IEEE 1366- Reliability Indices

1 IEEE Boston Section- February 19, 2019 John Teixeira, National GridIEEE 1366- Reliability IndicesSome Important Definitions3 National Grid foster uniformity in the development of distribution service Reliability Indices and to aid in consistent reporting practices among utilities. provide guidance for new personnel in the Reliability area and to provide tools for internal as well as external comparisons. Purpose of IEEE-13664 National Grid Customer: A metered electrical service point for which an active bill account is established at a specific location. Sounds like common remember:A Three-decker is three apartment building may be 100 doesn t doesn t s a customer5 National Grid Interruption: The total loss of electric power on one or more normally energized conductors to one or more customersconnected to the distribution portion of the system. Does not include Power Quality issues (sags, swells, etc.)

2 Part power?Loss of power not voltage ?Outage: The loss of ability of a componentto deliver power. Interruption vs. OutageDistinction:Interruption refers to CUSTOMERSO utage refers to EQUIPMENT6 National Grid Momentary Interruption: The briefloss of power delivery to one or more customers caused by the opening and closing operation of an interrupting device. Each recloser operation is a separate momentary interruptionSustained Interruption: Any interruption not classified as a part of a momentary event. That is, any interruption that lasts more than five minutes. Some companies and/or jurisdictions may use one minute or some other vs. Sustained InterruptionThe original intent was probably to exclude interruptions restored by automatic operation7 National Grid Interruption Duration: The time period from the initiation of an interruption until service has been restored to the affected customers. Step Restoration: The process of restoring all interrupted customers in stages over time.

3 Duration and Step Restoration8 National Grid CI = Customers InterruptedCMI = Customer Minutes InterruptedCS = Customers Served (IEEE 1366 call this NT)Fundamental FactorsCAIDI and Her Sisters10 National Grid SAIFI (System Average Interruption FrequencyIndex):How often the average customer experiences an interruptionSAIDI (System Average Interruption DurationIndex)The total number of minutes (or hours) of interruption the average customer experiencesCAIDI (CustomerAverage Interruption DurationIndex)The average time required to restore service Be careful with this one. The numbers can be Big Three- SAIFI, SAIDI, CAIDI11 National Grid Sustained interruptions only (no momentary)Usually applied over a specified time period (typically one year)Usually applied over a specified customer base (typically an entire system, state, town, feeder, etc.)Averages can be the average system SAIFI is That s pretty if 90% of customers had no interruptions and 10% had 5, is that good?

4 Comments on the Big ThreeThe Building Blocks-Calculating CI and CMI13 National Grid CI and CMI provide the basis for calculating the indicesTypical Distribution Feeder- Calculate CI and CMI14 National Grid CS = 10CS = 500CS = 15CS = 1000 Total Customers Served= 1525 Customers Served by Branch15 National Grid CS = 10CS = 500CS = 15CS = 1000 XFault OccursSimple Fault16 National Grid CS = 10CS = 500CS = 15CS = 1000 XOpenFault OccursFuse Opens10 Customers out for 90 minutesCI = 10 CMI = (10) * (90) = 900 CMIS imple Fault17 National Grid CS = 10CS = 500CS = 15CS = 1000 Fault OccursRecloser Operation18 National Grid CS = 10CS = 500CS = 15CS = 1000 Open2 reclose operationsFault OccursStation recloser trips and recloses twice at 10 sec. intervalsRecloser locks out (stays open)2 hours to restore (120 minutes)Recloser Operation19 National Grid CS = 10CS = 500CS = 15CS = 1000 Open2 reclose operationsCI = 1525 Momentary interruptions do not countDuration = 120 minutesCMI = (1525) * (120) = 180,000 CMIR ecloser Operation20 National Grid CS = 10CS = 500CS = 15CS = 10001.

5 Fault occurs on fused branchRecloser With Fuse Save21 National Grid CS = 10CS = 500CS = 15CS = occurs on fused recloser tripsRecloser With Fuse Save22 National Grid CS = 10CS = 500CS = 15CS = 100010 sec occurs on fused recloser recloser closes in 10 secondsRecloser With Fuse Save23 National Grid CS = 10CS = 500CS = 15CS = 1000 Successful occurs on fused recloser recloser closes in 10 opensRecloser With Fuse Save24 National Grid CS = 10CS = 500CS = 15CS = 1000 Successful occurs on fused recloser recloser closes in 10 minutes to restoreRecloser With Fuse Save25 National Grid CS = 10CS = 500CS = 15CS = 1000 Successful recloseOpensCI = 15 Momentary interruptions do not countDuration = 45 minutesCMI = (15) * (45) = 675 minutesRecloser With Fuse Save26 National Grid 27 National Grid CS = 10CS = 500CS = 15CS = 1000 Step Restoration28 National Grid CS = 10CS = 500CS = 15CS = occursStep Restoration29 National Grid CS = 10CS = 500CS = 15CS = recloser/breaker opens and locks outStep Restoration30 National Grid CS = 10CS = 500CS = 15CS = recloser/breaker opens and locks Minutes later:Open SwitchClose breakerStep Restoration31 National Grid CS = 10CS = 500CS = 15CS = recloser/breaker opens and locks Minutes later:Open SwitchClose breaker4.

6 60 minutes laterClose switchAll customers restoredStep Restoration32 National Grid CS = 10CS = 500CS = 15CS = 1000 Step Restoration33 National Grid CS = 10CS = 500CS = 15CS = 1000 OpenCI = 1525 (the entire circuit)Duration = 20 minutesCMI = (1525) * (20) = 30,500 minutesStep 134 National Grid CS = 10CS = 500CS = 15CS = 1000 CloseOpenCI = 515 Duration = 60 minutesCMI = (515) * (60) = 30,900 minutesStep 235 National Grid CI = 1525 Event TotalCS = 10CS = 500CS = 15CS = 100036 National Grid CS = 10CS = 500CS = 15CS = 1000CI = 1525 (each customer experienced only 1 interruption)CMI = (step 1) + (step 2)Event Total37 National Grid CS = 10CS = 500CS = 15CS = 1000CI = 1525 (each customer experienced only 1 interruption)CMI = (30,500) + (30,900)Event Total38 National Grid CS = 10CS = 500CS = 15CS = 1000CI = 1525 (each customer experienced only 1 interruption)CMI = (30,500) + (30,900) = 61,400 minutesEvent TotalCalculating SAIFI, SAIDI and CAIDI40 National Grid 4 events in our universe:Assume that this is the only feeder in our systemCalculate SAIFI, SAIDI, and CAIDIT otal of All EventsEventTypeCICMI1 Fuse Branch10 900 2 Feeder Outage1,525 180,000 3 Fuse Save15 675 4 Step Restoration1,525 61,400 Total3,075 242,975 41 National Grid CS = 1,525CI = 3,075 CMI = 242,975 Calculate.

7 SAIFI, SAIDI, CAIDI= CICS=30751525= CMI =2429751525=159= SAIDISAIFI= =2429753075=7942 National Grid Four FeedersLet s Expand Our UniverseFeederCSCICMI11,525 3,075 242,975 22,200 3,000 120,000 3800 875 50,000 42,000 200 15,000 43 National Grid Four FeedersMaybe this is an entire utility, maybe it s a town or districtLet s Expand Our UniverseFeederCSCICMI11,525 3,075 242,975 22,200 3,000 120,000 3800 875 50,000 42,000 200 15,000 Total6,525 7,150 427,975 44 National Grid CS = 6,525CI = 7,150 CMI = 427,975 Calculate: SAIFI, SAIDI, CAIDI= CMI =4279756525=66= CICS=71506525= =4279757150=60= SAIDISAIFI= Lesser Known Cousins46 National Grid CAIFI: Customer Average Interruption FrequencyIndexCTAIDI: Customer Total Average Interruption DurationIndexSimilar to SAIFI and SAIDI EXCEPT Only includes customers that actually experienced an interruptionCAIFI and CTAIDICAIFI=CITotal number of distinct customers interruptedCTAIDI=CMIT otal number of distinct customers interrupted47 National Grid Why?

8 Let s say that a company s overall Reliability is:SAIDI = 90 minutesSAIFI = half the company is served by a secondary network that hasn t and an interruption in the past ten that important?Averages can deceiveCAIFI and CTAIDI48 National Grid CEMIn: CustomersExperiencing Multiple InterruptionsCELID: CustomersExperiencing Long Interruption DurationsIntended to give a view of the relative number of customers with Reliability below some thresholdThese are both measured in PERCENTCEMI nand CELIDCEMIn=Tot num of customers that experienced n or more sustained interruptionsCSCELID=Tot num customers that experienced S or more hours durationCS49 National Grid MAIFI: Momentary Average Interruption Frequency IndexMAIFIE: Momentary Average Interruption Event Frequency IndexCEMSMIn: Customers Experiencing Multiple Sustained Interruption and MomentaryInterruption EventsMomentary: MAIFI, MAIFIE, CEMSMIn50 National Grid MAIFI: Momentary Average Interruption Frequency Index- Similar to SAIFIMAIFIE.

9 Momentary Average Interruption Event Frequency Index- Excludes momentaries associated with a sustained interruption (counts events)CEMSMIn: Customers Experiencing Multiple Sustained Interruption and MomentaryInterruption Events- Similar to CEMInMomentary: MAIFI, MAIFIE, CEMSMIn51 National Grid ASIFI: Average System Interruption FrequencyIndexASIDI: Average System Interruption DurationIndexSimilar to SAIFI and SAIDI but based on kVArather than customersLoad Based: ASIFI, ASIDIASIDI=Connected kVA duration of load interruptedTotal connected kVA served=kVA)(MinuteskVAASIFI=Total connected kVA of load interruptedTotal connected kVA served=kVAkVALies, Damn Lies, and Statistics53 National Grid Ckt. ACkt. B#2#1#3#5#6#4#7CS=100CS=100CS=100CS=100C S=100CS=100 Norm. OpenSimple two feeder systemCS = 600 Seven switchesEffect of Distribution Automation54 National Grid Assume:No automationManual switching time: 20 minutesRepair time: 60 minutesCkt.

10 ACkt. B#2#1#3#5#6#4#7CS=100CS=100CS=100CS=100C S=100CS=100 Norm. Open55 National Grid Ckt. ACkt. B#2#1#3#5#6#4#7CS=100CS=100CS=100CS=100C S=100CS=100 Norm. OpenTime ActionCust out0:00 Fault200#2 open auto56 National Grid Ckt. ACkt. B#2#1#3#5#6#4#7CS=100CS=100CS=100CS=100C S=100CS=100 CloseTime ActionCust out0:00 Fault200#2 open auto0:20#3 open manually100#4 close manually57 National Grid Ckt. ACkt. B#2#1#3#5#6#4#7CS=100CS=100CS=100CS=100C S=100CS=100 OpenTime ActionCust out0:00 Fault200#2 open auto0:20#3 open manually100#4 close manually1:20#3 close manually0#2 close manually#4 open manually58 National Grid 59 National Grid Assume:Distribution AutomationRepair time: 60 minutesCkt. ACkt. B#2#1#3#5#6#4#7CS=100CS=100CS=100CS=100C S=100CS=100 Norm. Open60 National Grid Ckt. ACkt. B#2#1#3#5#6#4#7CS=100CS=100CS=100CS=100C S=100CS=100 CloseTimeCust out0:00 Fault100#2 opens auto#3 opens auto#4 closes auto61 National Grid TimeCust out0:00 Fault100#2 opens auto#3 opens auto#4 closes auto1:00#2 close manually0#4 open manuallyCkt.