Analysis of Distribution Law of Fire Gas Concentration in Underground Cable Tunnel of Substation

摘要

With the continuous innovation of power grid construction, the scale of cable tunnel is expanding. However, the safety of the cable tunnel, especially the substation cable tunnel, has also become a problem that cannot be ignored. Once a fire occurs in the cable tunnel, it will affect the normal operation of the power grid and even cause huge economic loss. By analyzing the distribution law of gas concentration during the fire in the cable tunnel, timely and effective fire-extinguishing method can be adopted to effectively reduce the fire loss. Based on the fire simulation software, a simulation model was established for the 35kV outgoing cable tunnel of the simulated substation in this paper. The heat source power was set at 8000kW/m^{2. The cable length was set to 16.6m, the cable spacing was 0.04m, and the simulation time was 600s. Fire simulation was carried out on the cable tunnel model with “one” type and “triangle” type cable layout, and the gas content and diffusion caused by the cable combustion in A and B areas were analyzed. The following conclusions were drawn: the cable layout had no obvious influence on the gas diffusion in the cable tunnel fire; Compared with “one” type cable arrangement, “triangle” type arrangement increased the output of carbon monoxide and decreased the output of carbon dioxide produced by combustion. The arrangement of cables had no obvious effect on the gas diffusion and concentration distribution in the tunnel fire. The gas concentration stratification phenomenon existed in zone A of the two types of cable combustion. The carbon monoxide content in the product of cable combustion could be reduced by using “one” type cable arrangement, which was of great significance to the safety of the workers in cable tunnel fire extinguishing.}