An evaluation method of additional grounding device of high resistivity wind farm area considering horizontal stratified geology

Abstract

This invention discloses an evaluation method for additional grounding devices in high-resistivity wind farm areas considering horizontally layered geology, belonging to the field of lightning protection technology for new energy power systems. It mainly includes a wind turbine foundation grounding ring, a horizontal grounding device for a prefabricated substation, a horizontal ring grounding device for the wind turbine, horizontal grounding flat steel for the wind turbine, vertical grounding electrodes, grounding connection points, orthogonal measuring lines, etc. By constructing a grounding test platform for high-resistivity wind farm areas considering layered geology, and conducting geological resistivity tests at different wind turbine locations and under different measuring lines based on the Wenner four-electrode method, the method obtains the estimation factor of the additional grounding electrode at different wind turbine locations. The test platform constructed by this invention can consider the influence of horizontally layered geology and obtain the estimation factor of the additional grounding electrode for grounding systems at different wind turbine locations, providing an engineering reference for improving the efficiency of grounding design in high-resistivity wind farm areas facing horizontally layered geology.

Description

Technical Field

[0001] This invention belongs to the field of lightning protection technology for new energy power systems, specifically relating to an evaluation method for additional grounding devices in high resistivity wind farm areas that take into account horizontally layered geology. Background Technology

[0002] Clean energy resources such as wind and solar power are constantly being explored and developed, and more and more new energy power projects are being built in areas rich in green energy resources. The Qinghai-Tibet Plateau region of my country is one of the richest regions in wind energy resources. However, the Qinghai-Tibet Plateau has seasonal permafrost, with high soil resistivity and layered geological conditions, which greatly affects the lightning protection grounding performance of new energy power systems. Therefore, how to reasonably and effectively assess the grounding performance of wind farm areas under such geological conditions is of great practical significance for power engineering construction. Currently, there is a lack of rapid and effective assessment methods for grounding protection design of wind power generation projects under high soil resistivity and layered geology. In order to improve the efficiency of survey and design, it is urgent to study the assessment method of additional grounding devices for high resistivity wind farm areas considering horizontally layered geology. This can provide engineering reference for the optimization and assessment analysis of grounding design for high resistivity wind farm areas considering horizontally layered geology. Summary of the Invention

[0003] The purpose of this invention is to address the shortcomings of existing technologies and provide an evaluation method for additional grounding devices in high resistivity wind farm areas that take into account horizontally layered geology.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: First, a grounding test platform for high resistivity wind farm areas, taking into account layered geology, is constructed. This platform includes: wind turbine generator foundation grounding ring, wind turbine generator horizontal ring grounding device, wind turbine generator horizontal grounding flat steel bar 1, wind turbine generator horizontal grounding flat steel bar 2, wind turbine generator horizontal grounding flat steel bar 3, grounding connection point 1, grounding connection point 2, grounding connection point 3, grounding connection point 4, grounding connection point 5, grounding grid lead wire, vertical grounding electrode 1, vertical grounding electrode 2, vertical grounding electrode 3, vertical grounding electrode 4, horizontal grounding flat steel bar 4, horizontal grounding flat steel bar 5, horizontal grounding flat steel bar 6, horizontal grounding flat steel bar 7, horizontal grounding flat steel bar 8, vertical grounding electrode 5, vertical grounding electrode 6, grounding connection point 6, grounding connection point 7, grounding connection point 8, grounding connection point 9, grounding connection point 10, grounding connection point 11, box-type substation horizontal grounding device, additional grounding device 1, additional grounding device 2, additional grounding device 3, additional grounding device 4, horizontal grounding flat steel bar 9, horizontal grounding flat steel bar 10, multi-layer horizontal layered wind turbine location ground, horizontal measuring line, and vertical measuring line. The wind turbine generator foundation grounding ring is electrically connected to the wind turbine generator horizontal grounding flat steel 1, 2, and 3 via grounding connection points 1, 2, and 3, respectively. The wind turbine generator horizontal ring grounding device is electrically connected to the vertical grounding electrode 1, 2, 3, and 4, respectively. Horizontal grounding flat steel 1 and 2 are electrically connected to the wind turbine generator horizontal ring grounding device via grounding connection points 4 and 5, respectively. Horizontal grounding flat steel 3 is electrically connected to the vertical grounding electrode 3. The grounding grid lead wire is electrically connected to the wind turbine generator horizontal ring grounding device via grounding connection point 5. Horizontal grounding flat steel 4 and 5 are electrically connected to the horizontal grounding flat steel via grounding connection points 8 and 10, respectively. Grounding flat steel nine and horizontal grounding flat steel ten are electrically connected; vertical grounding electrode five and vertical grounding electrode six are electrically connected to the horizontal grounding device of the box-type substation; the horizontal grounding device of the box-type substation is electrically connected to horizontal grounding flat steel seven and horizontal grounding flat steel eight through grounding connection point six and grounding connection point seven, respectively; auxiliary grounding device one and auxiliary grounding device three are electrically connected to horizontal grounding flat steel seven and horizontal grounding flat steel eight through grounding connection point eight and grounding connection point ten, respectively; auxiliary grounding device two and auxiliary grounding device four are electrically connected to horizontal grounding flat steel six through grounding connection point nine and grounding connection point eleven, respectively; horizontal grounding flat steel nine is electrically connected to auxiliary grounding device one and auxiliary grounding device two through grounding connection point eight and grounding connection point nine, respectively; horizontal grounding flat steel ten is electrically connected to auxiliary grounding device three and auxiliary grounding device four through grounding connection point ten and grounding connection point eleven, respectively. The second step involves conducting georesistivity tests at different locations and along different measuring lines using the Wenner four-electrode method: For a multi-layered horizontal wind turbine site, soil resistivity tests were conducted with different electrode spans along both horizontal and vertical survey lines. During the tests, the electrode spans selected along both horizontal and vertical survey lines were kept equal. Electrical parameters were estimated along both horizontal and vertical survey lines. The obtained soil electrical parameters for each layer of the multi-layered horizontal wind turbine site were the arithmetic mean of the estimated results along both horizontal and vertical survey lines. Finally, the optimal grounding layer depth and the corresponding soil resistivity were obtained below the frozen soil layer.

[0005] The third step involves estimating the additional grounding electrode at different wind turbine locations. This includes deriving the grounding resistance formula for a composite grounding electrode with a closed main edge based on a horizontal grounding electrode in uniform soil, and performing data fitting calculations to determine the additional grounding electrode estimation factor. K F It can be obtained from the following formula: ; in, ; In the formula η The resistance reduction factor is the additional grounding electrode. L A This is expressed as the sum of the lengths of the horizontally grounded flat steel bars. S c This represents the total horizontal area of ​​the original composite grounding grid. H The optimal burial depth for laying horizontal grounding electrodes. ρ c This represents the soil resistivity of the soil layer where the horizontal grounding electrode is laid. L W It is represented as the sum of the lengths of the outer edges of the horizontal grounding grid. b The width of the horizontally grounded flat steel. D The thickness of the horizontal grounding flat steel. K T To evaluate the coefficient parameters, according to the electrical design specifications for wind farm projects, the grounding resistance required in the above formula is based on 4 ohms.

[0006] when K F When ∈(-∞,0], it indicates that the grounding resistance of the original composite grounding device meets the requirements, and no additional grounding electrode is needed; when K F When the value is (-∞, 0), it indicates that the grounding resistance of the original composite grounding device does not meet the requirements, and additional grounding electrodes are needed. The specific number of additional grounding electrodes can be referenced from the additional grounding electrode estimation factor. K F Numeric expression retrieval.

[0007] The method provided by this invention can effectively evaluate the amount of additional grounding devices in wind turbine locations with different high resistivity, providing an engineering reference for the optimization and evaluation of grounding design in wind farm areas.

[0008] Compared with the prior art, the beneficial effects of this invention are as follows: 1) The grounding test platform for high resistivity wind farm areas constructed in this invention can effectively take into account the influence of layered geology and high resistivity, and the test platform has reliability; 2) The evaluation method in this invention can obtain the estimation factor of the additional grounding electrode based on the stratified geology of high resistivity wind farms, and can effectively evaluate the additional grounding device. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of the overall structure of the composite grounding device laying platform in the wind farm area when the present invention is used; Figure 2 This is a schematic diagram of the geological and resistivity testing of the wind farm area when this invention is used. Detailed Implementation

[0010] The present invention will now be described in further detail with reference to the accompanying drawings.

[0011] Depend on Figure 1 and Figure 2 The experimental platform and method provided by this invention include the following steps: Step 1: Establish a grounding test platform for high resistivity wind farm areas considering layered geology. This platform includes: 1. Wind turbine generator foundation grounding ring; 2. Wind turbine generator horizontal ring grounding device; 3. Wind turbine generator horizontal grounding flat steel bar one; 4. Wind turbine generator horizontal grounding flat steel bar two; 5. Wind turbine generator horizontal grounding flat steel bar three; 6. Grounding connection point one; 7. Grounding connection point two; 8. Grounding connection point three; 9. Grounding connection point four; 10. Grounding grid lead wire; 11. Vertical grounding electrode one; 12. Vertical grounding electrode two; 13. Vertical grounding electrode three; 14. Vertical grounding electrode four; 15. Horizontal grounding flat steel bar four; 16. Horizontal grounding flat steel bar… 17. Horizontal grounding flat steel 6. 18. Horizontal grounding flat steel 7. 19. Horizontal grounding flat steel 8. 20. Vertical grounding electrode 5. 21. Vertical grounding electrode 6. 22. Grounding connection point 6. 23. Grounding connection point 7. 24. Grounding connection point 8. 25. Grounding connection point 9. 26. Grounding connection point 10. 27. Grounding connection point 11. 28. Box-type substation horizontal grounding device. 29. Additional grounding device 1. 30. Additional grounding device 2. 31. Additional grounding device 3. 32. Additional grounding device 4. 33. Horizontal grounding flat steel 9. 34. Horizontal grounding flat steel 10. 35. Multi-layer horizontal layered wind turbine location earth. 61. Horizontal measuring line. 62. Vertical measuring line. 63. The wind turbine generator set foundation grounding ring 1 is electrically connected to the wind turbine generator set horizontal grounding flat steel 1 3, wind turbine generator set horizontal grounding flat steel 2 4, and wind turbine generator set horizontal grounding flat steel 3 5 through grounding connection point 1 6, grounding connection point 2 7, and grounding connection point 3 8 respectively. The wind turbine generator set horizontal ring grounding device 2 is electrically connected to the vertical grounding electrode 1 12, vertical grounding electrode 2 13, vertical grounding electrode 3 14, and vertical grounding electrode 4 15 respectively. The wind turbine generator set horizontal grounding flat steel 1 3 and wind turbine generator set horizontal grounding flat steel 2 4 are electrically connected to the wind turbine generator set horizontal ring grounding device 2 through grounding connection point 4 9 and grounding connection point 5 10 respectively. The wind turbine generator set horizontal grounding flat steel 3 5 is electrically connected to the vertical grounding electrode 3 14. The grounding grid lead wire 11 is electrically connected to the wind turbine generator set horizontal ring grounding device 2 through grounding connection point 5 10. The horizontal grounding flat steel 416 and horizontal grounding flat steel 517 are electrically connected to the horizontal grounding flat steel 934 and horizontal grounding flat steel 1035 through grounding connection point 825 and grounding connection point 1027, respectively. The vertical grounding electrode 21 and the vertical grounding electrode 22 are electrically connected to the horizontal grounding device 29 of the box-type substation. The horizontal grounding device 29 of the box-type substation is electrically connected to the horizontal grounding flat steel 719 and the horizontal grounding flat steel 820 through grounding connection point six 23 and grounding connection point seven 24, respectively. The auxiliary grounding device 1 30 and auxiliary grounding device 3 32 are electrically connected to the horizontal grounding flat steel 7 19 and the horizontal grounding flat steel 8 20 respectively through grounding connection point 8 25 and grounding connection point 10 27. The auxiliary grounding device 2 31 and auxiliary grounding device 4 33 are electrically connected to the horizontal grounding flat steel 6 18 respectively through grounding connection point 9 26 and grounding connection point 11 28. The horizontal grounding flat steel 934 is electrically connected to the auxiliary grounding device 1 30 and the auxiliary grounding device 2 31 through grounding connection point 8 25 and grounding connection point 9 26 respectively, and the horizontal grounding flat steel 10 35 is electrically connected to the auxiliary grounding device 32 and the auxiliary grounding device 4 33 through grounding connection point 10 27 and grounding connection point 11 28 respectively. The second step involves conducting georesistivity tests at different locations and along different measuring lines using the Wenner four-electrode method: For a multi-layer horizontally stratified wind turbine site 61, soil resistivity tests were conducted under different electrode spans along horizontal survey line 62 and vertical survey line 63. During the test, the selected electrode spans under horizontal survey line 62 and vertical survey line 63 were kept equal. The electrical parameters under horizontal survey line 62 and vertical survey line 63 were estimated respectively. The obtained soil electrical parameters of each layer of the multi-layer horizontally stratified ground 61 were the arithmetic mean of the estimated results under horizontal survey line 62 and vertical survey line 63. Finally, the optimal grounding layer depth and the corresponding soil resistivity under the frozen soil layer were obtained.

[0012] The third step involves estimating the additional grounding electrode at different wind turbine locations. This includes deriving the grounding resistance formula for a composite grounding electrode with a closed main edge based on a horizontal grounding electrode in uniform soil, and performing data fitting calculations to determine the additional grounding electrode estimation factor. K F It can be obtained from the following formula: ; in, ; In the formula η The resistance reduction factor is the additional grounding electrode. L A This is expressed as the sum of the lengths of the horizontally grounded flat steel bars. S c This represents the total horizontal area of ​​the original composite grounding grid. H The optimal burial depth for laying horizontal grounding electrodes. ρ c This represents the soil resistivity of the soil layer where the horizontal grounding electrode is laid. L W It is represented as the sum of the lengths of the outer edges of the horizontal grounding grid.b The width of the horizontally grounded flat steel. D The thickness of the horizontal grounding flat steel. K T To evaluate the coefficient parameters, according to the electrical design specifications for wind farm projects, the grounding resistance required in the above formula is based on 4 ohms.

[0013] when K F When ∈(-∞,0], it indicates that the grounding resistance of the original composite grounding device meets the requirements, and no additional grounding electrode is needed; when K F When the value is (-∞, 0), it indicates that the grounding resistance of the original composite grounding device does not meet the requirements, and an additional grounding electrode is needed to reduce the grounding resistance. The estimation factor for the additional grounding electrode should be referenced. K F The expression can obtain the required amount of additional grounding electrode work.

Claims

1. A method for evaluating additional grounding devices in high resistivity wind farm areas considering horizontally layered geology, characterized in that, First, a grounding test platform for a high resistivity wind farm area considering layered geology is established. The platform includes: a wind turbine generator foundation grounding ring (1), a wind turbine generator horizontal ring grounding device (2), a wind turbine generator horizontal grounding flat steel bar one (3), a wind turbine generator horizontal grounding flat steel bar two (4), a wind turbine generator horizontal grounding flat steel bar three (5), a grounding connection point one (6), a grounding connection point two (7), a grounding connection point three (8), a grounding connection point four (9), a grounding connection point five (10), a grounding grid lead wire (11), a vertical grounding electrode one (12), a vertical grounding electrode two (13), a vertical grounding electrode three (14), a vertical grounding electrode four (15), a horizontal grounding flat steel bar four (16), and a horizontal grounding flat steel bar five (17). Horizontal grounding flat steel six (18), horizontal grounding flat steel seven (19), horizontal grounding flat steel eight (20), vertical grounding electrode five (21), vertical grounding electrode six (22), grounding connection point six (23), grounding connection point seven (24), grounding connection point eight (25), grounding connection point nine (26), grounding connection point ten (27), grounding connection point eleven (28), box-type substation horizontal grounding device (29), supplementary grounding device one (30), supplementary grounding device two (31), supplementary grounding device three (32), supplementary grounding device four (33), horizontal grounding flat steel nine (34), horizontal grounding flat steel ten (35), multi-layer horizontal layered wind turbine location earth (61), horizontal measuring line (62), vertical measuring line (63); The wind turbine generator base grounding ring (1) is electrically connected to the wind turbine generator horizontal grounding flat steel one (3), wind turbine generator horizontal grounding flat steel two (4), and wind turbine generator horizontal grounding flat steel three (5) through grounding connection point one (6), grounding connection point two (7), and grounding connection point three (8), respectively. The wind turbine generator horizontal ring grounding device (2) is electrically connected to the vertical grounding electrode one (12), vertical grounding electrode two (13), vertical grounding electrode three (14), and vertical grounding electrode four (15), respectively. The wind turbine generator horizontal grounding flat steel one (3) and wind turbine generator horizontal grounding flat steel two (4) are electrically connected to the wind turbine generator horizontal ring grounding device (2) through grounding connection point four (9) and grounding connection point five (10), respectively. The wind turbine generator horizontal grounding flat steel three (5) is electrically connected to the vertical grounding electrode three (14). The grounding grid lead wire (11) is electrically connected to the wind turbine generator horizontal ring grounding device (2) through grounding connection point five (10). Vertical grounding electrode four (15) is connected to horizontal grounding flat steel four (16), vertical grounding electrode three (14) is connected to horizontal grounding flat steel five (17), and the horizontal grounding flat steel four (16) and horizontal grounding flat steel five (17) are electrically connected to horizontal grounding flat steel nine (34) and horizontal grounding flat steel ten (35) respectively through grounding connection point eight (25) and grounding connection point ten (27); The vertical grounding electrode five (21) and vertical grounding electrode six (22) are electrically connected to the horizontal grounding device (29) of the box-type substation; The horizontal grounding device (29) of the box-type substation is electrically connected to the horizontal grounding flat steel seven (19) and the horizontal grounding flat steel eight (20) through grounding connection point six (23) and grounding connection point seven (24), respectively. The additional grounding device one (30) and the additional grounding device three (32) are electrically connected to the horizontal grounding flat steel seven (19) and the horizontal grounding flat steel eight (20) through grounding connection point eight (25) and grounding connection point ten (27), respectively. The additional grounding device two (31) and the additional grounding device four (33) are electrically connected to the horizontal grounding flat steel six (18) through grounding connection point nine (26) and grounding connection point eleven (28), respectively. The horizontal grounding flat steel nine (34) is electrically connected to the auxiliary grounding device one (30) and the auxiliary grounding device two (31) through grounding connection point eight (25) and grounding connection point nine (26), respectively. The horizontal grounding flat steel ten (35) is electrically connected to the auxiliary grounding device three (32) and the auxiliary grounding device four (33) through grounding connection point ten (27) and grounding connection point eleven (28), respectively. The second step involves conducting georesistivity tests at different locations and along different measuring lines using the Wenner four-electrode method: In the multi-layer horizontal stratified wind turbine site ground (61), soil resistivity tests were conducted with different electrode spans along the horizontal survey line (62) and the vertical survey line (63). During the test, the electrode spans selected under the horizontal survey line (62) and the vertical survey line (63) were kept equal. The electrical parameters under the horizontal survey line (62) and the vertical survey line (63) were estimated respectively. The obtained soil electrical parameters of each layer of the multi-layer horizontal stratified ground (61) were the arithmetic mean of the estimated results under the horizontal survey line (62) and the vertical survey line (63). Finally, the optimal grounding layer depth and the corresponding soil resistivity under the frozen soil layer were obtained. ρ c ; The third step is to estimate the additional grounding electrode at different wind turbine locations, and to determine the additional grounding electrode estimation factor. K F It can be obtained from the following formula: ； in, ; In the formula, η The resistance reduction factor is the additional grounding electrode. L A This is expressed as the sum of the lengths of the horizontally grounded flat steel bars. S c This represents the total horizontal area of ​​the original composite grounding grid. H The optimal burial depth for laying horizontal grounding electrodes. ρ c This represents the soil resistivity of the soil layer where the horizontal grounding electrode is laid. L W It is represented as the sum of the lengths of the outer edges of the horizontal grounding grid. b The width of the horizontally grounded flat steel. D The thickness of the horizontal grounding flat steel. K T These are the evaluation coefficient parameters; when K F When ∈(-∞,0], it indicates that the grounding resistance of the original composite grounding device meets the requirements, and no additional grounding electrode is needed; when K F When the value is (-∞, 0), it indicates that the grounding resistance of the original composite grounding device does not meet the requirements, and additional grounding electrodes are needed. The specific number of additional grounding electrodes can be referenced from the additional grounding electrode estimation factor. K F Numeric expression retrieval.

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