Research on Reliability Evaluation Method of Hydroelectric Unit Shaft System Based on TOPSIS

The working conditions of pumped-storage units change frequently, and it will gradually deviate from the normal operation state in the long-term operation process. The speed of unit performance degradation will gradually become faster over time, which will ultimately affect the safety of the unit operation. In this paper, the peak-to-peak value and rotating frequency amplitude of the upper guide swing of a pumped-storage unit are selected, and the technique for order preference by similarity to an ideal solution(TOPSIS) is used to evaluate the reliability of the shaft system of the pumped storage unit at the initial stage of operation, after long-term service, after A-level maintenance and after C-level maintenance. Through analysis, it is found that the reliability of the unit is more than 99% at the initial stage of operation. After 10 years of long-term operation, the reliability is reduced to less than 70%. Due to the loosening of the coupling bolts in the A-level maintenance, the reliability is only increased to more than 80%. After the C-level maintenance solves this problem, the reliability is increased to more than 90%. The calculation results can accurately reflect the reliability of each stage of the shaft system of the pumped storage unit, which has a good guiding significance for the operation and maintenance of the pumped storage unit.