Scheduling the Imperfect Maintenance and Replacement of Power Substation Equipment: A Risk-Based Optimization Model

A proper and effective maintenance and replacement schedule help to restore power equipment health condition, increase cost efficiency, and reduce the failure risk of the power grid. Imperfect maintenances cannot restore the equipment to a “as good as new” state as replacement did, but the financial cost of maintenance is much lower than that of replacement. The optimal balance and coordination between imperfect maintenances and replacements leads to the optimal substation operational cost. In this paper, a risk-based optimization model for power substation equipment maintenance and replacement scheduling is proposed in the presence of imperfect maintenances for the aging power equipment. The degradation process is firstly established based on historical trending analysis of failure data. Afterwards, a virtual age model is proposed for each equipment and the imperfect maintenance effectiveness is represented by the rejuvenation of this virtual age. Eventually, equipment failure risk, maintenance risk, and replacement risk are obtained, which are then incorporated into a MILP problem to obtain the optimal scheduling results. Case studies are performed on substations with three different bus-bar layout schemes. Results shows that the proposed method achieves a 34% lower total risk and 12.1% higher cost efficiency, compared to the traditional maintenance strategies.