Numerical Simulations of Hydraulic Transients in a Multisurge Tank Hydropower System

Abstract Hydraulic transients in hydroelectric power plants (HPPs), commonly induced by rapid load changes or emergency shutdowns, pose significant challenges to system safety and operational efficiency. Accurate simulation of transient flow behavior is particularly important in systems featuring complex surge tank configurations designed to mitigate pressure fluctuations. This study develops and applies a one-dimensional (1D) transient flow model that incorporates a flux-limited numerical scheme, aiming to ensure both computational efficiency and numerical stability. The model is validated using field data from the Zakučac HPP in Croatia, which includes a hydraulically complex layout with three throttled surge tanks, where two surge tanks are hydraulically interconnected via an overspill basin. Simulation results exhibited strong agreement with measured piezometric head data, particularly in capturing oscillation frequencies. Although some discrepancies in amplitude prediction were observed, the overall correspondence confirmed the model’s capability to represent transient flow dynamics accurately. The flux-limited approach effectively suppressed numerical dispersion and nonphysical oscillations, contributing to the reliability of simulations under severe transient conditions. The model’s performance demonstrates its applicability to HPP systems with nontrivial geometries and control elements, providing a practical tool for system analysis, design support, and operational planning. Findings from this study enhance current understanding of surge tank behavior during transients and support the use of simplified yet robust numerical schemes in the modeling of unsteady hydraulic phenomena in large-scale hydropower facilities.