A field test device for extra-high voltage converter transformer and an application method thereof

Abstract

The application discloses a kind of ultrahigh voltage converter transformer field test device and its application method, the present application includes three-phase alternating current test power supply, power supply compensation component, intelligent frequency conversion device, excitation variation compensation component, intermediate excitation transformer, converter transformer compensation component, measuring system and ultrahigh voltage converter transformer, the output end of three-phase alternating current test power supply is connected by the primary winding of intelligent frequency conversion device, excitation variation compensation component and intermediate excitation transformer, the secondary winding of intermediate excitation transformer is sequentially connected by the primary winding of converter transformer compensation component, measuring system and ultrahigh voltage converter transformer, the output end of three-phase alternating current test power supply is also grounded by power supply compensation component.The present application can be used for carrying out no-load test, load test and temperature rise test to ultrahigh voltage converter transformer in field station condition for converter station, to carry out internal multidimensional evaluation of ultrahigh voltage converter transformer in station based on test, improve the field operation and diagnosis capability of ultrahigh voltage converter.

Description

Technical Field

[0001] This invention belongs to the field of power equipment testing technology, specifically relating to an ultra-high voltage converter transformer field testing device and its application method. Background Technology

[0002] As the power generation and receiving ends of the ultra-high voltage direct current (UHVDC) transmission network, the converter transformer (such as the ±800kV converter transformer) plays a crucial role in UHVDC transmission projects. Due to the enormous size and weight of converter transformers, overall transportation is extremely difficult. Currently, a complex transportation method combining shipping and temporary road transport is mostly used. Returning them to the factory for performance evaluation is not only costly but also carries significant risks. Due to the special nature of transportation, a series of processes such as oil sampling and vacuuming are required for the UHV converter transformers, resulting in discrepancies between the internal condition of the returned transformers and the actual condition on-site. Therefore, on-site performance evaluation and testing of converter transformers at the converter station has become an inevitable choice for equipment operation and maintenance. Decades have passed since the earliest converter stations were built, and these stations have entered the equipment aging stage. A certain number of long-operating converter transformers urgently need to undergo no-load and load loss or temperature rise performance testing. Because converter transformers operate at full load for extended periods, they are more susceptible to various forms of deterioration, such as loosening and strand breakage, due to the combined effects of internal electrical, thermal, and mechanical stresses. This can lead to overheating damage and consequently, deterioration in no-load, load, and temperature rise performance. To more effectively test and diagnose converter transformers and make informed equipment management decisions, a comprehensive on-site evaluation of their electrical performance is necessary. No-load loss, load loss, and temperature rise performance are essential components of converter transformer electrical performance in various testing procedures. Currently, UHV converter transformers are tested at the plant using generators to directly increase voltage and current, enabling power frequency no-load and load loss testing. However, the large space within the substation, the wide distribution of various compensation devices, and the significant voltage differences make centralized testing difficult. Consequently, only low-frequency temperature rise performance testing is conducted on-site at the converter transformer substation, which is insufficient to fully verify the transformer's electrical performance. Existing no-load and load testing methods are inadequate for accurately identifying internal faults and defects in UHV converter transformers, thus hindering a precise assessment of their internal condition.

[0003] Due to the large number of devices and limited space within UHV converter stations, it is difficult to have the ample space available for arranging relevant testing equipment and devices under test, as is the case in factories. The large space within UHV converter stations, for example, means that the distance between high-voltage reactors and high-voltage capacitors is too great to directly utilize for centralized testing and evaluation of UHV converter transformers. Furthermore, converter transformers differ from AC transformers. AC transformers have a large voltage ratio between the primary and secondary sides, facilitating frequency doubling no-load testing, while converter transformers are divided into valve side and grid side, with a relatively small voltage ratio between the two, making no-load performance testing and evaluation of converter transformers more challenging. Simultaneously, conducting load performance testing and evaluation of UHV converter transformers places higher demands on compensation components and power supply capacity. Therefore, currently, only low-frequency testing of UHV converter transformers is conducted on-site within the station, and load testing is not performed. In addition, due to the complex internal structure of converter transformers, simple no-load, load, and temperature rise tests are insufficient to determine internal defects. Multiple methods, including testing, are needed to conduct on-site testing of the converter transformer's no-load and load performance to determine internal defects. The actual testing of no-load and load loss performance of converter transformers in converter stations is extremely difficult and lacks corresponding diagnostic basis. There is an urgent need to propose a method to conduct no-load loss, load loss and temperature rise tests using existing equipment inside the converter station, and to carry out multi-dimensional internal evaluation based on no-load and load tests, so as to improve the on-site operation, maintenance and diagnostic capabilities of UHV converter transformers. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an ultra-high voltage converter transformer field test device and its application method, which can be used to conduct no-load test, load test and temperature rise test on converter transformers in converter stations under field conditions, so as to carry out internal multi-dimensional evaluation of ultra-high voltage converter transformers in the station based on the test, and improve the field operation and maintenance and diagnosis capabilities of ultra-high voltage converter transformers.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A field testing device for an ultra-high voltage converter transformer includes a three-phase AC test power supply, a power compensation component, an intelligent frequency converter, an excitation transformer compensation component, an intermediate excitation transformer, a converter transformer compensation component, a measurement system, and the ultra-high voltage converter transformer under test. The output terminals of the three-phase AC test power supply are sequentially connected to the primary winding of the intermediate excitation transformer via the intelligent frequency converter, the excitation transformer compensation component, and the intermediate excitation transformer. The secondary winding of the intermediate excitation transformer is sequentially connected to the primary winding of the ultra-high voltage converter transformer via the converter transformer compensation component, the measurement system, and the primary winding of the ultra-high voltage converter transformer. The output terminals of the three-phase AC test power supply are also grounded via the power compensation component. The power compensation component includes capacitors C corresponding to each phase line. The measurement system includes a primary AC current transformer A and a primary AC voltage transformer V. The primary AC current transformer A is connected in series in the circuit containing the valve-side winding VA of the ultra-high voltage converter transformer under test, and the primary AC voltage transformer V is connected in parallel in the circuit containing the valve-side winding VA of the ultra-high voltage converter transformer under test.

[0006] Optionally, the three-phase AC test power supply is a generator car or station transformer used to output an adjustable AC voltage signal.

[0007] Optionally, the adjustable voltage range of the AC voltage signal output by the three-phase AC test power supply is 180V~400V.

[0008] Optionally, the excitation transformer compensation component is composed of an inductor and a capacitor connected in series, and the excitation transformer compensation component is connected in parallel to the primary winding of the intermediate excitation transformer to perform voltage boosting compensation on the intermediate excitation transformer to ensure that the three-phase AC test power supply and the intelligent frequency converter have sufficient capacity to carry out relevant tests. The excitation transformer compensation component is inductive during no-load test and capacitive during load test.

[0009] Optionally, the converter transformer compensation component is used to compensate for the reactive power required for the valve-side winding of the converter transformer to be suspended when the UHV converter transformer is under no-load conditions, and to compensate for the reactive power required for the grid-side winding of the converter transformer to be short-circuited under load and temperature rise conditions. During the no-load test, the UHV converter transformer is under capacitive load, and the converter transformer compensation component includes several series-parallel inductors; during the load test, the UHV converter transformer is under inductive load, and the converter transformer compensation component includes several series-parallel capacitors.

[0010] Optionally, the inductor used in the converter transformer compensation component during the no-load test is a DC smoothing reactor located in the station.

[0011] Optionally, the capacitor used in the converter transformer compensation component during the load test is an AC filter capacitor from within the station.

[0012] Optionally, the measurement system further includes a primary power measuring device W, which is installed on the circuit containing the valve-side winding VA of the UHV converter transformer under test.

[0013] Optionally, the UHV converter transformer is the test object. During the no-load test, the grid-side winding NS of the UHV converter transformer is connected to the secondary winding of the intermediate excitation transformer, and the valve-side winding VA is left floating. During the load test, the valve-side winding VA of the UHV converter transformer is connected to the secondary winding of the intermediate excitation transformer, and the grid-side winding NS is short-circuited to ground.

[0014] The present invention also provides a method for applying the aforementioned field testing device for ultra-high voltage converter transformers, comprising the following steps: S1, conduct no-load test on the ultra-high voltage converter transformer; S2, determine whether the no-load loss meets the requirements. If it does not meet the requirements, it is determined that there is a defect in the core components of the UHV converter transformer, and the process ends and exits; otherwise, jump to step S3. S3, determine whether the temperature rise of the no-load test meets the requirements. If it does not meet the requirements, it is determined that there is a defect in the non-core component of the UHV converter transformer, and jump to step S5; otherwise, jump to step S4. S4. Determine whether the oil chromatography and partial discharge of the UHV converter transformer meet the requirements. If both the oil chromatography and partial discharge meet the requirements, it is determined that the UHV converter transformer has no defects and the process ends and exits; otherwise, proceed to step S6. S5, determine whether the oil chromatography of the UHV converter transformer is an overheating defect. If so, determine that the UHV converter transformer has an overheating defect in non-core components and jump to step S6; otherwise, determine that the UHV converter transformer has a partial discharge defect in non-core components and needs to perform partial discharge diagnosis and location, end and exit. S6, Perform load tests on ultra-high voltage converter transformers; S7, determine whether the load loss meets the requirements. If it does not meet the requirements, determine that there is a defect in the winding components of the UHV converter transformer, end and exit; otherwise, jump to step S8. S8. Determine whether the temperature rise of the load test meets the requirements. If it does not meet the requirements, it is determined that there is a defect in the non-winding components of the UHV converter transformer, and the process jumps to step S10; otherwise, the process jumps to step S9. S9. Determine whether the oil chromatography and partial discharge of the UHV converter transformer meet the requirements. If both the oil chromatography and partial discharge meet the requirements, the UHV converter transformer is determined to be defect-free. If the partial discharge does not meet the requirements, the UHV converter transformer is determined to have partial discharge defects in non-winding components, requiring partial discharge diagnosis and location. End and exit. S10: Determine whether the oil chromatography of the UHV converter transformer indicates an overheating defect. If so, determine that the UHV converter transformer has an overheating defect in non-winding components; otherwise, determine that the UHV converter transformer has a partial discharge defect in non-core components, requiring partial discharge diagnosis and location. End and exit.

[0015] Compared with existing technologies, the present invention has the following main advantages: The UHV converter transformer field test device of the present invention includes a three-phase AC test power supply, a power compensation component, an intelligent frequency converter, an excitation transformer compensation component, an intermediate excitation transformer, a converter transformer compensation component, a measurement system, and the UHV converter transformer under test. The UHV converter transformer field test device of the present invention (three-phase AC power supply, converter transformer compensation component, and measurement system) can solve the problem of the inability to test existing power supplies and compensation components in the station due to large spatial distances by utilizing the primary AC equipment and connecting components such as busbars, GIS, switches, and disconnectors in the UHV converter station. Thus, it is possible to carry out on-site no-load, load, and temperature rise tests of the UHV converter transformer in the converter station. Based on the above tests, combined with the online monitoring device and live monitoring methods in the converter transformer field, it is used to diagnose internal defects of the UHV converter transformer caused by current and to conduct a detailed evaluation of the internal condition of the UHV converter transformer. Attached Figure Description

[0016] Figure 1 The diagram shows the test circuit wiring for the device in this embodiment of the invention to perform a no-load test, where A is a primary AC current transformer, V is a primary AC voltage transformer, W is a primary power measuring device, NS is the grid-side winding, and VS is the valve-side winding.

[0017] Figure 2 The diagram shows the test circuit wiring for load testing of the device in this embodiment of the invention, where A is a primary AC current transformer, V is a primary AC voltage transformer, W is a primary power measuring device, NS is the grid-side winding, and VS is the valve-side winding.

[0018] Figure 3 This is a schematic diagram of the process for evaluating the performance of an ultra-high voltage converter transformer using the device in an embodiment of the present invention. Detailed Implementation

[0019] To enable those skilled in the art to better understand the present invention, the technical solutions in the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0020] like Figure 1 and Figure 2As shown, this embodiment provides an ultra-high voltage converter transformer field test device, including a three-phase AC test power supply 1, a power compensation component 2, an intelligent frequency converter 3, an excitation transformer compensation component 4, an intermediate excitation transformer 5, a converter transformer compensation component 6, a measurement system 7, and an ultra-high voltage converter transformer 8 under test. The output terminal of the three-phase AC test power supply 1 is sequentially connected to the primary winding of the intermediate excitation transformer 5 through the intelligent frequency converter 3, the excitation transformer compensation component 4, and the intermediate excitation transformer 5. The secondary winding of the intermediate excitation transformer 5 is sequentially connected to the converter transformer compensation component 6 and the measurement system. The three-phase AC test power supply 1 is connected to the primary winding of the UHV converter transformer 8. The output terminal of the three-phase AC test power supply 1 is also grounded through the power compensation component 2. The power compensation component 2 includes capacitors C corresponding to each phase line. The measurement system 7 includes a primary AC current transformer A and a primary AC voltage transformer V. The primary AC current transformer A is connected in series in the circuit where the valve side winding VA of the UHV converter transformer 8 under test is located. The primary AC voltage transformer V is connected in parallel in the circuit where the valve side winding VA of the UHV converter transformer 8 under test is located. Figure 1 and Figure 2 In the diagram, AC~ represents the three-phase AC test power supply 1, C represents the power compensation component 2, IFI represents the intelligent frequency converter 3, and C... E For excitation transformer compensation component 4, T1 is intermediate excitation transformer 5, C V 6 is the converter transformer compensation component, 7 is the measurement system, and 8 is the ultra-high voltage converter transformer.

[0021] In this embodiment, the three-phase AC test power supply 1 is a generator vehicle used to output an adjustable AC voltage signal. The adjustable range of the AC voltage signal output by the generator vehicle is 180V~400V, which can be quickly deployed to relatively open sites near the converter transformer, is not limited by weather conditions, and can provide a stable power supply for a short time by adjusting the output cable to adapt to specific terrain conditions. In addition, when the power of the station service transformer and other conditions for commissioning are met, the three-phase AC test power supply 1 can also be a station service transformer.

[0022] In this embodiment, the power compensation component 2 includes capacitors C corresponding to the three-phase lines. The output terminals of the three-phase AC test power supply 1 are grounded through capacitors C on the three-phase lines. The power compensation component 2 is connected in parallel with the three-phase AC test power supply 1 to eliminate harmonics transmitted during the UHV converter transformer test, ensuring that the three-phase AC test power supply 1 itself is not interfered with by harmonics, and at the same time ensuring that the harmonics in its overall output voltage meet the test requirements. Together with the intelligent frequency converter 3, it achieves an effective and stable voltage output.

[0023] In this embodiment, the intelligent frequency converter 3 can adjust the operating frequency of the test power supply, reduce the inrush current during no-load testing, quickly adapt to the current distortion under commutator saturation, and ensure that the test power supply meets the requirements of the regulations. The intelligent frequency converter 3 is connected to the three-phase AC test power supply 1 and is used to adjust the output of the three-phase AC power supply to obtain the power frequency or slightly higher output voltage. The intelligent frequency converter 3 is composed of highly reliable power electronic devices, which can eliminate the influence of harmonics and output distortion under current saturation as much as possible.

[0024] In this embodiment, the excitation transformer compensation component 4 consists of an inductor and a capacitor connected in series, and is connected in parallel to the primary winding of the intermediate excitation transformer 5. This is used to compensate for the voltage increase of the intermediate excitation transformer 5, ensuring that the three-phase AC test power supply 1 and the intelligent frequency converter 3 have sufficient capacity to conduct relevant tests. During no-load testing, the excitation transformer compensation component 4 is inductive; during load testing, it is capacitive. The excitation transformer compensation component 4 is used to compensate for the higher harmonics in the intermediate excitation transformer 5 during the voltage increase process, as converter transformers are more prone to saturation and have higher harmonics than AC transformers. This ensures that the intelligent frequency converter 3 and the power supply have sufficient capacity to conduct relevant tests. Similar to the converter transformer compensation component 6, the compensation component is inductive during no-load testing and capacitive during load testing. The inductor in the excitation transformer compensation component 4 is a controllable multi-stage inductor element. That is, under normal circumstances, the excitation transformer compensation component 4 can be kept resistive by adjustment. Under no-load test conditions, the stage is reduced according to the actual frequency to reduce its inductive reactance. Similarly, under load test conditions, the stage is increased according to the actual frequency to increase its inductive reactance.

[0025] In this embodiment, the intermediate excitation transformer 5 is used to boost the AC voltage signal to the required test voltage and output a test voltage signal, which is then transmitted to the UHV converter transformer 8 to be tested. The high-voltage side of the intermediate excitation transformer 5 includes fully insulated double windings that can be connected in series or in parallel.

[0026] In this embodiment, the converter transformer compensation component 6 is used to compensate for the reactive power required for the valve-side winding of the UHV converter transformer 8 to be suspended under no-load conditions, and to compensate for the reactive power required for the grid-side winding of the converter transformer to be short-circuited under load and temperature rise conditions. During the no-load test, the UHV converter transformer 8 is a capacitive load, and the converter transformer compensation component 6 includes several series-parallel inductors. During the load test, the UHV converter transformer 8 is an inductive load, and the converter transformer compensation component 6 includes several series-parallel capacitors. In this embodiment, the inductor used in the converter transformer compensation component 6 during the no-load test is a DC smoothing reactor from within the station. The capacitor used in the converter transformer compensation component 6 during the load test is an AC filter capacitor from within the station.

[0027] In this embodiment, the measurement system 7 is used to measure and analyze data such as voltage and current at the input terminal of the converter transformer under test, and transmits the relevant data to the no-load test intelligent data processing and control backend. The processing and control backend controls and adjusts the intelligent frequency converter 3 according to the measurement results, and organizes and analyzes the test results of the converter transformer. Figure 1 and Figure 2 As shown, in this embodiment, the measurement system 7 also includes a primary power measurement device W, which is installed on the circuit where the valve-side winding VA of the UHV converter transformer 8 under test is located.

[0028] In this embodiment, the UHV converter transformer 8 is the test object. During the no-load test, the grid-side winding NS of the UHV converter transformer 8 is connected to the secondary winding of the intermediate excitation transformer 5, and the valve-side winding VA is left floating. During the load test, the valve-side winding VA of the UHV converter transformer 8 is connected to the secondary winding of the intermediate excitation transformer 5, and the grid-side winding NS is short-circuited to ground.

[0029] like Figure 1As shown, during the no-load test of the UHV converter transformer 8, a system including a three-phase AC test power supply 1, a power compensation component 2, an intelligent frequency converter 3, an excitation transformer compensation component 4, an intermediate excitation transformer 5, a converter transformer compensation component 6, a measurement system 7, the UHV converter transformer 8, and an intelligent data processing and control backend for the no-load test is employed. The AC voltage signal output from the generator (three-phase AC test power supply 1) passes through the power compensation component 2, then through the intelligent frequency converter 3, and is connected in parallel with the excitation transformer compensation component 4 to the input side (low-voltage side, primary winding) of the intermediate excitation transformer 5. The output side (high-voltage side, secondary winding) of the intermediate excitation transformer 5 is connected to the grid side of the UHV converter transformer 8 after passing through the excitation transformer compensation component 4, with the valve side of the UHV converter transformer 8 open-circuited. The power compensation component 2, connected between the generator and the intelligent frequency converter 3, can filter out third, fifth, and higher harmonics, reducing the waveform distortion rate during the no-load test and ensuring the normal conduction of the test. The excitation transformer compensation component 4 is connected between the intelligent frequency converter 3 and the intermediate excitation transformer 5. It consists of inductors and capacitors of different parameters connected in series, exhibiting inductive properties, and performs reactive power compensation on the low-voltage side. The converter transformer compensation component 6 is connected between the intermediate excitation transformer 5 and the UHV converter transformer 8 under test. It consists of multiple series and parallel inductors, performing reactive power compensation on the high-voltage side of the excitation transformer (i.e., the main test circuit), thereby reducing the total current in the test circuit while ensuring that the voltage across the converter transformer grid reaches the test voltage. A primary AC current transformer A is connected in series with the grid-side winding of the UHV converter transformer 8 under test, and a primary AC voltage transformer V is connected in parallel with the grid-side winding of the UHV converter transformer 8 under test. Real-time test data is transmitted from the equipment's own secondary data to the intelligent data processing and control backend. The backend calculates electrical data such as phase difference, active power, reactive power, and total power. It also integrates non-electrical data such as oil temperature and winding temperature from the converter transformer itself, forming a more comprehensive test data collection and analysis.

[0030] like Figure 2As shown, while the system composition and working principle of the load test and temperature rise test are the same, the devices used for the no-load test of the UHV converter transformer 8 differ from those used for the test. The system includes a three-phase AC test power supply 1, a power compensation component 2, an intelligent frequency converter 3, an excitation transformer compensation component 4, an intermediate excitation transformer 5, a converter transformer compensation component 6, a measurement system 7, the UHV converter transformer 8, and an intelligent data processing and control backend for the no-load test. The AC voltage signal output from the generator (three-phase AC test power supply 1) passes through the power compensation component 2, then through the intelligent frequency converter 3, and is connected in parallel to the excitation transformer compensation component 4, before being connected to the input side (low-voltage side) of the intermediate excitation transformer 5. The output side (high-voltage side) of the intermediate excitation transformer 5 is connected to the grid side of the UHV converter transformer 8 after passing through the excitation transformer compensation component 4, and the valve side of the UHV converter transformer 8 is open-circuited. Power compensation component 2 is connected between the generator car and the intelligent frequency converter 3. It can filter out third, fifth, and higher harmonics, reduce the waveform distortion rate of the load test, and ensure the normal conduction of the test. At this time, the parallel capacitor value is adjusted according to actual needs. Excitation transformer compensation component 4 is connected between the intelligent frequency converter 3 and the intermediate excitation transformer 5. It specifically includes inductors and capacitors with different parameters connected in series, forming a capacitive circuit, to perform reactive power compensation on the low-voltage side. Converter transformer compensation component 6 is connected between the intermediate excitation transformer 5 and the UHV converter transformer 8 to be tested. It specifically includes multiple series and parallel capacitors to perform reactive power compensation on the high-voltage side of the excitation transformer (i.e., the main test circuit), so that the total current of the test circuit is reduced while ensuring that the terminal voltage on the valve side of the converter transformer reaches the test voltage. Primary AC current transformer A is connected in series in the valve side winding of the converter transformer T2 to be tested, and primary AC voltage transformer V is connected in parallel in the valve side winding of the UHV converter transformer 8 to be tested. The intelligent data processing and control backend is consistent with the no-load test, but the corresponding test control conditions are different, and the relevant settings need to be adjusted before the test.

[0031] The evaluation methods for UHV converter transformers mainly include: no-load tests and load tests. The no-load loss, load loss, and temperature rise performance are tested during both no-load and load tests. Online and offline oil chromatography detection is performed on the converter transformer before, after (and before) the no-load test, and after the load test. During both the no-load and load tests, infrared spectroscopy, pulsed current partial discharge, and ultra-high frequency partial discharge detection are conducted on the bushings and transformer body. In this embodiment, the no-load loss, load loss, and temperature rise performance correspond to the active power loss, winding temperature rise, and insulating oil temperature rise of the UHV converter transformer under no-load, load, and load tests, respectively. The evaluation method addresses the connection difficulties mentioned, utilizing primary connection components such as busbars, conduits, switches, and disconnectors of different voltage levels within the station. During no-load testing, the converter transformer valve side is single-sided suspended and single-sided grounded. The converter transformer grid side can be further connected to the station's smoothing reactor for inductance compensation via DC primary connection components. During load testing, the converter transformer grid side is short-circuited and grounded. The converter transformer valve side can be further connected to the station's AC filter field's capacitor compensation components via AC primary connection components. The application method of the UHV converter transformer field test device in this embodiment includes sequentially conducting no-load tests on the converter transformer and measuring no-load loss, temperature rise, and on / offline oil chromatography and partial discharge under no-load conditions; and load tests on the converter transformer and measuring loss, temperature rise, and on / offline oil chromatography and partial discharge under load conditions. Following the evaluation process, defects in core components, non-core components, winding components, and overheating and partial discharge defects in non-winding components can be obtained sequentially. Specifically, as follows... Figure 3 As shown, the application method of the UHV converter transformer field test device in this embodiment includes the following steps: S1, conduct no-load test on UHV converter transformer 8; S2, determine whether the no-load loss meets the requirements. If it does not meet the requirements, determine that there is a core component defect in the UHV converter transformer 8, end and exit; otherwise, jump to step S3. S3, determine whether the temperature rise of the no-load test meets the requirements. If it does not meet the requirements, it is determined that there is a non-core component defect in the UHV converter transformer 8, and the process jumps to step S5; otherwise, the process jumps to step S4. S4. Determine whether the oil chromatography and partial discharge of the UHV converter transformer 8 meet the requirements. If both the oil chromatography and partial discharge meet the requirements, it is determined that the UHV converter transformer 8 has no defects and the process ends and exits; otherwise, proceed to step S6. S5, determine whether the oil chromatogram of the UHV converter transformer 8 is an overheating defect. If so, determine that the UHV converter transformer 8 has an overheating defect in a non-core component and jump to step S6; otherwise, determine that the UHV converter transformer 8 has a partial discharge defect in a non-core component and needs to perform partial discharge diagnosis and location, end and exit. S6, Perform a load test on the UHV converter transformer 8; S7, determine whether the load loss meets the requirements. If it does not meet the requirements, determine that there is a winding component defect in the UHV converter transformer 8, end and exit; otherwise, jump to step S8. S8. Determine whether the temperature rise of the load test meets the requirements. If it does not meet the requirements, determine that there is a defect in the non-winding components of the UHV converter transformer 8 and jump to step S10; otherwise, jump to step S9. S9, determine whether the oil chromatography and partial discharge of the UHV converter transformer 8 meet the requirements. If the oil chromatography and partial discharge both meet the requirements, the UHV converter transformer 8 is determined to be defect-free. If the partial discharge does not meet the requirements, the UHV converter transformer 8 is determined to have a partial discharge defect in a non-winding component, which requires partial discharge diagnosis and location. End and exit. S10, determine whether the oil chromatography of UHV converter transformer 8 indicates an overheating defect. If so, determine that UHV converter transformer 8 has an overheating defect in non-winding components; otherwise, determine that UHV converter transformer 8 has a partial discharge defect in non-core components and requires partial discharge diagnosis and location; end and exit.

[0032] The above method, through power output filtering and voltage regulation, dual compensation on the high and low voltage sides of the excitation transformer, and intelligent power electronic control, utilizes existing high-voltage reactive power compensation devices and primary AC measurement equipment within the station to meet the three most basic on-site tests of converter transformers: no-load, load, and temperature rise, eliminating the need to transport the converter transformer under test to the factory for testing. Relying on existing equipment within the station, including busbars, switches, and disconnectors, and by only requiring connections to the four outgoing lines of the converter transformer itself and the station service transformer and related busbars, the method minimizes the need for transporting and handling equipment, alleviating situations where space constraints prevent the conduct of related tests. This ensures the convenience of conducting no-load, load, and temperature rise tests on the converter transformer on-site, without the need for power meters. Utilizing intelligent harmonic devices to increase the frequency can correspondingly increase losses, resulting in a more accurate assessment of the no-load and load losses of the converter transformer. Leveraging the advantages of on-site testing of UHV converter transformers, real-time online / offline oil chromatography, infrared thermography and internal temperature gauges, and UHV / pulse current partial discharge detection can be performed on UHV converter transformers, thereby more accurately evaluating the internal faults and defects of UHV converter transformers.

[0033] The above descriptions are merely optional embodiments of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A field testing device for an ultra-high voltage converter transformer, characterized in that, The test system includes a three-phase AC test power supply, a power compensation component, an intelligent frequency converter, an excitation transformer compensation component, an intermediate excitation transformer, a converter transformer compensation component, a measurement system, and the UHV converter transformer under test. The output terminals of the three-phase AC test power supply are sequentially connected to the primary winding of the intermediate excitation transformer via the intelligent frequency converter, the excitation transformer compensation component, and the intermediate excitation transformer. The secondary winding of the intermediate excitation transformer is sequentially connected to the primary winding of the UHV converter transformer via the converter transformer compensation component, the measurement system, and the UHV converter transformer. The output terminals of the three-phase AC test power supply are also grounded through the power compensation component. The power compensation component includes capacitors C corresponding to each phase line. The measurement system includes a primary AC current transformer A and a primary AC voltage transformer V. The primary AC current transformer A is connected in series in the circuit containing the valve-side winding VA of the UHV converter transformer under test, and the primary AC voltage transformer V is connected in parallel in the circuit containing the valve-side winding VA of the UHV converter transformer under test.

2. The field test device for ultra-high voltage converter transformers according to claim 1, characterized in that, The three-phase AC test power supply is a generator car or station transformer used to output an adjustable AC voltage signal.

3. The field test device for ultra-high voltage converter transformers according to claim 2, characterized in that, The adjustable range of the AC voltage signal output by the three-phase AC test power supply is 180V~400V.

4. The field test device for ultra-high voltage converter transformers according to claim 1, characterized in that, The excitation transformer compensation component consists of an inductor and a capacitor connected in series, and is connected in parallel to the primary winding of the intermediate excitation transformer. It is used to step up the voltage of the intermediate excitation transformer to ensure that the three-phase AC test power supply and the intelligent frequency converter have sufficient capacity to carry out relevant tests. The excitation transformer compensation component is inductive during no-load test and capacitive during load test.

5. The field test device for ultra-high voltage converter transformers according to claim 1, characterized in that, The converter transformer compensation component is used to compensate for the reactive power required when the UHV converter transformer is under no-load conditions and when the UHV converter transformer is under load and temperature rise conditions, to compensate for the reactive power required when the converter transformer grid-side winding is short-circuited. During the no-load test, the UHV converter transformer is under capacitive load, and the converter transformer compensation component includes several series and parallel inductors. During the load test, the UHV converter transformer is under inductive load, and the converter transformer compensation component includes several series and parallel capacitors.

6. The field test device for ultra-high voltage converter transformers according to claim 5, characterized in that, The inductor used in the converter transformer compensation component during the no-load test is the DC smoothing reactor located in the station.

7. The field test device for ultra-high voltage converter transformers according to claim 5, characterized in that, The capacitor used in the load test of the converter transformer compensation component is the AC filter capacitor from the station.

8. The field test device for ultra-high voltage converter transformers according to claim 1, characterized in that, The measurement system also includes a primary power measuring device W, which is installed on the circuit containing the valve-side winding VA of the UHV converter transformer under test.

9. The field test device for ultra-high voltage converter transformers according to claim 1, characterized in that, The UHV converter transformer is the test object. During the no-load test, the grid-side winding NS of the UHV converter transformer is connected to the secondary winding of the intermediate excitation transformer, and the valve-side winding VA is left floating. During the load test, the valve-side winding VA of the UHV converter transformer is connected to the secondary winding of the intermediate excitation transformer, and the grid-side winding NS is short-circuited to ground.

10. A method for applying the field testing device for an ultra-high voltage converter transformer as described in any one of claims 1 to 9, characterized in that, Includes the following steps: S1, conduct no-load test on the ultra-high voltage converter transformer; S2, determine whether the no-load loss meets the requirements. If it does not meet the requirements, it is determined that there is a defect in the core components of the UHV converter transformer, and the process ends and exits. Otherwise, proceed to step S3; S3, determine whether the temperature rise of the no-load test meets the requirements. If it does not meet the requirements, it is determined that there is a defect in the non-core component of the UHV converter transformer, and jump to step S5. Otherwise, proceed to step S4; S4. Determine whether the oil chromatography and partial discharge of the UHV converter transformer meet the requirements. If both the oil chromatography and partial discharge meet the requirements, it is determined that the UHV converter transformer has no defects and the process ends and exits; otherwise, proceed to step S6. S5, determine whether the oil chromatography of the UHV converter transformer is an overheating defect. If so, determine that the UHV converter transformer has an overheating defect in non-core components and jump to step S6; otherwise, determine that the UHV converter transformer has a partial discharge defect in non-core components and needs to perform partial discharge diagnosis and location, end and exit. S6, Perform load tests on ultra-high voltage converter transformers; S7, determine whether the load loss meets the requirements. If it does not meet the requirements, determine that there is a defect in the winding components of the UHV converter transformer, end and exit; Otherwise, proceed to step S8; S8, determine whether the temperature rise of the load test meets the requirements. If it does not meet the requirements, determine that there is a defect in the non-winding components of the UHV converter transformer and jump to step S10. Otherwise, proceed to step S9; S9. Determine whether the oil chromatography and partial discharge of the UHV converter transformer meet the requirements. If both the oil chromatography and partial discharge meet the requirements, the UHV converter transformer is determined to be defect-free. If the partial discharge does not meet the requirements, the UHV converter transformer is determined to have partial discharge defects in non-winding components, requiring partial discharge diagnosis and location. End and exit. S10: Determine whether the oil chromatography of the UHV converter transformer indicates an overheating defect. If so, determine that the UHV converter transformer has an overheating defect in non-winding components; otherwise, determine that the UHV converter transformer has a partial discharge defect in non-core components, requiring partial discharge diagnosis and location. End and exit.

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