Research on Multi-Objective Optimization to the Shape of Air Cushion Surge Tank

Abstract

Abstract This paper aims to research on multi-objective optimization to the shape of air cushion surge tank (ACST) in hydropower station. Firstly, a novel nonlinear mathematical model of hydropower station with ACST is established. Then, the analysis of the structure parameter of ACST on hydropower station during transient process is carried out. Furthermore, a multi-objective optimization and decision-making method is applied to determine the shape of ACST. Finally, it is carried out that the comparison analysis by numerical simulation between the optimal parameter and initial parameters of ACST under the checking condition. The results indicate that the impedance hole area, initial gas pressure and cross-sectional area has influence on the transient process index of hydropower station to a certain extent, so they are selected as optimization variables. The hydropower station shows superior dynamic quality under the optimized shape of ACST both in the design condition and in the checking condition. Specifically, the maximum water pressure at the end of volute is reduced by 5.84m and 5.19m respectively, the maximum pressure of air chamber decreases by 2.18m and 1.76m separately, and the extreme water level of ACST goes down by 3.82m and 3.81m solely under design condition and checking condition.