Platform and method for testing electrical performance of transformer insulation structure for offshore wind plant

Abstract

The invention discloses an electrical performance test platform and method for a transformer insulation structure for an offshore wind farm, and belongs to the technical field of offshore wind farms. The test platform comprises a real transformer, a high-voltage power supply unit, a measurement unit, a control unit and a data processing unit; through the construction of the real transformer, the working environment of the real transformer in an offshore wind plant can be simulated, and the insulation structure is enabled to complete the test in the working environment of the real transformer. The test platform is different from a traditional test mode, a high-reduction and high-simulation mode is adopted, a real transformer working environment is provided for an insulation structure, and the accuracy of a test result is ensured; the test result measured by the system can provide an important reference basis for the promotion work of the upgrading of the oil-immersed transformer; the system is simple in structure and principle and convenient to implement and operate, and has good popularization and application value.

Description

Technical Field

[0001] This invention belongs to the field of offshore wind farm technology, specifically to the field of oil-immersed transformer testing, and particularly relates to a test platform and method for the electrical performance of transformer insulation structure for offshore wind farms. Background Technology

[0002] Offshore wind farms refer to wind farms built in near-shore areas with a water depth of about 10 meters, utilizing the abundant wind energy resources at sea to generate electricity. Compared with onshore wind farms, offshore wind farms have advantages such as not occupying land resources, being largely unaffected by topography, higher wind speeds, abundant wind energy resources, larger single-unit capacity of wind turbines (3-5 MW), and higher annual utilization hours. Oil-immersed transformers, due to their compact structure, light weight, strong corrosion resistance, and excellent seismic performance, are particularly suitable for offshore wind farm applications, providing stable power support. Therefore, the stable and normal operation of oil-immersed transformers is crucial for offshore wind farms.

[0003] The performance of insulating oil has a significant impact on the normal operation and safe use of oil-immersed transformers; the requirements for the performance of transformer insulating oil are becoming increasingly stringent. Mineral oil and vegetable oil are two commonly used transformer insulating oils, and their insulation performance directly affects the operational safety and stability of the transformer. However, existing insulation performance testing platforms often cannot realistically simulate the transformer's working environment, leading to significant discrepancies between test results and actual conditions. Furthermore, the limitations of insulating oil electrical performance testing results hinder the advancement of oil-immersed transformer upgrades.

[0004] It is evident that existing insulation performance testing platforms often fail to accurately simulate the working environment of transformers, resulting in an inability to precisely measure the electrical properties of insulating oil. Summary of the Invention

[0005] To overcome the above-mentioned technical defects, the present invention provides a test platform and method for the electrical performance of the insulation structure of transformers used in offshore wind farms. The use of this system and method can solve the technical problem that existing insulation performance test platforms often cannot realistically simulate the working environment of transformers, resulting in the inability to accurately and effectively measure the electrical performance of insulating oil.

[0006] To achieve the above objectives, the present invention employs the following technical content:

[0007] An electrical performance testing platform for the insulation structure of a transformer used in offshore wind farms includes:

[0008] A full-scale transformer is used to simulate the working environment of a real transformer in an offshore wind farm, so that the insulation structure can be tested under the working environment of a real transformer.

[0009] A high-voltage power supply unit is connected to the real transformer and is used to provide high-voltage power to the real transformer to simulate the voltage conditions of the real transformer during normal operation.

[0010] The measurement unit is used to measure the test data in the full-scale transformer in real time; the test data includes the insulation resistance, absorption ratio, polarization index, test time, and partial discharge quantity corresponding to the insulation structure.

[0011] The control unit is connected to the real transformer, the high-voltage power supply unit and the measurement unit respectively, and is used to control the operation of the entire test platform;

[0012] The data processing unit is used to receive the test data from the measurement unit, process and analyze the test data, and generate a test report to evaluate the electrical performance of the insulation structure.

[0013] Furthermore, the true-type transformer includes: an oil tank, an iron core, windings, a cooling system, a tap changer, and an oil conservator;

[0014] The iron core is fixed in the oil tank by insulating gaskets and fasteners;

[0015] The winding is wound around the iron core and separated from the iron core by an insulating material;

[0016] The cooling system is connected to the oil tank and is used to guide the insulating structure into the radiator for cooling, and then return it to the oil tank for recycling.

[0017] The tap changer is installed on the high-voltage side of the full-size transformer;

[0018] The oil storage tank is located on top of the oil tank and is connected to the oil tank.

[0019] Furthermore, the iron core adopts a single-phase three-column structure; the winding includes a high-voltage winding and a low-voltage winding, wherein the high-voltage winding adopts an inner-screen continuous end-lead structure, and the low-voltage winding adopts a single-helix structure; the oil tank adopts a bell-type oil tank; the oil storage tank adopts a capsule-type oil storage tank; and the cooling system includes a fan and heat sinks.

[0020] Furthermore, the test platform also includes an oil sample processing unit connected to the full-scale transformer, used for heating, stirring, and temperature control of the insulation structure sample.

[0021] Furthermore, the oil sample processing unit includes a heating device, a stirring device, and a temperature control device located in the full-size transformer;

[0022] The heating device is used to heat the insulation structure sample so that the insulation structure sample reaches the preset test temperature.

[0023] The stirring device is used to stir the insulation structure sample to make the insulation structure sample uniform.

[0024] The temperature control device is electrically connected to the heating device and is used to monitor and adjust the temperature of the insulation structure in real time.

[0025] Furthermore, the measuring unit includes a current transformer, a voltage transformer, and a temperature sensor; the test data includes current, voltage, and temperature.

[0026] Furthermore, the insulating structure comprises mineral oil and vegetable oil.

[0027] Furthermore, the test report includes: a comparative analysis report on dielectric loss of mineral oil and vegetable oil, a comparative analysis report on capacitance between a full-scale transformer corresponding to mineral oil and a full-scale transformer corresponding to vegetable oil, and a comparative analysis report on insulation resistance between a full-scale transformer corresponding to mineral oil and a full-scale transformer corresponding to vegetable oil.

[0028] A method for operating a test platform for the electrical performance of transformer insulation structure in offshore wind farms, based on the aforementioned test platform, includes:

[0029] The control unit controls the full-scale transformer, high-voltage power supply unit, and measurement unit respectively. The insulation structure is injected into the full-scale transformer, simulating the working environment of a real transformer in an offshore wind farm. The high-voltage power supply unit outputs a preset test voltage to simulate the voltage conditions of the full-scale transformer during normal operation. During the test, the measurement unit measures the test data in the full-scale transformer in real time. Finally, the test data is transmitted to the data processing unit, which processes and analyzes the test data and generates a test report to evaluate the electrical performance of the insulation structure. The test data includes the insulation resistance, absorption ratio, polarization index, test time, and partial discharge quantity corresponding to the insulation structure.

[0030] Furthermore, the test process includes insulation characteristic test, switching impulse test, lightning impulse test, external withstand voltage test, line terminal AC withstand voltage test, and induced voltage test with partial discharge measurement.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] This invention provides a test platform for the electrical performance of transformer insulation structures used in offshore wind farms. The platform includes a full-scale transformer, a high-voltage power supply unit, a measurement unit, a control unit, and a data processing unit. By constructing a full-scale transformer, the operating environment of a real transformer can be simulated, allowing the insulation structure to be tested under the actual transformer's operating conditions. This test platform differs from traditional testing methods, employing a highly realistic and simulated approach to provide the insulation structure with a true transformer operating environment, ensuring the accuracy of the test results. The test results obtained using this system can provide important reference for promoting the upgrading of oil-immersed transformers. The system has a simple structure and principle, is easy to implement and operate, and has good application value.

[0033] Preferably, in this invention, the real-type transformer includes an oil tank, an iron core, windings, a cooling system, a tap changer, and an oil conservator. The iron core adopts a single-phase three-column structure, the high-voltage winding adopts an internally shielded continuous end-out terminal structure, and the low-voltage winding adopts a single-helix structure. The oil tank adopts a bell-type oil tank, and the oil conservator adopts a capsule-type oil conservator. The cooling system includes a fan and heat sinks. Through the optimized design of the above structures, the working environment requirements of a real-world transformer are met.

[0034] Preferably, in this invention, the platform is also equipped with an oil sample processing unit, which ensures the uniformity and temperature stability of the insulation structure sample during the test, and further realistically restores the actual working environment of the transformer.

[0035] Preferably, in this invention, the control unit can control the operation of the entire test platform, including setting and adjusting test parameters and collecting data. Operators can remotely control the operation, which improves test efficiency and the accuracy of test results, while reducing test safety hazards.

[0036] This invention also provides a working method for a test platform for the electrical performance of transformer insulation structures used in offshore wind farms. Based on the aforementioned test system, this method controls a full-scale transformer, a high-voltage power supply unit, and a measurement unit through a control unit. The insulation structure is injected into the full-scale transformer, simulating the working environment of a real transformer in an offshore wind farm. The high-voltage power supply unit outputs a preset test voltage to simulate the voltage conditions of the full-scale transformer during normal operation. During the test, the measurement unit measures the test data in the full-scale transformer in real time. Finally, the test data is transmitted to a data processing unit, which processes and analyzes the data and generates a test report to evaluate the electrical performance of the insulation structure. This working method is easy to implement, realistically simulates the actual working environment of the transformer, and ensures that the test process for the electrical performance of the insulation structure is conducted in a realistic environment, thus improving the accuracy of the evaluation. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the electrical performance testing platform for the insulation structure of a transformer used in an offshore wind farm, provided as an embodiment of the present invention. Detailed Implementation

[0038] To make the technical problems solved by the present invention, the technical solutions, and the beneficial effects clearer, the following specific embodiments provide a further detailed description of the present invention. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of the invention.

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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 some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0040] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0041] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0042] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0043] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0044] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0045] Example

[0046] As mentioned in the background section, the performance of insulating oil has a significant impact on the normal operation and safe use of oil-immersed transformers; the requirements for the performance of transformer insulating oil are becoming increasingly stringent. Mineral oil and vegetable oil are two commonly used transformer insulating oils, and their insulation performance directly affects the operational safety and stability of the transformer. However, existing insulation performance testing platforms often cannot realistically simulate the transformer's working environment, leading to significant discrepancies between test results and actual conditions. Furthermore, the limitations of insulating oil electrical performance testing results hinder the advancement of oil-immersed transformer upgrades.

[0047] To address the aforementioned issues, this embodiment provides a test platform for the electrical performance of transformer insulation structures used in offshore wind farms, such as... Figure 1 As shown, the specific structure includes:

[0048] The control unit is used to control the operation of the entire test platform; the real transformer is used to simulate the working environment of a real transformer in an offshore wind farm, which can ensure that the insulation structure is in the working environment of a real transformer to complete the test.

[0049] Here, the full-scale transformer includes: an oil tank, an iron core, windings, a cooling system, a tap changer, and an oil conservator. The iron core is fixed in the oil tank by insulating gaskets and fasteners. The windings are wound around the iron core and separated from it by insulating material. The cooling system is connected to the oil tank and is used to guide the insulating structure into a radiator for cooling, then return it to the oil tank for reuse. The tap changer is installed on the high-voltage side of the full-scale transformer. The oil conservator is located on top of the oil tank and is connected to it.

[0050] Specifically, the oil tank can withstand a full vacuum (residual pressure less than 13.3 Pa) and a pressure of 0.098 MPa without damage or unacceptable permanent deformation. The high-voltage winding has an end-out structure, and the core adopts a single-phase three-column (main column + side yoke) structure. The core is stacked using high-quality, low-loss, high-permeability laser-irradiated cold-rolled grain-oriented silicon steel sheets with fully oblique joints and stepped overlaps, ensuring uniform magnetic flux distribution at the joints and reducing no-load current and noise. The core columns are bound without holes, and each step is supported by round wooden struts to ensure the core is round and sturdy and provides uniform and reliable internal support to the low-voltage winding, improving short-circuit resistance. The core is secured with clamps, pull plates, pull straps, and binding straps, forming a rigid frame structure. Precise calculations are performed on the strength of each structural component under lifting, transportation, and short-circuit conditions to ensure sufficient strength to prevent the transformer from loosening due to vibration during lifting, transportation, operation, and short circuits. The high-voltage winding adopts an inner-shielded continuous type, while the low-voltage winding adopts a single-helix type. The insulation thickness of the conductor turns is selected based on an inter-turn working field strength ≤2000V / mm. The heating and temperature rise of the windings are calculated in advance, and the structure is optimized to ensure uniform oil flow distribution and good cooling, avoiding localized overheating. The leakage magnetic field of the windings is calculated, considering not only the windings but also the magnetic shielding, leads, and core. Sometimes, lead leakage magnetic field needs to be carefully considered, as it may cause localized overheating of adjacent structural components. Simultaneously, the losses and temperature rise of all components are calculated to prevent localized overheating of the windings and metal structural components. The windings are clamped by an integral pressure plate, and a clamping device is used between the pressure plate and the clamps to ensure that each winding receives the required clamping force. The winding leads are sufficiently robust, and the transformer body forms a solid whole with sufficient short-circuit withstand strength. A unique grounding system is used to reliably ground all clamps, pull plates, pull straps, magnetic shielding, and electrical shielding, eliminating circulating current loops and floating potentials. High-quality insulation materials are used, with high dielectric strength, good inter-turn impact resistance, and anti-aging properties. The oil tank adopts a bell-shaped design, which is simple and aesthetically pleasing and easy to install and maintain. A reliable design is adopted to prevent localized overheating of the oil tank and accessories. A capsule-type oil conservator is used, and the heat dissipation method is a combination of sheet cooling and a fan.

[0051] In this embodiment, the parameters of the real-type transformer are set as follows: capacity: 80 / 80MVA; rated voltage: (230 / √3) / 10.5kV; connection group: II0; cooling method: KNAN; noise level: ≤68dB(A); short-circuit impedance HL: 16% (±7.5%).

[0052] Insulation levels are as follows: hv: Line terminal - SI / LI / AC - 750 / 950 / 395kV; lv: Line terminal - LI / AC - 75 / 35kV; hv: Neutral point terminal - LI / AC - 400 / 200kV;

[0053] No-load loss: 55kW; Load loss: 260kW; Temperature rise limits are as follows: Top oil: 55K; Average winding: 65K; Hot spot in winding: 78K; Surface of oil tank, core and metal structural components: 78K;

[0054] Partial discharge level (at 1.58Ur / √3kV): High voltage ≤100pC; Low voltage ≤200pC;

[0055] The aforementioned transformer insulation structure electrical performance test platform also includes: a high-voltage power supply unit for providing high-voltage power to the real-type transformer, thereby simulating the voltage conditions of the real-type transformer during normal operation; a measurement unit for real-time measurement of test data in the real-type transformer and receiving the test data from the measurement unit, processing and analyzing the test data and generating a test report, thereby completing the evaluation of the electrical performance of the insulation structure.

[0056] Specifically, to ensure the uniformity and temperature stability of the insulation structure samples during the test and to further realistically reproduce the actual working environment of the transformer, the test platform is also equipped with an oil sample processing unit. This includes a heating device for heating the insulation structure samples to reach the preset test temperature; a stirring device for stirring the insulation structure samples to achieve uniformity; and a temperature control device electrically connected to the heating device for real-time monitoring and adjustment of the insulation structure temperature.

[0057] In this embodiment, the measurement unit includes a current transformer, a voltage transformer, and a temperature sensor; the current transformer measures current test data, the voltage transformer measures voltage test data, and the temperature sensor measures temperature data, and the above test data are transmitted to the data processing unit in real time.

[0058] Therefore, this test platform includes a full-scale transformer, a high-voltage power supply unit, a measurement unit, a control unit, and a data processing unit. By constructing a full-scale transformer, it can simulate the working environment of a real transformer, allowing the insulation structure to be tested under the actual working environment of a real transformer. This test platform differs from traditional test methods, employing a highly realistic and simulated approach to provide the insulation structure with a true transformer working environment, ensuring the accuracy of the test results. The test results obtained using this system can provide important reference for promoting the upgrading and replacement of oil-immersed transformers.

[0059] This embodiment also provides a working method for the transformer insulation structure electrical performance test platform, which specifically includes the following:

[0060] The control unit controls the full-size transformer, the high-voltage power supply unit, and the measurement unit respectively;

[0061] The insulation structure is injected into a real transformer to simulate the working environment of a real transformer; the preset test voltage is output through the high-voltage power supply unit to simulate the voltage conditions of a real transformer during normal operation.

[0062] During the test, the measurement unit measures the test data in the full-scale transformer in real time; and finally transmits the test data to the data processing unit.

[0063] The data processing unit processes and analyzes the data and generates a test report to evaluate the electrical performance of the insulation structure.

[0064] Specifically, the above-mentioned test process includes insulation characteristic test, switching impulse test, lightning impulse test, external withstand voltage test, line-end AC withstand voltage test, and induced voltage test with partial discharge measurement. The test standards referenced for the above tests are GB / T 1094.3-2017 and GB / T 1094.4-2013. Using this test method, mineral oil and vegetable oil were effectively tested and data analyzed on the transformer insulation structure electrical performance test platform provided in this embodiment. The test results for mineral oil are as follows: as shown in Tables 1, 2, 3, 4, and 5.

[0065] Table 1 shows the test results of the insulation properties of mineral oil.

[0066]

[0067] Table 2 shows the results of the lightning impact test on mineral oil.

[0068]

[0069]

[0070] Here, the lightning impulse test process specifically includes conducting lightning impulse tests on the test terminals and on the neutral point terminals, in the following order:

[0071] A. Test terminals: 1. One full-wave reference impact at 50% to 70% of full voltage; 2. One full-wave impact at 100% of full voltage; 3. One chopped-wave impact at 50% to 70% of full test voltage; 4. Two chopped-wave impacts at 100% of full voltage; 5. Two full-wave impacts at 100% of full voltage.

[0072] B. Neutral point terminal: 1. One full-wave impulse of 50% to 70% of the full test voltage; 2. Three full-wave impulses of 100% of the full voltage.

[0073] Table 3 shows the results of the external pressure resistance test of mineral oil.

[0074]

[0075] Table 4 shows the results of the AC withstand voltage test at the mineral oil line end.

[0076]

[0077] Table 5 shows the test results of induced voltage in mineral oil with partial discharge site measurement.

[0078]

[0079]

[0080] After completing the mineral oil test on the test platform according to the normal test sequence, the test was conducted using vegetable oil. First, the low-voltage test was completed, including voltage ratio measurement, connection group number verification, winding resistance measurement, insulation no-load loss and no-load current measurement, sound level determination, short-circuit impedance measurement, and load loss measurement. To fully utilize the full-scale model test platform and avoid breakdown discharge during the withstand voltage test that could prevent subsequent tests, the test sequence was adjusted based on comparative insulation test data and relevant literature provided by the vegetable oil manufacturer. The temperature rise test was conducted first. After this test, the system was allowed to stand for 48 hours before the high-voltage test, with the following test sequence:

[0081] 100% power frequency withstand voltage test → 100% line terminal withstand voltage test → 80% switching impact → 80% lightning impact → 85% lightning impact → 90% lightning impact → 100% lightning impact → 100% switching impact → 100% partial discharge test.

[0082] Specifically, the test results for vegetable oils are as follows: as shown in Tables 6, 7, 8, 9, and 10;

[0083] Table 6 shows the test results of the insulation properties of vegetable oil.

[0084]

[0085]

[0086] Table 7 shows the results of the operational impact test of vegetable oils.

[0087]

[0088] Table 8 shows the results of the lightning impact test on vegetable oil.

[0089]

[0090] Table 9 shows the results of the external pressure resistance test of vegetable oil.

[0091]

[0092] Table 10 shows the results of the AC withstand voltage test on the end of the vegetable oil wire.

[0093]

[0094] Table 11 shows the test results of induced voltage in vegetable oil with partial discharge site measurement.

[0095]

[0096] Based on the above experimental results, the comparison data between vegetable oil and mineral oil shows that:

[0097] First, the dielectric loss of a true transformer using vegetable oil is significantly greater than that using mineral oil. The dielectric loss factor refers to the energy loss within the insulating oil due to the hysteresis effect of dielectric conductivity and polarization. It depends on the number of ionizable components and polar molecules in the oil, and is also affected by the degree of oil refining. An increased dielectric loss factor indicates contamination of the insulating oil by moisture, charged particles, or soluble polar substances. It is highly sensitive to contamination during oil processing; for transformers, internal cleanliness is crucial. The dielectric loss factor of insulating oil is closely related to the content of oil-soluble polar impurities; even a small amount of polar impurities can lead to a significant increase in the dielectric loss factor. Because natural ester insulating oil is a mixture of esters mainly composed of fatty acid triglycerides, its polar molecules result in a higher dielectric loss than mineral oil. Aging products of the oil also contribute to an increased dielectric loss factor.

[0098] Second, the capacitance of a true transformer in vegetable oil is significantly greater than that in mineral oil. The main factor affecting capacitance is the relative permittivity, which is the ratio of the capacitance when the capacitor electrodes are completely filled with the test insulating material to the capacitance when the electrodes of the same shape are in a vacuum. The relative permittivity of liquid insulating materials depends largely on the test conditions, especially temperature and the frequency of the applied voltage. The relative permittivity is a measure of dielectric polarization and material conductivity.

[0099] Third, the insulation resistance of a true transformer impregnated with vegetable oil is significantly lower than that with mineral oil. Under the same conditions, the volume resistivity of plant-based materials is slightly lower than that of mineral oil. The volume resistivity of mineral oil-impregnated paper and natural ester oil-impregnated paper measured in oil is higher than that measured in air. The volume resistivity of vegetable oil-impregnated paper (paperboard) is about one-tenth that of mineral oil-impregnated paper (paperboard).

[0100] In summary, this invention provides a working method for a test platform for the electrical performance of transformer insulation structures used in offshore wind farms. Based on the aforementioned test system, this method controls the full-scale transformer, high-voltage power supply unit, and measurement unit through a control unit. The insulation structure is injected into the full-scale transformer, simulating the working environment of a real transformer. The high-voltage power supply unit outputs a preset test voltage to simulate the voltage conditions of the full-scale transformer during normal operation. During the test, the measurement unit measures the test data in the full-scale transformer in real time. Finally, the test data is transmitted to the data processing unit, which processes and analyzes the data and generates a test report to evaluate the electrical performance of the insulation structure. This working method is easy to implement and can realistically simulate the actual working environment of the transformer, ensuring that the test process for the electrical performance of the insulation structure is conducted in a realistic environment, thus improving the accuracy of the evaluation. It provides an important reference for promoting the upgrading of oil-immersed transformers.

[0101] The above embodiments are merely one of the implementation methods for achieving the technical solution of the present invention. The scope of protection claimed by the present invention is not limited to this embodiment, but also includes any variations, substitutions and other implementation methods that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention.

Claims

1. A test platform for the electrical performance of transformer insulation structure used in offshore wind farms, characterized in that, include: A full-scale transformer is used to simulate the working environment of a real transformer in an offshore wind farm, so that the insulation structure can be tested under the working environment of a real transformer. A high-voltage power supply unit is connected to the real transformer and is used to provide high-voltage power to the real transformer to simulate the voltage conditions of the real transformer during normal operation. The measurement unit is used to measure the test data in the full-scale transformer in real time; the test data includes the insulation resistance, absorption ratio, polarization index, test time, and partial discharge quantity corresponding to the insulation structure. The control unit is connected to the real transformer, the high-voltage power supply unit and the measurement unit respectively, and is used to control the operation of the entire test platform; The data processing unit is used to receive the test data from the measurement unit, process and analyze the test data, and generate a test report to evaluate the electrical performance of the insulation structure.

2. The electrical performance test platform for the insulation structure of transformers used in offshore wind farms according to claim 1, characterized in that, The full-scale transformer includes: an oil tank, an iron core, windings, a cooling system, a tap changer, and an oil conservator; The iron core is fixed in the oil tank by insulating gaskets and fasteners; The winding is wound around the iron core and separated from the iron core by an insulating material; The cooling system is connected to the oil tank and is used to guide the insulating structure into the radiator for cooling, and then return it to the oil tank for recycling. The tap changer is installed on the high-voltage side of the full-size transformer; The oil storage tank is located on top of the oil tank and is connected to the oil tank.

3. The electrical performance test platform for the insulation structure of transformers used in offshore wind farms according to claim 2, characterized in that, The iron core adopts a single-phase three-column structure; the winding includes a high-voltage winding and a low-voltage winding, wherein the high-voltage winding adopts an internally shielded continuous end-lead structure, and the low-voltage winding adopts a single-helix structure; the oil tank adopts a bell-shaped oil tank; the oil storage tank adopts a capsule-shaped oil storage tank; the cooling system includes a fan and heat sinks.

4. The electrical performance test platform for the insulation structure of transformers used in offshore wind farms according to claim 1, characterized in that, The test platform also includes an oil sample processing unit, which is connected to the full-scale transformer and is used to heat, stir, and control the temperature of the insulation structure sample.

5. The electrical performance test platform for the insulation structure of transformers used in offshore wind farms according to claim 4, characterized in that, The oil sample processing unit includes a heating device, a stirring device, and a temperature control device located in the full-size transformer. The heating device is used to heat the insulation structure sample so that the insulation structure sample reaches the preset test temperature. The stirring device is used to stir the insulation structure sample to make the insulation structure sample uniform. The temperature control device is electrically connected to the heating device and is used to monitor and adjust the temperature of the insulation structure in real time.

6. The electrical performance test platform for the insulation structure of transformers used in offshore wind farms according to claim 1, characterized in that, The measurement unit includes a current transformer, a voltage transformer, and a temperature sensor; the test data includes current, voltage, and temperature.

7. The electrical performance test platform for the insulation structure of transformers used in offshore wind farms according to claim 1, characterized in that, The insulating structure includes mineral oil and vegetable oil.

8. The electrical performance test platform for the insulation structure of transformers used in offshore wind farms according to claim 7, characterized in that, The test report includes: a comparative analysis report on the dielectric loss of mineral oil and vegetable oil, a comparative analysis report on the capacitance between a full-scale transformer corresponding to mineral oil and a full-scale transformer corresponding to vegetable oil, and a comparative analysis report on the insulation resistance values ​​between a full-scale transformer corresponding to mineral oil and a full-scale transformer corresponding to vegetable oil.

9. A method for operating a test platform for the electrical performance of the insulation structure of a transformer used in an offshore wind farm, based on the test platform for the electrical performance of the insulation structure of a transformer used in an offshore wind farm as described in any one of claims 1-8, characterized in that, include: The control unit controls the real transformer, the high-voltage power supply unit and the measurement unit respectively. The insulation structure is injected into the real transformer. The real transformer is used to simulate the working environment of a real transformer in an offshore wind farm. The high-voltage power supply unit outputs a preset test voltage to simulate the voltage conditions of the real transformer during normal operation. During the test, the measurement unit measures the test data in the full-scale transformer in real time; finally, the test data is transmitted to the data processing unit, which processes and analyzes the test data and generates a test report to evaluate the electrical performance of the insulation structure; wherein, the test data includes the insulation resistance, absorption ratio, polarization index, test time, and partial discharge quantity corresponding to the insulation structure.

10. The working method of the electrical performance test platform for the insulation structure of a transformer used in an offshore wind farm according to claim 9, characterized in that, The testing process includes insulation characteristic test, switching impulse test, lightning impulse test, external withstand voltage test, line terminal AC withstand voltage test, and induced voltage test with partial discharge measurement.

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