Structural optimization of ultra-high-head pumped-storage units for ensuring the safety of the new-type power system

The worldwide low-carbon transformation keeps progressing, and building a new power system centered on renewable energy is key to low-carbon development. However, wind and solar energy exhibit intermittent and random characteristics, with output heavily influenced by natural conditions. This can easily lead to fluctuations in power generation and voltage instability within the power system, challenging supply-demand balance while also threatening the safe and stable operation of the system. Frequent switching between pumping and generating modes in ultra-high-head pumped-storage units can trigger severe fluctuations in internal flow velocity and pressure. Excessively high pressures may damage structural components, compromising safe operation. This study systematically investigates the structural behavior of the head-cover, stay-ring and bottom ring assembly under maximum pressure conditions. A three-dimensional model of the assembly was established and discretized with a tetrahedral mesh for numerical simulation. Maximum pressure loads were applied to the component surfaces, and the resulting stress distributions and deformation patterns were analyzed. Based on these results, targeted structural optimization was conducted to improve stability and reliability. The findings provide guidance for the design and optimization of the head-cover and stay-ring assembly, supporting the safe and stable operation of ultra-high-head pumped-storage units under the maximum conditions, while also providing critical assurance for the stable operation of the core new-type power system.