Equipotential connection method for electrical equipment of integrated grounding system of section track-free circuit

Abstract

The invention relates to the technical field of railway comprehensive grounding, in particular to an equipotential connection method for electrical equipment of a comprehensive grounding system of an interval trackless circuit. The method comprises the following steps that in railway bridge and tunnel sections, a steel rail replaces a through ground wire to serve as a common ground wire, a grounding device is electrically connected with the steel rail in a single-point mode according to a preset distance, and electrical equipment is electrically connected with the grounding device. The invention provides an equipotential connection method for an electrical equipment facility and an integrated grounding system in order to meet the requirements of integrated grounding specifications under the condition that a track-free circuit is arranged in an interval and a through ground wire is replaced by a steel rail. The problems that interference is generated due to uneven ground potential between electrical equipment facilities in the same system and dangerous contact voltage exists on the electrical equipment facilities are solved.

Description

Technical Field

[0001] The invention relates to the technical field of integrated grounding, in particular to an equipotential connection method for electrical equipment of an integrated grounding system of an interval without track circuit. Background Art

[0002] The current standard of the high-speed railway integrated grounding system is developed based on the section-based ZPW-2000 track circuit. By setting up a separate through-ground wire as a common ground wire, the equipotential connection between the electrical equipment and facilities along the railway and the integrated grounding system is achieved. The through-ground wire is the core carrier of the integrated grounding system. The rails, return lines, through-ground wires and the earth constitute the return channel for the traction return current, of which the through-ground wire bears 15-20% of the traction return current. In the existing specifications, the integrated grounding system solves the electromagnetic interference between the ZPW-2000 track circuit equipment and the traction return current by setting up a separate through-ground wire, so as to achieve compatibility between the signal track circuit and the traction return current system.

[0003] High-speed railways in dangerous mountainous areas have many equipment points and long lines, and face difficulties in construction and operation and maintenance. There are no track circuits in the sections. In addition, the construction goals of the new CTCS-4 level train control system and the CBTC railway under the AC traction power supply system also have the characteristics of no track circuits in the sections. If there is no ZPW-2000 track circuit equipment in the section, the best existing return conductor, the steel rail, can be used to replace the through-ground wire as a common ground wire. The advantage of this solution is that there is no need to lay a through-ground wire separately along the railway line, which can significantly improve the efficiency of construction and operation and maintenance, reduce maintenance difficulties and other problems, and adapt to the harsh natural geographical environment and high-speed railways in harsh operating environments to the greatest extent. Rails are the main channel for traction return current. After rails replace through-ground wires as the common ground wires of the integrated grounding system, they bear their own original return current and 15-20% of the return current of the through-ground wires. At the same time, the high-speed railways in dangerous mountainous areas have long and continuous slopes, and the traction return current of the EMUs increases. Therefore, the return amplitude of rails, return wires, through-ground wires and the earth will be redistributed. The return on the through-ground wire may be much larger than the existing amplitude, and its cross-sectional area will also change significantly accordingly, bringing many challenges to the existing design, construction and construction quality acceptance standards. Using rails instead of through-ground wires as common ground wires can completely solve this problem, that is, there is no need to re-study the technical requirements of through-ground wires and related supporting components.

[0004] Since the return amplitude on the rail is much larger than the return amplitude under the through-ground wire scheme in the prior art, it is also necessary to overcome a series of problems caused by the steel rail replacing the through-ground wire as the common ground wire. For example, electrical equipment and facilities are directly connected to the steel rail as the common ground wire, or the electrical equipment and facilities of urban rail transit are connected to the corresponding grounding flat steel according to the strong and weak electricity, which will lead to uneven grounding potentials between equipment in the same system, thereby causing interference between electrical equipment and facilities, as well as the problem of dangerous contact voltage on electrical equipment and facilities. The electromagnetic interference problem and the dangerous contact voltage problem are very obvious in the electronic information equipment in the railway AC power supply system. The electronic information equipment that is easily affected includes axle counting equipment, communication optical cables, and electronic information equipment in buildings such as signal towers and repeaters. Summary of the invention

[0005] In order to solve the problem of interference to facilities and equipment caused by uneven potential after replacing the through-ground wire with steel rails and the problem of dangerous contact voltage on electrical equipment and facilities, the present invention proposes an equipotential connection method for electrical equipment in an integrated grounding system with no track circuits in sections.

[0006] In order to achieve the above objectives, the following technical solutions are proposed: The equipotential connection method of electrical equipment in the integrated grounding system of the section without track circuit includes the following steps: In the bridge and tunnel sections of the railway, steel rails are used instead of through ground wires as common ground wires. The grounding device is electrically connected to the steel rails at a single point at a preset distance, and the electrical equipment is electrically connected to the grounding device.

[0007] Furthermore, the grounding device includes a grounding wire, a grounding terminal and a grounding body. The grounding body is connected to the grounding wire and the grounding terminal respectively. The grounding wire is used to connect to the rails, and the grounding terminal is used to connect to electrical equipment and facilities.

[0008] Furthermore, two grounding terminals are added on both sides of the line of each span of the bridge, and two grounding terminals are added to the protective walls on both sides of the line every 100m in the tunnel, and the grounding terminals at the bottom of the communication signal cable troughs of the bridge and tunnel are cancelled.

[0009] Furthermore, the equipotential connection between the bridge and tunnel grounding devices and the rails adopts the nail type, and the connecting wire is galvanized steel stranded wire.

[0010] Furthermore, in ballasted track sections, special capacitor pillows are used to place the equipotential connecting wire in the protective groove, and in ballastless track sections, clamps and chemical anchors are used to directly fix them on the ballastless track slab.

[0011] Furthermore, the grounding wire uses two stainless steel connecting wires of equal resistance, one long and one short.

[0012] Furthermore, the grounding body includes an artificial grounding body and a natural grounding body, and the natural grounding body includes steel bars in civil reinforced concrete.

[0013] Furthermore, the steel bars in the civil engineering reinforced concrete include structural steel bars in the civil engineering structures of bridges and tunnels.

[0014] Furthermore, the preset distance is 150m.

[0015] Furthermore, the electrical equipment includes axle counting equipment, communication optical cables, electronic information equipment in communication signal towers, and electronic information equipment in repeater station buildings.

[0016] Compared with the prior art, the method of the present invention has the following beneficial effects: under the premise of using steel rails instead of through-ground wires to realize traction return, the method of the present invention provides a method for connecting electrical facilities and equipment to the steel rails and the grounding device at the same potential, respectively, thereby avoiding the interference caused by uneven ground potential between electrical equipment and facilities in the same system and the problem of dangerous contact voltage on the electrical equipment and facilities, and also solving the problem of a re-study of the parameter performance of through-ground wires and corresponding supporting parts when the traction return increases sharply on long slopes in dangerous mountainous areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic diagram of the equipotential connection between the electrical equipment and the rail in the prior art in Example 1; Figure 2 It is a schematic diagram of the electrical equipment facilities of the prior art in Example 1 being connected to the corresponding grounding flat steel with equal potential according to the strong and weak electricity; Figure 3 It is a schematic diagram of an equipotential connection method for electrical equipment in a comprehensive grounding system without track circuits in a section in Example 1; FIG4 (a) is a schematic diagram of the grounding terminal setting on the short mileage side of the bridge section in Example 1 before the change; FIG4( b ) is a schematic diagram of the grounding terminal setting change on the small mileage side of the bridge section in Example 1; FIG5 (a) is a schematic diagram of the grounding terminal setting on the long mileage side of the bridge section in Example 1 before the change; FIG5( b ) is a schematic diagram of the grounding terminal setting change on the long mileage side of the bridge section in Example 1; Figure 6 is a schematic cross-sectional view of the connection between the bridge grounding device and the rail in Example 1; FIG7 (a) is a schematic diagram of the tunnel section grounding terminal before installation in Example 1; FIG7( b ) is a schematic diagram of the grounding terminal after being set in the tunnel section in Example 1; Figure 8It is a comprehensive grounding stereoscopic system diagram in which the grounding device in the tunnel in Example 1 is connected to the rail at a single point at 150m; Fig. 9 is a schematic cross-sectional view of the connection between the grounding device and the rail in the tunnel in Example 1; Fig.10 This is a schematic diagram of grounding wire installation in a ballasted track section in Example 1; Fig.11 This is a diagram of grounding wire installation in a ballastless track section in Example 1; Fig.12 It is the grounding resistance calculation model of the comprehensive grounding system in Example 2; Fig.13 is a schematic diagram of grounding resistance connection of the comprehensive grounding system in Example 2; FIG14 (a) is a grounding leakage current ratio curve when the grounding device spacing is 100 m and the grounding resistance is 10 Ω in Example 2; FIG14( b ) is a curve of ground leakage current ratio when the grounding device spacing is 100 m and the grounding resistance is 20 Ω in Example 2; FIG14( c ) is a grounding leakage current ratio curve when the grounding device spacing is 100 m and the grounding resistance is 30 Ω in Example 2; FIG14( d ) is a grounding leakage current ratio curve when the grounding device spacing is 100 m and the grounding resistance is 40 Ω in Example 2; FIG15( a ) is a grounding leakage current ratio curve when the grounding device spacing is 150 m and the grounding resistance is 30 Ω in Example 2; FIG15( b ) is a curve of ground leakage current ratio when the grounding device spacing is 150 m and the grounding resistance is 35 Ω in Example 2; Fig.16 This is the grounding leakage ratio curve when the grounding device spacing is 200m and the grounding resistance is 30Ω in Example 2. DETAILED DESCRIPTION

[0018] The present invention is further described in detail below in conjunction with experimental examples and specific implementation methods. However, this should not be understood as the scope of the above subject matter of the present invention being limited to the following embodiments, and all technologies realized based on the content of the present invention belong to the scope of the present invention.

[0019] Example 1 The schematic diagram of the prior art electrical equipment and rail equipotential connection is as follows Figure 1 Take the direct supply + return power supply system commonly used in railways as an example. Figure 1Explanation: The phase line L and return line N are drawn from the secondary side of the traction substation, where the phase line L is connected to the overhead line, the return line N is connected to the rail, and the return line N is also connected to the traction substation grounding grid and the total equipotential grounding terminal board ( Figure 1 , which is not shown in the figure, and is a prior art). Since a large value of traction return current flows on the rails and there is impedance on the rails, the voltage drop between the total equipotential terminal board of the traction substation and the grounding point on the rails of the equipment facility 1 at a certain distance is U1, and U1 is also the ground potential of the equipment facility 1. The voltage between the grounding point on the rails of the equipment facility 1 and the equipment facility 2 is U2, so the ground potential of the equipment facility 2 is U1+U2, and so on. The equipment facilities 3, 4, 5, ..., n connected to the rails in sequence have ground potentials of U1+U2+U3, U1+U2+U3+U4, U1+U2+U3+U4+U5, ..., U1+U2+U3+U4+U5+...+Un. There is a signal transmission cable connecting the equipment facility 1 and the equipment facility 2, and there is a potential difference between the two (U1+U2)-U1=U2. Since this potential difference exists on the signal transmission cable and the power frequency current will flow through, it will cause strong electromagnetic interference. Therefore, although the rails serve as the common ground wire of the comprehensive grounding system, electrical equipment and facilities cannot be directly connected to the rails at the same potential.

[0020] The schematic diagram of the electrical equipment and facilities in the prior art being connected to the corresponding grounding flat steel with equal potential according to the strong and weak currents is shown in the figure below. Figure 2 shown. Figure 2 The connection method in the figure is a common grounding scheme in the field of urban rail transit under the DC traction power supply system. That is, one strong and one weak grounding flat steel is laid along the line. The grounding flat steel is connected to the station grounding grid at the station. The electrical equipment is connected to the corresponding grounding flat steel according to the strong and weak currents. For the comprehensive grounding system of urban rail transit under the AC traction power supply system, reference is also made to Figure 2Method. The reference potential of strong and weak electricity is the station grounding grid. At point b, which is far away from the traction substation, there is strong and weak electricity grounding of electrical equipment and facilities, and its control system is connected to the rails. There is a large-amplitude traction return current IG flowing through the rails. Since the grounding flat steel is only connected to the ground grid at a single point at the station, only small-amplitude stray currents IQ and IR act on the grounding flat steel through electromagnetic coupling, and their values ​​are much smaller than IG. According to Ohm's law U=IR, since IG is much larger than IQ and IR, and IG is compared with the rails and the grounding flat steel R, R can be ignored. Same as in Example 1, the potential of the rail at b (b0) is U0, and the potentials of the strong and weak electricity equipment and facilities at b (b1 and b2) are U1 and U2 respectively, so U0 is much larger than U1 and U2. At the same time, the control system of the strong and weak electricity equipment and facilities is connected to the rails. Therefore, there is a high potential difference between the rails and the strong and weak electricity equipment and facilities, which not only causes electromagnetic interference to the equipment and facilities and cannot work normally, but also there may be dangerous contact voltages on the grounding flat steel, endangering the safety of railway operation and maintenance personnel. Railway grounding systems include two types: one is the strong current grounding system mainly for traction power supply, and the other is the weak current grounding system mainly for communication signals. The strong current grounding device uses the structural steel bars in the civil structure of the bridge and tunnel as the grounding body, while the weak current grounding device uses a small amount of artificial grounding bodies separately laid in the tunnel cavern, not the civil structure steel bars. The grounding devices of the above grounding systems are separate and not connected to the same potential, so there is a dangerous potential difference, and the above-mentioned dangerous voltage problem will still occur. The specific reasons are the same as those in Example 1.

[0021] Based on Figure 1 and Figure 2 According to the analysis, the technical problem that needs to be solved is how to overcome the problem of uneven potential after using steel rails instead of through-ground wires.

[0022] A schematic diagram of an equipotential connection method for electrical equipment in a comprehensive grounding system without track circuits in a section Figure 3As shown. Grounding devices are set up along the rails at a certain distance. The grounding devices and the rails are connected at a single point, that is, the grounding devices and the rails are connected through conductors. There is only one intersection between the conductor and the rails, and there is also only one intersection between the conductor and the grounding device. Electrical equipment facilities 1 and electrical equipment facilities 2 are connected to the grounding devices respectively. The potential difference between electrical equipment facilities 1 and 2 is U2. However, since the grounding devices and the rails are connected at a single point, no loop will be formed between the grounding devices and the rails. A signal transmission line is also connected between electrical equipment facilities 1 and electrical equipment facilities 2. Therefore, even if a loop is formed, it is only formed between the grounding devices, electrical equipment facilities 1 and electrical equipment facilities 2. The rails, electrical equipment facilities 1 and electrical equipment facilities 2 will not form a loop under any circumstances. The grounding device will not have a large value of traction return current flowing through the rails. According to Ohm's law, there is no potential difference, that is, U2=0. Therefore, there is no dangerous potential difference between electrical equipment facilities 1 and 2, and there is no problem of electromagnetic interference and dangerous contact voltage. The grounding device forms an equal potential between the connection points on the rails, eliminating the potential difference formed by the direct connection of electrical equipment and facilities to the rails, and solving the signal interference caused by the potential difference in the prior art.

[0023] Furthermore, the equivalent impedance of the equivalent grounding resistance of the integrated grounding system is composed of a chain loop consisting of the impedance of the common ground line and the impedance of the grounding devices configured along the line on both sides. It can be imagined that an AC current source I is applied at a certain point, and the current forms a loop through the lead-out line, the common ground line, the grounding device and the earth. The ratio of U to I is the grounding resistance value of the integrated grounding system. The grounding device is set along the rail. After simulation calculation, the spacing between the grounding devices is set at a spacing of 150m. Each grounding device is connected to the rail through a conductor and has only one intersection. Electrical equipment and facilities can be directly connected to the grounding device, and the number of connections and spacing are not limited.

[0024] As a preferred solution, the grounding device is a structural ground formed by a reinforced concrete structure of a bridge or a tunnel.

[0025] The grounding device is a general term for the grounding wire, grounding terminal and grounding body, and the most important one is the grounding body. There are two types of grounding bodies. One is the artificial grounding body added by people, and the other is to use the original steel bars in the civil reinforced concrete as the natural grounding body without adding artificial grounding bodies. The comprehensive grounding system makes full use of the large number of structural steel bars in the civil structures of bridges and tunnels as natural grounding bodies. For bridges, generally each span of the beam (32m) or four 32m sections connected (not more than 150m) is regarded as a grounding device, and each 150m section of the tunnel is regarded as a grounding device.

[0026] As a preferred solution, the grounding device is a grounding steel bar, and the resistance of the grounding steel bar is not greater than 1Ω. That is, the grounding resistance of the system is not greater than 1Ω at any point, and the equivalent grounding resistance of the comprehensive grounding system is the equivalent impedance of any point on the common ground line, that is, the grounding resistance of the comprehensive grounding system.

[0027] The rail serves as the common ground wire of the comprehensive grounding system. The electrical equipment and facilities are connected to the rail at the same potential through the grounding device. Furthermore, the grounding terminals in the bridge and tunnel sections have been adaptively improved: the grounding terminal on the small mileage side of the bottom of the communication signal cable trough in the bridge section is cancelled, and one grounding terminal is added at the large and small mileage positions on the line side of the protective wall respectively, which is used for the equipotential connection between the sections of the bridge grounding device and between the grounding device and the rail. The setting of the grounding terminal on the small mileage side of the bridge section has changed before and after. The schematic diagram of the setting of the grounding terminal on the small mileage side of the bridge section before the change is shown in Figure 4 (a); the schematic diagram of the setting of the grounding terminal on the small mileage side of the bridge section after the change is shown in Figure 4 (b). The setting of the grounding terminal on the large mileage side of the bridge section has changed. The schematic diagram of the setting of the grounding terminal on the large mileage side of the bridge section before the change is shown in Figure 5 (a); the schematic diagram of the setting of the grounding terminal on the large mileage side of the bridge section after the change is shown in Figure 5 (b). The beam grounding device is connected to the rail once every 150m or less, that is to say, the 4-span 32m beams are connected in series through the grounding terminals on the small and large mileage sides through stainless steel connecting wires. The connection with the rail is only made through the grounding terminal at a small mileage of 150m. There is no connection with the rail within the 150m beam range, which is the so-called single-point connection. The cross-sectional diagram of the bridge grounding device and the rail connection is shown in the figure below. Figure 6 .

[0028] The grounding terminal on the short-distance side of the bottom of the communication signal cable trough is cancelled in the tunnel section, and a grounding terminal is added on the line side of the protective wall for equipotential connection with the rail. The schematic diagram of the change of the grounding terminal setting in the tunnel section is shown in Figure 7 (a) and Figure 7 (b). Figure 7 (a) is a schematic diagram of the tunnel section before the grounding terminal is set, and Figure 7 (b) is a schematic diagram of the tunnel section after the grounding terminal is set. The longitudinal grounding steel bars connect a large number of grounding steel bars in a single construction section in the tunnel. The longitudinal grounding steel bars are disconnected once every 150m, and the adjacent 150m grounding devices are electrically disconnected. A grounding terminal welded to the longitudinal grounding steel bar is provided on the starting side of the longitudinal grounding steel bar. The grounding terminal is directly connected to the rail through a grounding wire. There is no connection with the rail within the 150m tunnel range, that is, the 150m beam body grounding device is connected to the rail at a single point. The grounding device in the tunnel is connected to the rail at a single point of 150m. The comprehensive grounding stereoscopic system diagram is shown in the figure below. Figure 8 The cross-sectional diagram of the connection between the grounding device and the rail is shown in Fig. 9 shown.

[0029] The equipotential connection between the bridge and tunnel grounding devices and the rails is made of nails, and the connection wire is made of galvanized steel strands. In the ballasted track section, a special capacitor pillow is used to set the equipotential connection wire in the protection groove, and in the ballastless track section, a clamp and chemical anchor bolt are directly used to fix it on the ballastless track plate. The schematic diagram of the grounding wire installation in the ballasted track section is shown in the figure below. Fig.10 The installation diagram of grounding wire in ballastless track section is shown in Fig.11 shown.

[0030] In order to avoid the potential difference caused by the unbalanced traction return current on the grounding wire, the grounding wire uses two stainless steel connecting wires with equal resistance, one long and one short.

[0031] Example 2 The grounding device is electrically connected to the rail at a single point at a preset distance. The preset distance is 150m. The calculation basis is: The grounding resistance of the comprehensive grounding system specified in the Technical Specifications for Railway Lightning Protection and Grounding Engineering TB10180-2016 is not greater than 1Ω, that is, the grounding resistance of the system is not greater than 1Ω at any point. The equivalent grounding resistance of the comprehensive grounding system is the equivalent impedance of any point on the common ground line, that is, the grounding resistance of the comprehensive grounding system. The calculation model of the grounding resistance of the comprehensive grounding system is as follows: Fig.12 As shown, I is the current injected into the grounding device, V is the potential of the grounding device at the injection point relative to infinity, Fig.12 There are N grounding devices in total. Current I is injected from the middle and split to both sides. The current on each side is I / 2. The number of grounding devices on each side is N divided by 2. The subscript of the grounding device on the left side of the middle is N / 2. As you go to the left side of the figure, the subscript decreases by 1. Therefore, the current of the grounding device on the left side of the figure is I N / 2 ,I N / 2-1 ,I N / 2-2 ..., the current on the far left of the figure is I1, and similarly, the current of the grounding device on the right side of the figure is I N / 2+1 ,I N / 2+2 ……I N , correspondingly, the voltage of the grounding device on the left side of the figure is V N / 2 、V N / 2+1 、V N / 2+2 , ... V1, the voltages of the grounding devices on the right side of the figure are V N / 2+1 、V N / 2+2 、V N / 2+3 , ……V N The equivalent impedance is composed of a chain loop consisting of the impedance of the common ground wire configured within the effective range and the impedance of the grounding devices configured along the line on both sides. It can be imagined that after the rail replaces the through ground wire, an AC current source I is applied to a certain point on the rail, and the current forms a loop through the lead-out wire, the common ground wire, the grounding device and the earth. The ratio of U to I is the grounding resistance value of the comprehensive grounding system.

[0032] First, the spacing between grounding bodies and the grounding resistance of the grounding bodies are taken as analysis variables to analyze the impact of variable changes on the effective leakage range and grounding resistance of the grounding system. In the model, the grounding body is equivalent to a standard hemispherical model so that the shielding effect between different grounding bodies can be analyzed through a standardized model. In order to be close to the state of the actual grounding system, the model calculation considers the self-resistance of the horizontal conductor connecting the grounding body, as well as the shielding effect between different grounding bodies (that is, the mutual resistance effect between grounding bodies). In practice, the horizontal connecting line and the grounding body form a grid-type resistance network. The simulation calculation process can be performed cyclically through programming. But in practice, the horizontal connecting line and the grounding body form a grid-type resistance network. The schematic diagram of the grounding resistance connection of the comprehensive grounding system is shown in the figure Fig.13 In the figure, R is the resistance of the grounding device, and r is the grounding resistance of the through-ground wire at a certain length. The grounding resistance of a single grounding device is 10Ω, 20Ω, and 30Ω as specified in the Railway Electric Traction Power Supply Design Specification TB10009-2016. In order to compare with the critical value, 35Ω and 40Ω gears are added.

[0033] ① When the distance between grounding devices is 100m and the grounding resistance of a single grounding device changes, the relationship between the single grounding device and the leakage current ratio curve and the grounding resistance of the comprehensive grounding system are obtained. When the grounding resistance is 10Ω, 20Ω, 30Ω, and 40Ω, the leakage current ratio curves under different grounding resistance conditions are shown in Figures 14 (a), 14 (b), 14 (c), and 14 (d).

[0034] From the results, it can be seen that when the grounding resistance is 10Ω and the spacing is 100m, a total of 72 grounding bodies around the current injection point of the grounding system bear 95% of the leakage ratio in the entire grounding system (200 grounding bodies), that is, the range of the grounding system near the current injection point that truly plays an effective leakage role is 7.2 kilometers.

[0035] When the grounding resistance is 20Ω and the spacing is 100m, a total of 98 grounding bodies around the current injection point of the grounding system bear 95% of the leakage ratio in the entire grounding system (200 grounding bodies), that is, the range of the grounding system near the current injection point that truly plays an effective leakage role is 9.8 kilometers.

[0036] When the grounding resistance is 30Ω and the spacing is 100m, a total of 118 grounding bodies around the current injection point of the grounding system bear 95% of the leakage ratio in the entire grounding system (200 grounding bodies), that is, the range of the grounding system near the current injection point that truly plays an effective leakage role is 11.8 kilometers.

[0037] When the grounding resistance is 40Ω and the spacing is 100m, a total of 134 grounding bodies around the current injection point of the grounding system bear 95% of the leakage ratio in the entire grounding system (200 grounding bodies), that is, the range of the grounding system near the current injection point that truly plays an effective leakage role is 13.4 kilometers.

[0038] In summary, the effective leakage range under different grounding resistances can be obtained, which also proves that the calculation of the grounding resistance of the comprehensive grounding system is not a so-called simple proportional relationship. Table 1 shows the relationship between different grounding resistances of a single grounding device and the grounding resistance of the comprehensive grounding system.

[0039] Table 1 Relationship between different grounding resistances of a single grounding device and the grounding resistance of the comprehensive grounding system (grounding device spacing 100m) ② When the distance between grounding devices is 150m and the grounding resistance of a single grounding device changes, the relationship between the single grounding device and the leakage current ratio curve and the grounding resistance of the comprehensive grounding system can be obtained. When the grounding resistance is 30Ω and 35Ω, the leakage current ratio curves under different grounding resistances are shown in Figure 15 (a) and Figure 15 (b).

[0040] From the results, it can be concluded that when the grounding resistance is 30Ω and the spacing is 150m, a total of 93 grounding bodies around the current injection point of the grounding system bear 95% of the leakage ratio in the entire grounding system (200 grounding bodies), that is, the range of the grounding system near the current injection point that truly plays an effective leakage role is 9.3 kilometers.

[0041] When the grounding resistance is 35Ω and the spacing is 150m, a total of 99 grounding bodies around the current injection point of the grounding system bear 95% of the leakage ratio of the entire grounding system (200 grounding bodies), that is, the range of the grounding system near the current injection point that truly plays an effective leakage role is 9.9 kilometers.

[0042] Table 2 Relationship between different grounding resistances of a single grounding device and the grounding resistance of the comprehensive grounding system (grounding device spacing 150m) ③ When the distance between grounding devices is 200m and the grounding resistance of a single grounding device changes, the relationship between the single grounding device and the leakage current proportion curve and the grounding resistance of the comprehensive grounding system is obtained. When the grounding resistance is 30Ω, the grounding body leakage current proportion curve is as follows: Fig.16 shown.

[0043] From the results, it can be concluded that when the grounding resistance is 30Ω and the spacing is 200m, there are a total of 78 grounding bodies around the current injection point of the grounding system, which bear 95% of the leakage ratio in the entire grounding system (200 grounding bodies), that is, the effective leakage range in the area near the current injection point of the grounding system is 7.8 kilometers. At this time, the grounding resistance of the grounding system is 1.1083Ω.

[0044] According to the provisions of the Railway Lightning Protection and Grounding Engineering Technical Specifications TB10180-2016 that the grounding resistance of the comprehensive grounding system shall not exceed 1Ω and the Railway Electric Traction Power Supply Design Specifications TB10009-2016 that the maximum grounding resistance of the contact network shall not exceed 30Ω, based on the above analysis, the grounding device should be connected to the rail once at a distance of no more than 150m, that is, the bridge should be connected to the comprehensive grounding system at a single point of 4 spans (32x4m), and the continuous beam should be connected to the comprehensive grounding system at a distance of no more than 150m; the tunnel section should be connected to the comprehensive grounding system at a single point of no more than 150m.

[0045] The grounding device is connected to the rail every 150m, which greatly improves the range compared with the current specifications that bridge grounding devices should be connected every 32m and tunnel grounding devices should be no more than 100m. To a certain extent, it not only reduces the impact of rail drilling on rail stability, but also reduces grounding parts, construction difficulty and operation and maintenance workload, with significant economic and social benefits.

[0046] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for equipotential connection of electrical equipment in a comprehensive grounding system without track circuits in a section, characterized in that: The following steps are involved: In the bridge and tunnel sections of the railway, steel rails are used instead of through ground wires as common ground wires. The grounding device is electrically connected to the steel rails at a single point at a preset distance, and the electrical equipment is electrically connected to the grounding device.

2. The method for equipotential connection of electrical equipment in a comprehensive grounding system of a section without track circuits as claimed in claim 1, characterized in that: The grounding device comprises a grounding wire, a grounding terminal and a grounding body. The grounding body is connected to the grounding wire and the grounding terminal respectively. The grounding wire is used to connect to the rails, and the grounding terminal is used to connect to electrical equipment and facilities.

3. The method for equipotential connection of electrical equipment in a comprehensive grounding system of a section without track circuits as claimed in claim 2, characterized in that: Add two grounding terminals on both sides of the line for each span of the bridge, add two grounding terminals on the protective walls on both sides of the line every 100m in the tunnel, and cancel the grounding terminals at the bottom of the communication signal cable troughs on the bridge and tunnel.

4. The method for equipotential connection of electrical equipment in a comprehensive grounding system of a section without track circuits as claimed in claim 2, characterized in that: The equipotential connection between the bridge and tunnel grounding devices and the rails is of the nail type, and the connecting wire is galvanized steel stranded wire.

5. The method for equipotential connection of electrical equipment in a comprehensive grounding system of a section without track circuits as claimed in claim 2, characterized in that: In ballasted track sections, special capacitor pillows are used to place the equipotential connecting wire in the protective groove, and in ballastless track sections, clamps and chemical anchors are used to directly fix it to the ballastless track slab.

6. The method for equipotential connection of electrical equipment in a comprehensive grounding system of a section without track circuits as claimed in claim 2, characterized in that: The grounding wire uses two stainless steel connecting wires of equal resistance, one long and one short.

7. The method for equipotential connection of electrical equipment in a comprehensive grounding system of a section without track circuits as claimed in claim 2, characterized in that: The grounding body includes an artificial grounding body and a natural grounding body, and the natural grounding body includes steel bars in civil reinforced concrete.

8. The method for equipotential connection of electrical equipment in a comprehensive grounding system of a section without track circuits as claimed in claim 7, characterized in that: The steel bars in the civil engineering reinforced concrete include structural steel bars in the civil engineering structures of bridges and tunnels.

9. The method for equipotential connection of electrical equipment in a comprehensive grounding system of a section without track circuits as described in any one of claims 1 to 4, characterized in that: The preset distance is 150m.

10. The method for equipotential connection of electrical equipment in a comprehensive grounding system of a section without track circuits as claimed in claim 1, characterized in that: The electrical equipment includes axle counting equipment, communication optical cables, electronic information equipment in communication signal towers, and electronic information equipment in repeater station buildings.

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