APPA 2005 E&O Technical Conference Memphis, TN April 19, 2005 Reliability 101 APPA 2005 E&O Technical Conference Memphis, TN April 19, 2005 Gregg Turbeville, PE Supv, Distribution Planning Santee Cooper Myrtle Beach, SC

General term that means different things to different utilities. Reliability General term that means different things to different utilities. 4/19/2005 APPA 2005 E&O Technical Conference

APPA 2005 E&O Technical Conference What is Reliability? Definition 1. the trait of being dependable or reliable (trustworthy, stable, unfailing) WordNet ® 2.0, © 2003 Princeton University 4/19/2005 APPA 2005 E&O Technical Conference

APPA 2005 E&O Technical Conference What is Reliability? A subset of Power Quality Power Quality (sags, swells, transients, flicker, harmonic distortion) Reliability: subset of power quality that deals with customer interruptions. Availability - duration of interruptions Frequency of both sustained and momentary Reliability Indices: calculated values based on observed outage data for a set of loads, customers, feeders, territories, etc. 4/19/2005 APPA 2005 E&O Technical Conference

APPA 2005 E&O Technical Conference IEEE 1366-2003 IEEE 1366 is the IEEE Guide for Electric Power Distribution Reliability Indices. present terms and definitions foster uniformity in development of indices identify factors which affect the indices aid in consistent reporting practices provide tools for internal and external comparisons. 4/19/2005 APPA 2005 E&O Technical Conference

APPA 2005 E&O Technical Conference IEEE 1366-2003 Started in 1992 as the IEEE Working Group on Distribution Reliability IEEE 1366 issued in April 1999 as “Trial Use Guide for Electric Power Distribution Reliability Indices” [IEEE 1366-1998] Updated in 2001 as “Full Use Guide” Major revision issued in April 2004 4/19/2005 APPA 2005 E&O Technical Conference

What indices are you using to track and benchmark? Reliability Indices What indices are you using to track and benchmark? 4/19/2005 APPA 2005 E&O Technical Conference

APPA 2005 E&O Technical Conference Which indices are used? SAIDI > 80% SAIFI  80% CAIDI  70% ASAI  60% MAIFI  20% Others  20% (CAIFI, CTAIDI, CEMI, CEMSMI) 4/19/2005 APPA 2005 E&O Technical Conference

APPA 2005 E&O Technical Conference SAIDI System Average Interruption Duration Index Total duration of interruption for the average customer =  Customer Interruption Durations Total number of customers served 4/19/2005 APPA 2005 E&O Technical Conference

APPA 2005 E&O Technical Conference SAIDI example 100 customers on the system 14 customers experienced a 3-hour outage 14 x 3 = 42 hours or 2520 minutes SAIDI = 2520 = 25.2 100 Average of 25.2 minutes per customer 4/19/2005 APPA 2005 E&O Technical Conference

APPA 2005 E&O Technical Conference SAIFI System Average Interruption Frequency Index How often the average customer experiences a sustained interruption =  Total Number of Customers Interrupted Total number of customers served 4/19/2005 APPA 2005 E&O Technical Conference

APPA 2005 E&O Technical Conference SAIFI example 100 customers on the system 60 customers had a sustained interruption (or 30 customers had two interruptions: 30 x 2 = 60) SAIFI = 60 = 0.6 100 4/19/2005 APPA 2005 E&O Technical Conference

APPA 2005 E&O Technical Conference CAIDI Customer Average Interruption Duration Index The average duration of interruptions per customer that had an interruption The average time to restore service. =  Customer Interruption Durations Total number of customers interrupted 4/19/2005 APPA 2005 E&O Technical Conference

APPA 2005 E&O Technical Conference CAIDI example 100 customers on the system 10 customers experienced a 40-minute outage  Cust. Int. Duration = 400 minutes Total number of customers interrupted = 10 CAIDI = 400 = 40 10 Average of 40 minutes per interrupted customer. 4/19/2005 APPA 2005 E&O Technical Conference

APPA 2005 E&O Technical Conference ASAI Average Service Availability Index The fraction of time (percentage) that a customer has received power during the reporting period. = Customer Hours Service Availability Customer Hours Service Demands 4/19/2005 APPA 2005 E&O Technical Conference

APPA 2005 E&O Technical Conference ASAI example 365 days x 24 hours/day = 8760 hours per year 100 customers 876,000 customer-hours 44 customers experience a 60-minute outage (2640 customer-minutes, or 44 customer-hours) ASAI = 876,000 – 44 = 875,956 = 876,000 876,000 = .99995 or 99.995% 4/19/2005 APPA 2005 E&O Technical Conference

APPA 2005 E&O Technical Conference MAIFI Momentary Average Interruption Frequency Index The average frequency of momentary interruptions. MAIFI =  Total No. of cust. momentary interruptions Total number of customers served 4/19/2005 APPA 2005 E&O Technical Conference

APPA 2005 E&O Technical Conference MAIFI example 100 customers on the system (2 feeders, 50 customers each) 50 customers had 12 momentary interruptions; the other 50 customers had 8 momentary interruptions. (1 breaker had 12 operations; 1 breaker had 8) (50 x 12) + (50 x 8) = 600 + 400 = 1000 MAIFI = 1000 = 10.0 100 4/19/2005 APPA 2005 E&O Technical Conference

APPA 2005 E&O Technical Conference MAIFI continued MAIFI Two breaker operations followed by a successful reclose: MAIFI=2 MAIFIE - event MAIFI Two breaker operations followed by a successful reclose: MAIFIE =1 4/19/2005 APPA 2005 E&O Technical Conference

APPA 2005 E&O Technical Conference Interesting (?) facts Relationship between ASAI and SAIDI. If you know one, you can calculate the other. ASAI = Minutes per year – SAIDI min. Minutes per year 4/19/2005 APPA 2005 E&O Technical Conference

APPA 2005 E&O Technical Conference Interesting (?) facts If resources are unlimited, can you set a goal and successfully improve all your indices? No… SAIDI =  Customer Interruption Durations Total number of customers served SAIFI=  Total Number of Customers Interrupted Total number of customers served 4/19/2005 APPA 2005 E&O Technical Conference

APPA 2005 E&O Technical Conference SAIDI =  Customer Interruption Durations SAIFI Total number of customers served  Total Number of Customers Interrupted Total number of customers served  Customer Interruption Duration = CAIDI Total number of customers interrupted CAIDI = SAIDI SAIFI SAIFI goes down, CAIDI goes UP. 4/19/2005 APPA 2005 E&O Technical Conference

APPA 2005 E&O Technical Conference Comparisons Can you compare your utility’s reliability to those located a few states away? 4/19/2005 APPA 2005 E&O Technical Conference

APPA 2005 E&O Technical Conference Definitions Standard definitions may not be the same as your utility’s definition or your neighbor’s definition. Standard definitions may change or evolve over time. 4/19/2005 APPA 2005 E&O Technical Conference

APPA 2005 E&O Technical Conference Loss of service 1998 definition The loss of electrical power, a complete loss of voltage to one or more customers. 2003 definition A complete loss of voltage on at least one normally energized conductor to one or more customers. 4/19/2005 APPA 2005 E&O Technical Conference

APPA 2005 E&O Technical Conference Distribution system The distribution system is generally considered to be anything from the distribution substation fence to the customer meter. Often the initial overcurrent protection and voltage regulators are within the substation fence… 1998 - “period.” 2003 - and are considered to be part of the distribution system. 4/19/2005 APPA 2005 E&O Technical Conference

APPA 2005 E&O Technical Conference Number of customers Is this the A) average number of customers during the reporting period, or B) the number of customers at the end of the reporting period? 1998 - total number at end 2003 - average number 4/19/2005 APPA 2005 E&O Technical Conference

Momentary vs Sustained Utilities commonly use one minute, three minutes, or five minutes. IEEE has referenced five minutes since early days of the working group. We always used one minute, but recently changed with 2003 standard. 4/19/2005 APPA 2005 E&O Technical Conference

APPA 2005 E&O Technical Conference Variations Level of automated data (connected OMS model vs. estimated customer count) System design, geography, weather, maintenance, vegetation management... 4/19/2005 APPA 2005 E&O Technical Conference

APPA 2005 E&O Technical Conference Exclusions Interruptions that occur as a result of outages on customer-owned facilities or loss of supply from another utility. Substation/transmission - upstream of defined distribution system. Data classification exclusions (major events? planned interruptions?) 4/19/2005 APPA 2005 E&O Technical Conference

APPA 2005 E&O Technical Conference Major Event Day Major Storm has now been redefined as major event day (MED) Large variation between companies on how to define a major storm. IEEE definitions changed over time and were often not specific. The new method is a statistical approach using previous five years of data. This has been considered by IEEE since 1992, but not incorporated into standard until 2003 version. 4/19/2005 APPA 2005 E&O Technical Conference

APPA 2005 E&O Technical Conference Major Event Day Allows major events to be studied separately. Better reveals trends in daily operation that would be hidden by impact of major events. Old methods had difficulties in creating a uniform list of types of major events. extensive mechanical damage; widespread damage catastrophic event named stormed; NWS reference 10% of customers interrupted Understandable, easy to apply, specific, fair Exclusions are based on each utility’s recent past performance. 4/19/2005 APPA 2005 E&O Technical Conference

APPA 2005 E&O Technical Conference 2.5 Beta Method Based on the statistical principal of standard deviation (). Beta is used because Natural log of data is used Outage data only has positive values. 4/19/2005 APPA 2005 E&O Technical Conference

APPA 2005 E&O Technical Conference MED – 2.5 Beta Daily SAIDI data for 5 years Cluster plot 4/19/2005 APPA 2005 E&O Technical Conference

APPA 2005 E&O Technical Conference MED – 2.5 Beta Raw data and LN(data) - sorted 4/19/2005 APPA 2005 E&O Technical Conference

APPA 2005 E&O Technical Conference MED – 2.5 Beta LN(SAIDI) w/ “imaginary” component 4/19/2005 APPA 2005 E&O Technical Conference

Specific MED exclusions 4/19/2005 APPA 2005 E&O Technical Conference

Santee Cooper Reliability We have been tracking reliability data since 1989 Early years used: Draft #2 of the IEEE working group (July 1992) IEEE 859-1987 – standard terms for reporting transmission outages “Utilities need a standard measure of performance” Electric World, Oct 1991 Internal opinion Added to corporate goals (incentive) in 1996 Migrated to IEEE standard over time 4/19/2005 APPA 2005 E&O Technical Conference

APPA 2005 E&O Technical Conference Santee Cooper data Date Time Area Circuit ID Equipment type Equipment # # of customers Minutes Customer-minutes Cause Outage (forced/planned) Isolating Equipment Damaged Equipment Type (OH/UG) Case# Assigned To Assigned Time Repaired by Repaired Time Total customers Length of outage Customer outage time Transformer info Comments Repair Action Reliability Y/N 4/19/2005 APPA 2005 E&O Technical Conference

APPA 2005 E&O Technical Conference 4/19/2005 APPA 2005 E&O Technical Conference

APPA 2005 E&O Technical Conference Santee Cooper data 4/19/2005 APPA 2005 E&O Technical Conference

APPA 2005 E&O Technical Conference OMS Improvement More accurate customer counts Outage times tracked more accurately grouping customers into outages restoration times for those outages Accurate, real-time statistics Better data for reporting and decision making Reliability statistics may go down, although “real” reliability should improve due to device prediction and efficient dispatch 4/19/2005 APPA 2005 E&O Technical Conference

Monthly Reliability Report 4/19/2005 APPA 2005 E&O Technical Conference

APPA 2005 E&O Technical Conference ASAI Graph 4/19/2005 APPA 2005 E&O Technical Conference

APPA 2005 E&O Technical Conference Animal Related Stats 4/19/2005 APPA 2005 E&O Technical Conference

APPA 2005 E&O Technical Conference Specific Analysis 4/19/2005 APPA 2005 E&O Technical Conference

Customer-Minutes per Failed Equipment 4/19/2005 APPA 2005 E&O Technical Conference

APPA 2005 E&O Technical Conference Santee Cooper uses Target for Distribution Services within the Corporate Goals program. (ASAI=99.995%) Line crew service centers have a target goal of outage time not to exceed 68 minutes. MAIFI data is used for circuit patrol (>5). Composite index = (SAIDI) + (SAIFI) + (MAIFI) is used to rank circuits for overhead and underground maintenance. where  = [weight, index, index target] Damage claim research. Future uses will center around Reliability Planning where more detailed analysis of circuits will recommend more specific actions for underperforming circuits. 4/19/2005 APPA 2005 E&O Technical Conference

APPA 2005 E&O Technical Conference Adopt a standard IEEE 1366 Other state or PUC standard may apply. Helps maintain consistency and is based on best practices Gives you “solid ground” to stand on when results and performance are questioned Best chance in allowing you to compare yourself to other utilities. 4/19/2005 APPA 2005 E&O Technical Conference

APPA 2005 E&O Technical Conference References IEEE Std 1366-2003 IEEE Guide for Electric Power Distribution Reliability Indices http://standards.ieee.org $63 ($52) softcover, $55 ($45) PDF Electric Power Distribution Reliability, Richard Brown, ABB, Marcel Dekker Inc, 2002 4/19/2005 APPA 2005 E&O Technical Conference

APPA 2005 E&O Technical Conference Reliability 101 Questions? 4/19/2005 APPA 2005 E&O Technical Conference