Fire Spread Law Of High-voltage Cable Channels In Substations And Improvement Methods Of Fire Blocking

The high-voltage cable channel of the substation is an important part of ensuring the safe operation of the power system,and its fire and disaster resistance capabilities are very important.However,there have been few scientific researches on fire protection of high-voltage cable trenches in substations,and the research on fire disaster mechanism and protection of substations was rarely reported.In particular,the influence of factors such as the gap of the firewall inside the high-voltage cable trench of the substation and the fire-proof sealing material on the spread of fire was less studied.Therefore,this paper conducted a deeper study on the fire spread law of high-voltage cable trenches in substations and the gaps in firewalls,and established a simulation model of power cable fires in high-voltage cable trenches in substations.This paper carried out simulation experiments on the existence of gaps in the firewall,as well as the size,number and location of gaps in the firewall.Focus on the analysis of smoke diffusion,temperature field changes and toxic gas concentration changes to explore the impact of fire spreading under different conditions of the firewall gaps.This paper proposed three improvement measures,which were verified by simulation tests,which proved the effectiveness of the improvement measures in this paper.The main findings were as follows:1.Explored the theoretical basis of combustion and constructed a fire simulation model for high-voltage cable trenches.Analyzed the smoke propagation process,the change of temperature field and the trend of toxic gas diffusion when the firewall gap exists.2.In terms of the size of the gap,the larger the gap,the shorter the time for the smoke to diffuse to the B zone,and the ceiling temperature of the B zone would increase accordingly.The volume fraction of toxic gases would increase as the size increases.In terms of the position of the gap,the closer the gap to the top of the cable trench,the faster and more heat transfer,and the faster the ceiling temperature of the B zone would rise.When the gaps were on the same plane,the gaps on the side of the fire source got more heat,and the temperature value of zone B was also higher.In terms of the number of gaps,as the number of gaps increases,the diffusion rate of smoke increases.For the ceiling temperature,every time a gap was added,the temperature value increased by one level.The concentration of toxic gas increased with the increase of the gap.Regarding the wind speed of the vent,as the wind speed increased,the temperature shows obvious stratification.3.After adding the fire-resistance package and heat insulation board,the spread of smoke,heat and toxic gases were suppressed,which obviously delayed the spread of fire,and reduced the burning rate and the concentration in the high-voltage cable channel.In terms of laying cable trays,when the full-wrapped laying method was adopted,the toxic gas generated in Zone A was late and had a low concentration.In terms of the spread of smoke,the way of laying had little effect on the spread of smoke.In terms of heat transmission,the laying method had no effect on the rise time for the A zone to reach the highest temperature.For zone B,it took longer to reach the highest temperature using the full laying method than the other two laying methods,and the temperature value was smaller.The relevant research results of this article can provide a lot of help and reference value for the fire protection measures of high-voltage cable trench power cables in substations.It can effectively improve the fire resistance of cables in the high-voltage cable channel of the substation,and provide scientific guidance for the safe,stable and reliable operation of the high-voltage cable channel of the substation.