Construction method for reducing ground resistance of wind power generator

Abstract

This invention relates to the field of wind power generation technology, aiming to overcome the shortcomings of the prior art and provide a construction method for reducing the grounding resistance of wind turbines, comprising the following steps: Step S1: Conducting on-site geological surveys, establishing a construction plan, and preparing a conductive bonded suspension; Step S2: Establishing a multi-pole electric field system, an injection system, and a process monitoring system; Step S3: Injecting the conductive bonded suspension, applying an electric field, and constructing a three-dimensional conductive network; Step S4: Determining the completion of the three-dimensional conductive network construction by using the grounding resistance obtained from the process monitoring system, and dismantling the multi-pole electric field system, the injection system, and the process monitoring system. This invention constructs a chemically bonded, permanent three-dimensional conductive network in situ in the soil, achieving good and long-lasting resistance reduction in areas with high soil resistivity. Simultaneously, real-time monitoring of electrical parameters enables precise control of the construction process, improving the reliability of the project quality.

Description

Technical Field

[0001] This invention relates to the field of wind power generation technology, specifically a construction method for reducing the grounding resistance of wind turbine generators. Background Technology

[0002] As towering structures, wind turbines are highly susceptible to lightning strikes. Their safe and stable operation relies heavily on a low-resistance grounding system to quickly and safely discharge lightning currents and fault currents into the earth. Wind farms are typically located in open areas such as mountains and deserts, where the geological conditions are often dominated by sandy soil and rock with high soil resistivity, posing a significant challenge to obtaining the grounding resistance value required by regulations.

[0003] Currently, common techniques for reducing grounding resistance in areas with high soil resistivity include increasing the physical size of the grounding grid, replacing soil with low-resistivity soil, or using chemical resistance-reducing agents. However, simply increasing the amount of grounding electrodes or carrying out large-scale soil replacement work not only leads to a sharp increase in engineering costs and land occupation, but also has very limited effect on improving resistance reduction under extreme geological conditions.

[0004] As an alternative, chemical resistance-reducing agents are used in engineering. However, existing resistance-reducing agents generally suffer from short-lived effects. Most are water-soluble electrolytes, which migrate and are lost due to rainfall and groundwater, causing the grounding resistance to gradually deteriorate over time, requiring regular replenishment and incurring high maintenance costs. Furthermore, some components of resistance-reducing agents can corrode metallic grounding electrodes, damaging the integrity and safety of the grounding system with long-term use. Even when using more physically stable carbon-based conductive particles as backfill material, their resistance-reducing effect is limited by the contact resistance between particles, making it difficult to form a truly continuous conductive path on a macroscopic scale, thus restricting further performance improvements.

[0005] Therefore, there is an urgent need for a new construction method that can construct a long-term, stable, low-resistivity, and high-efficiency conductive path under geological conditions with high soil resistivity, and can overcome the shortcomings of traditional methods such as the short-lasting resistance reduction effect and the risk of corrosion. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings in the above-mentioned background technology and provide a construction method for reducing the grounding resistance of wind turbines, so as to solve the problems that the existing resistance reduction technology is not effective under geological conditions with high soil resistivity, the resistance reduction effect is unstable, and the construction process is difficult to control precisely.

[0007] The technical solution of this invention is: A construction method for reducing the grounding resistance of a wind turbine includes the following steps: Step S1: Preparation Phase Conduct on-site geological surveys, develop construction plans, and prepare conductive bonding suspensions; Step S2: Deployment Phase Establish a multi-polar electric field system, an injection system, and a process monitoring system; Step S3: Execution Phase Inject a conductive bonding suspension, apply an electric field, and construct a three-dimensional conductive network; Step S4: Termination Stage The completion of the three-dimensional conductive network construction was determined by the grounding resistance obtained from the process monitoring system, and the multi-pole electric field system, injection system, and process monitoring system were then dismantled.

[0008] The conductive bonded suspension comprises the following components: nano-conductive building blocks, electroactive monomers, polymeric polyanions, and an aqueous solvent. The nano-conductive building block is at least one of graphene, carbon nanotubes, and highly conductive carbon black; the electroactive monomer is 3,4-ethylenedioxythiophene; and the polymeric polyanion is polystyrene sulfonate. The mass percentage concentration of the nano-conductive building blocks is 0.1% to 5%; the mass percentage concentration of the electroactive monomers is 0.5% to 10%; the molar ratio of the polymeric polyanion to the electroactive monomers is 1:1 to 1:5; the remainder is an aqueous solvent.

[0009] The method for preparing the conductive bonded suspension includes: First, the surface-functionalized nano-conductive building blocks are placed in an aqueous solvent and treated with an ultrasonic dispersion device to form a uniform nano-conductive building block dispersion. Then, the electroactive monomers and polymeric polyanions are dissolved in the nano-conductive building block dispersion and all components are mixed uniformly by mechanical stirring to finally obtain a conductive bonded suspension.

[0010] The multi-pole electric field system includes a cathode, multiple anodes, and a DC power supply; the injection system includes a pressure pump, a flow meter, a container, and at least one injection pipeline; the process monitoring system includes a grounding resistance tester, an ammeter, and a voltmeter.

[0011] The applied electric field includes: The DC power supply operates in constant voltage mode, and by applying a constant voltage value, the average electric field strength formed in the main region between the cathode and anode is 0.5V / cm to 10V / cm. Alternatively, the applied electric field includes: the DC power supply 213 operating in a constant current mode, applying a constant current value such that an average current density of 0.1 mA / cm² is formed in the loop between the cathode and anode. 2 Up to 5mA / cm 2 .

[0012] The grounding resistance determination includes determining that when the total grounding resistance decreases to or below the target resistance value, the change in the total grounding resistance is less than a stable threshold within the monitoring period.

[0013] The monitoring duration is 1 to 4 hours; the stability threshold is 0.5% to 2% of the total grounding resistance.

[0014] The grounding resistance determination also includes: when the construction process adopts a constant voltage mode, the change in the total operating current value is less than the current stability threshold during the monitoring period; or, when the construction process adopts a constant current mode, the change in the total operating voltage value is less than the voltage stability threshold during the monitoring period.

[0015] The beneficial effects of this invention are: 1. This invention actively constructs a macroscopic three-dimensional conductive network formed by chemical bonding in soil pores through in-situ electrochemical polymerization reaction, rather than passively improving the conductivity of the soil. This method fundamentally changes the conductive structure around the grounding electrode, providing a macroscopic continuous low-resistivity discharge channel for lightning or fault current. Therefore, even in geological conditions with high soil resistivity where traditional resistance reduction methods are ineffective, it can still achieve excellent and reliable resistance reduction effects.

[0016] 2. This invention improves the stability and durability of the grounding resistance reduction effect. The three-dimensional conductive network is a solid-phase structure formed by chemically bonding nano-conductive units with conductive polymers. It is permanently anchored in the soil pore skeleton, exhibiting excellent chemical stability and insolubility in water. This characteristic fundamentally overcomes the problem of traditional chemical grounding resistance reducing agents failing due to groundwater seepage and leaching, ensuring highly stable performance of the grounding device throughout its entire design lifespan.

[0017] 3. This invention introduces a closed-loop control strategy that includes a termination phase. It utilizes a process monitoring system to acquire key electrical parameters such as total grounding resistance in real time and determines the construction endpoint based on explicit numerical values ​​and stability trend criteria. This method transforms the construction process of the resistance-reducing structure from an experience-based, opaque operation into a data-driven, standardized engineering process, improving the reliability and consistency of construction quality. Attached Figure Description

[0018] The following describes some specific embodiments of the invention in a detailed manner by way of example and not limitation, with reference to the accompanying drawings. The same reference numerals in the drawings denote the same or similar parts or portions.

[0019] Figure 1 This is a flowchart illustrating the construction method of the present invention.

[0020] Figure 2This is a schematic diagram of the connection relationship of the construction system of the present invention.

[0021] Reference numerals: 200, construction system; 210, multi-pole electric field system; 211, cathode; 212, anode; 213, DC power supply; 220, injection system; 230, process monitoring system. Detailed Implementation

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] I. Construction Method See attached document Figure 1 This invention provides a construction method for reducing the grounding resistance of wind turbine generators, comprising the following steps: Step S1: Preparation Phase This phase includes on-site geological surveys, development of construction plans, and preparation of conductive bonding suspensions.

[0024] On-site geological survey: Conduct geological parameter surveys of the construction area and obtain soil resistivity. Spatial distribution data. The spatial distribution data includes vertically layered resistivity and horizontal resistivity distribution; this data is used to identify high resistivity areas as key areas for resistivity reduction, and combined with the design drawings of the wind turbine grounding grid, the critical path for current discharge is determined.

[0025] Establish a construction plan based on soil resistivity. Spatial distribution data was used to confirm multiple anode, cathode, and injection locations for construction. Specifically, based on the cathode location as the center, and according to soil resistivity... To determine the optimal location, select areas with higher soil resistivity within a radius of 3 to 20 meters from the cathode as anode placement points; set the injection location on the line connecting the cathode and anode, and ensure the injection hole depth covers the burial depth range of the main grounding electrode (e.g., 0.8 to 3 meters underground). In high-resistivity regions, appropriately increase the density of anodes and injection points.

[0026] Preparation of conductive bonded suspension: The conductive bonded suspension contains surface-functionalized nano-conductive units, electroactive monomers, polymeric polyanions, and aqueous solvents.

[0027] The anode (auxiliary electrode), injection system, and process monitoring system are temporary equipment and need to be dismantled sequentially during the site restoration phase after construction.

[0028] Step S2: Deployment Phase This phase includes the on-site deployment of construction systems.

[0029] According to the construction plan, a multi-pole electric field system, an injection system, and a process monitoring system will be established.

[0030] A multi-pole electric field system includes an anode, a cathode, and a DC power supply. An anode (auxiliary electrode) is installed at the anode position, and a cathode (main grounding electrode) is installed at the cathode position. The anode is connected to the negative terminal of the DC power supply, and multiple cathodes are connected to the positive terminal of the DC power supply, thus forming a complete multi-pole electric field system.

[0031] The injection system is used to inject conductive bonded suspensions.

[0032] The process monitoring system is used to monitor electrical parameters during the construction process.

[0033] The anode (auxiliary electrode), injection system, and process monitoring system are among the deployed equipment that need to be removed sequentially.

[0034] Step S3: Execution Phase This stage is the in-situ construction process of the three-dimensional conductive network, which is the core execution step of this method.

[0035] Step S3.1: Inject conductive bonding suspension The conductive bonded suspension is injected into the underground area at a preset injection location using an injection system.

[0036] Step S3.2: Apply an electric field and construct a three-dimensional conductive network Turn on the DC power supply and apply a preset electric field between the anode (auxiliary electrode) and the cathode (main grounding electrode). In one embodiment, the electric field strength The value ranges from 0.5V / cm to 5V / cm. In the electric field... Under the influence of [the specific mechanism / effect], charged components in the conductive bonded suspension undergo directional migration within the soil pores. The migration rate of the charged components [is described]. Electrophoresis speed With electroosmotic flow rate They jointly decided that their relationship is as follows: ; Among them, electrophoresis speed The calculation formula is: ; in, denoted as , representing the electrophoretic mobility of the charged component.

[0037] Electroosmotic flow rate The calculation formula is: ; in, This represents the electroosmotic mobility.

[0038] During directional migration, nano-conductive building blocks form localized enrichment zones within soil pores. The formation of these localized enrichment zones leads to a localized current density within those regions. Increase. When the local current density This causes the anodic overpotential on the surface of the nano-conductive building block. When the polymerization threshold of the electroactive monomer is reached or exceeded, the electroactive monomer undergoes in-situ electrochemical polymerization on the surface of the nano-conductive building blocks, generating a conductive polymer. The conductive polymer chemically bonds adjacent nano-conductive building blocks, thereby forming a three-dimensional conductive network within the soil that is electrically connected to the main grounding electrode.

[0039] Anode overpotential The definition of is: ; in, This represents the anodic potential on the surface of the nano-conductive building block. This represents the equilibrium oxidation potential of the electroactive monomer.

[0040] Step S4: Termination Stage This phase includes process monitoring, endpoint determination, and site restoration.

[0041] Step S4.1: Process Monitoring During the applied electric field in step S3, the real-time data of the total grounding resistance is continuously acquired through the process monitoring system. Step S4.2: Endpoint determination When the total grounding resistance drops to the preset target value and remains stable within the subsequent preset monitoring period, it is determined that the three-dimensional conductive network has been successfully constructed.

[0042] Step S4.3: Site Restoration After the three-dimensional conductive network is constructed, the DC power supply is cut off, the temporarily deployed equipment is dismantled, and the construction site is restored. The dismantling of the temporarily deployed equipment includes the sequential removal of the anode (auxiliary electrode), the injection system, and the process monitoring system.

[0043] II. Conductive Bonded Suspension See attached document Figure 2 The construction method in this embodiment of the invention relies on a conductive bonded suspension.

[0044] Conductive bonded suspension is a multi-component water-based dispersion system, whose components include: nano-conductive units, electroactive monomers, high molecular weight polyanions, and aqueous solvents.

[0045] Nanoscale conductive elements form the basic conductive framework for constructing three-dimensional conductive networks. In one embodiment, the nanoscale conductive elements are selected from at least one of graphene, carbon nanotubes, and highly conductive carbon black. To ensure their long-term dispersion stability in aqueous solvents and their directional migration ability under an electric field, the surface of the nanoscale conductive elements undergoes chemical functionalization treatment. Specifically, functional groups containing carboxyl or sulfonic acid groups are grafted onto the surface of the nanoscale conductive elements through chemical oxidation. These functional groups dissociate in aqueous solution, giving the surface of the nanoscale conductive elements a stable negative charge, thereby generating electrostatic repulsion between particles and preventing their aggregation; simultaneously, this negative charge is the physical basis for their electrophoretic migration in an electric field.

[0046] Electroactive monomers are key reactants that undergo in-situ electrochemical polymerization on the surface of nano-conductive building blocks to form chemical bonds. In one embodiment, the electroactive monomer is 3,4-ethylenedioxythiophene. Electroactive monomers exhibit good electrochemical activity in aqueous environments, and the polymer formed from 3,4-ethylenedioxythiophene exhibits high conductivity and excellent chemical stability.

[0047] Polymeric polyanions possess a dual function in conductive bonded suspensions. First, as a stabilizer, their long-chain structure can physically coat or adsorb onto the surface of conductive nanofibers, providing steric hindrance and further enhancing the dispersion stability of the conductive nanofibers. Second, as a dopant, during the polymerization of electroactive monomers to form positively charged conductive polymer chains, polymeric polyanions can act as dopant anions to balance the charge, embedding themselves into the polymer network, thereby ensuring that the final conductive polymer exhibits high conductivity.

[0048] In one embodiment, the polymeric polyanion is polystyrene sulfonate.

[0049] In a preferred embodiment, the mass percentage concentration range of each component in the conductive bonded suspension is as follows: 0.1% to 5% of the mass percentage concentration of the nano-conductive building blocks; 0.5% to 10% of the mass percentage concentration of the electroactive monomers; a molar ratio of polymeric polyanion to electroactive monomers of 1:1 to 1:5; and the remainder being an aqueous solvent. This concentration range ensures that the conductive bonded suspension has good flowability and dispersion stability while also providing sufficient reactants to form an effective conductive network.

[0050] To illustrate the proportions in detail, the following three specific examples are provided: Example 1 (Low Concentration): 0.1% nano-conductive building blocks (functionalized graphene), 0.5% electroactive monomer (EDOT), 1:1 molar ratio of polymeric polyanionic polymer (PSS) to monomer, and the remainder is deionized water. Suitable for dense soils with low porosity and poor permeability.

[0051] Example 2 (medium concentration): 2.5% conductive nanotubes, 5% electroactive monomer (EDOT), 1:3 molar ratio of polyanionic polymer (PSS) to monomer, and the remainder is deionized water. Suitable for conventional sandy soils.

[0052] Example 3 (High Concentration Type): 5% nano-conductive building blocks (highly conductive carbon black), 10% electroactive monomer (EDOT), 1:5 molar ratio of polymeric polyanionic (PSS) to monomer, and the remainder is deionized water. Suitable for loose gravelly soil environments with high porosity and an urgent need for rapid drag reduction.

[0053] Methods for preparing conductive bonded suspensions include: First, the surface-functionalized conductive nano-units are placed in an aqueous solvent and treated with an ultrasonic dispersion device. The ultrasonic power is 500W to 1500W, the ultrasonic frequency is 20kHz to 40kHz, and the treatment time is 30 to 60 minutes to form a uniform dispersion of conductive nano-units. Then, the electroactive monomer and the polymeric polyanion are dissolved in the nano-conductive unit dispersion, and all components are mixed evenly by mechanical stirring at a speed of 500 to 1000 rpm for 60 to 120 minutes to finally obtain a conductive bonded suspension.

[0054] III. Construction System See attached document Figure 2 The construction method in this embodiment of the invention depends on the construction system 200.

[0055] The construction system 200 includes a multi-pole electric field system 210, an injection system 220, and a process monitoring system 230.

[0056] 1. Multipole electric field system The multi-pole electric field system 210 is used to establish a controlled DC electric field in an underground target area, serving as the power source for driving the directional migration of conductive bonded suspensions. The multi-pole electric field system 210 includes a cathode 211, multiple anodes 212, and a DC power supply 213.

[0057] The cathode 211 can be an existing main grounding electrode of the wind turbine or a reserved test terminal. The anode 212 is a temporarily installed auxiliary electrode, and its material is selected from chemically stable and highly conductive inert materials, such as graphite electrodes or titanium electrodes coated with noble metal oxides, to prevent it from being lost or generating secondary pollution during electrochemical reactions. Multiple anodes 212 are buried in the peripheral area of ​​the cathode 211 according to a preset geometric configuration.

[0058] The preferred geometric configuration is a ring-shaped radial distribution, where multiple anodes are evenly distributed on a circle with radius R centered at the geometric center of the cathode. The radius R is 1.5 to 3 times the maximum diagonal length of the cathode (main grounding electrode). This configuration ensures that the electric field covers the main current discharge area around the grounding electrode.

[0059] The DC power supply 213 is a programmable power supply that can provide a constant voltage or constant current output mode. Its positive terminal is electrically connected to multiple anodes 212, and its negative terminal is electrically connected to the cathode 211.

[0060] 2. Injection System The injection system 220 is used to deliver a conductive bonded suspension to a predetermined underground location. The injection system 220 includes a pressure pump, a flow meter, a container, and at least one injection line. The container stores the conductive bonded suspension. One end of the injection line is connected to the container, and the other end is equipped with a permeator that extends into the soil at the injection location. The depth of the permeator is preferably 1.5 meters to 3 meters, and the spacing between adjacent injection points is 2 meters to 5 meters to facilitate uniform distribution of the suspension in the soil. The pressure pump and flow meter are located on the injection line.

[0061] 3. Process monitoring system The process monitoring system 230 is used to acquire key electrical parameters in real time during the construction process, providing data for process control and endpoint determination.

[0062] Process monitoring system 230 includes: A grounding resistance tester is used to measure the total grounding resistance (i.e., power frequency grounding resistance) of the main grounding electrode. An ammeter, connected in series in the output circuit of DC power supply 213, is used to measure the total operating current; A voltmeter, connected in parallel to the output terminal of DC power supply 213, is used to measure the total operating voltage.

[0063] IV. Constructing a three-dimensional conductive network The method for constructing a three-dimensional conductive network for a construction system includes the following steps: 1. Injecting conductive bonding suspension The prepared conductive bonded suspension is injected into a predetermined target area underground via the injection system 220 in the construction system 200. This injection process is carried out under controlled low-pressure conditions, specifically between 0.1 MPa and 0.4 MPa, to ensure that the conductive bonded suspension enters the soil pore structure uniformly through permeation, rather than causing hydraulic fracturing damage to the soil structure due to high pressure. A flow meter in the injection system 220 is used to monitor and control the injection rate, which is controlled between 5 L / min and 20 L / min, to achieve the total injection volume pre-calculated based on the geometric volume and soil porosity of the target area.

[0064] Total injection volume The calculation formula is: ;in The volume of the soil to be improved (the volume of a cylinder with the injection point as the center and a diffusion radius of R). Soil porosity, The target saturation coefficient (values ​​range from 0.4 to 0.8).

[0065] 2. Applying an electric field Upon completion of the injection process or in the final stage of the injection process, the DC power supply 213 in the multi-pole electric field system 210 is activated to apply the electric field. The initialization operation of the electric field application has at least two selectable control modes.

[0066] In one embodiment, the DC power supply 213 operates in a constant voltage mode. In this mode, a preset constant voltage value is used. It is applied between the cathode 211 and multiple anodes 212. The value is set within a specific range. The lower limit of this range must be sufficient to generate an electric field strength that effectively drives the migration of charged components in the soil, while the upper limit is lower than the theoretical decomposition voltage of water in the current soil environment, in order to avoid energy loss and disturbance to the soil pore structure caused by the generation of a large amount of gas due to the electrolysis of water.

[0067] Specifically, constant voltage value The choice of [electrode name] should ensure that the average electric field strength formed in the main region between the cathode and anode is [value]. The voltage should be between 0.5V / cm and 10V / cm. Below 0.5V / cm, the electrophoresis and electroosmosis effects are weak, and the construction period is too long; above 10V / cm, energy consumption increases significantly, and the risk of water electrolysis side reactions increases.

[0068] In another embodiment, the DC power supply 213 operates in a constant current mode. In this mode, a preset constant current value is used. The current is maintained within a circuit consisting of cathode 211 and multiple anodes 212. This constant current mode provides a constant charge transport rate, thus offering a more stable driving force for subsequent electrophoretic migration and electrochemical reactions. (Constant current value) The value is determined based on the total surface area of ​​the electrodes and the initial current density required to achieve effective migration.

[0069] The calculation formula is: .in, To optimize the current density, the value is set within the range of 0.1 mA / cm². 2 Up to 5mA / cm 2 ; It is the effective surface area of ​​the cathode (main grounding electrode) in contact with the soil.

[0070] After the electric field is applied and stabilized, the charged components in the conductive bonded suspension, mainly negatively charged nano-conductive units with surface functionalization, begin to migrate in a direction under the drive of the composite field present in the soil pores and eventually accumulate in specific areas.

[0071] The following explains the composite field drive.

[0072] The combined field drive includes electrophoresis and electroosmosis effects.

[0073] Electrophoresis refers to the phenomenon where negatively charged nano-conductive elements in an electric field exhibit electrophoretic properties. Under the influence of an electric field pointing towards the anode, it is electrophoretic at a specific velocity. Migration occurs. Electrophoresis speed. It can be determined by the following formula: ; in, denoted as , representing the electrophoretic mobility of the nano-conductive building blocks.

[0074] Electrophoretic mobility of nano-conductive building blocks Zeta potential on the surface of nano-conductive building blocks Dielectric constant of liquid phase medium in soil pores and the dynamic viscosity of the liquid medium The correlation can be described by the Helmholtz-Smoluchowski equation: ; The electroosmotic effect refers to the phenomenon where, because most soil particles naturally carry a negative charge on their surface, they adsorb cations from the pore water solution, forming an electrical double layer. Under an electric field... Under the influence of [the cathode], cations, along with their hydrated layers, move towards the cathode, forming electroosmotic flow. Electroosmotic flow velocity [is as follows]. It can be determined by the following formula: ; in, This represents the electroosmotic mobility.

[0075] Therefore, the final migration of the nano-conductive building blocks is the result of the combined effects of electrophoresis and electroosmosis. Its net migration rate... It is the speed of electrophoresis. and electroosmotic flow rate The vector sum. In embodiments of the invention, a sufficiently high Zeta potential is obtained by surface functionalizing the nano-conductive building blocks. This ensures its electrophoresis speed. Numerically significantly greater than the electroosmotic flow rate This enables the overall net directional migration of the nano-conductive building blocks toward the anode.

[0076] During directional migration, the enrichment of nano-conductive building blocks is achieved through at least two of the following mechanisms: Firstly, there is the physical sieving effect. Soil is a heterogeneous porous medium with unevenly distributed pore channel sizes. When a nano-conductive element migrates to a pore throat smaller than its effective hydration diameter, its migration is hindered or trapped, leading to accumulation and enrichment at that location.

[0077] Secondly, the electromigration focusing effect. Electric field Electric field lines are not uniformly distributed within the microscopic structure of soil pores. At the narrow pore channels between soil particles, electric field lines converge, leading to localized variations in electric field strength. The electric field strength is higher than the average. According to the electrophoretic velocity formula, the nano-conductive building blocks are accelerated when entering this high-field region, and decelerated when leaving this high-field region and entering wider pores with lower field strength. This velocity difference causes the nano-conductive building blocks to aggregate in these regions where the pore structure changes, especially at the exit where the pores widen, forming enrichment regions.

[0078] The directional migration and enrichment of nano-conductive building blocks create the necessary local conditions for subsequent electrochemical bonding reactions. The electrochemical bonding mechanism is an in-situ chemical reaction process passively triggered when local electrical parameters exceed a specific threshold.

[0079] First, in the enriched region formed by the nano-conductive building blocks, a low-resistance channel preferentially allows current to flow because the conductivity of the nano-conductive building blocks is much higher than that of the surrounding soil liquid phase medium. This effect leads to a higher local current density flowing through this enriched region. The current density is higher than that of the surrounding non-rich areas.

[0080] Secondly, the electrochemical bonding reaction is an electrode reaction that occurs on the surface of the nano-conductive building block; therefore, each nano-conductive building block acts as a microelectrode in this process. The occurrence and rate of the electrochemical reaction are directly determined by the anodic overpotential on the surface of the microelectrode. Determined by. Anode overpotential Defined as the actual anodic potential on the surface of a nano-conductive building block. Equilibrium oxidation potential of electroactive monomers under this environment Difference: ; Under the globally applied voltage, the anodic overpotential in most areas is... All values ​​are below those required to initiate a polymerization reaction. However, in the enrichment region, the self-reinforcing local current density... This leads to the actual anodic potential on the surface of the nano-conductive building block. The corresponding increase leads to an anodic overpotential in that region. It increases accordingly.

[0081] When the anode overpotential When the current density increases to a critical threshold, the electrochemical polymerization reaction is triggered. The kinetics of this process follow the Tafel equation, i.e., the local current density... Anode overpotential It exhibits an exponential relationship: ; in: For exchange current density; The anodic charge transfer coefficient; The number of electrons transferred per step in the polymerization reaction; It is Faraday's constant; It is the ideal gas constant; It is the thermodynamic temperature.

[0082] The exponential relationship indicates that once the anode overpotential... Beyond this critical threshold, the reaction rate (by...) The nonlinear growth of the material will occur. At this time, electroactive monomers (such as 3,4-ethylenedioxythiophene) undergo a large-scale oxidative polymerization reaction on the surface of the nano-conductive unit, generating conductive polymers (such as polymers of 3,4-ethylenedioxythiophene).

[0083] Finally, the newly generated conductive polymer acts as a conductive solid-phase binder, chemically bonding the previously loosely connected or physically adjacent nano-conductive units in situ. This process transforms the point or surface contacts between particles into a continuous, integrated composite material structure, forming a mechanically stable and electrically highly interconnected conductive network of nodes.

[0084] The triggering of electrochemical bonding in local regions is the starting point for the formation of conductive networks. This process then enters a self-optimizing growth and solidification stage, ultimately forming a macroscopic, continuous conductive pathway.

[0085] The self-optimizing growth process is based on a positive feedback mechanism. Once an initial conductive network node is formed through electrochemical bonding, the equivalent resistivity of the node is lower than that of the surrounding unbonded regions. According to charge conservation and Ohm's law, the total current flowing through this region will preferentially select to flow through this low-resistivity bonded node.

[0086] This redistribution of current leads to an increase in the current flowing through the bonded node, which in turn increases the local current density in its downstream or adjacent regions. Further increases. Increased local current density. This causes anodic overpotential in these adjacent areas. As it increases, once the threshold of the polymerization reaction is reached, a new electrochemical bonding reaction will be triggered, allowing the conductive network nodes to expand in size or extend outward.

[0087] This process repeats continuously: the expansion of the bonded region further reduces the resistance of the path, thereby attracting more current and accelerating the bonding reaction at its front end. This positive feedback mechanism ensures that the growth of the conductive network preferentially proceeds along the path with the highest electric field strength and optimal initial conductivity conditions. Ultimately, starting from microscopic, discrete bonding points, they grow and connect into macroscopic, continuous filamentary or mesh-like conductive structures, which spatially constitute the optimal discharge channels connecting the main grounding electrode to the depths of the soil.

[0088] The solidification process occurs simultaneously with the growth process. The electrochemical polymerization reaction is an irreversible process that transforms electroactive monomers in the liquid phase into a solid, water-insoluble conductive polymer. As the conductive network continues to grow, the electroactive monomers in the conductive bonded suspension are continuously consumed. When the construction process ends, the formed conductive polymer network, as a permanent solid structure, is solidified and anchored in the porous matrix of the soil, thus completing the transformation from a dynamic construction process to a static, functionally stable three-dimensional conductive network.

[0089] V. Process Monitoring During the construction process of this embodiment of the invention, at least three key process parameters are monitored in real time by the process monitoring system 230 in the construction system 200 to obtain dynamic information on the in-situ construction process of the three-dimensional conductive network. The key process parameters include: total grounding resistance, total operating current, and total operating voltage.

[0090] It is important to clearly distinguish that the total grounding resistance refers to the resistance value of the wind turbine's main grounding electrode relative to the distant earth, and is the ultimate indicator for measuring the resistance reduction effect; while the loop impedance calculated from the total operating voltage and total operating current (…) The total impedance of an electrochemical circuit, including the anode, cathode, and the soil medium between them, is a process indicator reflecting the growth of conductive channels during construction.

[0091] Total grounding resistance is the final physical quantity that directly characterizes the resistance reduction effect of this construction method. Periodic or continuous measurements using a grounding resistance tester can yield a curve showing the total grounding resistance changing over time. The physical significance of this curve lies in the fact that its numerical change directly reflects the formation and evolution of the three-dimensional conductive network. In the initial stage of construction, due to the existence of only the intrinsic conductive pathways of the soil, the grounding resistance value is at a relatively high level. As nano-conductive elements migrate and accumulate under the influence of the electric field, and undergo electrochemical bonding reactions along the dominant pathways, discrete conductive nodes are connected into continuous conductive pathways. These newly formed pathways provide parallel, low-impedance discharge paths for the grounding resistance test current, resulting in a continuous decrease in the measured total grounding resistance value.

[0092] Total operating current and total operating voltage are electrical parameters that characterize the state of the entire underground electrochemical system. They are related through the system loop impedance, and their dynamic changes together reflect the progress of the construction of the underground three-dimensional conductive network.

[0093] In one embodiment, when the DC power supply 213 operates in constant voltage mode, the monitored trend of the total operating current reflects the change in the system loop impedance. As the three-dimensional conductive network forms and grows, the loop impedance of the underground system decreases. According to Ohm's law, under the condition of a constant voltage applied across the electrodes, the value of the total operating current will show a continuous upward trend. The rate of this current increase reflects, to some extent, the growth rate of the three-dimensional conductive network.

[0094] In another embodiment, when the DC power supply 213 operates in constant current mode, the monitored trend of the total operating voltage reflects the change in the system loop impedance. As the three-dimensional conductive network forms and grows, the loop impedance of the underground system decreases. To maintain a constant total operating current in the loop, the output voltage required by the DC power supply 213 will decrease accordingly. Therefore, in constant current mode, the value of the total operating voltage will show a continuously decreasing trend. The rate of this voltage decrease also reflects, to some extent, the growth rate of the three-dimensional conductive network.

[0095] In a complete construction process, the curve of total grounding resistance changing over time typically exhibits three stages: The stable phase corresponds to the initial stage of construction, where the electric field is established but the three-dimensional conductive network has not yet been formed in large quantities, and the total grounding resistance is at a high level and changes slowly. During the rapid descent phase, the three-dimensional conductive network begins to undergo large-scale bonding and growth along the dominant path, resulting in a decrease in total grounding resistance. The gradual stabilization stage corresponds to the end of the construction period, when the main three-dimensional conductive network has been formed and solidified, and the total grounding resistance tends to a stable low value.

[0096] Identifying these characteristic stages is the foundation for process control and endpoint determination.

[0097] In this embodiment of the invention, the determination of the construction endpoint is based on the analysis of real-time data of key process monitoring parameters to ensure that the three-dimensional conductive network has reached the expected functional state and has been solidified. The criteria for determining the construction endpoint include a primary criterion and an auxiliary criterion.

[0098] The main criterion is based on the total grounding resistance value and its rate of change over time. The completion of the construction project requires the simultaneous fulfillment of the following two conditions: Numerical conditions: The measured total grounding resistance has been reduced to or below a target resistance value pre-set according to design specifications or geological conditions. For example, for wind turbine generators, this target resistance value is usually set to below 4 ohms (specifically according to relevant standards such as GB / T 35694).

[0099] Stability condition: After meeting the numerical conditions, the change in the total grounding resistance is less than a preset stability threshold within a continuous, preset monitoring period. This stability condition indicates that the growth process of the conductive network has been basically completed, and its macroscopic conductivity has entered a stable state.

[0100] In a specific embodiment, the selection of the preset monitoring duration and the preset stability threshold needs to strike a balance between ensuring the reliability of the construction endpoint determination and the economic efficiency of construction.

[0101] The preset monitoring duration is typically set to 1 to 4 hours. If the duration is too short, it will be impossible to effectively identify potential instability in the system; if the duration is too long, it will unnecessarily extend the total construction period and increase costs.

[0102] The preset stability threshold is typically set to 0.5% to 2% of the total grounding resistance. If the threshold is too small, the endpoint may be difficult to determine due to instrument measurement noise or slight environmental fluctuations; if the threshold is too large, construction may be terminated prematurely before the three-dimensional conductive network has fully solidified and stabilized.

[0103] In a preferred embodiment, this combination has been proven in extensive practice to reliably confirm that the three-dimensional conductive network has reached a stable state.

[0104] The auxiliary criterion is based on the time rate of change of the total operating current or the total operating voltage, which is used to confirm from the perspective of the system's electrochemical state that the construction process of the conductive network has reached saturation or equilibrium.

[0105] In one embodiment, when the construction process adopts a constant voltage mode, the auxiliary criterion is: within the monitoring time corresponding to the stability condition of the main criterion, the change in the monitored total operating current value is less than a preset current stability threshold, which is preferably 1% to 5% of the current total operating current value. This phenomenon indicates that the loop impedance of the underground system is no longer significantly reduced, thus confirming that the growth of the conductive network has tended to stop.

[0106] In another embodiment, when the construction process adopts a constant current mode, the auxiliary criterion is: within the monitoring time corresponding to the stability condition of the main criterion, the change in the monitored total operating voltage value is less than a preset voltage stability threshold, which is preferably 1% to 5% of the current total operating voltage value. This phenomenon also indicates that the loop impedance of the underground system is no longer significantly reduced.

[0107] The final termination order for construction is issued when both the primary and secondary criteria are met. This dual criterion ensures the accuracy and reliability of the construction endpoint determination.

[0108] In one alternative embodiment, the components of the conductive bonded suspension can be replaced with other materials having the same or similar functions. For example, in addition to graphene or carbon nanotubes, the nanoconductive building blocks can be conductive metal nanoparticles, such as silver nanowires or surface-passivated copper nanoparticles, whose surfaces are also chemically functionalized to carry stable surface charges. As another example, the electroactive monomer can be other monomers capable of anodic polymerization in an aqueous environment, such as pyrrole, aniline, or their derivatives, besides 3,4-ethylenedioxythiophene. Correspondingly, the polymeric polyanion can be other water-soluble polyelectrolytes that can act as stabilizers and dopants, such as polyacrylic acid or chemically modified natural polymers, besides polystyrene sulfonate.

[0109] In one alternative implementation, the electric field loading mode can be a non-constant mode. For example, a DC power supply can apply a pulsed electric field. The pulsed electric field consists of a series of voltage or current pulses with preset duty cycles, frequencies, and amplitudes. By allowing the ion concentration gradient to relax during the pulse rest intervals, this mode can modulate the migration processes and electrochemical reaction processes of the nano-conductive building blocks.

[0110] In one alternative implementation, the layout of the multi-electrode electric field system in the construction system can have other geometric configurations. For example, multiple anodes can be buried at different depths to form a three-dimensional electrode array, which can regulate the electric field distribution in the vertical direction, thereby guiding the conductive network to grow to a specific soil depth.

[0111] In another alternative implementation, the functions of the injection system and the anode can be integrated into the same device. For example, a porous hollow tubular inert electrode can be used as the anode, while the conductive bonded suspension is injected through the internal cavity of the electrode and permeates into the surrounding soil through micropores in its tube wall. This structure precisely combines the injection point of the suspension with the anode location.

[0112] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A construction method for reducing the grounding resistance of a wind turbine generator, comprising the following steps: Step S1: Preparation Phase Conduct on-site geological surveys, develop construction plans, and prepare conductive bonding suspensions; Step S2: Deployment Phase Establish a multi-polar electric field system, an injection system, and a process monitoring system; Step S3: Execution Phase Inject a conductive bonding suspension, apply an electric field, and construct a three-dimensional conductive network; Step S4: Termination Stage The completion of the three-dimensional conductive network construction was determined by the grounding resistance obtained from the process monitoring system, and the multi-pole electric field system, injection system, and process monitoring system were then dismantled.

2. The construction method for reducing the grounding resistance of wind turbine generators according to claim 1, characterized in that: The conductive bonded suspension comprises the following components: nano-conductive building blocks, electroactive monomers, polymeric polyanions, and an aqueous solvent. The nano-conductive building block is at least one of graphene, carbon nanotubes, and highly conductive carbon black; the electroactive monomer is 3,4-ethylenedioxythiophene; and the polymeric polyanion is polystyrene sulfonate. The mass percentage concentration of the nano-conductive building blocks is 0.1% to 5%; the mass percentage concentration of the electroactive monomers is 0.5% to 10%; the molar ratio of the polymeric polyanion to the electroactive monomers is 1:1 to 1:5; the remainder is an aqueous solvent.

3. The construction method for reducing the grounding resistance of wind turbines according to claim 2, characterized in that: The method for preparing the conductive bonded suspension includes: First, the surface-functionalized nano-conductive building blocks are placed in an aqueous solvent and treated with an ultrasonic dispersion device to form a uniform nano-conductive building block dispersion. Then, the electroactive monomers and polymeric polyanions are dissolved in the nano-conductive building block dispersion and all components are mixed uniformly by mechanical stirring to finally obtain a conductive bonded suspension.

4. The construction method for reducing the grounding resistance of a wind turbine generator according to claim 3, characterized in that: The multi-pole electric field system includes a cathode, multiple anodes, and a DC power supply; the injection system includes a pressure pump, a flow meter, a container, and at least one injection line. The process monitoring system includes: a grounding resistance tester, an ammeter, and a voltmeter.

5. The construction method for reducing the grounding resistance of a wind turbine generator according to claim 4, characterized in that: The applied electric field includes: The DC power supply operates in constant voltage mode, and by applying a constant voltage value, the average electric field strength formed in the main region between the cathode and anode is 0.5V / cm to 10V / cm. Alternatively, the applied electric field includes: the DC power supply 213 operating in a constant current mode, applying a constant current value such that an average current density of 0.1 mA / cm² is formed in the loop between the cathode and anode. 2 Up to 5mA / cm 2 .

6. The construction method for reducing the grounding resistance of a wind turbine generator according to claim 5, characterized in that: The grounding resistance determination includes determining that when the total grounding resistance decreases to or below the target resistance value, the change in the total grounding resistance is less than a stable threshold within the monitoring period.

7. The construction method for reducing the grounding resistance of a wind turbine generator according to claim 6, characterized in that: The monitoring duration is 1 to 4 hours; the stability threshold is 0.5% to 2% of the total grounding resistance.

8. The construction method for reducing the grounding resistance of a wind turbine generator according to claim 7, characterized in that: The grounding resistance determination also includes: when the construction process adopts a constant voltage mode, the change in the total operating current value is less than the current stability threshold during the monitoring period; or, when the construction process adopts a constant current mode, the change in the total operating voltage value is less than the voltage stability threshold during the monitoring period.

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