A method, device and storage medium for judging the aging state of a lightning arrester

Abstract

The present invention discloses a method, device and storage medium for judging the aging state of a lightning arrester, comprising: performing impact aging on a varistor of the lightning arrester under different impact current amplitudes and cooling it to room temperature; recording the varistor under different current amplitude impacts at an initial power frequency reference voltage u 1mAI The leakage current and its resistive component are measured; harmonic characteristics analysis is performed on the leakage current and its resistive component current waveform data based on FFT to obtain the fundamental amplitude and each higher harmonic amplitude; the ratio of the even harmonics of the resistive component of the leakage current to the fundamental amplitude is determined as the optimal index, and according to the above steps, the optimal index is obtained for arresters of different voltage levels, and the harmonic characteristics of the impact aging of the arrester varistor are further determined to obtain the online monitoring judgment criteria for the aging state of the arrester of the corresponding voltage level. The present invention can effectively monitor the state of the zinc oxide arrester in real time.

Description

Technical Field

[0001] The present invention relates to the electric power field, and in particular to a method, a device and a storage medium for determining the aging state of a lightning arrester. Background Art

[0002] With the continuous development of society, safe and reliable power supply is the primary task of the power system. As one of the important devices to suppress overvoltage caused by internal operation or lightning strike, lightning arresters have been widely used in power systems due to their excellent nonlinear characteristics, huge current capacity and no series gap. At present, the 500kV AC filter lightning arresters in some ±800kV and ±500kV converter stations in my country have frequent actions. In addition, due to the heat accumulation during the long-term operation of the lightning arresters, frequent impact current will cause the lightning arresters to be damaged and out of operation. Therefore, it is necessary to conduct accelerated aging tests on zinc oxide varistors used in AC filter lightning arresters under impact current to provide a basis for the aging evaluation standards of AC filter lightning arresters in UHV DC transmission systems.

[0003] At present, most of the aging criteria and online monitoring indicators of ZnO varistors are based on the DC reference voltage U 1mA , nonlinear coefficient, residual voltage ratio, leakage current and its odd harmonics, etc. Most of them can only identify the arrester status by measuring the DC reference voltage and residual voltage of the zinc oxide arrester in preventive tests. They belong to offline monitoring methods and cannot monitor the zinc oxide arrester status in real time. Summary of the invention

[0004] In order to overcome the above-mentioned shortcomings and deficiencies of the prior art, the purpose of the present invention is to provide a method, device and storage medium for judging the aging state of a lightning arrester, specifically relating to a method for judging the aging state of a lightning arrester based on the impact aging harmonic characteristics of ZnO varistor sheets by means of experiments.

[0005] The present invention adopts the following technical solution:

[0006] A method for determining the aging state of a lightning arrester includes the following steps:

[0007] The arrester varistor was subjected to impact aging at different impact current amplitudes and cooled to room temperature;

[0008] Record the voltage of the varistor at the initial power frequency reference voltage u under different current amplitude shocks 1mAI The leakage current and its resistive component are measured, and the waveform data of the leakage current and its resistive component are saved;

[0009] Based on FFT, the harmonic characteristics of the leakage current and its resistive component current waveform data are analyzed to obtain the fundamental wave amplitude and each higher harmonic amplitude;

[0010] The leakage current and its resistive component higher harmonic to fundamental amplitude ratio are obtained, and the optimal index for judging the aging state of the varistor is obtained. The optimal index is the initial power frequency voltage u 1mAI The ratio of the even harmonics of the resistive component of the lower leakage current to the fundamental amplitude;

[0011] According to the above steps, the optimal index is obtained for arresters of different voltage levels, and the harmonic characteristics of the impact aging of the arrester varistor are further determined to obtain the online monitoring judgment criteria for the aging status of the arrester of the corresponding voltage level.

[0012] Furthermore, the varistor is at an initial power frequency voltage of 0.8u 1mAI When the optimal index ratio is between 0.025 and 0.03, the varistor has been degraded; when the ratio is between 0.04 and 0.05, the varistor is critically completely damaged.

[0013] Furthermore, the varistor is at the initial power frequency voltage u 1mAI When the optimal index ratio is between 0.225 and 0.275, the varistor has been degraded. When the ratio of the second harmonic to the fundamental amplitude rises to 0.35 to 0.4, it indicates that the varistor is critically completely damaged.

[0014] Furthermore, the optimal index is approximately linearly related to the number of impact groups.

[0015] Furthermore, Matlab simulation software is used to perform FFT analysis on the current waveform data of the resistive component of the leakage current.

[0016] Furthermore, the resistive component higher harmonics include odd harmonics and even harmonics.

[0017] Furthermore, based on FFT, harmonic characteristic analysis is performed on the leakage current and its resistive component current waveform data to obtain the amplitude variation trend of each higher harmonic current of the leakage current and its resistive component.

[0018] A storage medium stores a computer program, which implements the judgment method when executed by a processor.

[0019] A device comprises a memory, a processor and a determination method stored in the memory and executable on the processor.

[0020] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0021] (1) The present invention takes into account the odd-order and even-order harmonic characteristics of the leakage current of the varistor and its resistive component, and can obtain the optimal judgment index for characterizing the aging state of the varistor.

[0022] (2) The present invention proposes a method for aging the arrester varistor under the condition of an initial power frequency voltage of 0.8u 1mAI The ratio of the second harmonic to the fundamental amplitude of the resistive current under (operating voltage), A2 / A1, can be used as an online monitoring criterion for the aging status of in-service lightning arresters. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The ZnO varistor of the present invention is subjected to a 40kA and 2-time impact accelerated aging test. 1mAI The changing trend of the fundamental wave and harmonic amplitude of the leakage current;

[0024] Figure 2 The ZnO varistor of the present invention is subjected to a 40kA and 2-time impact accelerated aging test. 1mAI The change trend of the fundamental wave and each harmonic amplitude of the resistive component of the lower leakage current;

[0025] Figure 3 The ZnO varistor of the present invention is subjected to a 40kA and 2-time impact accelerated aging test. 1mAI The changing trend of the ratio of the amplitude of the odd harmonics to the fundamental wave of the leakage current;

[0026] Figure 4 The ZnO varistor of the present invention is subjected to a 40kA and 2-time impact accelerated aging test. 1mAI The changing trend of the ratio of the even harmonics to the fundamental amplitude of the lower leakage current;

[0027] Figure 5 The ZnO varistor of the present invention is subjected to a 40kA and 2-time impact accelerated aging test. 1mAI The changing trend of the ratio of the even harmonics to the fundamental amplitude of the resistive component of the lower leakage current;

[0028] Figure 6 The ZnO varistor of the present invention is subjected to a 40kA and 2-time impact accelerated aging test at 0.8u 1mAI Changing trend of the ratio of the second harmonic and fundamental amplitudes of the resistive component of the leakage current under (operating voltage). DETAILED DESCRIPTION

[0029] The present invention will be further described in detail below in conjunction with the examples, but the embodiments of the present invention are not limited thereto.

[0030] A method for determining the aging state of a lightning arrester comprises the following steps:

[0031] In this embodiment, the initial power frequency reference voltage u 1mAIThe change trend of the leakage current and its resistive component of each harmonic current amplitude is obtained, and the ratio of the even harmonic to the fundamental amplitude is obtained as the optimal indicator for judging the aging state of the arrester. Based on this, the initial power frequency reference voltage 0.8U 1mA The criterion for judging the aging state of lightning protection.

[0032] S1 conducts an accelerated aging test on the varistor sample with a current amplitude of 40kA and two times a group. After each group of tests, cool it to room temperature and measure the power frequency reference voltage u 1mAIA .

[0033] S2 After each test, cool the sample to room temperature and measure the initial power frequency reference voltage u 1mAI (0.8u 1mAI ) and use an oscilloscope to store the leakage current and its resistive component current waveform data.

[0034] S3 uses Matlab simulation software to study the impact aging process of the varistor under the initial power frequency voltage U 1mA The leakage current and its resistive component current waveform data are analyzed by FFT to obtain the amplitude of the fundamental wave and each higher harmonic, such as Figure 1 and Figure 2 shown.

[0035] S4 calculates the initial power frequency voltage u of the varistor during the impact aging process 1mAI The ratio of the leakage current and its resistive component higher harmonics to the fundamental amplitude, such as Figure 3 to Figure 5 As shown; and based on the test results, it is concluded that during the impact aging process of the varistor, the initial power frequency voltage u 1mAI The ratio of the even harmonics of the lower leakage current resistive component to the fundamental amplitude has an approximately linear relationship with the number of impact groups, which is the best indicator to characterize the impact aging state of the varistor. It is believed that when the ratio of the second harmonic to the fundamental amplitude rises to 0.27, the varistor has been degraded. When the ratio of the second harmonic to the fundamental amplitude rises to 0.39, it means that the varistor is critically completely damaged. Figure 5 shown.

[0036] S5 is based on S3 and S4. It uses Matlab simulation software to simulate the impact aging of the varistor at the initial power frequency voltage of 0.8u. 1mAI The FFT analysis of the current waveform data of the resistive component of the leakage current is performed to obtain the amplitude of the fundamental wave and each higher harmonic, and further calculate the initial power frequency voltage 0.8u during the impact aging process of the varistor. 1mAIThe ratio of the second harmonic to the fundamental amplitude of the resistive component of the leakage current is considered to be about 0.026, and the varistor has been degraded. When the ratio of the second harmonic to the fundamental amplitude rises to 0.037, it means that the varistor is critically damaged. Figure 6 It can also be used as a criterion for judging the aging status of in-service arresters in online monitoring.

[0037] S6 For arresters of different voltage levels, the above-mentioned S1-S5 impact aging test methods can be used to study the impact aging harmonic characteristics of arrester varistors, and propose criteria for judging the aging status in online monitoring of operating arresters.

[0038] The present invention uses the leakage current and its resistive component under the operating voltage of the zinc oxide arrester as the most common characteristic parameters for identifying the state of the zinc oxide varistor and facilitates online measurement, so as to effectively monitor the state of the zinc oxide arrester in real time.

[0039] Another embodiment of the present invention provides a computer-readable storage medium having a computer program stored thereon, and the computer program implements any of the above-mentioned determination methods when executed by a processor.

[0040] Another embodiment of the present invention provides a device, including a memory, a processor, and the determination method stored in the memory and executable on the processor.

[0041] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for determining the aging state of a lightning arrester, characterized in that: These include: The arrester varistor is subjected to impulse aging with impulse currents of different amplitudes and then cooled to room temperature; Under different amplitudes of impulse current impact aging, record the varistor at the initial power frequency reference voltage u 1mAI The leakage current and its resistive component are detected, and the leakage current and its resistive component current waveform data are saved; Perform harmonic characteristic analysis on the leakage current and its resistive component current waveform data based on FFT to obtain the fundamental amplitude of the leakage current and the resistive component of the leakage current and the amplitude of each higher harmonic of the leakage current and the resistive component of the leakage current; The ratio of the amplitude of each higher harmonic of the leakage current and the resistive component of the leakage current to the fundamental wave is obtained, and the optimal index for judging the aging state of the varistor is further obtained. The optimal index is the initial power frequency voltage. u 1mAI The ratio of the even harmonics of the resistive component of the leakage current to the fundamental amplitude of the resistive component of the leakage current; According to the above steps, the optimal index is obtained for arresters of different voltage levels, and the harmonic characteristics of the impact aging of the arrester varistor are further determined to obtain the online monitoring judgment criteria for the aging status of the arrester of the corresponding voltage level.

2. The determination method according to claim 1, characterized in that: The varistor chip has an initial power frequency voltage of 0.8 u 1mAI When the optimal index ratio is between 0.025 and 0.03, the varistor has been degraded; when the ratio is between 0.035 and 0.045, the varistor is critically completely damaged.

3. The determination method according to claim 1, characterized in that: The varistor is at the initial power frequency voltage u 1mAI When the optimal index ratio is between 0.225 and 0.275, the varistor has been degraded. When the ratio rises to 0.35 to 0.4, it indicates that the varistor is critically completely damaged.

4. The determination method according to claim 1, characterized in that: The optimal index is approximately linearly related to the number of impact groups.

5. The determination method according to any one of claims 1 to 4, characterized in that: Matlab simulation software is used to perform FFT analysis on the current waveform data of the resistive component of the leakage current.

6. The determination method according to claim 1, characterized in that: The resistive component high-order harmonics include odd harmonics and even harmonics.

7. The determination method according to claim 1, characterized in that: Based on FFT, harmonic characteristic analysis of leakage current and its resistive component current waveform data is performed to obtain the amplitude variation trend of each high-order harmonic current of leakage current and its resistive component.

8. A computer storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the judgment method according to any one of claims 1 to 7 is implemented.

9. A computer device, characterized in that: The method comprises a memory, a processor, and a determination method as claimed in any one of claims 1 to 7 which is stored in the memory and can be run on the processor.

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