1 Managing Distribution System Reliability at Southern California Edison Robert Tucker Thach “Nicholas” Duong Roger Lee OIR R Workshop May 26 & 27, 2015

2 Current Circuit-level Reliability Management Programs Current Distribution System Maintenance Programs Reliability Refresher Discussion of Tools Assessment of Total System Need Allocation of Funding Among 8 SCE Regions Worst Circuit Rehabilitation Program: Identifying the Worst Circuits Identifying Work on Each Circuit Documentation Fast Track WCR Program: Circuit RADAR Challenges: Volatility / Probability Balancing Circuit vs. System Performance Cost-effectiveness Overview

3 Current Circuit-level Reliability Management Programs Southern California Edison's various asset management programs can be divided into three categories based on their drivers and anticipated impacts to system reliability metrics such as SAIDI, SAIFI and MAIFI. The first category of programs is designed to manage system and circuit reliability utilizing rigorous mathematical modeling which can quantitatively predict future reliability as a function of various types and levels of infrastructure replacements and circuit modifications. The primary program in this category is the Worst Circuit Rehabilitation (WCR) program which focuses investments on poorly performing distribution circuits. Programs in the second category are also designed to manage system and circuit reliability but employ less rigorous analytical methods. For many of these programs, reliability benefits are difficult to quantify with precision at this time. Some of these programs have been in place at SCE for years, such as the Substation Infrastructure Replacement program, the Underground Oil Switch Replacement program, the Capacitor Bank replacement program, and the Automatic Recloser Replacement program. Other programs have been initiated by SCE very recently, such as the Cable Testing program, the Cable Injection program, and the Overhead Conductor Program. The third category includes programs which are designed to address problems unrelated to in-service failures of electrical equipment but which may generate reliability benefits. These programs are not explicitly designed for targeted improvements in system reliability metrics, and they are not expected to have a significant impact on system reliability performance. Examples of these programs include the Load Growth program, the 4 kV cutover programs, the deteriorated pole replacement program, and the Deteriorated Vault and Manhole Program.

4 Current Distribution System Maintenance Programs SCE’s Distribution Inspection and Maintenance Program (DIMP) pursues public and worker safety and regulatory compliance by completing scheduled Detailed Inspections and Grid Patrols of the distribution system in conformity with the California Public Utilities Commission's (CPUC) General Order (G.O.) 165, and in accordance with G.O. 95, G.O. 128, SCE standards, and good utility practice. General Order 165 was enacted on March 31, 1997 to establish maximum time intervals of inspection frequency of all electric distribution facilities within the jurisdiction of the CPUC. The basic premise of G.O. 165 is that all distribution assets must be patrolled every year for safety and reliability issues and the identification of significant G.O. 95 and 128 discrepancies. General Order 165 also requires these same assets to have a close up detailed inspection every 5 years (or less) to identify safety and reliability issues as well as all G.O. 95 and 128 discrepancies.

5 Current Circuit-level Reliability Management Programs Current Distribution System Maintenance Programs Reliability Refresher Discussion of Tools Assessment of Total System Need Allocation of Funding Among 8 SCE Regions Worst Circuit Rehabilitation Program: Identifying the Worst Circuits Identifying Work on Each Circuit Documentation Fast Track WCR Program: Circuit RADAR Challenges: Volatility / Probability Balancing Circuit vs. System Performance Cost-effectiveness

6 Reliability Refresher The challenge to SCE’s reliability comes primarily from in-service equipment failures.

7 This challenge will increase because the system is continuing to age…and …

8 … the probability of failure increases, exponentially, with age.

9 The volume of an infrastructure type wearing out each year will increase until the average age of that population plateaus. Whether replacements are effected reactively or preemptively, as well as circuit design and crew response, will affect system and circuit reliability.

10 Current Circuit-level Reliability Management Programs Current Distribution System Maintenance Programs Reliability Refresher Discussion of Tools Assessment of Total System Need Allocation of Funding Among 8 SCE Regions Worst Circuit Rehabilitation Program: Identifying the Worst Circuits Identifying Work on Each Circuit Documentation Fast Track WCR Program: Circuit RADAR Challenges: Volatility / Probability Balancing Circuit vs. System Performance Cost-effectiveness

11 Risk assessment tools (CYME-RAM & in-house tools) can be used to assess circuit SAIDI/SAIFI/MAIFI as a function of design and P(f|age) of circuit elements. Circuit modeling

12 Weibull curves are developed to determine P( f | age)

13 Circuit reliability modeling ( highly labor intensive ) can quantitatively assess benefits Analytical assessments inform SCE’s guidelines which are used to identify remediation work which is both effective and cost-effective.

Circuit modifications such as Branch Line Fusing (BLF) and Fault Indicators (FI) are the most cost-effective investment in system reliability Initial layers of circuit automation are, relatively speaking, the next most cost- effective investment in system reliability  Note: Increasing layers of automation beyond initial layers will yield diminishing returns on investment After FIs, BLFs and automation, replacement of aged cable is the next most cost-effective investment in system reliability  Note: Replacement of younger cable will yield rapidly diminishing returns on investment Compared to the top three categories above, replacement of other distribution infrastructure (i.e. service transformers, poles, underground vaults, secondary services, etc…) is typically less cost-effective as an investment in system reliability  However, such scope elements are often justified for other reasons: safety issues, compliance requirements, operational flexibility, specific customer issues, opportunity work, etc… 14 Analysis-informed guidelines for designing WCR projects

15 Current Circuit-level Reliability Management Programs Current Distribution System Maintenance Programs Reliability Refresher Discussion of Tools Assessment of Total System Need Allocation of Funding Among 8 SCE Regions Worst Circuit Rehabilitation Program: Identifying the Worst Circuits Identifying Work on Each Circuit Documentation Fast Track WCR Program: Circuit RADAR Challenges: Volatility / Probability Balancing Circuit vs. System Performance Cost-effectiveness

16 Conclusion: Without a program to address infrastructure aging, system SAIDI (and SAIFI) would increase significantly. Assessing the consequence of inaction

17 “500 IR” = Program of replacing 500 miles of the most risk-sensitive cable + cost-effective mitigation enhancements on our “worst-performing” circuits Options for various levels of reliability-focused infrastructure investment

18 Having the established the annual system need for investment, the next step is to maximize the return on that investment. Funding to address total system need is allocated among the 8 Regions according to % contribution to System SAIDI and SAIFI Allocation of funding among 8 Regions

19 Within each Region, circuits are prioritized under multiple categories of reliability performance.

20 Specific Example: Octane 16 kV (scoped for 2016 project)

21 Data Source: Outage Data Records Management (ODRM) The outage history is researched on each targeted circuit.

22 Rehabilitation work scopes are developed using risk-informed guidelines, outage histories, and circuit design and component age. Building Remediation Work Scopes

23 In summary, the WCR process is systematic and objective

24 The WCR annual report records the method and results.

25 For each “worst circuit”, an explanation of its selection and its disposition, and a description of its remediation are documented.

26 Current Circuit-level Reliability Management Programs Current Distribution System Maintenance Programs Reliability Refresher Discussion of Tools Assessment of Total System Need Allocation of Funding Among 8 SCE Regions Worst Circuit Rehabilitation Program: Identifying the Worst Circuits Identifying Work on Each Circuit Documentation Fast Track WCR Program: Circuit RADAR Challenges: Volatility / Probability Balancing Circuit vs. System Performance Cost-effectiveness

27 Rolling 12-Month Circuit Performance Report (RADAR) ► Results in awareness of circuit performance and “Fast Track,” (i.e., expedited), WCR projects.

28 Current Circuit-level Reliability Management Programs Current Distribution System Maintenance Programs Reliability Refresher Discussion of Tools Assessment of Total System Need Allocation of Funding Among 8 SCE Regions Worst Circuit Rehabilitation Program: Identifying the Worst Circuits Identifying Work on Each Circuit Documentation Fast Track WCR Program: Circuit RADAR Challenges: Volatility / Probability Balancing Circuit vs. System Performance Cost-effectiveness

29 Circuit performance can be highly volatile and difficult to predict

30

31 30 Year Average CMI (without & with WCR) – Alfredo 16 kV WCR Yearly CMI with WCR (4 simulation results shown) Monte Carlo simulations vs. Calculated Average Forecasts Remediation projects should focus on long term average benefits. The nature of probability tells us that no remediation project on any individual circuit can guaranty short term improvements.

32 “System” ≡ Because remediation work on each circuit varies in benefit/cost, “gold plating” a circuit penalizes the system. The “system” benefits more when remediation resources are distributed across multiple circuits than when resources are focused on one circuit. 123 How much investment to make on any given circuit?

33 Cost-effectiveness

34 Current Circuit-level Reliability Management Programs Current Distribution System Maintenance Programs Reliability Refresher Discussion of Tools Assessment of Total System Need Allocation of Funding Among 8 SCE Regions Worst Circuit Rehabilitation Program: Identifying the Worst Circuits Identifying Work on Each Circuit Documentation Fast Track WCR Program: Circuit RADAR Challenges: Volatility / Probability Balancing Circuit vs. System Performance Cost-effectiveness Summary