On-load tap-changer testing device

Abstract

The utility model relates to an on-load tap-changer testing device, which comprises a tested branch, a harmonic current source branch, a follow current branch and a sampling trigger loop, and is characterized in that the harmonic current source branch comprises a high-voltage harmonic source and an adjustable multi-winding boosting transformer; the follow current branch comprises a bypass resistor and an energy absorption unit used for rapidly absorbing and consuming impact energy at the switching moment of the tap switch; the sampling trigger loop comprises an optical fiber trigger solid-state relay and a high-speed acquisition card. Through effective combination of all the components, the on-load tap-changer testing device can effectively simulate a complex harmonic environment in a large power grid, comprehensively and accurately tests the performance of the on-load tap-changer, and provides reliable technical support for operation and maintenance of power equipment. The problems that an existing testing device cannot accurately simulate a complex harmonic environment in actual operation, so that a testing result is inaccurate, and potential fault hidden dangers of the on-load tap-changer cannot be found in time are effectively solved.

Description

Technical Field

[0001] This application relates to the technical field of power equipment testing, and in particular to a test device for on-load tap changers. Background Technology

[0002] With the development of flexible DC technology, the operating conditions of on-load tap changers switching with harmonic currents are becoming increasingly prominent. On-load tap changers in converter stations need to operate frequently under complex conditions of multiple harmonic superposition. Because harmonic superposition leads to a shortening of the half-cycle of the transfer current and an increase in the zero-crossing steepness di / dt, it poses a great challenge to the current transfer capability of the vacuum interrupter, thus leading to an increase in the failure rate. This places higher demands on the reliability of the tap changer. Currently, IEC and GB standards are based on conventional DC research, but do not specify load switching test requirements with harmonic currents. Therefore, harmonic switching tests are required for the on-load tap changer of the converter transformer vacuum system to ensure the application performance of this device.

[0003] Especially in large power grids, the on-load tap changer of power transformers is a key device to ensure voltage stability and power quality, and its working status directly affects the safe operation of the power grid.

[0004] Chinese patent application CN202322565891.2 discloses an on-load tap changer testing device. This device includes a test branch, a harmonic current source branch connected in parallel to the test branch, and a freewheeling branch. A target current is generated from the 12kV power supply bus via a current-limiting inductor L. This target current flows through the switch under test on the test branch and back to the power supply bus to form a test circuit. The harmonic current source branch includes a low-voltage harmonic source HS and a step-up transformer T; the freewheeling branch includes a bypass resistor R; and a sampling trigger circuit is connected to the harmonic current source branch, with the sampling circuit connected to the test branch. This on-load tap changer testing device uses multiple harmonic combinations output from the low-voltage harmonic source to meet the di / dt test requirements, and then boosts the voltage output to achieve switch performance testing at different voltage levels.

[0005] The aforementioned technologies have the following drawbacks: Low-voltage harmonic source HS injects harmonic current through step-up transformer T. If step-up transformer T is a multi-winding transformer, although it can regulate the output to a certain extent, for large power grid transformers, the load characteristics are complex, and the required harmonic types and amplitude ranges are wide. Existing low-voltage harmonic sources cannot generate sufficiently strong and diverse harmonics, making it difficult to simulate the complex harmonic environment in actual operation. This leads to inaccurate test results and the inability to detect potential faults in on-load tap changers in a timely manner. Utility Model Content

[0006] To address the problem that existing testing devices cannot accurately simulate the complex harmonic environment in actual operation, resulting in inaccurate test results and the inability to detect potential faults in on-load tap changers in a timely manner, this application provides an on-load tap changer testing device.

[0007] The on-load tap changer testing device provided in this application adopts the following technical solution:

[0008] A test device for on-load tap changers includes a test branch, a harmonic current source branch, a freewheeling branch, and a sampling trigger circuit. The harmonic current source branch includes a high-voltage harmonic source and an adjustable multi-winding step-up transformer; the freewheeling branch includes a bypass resistor and an energy absorption unit for rapidly absorbing and dissipating impact energy during tap changer switching; and the sampling trigger circuit includes a fiber-optic triggered solid-state relay and a high-speed data acquisition card.

[0009] Furthermore, the high-voltage harmonic source adopts a modular design, which is used to combine modules according to different test requirements to generate specific harmonic currents.

[0010] Furthermore, the energy absorption unit is a superconducting energy storage unit, used to quickly respond to and absorb energy during tap changer switching.

[0011] Furthermore, the high-speed acquisition card simultaneously acquires current, vibration, and acoustic emission signals.

[0012] Furthermore, the testing device is equipped with an electromagnetic interference filter.

[0013] Furthermore, the outer casing of the testing device is made of conductive shielding material.

[0014] In summary, the beneficial technical effects of this application are as follows:

[0015] 1. By combining a modular high-voltage harmonic source with an adjustable multi-winding step-up transformer, a wide-spectrum harmonic of 0-5kHz can be generated (THD adjustable to 80%), accurately reproducing the complex operating conditions of the UHV power grid and improving the consistency between test results and actual operating conditions.

[0016] 2. The freewheeling branch integrates a bypass resistor and a superconducting energy storage unit, achieving nanosecond-level response through a parallel structure. This rapidly absorbs the impact energy during tap changer switching, suppressing the risk of overvoltage / overcurrent.

[0017] 3. The high-speed acquisition card simultaneously acquires current, vibration, and acoustic emission signals, breaking through the limitations of single signal analysis (such as traditional methods that rely solely on current waveforms) and improving the detection rate of complex faults;

[0018] 4. Environmental noise is filtered out by an electromagnetic interference filter to ensure signal acquisition accuracy; combined with a conductive shielding shell, electromagnetic interference is suppressed through a triple mechanism of reflection-absorption-scattering, further improving the stability of the test device in complex electromagnetic environments. Attached Figure Description

[0019] Figure 1 This is a wireframe diagram illustrating the logic structure and connection principle of this on-load tap changer test device;

[0020] Figure 2 This is a schematic diagram of the component connection circuit of the on-load tap changer test device.

[0021] Explanation of reference numerals in the attached figures:

[0022] 1. The tested branch;

[0023] 2. Harmonic current source branch; 21. High-voltage harmonic source; 22. Multi-winding step-up transformer;

[0024] 3. Freewheeling branch; 31. Bypass resistor; 32. Energy absorption unit;

[0025] 4. Sampling trigger circuit; 41. Solid-state relay; 42. High-speed data acquisition card;

[0026] 5. Electromagnetic interference filter. Detailed Implementation

[0027] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0028] This application discloses an on-load tap changer testing device. (Refer to...) Figure 1 and Figure 2The test circuit includes a test branch 1, a harmonic current source branch 2, a freewheeling branch 3, and a sampling trigger circuit 4. A target current is generated from the high-voltage power supply bus V via a current-limiting inductor L. This target current flows back to the power supply bus after passing through the switch under test in the test branch 1, forming the test circuit. The harmonic current source branch 2 includes a high-voltage harmonic source 21 and an adjustable multi-winding step-up transformer 22. The high-voltage harmonic source 21 can generate a wide range of high-intensity harmonic currents. Its output parameters, such as harmonic order, harmonic content, and harmonic current amplitude, can be set according to test requirements. The adjustable multi-winding step-up transformer 22 can flexibly adjust its output voltage and current to better simulate the complex harmonic environment in a large power grid. The freewheeling branch 3 includes a bypass resistor 31 and an energy absorption unit 32 for rapidly absorbing and dissipating impulse energy during tap changer switching. The energy absorption unit 32 uses a metal oxide surge arrester (MOA) or other components with the ability to rapidly absorb and dissipate impulse energy. The energy absorption unit 32 is connected in parallel with the bypass resistor 31 to the freewheeling branch 3. This allows the energy absorption unit 32 to respond quickly during tap changer switching, absorbing and dissipating the impact energy caused by sudden current changes, preventing overvoltage and overcurrent damage to the test equipment and transformer. The sampling trigger circuit 4 includes a fiber optic triggered solid-state relay 41 and a high-speed acquisition card 42. The fiber optic triggered solid-state relay 41 is installed in the test circuit to precisely control the triggering of test signals during testing. Trigger parameters of the solid-state relay 41, such as trigger time and trigger delay, can be set according to test requirements. The high-speed acquisition card 42 can acquire current, voltage, and other signals in the test circuit in real time, converting them into digital signals for processing and storage. During acquisition, appropriate sampling frequency and sampling accuracy are set to ensure that the acquired data accurately reflects the dynamic characteristics of the test circuit. The acquired data can be analyzed and processed by computer software to generate test reports and waveforms, providing a basis for evaluating the performance of the on-load tap changer under test.

[0029] During the testing of the on-load tap changer, the high-voltage power supply bus V is activated, allowing the target current to enter the test circuit through the current-limiting inductor L. A test signal is triggered via an optical fiber-triggered solid-state relay 41, initiating the test of the on-load tap changer. During the test, the high-voltage harmonic source 21 generates harmonic current, and the adjustable multi-winding step-up transformer 22 adjusts the output voltage and current to simulate the complex harmonic environment of a large power grid. The high-speed acquisition card 42 acquires current, voltage, and other signals in the test circuit in real time and transmits them to a computer for processing and storage. At the moment of tap changer switching, the bypass resistor 31 and energy absorption unit 32 in the freewheeling branch 3 function to absorb and dissipate the impact energy, preventing overvoltage and overcurrent from damaging the test equipment and transformer.

[0030] After the test is completed, the high-voltage power supply bus V is shut down, and the operation of the high-voltage harmonic source 21 and the adjustable multi-winding step-up transformer 22 is stopped. The collected data is analyzed and processed, current and voltage waveforms are plotted, and relevant parameters (such as harmonic content, overvoltage amplitude, and overcurrent amplitude) are calculated. Based on the analysis results, the performance of the on-load tap changer under test in a complex harmonic environment is evaluated, such as the dynamic characteristics during switching, insulation performance, and withstand voltage capability, and a test report is generated. This allows the on-load tap changer testing device to effectively simulate the complex harmonic environment in a large power grid, conduct comprehensive and accurate testing of the on-load tap changer's performance, and provide reliable technical support for the operation and maintenance of power equipment. It effectively improves the problem that existing testing devices cannot accurately simulate the complex harmonic environment in actual operation, resulting in inaccurate test results and the inability to promptly detect potential faults in on-load tap changers.

[0031] Specifically, refer to Figure 1 and Figure 2 The high-voltage harmonic source 21 adopts a modular design, allowing for the combination of modules to generate specific harmonic currents according to different testing requirements. This modular design enables the high-voltage harmonic source 21 to flexibly combine modules to generate specific harmonic currents, providing a more flexible and efficient testing method for on-load tap changer testing devices. Furthermore, because the modules are independent of each other, when a module fails, the faulty module can be quickly located and replaced, reducing maintenance time and costs.

[0032] Furthermore, referring to Figure 1 and Figure 2 The energy absorption unit 32 is a superconducting energy storage unit. The superconducting energy storage unit is mainly composed of a superconducting coil, a cryogenic container, a refrigeration system, a power regulation system, etc. It can quickly respond to and absorb the energy when the tap changer is switching, effectively protect the test device and transformer, improve test accuracy, and adapt to complex test environments.

[0033] Furthermore, referring to Figure 1 and Figure 2 The high-speed acquisition card 42 synchronously acquires current, vibration, and acoustic emission signals.

[0034] The high-speed data acquisition card 42 achieves synchronous acquisition of current, vibration, and acoustic emission signals by connecting to corresponding sensors. It has multiple sampling channels, each of which can independently set parameters such as sampling frequency and accuracy. Through a precise time synchronization mechanism, it ensures that the signals acquired by each channel are synchronized in time, thus accurately reflecting the interrelationships between different signals. Current signals can reflect the load condition and electrical performance of the on-load tap changer during switching. For example, a sudden change in current may indicate poor contact of the switch contacts or a short circuit.

[0035] Vibration signals are closely related to the mechanical movement of switches. Wear of switch contacts and loosening of mechanical parts can cause changes in vibration signals. By analyzing the frequency, amplitude, and other characteristics of the vibration signals, the mechanical condition of the switch can be determined.

[0036] Acoustic emission signals can monitor microscopic damage processes inside switches in real time, such as minute discharges in contacts and fatigue crack propagation in materials. These damage signals can often be captured by acoustic emission sensors in their early stages, providing a basis for early fault diagnosis of switches.

[0037] At the same time, refer to Figure 1 and Figure 2 The testing device is equipped with an electromagnetic interference filter 5. During on-load tap changer testing, the high-speed acquisition card 42 needs to simultaneously acquire multiple signals such as current, vibration, and acoustic emission. However, various electromagnetic interference sources exist in the testing environment, such as electromagnetic radiation generated by nearby power equipment and wireless communication equipment. These electromagnetic interferences will be superimposed on the acquired signals, causing signal distortion. The electromagnetic interference filter 5 can effectively filter out these interference signals, ensuring that the acquired current, vibration, and acoustic emission signals truly reflect the actual operating state of the on-load tap changer, improving the accuracy and reliability of signal acquisition. Furthermore, electromagnetic interference may affect the normal operation of the internal electronic components of the testing device, leading to device malfunction or performance degradation. The electromagnetic interference filter 5 can prevent interference signals from entering the circuit system of the testing device, protecting electronic components from interference and improving the stability and reliability of the testing device.

[0038] Additionally, refer to Figure 1 and Figure 2 The testing device's outer shell is made of conductive shielding material, such as copper, aluminum, or a conductive coating. When electromagnetic waves encounter the conductive shielding material, the material's excellent conductivity induces a current on its surface. According to the law of electromagnetic induction, this induced current generates a magnetic field opposite to the incident electromagnetic wave, thus reflecting part of the wave back. The unreflected electromagnetic waves enter the conductive shielding material and, while propagating within it, interact with free electrons, converting the wave's energy into heat, thereby absorbing it. When the electromagnetic wave is reflected multiple times between the two surfaces of the conductive shielding material, some energy is absorbed or scattered with each reflection, further reducing the wave's intensity. This suppresses electromagnetic interference, ensures signal integrity, and further improves the stability and reliability of the testing device.

[0039] The implementation principle of an on-load tap changer testing device according to an embodiment of this application is as follows:

[0040] During the testing of the on-load tap changer, the high-voltage power supply bus V is activated, allowing the target current to enter the test circuit through the current-limiting inductor L. A test signal is triggered via an optical fiber-triggered solid-state relay 41, initiating the test of the on-load tap changer. During the test, the high-voltage harmonic source 21 generates harmonic current, and the adjustable multi-winding step-up transformer 22 adjusts the output voltage and current to simulate the complex harmonic environment of a large power grid. The high-speed acquisition card 42 acquires current, voltage, and other signals in the test circuit in real time and transmits them to a computer for processing and storage. At the moment of tap changer switching, the bypass resistor 31 and energy absorption unit 32 in the freewheeling branch 3 function to absorb and dissipate the impact energy, preventing overvoltage and overcurrent from damaging the test equipment and transformer.

[0041] After the test is completed, the high-voltage power supply bus V is shut down, and the operation of the high-voltage harmonic source 21 and the adjustable multi-winding step-up transformer 22 is stopped. The collected data is analyzed and processed, current and voltage waveforms are plotted, and relevant parameters (such as harmonic content, overvoltage amplitude, and overcurrent amplitude) are calculated. Based on the analysis results, the performance of the on-load tap changer under test in a complex harmonic environment is evaluated, such as the dynamic characteristics during switching, insulation performance, and withstand voltage capability, and a test report is generated. This allows the on-load tap changer testing device to effectively simulate the complex harmonic environment in a large power grid, conduct comprehensive and accurate testing of the on-load tap changer's performance, and provide reliable technical support for the operation and maintenance of power equipment. It effectively improves the problem that existing testing devices cannot accurately simulate the complex harmonic environment in actual operation, resulting in inaccurate test results and the inability to promptly detect potential faults in on-load tap changers.

[0042] Unless otherwise defined, the technical or scientific terms used in this application shall have the ordinary meaning understood by one of ordinary skill in the art to which this application pertains. The terms "first," "second," "third," and similar terms used in this application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. The terms "an" or "a" and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms "comprising" or "including" and similar terms mean that the elements or objects preceding "comprising" or "including" encompass the elements or objects listed following "comprising" or "including" and their equivalents, and do not exclude other elements or objects. "Above," "below," "left," "right," etc., are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0043] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A test device for an on-load tap changer, comprising a test branch (1), a harmonic current source branch (2), a freewheeling branch (3), and a sampling trigger circuit (4), characterized in that, The harmonic current source branch (2) includes a high-voltage harmonic source (21) and an adjustable multi-winding step-up transformer (22); the freewheeling branch (3) includes a bypass resistor (31) and an energy absorption unit (32) for rapidly absorbing and consuming impact energy at the moment of tap changer switching; the sampling trigger circuit (4) includes an optical fiber triggered solid-state relay (41) and a high-speed acquisition card (42).

2. The on-load tap changer testing device according to claim 1, characterized in that, The high-voltage harmonic source (21) adopts a modular design, which is used to combine modules according to different test requirements to generate specific harmonic currents.

3. The on-load tap changer testing device according to claim 1, characterized in that, The energy absorption unit (32) is a superconducting energy storage unit used to quickly respond to and absorb energy during tap changer switching.

4. The on-load tap changer testing device according to claim 1, characterized in that, The high-speed acquisition card (42) synchronously acquires current, vibration, and acoustic emission signals.

5. The on-load tap changer testing device according to claim 1, characterized in that, The testing device is equipped with an electromagnetic interference filter (5).

6. The on-load tap changer testing device according to claim 1, characterized in that, The outer casing of the testing device is made of conductive shielding material.

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