OPTIMIZATION OF A STEEL PENSTOCK WITH STIFFENER RINGS

Abstract

The paper presents the optimization of a high-pressure steel penstock with stiffener rings, which is constructed in a bored tunnel for a pump storage hydroelectric plant. The optimization is performed using nonlinear programming (NLP) methods, and an NLP optimization model is developed. The mass of the steel structure is defined in the objective function to be minimized and structural (in) equality constraints are imposed. The latter comprise the dimensioning equations of a steel penstock, which is exposed to the internal and external water pressure cases. Only the main constraints are introduced in the paper. They include checking the circumferential stresses in the pipe owing to internal water pressure, as well as the critical pressures in the steel liner and stiffener rings when the pipe is exposed to the external water pressure. The numerical example at the end of the paper describes the optimization of the high-pressure steel penstock for the pumped hydropower plant Kozjak, which will be constructed in Slovenia near the city of Maribor.