Determining Cost-Efficient Sequence of Condition Inspection Based on Estimated Condition Data

This paper presents a methodology to determine the cost-efficient sequence of substation equipment inspections. It is mainly intended for cases when having limited or absent data about equipment condition. The methodology is based on the usage of known condition data to estimate the condition of equipment with unknown data. It is estimated by fitting the likelihood function to the distribution of known Health Index values of equipment. The estimation values are implemented as an input to determine the cost-efficient sequence of equipment inspections. As a result, the process allows to decrease the uncertainty in condition data, avoid costly failures, and reduce total inspection cost. The methodology is tested on the IEEE 39-bus power system. The obtained results indicated the reduction of inspection cost by 80 % in the example case and avoiding failures with higher cost. The process can assist in risk reduction when having equipment with unknown or limited condition data.