Grounding structure of platform type transformer substation

Abstract

The utility model discloses a grounding structure of a platform type transformer substation, which comprises a first-stage overhead platform ground screen, a second-stage overhead platform ground screen and a pile foundation grounding leading-down part, and is characterized in that the first-stage overhead platform ground screen is positioned above the second-stage overhead platform ground screen; the first-stage overhead platform ground screen and the second-stage overhead platform ground screen are connected with a rare earth alloy embedded in a wall through a structural beam, the first-stage overhead platform ground screen and the transformer substation are grounded through the pile foundation grounding downlead, and the second-stage overhead platform ground screen is supported through the structural beam of the transformer substation and a wall body. According to the utility model, grounding materials can be effectively saved, and a good voltage-sharing effect is achieved.

Description

Technical Field

[0001] The utility model relates to a transformer substation, in particular to a platform type transformer substation grounding structure. Background Art

[0002] With the rapid development of industrialization and the acceleration of urban construction in my country, the selection of substation sites is restricted by urban planning, making land acquisition difficult and the available floor area smaller and smaller, resulting in a more compact overall layout of substations. From this background, it can be seen that in the construction of substations, determining the grounding structure is a very important link. The existing grounding structure is mostly mechanically connected by the main grounding grid buried deep in the surface layer, and the main grounding is used to unify the current. The compact layout platform grading scheme of the substation is not taken into account. The amount of wire required for grounding is large, the voltage balancing effect is poor, and it is difficult to ensure the safety of people and equipment in the station. Utility Model Content

[0003] In view of the defects of the prior art, the present invention provides a platform-type substation grounding structure.

[0004] A platform type substation grounding structure includes a primary overhead platform grounding grid, a secondary overhead platform grounding grid and a pile foundation grounding lead, wherein the primary overhead platform grounding grid and the secondary overhead platform grounding grid are connected to a pre-buried rare earth alloy in a wall through a structural beam, the primary overhead platform grounding grid and the substation are grounded through the pile foundation grounding lead, and the secondary overhead platform grounding grid is supported by the structural beam and wall of the substation.

[0005] Optionally, the primary overhead platform grounding network of the substation is connected to the secondary overhead platform grounding network through structural beams and pre-embedded rare earth alloys in the wall to form a composite three-dimensional grounding system for the entire station. The composite three-dimensional grounding system is led down to 2.5m below the surface soil through pile foundation grounding, so that the rare earth alloy is grounded; the power distribution equipment in the substation is grounded through the primary overhead platform grounding network or the secondary overhead platform grounding network.

[0006] The beneficial effect of this new type is that the grounding structure of this new type does not need to set up an additional main grounding grid in the soil layer. It only needs to lead the platform grounding grid down to 2.5m below the surface soil through the pile foundation grounding, and the connection between them is not considered. After comparative analysis, the whole station establishes a unified public main grounding grid. This utility model reduces investment, can effectively save grounding materials, has a good pressure equalization effect, ensures the safety of people and equipment in the station, and also ensures the personal safety of people in the lower social level of the platform who can enter and exit the area. It is an economical and reasonable arrangement method. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a cross-sectional view of the grounding structure of the platform-type substation of the utility model;

[0008] Figure 2 It is a three-dimensional layout diagram of a composite stereo grounding system of an embodiment of a grounding grid layout scheme of a platform-type substation of the utility model;

[0009] Figure 3 It is a simulated ground potential rise color block diagram of a composite three-dimensional grounding system of an embodiment of the grounding grid arrangement scheme of a platform-type substation of the utility model;

[0010] Figure 4 It is a color block diagram of simulated contact potential rise of a composite three-dimensional grounding system of an embodiment of the grounding grid arrangement scheme of a platform-type substation of the utility model;

[0011] Figure 5 It is a color block diagram of simulated step potential rise of a composite three-dimensional grounding system of an embodiment of the grounding grid arrangement scheme of a platform-type substation of the utility model.

[0012] Description of reference numerals:

[0013] 1. Secondary overhead platform grounding grid; 2. Primary overhead platform grounding grid; 3. Pre-embedded rare earth alloy; 4. Pile foundation grounding lead-in. DETAILED DESCRIPTION

[0014] In order to make the above-mentioned purpose, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings, so that the above-mentioned and other purposes, features and advantages of the present invention will be clearer. The same reference numerals in all the drawings indicate the same parts. The drawings are not deliberately drawn to scale, and the focus is on illustrating the main purpose of the present invention.

[0015] Reference Figure 1 , Figure 2 The grounding structure of the new platform substation includes a primary overhead platform grounding grid 2, a secondary overhead platform grounding grid 1 and a pile foundation grounding lead 4. The primary overhead platform grounding grid 2 is located above the secondary overhead platform grounding grid 1. The primary overhead platform grounding grid 2 is connected to the secondary overhead platform grounding grid 1 through structural beams and rare earth alloy 4 pre-buried in the wall. The primary overhead platform grounding grid 1 is led down to 2.5m below the surface soil through the substation pile foundation grounding, so that the composite three-dimensional grounding system is grounded.

[0016] This new platform substation grounding structure uses platform-type upper and lower combined grounding grids, pile foundation grounding and other resistance reduction measures to build a composite three-dimensional grounding system for the entire station; after the combined grounding grid is optimized, the 220kV distribution device platform grounding grid is connected to the 500kV distribution device, main transformer and 35kV reactive compensation area platform grounding grid through the structural beam and the pre-buried rare earth alloy grounding material in the wall. No additional main grounding grid is set up in the soil layer, and only the platform grounding grid is considered to be led down to 2.5m below the surface soil through the pile foundation grounding, and the connection between them is not considered. In this way, on the one hand, when making the main grounding grid of the entire station, there is no need to destroy the original landform and reduce environmental damage. On the other hand, the main grounding grid interconnection in the soil layer is reduced, achieving energy saving and material reduction. The vertical grounding arranged by 4-pile foundation grounding of the overhead platform is adopted to optimize the main grounding grid of the surface layer, and truly optimize the layout of the grounding grid.

[0017] The first-level overhead platform grounding grid 2 and the second-level overhead platform grounding grid 1 are arranged in the upper and lower layers, and the pile foundation grounding leads down 4 and other resistance reduction measures are taken to build a composite three-dimensional grounding system for the entire station. The layout, structure, and steel bar configuration of the building are adopted, and the natural grounding electrode is used as the grounding grid.

[0018] According to GB / T 50065-2011 Grounding Design Specification for AC Electrical Installations, electrical installations or equipment with different uses and rated voltages in substations should use a total grounding grid unless otherwise specified. The grounding resistance of the grounding grid should meet the minimum requirements. General requirements for grounding grid design for power plants and substations of 110kV and above: The size and structure of the grounding grid should be preliminarily formulated based on the soil structure and resistivity of the site, as well as the required grounding resistance value of the grounding grid. The grounding resistance value and ground potential rise of the grounding grid should be obtained through numerical calculations, and compared with the required limit values, and the grounding grid design should be modified to meet the requirements. Designers should obtain the contact potential difference and step potential difference distribution of the ground surface through calculations, and should compare the maximum contact potential difference and the maximum step potential difference with the allowable values. If the requirements are not met, measures to reduce the value or to increase the allowable value should be taken.

[0019] According to GB50065 "Grounding Design Specifications for AC Electrical Installations", the grounding resistance of the grounding grid of power plants and substations for protective grounding requirements should meet the following requirements

[0020]

[0021] Where: R—maximum grounding resistance with seasonal changes (Ω)

[0022] I G —Maximum short-circuit current to ground when a system fault occurs (A).

[0023] When the grounding resistance of the grounding grid does not meet the requirements, the grounding resistance can be appropriately increased through technical and economic comparison. When it meets the provisions of GB50065 "Grounding Design Specifications for AC Electrical Installations", the ground potential of the grounding grid can be increased to 5kV. If necessary, after special calculations and when the measures taken can ensure the safety and reliability of personnel and equipment, the ground potential of the grounding grid can be further increased.

[0024] When single-phase grounding or two-phase grounding at the same point occurs in the 110kV and above effective grounding system and the 6kV to 35kV low-resistance grounding system, the contact potential difference and step potential difference of the grounding grid of the power plant and substation should not exceed the value calculated by the following formula:

[0025] Step potential difference limit:

[0026]

[0027] Contact potential difference limit:

[0028]

[0029] Where: U t —Allowable value of contact potential difference (V).

[0030] U s —Allowable value of step potential difference (V).

[0031] p s —Resistivity of the surface layer (m).

[0032] C s —Surface attenuation coefficient.

[0033] t s —Duration of ground fault current (s).

[0034] According to the above requirements, CDEGS software is used to simulate the grounding structure of the utility model. The simulation results refer to Figure 3 , Figure 4 , Figure 5 ,from Figure 3 , Figure 4 , Figure 5 It can be seen that the ground potential rise at all locations in the entire station is less than 5kV, and the contact potential and step voltage meet the above safety limits.

[0035] Through the above analysis, it can be seen that the new grounding structure does not need to set up an additional main grounding grid in the soil layer. It only needs to lead the platform grounding grid to 2.5m below the surface soil through the pile foundation grounding, and the connection between them is not considered. After comparative analysis, the whole station establishes a unified public main grounding grid. The utility model reduces investment, can effectively save grounding materials, has a good pressure equalization effect, ensures the safety of people and equipment in the station, and also ensures the personal safety of people in the lower social level of the platform who can enter and exit the area. It is an economical and reasonable arrangement method.

[0036] Many specific details are described in the above description to facilitate a full understanding of the present invention. However, the above description is only a preferred embodiment of the present invention. The present invention can be implemented in many other ways different from those described herein, so the present invention is not limited by the specific implementation disclosed above. At the same time, any person familiar with the technical field can make many possible changes and modifications to the present technical solution using the methods and technical contents disclosed above without departing from the scope of the present technical solution, or modify it into an equivalent embodiment of equivalent changes. Any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the present technical solution still falls within the scope of protection of the present technical solution.

Claims

1. A platform type substation grounding structure, characterized in that: It includes a primary overhead platform grounding grid, a secondary overhead platform grounding grid and a pile foundation grounding lead, wherein the primary overhead platform grounding grid is located above the secondary overhead platform grounding grid, the primary overhead platform grounding grid and the secondary overhead platform grounding grid are connected to the pre-buried rare earth alloy in the wall through structural beams, the primary overhead platform grounding grid and the substation are grounded through the pile foundation grounding lead, and the secondary overhead platform grounding grid is supported by the structural beams and walls of the substation.

2. The grounding structure according to claim 1, characterized in that: The primary overhead platform grounding network of the substation is connected to the secondary overhead platform grounding network through structural beams and pre-embedded rare earth alloys in the wall to form a composite three-dimensional grounding system for the entire station. The composite three-dimensional grounding system is led down to 2.5m below the surface soil through pile foundation grounding, so that the rare earth alloy is grounded.

3. The grounding structure according to claim 1, characterized in that: The power distribution device in the substation is grounded through the primary overhead platform grounding network or the secondary overhead platform grounding network.

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