The Portuguese Transmission System Operator [TSO] launched a long term enterprise for developing a risk based methodology to optimise Overhead Line [OHL] lifetime and maintenance costs, based on asset information, inspection, maintenance and third party data. The methodology must provide next-day and next-year risk estimates for operation and maintenance, respectively.
The authors propose combining heterogeneous information into a probabilistic model that may be used to find maintenance policies optimizing the trade-off between cost reduction and higher quality of service. It leverages field data from helicopter inspections, dispatch event records and third party data. Such approach is most suitable for OHL risk analysis and estimation, since OHL spreads across heterogeneous territories and are subject to diverse environmental factors.
The procedure considers the interaction between the OHL and its space-time context, thus departing from the more traditional single component view towards a system analysis. To cope with the heterogeneity covered by transmission OHL, the model’s spatial resolution is data driven, varying from a Portuguese geographic administrative (larger) unit to the physical span (smaller), according to how data is geographically framed, while the time unit may range from seconds to years, thus satisfying the diverse time-scope requirements of the undergoing work promoted by REN, the Portuguese TSO.
The methodology is generic enough to be applied to different contingencies and different time scopes. The paper shows an example of risk-based maintenance considering the reliability of the OHL due to bushfires, fog, and obstacles collisions, like trees.