Abstract: High voltage equipments are densely packed in the underground powerhouse of a pumped storage power plant (PSPP). characterized by its large, complex geometry and restricted ventilation, the powerhouse is prone to rapid smoke accumulation during a fire, threatening evacuation and equipment safety. Focusing on a typical PSPP’s generator floor and auxiliary building, this study develops a detailed fire dynamics model to simulate smoke spread from an electrical cabinet fire, with and without a mechanical smoke exhaust system. The evolution of smoke temperature, CO mole fraction, and visibility is analyzed quantitatively. Results show that without exhaust, smoke reaches the ceiling within seconds, with peak temperature and CO mole fraction at the source reaching 339 °C and 1 750×10-6; smoke penetrates lower passages within 200 s, severely reducing visibility. With the exhaust system activated, smoke-exhaust effect improve significantly: the peak temperature at the fire source is reduced by approximately 40.5%. In a fifth-floor auxiliary building fire scenario, visibility in walkways and lower stairwells improves by 28.5%~50%, and CO mole fraction decreases by about 20%~30%. This study demonstrates the smoke control effectiveness of mechanical exhaust in such complex environments, confirming its critical role in enhancing evacuation safety and mitigating risk, thereby providing technical support for optimizing fire protection design and emergency planning.

Key words: pumped storage power plant, underground powerhouse, numerical simulation, mechanical smoke exhaust, smoke dispersion