A partial discharge measurement system under harmonic voltage

Abstract

The present invention discloses a partial discharge measurement system under the action of harmonic voltage, comprising a harmonic voltage test transformer and a plurality of measurement units connected in series with the harmonic voltage test transformer, each measurement unit further comprising a filter, a partial discharge test piece and a measurement impedance, and the harmonic voltage filtered by the filter sequentially passes through the partial discharge test piece and the measurement impedance and then is grounded. The partial discharge measurement system of the present invention studies the influence of multiple harmonic components on the same test piece in one test, thereby improving the speed of the research test. In addition, the defect of changing the state of the test piece due to frequent adjustment of the frequency of the test power supply is avoided, so that the result of the discharge measurement test is more accurate.

Description

Technical Field

[0001] The invention relates to a partial discharge measurement system under the action of harmonic voltage, belonging to the field of electrical test equipment. Background Art

[0002] During operation, DC equipment such as converter transformers not only withstand conventional AC voltage, but also special types of electrical stress such as AC / DC and harmonics.

[0003] Especially under harmonic voltage, it will cause increased losses and insulation damage. Previous studies have studied the partial discharge characteristics of oil-paper insulation or gas insulation under a single 50Hz power frequency voltage or pure DC voltage, and have accumulated a lot of experience. However, for the study of partial discharge characteristics under harmonic voltage, due to the rich harmonic content, it is often difficult to independently separate the voltages of different harmonic components, especially it is impossible to study the effects of multiple harmonic components on the same test product in one test, which has led to less research on partial discharge under harmonic voltage. In addition, the existing technology also needs to frequently adjust the test power supply frequency to test the effects of multiple different harmonic components on the same batch of test products.

[0004] However, the process of frequently adjusting the frequency of the test power supply will change the state of the test product. Summary of the invention

[0005] Purpose of the invention: The present invention provides a partial discharge measurement system under the action of harmonic voltage, which avoids the change of the test product state caused by frequent adjustment of the frequency of the test power supply.

[0006] Technical solution: The technical solution adopted by the present invention is a partial discharge measurement system under the action of harmonic voltage, including a harmonic voltage test transformer and at least one measurement unit connected in series with the harmonic voltage test transformer, each measurement unit includes a filter, a partial discharge test piece and a measurement impedance, and the harmonic voltage filtered by the filter passes through the partial discharge test piece and the measurement impedance in sequence and then is grounded.

[0007] The voltage signal generated by the harmonic voltage test transformer contains different harmonic components.

[0008] The three measuring units are connected in series with the harmonic voltage test transformer.

[0009] The filters in the three measuring units are all passive filters.

[0010] The measurement impedance is 50 ohms.

[0011] The passive filters are all high-pass filters.

[0012] The -3dB frequencies of the three passive filters are 75 Hz, 125 Hz and 175 Hz respectively.

[0013] A method for measuring partial discharge under the action of harmonic voltage comprises the following steps:

[0014] 1) Perform the first high-pass filtering on the signal emitted by the test power supply, and connect the filtered signal to the partial discharge test product corresponding to the first high-pass filtering;

[0015] 2) Perform a second high-pass filter on the signal after the previous step of filtering, and connect the filtered signal to the partial discharge test piece corresponding to the second high-pass filter;

[0016] 3) Perform a third high-pass filter on the signal filtered in the previous step, and connect the filtered signal to the partial discharge specimen corresponding to the third high-pass filter.

[0017] The -3dB frequency of the first high-pass filtering is 75 Hz, the -3dB frequency of the second high-pass filtering is 125 Hz, and the -3dB frequency of the third high-pass filtering is 175 Hz.

[0018] Beneficial effects: The partial discharge measurement system of the present invention studies the influence of multiple harmonic components on the same test product in one test, thereby improving the speed of the research test. In addition, it avoids the defect of frequently adjusting the frequency of the test power supply to change the state of the test product, making the results of the discharge measurement test more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the structure of the measurement system of the present invention. DETAILED DESCRIPTION

[0020] like Figure 1 As shown, this embodiment proposes a partial discharge measurement system under harmonic voltage, including a harmonic voltage test transformer 1, a first passive filter 2, a second passive filter 3 and a third passive filter 4, a first partial discharge test piece 5, a second partial discharge test piece 7 and a third partial discharge test piece 9, a first measuring impedance 6, a second measuring impedance 8 and a third measuring impedance 10, and an oscilloscope 11.

[0021] The harmonic voltage test transformer 1 is a test power supply, which generates various test voltages, each of which is composed of a plurality of harmonic components superimposed. In the present embodiment, the harmonic components generated by the harmonic voltage test transformer 1 include 50Hz, 100Hz, 150Hz and 200Hz. These harmonic voltages pass through the first passive filter 2, the second passive filter 3 and the third passive filter 4 in sequence. Different passive filters have different passband and stopband ranges, which can filter out harmonics of specific frequencies. Among them, the first passive filter 2 is a high-pass filter with a -3dB frequency of 75Hz. The second passive filter 3 is a high-pass filter with a -3dB frequency of 125Hz. The third passive filter 4 is a high-pass filter with a -3dB frequency of 175Hz.

[0022] A partial discharge test piece is connected to the output end of each passive filter, and the first partial discharge test piece 5, the second partial discharge test piece 7 and the third partial discharge test piece 9 are connected to the first passive filter 2, the second passive filter 3 and the third passive filter 4 respectively. The other end of each partial discharge test piece is grounded through a corresponding measuring impedance. The first measuring impedance 6, the second measuring impedance 8 and the third measuring impedance 10 are connected to the first partial discharge test piece 5, the second partial discharge test piece 7 and the third partial discharge test piece 9 respectively. The connection point of each partial discharge test piece and its corresponding measuring impedance is used as a measuring point of an oscilloscope 11, and the discharge signal of the connection point is introduced into the oscilloscope 11 for measurement.

[0023] The first passive filter 2 filters out the 50Hz fundamental wave, so the 100Hz, 150Hz and 200Hz harmonic components are all applied to the first partial discharge specimen 5. The second passive filter 3 continues to filter out the 100Hz harmonic component, so the 150Hz and 200Hz harmonic components are all applied to the second partial discharge specimen 7. The third passive filter 4 further filters out the 150Hz harmonic component, and the 200Hz harmonic component is applied to the third partial discharge specimen 9.

[0024] The partial discharge test pieces in this embodiment may be test pieces with the same structure, and are used to study the influence of different harmonic components on the partial discharge of a certain test piece.

[0025] It is also possible to use specimens with different structures to study the sensitivity of different specimen structures to harmonic components, that is, to study the sensitivity of the first partial discharge specimen 5 to 100Hz, 150Hz and 200Hz harmonics; the sensitivity of the second partial discharge specimen 7 to 150Hz and 200Hz harmonics; and the sensitivity of the third partial discharge specimen 9 to 200Hz harmonics.

[0026] In this way, the test voltage containing multiple harmonic components is applied to different partial discharge samples at the same time, and the test of individual harmonic components or combinations of harmonic components on the discharge samples is completed at one time, and the voltage of the test power supply can be repeatedly changed to obtain the results of the influence of different harmonic components on the partial discharge samples. In this embodiment, a test voltage containing multiple harmonic components can also be applied to the same partial discharge sample to test the influence of different harmonic components on a certain partial discharge sample.

[0027] In addition, the system also avoids the change of partial discharge specimen state caused by frequent adjustment of single test power supply frequency in existing test methods. This state change is mainly the change of space charge, which will lead to changes in the discharge characteristics of the partial discharge specimen.

[0028] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0029] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0030] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0031] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0032] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A partial discharge measurement system under harmonic voltage, characterized by: The invention comprises a harmonic voltage test transformer (1) and at least one measuring unit connected in series with the harmonic voltage test transformer (1), each measuring unit comprising a filter, a partial discharge test piece and a measuring impedance, the harmonic voltage filtered by the filter passes through the partial discharge test piece and the measuring impedance in sequence and then is grounded; the voltage signal generated by the harmonic voltage test transformer (1) contains different harmonic components; the harmonic voltage test transformer (1) is connected in series with three measuring units, the filters in the three measuring units are all passive filters, different passive filters have different passband and stopband ranges, and are used to filter out harmonics of specific frequencies.

2. The partial discharge measurement system under harmonic voltage according to claim 1 is characterized in that: The measurement impedance is 50 ohms.

3. The partial discharge measurement system under harmonic voltage according to claim 1 is characterized in that: The passive filters are all high-pass filters.

4. The partial discharge measurement system under harmonic voltage according to claim 3 is characterized in that: The -3dB frequencies of the three passive filters are 75 Hz, 125 Hz and 175 Hz respectively.

5. A method for measuring partial discharge under the action of harmonic voltage based on the system according to any one of claims 1 to 4, characterized in that: The following steps are involved: 1) performing a first high-pass filtering on the signal emitted by the harmonic voltage test transformer (1), and connecting the filtered signal to the partial discharge test piece corresponding to the first high-pass filtering; 2) Perform a second high-pass filter on the signal after the previous step of filtering, and connect the filtered signal to the partial discharge test piece corresponding to the second high-pass filter; 3) Perform a third high-pass filter on the signal after the previous step of filtering, and connect the filtered signal to the partial discharge test sample corresponding to the third high-pass filter; The test voltage generated by the harmonic voltage test transformer (1) is formed by the superposition of multiple harmonic components, and the third-order high-pass filtering has different -3dB frequencies to filter out harmonics of specific frequencies.

6. The method for measuring partial discharge under harmonic voltage according to claim 5, characterized in that: The -3dB frequency of the first high-pass filtering is 75 Hz, the -3dB frequency of the second high-pass filtering is 125 Hz, and the -3dB frequency of the third high-pass filtering is 175 Hz.

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