Calculate the mean plus 3 times the standard deviation Convert back to SAIDI per day values by taking the exponential of the calculated mean plus 3 times the standard deviation number Results in a Threshold Exclusion value Threshold value is applied to the year following the five-year data analysis period All days with SAIDI greater than or equal to the calculated Threshold value are considered Major Event Days

Thresholds of Daily SAIDI (3 Year Rolling)

Thresholds of Daily SAIDI (5 Year Rolling)

Variability of Thresholds

PECO - Variability of Thresholds Bootstrap 3 Beta 3 Beta Bootstrap Bootstrap Thresholds can be highly volatile, especially with few years of data (the saturation effect).

ComEd Daily SAIDI (1998 - 2001)

ComEd Daily SAIDI (1998 - 2001)

ComEd Daily SAIDI (1998 - 2001)

Conclusions Recommend 3 Beta SAIDI per Day Achieves Objectives Consistent Facilitates Fair Benchmarking Provides Information to Understand Performance Trends Repeatability of Results Proven with REAL Data