Outage cost oriented maintenance strategies of outgoing feeders in transmission systems

The near-perfect performance of the 380 kV transmission network is one of the major reasons in the highly reliable electrical energy supply in Germany. But due to the sustained cost pressures for transmission system operators the operational expenditures must be reduced in order remaining competitive. A changeover from a usual time-oriented to a risk-based maintenance is more and more often on the agenda. In this paper a method is presented which generates risk-based maintenance strategies for overhead lines and their connecting outgoing feeder in a German 380 kV extra high voltage transmission system with the target operative risk costs reduction. The origin of this strategy is the determination of the importance of the different routes for an unrestricted functionality of the transmission system. This method takes into account standard as well as log-normal distributions of age-dependent reliability behavior of the assets, bay configurations and different load conditions of the transmission network in the 380 kV level. Furthermore a Monte Carlo simulation is used for creating combinations of financial and technical data. Finally, an extreme clipping of extraordinary combinations is performed with the value at risk method.