Abstract: In order to systematically evaluate the efficiency of the fixed firefighting system in the fire and explosion scene of underground substation, the efficiency architecture of the fixed firefighting system in underground substation is proposed based on safety system engineering, numerical simulation and test. Taking the main transformer room of a 500 kV underground substation as the research object, the qualitative analysis of system reliability and the evaluation of system survivability under fire and explosion conditions were carried out. The results show that under the simulation conditions of top oil tank tear fire and oil collecting pool fire, the flame baking at high temperature for a long time was very likely to ignite the transformer in the fuel tie and cause the accident chain effect. When the precipitated oil vapor cloud develops fully around the transformer and ignites, the maximum overpressure at the fire pipe and wall corresponding to the central ignition was about 54.0 kPa, and the maximum overpressure value under the condition of one side ignition is 73.9 kPa. Due to the impact of flame and high temperature, the sprinkler of non-stainless steel was likely to melt and the fire pipe was deformed. Therefore, it is necessary to take corresponding measures to improve the dry burning and explosion resistance of the fire pipe system in underground substations.

Key words: underground substation, fixed firefighting systems, fire, explosion