1. Barcelona, May 13, 2003 ASSET MANAGEMENT Development of new approaches Gerd Balzer Darmstadt University of Technology TU Darmstadt Institute of Electrical Power Systems

2. Overview -Introduction -Age profile of equipment -Consequence of the ageing process -Maintenance strategies -Reliability-Centered Maintenance (RCM) -Example: Assessment of substations -Renovation strategy with Fuzzy-Logic -Proposal for a Risk-Assessment -Conclusion TU Darmstadt Institute of Electrical Power Systems

3. Component level System level Corporate level 1: Maintenance and diagnostic evaluation scenario search and evaluation of effectiveness & usability 2: Economical evaluation of scenarios, creation of maintenance strategies, calculation of non-availability of energy 3: Risk management, selection of optimal scenario, and optimal strategy Technical information (on assets) Economical information (on assets) Technical information (on grid) Economical information (on business) Sociological information Decision Asset Management decision process (Cigre WG 23/39)

4. Age distribution for m.v. equipment (VDEW-statistic, Germany) TU Darmstadt Institute of Electrical Power Systems Year of installation Population

5. Age distribution for substations (AIS) (Cigre Brochure no. 176) TU Darmstadt Institute of Electrical Power Systems

6. Installations and replacement distribution (substation equipment, Cigre Brochure no. 176) TU Darmstadt Institute of Electrical Power Systems

7. Consequence of ageing Falling reliability of the system is a major consequence of the ageing process: -decision to delay asset replacement -an attempt to recover by increasing asset replacement at a later stage Lower availability and further fault outages TU Darmstadt Institute of Electrical Power Systems

8. The spiral of decline TU Darmstadt Institute of Electrical Power Systems

9. In general the Reliability Centered Maintenance (RCM) strategy for substation can be used in two different ways: - substation approach:Which equipment/components influence the function of the complete substation (Failure Mode Effect Analysis, FMEA) - system approach:Which substations influence the availability and the performance of the system (reliability calculation and assessment of the non-delivered energy, risk management) The report deals with the system approach TU Darmstadt Institute of Electrical Power Systems

10. The system approach solves the main task of an utility, due to the financial constraints and to receive a ranking of substations concerning the yearly budget: which substation has to be maintained first, second, and so on. TU Darmstadt Institute of Electrical Power Systems

11. Different types of maintenance strategies Condition-based Reliability-centered Time-based Corrective TU Darmstadt Institute of Electrical Power Systems

12. Corrective or Reactive Maintenance -repair or replacement after a fault -no influence on the time of failure -availability of the substation depends on the reliability of the single equipment - lowest maintenance costs without consideration of further expense TU Darmstadt Institute of Electrical Power Systems

13. Time-Based or Scheduled Maintenance -predefined inspections (time period) -replacement after a fixed life time -high availability -no use of the equipment up to the end of the life time - most expensive maintenance strategy TU Darmstadt Institute of Electrical Power Systems

14. Condition-Based or Predictive Maintenance -inspection or replacement due to the condition -all identical equipment are treated in the same manner TU Darmstadt Institute of Electrical Power Systems

15. Reliability-Centered Maintenance -inspection or replacement due to the technical condition -importance of the equipment for the network - optimal maintenance strategy TU Darmstadt Institute of Electrical Power Systems

16. Maintenance Strategies CM Corrective Maintenance yesno ? Maintenance activities for specific types of equipment ? noyes diagnostic CBM ConditionBased Maintenance TBM TimeBased Maintenance yesno ? RCM ReliabilityCentered Maintenance importance TU Darmstadt Institute of Electrical Power Systems

17. Procedure for maintenance planning (equipment) Index c condition of equipment Index i importance of equipment Maintenance strategy Index o overall index of equipment TU Darmstadt Institute of Electrical Power Systems

18. Procedure for maintenance planning (substation) Index i importance of substation Index o overall index of substation Index c condition of substation Circuit- breaker DisconnectorBayBuilding Protection & Control TU Darmstadt Institute of Electrical Power Systems

19. Interpretation of the assessment result ccondition of the equipment iimportance of the equipment TU Darmstadt Institute of Electrical Power Systems

20. Condition based maintenance ccondition of the equipment iimportance of the equipment TU Darmstadt Institute of Electrical Power Systems Replacement maintenance work inspections

21. Corrective, time-based or reliability centered maintenance ccondition of the equipmentiimportance of the equipment TU Darmstadt Institute of Electrical Power Systems inspections maintenance work replacement

22. Combination of different strategies ccondition of the equipment iimportance of the equipment TU Darmstadt Institute of Electrical Power Systems

23. Assessment of 40 secondary substations TU Darmstadt Institute of Electrical Power Systems 216/10 kV 1930 kV (four tower stations)

24. Equipment of the substations TU Darmstadt Institute of Electrical Power Systems -bay/type of construction -disconnector -load disconnector -transformer -building/tower

25. condition criteria for the assessment of bays -age; type -experiences; spare parts -safety aspects -partial discharge -pollution; humidity TU Darmstadt Institute of Electrical Power Systems

26. Assessment sheet of condition (equipment) e.g. substation bay TU Darmstadt Institute of Electrical Power Systems

27. Impact of equipment evaluationg the condition assessment in percentage Condition/%

28. Importance criteria for the assessment of secondary substations -kind of substation -maximum active power -customer -redundancy of the substation -hazard rate TU Darmstadt Institute of Electrical Power Systems

29. 0 20 40 60 80 100 0102030405060708090100 c i EHSN-307 SHAF-299 POHL-301 HOHA-601 TU Darmstadt Institute of Electrical Power Systems importance condition Final result of the assessment replacement A B C d dAdA dBdB dCdC service

30. TU Darmstadt Institute of Electrical Power Systems Basic principle of a decision-taking process using fuzzy logic Rules Fuzzification Defuzzification Knowledge processing Input values Output values

31. TU Darmstadt Institute of Electrical Power Systems Implementation of a maintenance strategy for substations

32. TU Darmstadt Institute of Electrical Power Systems Secondary substation condition 3: load/disconnector condition 1: bay Conditon 3 Conditon 1 result

33. TU Darmstadt Institute of Electrical Power Systems Time after commissioning resp. service Propability of outage of equipment Non delivered energy Result of reliability calculation Equipment model Outage costs Interruption costs - repair - interuption of supply - penalty and so on Risk-Management Szenario: - no action - service - renovation “sociological effects” Risk Assessment Maintenance costs - service - renovation

34. TU Darmstadt Institute of Electrical Power Systems Equipment model time after commissioning/last servive hazard rate T2T2 T1T1 T3T3 T4T4 2 1 4 I III II

35. TU Darmstadt Institute of Electrical Power Systems time after commissioning/last service probability of outages Probability of outages of the considered equipment 0.0 0.2 0.4 0.6 0.8 1.0 012345678910111213141516171819202122232425 T T +  t

36. TU Darmstadt Institute of Electrical Power Systems Probability of outages of the considered equipment Probability of outages time after commissioning/last service QQ QbQb 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 012345678910111213141516171819202122232425

37. Result of the assessment (substation): -comparison of different substations -determination, which equipment influences mainly the condition of the substation -what is the optimal order of substation to be maintained or replaced Decision:replacement of the equipment or new investment of the complete substation TU Darmstadt Institute of Electrical Power Systems

38. Advantage of a computer aided assessment: -fixing of compulsory criteria -determination of the ranking due to replacementor ranking -documentation of the decision TU Darmstadt Institute of Electrical Power Systems