Grading early warning type fire extinguishing system for underground transformer substation

Abstract

The invention discloses a graded early warning type fire extinguishing system for an underground substation, which is characterized by comprising a central control terminal and a monitoring module, the monitoring module comprises a smoke sensor, the smoke sensor is in communication connection with the central control terminal, and the smoke sensor comprises a photoelectric smoke sensor and a failure emergency part which are fixedly connected. According to the invention, after the capturing unit captures a certain amount of smoke dust or dust, the lower part is broken along the fracture line relative to the upper part and the lower part falls down relative to the upper part under the self weight of the capturing unit, so that the photosensitive sensor and the alarm are separated from the inner cavity, and the photosensitive sensor gives an alarm after detecting a light beam. The failure emergency part can provide insurance, and when the photoelectric smoke sensor fails, smoke can be continuously monitored, so that the accuracy of smoke detection is improved, and the accuracy of the whole detection system is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of graded early warning fire fighting systems, and more specifically to a graded early warning fire fighting system for underground substations. Background Art

[0002] The main building of an underground substation is built underground, and the main transformer and other major electrical equipment are installed in the underground building. Only a small number of buildings such as substation ventilation holes and equipment, personnel entrances and exits, and cooling equipment and main control rooms for large main transformers that may be arranged on the ground are built on the ground. With the development of sensor technology and Internet of Things technology, the use of sensors to monitor substations located underground can greatly improve the safety of underground substations and reduce the possibility and hazards of fires.

[0003] A patent document with publication number CN 114821946 A discloses a fire warning method for an AC power supply in a substation. The scheme determines a first device with a hotspot based on an infrared image; determines a temperature change trend of the hotspot based on environmental parameters, electrical parameters of each first device and a first prediction model; determines a fire risk assessment value based on the temperature change trend and the type of each first device, and determines an expected fire level based on the type of power equipment; when the fire risk assessment value exceeds a preset threshold, an early warning is issued to an operation and maintenance terminal and the expected fire level is reported, the first device with a hotspot in each preset area is determined through an infrared image, and the change trend of the hotspot is predicted based on the electrical parameters and environmental parameters of the first device, thereby accurately assessing the fire risk and predicting the fire level, so as to provide an accurate early warning of the fire.

[0004] However, this early warning method is only applicable to above-ground substations, which have relatively open spaces and much higher heat dissipation efficiency than the narrow spaces of underground substations. Therefore, infrared imaging technology can be used to detect the temperature of each device to find the equipment with the greatest risk for early warning. However, due to the small space of underground substations, the equipment is relatively compactly stacked. Once the heat generated during operation cannot be dissipated in time, it is very easy to cause the overall temperature in the underground substation to rise, making it difficult to accurately locate high-risk equipment, which greatly reduces the reliability of the early warning system. Summary of the invention

[0005] The technical problem to be solved by the present invention is how to provide an accuracy of early warning for underground substations.

[0006] The present invention solves the above-mentioned technical problems through the following technical means: a hierarchical early warning fire protection system for an underground substation, characterized in that it includes a central control terminal and a monitoring module, the monitoring module includes a smoke sensor, the smoke sensor is communicatively connected to the central control terminal, the smoke sensor includes a fixedly connected photoelectric smoke sensor and a failure emergency part, the failure emergency part includes an upper part and a lower part, the end of the lower part facing away from the upper part is fixedly connected to the smoke sensor, the upper part is fixedly connected to the lower part, and a photosensitive sensor and an alarm are arranged in an inner cavity formed by them, the photosensitive sensor is electrically or communicatively connected to the alarm, the inner cavity is communicated with the photoelectric smoke sensor, and a capture unit is arranged in the inner cavity, the capture unit can drive the lower part to move relative to the upper part and cause the photosensitive sensor and the alarm to escape from the inner cavity.

[0007] As a preferred technical solution, the capture unit includes a plurality of elastic fibers, and the plurality of elastic fibers are stacked to form a three-dimensional space structure. The upper part and the lower part are provided with connection channels connected to the capture unit.

[0008] As a preferred technical solution, the failure emergency part includes an outer shell and an inner shell, the outer shell includes an upper shell and a lower shell, the upper shell forms the upper part, and the lower shell is fixedly connected to the inner shell and forms the lower part.

[0009] As a preferred technical solution, a negative pressure fan is provided at one end of the lower portion connected to the smoke sensor, and the negative pressure fan is in communication with the smoke sensor and the inner cavity.

[0010] As a preferred technical solution, the elastic fiber is a hollow spiral structure, and a surface groove is provided on the surface of the elastic fiber, and the surface groove is connected to the inner cavity of the elastic fiber.

[0011] As a preferred technical solution, the inner wall of the elastic fiber is coated with a capture coating.

[0012] As a preferred technical solution, the underground substation is provided with multiple monitoring areas, each of which is provided with at least one monitoring module. The monitoring module is also provided with a temperature sensor, a gas sensor and a video monitoring terminal. The temperature sensor, gas sensor and video monitoring terminal are communicatively connected to the central control terminal.

[0013] As a preferred technical solution, it also includes a fire-fighting unit, which is communicatively connected to the central control terminal and includes a fine water mist fire-extinguishing device and a full-flooding gas fire-extinguishing system.

[0014] As a preferred technical solution, the central control terminal is provided with a first-level alarm level, a second-level alarm level, and a third-level alarm level. The first-level alarm level, the second-level alarm level, and the third-level alarm level are all provided with corresponding temperature thresholds. When the first-level alarm temperature threshold is reached, the second-level alarm level is reached through manual processing, and the fine water mist fire extinguishing device in the alarm area is activated. When the third-level alarm level is reached, the total flooding gas fire extinguishing system is activated.

[0015] As a preferred technical solution, the preset threshold temperatures of the first alarm level, the second alarm level, and the third alarm level are T1, T2, and T3 respectively. When the temperature detected by the temperature sensor reaches T1, the central control terminal is preset to the first alarm, and the central control terminal calculates the temperature change efficiency:

[0016] S = (T1-T) / Δt;

[0017] Where S is the temperature change efficiency, Δt is the effective calculation time, T is the temperature of the underground substation when the current time is pushed forward by Δt, and Δt is evenly taken at intervals of 30 minutes for calculation. When the variance of multiple S values ​​is less than the first set value, the maintenance personnel manually increase the power of the heat dissipation equipment; when the temperature of the underground substation gradually stabilizes below T1, the first-level alarm is lifted, and when the variance of multiple S values ​​is between the first set value and the second set value, the safety level is raised to the second-level alarm, local emergency intervention is carried out, and the fine water mist fire extinguishing device in the alarm area is activated; when the variance of multiple S values ​​exceeds the second set value, the safety level is raised to the third-level alarm, and the full flooding gas fire extinguishing system is activated; when the temperature detected by the temperature sensor reaches T2, the central control terminal is set to the second-level alarm, and the temperature change efficiency S is calculated at the same time. When the variance of multiple S values ​​is between the first set value and the second set value, it means that there is a significant change in the temperature difference, and the safety level is raised to the third-level alarm; when the temperature detected by the temperature sensor reaches T3, the central control terminal is preset to the third-level alarm.

[0018] The beneficial effects of the present invention are:

[0019] (1) In the present invention, after the capture unit captures a certain amount of smoke or dust, its own weight causes the lower part to break relative to the upper part along the fracture line, and the lower part falls relative to the upper part, thereby causing the photosensitive sensor and the alarm to escape from the inner cavity. The photosensitive sensor detects the light beam and sounds an alarm. Compared with the traditional photoelectric smoke sensor, the existence of the failure emergency unit can provide an insurance. When the photoelectric smoke sensor fails, the smoke can continue to be monitored, thereby increasing the accuracy of smoke detection and thus improving the accuracy of the entire detection system.

[0020] (2) In the present invention, multiple safety levels are set through the central control terminal, and multiple detection modules detect the parameters of the underground substation. According to the detection results, graded warnings are issued, which greatly increases the accuracy of the warning system. In the temperature detection process, three threshold temperatures are set corresponding to three warning levels, and the temperature change range of the underground substation is detected. Each warning level is upgraded to increase the accuracy of the warning system, so that dangerous situations can be discovered in time and the expansion of dangerous situations can be effectively avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic diagram of the overall structure provided by an embodiment of the present invention;

[0022] Figure 2 A schematic diagram of the structure of a fire fighting unit provided in an embodiment of the present invention;

[0023] Figure 3 A schematic diagram of security levels provided by an embodiment of the present invention;

[0024] Figure 4 A schematic diagram of the structure of a photoelectric smoke sensor provided by an embodiment of the present invention;

[0025] Figure 5 A schematic diagram of the cross-sectional structure of a failure emergency unit provided by an embodiment of the present invention;

[0026] Figure 6 A schematic diagram of a partially enlarged structure provided by an embodiment of the present invention;

[0027] Figure 7 Another partial enlarged structural schematic diagram provided by an embodiment of the present invention;

[0028] Figure 8 A schematic diagram of a shell fracture structure provided by an embodiment of the present invention;

[0029] Fig. 9 A schematic diagram of the elastic fiber structure provided by an embodiment of the present invention;

[0030] Fig.10 The embodiment of the present invention provides Fig. 9 A schematic diagram of a local enlarged structure;

[0031] Figure numbers: 1. Photoelectric smoke sensor; 2. Failure emergency unit; 201. Outer shell; 2011. Upper shell; 2012. Lower shell; 202. Through hole one; 203. Inner shell; 204. Through hole two; 205. Connecting rope; 206. Fixed bracket; 207. Shading cover; 3. Photosensor; 4. Alarm; 5. Capture unit; 501. Elastic fiber; 502. Surface groove; 503. Capture coating; 6. Negative pressure fan. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] See also Figure 1 , Figure 2 A hierarchical early warning fire fighting system for an underground substation includes a central control terminal, a data processing terminal, a fire fighting unit, a maintenance terminal, and a monitoring module. The data processing terminal, the fire fighting unit, the maintenance terminal, and the monitoring module are all communicatively connected to the central control terminal. The fire fighting unit includes a fine water mist fire extinguishing device and a full flooding gas fire extinguishing system. The fine water mist fire extinguishing device and the full flooding gas fire extinguishing system are both prior arts and are arranged in the underground substation. The detection module includes a temperature sensor, a gas sensor, a smoke sensor, and a video monitoring terminal. The maintenance terminal is communicatively connected to the video monitoring terminal.

[0034] See also Figure 3 The central control terminal is equipped with multiple security levels, specifically, there are three security levels from low to high, namely, level one alarm, level two alarm and level three alarm. In the level one alarm stage, manual intervention is required. In the level two alarm stage, local emergency response is carried out in the alarm area, and the fine water mist fire extinguishing device in the alarm area is activated. In the level three alarm stage, comprehensive emergency response is carried out in the entire area of ​​the underground substation, and the full flooding gas fire extinguishing system is activated.

[0035] It should be noted that according to the structural layout and equipment distribution of the underground substation, the underground substation is divided into one or more monitoring areas, and the above-mentioned detection modules are arranged in each area, and multiple monitoring modules can be arranged in the same area. The monitoring modules can monitor the temperature, gas concentration, smoke concentration and other parameters of each area in real time, and transmit the data to the central control terminal. The data processing terminal is used to process the above data, and the data is cleaned, denoised and normalized to remove redundant and obviously erroneous data, and determine whether there is a fire risk in each detection area. The connection method between each electrical terminal and the module is a well-known technology for those skilled in the art, so the corresponding installation, connection and data communication methods are not disclosed in detail in this application.

[0036] Taking temperature detection as an example, the preset threshold temperatures T1, T2, and T3 corresponding to three safety levels are pre-entered in the central control terminal. When the temperature detected by the temperature sensor reaches T1, the central control terminal is preset as a first-level alarm. At the same time, the central control terminal processes the temperature data and calculates the temperature change efficiency: in this embodiment, the first setting value is 2, and the second setting value is 30;

[0037] S = (T1-T) / Δt;

[0038] Where S is the temperature change efficiency, Δt is the effective calculation time, and T is the temperature of the underground substation when the current time is pushed forward by Δt. Δt is calculated by taking 5-10 data at uniform intervals within a 30-minute interval. When the variance of multiple S values ​​is less than 2, it means that the temperature is accumulating at a uniform speed. The maintenance personnel manually increase the power of the heat dissipation equipment. When the temperature of the underground substation gradually stabilizes below T1, the first-level alarm is lifted. When the variance of multiple S values ​​is between 2-30, it means that there is a significant change in the temperature difference. The safety level is increased to the first-level value and the second-level alarm. Local emergency intervention is carried out and the fine water mist fire extinguishing device in the alarm area is activated. When the variance of multiple S values ​​exceeds 30, it means that there is a sharp change in the temperature difference. The safety level is increased from the second to the third level alarm, and comprehensive emergency intervention is carried out. Comprehensive emergency response is carried out for the entire area of ​​the underground substation, and the full flooding gas fire extinguishing system is activated. The critical values ​​of variance 2 and 30 can be set according to actual conditions.

[0039] When the temperature detected by the temperature sensor reaches T2, the central control terminal is preset to a level 2 alarm, local emergency intervention is initiated, and the temperature change efficiency S is also calculated. When the variance of multiple S values ​​is between 2-30, it indicates that there is a significant change in the temperature difference, and the safety level is raised from level 1 to level 3 alarm, with full emergency intervention;

[0040] When the temperature detected by the temperature sensor reaches T3, the central control terminal is preset to level 3 alarm and comprehensive emergency intervention.

[0041] Compared with the substation on the ground, the underground substation has a relatively closed space. Under the premise that the heat dissipation system works normally, the underground substation can sensitively detect abnormal heat accumulation. Therefore, this embodiment is mainly aimed at the early stage of the fire, when no open flame is generated. At this time, the change in heat accumulation is used to achieve early warning of the fire.

[0042] Therefore, this embodiment uses the area where cables are stored in the underground substation. The heat generated in these areas comes from the accumulation of the cable's own work, and the heat generation is obviously progressive. The hierarchical warning system in this embodiment can detect the early stage of the fire in time and deal with it in sufficient time. The hierarchical warning effect is the best;

[0043] However, there are areas in underground substations where fires develop rapidly, such as transformer areas. In these areas, fires will develop rapidly in the early stages of fire development. At this time, the temperature change detection effect used in this application is relatively poor, so it is also possible to combine the infrared detection and image detection in the prior art for joint early warning. At the same time, the transformer oil loaded in the transformer will decompose into gases of different concentrations at different temperatures, producing methane, ethane, propane and other gases at low temperatures. As the temperature rises further, the transformer oil will decompose into unsaturated hydrocarbons: ethylene and propylene, etc., and at extremely high temperatures, the transformer oil is almost completely decomposed into hydrogen, methane and acetylene. Therefore, in the storage substation area, the above-mentioned gas concentrations can be detected to achieve the detection of the transformer operating temperature. At the same time, the temperature change efficiency S value in the graded early warning system can also be appropriately adjusted, thereby changing the detection agility of the graded early warning system, increasing the sensitivity of the early warning of fire, and providing more reaction time for maintenance personnel.

[0044] In addition, areas where fires develop faster must be separated at the initial design stage of the underground substation, and corresponding partition equipment must be installed in the corresponding areas. Once a fire occurs, the areas where the fire develops faster must be isolated in time to avoid rapid development of the fire, which is less likely to induce chain explosions and reduce the hazards of underground substation fires.

[0045] The startup of the fire-fighting unit involves both automatic operation and manual control. In the above process, when the underground substation reaches the first-level alarm, the maintenance personnel have already started the manual early warning. Therefore, when the second-level alarm and the third-level alarm occur, the maintenance personnel can manually handle the emergency intervention of the above alarms according to the actual detection situation, avoiding the risks brought by data errors caused by the failure of the temperature sensor, and also avoiding the failure of the automatic startup of the fire-fighting unit.

[0046] See also Figure 4 , Figure 5The smoke sensor in this embodiment is fixed on the top of the underground building, and includes a photoelectric smoke sensor 1 and a failure emergency unit 2 that are fixedly connected, wherein the failure emergency unit 2 is fixed on the top of the underground building, and the photoelectric smoke sensor 1 is fixed to the end of the failure emergency unit 2 that is away from the top of the underground building. The failure emergency unit includes an outer shell 201 and an inner shell 203. The outer shell 201 is a hollow columnar structure, which includes a separable upper shell 2011 and a lower shell 2012. The upper shell 2011 is an upper structure, and the inner shell 203 is fixedly connected to the inner wall of the outer shell 201, and its axis is coaxial with the outer shell 201. The inner shell 203 is fixedly connected to the lower shell 2012, and the inner shell 203 and the lower shell 2012 form a lower structure. The outer shell 201 is provided with a plurality of through holes 202 distributed at equal angles in the circumferential direction, and the inner shell 203 is provided with a through hole 204 connected with the through hole 202, so that the through hole 202 can be connected with the annular cavity provided in the inner shell 203 through the through hole 204, and a photosensitive sensor 3 is fixedly connected to one end of the outer shell 201 facing the inner shell 203, and an alarm 4 is fixedly connected to the bottom of the photosensitive sensor 3, and a light shielding sleeve 207 is provided at the center of the inner shell 203, and the light shielding sleeve 207 is fixedly connected to the inner shell 203 through a plurality of fixed brackets 206 in the circumferential direction, and gaps are left between the plurality of fixed brackets 206, and a central channel is provided at the center of the inner shell 203 to ensure that the central channel is connected with the annular cavity through the gap;

[0047] See also Figure 5 , Figure 6 , Figure 7 The shape of the light shielding sleeve 207 is adapted to the photosensitive sensor 3 and the alarm 4, so as to shield the photosensitive sensor 3 and the alarm 4. The photosensitive sensor 3 is electrically or communicatively connected to the alarm 4. A negative pressure fan 6 is provided at the bottom of the inner shell 203. The negative pressure fan 6 can suck the air and smoke near the photoelectric smoke sensor 1 into the photoelectric smoke sensor 1 and the central channel. During the normal operation of the photoelectric smoke sensor 1, it can timely detect the excessive smoke in the underground substation and sound an alarm.

[0048] There is a detection chamber in the photoelectric smoke sensor 1. When smoke enters the detection chamber, it will cause the light generated by the light source in the photoelectric smoke sensor 1 to be refracted and refracted onto the photosensor 3, and an alarm will be issued. This is the structure of the existing photoelectric smoke sensor 1, so it is not disclosed in detail in this application, and the area where the negative pressure fan 6 is located is connected to the detection chamber.

[0049] See also Figure 5 , Figure 8, the through hole 1 202 is partially located on the upper shell 2011, and partially located on the lower shell 2012. In this embodiment, the middle of the shell 201 is the dividing line between the upper shell 2011 and the lower shell 2012, and a fracture line is provided at the connecting end of the upper shell 2011 and the lower shell 2012. A capture unit 5 capable of capturing smoke is provided in the annular cavity. When the photoelectric smoke sensor 1 fails, the smoke in the underground substation will also be sucked into the failure emergency part 2, that is, enter the annular cavity through the central hole, and be captured by the capture unit 5. When the capture unit After the element 5 captures a certain amount of smoke or dust, its own weight causes the lower shell 2012 to break from the upper shell 2011 along the fracture line, and the lower shell 2012 drives the inner shell 203 to fall relative to the upper shell 2011, so that the photosensitive sensor 3 and the alarm 4 are separated from the light shielding cover 207. The photosensitive sensor 3 sounds an alarm after detecting the light beam. Compared with the traditional photoelectric smoke sensor 1, the existence of the failure emergency unit 2 can provide an insurance. When the photoelectric smoke sensor 1 fails, it can continue to monitor the smoke, thereby increasing the accuracy of smoke detection.

[0050] It should be noted that the total amount of smoke required for the outer shell 201 to break can be controlled by controlling the size of the through hole 202, thereby changing the sensitivity of the failure emergency unit 2. At the same time, with the daily use of the failure emergency unit 2, smoke will normally accumulate on its inner wall. Therefore, even if no fire occurs, the outer shell 201 may break. At this time, the photoelectric smoke sensor 1 is still in normal working condition. The staff can judge the specific situation according to the actual situation and replace the aged photoelectric smoke sensor 1 and the failure emergency unit 2 in time.

[0051] See also Figure 4 In order to prevent the lower shell 2012 from falling off from the top of the underground building after being separated from the upper shell 2011, the upper shell 2011 is fixedly connected to the lower shell 2012 by a connecting rope 205, one end of the connecting rope 205 is fixedly connected to the top inner wall of the through hole 202 on the upper shell 2011, and the other end is fixedly connected to the bottom inner wall of the through hole 202 on the lower shell 2012.

[0052] See also Fig. 9 , Fig.10 The capture unit 5 includes a plurality of elastic fibers 501, which can overlap and stack with each other to form a three-dimensional structure. The elastic fiber 501 is a hollow spiral structure, and a surface groove 502 is provided on its surface. The surface groove 502 is connected with the inner wall of the elastic fiber 501, thereby increasing the dust capture effect. The inner wall of the elastic fiber 501 is coated with a capture coating 503. The capture coating 503 is a sticky coating for fixing dust, which is not easy to cause smoke leakage and be sucked in again by the failed emergency unit 2, thereby reducing the impact on the detection accuracy.

[0053] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A hierarchical early warning fire protection system for underground substations, characterized in that: It includes a central control terminal and a monitoring module. The monitoring module includes a smoke sensor. The smoke sensor is communicatively connected to the central control terminal. The smoke sensor includes a fixedly connected photoelectric smoke sensor and a failure emergency part. The failure emergency part includes an upper part and a lower part. The end of the lower part facing away from the upper part is fixedly connected to the smoke sensor. The upper part and the lower part are fixedly connected. A photosensitive sensor and an alarm are arranged in an inner cavity formed by them. The photosensitive sensor is electrically or communicatively connected to the alarm. The inner cavity is communicated with the photoelectric smoke sensor. A capture unit is arranged in the inner cavity. The capture unit can drive the lower part to move relative to the upper part and cause the photosensitive sensor and the alarm to escape from the inner cavity.

2. A hierarchical early warning fire protection system for underground substations according to claim 1, characterized in that: The capture unit includes a plurality of elastic fibers, and the plurality of elastic fibers are stacked to form a three-dimensional space structure. The upper part and the lower part are provided with connection channels communicating with the capture unit.

3. A hierarchical early warning fire protection system for underground substations according to claim 2, characterized in that: The failure emergency part includes an outer shell and an inner shell, the outer shell includes an upper shell and a lower shell, the upper shell forms the upper part, and the lower shell is fixedly connected to the inner shell and forms the lower part.

4. A hierarchical early warning fire protection system for underground substations according to claim 1, characterized in that: A negative pressure fan is arranged at one end of the lower part connected to the smoke sensor, and the negative pressure fan is communicated with the smoke sensor and the inner cavity.

5. A hierarchical early warning fire fighting system for underground substation according to claim 2, characterized in that: The elastic fiber is a hollow spiral structure, and a surface groove is provided on the surface of the elastic fiber, and the surface groove is communicated with the inner cavity of the elastic fiber.

6. A hierarchical early warning fire fighting system for underground substation according to claim 5, characterized in that: The inner wall of the elastic fiber is coated with a capture coating.

7. A hierarchical early warning fire fighting system for underground substation according to claim 1, characterized in that: The underground substation is provided with a plurality of monitoring areas, each of which is provided with at least one monitoring module. The monitoring module is also provided with a temperature sensor, a gas sensor and a video monitoring terminal. The temperature sensor, the gas sensor and the video monitoring terminal are communicatively connected with the central control terminal.

8. A hierarchical early warning fire fighting system for underground substation according to claim 7, characterized in that: It also includes a fire-fighting unit, which is communicatively connected to the central control terminal and includes a fine water mist fire-extinguishing device and a full-flooding gas fire-extinguishing system.

9. A hierarchical early warning fire fighting system for underground substations according to claim 8, characterized in that: The central control terminal is provided with a first-level alarm level, a second-level alarm level, and a third-level alarm level. The first-level alarm level, the second-level alarm level, and the third-level alarm level are all provided with corresponding temperature thresholds. When the first-level alarm temperature threshold is reached, the second-level alarm level is reached through manual processing, and the fine water mist fire extinguishing device in the alarm area is activated. When the third-level alarm level is reached, the total flooding gas fire extinguishing system is activated.

10. A hierarchical early warning fire fighting system for underground substation according to claim 9, characterized in that: The preset threshold temperatures of the first-level alarm level, the second-level alarm level, and the third-level alarm level are T1, T2, and T3 respectively. When the temperature detected by the temperature sensor reaches T1, the central control terminal presets the first-level alarm, and at the same time, the central control terminal calculates the temperature change efficiency: S = (T1-T) / Δt; Where S is the temperature change efficiency, Δt is the effective calculation time, T is the temperature of the underground substation when the current time is pushed forward by Δt, and Δt is evenly taken at intervals of 30 minutes for calculation. When the variance of multiple S values ​​is less than the first set value, the maintenance personnel manually increase the power of the heat dissipation equipment; when the temperature of the underground substation gradually stabilizes below T1, the first-level alarm is lifted. When the variance of multiple S values ​​is between the first set value and the second set value, the safety level is raised to the second-level alarm, local emergency intervention is carried out, and the fine water mist fire extinguishing device in the alarm area is activated; when the variance of multiple S values ​​exceeds the second set value, the safety level is raised to the third-level alarm, and the full flooding gas fire extinguishing system is activated; when the temperature detected by the temperature sensor reaches T2, the central control terminal is set to the second-level alarm, and the temperature change efficiency S is calculated at the same time. When the variance of multiple S values ​​is between the first set value and the second set value, it means that there is a significant change in the temperature difference, and the safety level is raised to the third-level alarm; When the temperature detected by the temperature sensor reaches T3, the central control terminal is preset to a level 3 alarm.

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