Alternating current substation ground system
By designing a grounding system consisting of a first horizontal grounding grid and a second horizontal grounding grid in the AC substation, combined with vertical grounding electrodes and an asphalt concrete layer, the problems of ground potential rise and excessive contact voltage and step voltage in the grounding system were solved, thereby improving system safety and equipment operation stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHINA ENERGY CONSTR GRP SHAANXI ELECTRIC POWER DESIGN INST CO LTD
- Filing Date
- 2023-05-31
- Publication Date
- 2026-07-10
Smart Images
Figure CN116454648B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of power technology, and more particularly to a grounding system in an AC substation. Background Technology
[0002] In AC substations, the grounding system is used to reliably ground electrical equipment and connect it into a network below the ground to protect the safety of people and electrical equipment.
[0003] However, in current AC substation grounding systems, when power equipment fails, local ground potential rise values may exceed allowable values, as may contact voltage and step voltage values in local areas, affecting the operation of power equipment and grounding systems, as well as personal safety. Summary of the Invention
[0004] This application provides a grounding system for AC substations that can improve the safety of the grounding system in AC substations.
[0005] In one aspect, a grounding system for an AC substation is provided, comprising a first horizontal grounding grid, a second horizontal grounding grid, a plurality of first vertical grounding electrodes, and a plurality of second vertical grounding electrodes;
[0006] The first horizontal grounding grid includes multiple first horizontal grounding electrodes, which form multiple first grids parallel to the ground.
[0007] The second horizontal grounding grid includes multiple second horizontal grounding electrodes, which form multiple second grids parallel to the ground. The second horizontal grounding grid is located on the side of the first region away from the ground around the fault current inflow point. The second region where the first horizontal grounding grid is located includes the first region.
[0008] Multiple first vertical grounding electrodes are used to connect a portion of the first horizontal grounding grid located in the first region and the second horizontal grounding grid, as well as to connect a portion of the first horizontal grounding grid located in the second region other than the first region with the soil;
[0009] Multiple second vertical grounding electrodes are used to connect the second horizontal grounding grid to the soil.
[0010] In one feasible design, the outer boundary of the first grid at the top corner of the first horizontal grounding grid is set as an arc.
[0011] In one feasible design, an asphalt concrete layer is provided on the side of the first horizontal grounding grid near the ground at the top corner position. The projection area of the asphalt concrete layer on the first horizontal grounding grid includes the area where the first grid at the top corner position of the first horizontal grounding grid is located.
[0012] In one feasible design, the first area of the first grid of the first horizontal grounding grid in the first region is smaller than the second area of the first grid of the first horizontal grounding grid in the second region other than the first region.
[0013] In one feasible design, the area of the second grid is set to the area of the first grid.
[0014] In a feasible design, the second area is four times the size of the first area.
[0015] In one feasible design, the distance between the first horizontal grounding grid and the second horizontal grounding grid is equal to the side length of the first grid in the first region.
[0016] In one feasible design, the first grid is set as a square, and the angle corresponding to the arc is 90 degrees.
[0017] In one feasible design, one end of the first vertical grounding electrode is connected to the vertex of the first grid, and the other end of the first vertical grounding electrode is connected to the vertex of the second grid or laid in the ground.
[0018] In one feasible design, one end of the second vertical grounding electrode is connected to the vertex of the second grid, and the other end of the second vertical grounding electrode is laid in the ground.
[0019] When a ground fault occurs in the electrical equipment of an AC substation, the ground potential at a predetermined distance from the fault current inlet is generally considered to be 0. Therefore, the ground potential distribution near the fault current inlet gradually decreases from high to low, eventually reaching 0. Because the voltage of the electrical equipment in an AC substation is very high, the rise in ground potential around the fault current inlet can exceed permissible values, seriously affecting the operation of the electrical equipment and grounding system, as well as personal safety.
[0020] According to the specifications in GB / T 50065-2011, the resistance value of a grounding grid with a mesh structure is shown in the following formula (1):
[0021]
[0022] Where S is the area of the grounding grid, ρ is the soil resistivity, and R is the resistance value.
[0023] In this embodiment, a second horizontal grounding grid 120 is installed on the side of the first region surrounding the fault current ingress point of the first horizontal grounding grid 110 that is away from the ground. A first vertical grounding electrode 130 connects the portion of the first horizontal grounding grid located in the first region to the second horizontal grounding grid 120, thereby increasing the grounding grid area around the fault current ingress point. The increased area is the area of the second horizontal grounding grid 120. According to formula (1), when the grounding grid area around the fault current ingress point increases, R decreases.
[0024] According to the description in GB / T 50065-2011, the ground potential rise value is as shown in the following formula (2):
[0025] V = I G Formula (2)
[0026] Where V is the rise in ground potential, and I G The effective value of the maximum ground fault asymmetrical current entering the ground through the grounding grid, where R is the resistance value.
[0027] Therefore, a decrease in R reduces the ground potential rise V at the location where the fault current enters, thereby reducing the possibility of personal injury and electrical equipment being endangered due to excessively high ground potential rise and improving the safety of the grounding system. Attached Figure Description
[0028] To more clearly illustrate the technical solution of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0029] Figure 1 This is a schematic diagram of a grounding system in an AC substation provided in an exemplary embodiment of this application;
[0030] Figure 2 This is a schematic diagram of an AC substation site provided in an exemplary embodiment of this application;
[0031] Figure 3 This is a schematic diagram of a front view of an exemplary grounding system provided in an exemplary embodiment of this application;
[0032] Figure 4 This is a schematic diagram of an example of a first horizontal grounding grid provided in an exemplary embodiment of this application;
[0033] Figure 5 This is another example of a grounding system schematic diagram provided in an exemplary embodiment of this application;
[0034] Figure 6 This is a schematic diagram of a three-dimensional grounding system provided in an exemplary embodiment of this application.
[0035] Explanation of reference numerals in the attached figures:
[0036] 110-First horizontal grounding grid, 120-Second horizontal grounding grid, 130-First vertical grounding electrode, 140-Second vertical grounding electrode, 150-Asphalt concrete layer, 210-Main transformer area, 220-First voltage level area, 230-Second voltage level area; 240-First frame, 250-Second frame;
[0037] 111-First horizontal grounding electrode, 112-First grid, 121-Second horizontal grounding electrode, 122-Second grid. Detailed Implementation
[0038] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0039] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application; the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, unless otherwise explicitly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly, for example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication of two elements. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.
[0040] Figure 1 This is a schematic diagram of a grounding system in an AC substation provided in an exemplary embodiment of this application, as shown below. Figure 1 As shown, the grounding system includes a first horizontal grounding grid 110, a second horizontal grounding grid 120, a plurality of first vertical grounding electrodes 130 and a plurality of second vertical grounding electrodes 140;
[0041] The first horizontal grounding grid 110 includes a plurality of first horizontal grounding electrodes 111, which together form a plurality of first grids 112 parallel to the ground.
[0042] The second horizontal grounding grid 120 includes a plurality of second horizontal grounding electrodes 121, which form a plurality of second grids 122 parallel to the ground. The second horizontal grounding grid 120 is located on the side of a first region away from the ground around the fault current inflow point. The second region where the first horizontal grounding grid 110 is located includes the first region.
[0043] Multiple first vertical grounding electrodes 130 are used to connect the portion of the first horizontal grounding grid 110 located in the first region and the second horizontal grounding grid 120, as well as to connect the portion of the first horizontal grounding grid 110 located in the second region other than the first region with the soil, so that the fault current can be conducted to the ground;
[0044] Multiple second vertical grounding electrodes 140 are used to connect the second horizontal grounding grid 120 to the soil so that fault current can be conducted to the ground.
[0045] In this context, the first grid 112, which is parallel to the ground, can also be understood as the plane containing the first grid 112 being parallel to the ground. Similarly, the second grid 122, which is parallel to the ground, can also be understood as the plane containing the second grid 122 being parallel to the ground.
[0046] The fault current ingress point refers to the location where the fault current from the external line of the grounding system flows into the first horizontal grounding grid. The size of the first area surrounding the fault current ingress point can be set according to actual needs, and this application does not limit it. In addition, there can be multiple fault current ingress points, and the first area is determined based on these multiple fault current ingress points.
[0047] The materials of the first horizontal grounding electrode 111, the second horizontal grounding electrode 121, the first vertical grounding electrode 130, and the second vertical grounding electrode 140 are conductive materials.
[0048] Figure 2 This is a schematic diagram of an AC substation site provided in an exemplary embodiment of this application, as shown below. Figure 2 As shown, the AC substation site is rectangular, with sides of 300m × 200m. The site includes a main transformer area 210, a first voltage level area 220, a second voltage level area 230, and other areas. The main transformer area 210 is used to house the main transformer. The first voltage level area is used to house the corresponding voltage level distribution equipment and the first frame 240. The second voltage level area is used to house the corresponding voltage level distribution equipment and the second frame 250; the other areas house reactive power compensation equipment, low-voltage switchgear, control and protection equipment, auxiliary rooms, etc.
[0049] The grounding system in this embodiment can be laid in Figure 2 In the soil beneath the AC substation site shown. (As...) Figure 2As shown, when equipment outside the site fails, the fault current may flow into the grounding system through the structure within the site. When equipment inside the AC substation site fails, the fault current may flow into the grounding system through the grounding point of the structure or distribution equipment within the site. Therefore, the contact point between the grounding point of the structure and distribution equipment and the grounding system is the point where the fault current enters.
[0050] Figure 3 This is a schematic diagram of a front view of an exemplary grounding system provided in an exemplary embodiment of this application, as shown below. Figure 3 As shown, the second horizontal grounding grid 120 is located on the side of the first horizontal grounding grid 110 that faces away from the ground, and the portion of the first horizontal grounding grid 110 located in the first region is connected to the second horizontal grounding grid 120 via a conductor. For greater clarity, Figure 3 The mesh structure of the first horizontal grounding grid 110 and the second horizontal grounding grid 120 is omitted. Additionally, it can be seen that the direction away from the ground is perpendicular to the ground.
[0051] When a ground fault occurs in the electrical equipment of an AC substation, the ground potential at a predetermined distance from the fault current inlet is generally considered to be 0. Therefore, the ground potential distribution near the fault current inlet gradually decreases from high to low, eventually reaching 0. Because the voltage of the electrical equipment in an AC substation is very high, the rise in ground potential around the fault current inlet can exceed permissible values, seriously affecting the operation of the electrical equipment and grounding system, as well as personal safety.
[0052] According to the specifications in GB / T 50065-2011, the resistance value of a grounding grid with a mesh structure is shown in the following formula (1):
[0053]
[0054] Where S is the area of the grounding grid, ρ is the soil resistivity, and R is the resistance value.
[0055] In this embodiment, a second horizontal grounding grid 120 is installed on the side of the first region surrounding the fault current ingress point of the first horizontal grounding grid 110 that is away from the ground. A first vertical grounding electrode 130 connects the portion of the first horizontal grounding grid located in the first region to the second horizontal grounding grid 120, thereby increasing the grounding grid area around the fault current ingress point. The increased area is the area of the second horizontal grounding grid 120. According to formula (1), when the grounding grid area around the fault current ingress point increases, R decreases.
[0056] According to the description in GB / T 50065-2011, the ground potential rise value is as shown in the following formula (2):
[0057] V = I G R formula (2)
[0058] Where V is the rise in ground potential, and I G The effective value of the maximum ground fault asymmetrical current entering the ground through the grounding grid, where R is the resistance value.
[0059] Therefore, a decrease in R reduces the ground potential rise V at the location where the fault current enters, thereby reducing the possibility of personal injury and electrical equipment being endangered due to excessively high ground potential rise and improving the safety of the grounding system.
[0060] For example, the spacing between the first horizontal grounding grid 110 and the second horizontal grounding grid 120 can be set as needed.
[0061] In one feasible design, one end of the first vertical grounding electrode 130 is connected to the vertex of the first grid 112, and the other end of the first vertical grounding electrode 130 is connected to the vertex of the second grid 122 or laid in the ground.
[0062] like Figure 3 As shown, one end of the first vertical grounding electrode 130 located on one side of the first region is connected to the vertex (or intersection) of the first grid 112, and the other end is connected to the vertex (or intersection) of the second grid 122. One end of the first vertical grounding electrode 130 located on one side of the second region other than the first region is connected to the vertex of the first grid 112, and the other end is inserted into the soil to achieve grounding.
[0063] In one feasible design, one end of the second vertical grounding electrode 140 is connected to the vertex of the second grid 122, and the other end of the second vertical grounding electrode 140 is laid in the ground.
[0064] In the above example, the grounding of the second horizontal grounding network 120 is achieved through multiple second vertical grounding electrodes 140.
[0065] In one feasible design, the first vertical grounding electrode 130 and / or the second vertical grounding electrode 140 are positioned perpendicular to the ground.
[0066] Once the spacing between the first horizontal grounding grid 110 and the second horizontal grounding grid 120 is set, the first vertical grounding electrode 130 and / or the second vertical grounding electrode 140 are set vertically to the ground, which saves conductor material compared to setting them inclined to the ground.
[0067] In one feasible design, the outer boundary of the first grid 112 at the apex of the first horizontal grounding grid 110 is set as an arc.
[0068] For example, such as Figure 4 As shown, the outer boundaries of the first grid 112 at the four apex positions of the first horizontal grounding grid 110 are all set as arcs.
[0069] In one feasible design, the first grid 112 is set as a square, and the angle corresponding to the arc is 90 degrees, that is, the radius corresponding to the arc is the side length of the first grid 112.
[0070] Currently, most AC substation sites are rectangular, resulting in the grounding grid laid in the soil beneath the substation having predominantly straight edges with right angles between them. This distortion of the electric field at the edges leads to higher contact and step voltages at these edges. While the grounding grid is uniformly laid out throughout the entire AC substation, the permissible values for contact and step voltages are the same at all locations. However, the distortion of the electric field at the edges causes these voltages to exceed permissible limits, threatening the safety of workers.
[0071] In the above embodiments of this application, by setting the outer boundary of the first grid 112 at the apex of the first horizontal grounding grid 110 as an arc, the two adjacent edges of the first horizontal grounding grid 110 can be smoothly connected. Furthermore, since the outer boundary at the apex is set as an arc, the transition of the first horizontal grounding grid 110 at the edge apex is smoother, which can reduce the distortion of the electric field at the edge, thereby reducing the contact voltage and step voltage at the edge of the first horizontal grounding grid 110, making them less than the allowable values of the first horizontal grounding grid 110 for contact voltage and step voltage, and improving the safety of the grounding system.
[0072] In a feasible design, such as Figure 5 As shown, an asphalt concrete layer 150 is provided on the side of the first horizontal grounding grid 110 near the ground at the top corner. The projection area of the asphalt concrete layer 150 on the first horizontal grounding grid 110 includes the area where the first grid 112 at the top corner of the first horizontal grounding grid 110 is located.
[0073] For example, the thickness of the asphalt concrete layer 150 ranges from 10cm to 35cm, for example, it can be 20cm.
[0074] According to the description in GB / T 50065-2011, the permissible value of the contact voltage is shown in the following formula (3):
[0075]
[0076] Among them, U t1 ρ is the allowable value for contact voltage. s C represents the resistivity of the surface soil. S t is the attenuation coefficient of the surface soil. S This represents the duration of the ground fault current.
[0077] The allowable step voltage is shown in the following formula (4):
[0078]
[0079] U t2 ρ is the allowable value for step voltage. s C represents the resistivity of the surface soil. S t is the attenuation coefficient of the surface soil. S This represents the duration of the ground fault current.
[0080] The resistivity of general soil is typically tens to hundreds of Ω·m, while the resistivity of asphalt concrete layers is typically thousands of Ω·m. Combining formulas (3) and (4), it can be seen that by setting an asphalt concrete layer above the apex of the first horizontal grounding grid 110 in the above embodiments of this application, the resistivity of ρ can be increased. s This allows for an increase in the allowable values of contact voltage and step voltage at the edge of the first level grounding grid 110.
[0081] It should be noted that this application does not limit the area of the asphalt concrete layer 150, as long as it can cover the first grid 112 at the top corner of the first horizontal grounding grid 110. For example Figure 5 As shown, the asphalt concrete layer 150 can cover four first grids 112. It should be noted that if the outer boundary of the first grid 112 at the top corner of the first horizontal grounding grid 110 is set as an arc, for the sake of brevity, this application refers to the fan-shaped area at the top corner as the first grid 112.
[0082] For example, the asphalt concrete layer 150 is set as a square with a side length twice the side length of the first grid 112.
[0083] In one feasible design, the first area of the first grid 112 of the first horizontal grounding grid 110 in the first region is smaller than the second area of the first grid 112 of the first horizontal grounding grid 110 in the second region other than the first region.
[0084] In the example above, by increasing the density of the first grid 112 in the first region where the fault current access point is located, the local voltage in the fault-prone first region can be averaged, further enhancing the safety of the first horizontal grounding grid 110.
[0085] In a feasible design, the second area is four times the size of the first area.
[0086] For example, in the first region, the first grid 112 is set as a square with a side length of 10 meters (m), that is, the length of the first horizontal grounding electrode constituting the first grid 112 in the first region is 10m. In the second region, the first grid 112 of other regions besides the first region is set as a square with a side length of 20m, that is, the length of the first horizontal grounding electrode constituting the first grid 112 of the other region is 20m.
[0087] In one feasible design, the area of the second grid 122 is set as the area of the first grid.
[0088] For example, such as Figure 6 As shown, the shape and side length of the second grid 122 are the same as those of the first grid 112 in the first region. That is, the length of the second horizontal grounding electrode is the same as the length of the first horizontal grounding electrode in the first region.
[0089] For example, the length of the first horizontal grounding electrode constituting the first grid 112 in the first region is 10m, and the length of the second horizontal grounding electrode is 10m.
[0090] In one feasible design, the distance between the first horizontal grounding grid 110 and the second horizontal grounding grid 120 is equal to the side length of the first grid 112 in the first region.
[0091] like Figure 6 As shown, the distance between the first horizontal grounding grid 110 and the second horizontal grounding grid 120 is 10m, meaning the length of the first vertical grounding electrode in the first area is 10m. The length of the first vertical grounding electrode in other areas is 2.5m. The length of the second vertical grounding electrode is also 2.5m. It can be seen that after the first horizontal grounding grid 110 and the second horizontal grounding grid 120 are connected via the first vertical grounding electrode, they form a three-dimensional grid.
[0092] The basic principles of this application have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this application are merely examples and not limitations, and should not be considered as essential features of each embodiment of this application. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the application to the necessity of employing the aforementioned specific details for implementation.
[0093] It should be understood that although the steps in the flowcharts of the accompanying figures are shown sequentially as indicated by the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the accompanying figures may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times, and their execution order is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the sub-steps or stages of other steps.
[0094] The block diagrams of devices, apparatuses, devices, and systems involved in this application are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, apparatuses, devices, and systems can be connected, arranged, and configured in any manner. Words such as “comprising,” “including,” “having,” etc., are open-ended terms meaning “including but not limited to,” and are used interchangeably with them. The terms “or” and “and” as used herein refer to the terms “and / or,” and are used interchangeably with them unless the context clearly indicates otherwise. The term “such as” as used herein refers to the phrase “such as but not limited to,” and is used interchangeably with it.
[0095] It should also be noted that in the apparatus, equipment, and methods of this application, the components or steps can be disassembled and / or recombined. These disassemblies and / or recombinations should be considered as equivalent solutions of this application.
[0096] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use this application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of this application. Therefore, this application is not intended to be limited to the aspects shown herein, but rather to be accorded the widest scope consistent with the principles and novel features disclosed herein.
[0097] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of this application to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.
Claims
1. A grounding system in an AC substation, characterized in that, It includes a first horizontal grounding grid, a second horizontal grounding grid, multiple first vertical grounding electrodes, and multiple second vertical grounding electrodes; The first horizontal grounding grid includes a plurality of first horizontal grounding electrodes, which form a plurality of first grids parallel to the ground. The second horizontal grounding grid includes a plurality of second horizontal grounding electrodes, which form a plurality of second grids parallel to the ground. The second horizontal grounding grid is located on the side of a first region away from the ground around the location where the fault current enters. The second region where the first horizontal grounding grid is located includes the first region. Multiple first vertical grounding electrodes are used to connect the portion of the first horizontal grounding grid located in the first area and the second horizontal grounding grid, and to connect the portion of the first horizontal grounding grid located in the second area other than the first area with the soil; Multiple second vertical grounding electrodes are used to connect the second horizontal grounding grid to the soil; The first area of the first grid of the first horizontal grounding grid in the first region is smaller than the second area of the first grid of the first horizontal grounding grid in the second region other than the first region; An asphalt concrete layer is provided on the side of the first horizontal grounding grid near the ground at the top corner. The projection area of the asphalt concrete layer on the first horizontal grounding grid includes the area where the first grid is located at the top corner of the first horizontal grounding grid.
2. The grounding system according to claim 1, characterized in that, The outer boundary of the first grid at the top corner of the first horizontal grounding grid is set as an arc.
3. The grounding system according to claim 1, characterized in that, The area of the second grid is set to the area of the first grid.
4. The grounding system according to claim 1, characterized in that, The second area is four times the area of the first area.
5. The grounding system according to claim 1, characterized in that, The distance between the first horizontal grounding grid and the second horizontal grounding grid is equal to the side length of the first grid in the first region.
6. The grounding system according to claim 2, characterized in that, The first grid is set to a square, and the angle corresponding to the arc is 90 degrees.
7. The grounding system according to any one of claims 1-2, characterized in that, One end of the first vertical grounding electrode is connected to the vertex of the first grid, and the other end of the first vertical grounding electrode is connected to the vertex of the second grid or laid in the ground.
8. The grounding system according to any one of claims 1-2, characterized in that, One end of the second vertical grounding electrode is connected to the vertex of the second grid, and the other end of the second vertical grounding electrode is laid in the ground.