Critical stable sectional area of downstream surge tank of hydropower plant with sloping ceiling tailrace tunnel

Abstract

This paper investigates the critical stable sectional area (CSSA) of downstream surge tank (DST) of hydropower plant with sloping ceiling tailrace tunnel (SCTT). Firstly, two types of nonlinear mathematical model of hydropower plant with SCTT during transient process are established. Then, the criterion of operation stability of hydropower plant is obtained based on nonlinear stability theory. Formulae for CSSAs of DST under two types of mathematical model are derived. Finally, the similarities, differences, and relationships of different CSSAs are clarified. The effect mechanisms of the assumption of steady power output of hydro‐turbine and the SCTT on CSSA of DST are revealed. The recommended use conditions of different CSSAs are explained. The results indicate that, under the assumption of steady power output of hydro‐turbine, the formula for CSSA of DST of hydropower plant with SCTT is analytical and has a simple expression. Under the complete model, the formula for CSSA of DST of hydropower plant with SCTT is not analytical and has a complicated expression. The former formula is suggested to be given the priority of use because of good precision and concise expression. SCTT can improve the stability of hydropower plant and decrease the CSSA of DST.

Optimization of hydraulic parameters for pipeline system of hydropower station with super long headrace tunnel based on mayfly algorithm considering operational scenarios

“…For the HSSLHT, the flow inertia of SLHT is great, and the nonlinearity of head loss of SLHT is strong. Moreover, a huge surge tank is necessary to weaken the water hammer phenomenon 9–12 . The great flow inertia of SLHT and huge surge tank increase the difficulty of optimization of hydraulic parameters.…”

“…Moreover, a huge surge tank is necessary to weaken the water hammer phenomenon. [9][10][11][12] The great flow inertia of SLHT and huge surge tank increase the difficulty of optimization of hydraulic parameters. The coupling effect between pipelines and surge tank leads to the interaction of different hydraulic parameters.…”

Time‐ and frequency‐domain analyses of the hydraulic system using a discrete numerical scheme based on equivalent circuit modelling

“…However, these models have too many tunable parameters due to their structural complexity, so parameter identification is challenging. Besides this, the strict tempo-spatial restrictions resulting from the well-known Courant-Friederichs-Lewy (CFL) stability criteria 14,15 prohibit the coordination of the time step of the discrete-time simulation and the spatial steps of different pipes, especially for hydraulic systems with complex network structure.…”