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Utility develops repair/refurbish/replace strategy using innovative risk-based methodologies.
Utilities are increasingly operating transformers up to and beyond their expected life spans. Asset managers are diagnosing and monitoring the condition of critical and problematic units, and then ranking the transformers by condition to deal in the near-term with the units that affect utility operations the most. However, from regulatory and business planning perspectives, a longer-term view on operating and capital investment is necessary. Developing a repair/refurbish/replace management strategy for significantly aged populations with a rational basis for the strategy is a critical need.
This type of strategy requires that asset managers relate the effect of available options on projected failure/replacement rates and their associated costs and impacts. In response to this need, utilities have adopted the assumption that failure/replacement rates experienced in the past will continue in the future. If utilities had a constant distribution of transformer ages, and if the age distribution was in the flat portion of the "bathtub curve," this would be a valid approach.
In practice, however, many utilities have demographic distributions displaying a bulge of units in the 40, 50 and older age categories, which are at the back end of the bathtub curve where failures increase rapidly over time. As a result, new asset-management approaches are needed for the effective management of the "boomer" generation of aging transformers.
A new EPRI project surveyed utility practices and needs and identified important asset-management case studies. The project formulated a new risk-based methodology that could be used for solutions in these types of business case studies.
Reviewing Existing Practices and Emerging Needs
Sample utility concerns and needs were addressed through a focused survey of leading utility managers. Of the surveyed managers, more than two-thirds were concerned with the adverse demographics of their transformer fleets. In view of these concerns, a significant portion of utilities are beginning to proactively replace transformers. Of the surveyed managers, two-thirds are increasingly using on-line diagnostic monitoring to assess transformer condition. The survey confirmed that most utilities use historic failure rate data to project future failure rates. As a result, utility managers are unanimous in their assessment that the development of improved methodologies for managing such transformer fleets is necessary. While utility managers agree that improved methodologies are...