High-voltage cable intermediate joint hydrogen evolution corrosion experiment device and method

Abstract

The invention belongs to the technical field of electric power research, and discloses a high-voltage cable intermediate joint hydrogen evolution corrosion experiment device and method.The experiment device comprises a hydrogen production test platform used for testing a metal sheet and an EVA sheet of a metal / EVA structure in a simulated cable joint under different current density conditions and testing generated hydrogen; and the electrochemical test platform is used for carrying out electrochemical test on the metal sheet with the metal / EVA structure in the simulated cable joint before and after hydrogen production. According to the method, the action analysis of free radicals in the metal and EVA hydrogen evolution corrosion process in the intermediate joint of the high-voltage cable can be realized, effective data support is provided for the corrosion behavior and mechanism analysis of the intermediate joint of the high-voltage cable, and the hydrogen evolution corrosion process of the metal and EVA under the action of different free radical quenching agents and free radical trapping agents can be analyzed. The method has very important significance on corrosion of materials and targeted selection, design and application of corrosion inhibitors.

Description

Technical Field

[0001] The present invention belongs to the technical field of power research, relates to the corrosion research of high-voltage cable joints, and particularly relates to an experimental device and method for hydrogen evolution corrosion of high-voltage cable joints. Background Art

[0002] In recent years, cable accidents caused by cable joints have occurred frequently, posing a great threat to the safety of the power transmission system. The internal structure of high-voltage cable joints is complex and the operating environment is harsh. A large number of metal components are provided at the joints to provide a circulating current discharge channel and waterproof protection for the cable. High-voltage cable joints usually consist of metal cable cores, connecting pipes, grading sleeves, silicone rubber prefabricated parts, copper shells and other components, and contain metal materials such as aluminum (Al) and copper (Cu), and organic materials such as cross-linked polyethylene and ethylene-vinyl acetate copolymer (EVA). When the joints operate under different working conditions, the leakage current flowing through the joints is different. Coupled with the possible failure of the joint sealing material leading to the intrusion of moisture, it is very likely that different electrodes are formed between the metal materials and organic materials in the joint, which may cause the risk of hydrogen evolution corrosion of the cable joint, and even lead to catastrophic failures of the cable insulation system.

[0003] A large number of scholars have discussed the corrosion behavior and principle of high-voltage cable joints. For example, Xu Zhonglin et al. studied the electrochemical corrosion and water ingress defect diagnosis of the lead-sealed section of high-voltage cable joints, and studied the electrochemical reactions that occur in the electrolyte environment of the cable joints, resulting in the erosion of materials. Ye Guanhao et al. studied the deterioration analysis of high-voltage power cable joints, and studied the material damage caused by the combined action of stress, self-defects or environmental factors in high-voltage power cable joints. The above studies deeply explored the action mechanism of hydrogen evolution, corrosion or failure of cable materials caused by mass exchange, ion migration or physical and chemical properties of surface microstructure. The above studies are mainly based on the simple mechanism of 2H2O + 2e - →2OH - + H2 and 2H + + 2e - → H2. However, theoretically analyzed, there are still a large number of free radical reaction processes with reducing and strong oxidizing properties in the electrochemical process. In this regard, the existing research has not explored and studied this. Summary of the Invention

[0004] The purpose of the present invention aims to solve the above problems existing in the prior art, and provides an experimental device and method for hydrogen evolution corrosion of high-voltage cable joints to realize the influence analysis of free radicals in the process of hydrogen evolution corrosion.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions.

[0006] The present invention provides an experimental device for hydrogen evolution corrosion of a high-voltage cable intermediate joint, which includes:

[0007] A hydrogen production test platform for testing metal sheets and EVA sheets of a metal / EVA structure in a simulated cable joint under different current density conditions and testing the generated hydrogen; the hydrogen production test platform includes a first sealed container, an AC power supply, a hydrogen sensor and a display terminal; the first sealed container contains a first electrolyte solution; the metal sheet and the EVA sheet are fixed in the first electrolyte solution through electrode clips; the hydrogen sensor extends into the sealed container; the output end of the hydrogen sensor is connected to the display terminal; the AC power supply is electrically connected to the metal sheet and the EVA sheet respectively through electrode clips.

[0008] An electrochemical test platform for performing electrochemical tests on the metal sheet of the metal / EVA structure in the simulated cable joint before and after hydrogen production.

[0009] In one implementation, the first electrolyte solution is a NaCl solution with a pH of 7.0 - 7.5, an ion concentration of 500 mg / L, and a conductivity of 1100 - 1150 μS / m.

[0010] In one achievable manner, the sizes of the metal sheet and the EVA sheet are both 2.0 cm × 1.5 cm × 0.02 cm. The metal sheet is an Al sheet or a Cu sheet.

[0011] In one achievable manner, the electrochemical test platform includes an electrochemical analyzer and a second sealed container; the second sealed container contains a second electrolyte solution; three electrodes are arranged in the second electrolyte solution, namely a metal sheet, a platinum electrode and a reference electrode; the three electrodes are all connected to the electrochemical analyzer.

[0012] In one achievable manner, the second electrolyte solution is pure water.

[0013] In one achievable manner, the electrochemical tests include open circuit potential, electrochemical impedance spectroscopy and Tafel curve tests.

[0014] The present invention also provides an experimental method for hydrogen evolution corrosion of a high-voltage cable intermediate joint, which includes the following steps:

[0015] S1, determining the hydrogen production current density threshold of the metal / EVA structure;

[0016] S2, setting the current density experimental conditions according to the determined hydrogen production current density threshold, energizing the combination of the metal sheet and the EVA sheet, and obtaining a hydrogen production curve;

[0017] S3. Before hydrogen production, add a radical scavenger to the first electrolyte. Then, under the experimental conditions of a set current density, apply an electric current to the combination of the metal sheet and the EVA sheet, and perform ultraviolet-visible spectrophotometer detection at set time intervals to obtain the change in the concentration of the radical scavenger, thereby determining the types of radicals.

[0018] S4. Before hydrogen production, add a radical quencher to the first electrolyte. Then, under the experimental conditions of a set current density, apply an electric current to the combination of the metal sheet and the EVA sheet, and obtain a hydrogen production curve to further determine the types of radicals.

[0019] In the above step S3, the radical scavenger is methylene blue (MB) or 5,5-dimethyl-1-pyrroline-N-oxide (DMPO). When the radical scavenger is 5,5-dimethyl-1-pyrroline-N-oxide, electron paramagnetic resonance testing (EPR) is performed while conducting hydrogen production testing to further determine the radicals.

[0020] In the above step S4, the radical quencher is absolute ethanol or chloroform.

[0021] Compared with the prior art, the hydrogen evolution corrosion experimental device and method for high-voltage cable joints provided by the present invention have the following beneficial effects:

[0022] 1. The present invention can analyze the role of radicals in the hydrogen evolution corrosion process of metals and EVA in high-voltage cable joints, providing effective data support for the analysis of the corrosion behavior and mechanism of high-voltage cable joints, and also providing a feasibility analysis for the fault diagnosis of high-voltage cable joints.

[0023] 2. The present invention can analyze the hydrogen evolution corrosion process of metals and EVA under the action of different radical quenchers and radical scavengers, clarify the types of radicals and their generation processes, as well as the mechanism of the action of radicals on material corrosion, which is of great significance for the corrosion of materials and the targeted selection, design, and application of corrosion inhibitors. Description of the Drawings

[0024] Figure 1 It is a schematic diagram of the structure of the hydrogen production test platform;

[0025] Figure 2 It is a schematic diagram of the structure of the electrochemical test platform;

[0026] Figure 3 It is the hydrogen production current threshold (a) of the metal sheet / EVA and the OCP test result (b) before hydrogen production of the metal sheet;

[0027] Figure 4 It is the hydrogen production curve of the metal sheet / EVA;

[0028] Figure 5 The removal rate curve of MB in the metal sheet / EVA system;

[0029] Figure 6 The EPR test spectrum of the metal sheet / EVA system;

[0030] Figure 7 The removal rate curve of MB after adding a radical quencher to the metal sheet / EVA system;

[0031] Figure 8 The OCP test results of the metal sheet / EVA after hydrogen production before and after adding a radical quencher;

[0032] Figure 9 The EIS test results of the metal sheet / EVA after hydrogen production before and after adding a radical quencher;

[0033] Figure 10 The Tafel curves of the metal sheet / EVA after hydrogen production before and after adding a radical quencher. Specific implementation manners

[0034] The technical solutions of 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 a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope protected by the present invention.

[0035] Embodiment

[0036] As Figure 1 - Figure 2 shown, this embodiment provides a hydrogen evolution corrosion experiment device for a high-voltage cable intermediate joint, which includes a hydrogen production test platform and an electrochemical test platform.

[0037] Hydrogen production test platform, which is used to test the metal sheet and EVA sheet of the metal / EVA structure in the simulated cable joint under different current density conditions and test the generated hydrogen. The sizes of the metal sheet and the EVA sheet are both 2.0 cm × 1.5 cm × 0.02 cm. The metal sheet is an Al sheet or a Cu sheet. The hydrogen production test platform includes a first sealed container 1, an AC power supply 2, a hydrogen sensor 3 and a display terminal 4. A first electrolyte is contained in the first sealed container 1; the first electrolyte is a NaCl solution with a pH of 7.0 - 7.5, an ion concentration of 500 mg / L, and a conductivity of 1100 - 1150 μS / m, which is used to simulate the water quality parameters of groundwater. The gaps of the first sealed container can be covered with silicone grease to enhance the sealing effect. The metal sheet and the EVA sheet are fixed in the first electrolyte through electrode clamps; the hydrogen sensor 3 extends into the sealed container; the output end of the hydrogen sensor is connected to the display terminal 4, and the display terminal is a computer, which is used to display the hydrogen concentration. The AC power supply 2 is electrically connected to the metal sheet and the EVA sheet respectively through electrode clamps; the working range of the AC power supply is set to 0 V to 330 V.

[0038] Electrochemical test platform, which is used to conduct electrochemical tests on the metal sheet of the metal / EVA structure in the simulated cable joint before and after hydrogen production. The electrochemical test platform includes an electrochemical analyzer 5 and a second sealed container 6. A second electrolyte is contained in the second sealed container 6; the second electrolyte is pure water. Three electrodes are arranged in the second electrolyte, which are the metal sheet, a platinum electrode and a reference electrode; the three electrodes are all connected to the electrochemical analyzer 5. The electrochemical tests include open circuit potential (OCP), electrochemical impedance spectroscopy (EIS) and Tafel curve test. The OCP test time is 100 s, the upper and lower limits of the EIS test frequency are 0.1 - 1.0×10 5 Hz, and the Tafel curve voltage test range is -1.0 V to 1.0 V. Since the Tafel test is a destructive test while the OCP and EIS tests are non-destructive tests, the test sequence for the same metal sheet sample is OCP, EIS and Tafel.

[0039] This embodiment also provides a method for hydrogen evolution corrosion experiment of a high-voltage cable intermediate joint, which includes the following steps:

[0040] S1, determine the hydrogen production current density threshold of the metal / EVA structure.

[0041] Before the hydrogen production experiment, the metal sheet and the EVA sheet are rinsed three times with ethanol and water respectively, and then dried. The metal sheet and the EVA sheet are fixed in 100 mL of the first electrolyte in the first sealed container through platinum sheet electrode clamps to simulate the metal / EVA structure in the cable joint.

[0042] To study the hydrogen production current density threshold of the metal / EVA structure, a small and constant current density was first applied in the experiment. If the sensor did not detect a signal within 5 minutes, the current density was gradually increased, and it was observed again whether the hydrogen sensor produced a signal within 5 minutes. This process was repeated until the current density increased to a level where the hydrogen sensor signal could be observed within 5 minutes. At this point, the current density was regarded as the hydrogen production current density threshold of this combination. After determining the threshold, different current density experimental conditions could be set by adjusting the AC power supply. The hydrogen production current density threshold results for the two combined interfaces are as follows Figure 3 (a) shown. Under the set conditions, the thresholds of the Al / EVA combination and the Cu / EVA combination are approximately 54 A / m 2 and 200 A / m 2 .

[0043] At the same time, OCP tests were carried out on samples identical to the above metal sheets. The results are as follows Figure 3 (b) reflects the OCP values of the metal materials in the two combinations before the hydrogen production experiment. The stable open-circuit potentials of Al and Cu are -0.961 V and -0.264 V respectively. Research shows that the more negative the open-circuit potential value of the material, the higher its corresponding Fermi level, and then the stronger the ability of the material to transfer electron-hole pairs at the solution surface, and the easier it is for the material to be oxidized. The open-circuit potential value of Al before the hydrogen production reaction is significantly more negative than that of Cu, and it is easier to lose electrons and become the anode material to produce hydrogen corrosion. Therefore, only a small current density is required for Al / EVA to corrode and evolve hydrogen.

[0044] S2. According to the determined hydrogen production current density threshold, the current density experimental conditions were set, and the combination of the metal sheet and the EVA sheet was energized to obtain the hydrogen production curve.

[0045] Experiments were carried out on the Al / EVA combination and the Cu / EVA combination under the conditions of 1.0 times and 3.0 times their respective hydrogen production current density thresholds. The results are as follows Figure 4As shown. As the reaction time increases, the hydrogen evolution rate of both combinations gradually decreases and finally reaches saturation. The reason may be that during the reaction, the corrosion products on the metal surface during the hydrogen evolution process continuously accumulate, resulting in a continuous increase in the resistivity of the combination interface. Moreover, the accumulation of corrosion products will continuously cover and reduce the reaction sites, thereby slowing down the reaction until it finally stops. At higher current densities, the hydrogen evolution rates of both combinations at the same moment increase significantly, and the final saturated hydrogen evolution concentration also increases substantially. This is because the greater the current density, the more severe the electrochemical corrosion of the metal sheet, and the higher the hydrogen evolution efficiency. Comparatively speaking, the hydrogen evolution rate and saturated hydrogen evolution concentration of Al / EVA are significantly higher than those of Cu / EVA, which may be due to the fact that the OCP value of Al is much more negative than that of Cu, and it is easier to lose electrons and has a faster electron transfer rate during the electrochemical corrosion process.

[0046] Through this step, the current density conditions required during the hydrogen production process can be determined. To better investigate the role of free radicals, subsequent experiments were all carried out at three times the hydrogen production current density threshold of each.

[0047] S3. Before hydrogen production, add a free radical scavenger to 100 mL of the first electrolyte, and then, under the experimental conditions of the set current density, apply electricity to the combination of the metal sheet and the EVA sheet. According to the set time intervals, perform ultraviolet-visible spectrophotometer detection to obtain the change in the concentration of the free radical scavenger, thereby determining the types of free radicals.

[0048] To deeply explore the generation of free radicals during the hydrogen evolution corrosion process of typical metal / EVA combinations in cable joints, methylene blue (MB) was selected as the free radical scavenger. MB is a colorimetric reagent for p-sulfonamide benzene. Its molecule contains a chromogenic group of ammonia sulfur with a lone pair of electrons connected to the benzene ring and has an electron-withdrawing property. MB has a maximum absorption peak at the absorption wavelength of 664 nm. When it accepts the electrons of oxidizing free radicals, it will be oxidized to methylsulfonyl with an absorption wavelength less than 180 nm. Moreover, during the process of MB being oxidized and removed, the color of the solution changes from blue to colorless, which is extremely convenient for observation or detection by spectrophotometry, and has ideal convenience and stability for free radical detection.

[0049] Before the hydrogen production experiment, add 0.22 micromoles of MB to 100 mL of the first electrolyte and start the hydrogen production experiment. At predetermined time intervals (0 min, 1 min, 3 min, 5 min, 7 min, 9 min, 11 min, 15 min, 20 min, and 30 min), collect 2 mL of the electrolyte in the electrolytic cell through a syringe, filter it using a water-based filter head with a filtration diameter of 0.22 μm to obtain the solution to be measured, and use an ultraviolet-visible spectrophotometer to detect it to obtain the corresponding absorbance to reflect the concentration of MB. Among them, C0 is the initial concentration of MB (at 0 min), C tis the concentration of MB at the remaining corresponding moments, denoted as C t / C0 reflects the removal rate of MB. The smaller the C t / C0 value, the more MB is removed, indicating that the oxidative free radicals generated in the system have a stronger effect.

[0050] The obtained MB removal rate curves are as shown in Figure 5 . Different degrees of MB removal (14.01% and 12.30%) occurred in both the Al / EVA and Cu / EVA systems, further proving that oxidative free radicals are generated during the hydrogen evolution corrosion process in both systems. The removal rate of MB in Al / EVA is faster than that in Cu / EVA, which may be due to the faster electron transfer rate between Al and EVA accelerating the generation of oxidative free radicals.

[0051] To further analyze the situation of free radicals, electron paramagnetic resonance (EPR) tests were conducted. The EPR technique is one of the commonly used means to detect and identify free radicals in a system. The types of free radicals present in the system can be inferred based on the response of specific characteristic peaks. 5,5-Dimethyl-1-pyrroline-N-oxide (DMPO) is one of the commonly used free radical scavengers. DMPO reacts with ·OH to form DMPO-OH, which is detected by EPR; similarly, DMPO reacts with hydrogen free radicals (·H) to form DMPO-H.

[0052] Before the hydrogen production experiment, 50 μL of DMPO was added to 100 mL of the first electrolyte and mixed evenly, and then the hydrogen production experiment was started. During the hydrogen evolution corrosion process of the two combinations, at the preset time nodes, 5 mL of the first electrolyte was taken for testing using the EPR technique. The obtained results are as shown in Figure 6 . By comparing and analyzing the standard DMPO-OH and DMPO-H spectra, ·OH signals were observed in the Al / EVA combination, and no obvious ·H signals were observed. In the Cu / EVA system, only weak ·H signals were observed. This may be because there are more ·OH in the Al / EVA combination system to resist the action of reducing ·H, while in the Cu / EVA combination system, fewer ·OH are quickly depolarized by ·H, so the signals are mainly ·H. In addition, the DMPO-X signal may be a by-product after DMPO is directly oxidized by the current.

[0053] S4. Before hydrogen production, a free radical quencher was added to the electrolyte, and then under the experimental conditions of a set current density, an electric current was applied to the combination of the metal sheet and the EVA sheet to obtain a hydrogen production curve to further determine the types of free radicals.

[0054] The free radical quencher used in this example is anhydrous ethanol (EtOH) and chloroform (TCM).

[0055] Anhydrous ethanol (EtOH) has the unique property of reacting rapidly with ·OH and is often used as an effective quencher for ·OH; chloroform (TCM) is often used for ·O2 - quenching. When ·O2 - participates in the removal of MB, the addition of TCM will inhibit the removal of MB.

[0056] Before each hydrogen production experiment, 1% (by volume fraction) of EtOH or TCM corresponding to the respective volume, and 0.22 μmol of MB were added to the first electrolyte, and then the hydrogen production experiment was started to evaluate the contributions of ·OH and ·O2 - The results are as Figure 7 shown. In the Al / EVA combination, the addition of EtOH and TCM reduced the removal rate of MB from 14.01% to 1.13% and 10.00% respectively. Similarly, in the Cu / EVA combination, the inhibitory removal effect of EtOH was better. The difference in the effects of the two quenchers indicates that in the metal / EVA combination, there may be oxidizing free radicals ·OH and ·O2 - , and ·OH is the main one.

[0057] Therefore, during the hydrogen evolution corrosion process of the metal / EVA structure of the cable intermediate joint, reducing free radical ·H and oxidizing free radicals mainly composed of ·OH will be generated.

[0058] This example also studied the role of the two metals during the hydrogen evolution corrosion process before and after adding the free radical quencher EtOH, and tested the OCP, EIS, and Tafel curves of the two metal sheets with and without the quencher added.

[0059] Before each hydrogen production experiment, 1% (by volume fraction) of EtOH was added to the first electrolyte, and then the hydrogen production experiment was started. After the experiment, the OCP, EIS, and Tafel curves of the metal sheet were tested. The results are as Figure 8 - 10 shown.

[0060] From Figure 8 it can be seen that for the OCP of the four test cases, as the test time extended, all showed a slightly positive shift and a tendency to stabilize. Compared with the OCP before hydrogen production ( Figure 3(b)), the OCP of Al changed from -0.961 V before hydrogen evolution to -0.049 V after hydrogen evolution, and the OCP of Cu changed from -0.261 V to 0.031 V. The positive shift of the OCP value is the result of the accumulation of corrosion products on the material surface inhibiting the anodic reaction. Therefore, the metal materials in the Al / EVA combination and the Cu / EVA combination were severely corroded during the hydrogen evolution process. It is worth noting that after adding a radical quencher before hydrogen evolution, the OCP value of Al after hydrogen evolution changed from -0.049 V to -0.447 V, and the OCP value of Cu changed from 0.031 V to -0.049 V, both showing a significant negative shift, indicating that the degree of corrosion of the material decreased.

[0061] Figure 9 reflects the EIS results of the material. In the equivalent circuit diagram, R s represents the impedance value inside the first electrolyte, and R ct represents the charge transfer resistance of the material, and W s represents the impedance generated by the ions diffusing back and forth between the electrode interface and the solution, and CPE is the double-layer capacitance. In the EIS spectrum, the arc in the high-frequency region corresponds to the initial chemical dissolution of the electrode material. The larger its radius, the greater the resistance to charge transfer, and the more severely it is electrochemically corroded. After adding the quencher, the arc radius in the high-frequency region of both Al and Cu decreased, indicating that the degree of electrochemical corrosion decreased. By fitting the EIS spectrum with Zview, the impedance values of the metal materials after hydrogen evolution with or without the quencher were obtained, as shown in Table 1. The addition of the quencher weakened the increasing trend of the charge transfer resistance R ct of Al and Cu after hydrogen evolution, and the total impedance value R 总 of the system was also smaller than that without the quencher.

[0062] Table 1 Fitted impedance values of metal sheet / EVA for metal materials after hydrogen evolution with or without quencher

[0063]

[0064] As Figure 10 shown, the Tafel curve was fitted using the electrochemical workstation CHI660E system to obtain the corresponding corrosion potential E corr , anodic slope b a , cathodic slope b c , and corrosion current J corr values, and the results are shown in Table 2. For the same material, E corr and J corr can reflect the degree of corrosion of the material. The more negative E corr is and the larger J corr is, the lighter the degree of corrosion of the material. In addition, for the same material, the anodic slope b aand the cathode slope b c The smaller it is, the larger the electron transfer coefficient will be, indicating that the degree of material corrosion is also lighter. The results in Table 2 are consistent with the results obtained from the previous OCP and EIS. The addition of the quencher significantly alleviates the corrosion of the metal sheet in the metal / EVA combination.

[0065] Table 2 Fitting results of Tafel curves

[0066]

[0067] Therefore, free radicals not only increase the hydrogen production rate and saturated hydrogen production amount of the material during the metal hydrogen evolution corrosion process, but also exacerbate the degree of material corrosion.

[0068] Those of ordinary skill in the art will realize that the embodiments herein are for helping the reader understand the principles of the present invention and should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those of ordinary skill in the art can make various other specific deformations and combinations without departing from the essence of the present invention based on these technical revelations disclosed in the present invention, and these deformations and combinations are still within the protection scope of the present invention.

Claims

1. An experimental device for hydrogen evolution corrosion of medium joints of high-voltage cables, characterized in that, Comprising: A hydrogen production test platform for testing the metal sheet and EVA sheet of the metal / EVA structure in a simulated cable joint under different current density conditions and testing the generated hydrogen; the hydrogen production test platform includes a first sealed container (1), an AC power supply (2), a hydrogen sensor (3) and a display terminal (4); a first electrolyte is contained in the first sealed container (1); the metal sheet and the EVA sheet are fixed in the first electrolyte by electrode clamps; the hydrogen sensor (3) extends into the sealed container; the output end of the hydrogen sensor is connected to the display terminal (4); the AC power supply (2) is electrically connected to the metal sheet and the EVA sheet respectively through electrode clamps; An electrochemical test platform for performing electrochemical tests on the metal sheet of the metal / EVA structure in a simulated cable joint before and after hydrogen production.

2. The hydrogen evolution corrosion experiment device for the middle joint of high-voltage cables according to claim 1, characterized in that, The first electrolyte is a NaCl solution with a pH of 7.0 - 7.5, an ion concentration of 500 mg / L, and a conductivity of 1100 - 1150 μS / m.

3. The hydrogen evolution corrosion test device for the high-voltage cable joint in the middle according to claim 1, characterized in that The metal sheet is an Al sheet or a Cu sheet.

4. The hydrogen evolution corrosion experiment device for the medium joint of high-voltage cables according to claim 1, wherein The electrochemical test platform includes an electrochemical analyzer (5) and a second sealed container (6); a second electrolyte is contained in the second sealed container (6); three electrodes are arranged in the second electrolyte, namely a metal sheet, a platinum electrode and a reference electrode; the three electrodes are all connected to the electrochemical analyzer (5).

5. The hydrogen evolution corrosion experimental device for the high-voltage cable joint in the middle according to claim 4, characterized in that, The second electrolyte is pure water.

6. An experimental method for hydrogen evolution corrosion of a high-voltage cable joint in the middle, characterized in that, Including the following steps: S1, determining the hydrogen production current density threshold of the metal / EVA structure; S2, according to the determined hydrogen production current density threshold, setting the current density experimental conditions, energizing the combination of the metal sheet and the EVA sheet, and obtaining the hydrogen production curve; S3, before hydrogen production, adding a radical scavenger to the first electrolyte, then under the set current density experimental conditions, energizing the combination of the metal sheet and the EVA sheet, and performing ultraviolet-visible spectrophotometer detection at set time intervals to obtain the change in the concentration of the radical scavenger, thereby determining the radical species; S4, before hydrogen production, adding a radical quencher to the first electrolyte, then under the set current density experimental conditions, energizing the combination of the metal sheet and the EVA sheet, and obtaining the hydrogen production curve to further determine the radical species.

7. The method for hydrogen evolution corrosion experiment of the medium joint of high-voltage cables according to claim 6, characterized in that, In step S3, the radical scavenger is methylene blue or 5,5-dimethyl-1-pyrroline-N-oxide; when the radical scavenger is 5,5-dimethyl-1-pyrroline-N-oxide, electron paramagnetic resonance test (EPR) is performed while performing the hydrogen production test to further determine the radical.

8. The hydrogen evolution corrosion experiment device for the middle joint of high-voltage cables according to claim 6, characterized in that, In step S4, the radical quencher is anhydrous ethanol or chloroform.

9. The hydrogen evolution corrosion experiment device for the middle joint of high-voltage cables according to claim 6, characterized in that, In step S4, the electrochemical test includes open circuit potential, electrochemical impedance spectroscopy and Tafel curve test.

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