DISTRIBUTION SYSTEM ELECTRIC INFRASTRUCTURE RELIABILITY PERFORMANCE INDICATORS

Transcription

1 EB-- Exhibit D Page of DISTRIBUTION SYSTEM ELECTRIC INFRASTRUCTURE RELIABILITY PERFORMANCE INDICATORS FIVE-YEAR HISTORICAL RELIABILITY PERFORMANCE THESL tracks System Average Interruption Frequency Index ( SAIFI ), System Average Interruption Duration Index ( SAIDI ), and Customer Average Interruption Duration Index ( CAIDI ) in the following ways: Including all events Excluding Major Event Days ( MEDs ) Excluding MEDs and Loss of Supply In addition to these performance indicators, THESL also provides a breakdown of Scheduled Outages in each of the five years. Similar to Loss of Supply and MEDs, Scheduled Outages affect the system adversely but do not represent the true state of THESL s distribution system. FIVE-YEAR HISTORICAL RELIABILITY PERFORMANCE The following Figures and demonstrate total number of Customers Interrupted ( CI ) and total Customer Hours Interrupted ( CHI ) for the system over the past five years, respectively. The four CI and CHI values for each year represent the effects of MEDs, Loss of Supply and Scheduled Outages relative to all other type of system outages.

2 EB-- Exhibit D Page of Figure : System Level CI Figure : System Level CHI

3 EB-- Exhibit D Page of MAJOR EVENT DAYS An MED is defined by standard P/D of the Institute of Electrical and Electronics Engineers ( IEEE ) as events that are beyond the design and/or operational limits of a utility. The removal of MEDs allows a utility to normalize its reliability data to make trending and goal setting possible. An example of a normalizing application was the OEB-allowed modification of reliability data, in light of the August, provincial blackout. MEDs experienced by THESL since are shown in Table below: Table : Major Event Days Date Description Category SAIDI August, Blackout Loss of Supply days September, Hurricane Isabel Adverse Weather. minutes July, Loss of Supply to Esplanade TS Loss of Supply. minutes August, Major Storm (Thunderstorm) Adverse Weather. minutes August, Major Storm (Thunderstorm) Adverse Weather. minutes July, Major Storm (Thunderstorm) Adverse Weather. minutes August, Loss of Supply to Scarborough TS Loss of Supply. minutes March, Major Ice Storm Adverse Weather. minutes June, Major Storm (Thunderstorm) Adverse Weather. minutes January, Dufferin TS Flooding Adverse Environment. minutes April, Major Storm (Thunderstorm) Adverse Weather. minutes August, Major Storm (Thunderstorm) Adverse Weather. minutes August, Major Storm (Thunderstorm) Adverse Weather. minutes July, Loss of Supply to Manby TS Loss of Supply. minutes Figure demonstrates the contribution of the different categories of MEDs over the past five years:

4 EB-- Exhibit D Page of Figure : SAIDI Impact from MEDs MEDs have played a large part in contributing to system CI and CHI in all years as shown by the following Figures and. The exception is in which THESL did not experience any MEDs. As evident from the graph, adverse weather outages contribute most to THESL MEDs; such outages are largely attributable to the overhead ( OH ) system. THESL capital plan initiatives will help reduce the impact of weather related outages by re-designing the OH system over the past five years. Although adverse weather has the greatest contribution overall, the largest single event, as seen in the adverse environment cause code, was a total station outage due to flooding at Dufferin TS in.

5 EB-- Exhibit D Page of System CI due to MED, LOS, and Planned Outages Customers Interrupted,,,,,,,,,, MED CI Loss of Supply CI Planned Outages CI,,,,,,,,,,,,,, Total,,, Figure : System CI due to Major Event Days, Loss of Supply and Planned Outages LOSS OF SUPPLY Loss of Supply ( LoS ) events continue to have a significant impact on the overall reliability of the system. In, a total of LoS events affected the system while in, such events occurred. The top three events in terms of CI accounted for percent of the total CI due to LoS in. Similarly, the top three LoS events in terms of CHI accounted for percent of the total CHI due to LoS in. These do not include the MED on July,. Figures and show the CI and CHI from the past five years due to the LoS. On a system level, LoS can affect up to ten percent of the SAIDI and SAIFI (excluding MEDs). While THESL does not have direct control over such events, it can reduce the impact of LoS outages through initiatives such as stations ties or feeder

6 EB-- Exhibit D Page of automation. The overall performance of the THESL system is strongly impacted by changes in LoS year-over-year, but THESL has no direct control over LoS. By excluding this factor, THESL is able to monitor and asses the true state of its distribution system. System CHI due to MED, LOS, and Planned Outages Customer Hours Interrupted,,,,,,,, MED CHI Loss of Supply CHI Planned Outages CHI,,,,,,,,,,,,,,, Total,,,, Figure : System CHI due to Major Event Days, Loss of Supply and Planned Outages SCHEDULED OUTAGES Given the deteriorating asset condition of THESL s system, more Scheduled Outages have been required year-over-year since. These outages improve the reliability of the system in a planned manner. Figures and illustrate the impact of such outages on CI and CHI, respectively.

7 EB-- Exhibit D Page of From to, THESL saw a significant increase in the number of scheduled outages that is reflected proportionally in the CI and CHI for this cause code. In, Scheduled Outages contributed. percent to SAIFI and. percent to SAIDI. The increase in the number of Scheduled Outages is required to replace ageing infrastructure. Although this increased capital work has reduced the overall reliability of the system in the short-term, the long-term improvements outweigh the short-term impact. SYSTEM RELIABILITY EXCLUDING LOSS OF SUPPLY, MAJOR EVENT DAYS AND SCHEDULED OUTAGES THESL has very limited control over Major Event Days and Loss of Supply events. As a result, the impact of these factors will be excluded from further analysis of the overall system performance. In addition, because Scheduled Outages are required in order to replace assets that are at end-of-life, THESL will also be excluding the reliability impact of these planned outages from the analysis of the system performance. Taking into account Adverse Environment, Adverse Weather, Defective Equipment, Foreign Interference, Human Element, Lightning, Tree Contacts, Unknown and excluding MEDs, LoS and Scheduled Outages, the true performance of assets that were planned to remain in service for each year can be further analyzed. Figures,, and show the SAIFI, SAIDI, and CAIDI performance indicators of the system, respectively, excluding the following: MEDs, LoS events and Scheduled Outages.

8 EB-- Exhibit D Page of System SAIFI System SAIFI..... Figure : System SAIFI Excluding MEDs, LoS and Scheduled Outages System SAIDI System SAIDI..... Figure : System SAIDI Excluding MEDs, LoS and Scheduled Outages

9 EB-- Exhibit D Page of CAIDI System CAIDI System CAIDI..... Figure : System CAIDI Excluding MEDs, LoS and Scheduled Outages In, system SAIFI remained at the same level as, while system SAIDI saw improvement. The SAIDI improvement is due to lower CHI from defective equipment and foreign interference related outages. Since CAIDI is defined as the ratio of SAIFI to SAIDI, the SAIDI improvement led to the system CAIDI improvement for the year. CAUSE CODE ANALYSIS THESL tracks causes of service interruptions using the ten primary cause codes, as specified in Table. of the Electricity Distribution Rate Handbook. Figures and show the reliability performance for CI and CHI from to for the ten primary cause codes respectively.

10 EB-- Exhibit D Page of Figure : System CI Cause Code Breakdown (Excluding MEDs)

11 EB-- Exhibit D Page of Figure : System CHI Cause Code Breakdown (Excluding MEDs) Table : SAIFI and SAIDI Contributions by Cause Codes Cause Code Contribution % to SAIFI Contribution % to SAIDI Defective Equipment.. *Loss of Supply.. Adverse Weather.. Unknown.. Foreign Interference.. Tree Contacts.. *Scheduled Outage.. Human Element.. Lightning.. Adverse Environment.. *Excluded from further analysis in this document to reflect the true status of the system.

12 EB-- Exhibit D Page of In, Defective Equipment continued to be the main contributor to SAIFI and SAIDI, at. percent and. percent respectively. Adverse Weather, which contributed to. percent of SAIFI and. percent of SAIDI in, had a far greater impact on system reliability in compared to. Foreign Interference accounted for. percent of system SAIFI and. percent of system SAIDI, yet improved from levels. Tree Contacts resulted in. percent of system SAIFI and. percent of system SAIDI. When reviewing each cause code year over year, it can be seen that Defective Equipment and Foreign Interference with addition of year are showing an improving trend while Scheduled Outages, Human Element, Adverse Weather and Tree Contacts are showing deterioration. In order to provide a better understand of reliability trend, THESL has provided an in depth analysis of each of these cause codes. DEFECTIVE EQUIPMENT ANALYSIS The following graphs further categorize Defective Equipment CI and CHI contribution by distinguishing between the following four different categories: Underground Equipment ( U/G Equipment ) Overhead Equipment ( O/H Equipment ) Station Equipment ( STN Equipment ) Other Equipment ( OTHER Equipment ) Figure and show the CI and CHI breakdown for each category of Defective Equipment excluding MEDs.

13 EB-- Exhibit D Page of Defective Equipment: CI Contribution Customers Interrupted,,,,,,,, Underground Equipment Overhead Equipment Station Equipment Other Equipment,,,,,,,,,,,,,,,,,,,, Figure : Defective Equipment Breakdown (CI)

14 EB-- Exhibit D Page of Defective Equipment: CHI Contribution, Customers Hours Interrupted,,,,,, Underground Equipment Overhead Equipment Station Equipment Other Equipment,,,,,,,,,,,,,,,,,,,, Figure : Defective Equipment Breakdown (CHI) As can be seen in Figures and, the largest contributors to Defective Equipment CI and CHI in were Defective Overhead and Underground Equipment. In, Overhead Equipment failures counted for percent of the CI due to defective equipment, while counting for percent of the CHI contribution. In comparison, in, overhead equipment counted for percent of the CI and percent of the CHI contribution. This shows that over the years, the overhead system has become a major contributor to the decline of system reliability. Defective Overhead Equipment In, Overhead Defective Equipment accounted for about percent of system-wide SAIFI and about percent of system wide SAIDI. Defective Overhead Equipment has

15 EB-- Exhibit D Page of had a significant impact on overall system reliability and has been deteriorating over the past five years. In general, a significant trend upwards is seen in defective Overhead Equipment failures. More specifically, overhead switches, insulators, and lighting arrestor failures have had increasing contributions to system reliability. These causes account for percent of the CI and percent CHI of the total Overhead Equipment failures in. In addition to these assets, Overhead Conductors are another major contributor to Equipment CI and CHI. Transformers, while not a significant contributor to CI and CHI, have the highest number of failures in the Overhead system with percent of those due to CSP transformers. The number of outages year-over-year is reflected in defective Overhead Equipment CI and CHI. The overhead portion is beginning to show a deteriorating trend over the past three years. From a SAIDI perspective, overhead outages account for percent, percent and percent of the Defective Equipment-related outages from to, and percent, percent and percent of the Defective Equipment-related outages in SAIFI from to, respectively. To further analyze the causes for the increase in CI and CHI of the overhead system, major contributors for CI and CHI across the system are further broken down by individual components. Figures,, and portray the individual overhead system components contribution to CI and CHI, as well as number of outages due to overhead equipment failure. As evidenced by these figures, the major contributors to overhead equipment failure have been deteriorating in the past five years.

16 EB-- Exhibit D Page of Defective OH Equipment: CI Contribution Customers Interrupted,,,,,, Switch Insulator Conductor Lightning Arrestor Transformers,,,,,,,,,,,,,,,,,,,,,,,,, Figure : Overhead Defective Equipment Major Contributors (CI) Defective OH Equipment: CHI Contribution Customer Hours Interrupted,,,,,,,, Switch Insulator Conductor Lightning Arrestor Transformers,,,,,,,,,,,,,,,,,,,,,,,,, Figure : Overhead Defective Equipment Major Contributors (CHI)

17 EB-- Exhibit D Page of Defective OH Equipment: Number of Outages Number of Outages Switch Insulator Conductor Lightning Arrestor Transformers Figure : Overhead Defective Equipment Major Contributors (Outages)

18 EB-- Exhibit D Page of Defective OH Equipment: CI Per Outage Customers Interrupted,,,,, Switch Insulator Conductor Lightning Arrestor Transformers,,,,,,, Figure : CI Impact per Outage from Overhead Equipment Defective OH Equipment: CHI per Outage Customer Hours Interrupted,,,, Switch Insulator Conductor Lightning Arrestor Transformers,,, Figure : CHI Impact per Outage from Overhead Equipment

19 EB-- Exhibit D Page of Insulators The five-year trend for insulators shows a large increase in CI and CHI. Insulators account for percent of the overhead system CHI and percent of the overhead system CI in. Porcelain-type insulators account for approximately percent of the insulator CI and CHI. Although CI and CHI are on the rise, when looking at the number of interruptions, it can be seen that the overall failures in the distribution system has shown a slight improvement from, but a deteriorating trend from. This is due to the proactive insulator replacement in projects. As evidenced by the figures above, while insulator failures are lower in frequency compared to other major overhead assets, such failures have the greatest impact on system reliability. In, an insulator failure on average led to customers interrupted. THESL intends to continue phasing out the porcelain insulators across the system and replacing them with the more reliable polymeric type insulators. Conductors Overhead conductor failures have been trending upwards over the past five years as THESL s overhead assets age. Overhead conductors are addressed as part of overhead rebuild projects. Lightning Arrestors Lightning Arrestors cause about percent of the Overhead Defective Equipment CI and CHI. The system has experienced a decrease in number of outages from this asset class over the past two years as the oldest and highest failure risk Lighting Arrestors have been replaced. However, the five-year CI and CHI trends have been increasing. Overhead Switches From the CI and CHI figures, it can be seen that the CI and CHI closely mirror the number of outages year-over-year. As shown in Figures and, the CI and CHI per

20 EB-- Exhibit D Page of Switch failure have steadily increased to, customers per outage with a total duration of hours per outage. THESL currently plans on addressing the impact of switch failures and restoration time by increasing the number of switches and automated switches in the system. This approach allows the affected locations to be isolated from the system and the rest of the feeder to be restored. As more automated switches are installed, the CI and CHI will improve. Defective Underground Equipment Even though Defective Underground Equipment has shown marked improvement in both CI and CHI contribution over the last five years, it remains a significant contributor to overall system SAIFI and SAIDI. In, Defective Underground Equipment accounted for about percent of system wide SAIFI and about percent of system wide SAIDI. Figures and portray the CI and CHI contributions due to underground equipment failure.

21 EB-- Exhibit D Page of Defective U/G Equipment: CI Contribution Customers Interrupted,,,,,,,,,,,,, Primary Cable & Joints Submersible Transformer Elbow Terminator Switchgear All other types,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, Figure : Underground Defective Equipment Major Contributors (CI)

22 EB-- Exhibit D Page of Figure : Underground Defective Equipment Major Contributors (CHI)

23 EB-- Exhibit D Page of Defective UG Equipment: Number of Outages Number of Outages Primary Cable & Joints Submersible Transformer Elbow Terminator Switchgear All Other Types Figure : Underground Defective Equipment Major Contributors (Outages)

24 EB-- Exhibit D Page of Defective UG Equipment: CI per Outage Customers Interrupted,,,,,, Primary Cable & Joints Submersible Transformer Elbow Terminator Switchgear All Other Types,,,,,, Figure : CI Impact per Outage from Underground Equipment

25 EB-- Exhibit D Page of Defective UG Equipment: CHI per Outage Customers Hours Interrupted,, Primary Cable & Joints Submersible Transformer Elbow Terminator Switchgear All Other Types, Figure : CHI impact per Outage from Underground Equipment Primary Cable As can be seen in Figures and, defective primary cable remains the largest contributing factor to CI and CHI for defective underground equipment. This has a significant overall impact on system reliability. In, defective primary cable contributed percent to overall system SAIFI and percent to overall system SAIDI, and percent to the Underground Defective Equipment category SAIFI and SAIDI. As is evident in Figures and, the average number of customers interrupted per failure is with an average total time of hours. A significant portion of the primary cable faults occur on direct-buried cable, a legacy standard, most of which is beyond the end of its useful life. Capital investments in this asset class have been initiated to replace directburied primary cable with current standard cable in concrete encased duct. This

26 EB-- Exhibit D Page of investment has had favorable impacts on the overall system reliability, and as a result, THESL plans to continue investing in the direct-buried primary cable removal project. Both CI and CHI attributable to primary cable have declined since the introduction of this project in. From to, a total reduction of percent to the CI and percent o the CHI has been realized. Submersible Transformers and Elbows In the second largest contributor to Defective Underground Equipment was submersible transformers accounting for seven percent of Defective Underground Equipment CI and ten percent of Defective Underground Equipment CHI. Due to capital investment in this asset class over the last number of years, the general performance trend is slightly improving. When legacy submersible transformers are replaced with standard switchable ones, the elbows are also replaced because they are at the end of their useful lives. The significant number of submersible transformers replaced over the last few years has had a very favorable impact on the SAIFI and SAIDI contribution of elbows. This trend can be seen in Figures and as elbow-related outages have decreased. Switchgear As can be seen from Figures and, switchgear is also a significant contributor to Defective Underground Equipment. The general trend of CI and CHI contribution from defective switchgear over the last five years has slightly improved. In the past two years, THESL has observed a decrease in the CI and CHI impact to the system from switchgear. As evident from Figures and, customers are interrupted with each failure on average with a total duration of hours. Part of this reliability improvement can be attributed to increased maintenance spending on the inspection and cleaning of padmounted switchgear. Capital expenditures are proposed in the ten-year plan to phase out air insulated pad-mounted switchgear and replace it with sealed-type switch gear. One such example of a sealed-type switchgear is the SF pad-mounted switchgear. The

27 EB-- Exhibit D Page of switch contains SF gas inside of the sealed switchgear housing. This eliminates the contamination from environmental factors that results in the failure of air-insulated switchgear. Human Element Though Human Element has the smallest impact of all the cause codes, the CHI has been showing an upward trend over the past five years and with the exception of, the CI has also been showing a similar trend. Human Element is caused when work by THESL or THESL contractors creates an outage. From to, the significant increase to Scheduled Outages closely mirrors the increase in Human Element events. Like Scheduled Outages, Human Element is directly impacted by the capital program and is closely monitored by THESL as it involves employee safety. Customers Interrupted Human Element CI,,,,, CI,,,,, Figure : Human Element Contribution (CI)

28 EB-- Exhibit D Page of Customers Hours Interrupted Human Element CHI,,,,,, CHI,,,,, Figure : Human Element Contribution (CHI) Adverse Weather In, Adverse Weather contributed towards. percent of the system SAIFI and. percent of the system SAIDI. The number of outages due to Adverse Weather has been trending down over the past five years, but the impact from Adverse Weather over these years has increased. Figures, and show the trend of Adverse Weather outages over the past five years.

29 EB-- Exhibit D Page of, ADVERSE WEATHER CI, Customers Interrupted,,,,, Adverse Weather,,,,, Figure : Adverse Weather Contribution (CHI) Customer Hours Interrupted,,,,,,,,,, Adverse Weather CHI Adverse Weather,,,,, Figure : Adverse Weather Contribution (CHI)

30 EB-- Exhibit D Page of Number of Adverse Weather Outages Adverse Weather Figure : Adverse Weather Contribution (Outages) CI due to adverse weather outages has shown an inconsistent yet upward trend over the past five years. Storm hardening and conversion of overhead plant to underground will reduce the vulnerability of the overhead system to adverse weather conditions. CHI due to adverse weather has also been trending up over the last five years. Introduction of Fault Current Indicators ( FCIs ) into the system will help localize faults and reduce outage restoration times. Foreign Interference Foreign Interference continues to be a significant contributor to system reliability as shown in Figures and. A downward trend of foreign interference CI and CHI contributing. percent to system SAIFI and. percent to system SAIDI, was shown in. In the Foreign Interference category, THESL has some measure of control over animal contact, where the installation of animal guards has led to a reduction in outages.

31 EB-- Exhibit D Page of Figure : Foreign Interference Breakdown (CI)

32 EB-- Exhibit D Page of Figure : Foreign Interference Breakdown (CHI) Tree Contacts In, Tree Contacts had a contribution of. percent to SAIFI and. percent to SAIDI. Tree Contacts can be occur in adverse or normal weather conditions or through brush contact. Figures,, and provide a breakdown of the three types of Tree Contact outages. From Figure, it can be seen that CI due to Tree Contact has remained relatively stable over the past years while Figure shows the CHI increasing from to. Figures and further breaks down the Tree Contact cause code into Adverse Weather, Normal Weather and Brush Contact. There is a significant increase in the Adverse Weather CI and CHI when compared to. When comparing Figures and

33 EB-- Exhibit D Page of, it can be seen that the average number of customers interrupted has remained around, customers per Adverse Weather interruption over the past five years while the duration has increased to, hours. When compared to Defective Equipment CI and CHI per outage, Adverse Weather Tree Contacts would rank as one of the top categories. Tree Contacts: CI Breakdown Customers Interrupted,,,,,, Adverse Weather Normal Weather Brush Contacts,,,,,,,,,,,,,,, Figure : Tree Contact Breakdown (CI)

34 EB-- Exhibit D Page of Tree Contacts: CHI Breakdown Customers Hours Interrupted,,,,,, Adverse Weather Normal Weather Brush Contacts,,,,,,,,,,,,,,, Figure : Tree Contact Breakdown (CHI) Tree Contacts: Number of Outages Number of Outages Adverse Weather Normal Weather Brush Contacts Figure : Tree Contact Breakdown (Outages)

35 EB-- Exhibit D Page of Tree Contacts: CI Per Event Customers Interrupted,, Adverse Weather Normal Weather Brush Contacts,,,,,,, Figure : CI per Tree Contact Event Adverse Weather interruptions are caused by severe storms or high wind conditions. During these times, tree branches can break off and fall onto THESL conductors. From to, THESL has observed,,, and unique days respectively in which Adverse Weather Tree Contacts occurred. A unique Adverse Weather day is any one day in which one or more Adverse Weather Tree Contact takes place. Taking the total number of Adverse Weather Tree Contact interruptions and dividing it by the total number of unique days, will result in the number of Tree Contact outages per Adverse Weather day. This is represented in Figure below.

36 EB-- Exhibit D Page of Tree Contacts: CHI Per Event Customers Hours Interrupted,,,,, Adverse Weather Normal Weather Brush Contacts,,, Figure : CHI per Tree Contact Event

37 EB-- Exhibit D Page of Outages per Adverse Weather Day... Outages.... Outages per Adverse Weather Day..... Figure : Outages per Adverse Weather Day From Figure, it can be seen that even though in THESL had less storm days than any of the previous years, when comparing the Average Outages per Adverse Weather day, there is a significant increase. Though there were fewer days in which Adverse Weather Tree Contacts occurred in, the storms were more severe and caused more damage to the system. CHI is an indication of how quickly THESL can respond to outages across the system. It can be seen from Figure that the CHI due to Adverse Weather increased significantly in. This is due to the concentration of the events occurring simultaneously and adversely affecting THESL response time.