Reliability-based improvement of life-cycle maintenance and replacement strategies in transmission systems using ant colony optimization

Due to the competition at the regulated energy market, transmission system operators want to save expenditures. Maintaining and replacing assets cause a part of expenditures at a transmission system. By including reliability calculation at the determination of maintenance and replacement strategies, expenditures can be saved without decreasing the availability of the grid. In this contribution, ant colony optimization performs a reliability-based prioritization of assets for maintenance and replacement during a life-cycle period. The method is able to improve either the expenditures for maintenance and replacement or the availability of the grid, while the corresponding objective remains at least constant. Thus, a discrete optimization model is used to describe maintenance and replacement strategy mathematically. This model is solved with an adjusted approach of ant colony optimization. Finally, the benefits of this method are demonstrated for the optimized maintenance and replacement strategy at a 220 kV grid including 13 substations.